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                                                                    Exhibit 10.9

NEITHER THIS WARRANT NOR THE SHARES OF STOCK ISSUABLE UPON EXERCISE HEREOF, HAVE
BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. NO SALE, TRANSFER
OR OTHER DISPOSITION OF THIS WARRANT OR SAID SHARES MAY BE EFFECTED WITHOUT (i)
AN EFFECTIVE REGISTRATION STATEMENT RELATED THERETO, (ii) AN OPINION OF COUNSEL
FOR THE HOLDER, REASONABLY SATISFACTORY OR (iii) RECEIPT OF A NO-ACTION LETTER
FROM THE SECURITIES AND EXCHANGE COMMISSION TO THE EFFECT THAT REGISTRATION
UNDER THE ACT IS NOT REQUIRED.

Shares Issuable Upon Exercise:  Up to 50,000

                        WARRANT TO PURCHASE COMMON STOCK
                                       OF
                                  NANOGEN, INC.

                             EXPIRES APRIL 12, 2007

     THIS CERTIFIES THAT, for value received, GeneType AG, a wholly-owned
Australian corporate subsidiary of Genetic Technologies Limited, having an
office at 60-66 Hanover Street, Fitzroy, Victoria 3065, Australia ("GeneType")
or its registered assigns (GeneType or its registered assigns shall hereinafter
be referred to as "HOLDER"), is entitled, subject to the terms and conditions
set forth below, to subscribe for and purchase up to 50,000 shares (as adjusted
pursuant to the provisions hereof, the "SHARES") of the fully paid and
nonassessable common stock ("COMMON STOCK"), par value $.001 per share, of
Nanogen, Inc., a Delaware corporation (the "COMPANY") at an exercise price per
share of $4.10 (such price and such other price as shall result, from time to
time, from adjustments specified herein is referred to as the "EXERCISE PRICE").
The term "WARRANT" as used herein shall mean this Warrant, and any warrants
delivered in substitution or exchange therefor as provided herein. This Warrant
is being issued pursuant to the License Agreement between GeneType and the
Company, dated April 12, 2002 (the "LICENSE AGREEMENT")

     1.   TERM. Subject to the terms and conditions set forth herein, this
Warrant is exercisable, in whole or in part, at any time and from time to time
from and after April 12, 2002 (the "GRANT DATE") and prior to 5:00 p.m., Pacific
Standard Time on the date above that is the fifth anniversary of the Grant Date
(the "EXERCISE PERIOD") and shall be void thereafter.

     2.   METHOD OF EXERCISE; NET ISSUE EXERCISE.

     (a)  METHOD OF EXERCISE; PAYMENT; ISSUANCE OF NEW WARRANT. This Warrant may
be exercised by the Holder, by either, at the election of the Holder, (i) the
surrender of this Warrant to the Company (with the Notice of Exercise attached
hereto as Exhibit A-1 duly completed and executed on behalf of the Holder), at
the principal office of the Company and by payment to the Company, for the
account of the Company, by check or wire transfer of immediately available funds
to a bank account specified by the Company, of an amount equal to the Exercise
Price multiplied by the number of Shares then being purchased as specified in
the Exercise Form in

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lawful money of the United States of America or (ii) if in connection with a
registered public offering of the Company's securities, the surrender of this
Warrant (with the Notice of Exercise attached hereto as Exhibit A-2 duly
completed and executed on behalf of Holder) at the principal office of the
Company and by payment to the Company, for the account of the Company, by check,
wire transfer of immediately available funds to a bank account specified by the
Company or from the proceeds of the sale of Shares to be sold by the Holder in
such public offering of an amount equal to the Exercise Price multiplied by the
number of Shares then being purchased as specified in the Exercise Form in
lawful money of the United States of America. The Company agrees that such
Shares shall be deemed to be issued to the Holder as the record holder of such
Shares as of the close of business on the date on which this Warrant shall have
been surrendered and payment made for the Shares as aforesaid (the "EXERCISE
DATE"). A stock certificate or certificates for the Shares specified in the
Notice of Exercise shall be delivered to the Holder as soon as practicable, and
in any event within 30 days thereafter. If this Warrant shall have been
exercised only in part, the Company shall, at the time of delivery of the stock
certificate or certificates, deliver to the Holder a new Warrant evidencing the
rights to purchase the remaining Shares, which new Warrant shall in all other
respects be identical with this Warrant. No adjustments shall be made on Shares
issuable on the exercise of this Warrant for any cash dividends paid or payable
to holders of record of common stock prior to the date as of which the Holder
shall be deemed to be the record holder of such Shares. However, the number of
Shares shall be adjusted to reflect any stock dividend, stock split or other
conversion of the number of shares of the Company into a different number of
shares, however denominated, as described in Section 3.

     (b)  NET ISSUE EXERCISE. In lieu of exercising this Warrant pursuant to
Section 2(a), the Holder may elect to receive, without payment by the Holder of
any additional consideration, shares equal to the value of this Warrant or any
portion hereof by the surrender of this Warrant or such portion to the Company
(with the Notice of Exercise attached hereto as Exhibit A-1 hereto duly
completed and executed) at the principal office of the Company. Thereupon, the
Company shall issue to the Holder such number of fully paid and nonassessable
shares of Common Stock as is computed using the following formula:

                                   X = Y (A-B)
                                       -------
                                          A

               where

                    X  =  the number of shares to be issued to the Holder
                          pursuant to this Section 2(b).

                    Y  =  the number of shares of common stock otherwise
                          issuable under this Warrant (as adjusted to the date
                          of such calculation).

                    A  =  the closing stock price of one share of the Company's
                          common stock as reported by the Nasdaq National Market
                          the business day immediately prior to the Exercise.

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                    B  =  the Exercise Price in effect under this Warrant at the
                          time the net issue election is made pursuant to this
                          Section 2(b).

     3.   ADJUSTMENT OF WARRANT PRICE AND NUMBER OF SHARES. The number and kind
of securities purchasable upon the exercise of the Warrant and the Warrant Price
shall be subject to adjustment from time to time upon the occurrence of certain
events, as follows:

     (a)  RECLASSIFICATION OR MERGER. In case of any reclassification, change or
conversion of securities of the class issuable upon exercise of this Warrant
(other than a change in par value, or from par value top no par value, or from
no par value to par value, or as a result of a subdivision or combination), or
in case of any merger of the Company with or into another corporation (other
than a merger with another corporation in which the Company is a continuing
corporation and which does not result in any reclassification or change of
outstanding securities issuable upon exercise of this Warrant), or in case of
any sale of all or substantially all of the assets of the Company, the Company,
or such successor or purchasing corporation, as the case may be, shall execute a
new Warrant) providing that the Holder of this Warrant shall have the right to
exercise such new Warrant and upon such exercise to receive, in lieu of each
share of Common Stock theretofore issuable upon exercise of this Warrant, the
kind and amount of shares of stock, other securities, money and property
receivable upon such reclassification, change or merger by a holder of one share
of Common Stock. Such new Warrant shall provide for adjustments that shall be as
nearly equivalent as may be practicable to the adjustments provided for in this
Section 3. The provisions of this Section 3(a) shall similarly apply to
successive reclassification, changes, mergers and transfers.

     (b)  SUBDIVISIONS OR COMBINATION OF SHARES. If the Company at any time
while this Warrant remains outstanding and unexpired shall subdivide or combine
its Common Stock, the Warrant Price and the number of shares issuable upon
exercise hereof shall be proportionately adjusted.

     (c)  STOCK DIVIDENDS. If the Company at any time while this Warrant is
outstanding and unexpired shall pay a dividend payable in shares of Common Stock
(except any distribution specifically provided for in Sections 3 (a) and (b)),
then the Warrant Price shall be adjusted, from and after the date of
determination of stockholders entitled to receive such dividend or distribution,
to that price determined by multiplying the Warrant Price in effect immediately
prior to such date of determination by a fraction (i) the numerator of which
shall be the total number of shares of Common Stock outstanding immediately
prior to such dividend or distribution, and (ii) the denominator of which shall
immediately after such dividend or distribution and the number of Shares subject
to this Warrant against impairment.

     (d)  NO IMPAIRMENT. The Company will not, by amendment of its Certificate
of Incorporation or through any reorganization, recapitalization, transfer of
assets, consolidation, merger, 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 to be observed or performed hereunder by the Company, but will
at all times in good faith assist in the carrying out of all the provisions

                                       -3-
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of this Section 3 and in the taking of all such actions as may be necessary or
appropriate in order to protect the rights of the holder of this warrant against
impairment.

     (e)  NOTICES OF RECORD DATE. In any event in any taking of the Company of a
record of its stockholders for the purpose of determining stockholders who are
entitled to receive payment of any dividend (other than cash dividend) or other
distribution, any right to subscribe for, purchase or otherwise acquire any
share of any class or any other securities or property, or to receive any other
right, or for the purpose of determining stockholders who are entitled to vote
in connection with any proposed merger or consolidation of the Company with or
into any other corporation, or any proposed sale, lease or conveyance of all or
substantially all of the assets of the Company, or any proposed liquidation,
dissolution or winding up of the Company, the Company shall mail to the Holder
of the Warrant, at least 20 days prior to the date specified therein, a notice
specifying the date on which any such record is to be taken for the purpose of
such dividend, distribution or right, and the amount and character of such
dividend, distribution or right.

     4.   NOTICE OF ADJUSTMENTS. Whenever the Warrant Price shall be adjusted
pursuant to the provisions hereof, the Company shall within 20 days of such
adjustment deliver a certificate signed by its chief financial officer to the
registered holder(s) hereof setting forth, in reasonable detail, the event
requiring the adjustment, the amount of the adjustment, the method by which such
adjustment was calculated, and the Warrant Price after giving effect to such
adjustment.

     5.   NO FRACTIONAL SHARES OR SCRIP. No fractional shares or scrip
representing fractional shares shall be issued upon the exercise of this
Warrant. In lieu of any fractional share to which the Holder would otherwise be
entitled, the Company shall make a cash payment equal to the Exercise Price
multiplied by such fraction.

     6.   REPLACEMENT OF WARRANT. On receipt 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, on delivery of an indemnity
agreement reasonably satisfactory in form and substance to the Company or, in
the case of mutilation, on surrender and cancellation of this Warrant, the
Company at its expense shall execute and deliver, in lieu of this Warrant, a new
warrant of like tenor and amount.

     7.   RIGHTS OF STOCKHOLDERS. The Holder of this Warrant shall not be
entitled to vote or receive dividends or be deemed the holder of common stock
nor shall anything contained herein be construed to confer upon the Holder, as
such, any of the rights of a stockholder of the Company or any right to vote for
the election of directors or upon any matter submitted to stockholders at any
meeting thereof, or to give or withhold consent to any corporate action (whether
upon any recapitalization, issuance of stock, reclassification of stock, change
of par value, or change of stock to no par value, consolidation, merger,
conveyance, or otherwise) or to receive notice of meetings, or to receive
dividends or subscription rights or otherwise until the Warrant shall have been
exercised as provided herein.

                                       -4-
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     8.   TRANSFER OF WARRANT.

     (a)  WARRANT REGISTER. The Company will maintain a register (the "WARRANT
REGISTER") containing the names and addresses of the Holder or Holders. Any
Holder of this Warrant or any portion thereof may change his address as shown on
the Warrant Register by written notice to the Company requesting such change.
Any notice or written communication required or permitted to be given to the
Holder may be delivered or given by mail to such Holder as shown on the Warrant
Register and at the address shown on the Warrant Register. Until this Warrant is
transferred on the Warrant Register of the Company, the Company may treat the
Holder as shown on the Warrant Register as the absolute owner of this Warrant
for all purposes, notwithstanding any notice to the contrary.

     (b)  WARRANT AGENT. The Company may, by written notice to the Holder,
appoint an agent for the purpose of maintaining the Warrant Register referred to
in Section 8(a) above, issuing the common stock, exchanging this Warrant,
replacing this Warrant, or any or all of the foregoing. Thereafter, any such
registration, issuance, exchange, or replacement, as the case may be, shall be
made at the office of such agent.

     (c)  TRANSFERABILITY AND NONNEGOTIABILITY OF WARRANT. This Warrant may not
be transferred or assigned in whole or in part without compliance with all
applicable federal and state securities laws by the transferor and the
transferee (including the delivery of investment representation letters and
legal opinions reasonably satisfactory to the Company, if such are requested by
the Company). Notwithstanding the foregoing, no investment representation letter
or opinion of counsel shall be required for any transfer of this Warrant (or any
portion thereof) or any shares of common stock issued upon exercise hereof (i)
in compliance with Rule 144 or Rule 144A of the Act, or (ii) by gift, will or
intestate succession by the Holder to his or her spouse or lineal descendants or
ancestors or any trust for any of the foregoing; provided that in each of the
foregoing cases the transferee agrees in writing to be subject to the terms of
this Section 8(c). In addition, if the holder of the Warrant (or any portion
thereof) or any common stock issued upon exercise hereof delivers to the Company
an unqualified opinion of counsel that no subsequent transfer of such Warrant or
common stock shall require registration under the Act, the Company shall, upon
such contemplated transfer, promptly deliver new documents/certificates for such
Warrant or common stock that do not bear the legend set forth in Section
8(e)(ii) below. Subject to the provisions of this Warrant with respect to
compliance with the Securities Act of 1933, as amended (the "ACT"), title to
this Warrant may be transferred by endorsement (by the Holder executing the
Assignment Form attached hereto as Exhibit B) and delivery in the same manner as
a negotiable instrument transferable by endorsement and delivery.

     (d)  EXCHANGE OF WARRANT UPON A TRANSFER. On surrender of this Warrant for
exchange, properly endorsed on the Assignment Form and subject to the provisions
of this Warrant with respect to compliance with the Act and with the limitations
on assignments and transfers and contained in this Section 8, the Company shall
issue to or on the order of the Holder a new warrant or warrants of like tenor,
in the name of the Holder or as the Holder (on payment by the Holder of any
applicable transfer taxes) may direct, for the number of shares issuable upon
exercise hereof.

                                       -5-
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     (e)  COMPLIANCE WITH SECURITIES LAWS.

          (i)   The Holder of this Warrant represents and warrants to the
     Company that it is an accredited investor under the Act. The Holder
     represents and warrants to the Company that it has all of the information
     necessary for it to evaluate an investment in the Company's securities.

          (ii)  The Holder of this Warrant, by acceptance hereof, acknowledges
     that this Warrant and the shares of common stock to be issued upon exercise
     hereof are being acquired solely for the Holder's own account and not as a
     nominee for any other party, and for investment, and that the Holder will
     not offer, sell or otherwise dispose of this Warrant or any shares of
     common stock to be issued upon exercise hereof except under circumstances
     that will not result in a violation of the Act or any applicable state
     securities laws. Upon the exercise of this Warrant, the Holder shall, if
     requested by the Company, confirm in writing, in a form satisfactory to the
     Company, that the shares of common stock so purchased are being acquired
     solely for the Holder's own account and not as a nominee for any other
     party, for investment, and not with a view toward distribution or resale.

          (iii) This Warrant and all shares of common stock issued upon exercise
     hereof shall be stamped or imprinted with a legend in substantially the
     following form (in addition to any legend required by state securities
     laws):

          "NEITHER THIS WARRANT NOR THE SHARES OF STOCK ISSUABLE UPON EXERCISE
          HEREOF, HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
          AMENDED. NO SALE, TRANSFER OR OTHER DISPOSITION OF THIS WARRANT OR
          SAID SHARES MAY BE EFFECTED WITHOUT (i) AN EFFECTIVE REGISTRATION
          STATEMENT RELATED THERETO, (ii) AN OPINION OF COUNSEL FOR THE HOLDER,
          REASONABLY SATISFACTORY OR (iii) RECEIPT OF A NO-ACTION LETTER FROM
          THE SECURITIES AND EXCHANGE COMMISSION TO THE EFFECT THAT REGISTRATION
          UNDER THE ACT IS NOT REQUIRED."

          (iv)  The Company agrees to remove promptly, upon the request of the
     holder of this Warrant and Securities issuable upon exercise of the
     Warrant, the legend set forth in Section 8(e)(ii) above from the
     documents/certificates for such securities upon full compliance with this
     Agreement and Rules 144 and 144A.

     9.   RESERVATION OF STOCK. The Company covenants that, the Company will
reserve from its authorized and unissued common stock a sufficient number of
shares to provide for the issuance of common stock upon the exercise of this
Warrant (including any adjustment in the number of Shares pursuant to Section
2(a)). The Company further covenants that all shares that may be issued upon the
exercise of rights represented by this Warrant and payment of the Exercise
Price, all as set forth herein, will be free from all taxes, liens and charges
in respect of the issue thereof (other than taxes in respect of any transfer
occurring contemporaneously or

                                       -6-
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otherwise specified herein). The Company agrees that its issuance of this
Warrant shall constitute full authority to its officers who are charged with the
duty of executing stock certificates to execute and issue the necessary
certificates for shares of common stock upon the exercise of this Warrant.

     10.  COMPANY REGISTRATION.

     (a)  If (but without the obligation to do so) the Company proposes to
register any of its Common Stock under the Act in connection with the public
offering of such securities solely for cash (other than a registration relating
solely of the sale of securities to participants in any Company stock option,
stock purchase or retirement plan), the Company shall, at each such time,
promptly give to Holder written notice of such registration in the form attached
hereto as Exhibit A-2. Upon the written request of Holder given within twenty
(20) days after mailing of such notice by the Company to Holder's latest address
contained in the Warrant Registry, the Company shall, subject to the provisions
of Section 10(b), cause to be registered under the Act all of the Shares that
Holder has requested to be registered.

     (b)  Holder shall only be able to participate in such registration if it
accepts the terms and conditions of such underwriting as agreed upon between the
Company and its underwriters and Holder agrees that it will abide by the
determination of the underwriters as to the quantity of Holder's Shares to be
offered in the underwriting so as not to jeopardize the success of the offering
by the Company. If the underwriters determine that not all of the Shares will be
included in an offering, Holder may request inclusion in the next public
offering of the Company's Common Stock pursuant to the provisions of Section
10(a).

     11.  EXPENSES OF REGISTRATION. All Registration Expenses (as defined
herein) incurred in connection with any registration, qualification or
compliance pursuant to Section 10 hereof and reasonable fees of one counsel for
Holder shall be borne by the Company. All Selling Expenses (as defined herein)
relating to securities so registered shall be borne by the holders of such
securities PRO RATA on the basis of the number of shares of securities so
registered on their behalf. "REGISTRATION EXPENSES" shall mean all expenses
incurred in effecting any registration pursuant to this Warrant, including,
without limitation, all registration, qualification, and filing fees, printing
expenses, escrow fees, fees and disbursements of counsel for the Company, fees
and disbursements of one special counsel for the selling stockholders, blue sky
fees and expenses, accounting fees and expenses of any regular or special audits
incident to or required by any such registration, but shall not include Selling
Expenses and fees and disbursements of additional counsel for the stockholders.
Registration Expenses do not include the compensation of regular employees of
the Company, which shall be paid in any event by the Company. "SELLING EXPENSES"
shall mean all underwriting discounts and selling commissions applicable to the
sale of Shares and fees and disbursements of counsel for any Holder (other than
the fees and disbursements of counsel included in Registration Expenses).

     12.  AMENDMENTS. This Warrant and any term hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of such change, waiver, discharge or termination is
sought.

                                       -7-
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     13.  MISCELLANEOUS.

     (a)  GOVERNING LAW. This Warrant shall constitute a contract under the laws
of the State of California and for all purposes shall be construed in accordance
with and governed by the laws of said state, without regard to the conflicts of
law provisions thereof.

     (b)  ATTORNEYS' FEES; LITIGATION EXPENSES. In the event of a dispute with
regard to the interpretation of this Warrant, the prevailing party may collect
the cost of attorney's fees, litigation expenses or such other expenses as may
be incurred in the enforcement of the prevailing party's rights hereunder.

     (c)  TRANSFER RESTRICTIONS. The rights to cause the Company to register
securities granted to a Holder by the Company under Section 10 may be
transferred or assigned by Holder only to a transferee or assignee of not less
than 25,000 Shares, provided that the Company is given written notice at the
time of or within a reasonable time after such transfer or assignment, stating
the name and address of the transferee or assignee and identifying the
securities with respect to which such registration rights are being transferred
or assigned, and, provided further, that the transferee or assignee of such
rights assumes the obligations of such Holder under this Warrant.

     (d)  EXPIRATION DATE. This Warrant shall be exercisable as provided for
herein, except that in the event that the expiration date of this Warrant shall
fall on a Saturday, Sunday or United States federally recognized Holiday, this
expiration date for this Warrant shall be extended to 5:00 p.m. Pacific standard
time on the business day following such Saturday, Sunday or recognized Holiday.

     IN WITNESS WHEREOF, the Company has caused this Warrant to be executed by
its one of its officers thereunto duly authorized.

     Dated: April 12, 2002

                                           NANOGEN, INC., a Delaware corporation


                                           By /s/ V. RANDY WHITE
                                              ------------------
                                              V. Randy White
                                              Chief Executive Officer

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                                   EXHIBIT A-1
                               NOTICE OF EXERCISE

To:  Nanogen, Inc.                                            Date: ____________
     10398 Pacific Center Court
     San Diego, CA  92121
     Attn:  Vice President, Legal Affairs

Dear Sir:

     (1)  The undersigned hereby elects to purchase shares of common stock of
Nanogen, Inc. (the "COMPANY") either (check box):

                pursuant to the terms of Section 2(a) of the attached Warrant,
          and tenders herewith payment of the purchase price for such shares in
          full or

                pursuant to the net issue provisions of Section 2(b) of the
          Warrant and surrenders the right to purchase _______ shares of Common
          Stock pursuant to the Warrant.

     (2)  In exercising this Warrant, the undersigned hereby confirms and
acknowledges that the shares of common stock to be issued upon conversion
thereof are being acquired solely for the account of the undersigned and not as
a nominee for any other party, or for investment, and that the undersigned will
not offer, sell or otherwise dispose of any such shares of common stock except
under circumstances that will not result in a violation of the Securities Act of
1933, as amended, or any applicable state securities laws.

     (3)  Please issue a certificate or certificates representing said shares of
common stock in the name of the undersigned or in such other name as is
specified below:


                                        ----------------------------------------
                                        (Name)

                                       -9-
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     (4)  Please issue a new Warrant for the unexercised portion of the attached
Warrant in the name of the undersigned or in such other name as is specified
below:


                                        ----------------------------------------
                                        (Name)


                                        ----------------------------------------
                                        Signature

                                        Address:
                                                 -------------------------------

                                                 -------------------------------

                                      -10-
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                                   EXHIBIT A-2
                               NOTICE OF EXERCISE
                           (PURSUANT TO REGISTRATION)

To:  Nanogen, Inc.                                              Date: __________
     10398 Pacific Center Court
     San Diego, CA  92121
     Attn:  Vice President, Legal Affairs

Dear Sir:

     (1)  Contingent upon and effective immediately prior to the closing (the
"CLOSING") of the Company's public offering contemplated by the Registration
Statement on Form S-_, filed with the Securities and Exchange Commission on
__________________________, 20__, the undersigned hereby elects to purchase
____________________ shares of Common Stock of the Company (or such lesser
number of shares as may be sold on behalf of the undersigned at the Closing)
pursuant to the terms of the attached Warrant.

     (2)  Please deliver to the custodian for the selling stockholders a stock
certificate representing such ________ shares.

     (3)  The undersigned has instructed the custodian for the selling
stockholders to deliver to the Company $__________________ or, if less, the net
proceeds due the undersigned from the sale of shares in the aforesaid public
offering. If such net proceeds are less than the purchase price for such shares,
the undersigned agrees to deliver the difference to the Company prior to the
Closing.

     (4)  Please issue a certificate or certificates representing said shares of
common stock in the name of the undersigned or in such other name as is
specified below:


                                        ----------------------------------------
                                        (Name)

                                      -11-
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     (5)  Please issue a new Warrant for the unexercised portion of the attached
Warrant in the name of the undersigned or in such other name as is specified
below:


                                        ----------------------------------------
                                        (Name)


                                        ----------------------------------------
                                        Signature

                                        Address:
                                                 -------------------------------

                                                 -------------------------------


                                      -12-
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                                    EXHIBIT B
                                 ASSIGNMENT FORM

To:  Nanogen, Inc.                                              Date: __________
     10398 Pacific Center Court
     San Diego, CA  92121
     Attn:  Vice President, Legal Affairs

Dear Sir:

     FOR VALUE RECEIVED, the undersigned registered owner of this Warrant hereby
sells, assigns and transfers unto the Assignee named below all of the rights of
the undersigned under the within Warrant, with respect to the number of shares
of common stock set forth below:

Name of Assignee                 Address                      No. of Shares
------------------------------   ---------------------------  ------------------


and does hereby irrevocably constitute and appoint the Vice President, Legal
Affairs of Nanogen, Inc. (the "COMPANY") to make such transfer on the books of
the Company, maintained for the purpose, with full power of substitution in the
premises.

     The undersigned also represents that, by assignment hereof, the Assignee
acknowledges that this Warrant and the shares of stock to be issued upon
exercise hereof or conversion thereof are being acquired for investment and that
the Assignee will not offer, sell or otherwise dispose of this Warrant or any
shares of stock to be issued upon exercise hereof or conversion thereof except
under circumstances which will not result in a violation of the Securities Act
of 1933, as amended, or any applicable state securities laws. Further, the
Assignee has acknowledged that upon exercise of this Warrant, the Assignee
shall, if requested by the Company, confirm in writing, in a form satisfactory
to the Company, that the shares of stock so purchased are being acquired for
investment and not with a view toward distribution or resale.


                                        ----------------------------------------
                                        Signature (of Holder)

                                        Address:
                                                 -------------------------------

                                                 -------------------------------

                                      -13-