<Page>
                                                       Contribution Agreement  1

[Confidential Treatment Requested. Confidential portions of this Agreement have
been redacted and filed separately with the Commission.]

                             CONTRIBUTION AGREEMENT



between


Aventis Research & Technologies GmbH & Co KG
Industriepark Hochst, Building G 865 A,
65926 Frankfurt am Main
Germany


                                        - hereinafter referred to as "Aventis" -


and


Nanogen Inc.
10398 Pacific Court
San Diego, CA 92121
USA


                                        - hereinafter referred to as "Nanogen" -

and


Nanogen Recognomics GmbH
(former: WT Achtzehnte Verwaltungsgesellschaft mbH)
Industriepark Hochst, Building G 830
65926 Frankfurt am Main
Germany

                                            - hereinafter referred to as "J.V."-

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                                                       Contribution Agreement  2

DEFINITIONS

Unless the context shall otherwise require, the following terms shall have the
following meanings throughout this Agreement:

"Agreement" shall mean this Contribution Agreement.

"J.V. Business" shall mean (XXX).

"Contribution Date" shall mean (XXX), 24:00 hours.

"IPR" shall mean all trademarks, service marks, trade dress, logos, copyrights,
rights of authorship, all applications, registrations and renewals relating to
the preceding items, database rights, moral rights, inventions, rights of
inventorship, rights of publicity and privacy, trade secrets, know-how, rights
under unfair competition and unfair trade practices laws, and all other
worldwide intellectual and industrial property rights related thereto, existing
as of the Contribution Date and relating exclusively to the J.V. Business.

"Contracts" shall mean contracts, contract offers, permissions, concessions,
licenses, options to licenses, memberships, research and development agreements,
joint venture agreements and other legal relationships of Aventis existing as of
the Contribution Date and relating exclusively to the J.V. Business as listed in
EXHIBIT 6 of this Agreement, however, expressly excluding (1) the Collaborative
Research and Development Agreements between Hoechst Research & Technologies
Deutschland GmbH and Nanogen Inc. dated 3 December, 1998 and 27 September, 1999
which relate to separate and different research and development projects of
Aventis and (2) (XXX).

(XXX) - Confidential Information redacted and filed separately with the
        Commission

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                                                       Contribution Agreement  3

A.      CONTRIBUTION OF ASSETS AND PATENTS BY AVENTIS


SECTION 1      CONTRIBUTION OF ASSETS AND PATENTS TO THE J.V.

(1)     Pursuant to the provisions set forth below, Aventis hereby assigns and
        transfers to the J.V. effective as of the Contribution Date

        a)    any and all installations, technical facilities, equipment,
              vehicles, tools, software and machinery in the ownership of
              Aventis which - as of the Contribution Date - were used
              exclusively by or in the J.V. Business and which are located in
              Industriepark Hochst, Building G 830, 65926 Frankfurt am Main,
              Germany, in the rooms listed in EXHIBIT 1.

        b)    the entire operational, office and business equipment in the
              ownership of Aventis which - as of the Contribution Date - were
              used exclusively by or in the J.V. Business, including any and all
              files, records, operational data or other business documentation,
              customer lists, price calculations, supplier lists and advertising
              material as well as any and all documents, papers and items which
              relate exclusively to the J.V. Business.

        c)    The inventories of raw materials, work in process, finished goods,
              spare parts, service parts, tool, consumables, supplies and
              packaging materials held for use or manufactured exclusively in
              relation to the J.V. Business and located in the rooms listed in
              EXHIBIT 2.

        d)    any and all patents, patent disclosures, patent applications,
              including all provisionals, continuations (in whole or in part),
              divisionals, reissues, extensions, supplementary protection
              certificates, reexaminations and foreign counterparts thereof, as
              well as all inventions of employees of Aventis employed
              exclusively in the J.V. Business and on the Contribution Date
              registered with the relevant patent department of Aventis, all in
              the sole and exclusive ownership of Aventis, as listed in EXHIBIT
              3.

        e)    Aventis' ownership interest in any and all patents, patent
              disclosures, patent applications, including all provisionals,
              continuations (in whole or in part), divisionals, reissues,
              extensions, supplementary protection certificates,

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                                                       Contribution Agreement  4

              reexaminations and foreign counterparts thereof, as well as all
              jointly owned inventions by Aventis and Nanogen, as listed in
              EXHIBIT 4.

        f)    any and all IPR solely owned by Aventis and Aventis' ownership
              interest in IPR jointly owned by Aventis and Nanogen, to the
              extent possible listed in EXHIBIT 5.

              Aventis shall make available to the J.V. without undue delay after
              the Contribution Date all records, documents, files, results,
              plans kind other materials relating exclusively to know-how
              contributed to the J.V. as provided for in this Agreement which
              the J.V. requires to understand, assess and exploit such know-how.

        g)    pursuant to Section 2 below all Contracts as listed in EXHIBIT 6.

        The J.V. hereby accepts this assignment and transfer.

(2)     In case that the transfer of ownership pursuant to Section 1 subsection
        (1) of this Agreement should not be realized as per the Contribution
        Date, the transfer of ownership shall be substituted by the agreement
        that Aventis will hold these assets in cost-free bailment for the J.V.
        pursuant to Section 930 BGB (German Civil Code) and that after the
        Contribution Date, the J.V. shall at any time be entitled to take
        possession of such assets. In case of assets being in the possession of
        third parties, Aventis on the Contribution Date shall assign its claim
        for restoration of the property to the J.V.

(3)     Furthermore, the parties agree that the tangible assets exclusively used
        by Aventis for the J.V. Business shall nonetheless pass on to the J.V.
        even if such individual assets are not located in the rooms evidenced in
        EXHIBIT 1 and 2 or by company records of Aventis unless they are
        expressly excluded in this Agreement from being assigned and
        transferred. This shall also apply if any documents referenced herein
        are incomplete or, due to modifications which have already occurred or
        may occur, do not reflect the status as of the Contribution Date.

(4)     Aventis shall remain liable for any and all obligations arising from the
        ownership and possession of the assets transferred pursuant to this
        Agreement accruing before the Contribution Date and shall indemnify the
        J.V. for any and all

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                                                       Contribution Agreement  5

        liabilities, costs, charges, recourse or other risks arising out of
        these transferred assets and accruing before the Contribution Date.
        However, the J.V. shall be liable for any such obligations accruing
        after the Contribution Date.

SECTION 2      CONTRACTS

(1)     As per the Contribution Date, the J.V. herewith enters into all
        Contracts as listed in EXHIBIT 6 in lieu of Aventis. For the sake of
        clarification, the parties herewith agree that rights and obligations
        under the lease and service contract between Aventis and InfraServ GmbH
        & Co. Hochst KG will be dealt with separately.

(2)     As per the Contribution Date, Aventis hereby assigns any and all rights
        arising out of the Contracts to the J.V. The J.V. hereby accepts this
        assignment.

        As per the Contribution Date, the J.V. shall assume any and all
        obligations of Aventis arising out of the Contracts and occurring after
        the Contribution Date and shall indemnify Aventis for any and all
        liabilities, costs, charges, recourse or other risks arising out of the
        Contracts and occurring after the Contribution Date.

        Aventis shall remain liable for any and all obligations arising out of
        the Contracts and occurring before the Contribution Date and shall
        indemnify the J.V. for any and all liabilities, costs, charges, recourse
        or other risks arising out of the Contracts and occurring before the
        Contribution Date.

        However, the J.V. shall not be liable for any infringements, asserted
        infringements or other breaches of any Contract caused prior to the
        Contribution Date.


(3)     If required, Aventis will request of the respective third party to such
        Contract to be transferred to the J.V. to consent to the transfer of the
        respective Contract to the J.V.


        In case that the external assumption of the Contract to be transferred
        to the J.V. should not be possible or should be feasible at
        unproportional costs only or if both Aventis and the J.V. should be of
        the opinion that an external consent is not suitable, the J.V. shall
        internally assume the obligations resulting from this

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                                                       Contribution Agreement  6

        Contract. In such case, Aventis shall - to the extent legally
        permissible - externally exercise the corresponding legal position as
        fiduciary of the J.V.. The assumption of the external legal position
        shall be deemed to have occurred on the Contribution Date.


        Subject to prior written notice of the J.V. with a notice period of
        (XXX) year, Aventis shall be entitled to terminate the respective
        Contract which is continued on a fiduciary basis by giving notice
        pursuant to the respective notice period effective on the next possible
        termination date. Aventis shall not be liable in case any Contract
        cannot be continued or renewed or can be continued or renewed on new
        terms only between the J.V. and the third party.

SECTION 3      EMPLOYMENT AGREEMENTS

(1)     The parties are in agreement that as of the Contribution Date all
        employment agreements relating exclusively to the J.V. Business shall
        pass on to the J.V. pursuant to Section 613 a German Civil Code (BGB).
        The J.V. shall assume all rights and obligations under these employment
        agreements. This shall also include all rights and obligations resulting
        from the pension commitments existing at Aventis for the employees
        transferred to the J.V.

        A list of the employees employed exclusively in the J.V. Business is
        enclosed as EXHIBIT 7 which lists name and date of birth of the
        respective employees. The agreement between Aventis and the J.V.
        transferring the employment agreements to the J.V.
        ("Employment-Transfer-Agreement") is attached in EXHIBIT 8. For its
        remaining term, the "Personnel- and Socio-Political Transition Agreement
        for the Formation of the Strategic Management Holding Hoechst"
        (`Personal- und Sozialpolitische Uberleitungsvereinbarung zur Bildung
        der Strategischen Management Holding Hoechst") dated 20 January, 1997,
        attached as EXHIBIT 9, shall remain valid and applicable.

(2)     Aventis' works council - pursuant to the operating agreement
        ("Betriebsvereinbarung") as attached in EXHIBIT 10 - has agreed to the
        transfer of the employment agreements.

(XXX) - Confidential Information redacted and filed separately with the
        Commission

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                                                       Contribution Agreement  7

(3)     The J.V. shall hold harmless and indemnify Aventis against all
        liabilities accruing after the Contribution Date and resulting from the
        transferred employment agreements. Aventis shall hold harmless and
        indemnify the J.V. against all liabilities accruing up to the
        Contribution Date and resulting from the transferred employment
        agreements.

(4)     Aventis has notified the employees whose employment agreements pass on
        to the J.V. pursuant to Section 613 a of the German Civil Code (BGB) of
        the transfer to the J.V. as per the Contribution Date. All employees so
        notified have given their consent to the transfer of their employment
        agreements to the J.V.

SECTION 4      LIMITED ASSUMPTION OF OBLIGATIONS AND LIABILITES

(1)     Unless otherwise provided for in this Agreement, the J.V. shall not
        assume any obligations and liabilities of Aventis accrued before the
        Contribution Date. This shall in particular apply to warranty
        obligations arising out of supplies and services, to obligations to pay
        social insurance contributions and to obligations vis-a-vis associated
        enterprises if such liabilities accrued before the Contribution Date. It
        shall further apply to any and all taxes concerning the J.V. Business
        and its operations before the Contribution Date.

(2)     Aventis shall indemnify the J.V. for any obligations, liabilities,
        costs, charges, recourse or other risks in connection with any claims
        related to such non-assumed obligations and liabilities.

(3)     Aventis on the Contribution Date shall pay to the J.V. a sum equal to
        the pension reserves for the pension claims and other claims as provided
        for in the Employment~Transfer~Agreement attached as EXHIBIT 8.

        As of the Contribution Date, such reserves amount to the amounts listed
        in EXHIBIT 11. The parties agree to perform such adjustments which
        become necessary upon the final calculation of such reserves and to
        transfer the full amount of such reserves as per the Contribution Date
        after such Contribution Date.

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                                                       Contribution Agreement  8

(4)     Tax refund claims and liabilities concerning additional payment of taxes
        or liabilities with regard to additional social security payments until
        the Contribution Date shall remain with Aventis.

(5)     Aventis hereby warrants that no individual pension commitments exist.

SECTION 5      CONTRIBUTION OF CASH

Aventis on the Contribution Date shall contribute (i. e. pay) to the J.V. the
amount of US $ (XXX) (in words: US Dollars (XXX)) (XXX).

SECTION 6      VALUATION OF ASSETS ON THE TAX BALANCE SHEET, TURNOVER TAX

(1)     The assets contributed pursuant to Section 1 subsection (1) of this
        Agreement shall be valued at (XXX) value (XXX) in the accounts of the
        J.V. and booked as "other contributions" pursuant to Section 272
        subsection (2) No. 4 German Commercial Code (HGB) on the J.V.'s
        opening balance sheet.

(2)     In case that transfers under this Agreement are subject to VAT or become
        subject to VAT due to the waiver of a tax exemption, the J.V. will be
        liable for the resulting VAT against submission of a corresponding
        invoice.

SECTION 7      COOPERATION, PERFORMANCE OF SERVICES

(XXX) - Confidential Information redacted and filed separately with the
        Commission

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                                                       Contribution Agreement  9

(1)     The parties agree to give all declarations, to draw up all documents,
        and to undertake all other actions which are necessary for the transfer
        of the assets, liabilities, rights and obligations pursuant to this
        Agreement.

(2)     In case the consent of a shareholder, creditor, debtor, fiduciary or any
        other third party or any permissions under public law should be
        necessary for the transfer of the assets, liabilities, rights and
        obligations, the parties to this Agreement shall use their best efforts
        to obtain such consent or permission. If such consent or permission
        cannot be obtained or can be obtained at unproportional costs only,
        Section 2 subsection (3) shall apply with regard to the relationship
        between the parties.

(3)     The J.V. also shall receive all documents necessary for the assertion of
        the rights transferred under this Agreement. The J.V. shall store these
        books and other documents for Aventis during the legally required period
        of time, at least, however, until the respective tax audit of Aventis,
        if any, has become unappealable. The J.V. shall ensure that Aventis is
        able to inspect these documents and make copies of them.

        Documents which are kept in connection with the J.V. Business but which
        also relate to other departments of Aventis shall be kept by Aventis for
        the J.V. during the legally required period of time, at least, however,
        until the respective tax audit of J.V., if any, has become unappealable.
        Aventis shall ensure that J.V. is able to inspect these documents and
        make copies of them.

        In case of external tax investigations and litigation proceedings which
        concern the time period before the Contribution Date, the parties shall
        cooperate with regard to the access and exchange of information.

SECTION 8      WARRANTIES

(1)     Aventis warrants that,

        (a)   except for retentions of title customary in the respective trade,
              the transferred assets are unencumbered and free of any rights (as
              defined in Section 434 German Civil Code (BGB)) of third parties;

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                                                       Contribution Agreement 10

        (b)   the assets transferred in this Agreement constitute all the
              material assets, properties, intellectual property and other
              rights of Aventis that are necessary for the conduct of the J.V.
              Business as at the Contribution Date conducted by Aventis;

        (c)   the assets transferred in this Agreement and presently used are in
              good condition and repair, reasonable tear and wear excepted;

        (d)   to the best knowledge of Aventis, the Contracts are in full force
              and effective and valid and enforceable in accordance with their
              respective terms against Aventis and, to Aventis' knowledge, the
              other party thereto;

        (e)   to the best knowledge of Aventis, no proceedings have been
              instituted, are pending or are threatened, which challenge
              Aventis' rights in respect of the patents listed in EXHIBITS 3 and
              4 or the IPR listed in EXHIBIT 5.

        (f)   other than the employees listed in EXHIBIT 7 and the managing
              director Mr. Norbert Windhab no other employees shall be
              transferred to the J.V. pursuant to this Agreement

(2)     Unless otherwise provided for herein, Aventis does not give any
        warranties.

B.      CONTRIBUTION BY NANOGEN


SECTION 9      CONTRIBUTION BY NANOGEN

(1)     Pursuant to the provisions set forth below, Nanogen hereby assigns and
        transfers to the J.V. effective as of the Contribution Date

        a)     Nanogen' ownership interest in any and all patents, patent
               disclosures, patent applications, including all provisionals,
               continuations (in whole or in part), divisionals, reissues,
               extensions, supplementary protection certificates, reexaminations
               and foreign counterparts thereof, as well as all jointly owned
               inventions by Aventis and Nanogen, as listed in EXHIBIT 4.

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                                                       Contribution Agreement 11

        b)    Nanogen's ownership interest in IPR jointly owned by Aventis and
              Nanogen, to the extent possible listed in EXHIBIT 12.

              Nanogen shall make available to the J.V. without undue delay after
              the Contribution Date all records, documents, files, results,
              plans and other materials relating exclusively to know-how
              contributed to the J.V. as provided for in this Agreement which
              the J.V. requires to understand, assess and exploit such know-how.

        Except for the effect, if any, of the proceedings presently pending in
        the matter entitled "NANOGEN ET AL. VS. MOTOROLA ET AL.", case number
        "Civil No. 00cv0872 lEG (AJB)" in the Federal District Court of the
        Southern District of California, Nanogen warrants that to the best
        knowledge of Nanogen, no proceedings have been instituted, are pending
        or are threatened, which challenge Nanogen's rights in respect of the
        patents listed in EXHIBIT 4 or the IPR listed in EXHIBIT 12.

(2)     Unless otherwise provided for herein, Nanogen does not give any
        warranties

C.      GENERAL

SECTION 10     NOTICES

(1)     All notices or other communications hereunder shall be in writing,
        unless a stricter form should be required by applicable law.

(2)     All notices or communications shall be sent to the following addresses,
        or to such other addresses of which a party may have informed the other
        party from time to time, which change of address shall be effective only
        when received by the other parties:

        a)    If to Aventis:
              Aventis Research & Technologies GmbH & Co KG
              Industriepark Hochst, Building G 865 A
              65926 Frankfurt am Main
              Germany

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                                                       Contribution Agreement 12

              Attention: Geschaftsleitung

        b)    If to the J.V.:
              Nanogen Recognomics GmbH
              Industriepark Hochst, Building G 830
              65926 Frankfurt am Main
              Germany
              Attention:  Geschaftsleitung

        c)    If to Nanogen:
              Nanogen Inc.
              10398 Pacific Center Court
              San Diego, Ca 92121
              USA
              Attention:  Management

SECTION 11     SEVERABILITY

(1)     Should any provision of this Agreement be or become invalid,
        ineffective, or unenforceable, the remaining provisions of this
        Agreement shall be valid.

(2)     The parties agree to replace the invalid, ineffective, or unenforceable
        provision by a valid, effective, and enforceable provision which
        economically best meets the intention of the parties had they foreseen
        the invalidity, ineffectiveness, or unenforceability at that time. The
        same shall apply in the case of an omission or if the Agreement is
        silent.

(3)     If a provision of this Agreement should be held invalid by a competent
        court or arbitration tribunal because of the scope of its coverage (such
        as territory, subject matter, time period or amount), said provision
        shall not be deemed to be completely invalid but shall be deemed to be
        valid with the permissible scope that is nearest to the originally
        agreed-upon scope.

SECTION 12     Entire Agreement Contribution Agreement

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                                                       Contribution Agreement 13

(1)     This Agreement including all Exhibits thereto contain the entire
        agreement and understanding of the parties thereto in respect of the
        transaction contemplated by this Agreement. This Agreement supersedes
        all other prior agreements and understandings, both written and oral,
        among the parties or among and between any of them with respect to such
        transactions, provided, however, that such prior agreements and
        understanding may to the extent necessary and appropriate be used for
        the interpretation of this Agreement.

(2)     There are no restrictions, promises, representations, warranties,
        covenants or undertakings, other than those expressly set forth or
        referred to herein.

(3)     Any changes of this Agreement have to be made in writing.

(4)     This Agreement has been made and is binding in the English language.

SECTION 13     APPLICABLE LAW AND VENUE

This Agreement shall be governed by and construed in accordance with the laws of
the Federal Republic of Germany.

SECTION 14     ARBITRATION

(1)     All disputes arising in connection with or out of this Agreement shall
        be finally settled under the Rules of Conciliation and Arbitration of
        the International Chamber of Commerce by three arbitrators appointed in
        accordance with the said Rules.

(2)     Such arbitration shall take place in Frankfurt am Main, Germany, and
        shall be held in the English language. The arbitrators shall apply the
        laws of the Federal Republic of Germany.

SECTION 15     CONDITION PRECEDENT

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                                                       Contribution Agreement 14

The contribution of the J.V. Business from Aventis to the J.V. as provided for
in this Agreement is conditioned on Aventis Research & Technologies GmbH & Co.
KG, Frankfurt am Main, Germany, Nanogen Inc., San Diego, USA and Nanogen
Recognomics GmbH, Frankfurt am Main, Germany executing the Cooperation and
Shareholders' Agreement dated _____________.

Frankfurt, June 27, 2001                /s/ Jan C. Kobbach
                                        ------------------------------------
                                        Aventis Research & Technologies GmbH &
                                        CoKG
                                        Represented by Aventis Research &
                                        Technologies Verwaltungs GmbH
                                        by: Jan Christoph Kobbach pursuant to
                                        a power of
                                        attorney dated June ____, 2001.

Frankfurt, June 27, 2001                /s/ Jan C. Kobbach
                                        ------------------------------------
                                        Nanogen Recognomics GmbH
                                        by: Jan Christoph Kobbach pursuant to a
                                        power of attorney dated June ____, 2001.

Frankfurt, June 27, 2001                /s/ Jorg Siegels
                                        ------------------------------------
                                        Nanogen Inc.
                                        by: Dr. Jorg Siegels pursuant to a power
                                        of attorney dated June 18, 2001.

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                                                     Exhibit 1, Section 1 (1) a)
                                                   to the Contribution Agreement
                          Nanogen / Aventis Research Technologies GmbH & Co. KG.

(XXX)

(XXX) - Confidential material redacted and filed separately with the
        Commission

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                                                     Exhibit 2, Section 1 (1) c)
                                                   to the Contribution Agreement
                          Nanogen / Aventis Research Technologies GmbH & Co. KG.

(XXX)

(XXX) - Confidential material redacted and filed separately with the
        Commission

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(XXX)

(XXX) - Confidential Information redacted and filed separately with the
        Commission

<Page>

(XXX)

(XXX) - Confidential Information redacted and filed separately with the
        Commission

<Page>

(XXX)

(XXX) - Confidential Information redacted and filed separately with the
        Commission

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                                                     Exhibit 5, Section 1 (1) f)
                                                   to the Contribution Agreement
                          Nanogen / Aventis Research Technologies GmbH & Co. KG.

(XXX)

(XXX) - Confidential Information redacted and filed separately with the
        Commission

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                                                     Exhibit 6, Section 1 (1) e)
                                                   to the Contribution Agreement
                          Nanogen / Aventis Research Technologies GmbH & Co. KG.

(XXX)

(XXX) - Confidential Information redacted and filed separately with the
        Commission

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                                                     Exhibit 6, Section 1 (1) g)
                                                   to the Contribution Agreement
                          Nanogen / Aventis Research Technologies GmbH & Co. KG.

(XXX)

(XXX) - Confidential Information redacted and filed separately with the
        Commission

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                                                        Exhibit 7, Section 3 (1)
                                                   to the Contribution Agreement
                          Nanogen / Aventis Research Technologies GmbH & Co. KG.


Nanogen Recognomics GmbH         Employee List

(XXX)

(XXX) - Confidential Information redacted and filed separately with the
        Commission