[FORM OF SERIES B WARRANT] NANOGEN, INC.

Exhibit 10.4

[FORM OF SERIES B WARRANT]

NANOGEN, INC.

WARRANT TO PURCHASE COMMON STOCK

Warrant No.:                     

Date of Issuance: August     , 2007 (“Issuance Date”)

Nanogen, Inc., a Delaware corporation (the “Company”), hereby certifies that, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, [                                        ], the registered holder hereof or its permitted assigns (the “Holder”), is entitled, subject to the terms set forth below, to purchase from the Company, at the Exercise Price (as defined below) then in effect, upon surrender of this Warrant to Purchase Common Stock (including any Warrants to Purchase Common Stock issued in exchange, transfer or replacement hereof, the “Warrant”), at any time or times on or after the Initial Exercise Eligibility Date (as defined below), but not after 11:59 p.m., New York time, on the Expiration Date (as defined below), a number of fully paid nonassessable shares of Common Stock (as defined below) equal to the number of shares of Common Stock issued upon exercise of the Holder’s Series A Warrants from and after the Initial Exercise Eligibility Date (the “Warrant Shares”). This Warrant is one of the Warrants to purchase Common Stock (the “SPA Warrants”) issued pursuant to Section 1 of that certain Securities Purchase Agreement, dated as of August __, 2007 (the “Subscription Date”), by and among the Company and the investors (the “Buyers”) referred to therein (the “Securities Purchase Agreement”). Except as otherwise defined herein, capitalized terms in this Warrant shall have the meanings set forth in Section 15.

1. EXERCISE OF WARRANT.

(a) Mechanics of Exercise. Subject to the terms and conditions hereof (including, without limitation, the limitations set forth in Section 1(f)), this Warrant may be exercised by the Holder at any time or times on or after the Initial Exercise Eligibility Date, in whole or in part, by (i) delivery of a written notice, in the form attached hereto as Exhibit A (the “Exercise Notice”), of the Holder’s election to exercise this Warrant and (ii) (A) payment to the Company of an amount equal to the applicable Exercise Price multiplied by the number of Warrant Shares as to which this Warrant is being exercised (the “Aggregate Exercise Price”) in cash or by wire transfer of immediately available funds or (B) by notifying the Company that this Warrant is being exercised pursuant to a Cashless Exercise (as defined in Section 1(d)). The Holder shall not be required to deliver the original Warrant in order to effect an exercise hereunder. Execution and delivery of the Exercise Notice with respect to less than all of the Warrant Shares shall have the same effect as cancellation of the original Warrant and issuance of a new Warrant evidencing the right to purchase the remaining number of Warrant Shares. On or before the second (2^nd) Business Day following the date on which the Company has received each of the Exercise Notice and the Aggregate Exercise Price (or notice of a

Cashless Exercise) (the “Exercise Delivery Documents”), the Company shall transmit by facsimile an acknowledgment of confirmation of receipt of the Exercise Delivery Documents to the Holder and the Company’s transfer agent (the “Transfer Agent”). On or before the third (3^rd) Trading Day following the date on which the Company has received all of the Exercise Delivery Documents (the “Share Delivery Date”), the Company shall (X) provided that the Transfer Agent is participating in The Depository Trust Company (“DTC”) Fast Automated Securities Transfer Program, upon the request of the Holder, credit such aggregate number of Warrant Shares to which the Holder is entitled pursuant to such exercise to the Holder’s or its designee’s balance account with DTC through its Deposit Withdrawal Agent Commission system, or (Y) if the Transfer Agent is not participating in the DTC Fast Automated Securities Transfer Program, issue and dispatch by overnight courier to the address as specified in the Exercise Notice, a certificate, registered in the Company’s share register in the name of the Holder or its designee, for the number of shares of Common Stock to which the Holder is entitled pursuant to such exercise. Upon delivery of the Exercise Delivery Documents, the Holder shall be deemed for all corporate purposes to have become the holder of record of the Warrant Shares with respect to which this Warrant has been exercised, irrespective of the date such Warrant Shares are credited to the Holder’s DTC account or the date of delivery of the certificates evidencing such Warrant Shares, as the case may be. If this Warrant is submitted in connection with any exercise pursuant to this Section 1(a) and the number of Warrant Shares represented by this Warrant submitted for exercise is greater than the number of Warrant Shares being acquired upon an exercise, then the Company shall as soon as practicable and in no event later than three (3) Business Days after any exercise and at its own expense, issue a new Warrant (in accordance with Section 7(d)) representing the right to purchase the number of Warrant Shares purchasable immediately prior to such exercise under this Warrant, less the number of Warrant Shares with respect to which this Warrant is exercised. No fractional shares of Common Stock are to be issued upon the exercise of this Warrant, but rather the number of shares of Common Stock to be issued shall be rounded up to the nearest whole number. The Company shall pay any and all transfer and similar taxes (other than income and similar taxes) which may be payable with respect to the issuance and delivery of Warrant Shares upon exercise of this Warrant. NOTWITHSTANDING ANY PROVISION OF THIS WARRANT TO THE CONTRARY, NO MORE THAN THE MAXIMUM ELIGIBILITY NUMBER OF WARRANT SHARES SHALL BE EXERCISABLE HEREUNDER.

(b) Exercise Price. For purposes of this Warrant, “Exercise Price” means (1) with respect to the number of Warrant Shares that become exercisable in any calendar quarter, as set forth in column (2) of Schedule I hereto, the Exercise Price listed in column (4) to Schedule I opposite such number of Warrant Shares and (2) with respect to any portion of this Warrant not previously exercisable on the date when all Series A Warrants have been exercised, 110% of the Closing Sale Price on such date, in each case subject to adjustment as provided herein, provided that unless and until such time as the Company receives the Required Stockholder Approval (as defined below), the Exercise Price shall not be less than the Exercise Floor Price.

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(c) Company’s Failure to Timely Deliver Securities. If the Company shall fail for any reason or for no reason to issue to the Holder within five (5) Business Days of receipt of the Exercise Delivery Documents, a certificate for the number of shares of Common Stock to which the Holder is entitled and register such shares of Common Stock on the Company’s share register or to credit the Holder’s balance account with DTC for such number of shares of Common Stock to which the Holder is entitled upon the Holder’s exercise of this Warrant, then, in addition to all other remedies available to the Holder, the Company shall pay in cash to the Holder on each day after such fifth (5^th) Business Day that the issuance of such shares of Common Stock is not timely effected an amount equal to 1.0% of the product of (A) the sum of the number of shares of Common Stock not issued to the Holder on a timely basis and to which the Holder is entitled and (B) the Weighted Average Price of the shares of Common Stock on the Trading Day immediately preceding the last possible date which the Company could have issued such shares of Common Stock to the Holder without violating Section 1(a). In addition to the foregoing, if within three (3) Trading Days after the Company’s receipt of the facsimile copy of the Exercise Delivery Documents the Company shall fail to issue and deliver a certificate to the Holder and register such shares of Common Stock on the Company’s share register or credit the Holder’s balance account with DTC for the number of shares of Common Stock to which the Holder is entitled upon the Holder’s exercise hereunder, and if on or after such Trading Day the Holder purchases (in an open market transaction or otherwise) shares of Common Stock to deliver in satisfaction of a sale by the Holder of shares of Common Stock issuable upon such exercise that the Holder anticipated receiving from the Company (a “Buy-In”), then the Company shall, within five (5) Business Days after the Holder’s request and in the Holder’s discretion, either (i) pay cash to the Holder in an amount equal to the Holder’s total purchase price (including brokerage commissions, if any) for the shares of Common Stock so purchased (the “Buy-In Price”), at which point the Company’s obligation to deliver such certificate (and to issue such Warrant Shares) shall terminate, or (ii) promptly honor its obligation to deliver to the Holder a certificate or certificates representing such Warrant Shares and pay cash to the Holder in an amount equal to the excess (if any) of the Buy-In Price over the product of (A) such number of shares of Common Stock, times (B) the Weighted Average Price on the date of exercise.

(d) Cashless Exercise. Notwithstanding anything contained herein to the contrary, if a registration statement covering the issuance of the Warrant Shares that are the subject of the Exercise Notice by the Holder pursuant to the 1933 Act (the “Unavailable Warrant Shares”) is not available for the issuance of such Unavailable Warrant Shares, the Holder may, in its sole discretion, exercise this Warrant in whole or in part and, in lieu of making the cash payment otherwise contemplated to be made to the Company upon such exercise in payment of the Aggregate Exercise Price, elect instead to receive upon such exercise the “Net Number” of shares of Common Stock determined according to the following formula (a “Cashless Exercise”):

For purposes of the foregoing formula:

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(e) Disputes. In the case of a dispute as to the determination of the Exercise Price or the arithmetic calculation of the Warrant Shares, the Company shall promptly issue to the Holder the number of Warrant Shares that are not disputed and resolve such dispute in accordance with Section 12.

(f) Limitations on Exercises; Beneficial Ownership.

(i) The Company shall not effect the exercise of this Warrant, and the Holder shall not have the right to exercise this Warrant, to the extent that after giving effect to such exercise, such Person (together with such Person’s affiliates) would beneficially own in excess of 4.99% the “Maximum Percentage”) of the shares of Common Stock outstanding immediately after giving effect to such exercise. For purposes of the foregoing sentence, the aggregate number of shares of Common Stock beneficially owned by such Person and its affiliates shall include the number of shares of Common Stock issuable upon exercise of this Warrant with respect to which the determination of such sentence is being made, but shall exclude shares of Common Stock which would be issuable upon (x) exercise of the remaining, unexercised portion of this Warrant beneficially owned by such Person and its affiliates and (y) exercise or conversion of the unexercised or unconverted portion of any other securities of the Company beneficially owned by such Person and its affiliates (including, without limitation, any convertible notes or convertible preferred stock or warrants) subject to a limitation on conversion or exercise analogous to the limitation contained herein. Except as set forth in the preceding sentence, for purposes of this paragraph, beneficial ownership shall be calculated in accordance with Section 13(d) of the Securities Exchange Act of 1934, as amended. For purposes of this Warrant, in determining the number of outstanding shares of Common Stock, the Holder may rely on the number of outstanding shares of Common Stock as reflected in (1) the Company’s most recent Form 10-K, Form 10-KSB, Form 10-Q, Form 10-QSB, Current Report on Form 8-K or other public filing with the Securities and Exchange Commission (“SEC”) as the case may be, (2) a more recent public announcement by the Company or (3) any other notice by the Company or the Transfer Agent setting forth the number of shares of Common Stock outstanding. For any reason at any time, upon the written request of the

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Holder, the Company shall within two (2) Business Days confirm orally and in writing to the Holder the number of shares of Common Stock then outstanding. In any case, the number of outstanding shares of Common Stock shall be determined after giving effect to the conversion or exercise of securities of the Company by the Holder and its affiliates since the date as of which such number of outstanding shares of Common Stock was reported. By written notice to the Company, the Holder may from time to time increase or decrease the Maximum Percentage to any other percentage not in excess of 9.99% specified in such notice; provided that any such increase will not be effective until the sixty-first (61^st) day after such notice is delivered to the Company.

(ii) Principal Market Regulation. The Company shall not be obligated to issue any shares of Common Stock upon exercise of this Warrant and the Holder shall not have the right to receive upon exercise of this Warrant any shares of Common Stock, if the issuance of such shares of Common Stock would exceed the aggregate number of shares of Common Stock which the Company may issue upon exercise of this Warrant (including, as applicable, any shares of Common Stock issued upon conversion of the SPA Securities) without breaching the Company’s obligations under the rules or regulations of the Principal Market (the “Exchange Cap”), except that such limitation shall not apply in the event that the Company (A) obtains the approval of its stockholders as required by the applicable rules of the Principal Market for issuances of shares of Common Stock in excess of such amount or (B) obtains a written opinion from outside counsel to the Company that such approval is not required, which opinion shall be reasonably satisfactory to the Required Holders. Until such approval or written opinion is obtained, no Holder shall be issued, upon exercise or conversion, as applicable, of any SPA Warrants or SPA Securities, shares of Common Stock in an amount greater than the product of the Exchange Cap multiplied by a fraction, the numerator of which is the total number of shares of Common Stock issued to such Holder pursuant to the Securities Purchase Agreement on the Issuance Date and the denominator of which is the aggregate number of shares of Common Stock issued to the Holders pursuant to the Securities Purchase Agreement on the Issuance Date (with respect to each Holder, the “Exchange Cap Allocation”). In the event that any Holder shall sell or otherwise transfer any of such Holder’s SPA Warrants, the transferee shall be allocated a pro rata portion of such Holder’s Exchange Cap Allocation, and the restrictions of the prior sentence shall apply to such transferee with respect to the portion of the Exchange Cap Allocation allocated to such transferee. In the event that any Holder of SPA Warrants shall exercise all of such Holder’s SPA Warrants into a number of shares of Common Stock which, in the aggregate, is less than such Holder’s Exchange Cap Allocation, then the difference between such Holder’s Exchange Cap Allocation and the number of shares of Common Stock actually issued to such Holder shall

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be allocated to the respective Exchange Cap Allocations of the remaining Holders of SPA Warrants on a pro rata basis in proportion to the shares of Common Stock underlying the SPA Warrants then held by each such Holder. In the event that the Company is prohibited from issuing any Warrant Shares for which an Exercise Notice has been received as a result of the operation of this Section 1(f)(ii), the Company shall pay cash in exchange for cancellation of such Warrant Shares, at a price per Warrant Share equal to the difference between the Closing Sale Price and the Exercise Price as of the date of the attempted exercise.

(g) Insufficient Authorized Shares. If at any time while this Warrant remain outstanding the Company does not have a sufficient number of authorized and unreserved shares of Common Stock to satisfy its obligation to reserve for issuance upon exercise of this Warrant at least a number of shares of Common Stock equal to 120% (the “Required Reserve Amount”) of the number of shares of Common Stock as shall from time to time be necessary to effect the exercise of all of this Warrant then outstanding (an “Authorized Share Failure”), then the Company shall immediately take all action necessary to increase the Company’s authorized shares of Common Stock to an amount sufficient to allow the Company to reserve the Required Reserve Amount for this Warrant then outstanding. Without limiting the generality of the foregoing sentence, as soon as practicable after the date of the occurrence of an Authorized Share Failure, but in no event later than ninety (90) days after the occurrence of such Authorized Share Failure, the Company shall hold a meeting of its stockholders for the approval of an increase in the number of authorized shares of Common Stock. In connection with such meeting, the Company shall provide each stockholder with a proxy statement and shall use its best efforts to solicit its stockholders’ approval of such increase in authorized shares of Common Stock and to cause its board of directors to recommend to the stockholders that they approve such proposal.

(h) Scheduling of Warrant Shares. Within 30 days after the end of each calendar quarter after the Issuance Date while this Warrant is outstanding, as set forth in column (1) on Schedule I attached hereto, the Holder shall record on Schedule I attached hereto and provide a copy to the Company (i) in column (2), the number of the Holder’s Series A Warrants exercised (or deemed exercised as determined below) during such calendar quarter; provided, that if less than 100,000 of the Holder’s Series A Warrants are exercised in such calendar quarter, for purposes hereof such Series A Warrants so exercised will be carried forward successively until the earliest calendar quarter in which at least 100,000 of the Holder’s Series A Warrants have been exercised (or so deemed exercised) in the aggregate since the last calendar quarter in which any portion of this Warrant has become exercisable and such Series A Warrants will be deemed to have been exercised in the applicable subsequent calendar quarter, (ii) in column (3), the Maximum Eligibility Number for each calendar quarter, which shall equal the Maximum Eligibility Number from the prior calendar quarter plus the number of Warrant Shares indicated in column (2) for such calendar quarter, and (iii) in column (4), the Exercise Price for the Warrant Shares specified in column (2) of such schedule, which shall equal 110% of the Closing Sale Price on the last Trading Day of such calendar quarter. Notwithstanding the

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foregoing, on the date when all of the Series A Warrants are exercised, the entire amount of this Warrant shall immediately become exercisable, the Maximum Eligibility Amount shall be [                    ], as adjusted for any stock dividend, stock split, stock combination, reclassification or similar transaction and the Exercise Price for any previously unexercisable portion of this Warrant shall be equal to 110% of the Closing Sale Price, on such date.

2. ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF WARRANT SHARES. The Exercise Price and the number of Warrant Shares shall be adjusted from time to time as follows:

(a) Adjustment upon Issuance of shares of Common Stock. If and whenever on or after the Subscription Date and through the eighteen (18) month anniversary of the Issuance Date, the Company issues or sells, or in accordance with this Section 2 is deemed to have issued or sold, any shares of Common Stock (including the issuance or sale of shares of Common Stock owned or held by or for the account of the Company, but excluding shares of Common Stock deemed to have been issued by the Company in connection with any Excluded Securities (as defined in the SPA Securities) for a consideration per share (the “New Issuance Price”) less than a price (the “Applicable Price”) equal to the Exercise Price in effect immediately prior to such issue or sale or deemed issuance or sale (the foregoing a “Dilutive Issuance”), then immediately after such Dilutive Issuance, the Exercise Price then in effect shall be reduced to an amount equal to the New Issuance Price. In the event of any Dilutive Issuance after the eighteen (18) month anniversary of the Issuance Date, then immediately after such Dilutive Issuance, the Exercise Price then in effect shall be reduced to an amount equal to the product of (A) the Exercise Price in effect immediately prior to such Dilutive Issuance and (B) the quotient determined by dividing (1) the sum of (I) the product derived by multiplying the Exercise Price in effect immediately prior to such Dilutive Issuance and the number of shares of Common Stock Deemed Outstanding immediately prior to such Dilutive Issuance plus (II) the consideration, if any, received by the Company upon such Dilutive Issuance, by (2) the product derived by multiplying (I) the Exercise Price in effect immediately prior to such Dilutive Issuance by (II) the number of shares of Common Stock Deemed Outstanding immediately after such Dilutive Issuance. Upon each such adjustment of the Exercise Price hereunder, the number of Warrant Shares shall be adjusted to the number of shares of Common Stock determined by multiplying the Exercise Price in effect immediately prior to such adjustment by the number of Warrant Shares acquirable upon exercise of this Warrant immediately prior to such adjustment and dividing the product thereof by the Exercise Price resulting from such adjustment. For purposes of determining the adjusted Exercise Price under this Section 2(a), the following shall be applicable:

(i) Issuance of Options. If the Company in any manner grants any Options and the lowest price per share for which one share of Common Stock is issuable upon the exercise of any such Option or upon conversion, exercise or exchange of any Convertible Securities issuable upon exercise of any such Option is less than the Applicable Price, then such share of Common Stock shall be deemed to be outstanding and to have been issued and sold by the Company at the time of the granting or

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sale of such Option for such price per share. For purposes of this Section 2(a)(i), the “lowest price per share for which one share of Common Stock is issuable upon exercise of such Options or upon conversion, exercise or exchange of such Convertible Securities issuable upon exercise of any such Option” shall be equal to the sum of the lowest amounts of consideration (if any) received or receivable by the Company with respect to any one share of Common Stock upon the granting or sale of the Option, upon exercise of the Option and upon conversion, exercise or exchange of any Convertible Security issuable upon exercise of such Option. No further adjustment of the Exercise Price or number of Warrant Shares shall be made upon the actual issuance of such shares of Common Stock or of such Convertible Securities upon the exercise of such Options or upon the actual issuance of such shares of Common Stock upon conversion, exercise or exchange of such Convertible Securities.

(ii) Issuance of Convertible Securities. If the Company in any manner issues or sells any Convertible Securities and the lowest price per share for which one share of Common Stock is issuable upon the conversion, exercise or exchange thereof is less than the Applicable Price, then such share of Common Stock shall be deemed to be outstanding and to have been issued and sold by the Company at the time of the issuance or sale of such Convertible Securities for such price per share. For the purposes of this Section 2(a)(ii), the “lowest price per share for which one share of Common Stock is issuable upon the conversion, exercise or exchange thereof” shall be equal to the sum of the lowest amounts of consideration (if any) received or receivable by the Company with respect to one share of Common Stock upon the issuance or sale of the Convertible Security and upon conversion, exercise or exchange of such Convertible Security. No further adjustment of the Exercise Price or number of Warrant Shares shall be made upon the actual issuance of such shares of Common Stock upon conversion, exercise or exchange of such Convertible Securities, and if any such issue or sale of such Convertible Securities is made upon exercise of any Options for which adjustment of this Warrant has been or is to be made pursuant to other provisions of this Section 2(a), no further adjustment of the Exercise Price or number of Warrant Shares shall be made by reason of such issue or sale.

(iii) Change in Option Price or Rate of Conversion. If the purchase price provided for in any Options, the additional consideration, if any, payable upon the issue, conversion, exercise or exchange of any Convertible Securities, or the rate at which any Convertible Securities are convertible into or exercisable or exchangeable for shares of Common Stock increases or decreases at any time, then the Exercise Price and the number of Warrant Shares in effect at the time of such increase or decrease shall be adjusted to the Exercise Price and the number of Warrant Shares which would have been in effect at such time had such Options or

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Convertible Securities provided for such increased or decreased purchase price, additional consideration or increased or decreased conversion rate, as the case may be, at the time initially granted, issued or sold. For purposes of this Section 2(a)(iii), if the terms of any Option or Convertible Security that was outstanding as of the date of issuance of this Warrant are increased or decreased in the manner described in the immediately preceding sentence, then such Option or Convertible Security and the shares of Common Stock deemed issuable upon exercise, conversion or exchange thereof shall be deemed to have been issued as of the date of such increase or decrease. No adjustment pursuant to this Section 2(a) shall be made if such adjustment would result in an increase of the Exercise Price then in effect or a decrease in the number of Warrant Shares.

(iv) Calculation of Consideration Received. In case any Option is issued in connection with the issue or sale of other securities of the Company, together comprising one integrated transaction in which no specific consideration is allocated to such Options by the parties thereto, the Options will be deemed to have been issued for a consideration of $0.01. If any shares of Common Stock, Options or Convertible Securities are issued or sold or deemed to have been issued or sold for cash, the consideration received therefor will be deemed to be the net amount received by the Company therefor. If any shares of Common Stock, Options or Convertible Securities are issued or sold for a consideration other than cash, the amount of such consideration received by the Company will be the fair value of such consideration, except where such consideration consists of securities, in which case the amount of consideration received by the Company will be the Weighted Average Price of such security on the date of receipt. If any shares of Common Stock, Options or Convertible Securities are issued to the owners of the non-surviving entity in connection with any merger in which the Company is the surviving entity, the amount of consideration therefor will be deemed to be the fair value of such portion of the net assets and business of the non-surviving entity as is attributable to such shares of Common Stock, Options or Convertible Securities, as the case may be. The fair value of any consideration other than cash or securities will be determined jointly by the Company and the Required Holders. If such parties are unable to reach agreement within ten (10) days after the occurrence of an event requiring valuation (the “Valuation Event”), the fair value of such consideration will be determined within five (5) Business Days after the tenth (10^th) day following the Valuation Event by an independent, reputable appraiser jointly selected by the Company and the Required Holders. The determination of such appraiser shall be final and binding upon all parties absent manifest error and the fees and expenses of such appraiser shall be borne by the Company.

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(v) Record Date. If the Company takes a record of the holders of shares of Common Stock for the purpose of entitling them (A) to receive a dividend or other distribution payable in shares of Common Stock, Options or in Convertible Securities or (B) to subscribe for or purchase shares of Common Stock, Options or Convertible Securities, then such record date will be deemed to be the date of the issue or sale of the shares of Common Stock deemed to have been issued or sold upon the declaration of such dividend or the making of such other distribution or the date of the granting of such right of subscription or purchase, as the case may be.

(vi) Unless and until such time as the Company receives any stockholder approval that may be required under any applicable stockholder approval provisions in order to allow the Exercise Price to be less than the Exercise Floor Price (as defined below), including, without limitation, under the rules and regulations of any exchange or automated quotation system on which any of the securities of the Company are listed or designated (the “Required Stockholder Approval”), no adjustment pursuant to Sections 2(a) and 3(a) shall cause the Exercise Price to be less than $[                    ], as adjusted for any stock dividend, stock split, stock combination, reclassification or similar transaction (the “Exercise Floor Price”).

(b) Adjustment upon Subdivision or Combination of Common Stock. If the Company at any time on or after the Subscription Date subdivides (by any stock split, stock dividend, recapitalization or otherwise) one or more classes of its outstanding shares of Common Stock into a greater number of shares, the Exercise Price in effect immediately prior to such subdivision will be proportionately reduced and the number of Warrant Shares will be proportionately increased. If the Company at any time on or after the Subscription Date combines (by combination, reverse stock split or otherwise) one or more classes of its outstanding shares of Common Stock into a smaller number of shares, the Exercise Price in effect immediately prior to such combination will be proportionately increased and the number of Warrant Shares will be proportionately decreased. Any adjustment under this Section 2(b) shall become effective at the close of business on the date the subdivision or combination becomes effective.

(c) Other Events. If any event occurs of the type contemplated by the provisions of this Section 2 but not expressly provided for by such provisions (including, without limitation, the granting of stock appreciation rights, phantom stock rights or other rights with equity features), then the Company’s Board of Directors will make an appropriate adjustment in the Exercise Price and the number of Warrant Shares so as to protect the rights of the Holder; provided that no such adjustment pursuant to this Section 2(c) will increase the Exercise Price then in effect or decrease the number of Warrant Shares as otherwise determined pursuant to this Section 2.

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(d) De Minimis Adjustments. No adjustment in the Exercise Price shall be required unless such adjustment would require an increase or decrease of at least $0.01 in such price; provided, however, that any adjustment which by reason of this Section 2(d) is not required to be made shall be carried forward and taken into account in any subsequent adjustments under this Section 2. All calculations under this Section 2 shall be made by the Company in good faith and shall be made to the nearest cent or to the nearest one hundredth of a share, as applicable. No adjustment need be made for a change in the par value or no par value of the Company’s Common Stock.

3. RIGHTS UPON DISTRIBUTION OF ASSETS. If the Company shall declare or make any dividend (other than a dividend issued under Section 2(b) herein) or other distribution of its assets (or rights to acquire its assets) to holders of shares of Common Stock, by way of return of capital or otherwise (including, without limitation, any distribution of cash, stock or other securities, property or options by way of a dividend, spin off, reclassification, corporate rearrangement, scheme of arrangement or other similar transaction) (a “Distribution”), at any time after the issuance of this Warrant, then, in each such case any Exercise Price in effect immediately prior to the close of business on the record date fixed for the determination of holders of shares of Common Stock entitled to receive the Distribution shall be reduced, effective as of the close of business on such record date, to a price determined by multiplying such Exercise Price by a fraction of which (i) the numerator shall be the Weighted Average Price of the shares of Common Stock on the Trading Day immediately preceding such record date minus the value of the Distribution (as determined in good faith by the Company’s Board of Directors) applicable to one share of Common Stock, and (ii) the denominator shall be the Weighted Average Price of the shares of Common Stock on the Trading Day immediately preceding such record date.

4. PURCHASE RIGHTS; FUNDAMENTAL TRANSACTIONS.

(a) Purchase Rights. In addition to any adjustments pursuant to Section 2 above, if at any time the Company grants, issues or sells any Options, Convertible Securities or rights to purchase stock, warrants, securities or other property pro rata to the record holders of any class of shares of Common Stock (the “Purchase Rights”), then the Holder will be entitled to acquire, upon the terms applicable to such Purchase Rights, the aggregate Purchase Rights which the Holder could have acquired if the Holder had held the number of shares of Common Stock acquirable upon complete exercise of this Warrant (without regard to any limitations on the exercise of this Warrant) immediately before the date on which a record is taken for the grant, issuance or sale of such Purchase Rights, or, if no such record is taken, the date as of which the record holders of shares of Common Stock are to be determined for the grant, issue or sale of such Purchase Rights.

(b) Fundamental Transactions. No sooner than fifteen (15) days and nor later than ten (10) days prior to the consummation of a Fundamental Transaction, but not prior to the public announcement of such Fundamental Transaction, the Company shall deliver written notice thereof via facsimile and overnight courier to the Holder (a “Fundamental Transaction Notice”).

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(1) Reaffirmation. If the Company enters into or is a party to a Fundamental Transaction in which it is the Successor Entity, the Company shall deliver to the Holder (i) an affirmation that this Warrant shall be a continuing obligation of the Company, or the Company as the Successor Entity, and a reaffirmation of the Company’s, or the Company’s as the Successor Entity, obligations under the Transaction Documents following such Fundamental Transaction and (ii) a confirmation that there shall be issued upon exercise of this Warrant at any time after the consummation of the Fundamental Transaction (the “Fundamental Transaction Closing Date”), (A) Common Stock or such other shares of publicly traded common stock (or their equivalent) of the Company, or the Company as the Successor Entity, or (B) if the Company is not a publicly traded entity following such Fundamental Transaction, in lieu of the shares of the Company’s Common Stock (or other securities, cash, assets or other property) issuable upon exercise of the Warrants prior to such Fundamental Transaction, such shares of stock, securities, cash, assets or any other property whatsoever (including warrants or other purchase or subscription rights) which the Holder would have been entitled to receive upon the happening of such Fundamental Transaction had this Warrant been exercised immediately prior to such Fundamental Transaction, in each case as adjusted in accordance with the provisions of this Warrant. In addition to and not in substitution for any other rights hereunder, prior to the consummation of any Fundamental Transaction in which the Company is the Successor Entity, pursuant to which holders of shares of Common Stock are entitled to receive securities or other assets with respect to or in exchange for shares of Common Stock (a “Corporate Event”), the Company shall make appropriate provision to insure that the Holder will thereafter have the right to receive upon an exercise of this Warrant at any time after the Fundamental Transaction Closing Date but prior to the Expiration Date, in lieu of the shares of the Common Stock (or other securities, cash, assets or other property) issuable upon the exercise of this Warrant prior to such Fundamental Transaction, such shares of stock, securities, cash, assets or any other property whatsoever (including warrants or other purchase or subscription rights) which the Holder would have been entitled to receive upon the happening of such Fundamental Transaction had this Warrant been exercised immediately prior to such Fundamental Transaction. Provision made pursuant to the preceding sentence shall be in a form and substance reasonably satisfactory to the Holder. The provisions of this Section shall apply similarly and equally to successive Fundamental Transactions and Corporate Events and shall be applied without regard to any limitations on the exercise of this Warrant. Notwithstanding the foregoing, the Holder acknowledges that in connection with any Fundamental Transaction in which the Company is not the Successor Entity, the Holder shall only have the rights set forth in Sections 4(b)(2) and 4(b)(3) hereof.

(2) Fundamental Transaction Exchange. At any time during the period beginning on the date of the Holder’s receipt of a Fundamental Transaction Notice and ending on the thirtieth (30^th) day (the “Automatic Exchange Date”) after the Fundamental Transaction Closing Date, the Holder

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may require the Company to exchange this Warrant (a “Fundamental Transaction Exchange”), within ten (10) Business Days after such request (or, if later, on the Fundamental Transaction Closing Date), in lieu of the shares of the Common Stock (or other securities, cash, assets or other property) issuable upon the exercise of this Warrant prior to such Fundamental Transaction, for such shares of stock, securities, cash, assets or any other property whatsoever (including warrants or other purchase or subscription rights) which the Holder would have been entitled to receive upon the happening of such Fundamental Transaction had this Warrant been exercised immediately prior to such Fundamental Transaction. If the Fundamental Transaction Exchange has not occurred prior to the Automatic Exchange Date and the Holder has not delivered a Black Scholes Notice (as defined below) prior to the Automatic Exchange Date, the Fundamental Transaction Exchange automatically shall occur on the Automatic Exchange Date.

(3) Black Scholes Value. Notwithstanding the foregoing, in the event of a Fundamental Transaction, at the request of the Holder delivered before the Automatic Exchange Date (a “Black Scholes Notice”), the Company (or the Successor Entity) shall purchase this Warrant from the Holder by paying to the Holder, within ten (10) Business Days after such request (or, if later, on the effective date of the Fundamental Transaction), cash in an amount equal to the Black Scholes Value of the remaining unexercised portion of this Warrant on the date of such Fundamental Transaction.

5. NONCIRCUMVENTION. The Company hereby covenants and agrees that the Company will not, by amendment of its Certificate of Incorporation, Bylaws or through any reorganization, transfer of assets, consolidation, merger, scheme of arrangement, dissolution, issue or sale of securities, or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Warrant, and will at all times in good faith carry out all the provisions of this Warrant and take all action as may be required to protect the rights of the Holder. Without limiting the generality of the foregoing, the Company (i) shall not increase the par value of any shares of Common Stock receivable upon the exercise of this Warrant above the Exercise Price then in effect, (ii) shall take all such actions as may be necessary or appropriate in order that the Company may validly and legally issue fully paid and nonassessable shares of Common Stock upon the exercise of this Warrant and (iii) shall, so long as any of the SPA Warrants are outstanding, take all action necessary to reserve and keep available out of its authorized and unissued shares of Common Stock, solely for the purpose of effecting the exercise of the SPA Warrants, 120% of the number of shares of Common Stock as shall from time to time be necessary to effect the exercise of the SPA Warrants then outstanding (without regard to any limitations on exercise.

6. WARRANT HOLDER NOT DEEMED A STOCKHOLDER. Except as otherwise specifically provided herein, the Holder, solely in such Person’s capacity as a holder of this Warrant, shall not be entitled to vote or receive dividends or be deemed the holder of share capital of the Company for any purpose, nor shall anything contained in this Warrant be construed to confer upon the Holder, solely in such Person’s capacity as the Holder of this

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Warrant, any of the rights of a shareholder of the Company or any right to vote, give or withhold consent to any corporate action (whether any reorganization, issue of stock, reclassification of stock, consolidation, merger, conveyance or otherwise), receive notice of meetings, receive dividends or subscription rights, or otherwise, prior to the issuance to the Holder of the Warrant Shares which such Person is then entitled to receive upon the due exercise of this Warrant. Except as set forth in Section 1(h), nothing contained in this Warrant shall be construed as imposing any liabilities on the Holder to purchase any securities (upon exercise of this Warrant or otherwise) or as a shareholder of the Company, whether such liabilities are asserted by the Company or by creditors of the Company. Notwithstanding this Section 6, the Company shall provide the Holder with copies of the same notices and other information given to the shareholders of the Company generally, contemporaneously with the giving thereof to the shareholders.

7. REISSUANCE OF WARRANTS.

(a) Transfer of Warrant. If this Warrant is to be transferred, the Holder shall surrender this Warrant to the Company, whereupon the Company will forthwith issue and deliver upon the order of the Holder a new Warrant (in accordance with Section 7(d)), registered as the Holder may request, representing the right to purchase the number of Warrant Shares being transferred by the Holder and, if less than the total number of Warrant Shares then underlying this Warrant is being transferred, a new Warrant (in accordance with Section 7(d)) to the Holder representing the right to purchase the number of Warrant Shares not being transferred; provided, that prior to any transfer of this Warrant, each transferee of this Warrant shall acknowledge and agree to its obligations under Section 1(h) hereof.

(b) Lost, Stolen or Mutilated Warrant. Upon receipt by the Company of evidence reasonably satisfactory to the Company of the loss, theft, destruction or mutilation of this Warrant, and, in the case of loss, theft or destruction, of any indemnification undertaking by the Holder to the Company in customary form and, in the case of mutilation, upon surrender and cancellation of this Warrant, the Company shall execute and deliver to the Holder a new Warrant (in accordance with Section 7(d)) representing the right to purchase the Warrant Shares then underlying this Warrant.

(c) Exchangeable for Multiple Warrants. This Warrant is exchangeable, upon the surrender hereof by the Holder at the principal office of the Company, for a new Warrant or Warrants (in accordance with Section 7(d)) representing in the aggregate the right to purchase the number of Warrant Shares then underlying this Warrant, and each such new Warrant will represent the right to purchase such portion of such Warrant Shares as is designated by the Holder at the time of such surrender; provided, however, that no Warrants for fractional shares of Common Stock shall be given.

(d) Issuance of New Warrants. Whenever the Company is required to issue a new Warrant pursuant to the terms of this Warrant, such new Warrant (i) shall be of like tenor with this Warrant, (ii) shall represent, as indicated on the face of such new Warrant, the right to purchase the Warrant Shares then underlying this Warrant (or in

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the case of a new Warrant being issued pursuant to Section 7(a) or Section 7(c), the Warrant Shares designated by the Holder which, when added to the number of shares of Common Stock underlying the other new Warrants issued in connection with such issuance, does not exceed the number of Warrant Shares then underlying this Warrant), (iii) shall have an issuance date, as indicated on the face of such new Warrant which is the same as the Issuance Date, and (iv) shall have the same rights and conditions as this Warrant.

8. NOTICES. Whenever notice is required to be given under this Warrant, unless otherwise provided herein, such notice shall be given in accordance with Section 9(f) of the Securities Purchase Agreement. The Company shall provide the Holder with prompt written notice of all actions taken pursuant to this Warrant, including in reasonable detail a description of such action and the reason therefore. Without limiting the generality of the foregoing, the Company will give written notice to the Holder (i) immediately upon any adjustment of the Exercise Price, setting forth in reasonable detail, within one (1) Business Day certifying, the calculation of such adjustment and (ii) at least fifteen (15) days prior to the date on which the Company closes its books or takes a record (A) with respect to any dividend or distribution upon the shares of Common Stock, (B) with respect to any grants, issuances or sales of any Options, Convertible Securities or rights to purchase stock, warrants, securities or other property to holders of shares of Common Stock (other than Excluded Securities) or (C) for determining rights to vote with respect to any Fundamental Transaction, dissolution or liquidation, provided in each case that such information shall be made known to the public prior to or in conjunction with such notice being provided to the Holder.

9. AMENDMENT AND WAIVER. Except as otherwise provided herein, the provisions of this Warrant may be amended and the Company may take any action herein prohibited, or omit to perform any act herein required to be performed by it, only if the Company has obtained the written consent of the Required Holders; provided that no such action may increase the exercise price of any SPA Warrant or decrease the number of shares or class of stock obtainable upon exercise of any SPA Warrant without the written consent of the Holder. No such amendment shall be effective to the extent that it applies to less than all of the holders of the SPA Warrants then outstanding.

10. GOVERNING LAW. This Warrant shall be governed by and construed and enforced in accordance with, and all questions concerning the construction, validity, interpretation and performance of this Warrant shall be governed by, the internal laws of the State of New York, without giving effect to any choice of law or conflict of law provision or rule (whether of the State of New York or any other jurisdictions) that would cause the application of the laws of any jurisdictions other than the State of New York.

11. CONSTRUCTION; HEADINGS. This Warrant shall be deemed to be jointly drafted by the Company and all the Buyers and shall not be construed against any person as the drafter hereof. The headings of this Warrant are for convenience of reference and shall not form part of, or affect the interpretation of, this Warrant.

12. DISPUTE RESOLUTION. In the case of a dispute as to the determination of the Exercise Price or the arithmetic calculation of the Warrant Shares, the Company shall

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submit the disputed determinations or arithmetic calculations via facsimile within two (2) Business Days of receipt of the Exercise Notice giving rise to such dispute, as the case may be, to the Holder. If the Holder and the Company are unable to agree upon such determination or calculation of the Exercise Price or the Warrant Shares within three Business Days of such disputed determination or arithmetic calculation being submitted to the Holder, then the Company shall, within two (2) Business Days submit via facsimile (a) the disputed determination of the Exercise Price to an independent, reputable investment bank selected by the Company and approved by the Holder or (b) the disputed arithmetic calculation of the Warrant Shares to the Company’s independent, outside accountant. The Company shall cause at its expense the investment bank or the accountant, as the case may be, to perform the determinations or calculations and notify the Company and the Holder of the results no later than ten Business Days from the time it receives the disputed determinations or calculations. Such investment bank’s or accountant’s determination or calculation, as the case may be, shall be binding upon all parties absent demonstrable error.

13. REMEDIES, OTHER OBLIGATIONS, BREACHES AND INJUNCTIVE RELIEF. The remedies provided in this Warrant shall be cumulative and in addition to all other remedies available under this Warrant and the other Transaction Documents, at law or in equity (including a decree of specific performance and/or other injunctive relief), and nothing herein shall limit the right of the Holder right to pursue actual damages for any failure by the Company to comply with the terms of this Warrant. The Company acknowledges that a breach by it of its obligations hereunder will cause irreparable harm to the Holder and that the remedy at law for any such breach may be inadequate. The Company therefore agrees that, in the event of any such breach or threatened breach, the holder of this Warrant shall be entitled, in addition to all other available remedies, to an injunction restraining any breach, without the necessity of showing economic loss and without any bond or other security being required.

14. TRANSFER. This Warrant may be offered for sale, sold, transferred or assigned in accordance with applicable law without the consent of the Company.

15. CERTAIN DEFINITIONS. For purposes of this Warrant, the following terms shall have the following meanings:

(a) “1933 Act” means the Securities Act of 1933, as amended.

(b) “Black Scholes Value” means the value of this Warrant based on the Black and Scholes Option Pricing Model obtained from the “OV” function on Bloomberg determined as of the day of closing of the applicable Fundamental Transaction for pricing purposes and reflecting (i) a risk-free interest rate corresponding to the U.S. Treasury rate for a period equal to the remaining term of this Warrant as of such date of request, (ii) an expected volatility equal to the greater of 60% and the 100 day volatility obtained from the HVT function on Bloomberg as of the day immediately following the public announcement of the applicable Fundamental Transaction and (iii) the underlying price per share used in such calculation shall be the sum of the price per share being offered in cash, if any, plus the value of any non-cash consideration, if any, being offered in the Fundamental Transaction.

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(c) “Bloomberg” means Bloomberg Financial Markets.

(d) “Business Day” means any day other than Saturday, Sunday or other day on which commercial banks in The City of New York are authorized or required by law to remain closed.

(e) “Closing Sale Price” means, for any security as of any date, the last closing trade price for such security on the Principal Market, as reported by Bloomberg, or, if the Principal Market begins to operate on an extended hours basis and does not designate the closing trade price then the last trade price of such security prior to 4:00:00 p.m., New York time, as reported by Bloomberg, or, if the Principal Market is not the principal securities exchange or trading market for such security, the last trade price of such security on the principal securities exchange or trading market where such security is listed or traded as reported by Bloomberg, or if the foregoing do not apply, the last trade price of such security in the over-the-counter market on the electronic bulletin board for such security as reported by Bloomberg, or, if no last trade price is reported for such security by Bloomberg, the average of the bid prices, or the ask prices, respectively, of any market makers for such security as reported in the “pink sheets” by Pink Sheets LLC (formerly the National Quotation Bureau, Inc.). If the Closing Sale Price cannot be calculated for a security on a particular date on any of the foregoing bases, the Closing Sale Price of such security on such date shall be the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair market value of such security, then such dispute shall be resolved pursuant to Section 12. All such determinations to be appropriately adjusted for any stock dividend, stock split, stock combination or other similar transaction during the applicable calculation period.

(f) “Common Stock” means (i) the Company’s shares of Common Stock, par value $0.001 per share, and (ii) any share capital into which such Common Stock shall have been changed or any share capital resulting from a reclassification of such Common Stock.

(g) “Common Stock Deemed Outstanding” means, at any given time, the number of shares of Common Stock actually outstanding at such time, plus the number of shares of Common Stock deemed to be outstanding pursuant to Sections 2(a)(i) and 2(a)(ii) hereof regardless of whether the Options or Convertible Securities are actually exercisable at such time, but excluding any shares of Common Stock owned or held by or for the account of the Company or issuable upon exercise of the SPA Warrants.

(h) “Convertible Securities” means any stock or securities (other than Options) directly or indirectly convertible into or exercisable or exchangeable for shares of Common Stock.

(i) “Eligible Market” means the Principal Market, The New York Stock Exchange, Inc., The NASDAQ Global Select Market or The NASDAQ Capital Market.

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(j) “Expiration Date” means thirty six (36) months after the applicable Initial Exercise Eligibility Date or, if such date falls on a day other than a Business Day or on which trading does not take place on the Principal Market (a “Holiday”), the next date that is not a Holiday.

(k) “Fundamental Transaction” means that the Company shall, directly or indirectly, in one or more related transactions, (i) consolidate or merge with or into (whether or not the Company is the surviving corporation) another Person or Persons, if the holders of the Voting Stock (not including any shares of Voting Stock held by the Person or Persons making or party to, or associated or affiliated with the Persons making or party to, such consolidation or merger) immediately prior to such consolidation or merger shall hold or have the right to direct the voting of less than 50% of the Voting Stock or such voting securities of such other surviving Person immediately following such transaction, or (ii) sell, assign, transfer, convey or otherwise dispose of all or substantially all of the properties or assets of the Company to another Person, or (iii) allow another Person to make a purchase, tender or exchange offer that is accepted by the holders of more than the 50% of the outstanding shares of Voting Stock (not including any shares of Voting Stock held by the Person or Persons making or party to, or associated or affiliated with the Persons making or party to, such purchase, tender or exchange offer), or (iv) consummate a stock purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with another Person whereby such other Person acquires more than the 50% of the outstanding shares of Voting Stock (not including any shares of Voting Stock held by the other Person or other Persons making or party to, or associated or affiliated with the other Persons making or party to, such stock purchase agreement or other business combination), (v) reorganize, recapitalize or reclassify its Common Stock or (vi) any “person” or “group” (as these terms are used for purposes of Sections 13(d) and 14(d) of the Securities Exchange Act of 1934, as amended) is or shall become the “beneficial owner” (as defined in Rule 13d-3 under the Securities Exchange Act of 1934, as amended), directly or indirectly, of 50% of the aggregate ordinary voting power represented by issued and outstanding Common Stock.

(l) “Initial Exercise Eligibility Date” means (i) with respect to the number of Warrant Shares specified in column (2) of Schedule I attached hereto, the date specified in column (1) opposite such number of Warrant Shares and (ii) with respect to any portion of this Warrant not previously exercisable, the date when all Series A Warrants have been exercised.

(m) “Maximum Eligibility Number” means initially zero and shall be increased by an amount equal to the aggregate number of the Holder’s Series A Warrants exercised during the period from and after the Issuance Date as indicated in column (2) of Schedule I attached hereto, such that the Maximum Eligibility Number at any given time shall be as set forth in column (3) of such Schedule I; provided; that the Maximum Eligibility Number shall be [                    ] on the date when all Series A Warrants have been exercised as adjusted for any stock dividend, stock split, stock combination, reclassification or similar transactions.

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(n) “Options” means any rights, warrants or options to subscribe for or purchase shares of Common Stock or Convertible Securities.

(o) “Parent Entity” of a Person means an entity that, directly or indirectly, controls the applicable Person and whose common stock or equivalent equity security is quoted or listed on an Eligible Market, or, if there is more than one such Person or Parent Entity, the Person or Parent Entity with the largest public market capitalization as of the date of consummation of the Fundamental Transaction.

(p) “Person” means an individual, a limited liability company, a partnership, a joint venture, a corporation, a trust, an unincorporated organization, any other entity and a government or any department or agency thereof.

(q) “Principal Market” means The NASDAQ Global Market.

(r) “Required Holders” means the holders of the SPA Warrants representing at least a majority of shares of Common Stock underlying the SPA Warrants then outstanding.

(s) “Series A Warrants” means the Series A Warrants issued pursuant to the Securities Purchase Agreement.

(t) “SPA Securities” means the Notes issued pursuant to the Securities Purchase Agreement.

(u) “Successor Entity” means the Person (or, if so elected by the Required Holders, the Parent Entity) formed by, resulting from or surviving any Fundamental Transaction or the Person (or, if so elected by the Required Holders, the Parent Entity) with which such Fundamental Transaction shall have been entered into.

(v) “Trading Day” means any day on which the Common Stock are traded on the Principal Market, or, if the Principal Market is not the principal trading market for the Common Stock, then on the principal securities exchange or securities market on which the Common Stock are then traded; provided that “Trading Day” shall not include any day on which the Common Stock are scheduled to trade on such exchange or market for less than 4.5 hours or any day that the Common Stock are suspended from trading during the final hour of trading on such exchange or market (or if such exchange or market does not designate in advance the closing time of trading on such exchange or market, then during the hour ending at 4:00:00 p.m., New York time).

(w) “Voting Stock” of a Person means capital stock of such Person of the class or classes pursuant to which the holders thereof have the general voting power to elect, or the general power to appoint, at least a majority of the board of directors, managers or trustees of such Person (irrespective of whether or not at the time capital stock of any other class or classes shall have or might have voting power by reason of the happening of any contingency).

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(x) “Weighted Average Price” means, for any security as of any date, the dollar volume-weighted average price for such security on the Principal Market during the period beginning at 9:30:01 a.m., New York City time, and ending at 4:00:00 p.m., New York City time, as reported by Bloomberg through its “Volume at Price” function or, if the foregoing does not apply, the dollar volume-weighted average price of such security in the over-the-counter market on the electronic bulletin board for such security during the period beginning at 9:30:01 a.m., New York City time, and ending at 4:00:00 p.m., New York City time, as reported by Bloomberg, or, if no dollar volume-weighted average price is reported for such security by Bloomberg for such hours, the average of the highest closing bid price and the lowest closing ask price of any of the market makers for such security as reported in the “pink sheets” by Pink Sheets LLC (formerly the National Quotation Bureau, Inc.). If the Weighted Average Price cannot be calculated for such security on such date on any of the foregoing bases, the Weighted Average Price of such security on such date shall be the fair market value as mutually determined by the Company and the Required Holders. If the Company and the Required Holders are unable to agree upon the fair market value of such security, then such dispute shall be resolved pursuant to Section 12 with the term “Weighted Average Price” being substituted for the term “Exercise Price.” All such determinations shall be appropriately adjusted for any share dividend, share split or other similar transaction during such period.

[Signature Page Follows]

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IN WITNESS WHEREOF, the Company has caused this Warrant to Purchase Common Stock to be duly executed as of the Issuance Date set out above.

Acknowledged and agreed with respect to Section 1(h):

EXHIBIT A

EXERCISE NOTICE

TO BE EXECUTED BY THE REGISTERED HOLDER TO EXERCISE THIS

WARRANT TO PURCHASE COMMON STOCK

NANOGEN, INC.

The undersigned holder hereby exercises the right to purchase                                          of the shares of Common Stock (“Warrant Shares”) of Nanogen, Inc., a Delaware corporation (the “Company”), evidenced by the attached Warrant to Purchase Common Stock (the “Warrant”). Capitalized terms used herein and not otherwise defined shall have the respective meanings set forth in the Warrant.

1. Form of Exercise Price. The Holder intends that payment of the Exercise Price shall be made as:

                     a “Cash Exercise” with respect to                                          Warrant Shares; and/or

                     a “Cashless Exercise” with respect to                                          Warrant Shares.

2. Payment of Exercise Price. In the event that the holder has elected a Cash Exercise with respect to some or all of the Warrant Shares to be issued pursuant hereto, the holder shall pay the Aggregate Exercise Price in the sum of $                                         to the Company in accordance with the terms of the Warrant.

3. Delivery of Warrant Shares. The Company shall deliver to the holder                      Warrant Shares in accordance with the terms of the Warrant.

Date:                  ,         

ACKNOWLEDGMENT

The Company hereby acknowledges this Exercise Notice and hereby directs Computershare Investor Services to issue the above indicated number of shares of Common Stock in accordance with the Transfer Agent Instructions dated August     , 2007 from the Company and acknowledged and agreed to by Computershare Investor Services.

SCHEDULE I