Document:

Exhibit 4.2 

SECURITY AGREEMENT  

        THIS
SECURITY AGREEMENT dated as of November 20, 2003 (“Security
Agreement”), is made by and among PFC Therapeutics, LLC, a Delaware
limited liability company (“Grantor”), and Technology
Gateway Partnership, L.P., a California limited partnership (“Secured
Party”). 

RECITALS 

         A.       
          The Secured Party has made an advance of money to Grantor as evidenced by that
          certain Secured Convertible Note executed by Grantor in favor of the Secured
          Party (the “Note”), such advance being referred
          to herein as the “Loan”. 

         B.       
          The Secured Party is willing to make the Loan to Grantor, but only upon the
          condition, among others, that Grantor shall have executed and delivered to the
          Secured Party this Security Agreement. 

AGREEMENT 

        NOW,
THEREFORE, in order to induce the Secured Party to make the Loan and for other good
and valuable consideration, the receipt and adequacy of which are hereby acknowledged, and
intending to be legally bound, Grantor hereby represents, warrants, covenants and agrees
as follows: 

    1.           DEFINED
TERMS. When used in this Security Agreement the following terms           shall have
the following meanings (such meanings being equally applicable to           both the
singular and plural forms of the terms defined):  

        “Bankruptcy
Code” means Title XI of the United States Code. 

        “Collateral”
shall have the meaning assigned to such term in Section 2 of this Security
Agreement. 

        “Contracts”
means all contracts (including any customer, vendor, supplier, service or maintenance
contract), leases, licenses, undertakings, purchase orders, permits, franchise agreements
or other agreements (other than any right evidenced by Chattel Paper, Documents or
Instruments), whether in written or electronic form, in or under which Grantor now holds
or hereafter acquires any right, title or interest, including, without limitation, with
respect to an Account, any agreement relating to the terms of payment or the terms of
performance thereof. 

        “Copyright
License” means any agreement, whether in written or electronic form,
in which Grantor now holds or hereafter acquires any interest, granting any right in or to
any Copyright or Copyright registration (whether Grantor is the licensee or the licensor
thereunder) including, without limitation, licenses pursuant to which Grantor has obtained
the exclusive right to use a copyright owned by a third party. 

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        “Copyrights”
means all of the following now owned or hereafter acquired or created (as a work for hire
for the benefit of Grantor) by Grantor or in which Grantor now holds or hereafter acquires
or receives any right or interest, in whole or in part: (a) all copyrights, whether
registered or unregistered, held pursuant to the laws of the United States, any State
thereof or any other country; (b) registrations, applications, recordings and proceedings
in the United States Copyright Office or in any similar office or agency of the United
States, any State thereof or any other country; (c) any continuations, renewals or
extensions thereof; (d) any registrations to be issued in any pending applications, and
shall include any right or interest in and to work protectable by any of the foregoing
which are presently or in the future owned, created or authorized (as a work for hire for
the benefit of Grantor) or acquired by Grantor, in whole or in part; (e) prior versions of
works covered by copyright and all works based upon, derived from or incorporating such
works; (f) income, royalties, damages, claims and payments now and hereafter due and/or
payable with respect to copyrights, including, without limitation, damages, claims and
recoveries for past, present or future infringement; (g) rights to sue for past, present
and future infringements of any copyright; and (h) any other rights corresponding to any
of the foregoing rights throughout the world. 

        “Event
of Default” means (i) any failure by Grantor forthwith to pay or
perform any of the Secured Obligations and, (ii) any breach by Grantor of any warranty,
representation, or covenant set forth herein. 

        “Intellectual
Property” means any intellectual property, in any medium, of any kind
or nature whatsoever, now or hereafter owned or acquired or received by Grantor or in
which Grantor now holds or hereafter acquires or receives any right or interest, and shall
include, in any event, any Copyright, Trademark, Patent, trade secret, customer list,
internet domain name (including any right related to the registration thereof),
proprietary or confidential information, mask work, source, object or other programming
code, invention (whether or not patented or patentable), technical information, procedure,
design, knowledge, know-how, software, data base, data, skill, expertise, recipe,
experience, process, model, drawing, material or record. 

        “License”
means any Copyright License, Patent License, Trademark License or other license of rights
or interests, whether in-bound or out-bound, whether in written or electronic form, now or
hereafter owned or acquired or received by Grantor or in which Grantor now holds or
hereafter acquires or receives any right or interest, and shall include any renewals or
extensions of any of the foregoing thereof. 

        “Lien”
means any mortgage, lien, deed of trust, charge, pledge, security interest or other
encumbrance. 

        “Patent
License” means any agreement, whether in written or electronic form,
in which Grantor now holds or hereafter acquires any interest, granting any right with
respect to any invention on which a Patent is in existence (whether Grantor is the
licensee or the licensor thereunder). 

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        “Patents”
means all of the following in which Grantor now holds or hereafter acquires any interest:
(a) all letters patent of the United States or any other country, all registrations and
recordings thereof and all applications for letters patent of the United States or any
other country, including, without limitation, registrations, recordings and applications
in the United States Patent and Trademark Office or in any similar office or agency of the
United States, any State thereof or any other country; (b) all reissues, divisions,
continuations, renewals, continuations-in-part or extensions thereof; (c) all petty
patents, divisionals and patents of addition; (d) all patents to issue in any such
applications; (e) income, royalties, damages, claims and payments now and hereafter due
and/or payable with respect to patents, including, without limitation, damages, claims and
recoveries for past, present or future infringement; and (f) rights to sue for past,
present and future infringements of any patent. 

        “Secured
Obligations” means (a) the obligation of Alliance Pharmaceutical Corp.
(“Alliance”) to pay the Secured Party all amounts due under
the Note and the Guaranty and Security Agreement executed by Alliance in favor of Secured
Party (as the same may be amended, modified, supplemented or restated from time to time),
and (b) the obligation of Grantor to pay any fees, costs and expenses of the Secured Party
under Section 6(c) hereof. 

        “Security
Agreement” means this Security Agreement and all Schedules hereto, as
the same may from time to time be amended, modified, supplemented or restated. 

        “Trademark
License” means any agreement, whether in written or electronic form,
in which Grantor now holds or hereafter acquires any interest, granting any right in and
to any Trademark or Trademark registration (whether Grantor is the licensee or the
licensor thereunder). 

        “Trademarks”
means any of the following in which Grantor now holds or hereafter acquires any interest:
(a) any trademarks, tradenames, corporate names, company names, business names, trade
styles, service marks, logos, other source or business identifiers, prints and labels on
which any of the foregoing have appeared or appear, designs and general intangibles of
like nature, now existing or hereafter adopted or acquired, all registrations and
recordings thereof and any applications in connection therewith, including, without
limitation, registrations, recordings and applications in the United States Patent and
Trademark Office or in any similar office or agency of the United States, any State
thereof or any other country (collectively, the “Marks”); (b) any reissues,
extensions or renewals thereof; (c) the goodwill of the business symbolized by or
associated with the Marks; (d) income, royalties, damages, claims and payments now and
hereafter due and/or payable with respect to the Marks, including, without limitation,
damages, claims and recoveries for past, present or future infringement; and (e) rights to
sue for past, present and future infringements of the Marks. 

        “UCC”
means the Uniform Commercial Code as the same may from time to time be in effect in the
State of California (and each reference in this Security Agreement to an
Article thereof (denoted as a Division of the UCC as adopted and in effect in the
State of California) shall refer to that Article (or Division, as applicable) as from
time to time in effect, which in the case of Article 9 shall include and refer to
Revised Article 9 from and after the date Revised Article 9 shall become
effective in the State of California); provided, however, in the event that, by
reason of mandatory provisions of law, any or all of the attachment, perfection or
priority of the Secured Party’s security interest in any Collateral is governed by
the Uniform Commercial Code as in effect in a jurisdiction other than the State of
California, the term “UCC” shall mean the Uniform Commercial Code
(including the Articles thereof) as in effect at such time in such other jurisdiction for
purposes of the provisions hereof relating to such attachment, perfection or priority and
for purposes of definitions related to such provisions. 

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        In
addition, the following terms shall be defined terms having the meaning set forth for such
terms in the UCC: “Account” (including health-care-insurance receivables),
“Account Debtor”, “Chattel Paper” (including tangible and electronic
chattel paper), “Commercial Tort Claims”, “Commodity Account”,
“Deposit Account”, “Documents”, “Equipment” (including all
accessions and additions thereto), “Fixtures”, “General Intangible”
(including payment intangibles and software), “Instrument”,
“Inventory” (including all goods held for sale or lease or to be furnished under
a contract of service, and including returns and repossessions), “Investment
Property” (including securities and securities entitlements), “Letter-of-Credit
Right” (whether or not the letter of credit is evidenced by a writing), “Payment
Intangibles”, “Proceeds”, “Promissory Notes”, “Securities
Account”, and “Supporting Obligations”. Each of the foregoing defined terms
shall include all of such items now owned, or hereafter acquired, by Grantor. 

    2.           GRANT
OF SECURITY INTEREST. As collateral security for the full, prompt,           complete
and final payment and performance when due (whether at stated maturity,           by
acceleration or otherwise) of all the Secured Obligations and in order to
          induce the Secured Party to cause the Loans to be made, Grantor hereby assigns,
          conveys, mortgages, pledges, hypothecates and transfers to the Secured Party, a
          security interest in all of Grantor’s right, title and interest in, to and
          under the following, whether now owned or hereafter acquired, (all of which
          being collectively referred to herein as the           “Collateral”):  

            (a)                     All
Accounts of Grantor;  

            (b)                     All
Chattel Paper of Grantor;  

            (c)                     All
Commercial Tort Claims of Grantor;  

            (d)                     All
Contracts of Grantor;  

            (e)                     All
Deposit Accounts of Grantor;  

            (f)                     All
Documents of Grantor;  

            (g)                     All
Equipment of Grantor;  

            (h)                     All
Fixtures of Grantor;  

            (i)                     All
General Intangibles of Grantor, including, without limitation,           Payment
Intangibles, all Copyrights, Patents, Trademarks, Licenses, designs,           drawings,
technical information, marketing plans, customer lists, trade secrets,
          proprietary or confidential information, inventions (whether or not
patentable),           procedures, know-how, models and data; 

            (j)                     All
Instruments of Grantor, including, without limitation, Promissory Notes;  

            (k)                     All
Inventory of Grantor;  

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            (l)                     All
Investment Property of Grantor;  

            (m)                     All
Letter-of Credit Rights of Grantor;  

            (n)                     All
Supporting Obligations of Grantor;  

            (o)                     All
property of Grantor held by the Secured Party, or any other party for whom           the
Secured Party is acting as agent hereunder, including, without limitation,           all
property of every-description now or hereafter in the possession or custody           of
or in transit to the Secured Party or such other party for any purpose,
          including, without limitation, safekeeping, collection or pledge, for the
          account of Grantor, or as to which Grantor may have any right or power;  

            (p)                     All
other goods and personal property of Grantor, wherever located, whether
          tangible or intangible, and whether now owned or hereafter acquired, existing,
          leased or consigned by or to Grantor; and  

            (q)                     To
the extent not otherwise included, all Proceeds of each of the foregoing and
          all accessions to, substitutions and replacements for and rents, profits and
          products of each of the foregoing.  

        Notwithstanding
the foregoing provisions of this Section 2, the grant, assignment and transfer of a
security interest as provided herein shall not extend to, and the term
“Collateral” shall not include any Contract, Instrument or Chattel Paper
in which Grantor has any right, title or interest if and to the extent such Contract,
Instrument or Chattel Paper includes a provision containing a restriction on assignment
such that the creation of a security interest in the right, title or interest of Grantor
therein would be prohibited and would, in and of itself, cause or result in a default
thereunder enabling another person party to such Contract, Instrument or Chattel Paper to
enforce any remedy with respect thereto; provided that the foregoing exclusion
shall not apply if (i) such prohibition has been waived or such other person has otherwise
consented to the creation hereunder of a security interest in such Contract, Instrument or
Chattel Paper or (ii) such prohibition would be rendered ineffective pursuant to
Sections 9-407(a) or 9-408(a) of the UCC, as applicable and as then in effect in any
relevant jurisdiction, or any other applicable law (including the Bankruptcy Code) or
principles of equity); provided further that immediately upon the ineffectiveness,
lapse or termination of any such provision, the Collateral shall include, and Grantor
shall be deemed to have granted a security interest in, all its rights, title and
interests in and to such Contract, Instrument or Chattel Paper as if such provision had
never been in effect; and provided further that the foregoing exclusion shall in no
way be construed so as to limit, impair or otherwise affect the Secured Party’s
unconditional continuing security interest in and to all rights, title and interests of
Grantor in or to any payment obligations or other rights to receive monies due or to
become due under any such Contract, Instrument or Chattel Paper and in any such monies and
other proceeds of such Contract, Instrument or Chattel Paper. 

    3.           RIGHTS
OF SECURED PARTY; COLLECTION OF ACCOUNTS. 

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            (a)                     Notwithstanding
anything contained in this Security Agreement to the contrary,           Grantor
expressly agrees that it shall remain liable under each of its Contracts           and
each of its Licenses to observe and perform all the conditions and           obligations
to be observed and performed by it thereunder and that it shall           perform all of
its duties and obligations thereunder, all in accordance with and           pursuant to
the terms and provisions of each such Contract or License. The           Secured Party
shall not have any obligation or liability under any Contract or           License by
reason of or arising out of this Security Agreement or the granting           to the
Secured Party of a lien therein or the receipt by the Secured Party of           any
payment relating to any Contract or License pursuant hereto, nor shall the
          Secured Party be required or obligated in any manner to perform or fulfill any
          of the obligations of Grantor under or pursuant to any Contract or License, or
          to make any payment, or to make any inquiry as to the nature or the sufficiency
          of any payment received by it or the sufficiency of any performance by any
party           under any Contract or License, or to present or file any claim, or to
take any           action to collect or enforce any performance or the payment of any
amounts which           may have been assigned to it or to which it may be entitled at
any time or           times.  

            (b)                     The
Secured Party authorizes Grantor to collect its Accounts. Upon the           occurrence
and during the continuance of any Event of Default, at the request of           the
Secured Party, Grantor shall deliver all original and other documents
          evidencing and relating to the performance of labor or service which created
          such Accounts, including, without limitation, all original orders, invoices and
          shipping receipts.  

            (c)                     The
Secured Party may at any time, upon the occurrence and during the           continuance
of any Event of Default, notify Account Debtors of Grantor, parties           to the
Contracts of Grantor, obligors in respect of Instruments of Grantor and
          obligors in respect of Chattel Paper of Grantor that the Accounts and the
right,           title and interest of Grantor in and under such Contracts, Instruments
and           Chattel Paper have been assigned to the Secured Party and that payments
shall be           made directly to the Secured Party. Upon the request of the Secured
Party,           Grantor shall so notify such Account Debtors, parties to such Contracts,
          obligors in respect of such Instruments and obligors in respect of such Chattel
          Paper. Upon the occurrence and during the continuance of any Event of Default,
          the Secured Party may communicate with such Account Debtors, parties to such
          Contracts, obligors in respect of such Instruments and obligors in respect of
          such Chattel Paper to verify with such parties, to the Secured Party’s
          satisfaction, the existence, amount and terms of any such Accounts, Contracts,
          Instruments or Chattel Paper.  

    4.           REPRESENTATIONS
AND WARRANTIES. Grantor hereby represents and warrants to           the Secured Party
that:  

            (a)                     Except
for the security interest granted to the Secured Party under this           Security
Agreement, Grantor is the sole legal and equitable owner of each item           of the
Collateral in which it purports to grant a security interest hereunder.  

            (b)                     No
effective security agreement, financing statement, equivalent security or           lien
instrument or continuation statement covering all or any part of the           Collateral
exists, except (i) any security agreement, financing statement,           equivalent
security or lien instrument or continuation statement as may have           been filed by
Grantor in favor of the Secured Party pursuant to this Security           Agreement, and
(ii) the Percentage Fee Agreement (the “Percentage Fee           Agreement”)
dated June 18, 2003 by and between Grantor,           Alliance Pharmaceutical Corp. (“Alliance”)
and           Baxter Healthcare Corporation (“Baxter”),
and any           financing statement, equivalent security or lien instrument or
continuation           statement filed pursuant to the Percentage Fee Agreement (the “Related
Filings”); provided, however, that           Baxter’s rights
under the Percentage Fee Agreement and the Related Filings           with respect to the
Collateral shall, pursuant to the terms of the Percentage           Fee Agreement, be
subordinate to Secured Party’s rights under this Security           Agreement.  

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            (c)                     This
Security Agreement creates a legal and valid security interest on and in           all of
the Collateral in which Grantor now has rights.  

            (d)                     Grantor’s
taxpayer identification number is, and chief executive office,           principal place
of business, and the place where Grantor maintains its records           concerning the
Collateral are presently located at the address set forth on the           signature page
hereof. The Collateral, other than Deposit Accounts, Securities           Accounts,
Commodity Accounts and motor vehicles and other mobile goods of the           type
contemplated in Section 9103(3)(a) of the UCC, is presently located at such
          address and at such additional addresses set forth on Schedule A attached
          hereto.  

            (e)                     All
Collateral of Grantor consisting of Chattel Paper, Instruments or Investment
          Property is set forth on Schedule B attached hereto.  

            (f)                     The
name and address of each depository institution at which Grantor maintains           any
Deposit Account and the account number and account name of each such Deposit
          Account is listed on Schedule C attached hereto. The name and address of
          each securities intermediary or commodity intermediary at which Grantor
          maintains any Securities Account or Commodity Account and the account number
and           account name is listed on Schedule C attached hereto. Grantor agrees
to           amend Schedule C upon the Secured Party’s request to reflect the
          opening of any additional Deposit Account, Securities Account or Commodity
          Account, or closing or changing the account name or number on any existing
          Deposit Account, Securities Account, or Commodity Account.  

            (g)                     All
Copyrights, Copyright Licenses, Patents, Patent Licenses, Trademarks and
          Trademark Licenses now owned or held by Grantor are listed on Schedule D          attached
hereto.  

    5.           COVENANTS.
Unless the Secured Party otherwise consents (which consent           shall not be
unreasonably withheld), Grantor covenants and agrees with the           Secured Party
that from and after the date of this Security Agreement and until           the Secured
Obligations have been performed and paid in full:  

            (a)                     Grantor
shall not sell, lease, transfer or otherwise dispose of any of the           Collateral
(each, a “Transfer”), or attempt or contract to do so,           other than (a)
the sale of Inventory in the ordinary course of business, (b) the           granting of
Licenses in the ordinary course of business and (c) the disposal of           worn-out or
obsolete Equipment.  

            (b)                     Grantor
shall not change its jurisdiction of organization or relocate its chief
          executive office, principal place of business or its records from such
          address(es) provided to the Secured Party pursuant to Section 4(d)          above
without at least seven (7) days prior notice to the Secured Party.  

            (c)                     Grantor
shall not, directly or indirectly, create, permit or suffer to exist,           and shall
defend the Collateral against and take such other action as is           necessary to
remove, any Lien on the Collateral, except (i) the Lien granted to           the Secured
Party under this Security Agreement and (ii) the Lien granted to           Baxter
pursuant to the Percentage Fee Agreement, which Lien shall, pursuant to           the
terms of the Percentage Fee Agreement, be subordinate to the Lien granted to
          the Secured Party under this Security Agreement.  

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            (d)                     Grantor
shall maintain insurance policies insuring the Collateral against loss           or
damage from such risks and in such amounts and forms and with such companies           as
are customarily maintained by businesses similar to Grantor.  

            (e)                     Grantor
shall pay promptly when due all property and other taxes, assessments           and
government charges or levies imposed upon, and all claims (including claims           for
labor, materials and supplies) against, the Equipment, Fixtures or           Inventory,
except to the extent the validity or amount thereof is being           contested in good
faith and adequate reserves are being maintained in connection           therewith.  

            (f)                     Grantor
shall use commercially reasonable efforts to (i) protect, defend and           maintain
the validity and enforceability of all Copyrights, Patents and           Trademarks
material to Grantor’s business and (ii) detect infringements of           all
Copyrights, Patents and Trademarks material to Grantor’s business.  

            (g)                     At
any time and from time to time, upon the written request of the Secured           Party,
and at the sole expense of Grantor, Grantor shall promptly and duly           execute and
deliver any and all such further instruments and documents and take           such
further action as the Secured Party may reasonably deem necessary or           desirable
to obtain the full benefits of this Security Agreement, including,           without
limitation, (a) executing, delivering and causing to be filed any
          financing or continuation statements (including “in lieu” continuation
          statements) under the UCC with respect to the security interests granted
hereby,           (b) at the Secured Party’ reasonable request, filing or
cooperating with           the Secured Party in filing any forms or other documents
required to be recorded           with the United States Patent and Trademark Office,
United States Copyright           Office, (c) at the Secured Party’s reasonable
request, placing the           interest of the Secured Party as lienholder on the
certificate of title (or           similar evidence of ownership) of any vehicle,
watercraft or other Equipment           constituting Collateral owned by Grantor which is
covered by a certificate of           title (or similar evidence of ownership), (d) executing
and delivering and           using commercially reasonable efforts to cause the
applicable depository           institution, securities intermediary, commodity
intermediary or issuer or           nominated party under a letter of credit to execute
and deliver a collateral           control agreement with respect to any Deposit Account,
Securities Account or           Commodity Account or Letter-of-Credit Right in or to
which Grantor has any right           or interest and (e) at the Secured Party’s
reasonable request, using           commercially reasonable efforts to obtain
acknowledgments from bailees having           possession of any Collateral and waivers of
liens from landlords and mortgagees           of any location where any of the Collateral
may from time to time be stored or           located. Grantor also hereby authorizes the
Secured Party to file any such           financing or continuation statement (including
“in lieu” continuation           statements) without the signature of Grantor.  

    6.           RIGHTS
AND REMEDIES UPON DEFAULT. Beginning on the date which is ten           (10)business
daysafter any Event of Default shall have occurred           and while such Event
of Default is continuing:  

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            (a)                     The
Secured Party may exercise in addition to all other rights and remedies           granted
to the Secured Party under this Security Agreement, all rights and           remedies of
a secured party under the UCC. Without limiting the generality of           the
foregoing, Grantor expressly agrees that in any such event the Secured           Party,
without demand of performance or other demand, advertisement or notice of           any
kind (except the notice specified below of time and place of public or           private
sale) to or upon Grantor or any other person, may (i) reclaim, take           possession,
recover, store, maintain, finish, repair, prepare for sale or lease,           shop,
advertise for sale or lease and sell or lease (in the manner provided           herein)
the Collateral, and in connection with the liquidation of the Collateral           and
collection of the accounts receivable pledged as Collateral, use any           Trademark,
Copyright, or process used or owned by Grantor and (ii) forthwith           collect,
receive, appropriate and realize upon the Collateral, or any part           thereof, and
may forthwith sell, lease, assign, give an option or options to           purchase or
sell or otherwise dispose of and deliver said Collateral (or           contract to do
so), or any part thereof, in one or more parcels at public or           private sale or
sales, at any exchange or broker’s board or at the Secured           Party’s
offices or elsewhere at such prices as it may deem commercially           reasonable, for
cash or on credit or for future delivery without assumption of           any credit risk.
Grantor further agrees, at the Secured Party’s request, to           assemble its
Collateral and make it available to the Secured Party at places           which the
Secured Party shall reasonably select, whether at Grantor’s           premises or
elsewhere. The Secured Party shall apply the net proceeds of any           such
collection, recovery, receipt, appropriation, realization or sale as           provided
in Section 6(e), below, with Grantor remaining liable for           any
deficiency remaining unpaid after such application. Grantor agrees that the
          Secured Party need not give more than twenty (20) days’ notice of the time
          and place of any public sale or of the time after which a private sale may take
          place and that such notice is reasonable notification of such matters.  

            (b)                     As
to any Collateral constituting certificated securities or uncertificated
          securities, if, at any time when the Secured Party shall determine to exercise
          their right to sell the whole or any part of such Collateral hereunder, such
          Collateral or the part thereof to be sold shall not, for any reason whatsoever,
          be effectively registered under Securities Act of 1933, as amended (as so
          amended the “Act”), the Secured Party may, in
          their discretion (subject only to applicable requirements of law), sell such
          Collateral or part thereof by private sale in such manner and under such
          circumstances as the Secured Party may deem necessary or advisable, but subject
          to the other requirements of this Section 6(b), and shall not be
          required to effect such registration or cause the same to be effected. Without
          limiting the generality of the foregoing, in any such event the Secured Party
          may, in their discretion, (i) in accordance with applicable securities
          laws, proceed to make such private sale notwithstanding that a registration
          statement for the purpose of registering such Collateral or part thereof could
          be or shall have been filed under the Act; (ii) approach and negotiate
with           a single possible purchaser to effect such sale; and (iii) restrict
          such sale to a purchaser who will represent and agree that such purchaser
          is purchasing for its own account, for investment, and not with a view to
          the distribution or sale of such Collateral or part thereof. In addition to
          a private sale as provided above in this Section 6(b), if any
          of such Collateral shall not be freely distributable to the public without
          registration under the Act at the time of any proposed sale hereunder, then the
          Secured Party shall not be required to effect such registration or cause the
          same to be effected but may, in their discretion (subject only to applicable
          requirements of law), require that any sale hereunder (including a sale at
          auction) be conducted subject to such restrictions as the Secured Party may, in
          their discretion, deem necessary or appropriate in order that such sale
          (notwithstanding any failure so to register) may be effected in compliance with
          the Bankruptcy Code and other laws affecting the enforcement of creditors’          rights
and the Act and all applicable state securities laws.  

9 

            (c)                     Grantor
also agrees to pay all fees, costs and expenses of the Secured Party,
          including, without limitation, reasonable attorneys’ fees, incurred in
          connection with the enforcement of any of its rights and remedies hereunder.  

            (d)                     Grantor
hereby waives presentment, demand, protest or any notice (to the maximum           extent
permitted by applicable law) of any kind in connection with this Security
          Agreement or any Collateral.  

            (e)                     The
Proceeds of any sale, disposition or other realization upon all or any part           of
the Collateral shall be distributed by the Secured Party in the following           order
of priorities:  

            FIRST,
to the Secured Party in an amount sufficient to pay in full the reasonable costs of the
Secured Party in connection with such sale, disposition or other realization, including
all fees, costs, expenses, liabilities and advances incurred or made by the Secured Party
in connection therewith, including, without limitation, reasonable attorneys’ fees; 

            SECOND,
to the Secured Party in an amount equal to the then unpaid Secured Obligations of the
Secured Party; and 

            FINALLY,
upon payment in full of the Secured Obligations, to Grantor or its representatives, in
accordance with the UCC or as a court of competent jurisdiction may direct. 

    7.           INDEMNITY.
Grantor agrees to defend, indemnify and hold harmless the           Secured Party and
their officers, employees, and agents against (a) all           obligations, demands,
claims, and liabilities claimed or asserted by any other           party in connection
with the transactions contemplated by this Security           Agreement and (b) all
losses or expenses in any way suffered, incurred, or paid           by the Secured Party
as a result of or in any way arising out of, following or           consequential to
transactions between or among the Secured Party and Grantor,           whether under this
Security Agreement or otherwise (including without           limitation, reasonable
attorneys fees and expenses), except for losses arising           from or out of the
gross negligence or willful misconduct of the Secured Party,           as applicable.  

    8.           REINSTATEMENT.
This Security Agreement shall remain in full force and           effect and continue to
be effective should any petition be filed by or against           Grantor for liquidation
or reorganization, should Grantor become insolvent or           make an assignment for
the benefit of creditors or should a receiver or trustee           be appointed for all
or any significant part of Grantor’s property and           assets, and shall
continue to be effective or be reinstated, as the case may be,           if at any time
payment and performance of the Secured Obligations, or any part           thereof, is,
pursuant to applicable law, rescinded or reduced in amount, or must           otherwise
be restored or returned by any obligee of the Secured Obligations,           whether as a
“voidable preference,” “fraudulent conveyance,”          or
otherwise, all as though such payment or performance had not been made. In           the
event that any payment, or any part thereof, is rescinded, reduced, restored           or
returned, the Secured Obligations shall be reinstated and deemed reduced only
          by such amount paid and not so rescinded, reduced, restored or returned.  

10 

    9.           MISCELLANEOUS. 

            (a)                     Any
amendment of this Security Agreement shall require the written consent of           the
Grantor and the Secured Party.  

            (b)                     Subject
to Section 8 hereof, this Security Agreement shall terminate           upon
the closing of a Financing (as defined below). For purposes of this           Agreement,
the term “Financing” means a financing pursuant to which           the Company
receives gross proceeds of $10,000,000 (or such other amount           approved by the
Secured Party (which approval shall not be unreasonably           withheld) from one or
more investors, strategic partners, or other sources (or           any combination of the
foregoing). By way of example, the equity financing           contemplated by the Term
Sheet dated November 7, 2003 by and among Alliance and           SRS Capital-West, Inc.
(as the same may be amended, modified, supplemented or           restated from time to
time) would be a Financing under this Security Agreement.  

            (c)                     This
Security Agreement and all obligations of Grantor hereunder shall be           binding
upon the successors and assigns of Grantor, and shall, together with the           rights
and remedies of the Secured Party hereunder, inure to the benefit of the
          Secured Party, any future holder of any of the indebtedness and their
respective           successors and assigns. No sales of participations, other sales,
assignments,           transfers or other dispositions of any agreement governing or
instrument           evidencing the Secured Obligations or any portion thereof or
interest therein           shall in any manner affect the lien granted to the Secured
Party hereunder.  

            (d)                     In
all respects, including all matters of construction, validity and           performance,
this Security Agreement and the Secured Obligations arising           hereunder shall be
governed by, and construed and enforced in accordance with,           the laws of the
State of California applicable to contracts made and performed           in such state,
without regard to the principles thereof regarding conflict of           laws, except to
the extent that the UCC provides for the application of the law           of Grantor’s
State.  

            (e)                     This
Agreement may be executed in any number of counterparts, each of which           shall be
an original, but all of which together shall constitute one instrument.  

            (f)                     Any
and all notices required or permitted to be given to a party pursuant to the
          provisions of this Agreement will be in writing and will be effective and
deemed           to provide such party sufficient notice under this Agreement on the
earliest of           the following: (i) at the time of personal delivery, if
delivery is in           person; (ii) at the time of transmission by facsimile, addressed
to the other           party at its facsimile number specified herein (or hereafter
modified by           subsequent notice to the parties hereto), with confirmation of
receipt made by           both telephone and printed confirmation sheet verifying
successful transmission           of the facsimile; (iii) one (1) business day after
deposit with an express           overnight courier for United States deliveries, or two
(2) business days after           such deposit for deliveries outside of the United
States, with proof of delivery           from the courier requested; or (iv) three (3)
business days after deposit in the           United States mail by certified mail (return
receipt requested) for United           States deliveries. All notices for delivery
outside the United States will be           sent by facsimile or by express courier. All
notices not delivered personally or           by facsimile will be sent with postage
and/or other charges prepaid and properly           addressed to the party to be notified
at the address or facsimile number as           follows, or at such other address or
facsimile number as such other party may           designate by one of the indicated
means of notice herein to the other parties           hereto as follows:  

11 

                if
to the Secured Party, at 18881 VonKarman Avenue, Suite 330, Irvine, CA 92612; Facsimile: (949) 752-0223. 

                if
to the Grantor,  marked  "Attention:  President",  at 6175 Lusk Blvd.,  San Diego, Ca
92121; Facsimile: (858) 410-5306.  

[Signature pages
follow.] 

12 

        IN
WITNESS WHEREOF, each of the parties hereto has caused this Security Agreement to be
executed and delivered by its duly authorized officer on the date first set forth above. 

	ADDRESS OF GRANTOR	PFC Therapeutics, LLC
	
6175 Lusk Boulevard	/s/ Duane J. Roth
	San Diego, CA 92121	Duane J. Roth, Manager
	

TAXPAYER IDENTIFICATION NUMBER OF 
GRANTOR	JURISDICTION OF ORGANIZATION OF 
GRANTOR
	
 	Delaware

[Signature Page to
Security Agreement] 

        IN
WITNESS WHEREOF, each of the parties hereto has caused this Security Agreement to be
executed and delivered by its duly authorized officer on the date first set forth above. 

SECURED PARTY: 

		Technology Gateway Partnership, L.P.
	
 	/s/ Thomas O. Gephart
		Thomas O. Gephart, Managing Partner of Ventana Capital Partners, LLC,
		the General Partner of Technology Gateway Partnership, L.P.

[Signature Page to
Security Agreement] 

SCHEDULE A 

LOCATION OF COLLATERAL 

	ENTITY	ADDRESS
	
PFC Therapeutics, LLC    	6175 Lusk Blvd., San Diego, CA 92121

SCHEDULE B 

COLLATERAL OF
GRANTOR CONSISTING OF CHATTEL PAPER, INSTRUMENTS OR INVESTMENT PROPERTY 

SCHEDULE C 

DEPOSIT ACCOUNTS,
SECURITIES ACCOUNTS AND COMMODITY ACCOUNTS 

(Including Grantor, Type
of Account, Account Name, Account Number and Name of Institution/Intermediary) 

Beneficiary Bank Name
& Address: 

Beneficiary Bank Routing
Number: 

Beneficiary Account
Number: 

Beneficiary Name &
Address: 

SCHEDULE D 

INTELLECTUAL PROPERTYExhibit 4.3 

THIS SECURED CONVERTIBLE NOTE
(“NOTE”) HAS NOT BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION
UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “ACT”). IN ADDITION, THE NOTE
HAS NOT BEEN REGISTERED UNDER APPLICABLE STATE SECURITIES LAWS IN RELIANCE UPON EXEMPTIONS
PROVIDED UNDER SUCH LAWS. THE NOTE MAY NOT BE PLEDGED, SOLD OR TRANSFERRED IN THE ABSENCE
OF (1) AN EFFECTIVE REGISTRATION STATEMENT COVERING THE SHARES FILED UNDER THE ACT, (2) AN
OPINION OF QUALIFIED COUNSEL, WHICH OPINION AND COUNSEL ARE SATISFACTORY TO THE
MANAGEMENT, THAT REGISTRATION IS NOT REQUIRED OR (3) OTHER EVIDENCE SATISFACTORY TO THE
MANAGEMENT THAT SUCH REGISTRATION IS NOT REQUIRED. 

SECURED CONVERTIBLE
NOTE 

	$500,000	November 20, 2003 
		San Diego, California 

For value received PFC Therapeutics,
LLC, a Delaware limited liability company (“Payor”) promises to pay to
Technology Gateway Partnership, L.P. or its assigns (“Holder”) the
principal sum of $500,000. 

    1.                     This
note (the “Note”) is referred to in and is executed and
          delivered in connection with that certain Security Agreement executed by Payor
          in favor of the Holder (as the same may be amended, modified, supplemented or
          restated from time to time, the “Security Agreement”).
          Additional rights and obligations of Holder are set forth in the Security
          Agreement. The full amount of this Note is secured by the collateral identified
          and described as security therefor in the Security Agreement.  

    2.                     To
the extent applicable, upon consummation of a Financing (as defined below),           the
outstanding principal amount of this Note shall, at the option of the           Holder,
convert into an equity interest in the Payor on the terms of equity           portion (if
any) of the Financing. For purposes of this Note, “Financing” means a
financing pursuant to which the Payor           receives gross proceeds of $10,000,000
(or such other amount approved by the           Holder) from one or more investors,
strategic partners, or other sources (or any           combination of the foregoing). By
way of example, the equity financing           contemplated by the Term Sheet dated
November 7, 2003 by and among Alliance           Pharmaceutical Corp. (“Alliance”)
and SRS Capital-West, Inc.           (as the same may be amended, modified, supplemented
or restated from time to           time) would be a Financing under this Note.  

    3.                     In
the event this Note is not converted in connection with a Financing, Alliance
          shall, pursuant to an amendment to the Guaranty and Security Agreement executed
          by Alliance in favor of Holder (as the same may be amended, modified,
          supplemented or restated from time to time), irrevocably, absolutely and
          unconditionally collaterally assign to the Holder, as full repayment of this
          Note, 100% of the Earnout (as defined below), up to an aggregate maximum amount
          of $1,500,000, to be paid to Oxygent Creditors (as defined in the Asset
Purchase           Agreement (as defined below)) after January 1, 2006 pursuant to
Section 1.3 of           that certain Asset Purchase Agreement dated June 18, 2003 by and
between           Alliance and Photogen Technologies, Inc (the “Asset Purchase
          Agreement”). For purposes of this Note, the term “Earnout” means
the right of Alliance to receive royalty           payments from the sale of ImagentTM products
pursuant to the Asset Purchase           Agreement.  

1 

    4.                     In
the event of any default hereunder, Payor shall pay all reasonable           attorneys’ fees
and court costs incurred by Holder in enforcing and           collecting this Note.  

    5.                     If
there shall be any Event of Default hereunder, at the option and upon the
          declaration of the Holder of this Note and upon written notice to the Payor
          (which election and notice shall not be required in the case of an Event of
          Default under Section 7(c) or 7(d)), this Note shall accelerate and all
          principal and unpaid accrued interest shall become due and payable. The
          occurrence of any one or more of the following shall constitute an Event of
          Default:  

            (a)                     Payor
shall default in its performance of any covenant under the Security           Agreement
and such default is not cured within thirty (30) days following notice           to Payor
of such default;  

            (b)                     Payor
files any petition or action for relief under any bankruptcy,           reorganization,
insolvency or moratorium law or any other law for the relief of,           or relating
to, debtors, now or hereafter in effect, or makes any assignment for           the
benefit of creditors or takes any corporate action in furtherance of any of           the
foregoing; or  

            (c)                     An
involuntary petition is filed against Payor (unless such petition is           dismissed
or discharged within thirty (30) days) under any bankruptcy statute           now or
hereafter in effect, or a custodian, receiver, trustee, assignee for the
          benefit of creditors (or other similar official) is appointed to take
          possession, custody or control of any property of Payor.  

    6.                     Payor
hereby waives demand, notice, presentment, protest and notice of dishonor.  

    7.                     This
Note is exempt from California usury laws by reason of California           Corporations
Code Section 25118. Notwithstanding any provision of this Note,           Payor shall not
and will not be required to pay interest at a rate or any fee or           charge in an
amount prohibited by applicable law. If interest or any fee or           charge payable
on any date would be prohibited, then such interest, fee or           charge will be
automatically reduced to the maximum amount that is not           prohibited. In the
event that Holder receives payment of any interest, fee, or           charge that would
cause the amount so received to exceed the maximum amount           permitted under
applicable law, then, to the extent that the amount so received           exceeds the
maximum amount permitted under applicable law: (a) in the first           instance, the
amount received shall be applied to principal and (b) in the           second instance,
in the event that the principal amount of this Note has been           paid in full, the
remaining amount so received shall be deemed to be a loan from           Payor to Holder,
repayable upon the demand of the Payor with interest at the           legal rate from the
date of Holder’s receipt of each payment in excess           interest, fees, or
charges.  

    8.                     This
Note shall be governed by and construed under the laws of the State of
          California, as applied to agreements among California residents, made and to be
          performed entirely within the State of California, without giving effect to
          conflicts of law principles.  

2 

    9.                     Any
term of this Note (or any Event of Default hereunder) may be amended or           waived
with the written consent of Payor and Holder.  

		PFC THERAPEUTICS, LLC
	
 	/s/ Duane J. Roth
		Duane J. Roth, Manager
	

 	ACKNOWLEDGED AND AGREED:
	
 	ALLIANCE PHARMACEUTICAL CORP.
	
 	/s/ Duane J. Roth
		Duane J. Roth, Chairman and CEO

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