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                                                                  EXHIBIT 10.12B


                       AGREEMENT FOR PURCHASE AND SALE
                                OF TECHNOLOGY


        THIS AGREEMENT is entered into as of the 16 day of January, 1993, by
and between LASER ATLANTA OPTICS, INC., a Georgia corporation ("Seller"); and
SPECTRX, INC., a Delaware corporation ("Purchaser").




                             W I T N E S S E T H:


        WHEREAS, the parties have entered into a certain agreement dated
November 6, 1992 entitled "TECHNOLOGY PURCHASE AND TRANSFER AGREEMENT" (such
agreement being hereinafter referred to as the "Prior Agreement"), the terms of
which are incorporated herein by reference; and

        WHEREAS, the parties desire to enter into this Agreement in order to
clarify the terms of the Prior Agreement and to add additional terms which were 
agreed to at the time of the Prior Agreement but were not included in the terms 
of the Prior Agreement;

        NOW THEREFORE, for and in consideration of the premises and mutual
promises, representations, warranties, covenants and agreements contained
herein, the parties do hereby covenant, agree, represent, warrant and stipulate 
as follows:


        1.      PURCHASE AND SALE OF TECHNOLOGY.  Upon the terms and
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subject to the conditions contained herein, Purchaser hereby agrees to purchase
and Seller hereby agrees to sell all of Seller's right, title and interest in
and to the technology, patents, software, designs, models, drawings, know-how,
trademarks, trade names, service marks (including the goodwill associated with
the trademarks, trade names and service marks), trade secrets, copyrights and
registrations and applications therefor, relating to non-invasive means of
diagnosing disease through the use of fluorescence spectroscopy (the "Assets"). 
The Assets shall include, without limitation, Seller's rights in and to that
certain license agreement dated May 7, 1991, between Georgia Tech Research
Corporation and Seller, a copy of which is attached hereto as Exhibit A (the
"License Agreement").  In addition, the Assets shall include any and all books,
records, computer tapes or disks, flow diagrams, specification sheets, source
codes, and object codes relating to the Assets, and other physical
manifestations of the Assets.

        2.      PURCHASE PRICE.  The price to be paid by Purchaser for the
Assets at Closing (as hereinafter defined) shall be $100,000.00 and shall be
payable by delivery of a promissory note in the form attached hereto as Exhibit
B and made a part hereof (the "Promissory Note").  The Promissory Note shall be
secured by a patent collateral assignment and security agreement in the form of
Exhibit C attached hereto and made a part hereof (the "Security Agreement")
conveying a security interest in the Assets to Seller.



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        3.      WARRANTIES AND REPRESENTATIONS.  Seller represents and warrants
to Purchaser as follows:

                3.1     Authority.  Seller is a corporation duly organized,
        validly existing and in good standing under the laws of the State of
        Georgia and has all requisite corporate power and authority and, except
        for the consent of Georgia Tech Research Corporation, all authorizations
        necessary to enter into this Agreement and to carry out the transactions
        contemplated hereby.

                3.2     Ownership of Assets.  Seller owns and controls all of
        the Assets free and clear of all liens, claims, charges and any other 
        defects in title of any nature whatsoever.

                3.3     Infringement.  To the best of Seller's knowledge,
        without investigation, no aspect of the Assets infringes upon any 
        proprietary rights of any other person, firm, corporation or other 
        legal entity and there is not pending or, to the best of Seller's 
        knowledge, without investigation, threatened any claim or litigation
        against Seller regarding the Assets, nor to the best of Seller's 
        knowledge, without investigation, is there any basis for such claim.

        4.      CLOSING.  The consummation of the transactions contemplated
herein (the "Closing") shall be held at such time and place designated by
Purchaser but in no event later than January 31,



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1993.  At the Closing, Seller shall deliver to Purchaser the Assets by virtue
of delivery of a certain assignment and bill of sale (the "Assignment") in
substantially the same form as Exhibit D attached hereto and made a part
hereof.  The Assignment shall be executed by Georgia Tech Research Corporation
in order to consent to the assignment of Seller's interest in the License
Agreement.  At the Closing, Purchaser shall deliver to Seller the Promissory
Note, the Security Agreement, and the Assignment.

     5.  CONDITION TO CLOSING.  Any provision to the contrary contained herein
notwithstanding, Purchaser's obligation to purchase the Assets at Closing is
contingent upon Seller's obtaining the consent of Georgia Tech Research
Corporation to the proposed Assignment.  Seller agrees to use its best efforts
in obtaining such consent prior to the Closing.

     6.  MISCELLANEOUS.

         6.1  Further Assurances.  Each party covenants that at any time, and
from time to time, after the Closing, it will execute such additional
instruments and take such actions as may be reasonably requested by the other
party to confirm, or perfect, or otherwise to carry out the intent and purpose
of this Agreement.

         6.2  Waiver.  Any failure on the part of any party hereto to comply
with any of its obligations, agreements, or


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conditions hereunder may be waived by any other party to whom such compliance
is owed.  No waiver of any provision of this Agreement shall be deemed, or
shall constitute, a waiver of any other provision, whether or not similar, nor
shall any waiver constitute a continuing waiver.

     6.3  Severability.  In the event that any provision of this Agreement or
any word, phrase, clause, sentence, or other portion thereof, shall be
unenforceable or invalid for any reason, such provision or portion thereof
shall be modified or deleted in such a manner so as to make this Agreement, as
modified, legal and enforceable to the fullest extent permitted under
applicable laws.

     6.4  Binding Effect.  This Agreement shall be binding upon and inure to
the benefit of the parties hereto and their respective successors and assigns. 
No party may assign this Agreement, in whole or in part, without the prior
express written consent of the other party.

     6.5. Entire Agreement.  This Agreement and the Prior Agreement constitute
the entire agreement between the parties hereto and supersede and cancel any
prior agreements, representations, warranties or communications, whether oral
or wrtiten, between the parties hereto relating to the transactions contemplated
hereby, or the subject matter


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hereof.  This Agreement may not be changed, waived, discharged or terminated
orally, but only by an agreement in writing signed by the parties hereto.  In
the event of a discrepancy between the terms of this Agreement and the Prior
Agreement, the terms of this Agreement shall control.

      6.6  Governing Law.  This Agreement shall be governed by and construed in
accordance with the laws of the State of Georgia.

      6.7  Disclaimer.  EXCEPT AS EXPRESSLY PROVIDED HEREIN, SELLER DISCLAIMS
ANY AND ALL EXPRESS OR IMPLIED WARRANTIES REGARDING THE ASSETS AND THE
UNDERLYING TECHNOLOGY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, AND PURCHASER ACKNOWLEDGES
THAT, EXCEPT AS EXPRESSLY PROVIDED HEREIN, IT IS ACQUIRING THE ASSETS AND THE
UNDERLYING TECHNOLOGY ON AN "AS IS", "WHERE IS", AND "WITH ALL FAULTS" BASIS. 
NEITHER SELLER NOR PURCHASER SHALL BE LIABLE FOR ANY INDIRECT OR CONSEQUENTIAL
DAMAGES.



                       (Signatures begin on next page)



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     IN WITNESS WHEREOF, Purchaser and Seller have caused this Agreement to be
executed as of the date first above written.


                                           "SELLER"
                                           Laser Atlanta Optics, Inc.
                                           By: /s/ Mark A. Samuels
                                               --------------------------
                                               Mark A. Samuels, President 

                                           "PURCHASER"
                                           Spectrx, Inc.
                                           By: /s/ Mark A. Samuels
                                               --------------------------
                                               Mark A. Samuels, President



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                                                                      EXHIBIT A


                              LICENSE AGREEMENT


                                   OMITTED


                              PLEASE SEE EXHIBIT


                                    10.12A


                                    BELOW
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                                                                       EXHIBIT B

                                 SECURED NOTE

$100,000.00                     Atlanta, Georgia                January___, 1993


        FOR VALUE RECEIVED, the undersigned promises to pay to the order of
LASER ATLANTA OPTICS, INC.,  a Georgia corporation, the principal sum of ONE
HUNDRED THOUSAND ($100,000.00) AND NO/100 DOLLARS, in legal tender of the
United States, with interest thereon from date at the rate of zero per centum
(0.0%) per annum, on the unpaid balance until paid, as follows:

        One installment of One Hundred Thousand Dollars ($100,000.00 on or
        before January 31, 1993; or

        One installment of One Hundred One Thousand Dollars ($101,000.00) after
        January 31, 1993, but before February 28, 1993.

        Principal and interest are payable at Atlanta, Georgia, or at such
other place as the holder thereof may designate in writing.
        
        Should any installment not be paid when due, or should the maker, or
makers, hereof fail to comply with any of the terms or requirements of a patent
collateral assignment and security agreement of even date herewith, conveying a
security interest in certain properties as security for this indebtedness, the
entire unpaid principal sum evidenced by this Note (i.e., $101,000.00), with
all accrued interest, shall, at the option of the holder, and without notice to
the undersigned, become due and may be collected forthwith, time being of the
essence of this contract.  It is further agreed that failure of the holder to
exercise this right of accelerating the maturity of the debt, or indulgence
granted from time to time, shall in no event be considered as a waiver of such
right of acceleration or estop the holder from exercising such right.

        In case this Note is collected by law, or through an attorney at law,
all costs of collection, including fifteen per centum (15%) of the principal
and interest as attorney's fees, shall be paid by the makers hereof.

        And each of us, whether maker, endorser, guarantor, or surety, hereby
severally waives and renounces, for himself and family, any and all
exemption rights either of us, or the family of either of us, may have under 
or by virtue of the Constitution or laws of Georgia, or any other
State, or the United States, as against this debt or any renewal thereof; and
each further waives demand, protest and notice of demand, protest and
non-payment.



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        In case of default in the payment of the amounts due hereunder by
February 28, 1993, said principal sum (i.e., $101,000.00), or so much thereof
as may remain unpaid at the time of such default, shall bear interest at the
rate of eighteen per centum (18%) per annum from the date of such default.

        This contract is to be construed in all respects and enforced according
to the laws of the State of Georgia.

Prepayment Privilege:

        This Note may be prepaid at any time without penalty or charge.



Witness the hand of our                         SPECTRX, INC.
duly authorized officer.

                                                By:
                                                   ----------------------------
                                                   Mark A. Samuels, President
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                                                                      EXHIBIT C

                                PURCHASE MONEY
                         PATENT COLLATERAL ASSIGNMENT
                            AND SECURITY AGREEMENT

        This Agreement is made on the ______ day of January, 1993, between
SPECTRX, INC., a Delaware corporation ("Assignor") and LASER ATLANTA OPTICS,
INC., a Georgia corporation ("Lender").

                             W I T N E S S E T H

        WHEREAS, Lender has assigned, conveyed, and transferred to Assignor all
of its right to certain assets by virtue of its execution and delivery of a
certain Assignment and Bill of Sale of even date herewith (the "Assignment"),
the terms of which are incorporated herein by this reference; and

        WHEREAS, Assignor has executed and delivered its purchase money
promissory note (the "Note") of even date herewith to the Lender in the
principal amount of $100,000.00; and, in order to induce the Lender to accept
the Note, Assignor has agreed to assign to Lender certain patent rights and
other property acquired through the Assignment.

        NOW, THEREFORE, in consideration of the foregoing and the premises
herein contained, Assignor hereby agrees with Lender as follows:

        1.   To secure the complete and timely satisfaction of all obligations
of Assignor under the Note (the "Obligations"), Assignor hereby grants, assigns
and conveys to Lender all of its rights, title and interest, resulting from the
Assignment to:

             a)   all right, title and interest in and to the technology,
patents, software, designs, models, drawings, know-how, trademarks, trade
names, and service marks (including the goodwill associated with the
trademarks, trade names and service marks), trade secrets, copyrights,
registrations and applications therefor, relating to non-invasive means of
diagnosing disease through the use of flourescence spectroscopy, including,
without limitation, any and all books, records, computer tapes or disks, flow
diagrams, specifications sheets, source codes, and object codes relating to the
foregoing and other physical manifestations of the foregoing; and

             b)   all right, title, interest, powers, privileges and options in
and to, and in accordance with, that certain license agreement dated May 7,
1991, by and between GEORGIA TECH RESEARCH CORPORATION and Seller,

including without limitation, all proceeds thereof (such as, by way of example,
license royalties and proceeds of infringement suits), the right to sue for
past, present and future infringements, and  
        
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all rights corresponding thereto (collectively called the "Assets").

     2.  Assignor agrees that, until all of the Obligations shall have been
satisfied in full, it will not enter into any agreement (for example, a license
agreement) which is inconsistent with Assignor's obligations under this
Agreement, without Lender's prior written consent.

     3.  Unless and until there shall have occurred and be continuing a breach
of the Obligations, Lender hereby grants to Assignor the exclusive,
non-transferable right, license, and use of and to the Assets, provided,
however, Assignor agrees not to sell, assign, or otherwise encumber its
interest in, or grant any sublicense under the Assets, or any part thereof,
without the prior written consent of Lender.

     4.  If any breach of the Obligations shall have occurred and be 
continuing, Assignor's rights, license, and use of and to the Assets set forth
in Section 3, shall terminate forthwith, and the Lender shall have, in addition
to all other rights and remedies given it by this Agreement, those allowed by
law and the rights and remedies of a secured party under the Uniform Commercial
Code as enacted in any jurisdiction in which the Assets may be located and,
without limiting the generality of the foregoing, the Lender may immediately,
without demand or performance and without other notice (except as set forth
next below) or demand whatsoever to Assignor, all of which are hereby expressly
waived, and without advertisement, sell at public or private sale or otherwise
realize upon, in Atlanta, Georgia, or elsewhere, the whole or from time to time
any part of the Assets, or any interest which the Assignor may have therein,
and after deducting from the proceeds of sale or other disposition of the
Assets all expenses (including all reasonable expenses for brokers' fees and
legal services), shall apply the residue of such proceeds toward the
satisfaction of the obligations.  Any remainder of the proceeds after
satisfaction in full of the Obligations shall be paid over to the Assignor. 
Notice of any sale or other disposition of the Assets shall be given to
Assignor at least five (5) days before the time of nay intended public or
private sale or other disposition of the Patents is to be made, which Assignor
hereby agrees shall be reasonable notice of such sale or other disposition. 
At any such sale or other disposition, any holder of the Note or Lender may, to
the extent permissable under applicable law, purchase the whole or any part of
the Assets sold, free from any right of redemption on the part of Assignor,
which right is hereby waived and released.

     5.  If any breach of the Obligations shall have occurred and be
continuing, Assignor hereby authorizes and empowers Lender to make, constitute
and appoint any officer or agent of Lender, as Lender may select in its
exclusive discretion, as Assignor's true and lawful attorney-in-fact, with the
power to endorse Assignor's


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name on all applications, documents, papers and instruments necessary for
Lender to use the Assets, or any part thereof, or to grant or issue any
exclusive or non-exclusive license under the Assets, or any part thereof, to
any third person, or necessary for Lender to assign, pledge, convey or
otherwise transfer title in or dispose of the Assets, or any part thereof, to
any third person.  Assignor hereby ratifies all that such attorney shall
lawfully do or cause to be done by virtue hereof.  This power of attorney is
coupled with an interest and shall be irrevocable for the life of this
Agreement.

     6.  At such time as Assignor shall completely satisfy all of the
Obligations, this Agreement shall terminate and Lender shall execute and
deliver to Assignor all deeds, assignments and other instruments as may be
necessary or proper to re-vest in Assignor full title to the Assets, subject to
any disposition thereof which may have been made by Lender pursuant hereto.

     7.  No course of dealing between Assignor and Lender, nor any failure to
exercise, nor any delay in exercising, on the part of Lender, any right, power
or privilege hereunder or under the Note shall operate as a waiver thereof; nor
shall any single or partial exercise of any right, power or privilege hereunder
or thereunder preclude any other or further exercise thereof or the exercise of
any other right, power or privilege.

     8.  All of Lender's rights and remedies with respect to the Assets,
whether established hereby or by the Note, or by any other agreements or by law
shall be cumulative and may be exercised singularly or concurrently.

     9.  The provisions of this Agreement are severable, and if any clause or
provision shall be held invalid and unenforceable in whole or in part in any
jurisdiction, then such invalidity or unenforceability shall affect only such
clause or provision, or part thereof, in such jurisdiction, and shall not in
any manner affect such clause or provision in any other jurisdiction, or any
other clause or provision of this Agreement in any jurisdiction.

    10.  This Agreement is subject to modification only by a writing signed by
the parties.

    11.  The benefits and burdens of this Agreement shall inure to the benefit
of and be binding upon the respective successors and permitted assigns of the
parties.

    12.  The validity and interpretation of this Agreement and the rights and
obligations of the parties shall be governed by the laws of the State of
Georgia.



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        WITNESS the execution hereof under seal as of the day and year first
above written.


                                                ASSIGNOR:

                                                Spectrx, Inc.


                                                By:
                                                   ----------------------------
                                                   Mark A. Samuels, President  


                                                LENDER  

                                                Laser Atlanta Optics, Inc.


                                                By:
                                                   ----------------------------
                                                   Mark A. Samuels, President  














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                                                                       EXHIBIT D


                         ASSIGNMENT AND BILL OF SALE


        THIS ASSIGNMENT AND BILL OF SALE (the "Assignment"), is made and
entered into as of the ______ day of January, 1993, by and between LASER
ATLANTA OPTICS, INC., a Georgia corporation ("Seller"), and SPECTRX, INC., a
Delaware corporation ("Purchaser").

        In consideration of and as a condition to the payment of One Hundred
Thousand and No/100 ($100,000.00) Dollars by Purchaser to Seller, the mutual
promises herein contained, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:


        1.      Seller does hereby convey, grant, sell, transfer, assign and
deliver unto Purchaser, its successors and assigns forever, all of Seller's
right, title and interest in and to the technology, patents, software, designs,
models, drawings, know-how, trademarks, trade names, service marks (including
the goodwill associated with the trademarks, trade names and service marks),
trade secrets, copyrights, registrations and applications therefor, relating to
non-invasive means of diagnosing disease through the use of fluorescence
spectroscopy, including, without limitation, any and all books, records,
computer tapes or disks, flow diagrams, specification sheets, source codes, and
object codes relating to the foregoing and other physical manifestations of the
foregoing (the "Assets").
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        2.  Seller hereby grants, assigns and conveys to Purchaser all of
Seller's right, title, interest, powers, privileges and options in and to, and
in accordance with, that certain license agreement dated May 7, 1991, by and
between GEORGIA TECH RESEARCH CORPORATION and Seller, a copy of which is
attached hereto as Exhibit A (the "License Agreement").  Purchaser does hereby
assume and agree to perform all of the duties and obligations of the Seller
under the License Agreement, effective from and after the date hereof.

        3.  SELLER DISCLAIMS ANY AND ALL EXPRESS OR IMPLIED WARRANTIES
REGARDING THE ASSETS, THE LICENSE AGREEMENT, AND THE UNDERLYING TECHNOLOGY
RELATING TO MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, AND PURCHASER
ACKNOWLEDGES THAT, EXCEPT AS EXPRESSLY PROVIDED IN THE AGREEMENT, IT IS
ACQUIRING THE ASSETS, THE LICENSE AGREEMENT, AND THE UNDERLYING TECHNOLOGY ON
AN "AS IS", "WHERE IS", AND "WITH ALL FAULTS" BASIS.  NEITHER SELLER NOR
PURCHASER SHALL NOT BE LIABLE FOR ANY INDIRECT OR CONSEQUENTIAL DAMAGES.

        4.  Purchaser and Seller each agree that it will execute such
additional instruments and take such actions as may be reasonably requested by
the other party to confirm, or perfect, or otherwise carry out the intent and
purpose of this Assignment.

        5.  This Assignment shall be binding and shall inure to the benefit of
Seller and Purchaser and their respective successors and 


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assigns.                                  

        IN WITNESS WHEREOF, Purchaser and Seller have caused this Assignment to
be executed by their duly executed officers as of the date first above written.

                                            "SELLER"                      

                                            Laser Atlanta Optics, Inc.    

                                            By:                           
                                               ---------------------------
                                               Mark A. Samuels, President 
                                                                          
                                            "PURCHASER"                    

                                            Spectrx, Inc.                 

                                            By:                           
                                               ---------------------------
                                               Mark A. Samuels, President 

        In order to consent to the assignment of the License Agreement pursuant
to Section 2 above, and for no other purposes, the undersigned has hereunto
executed this Assignment this   day of January, 1993.

                                           GEORGIA TECH RESEARCH CORPORATION   

                                           By:                                 
                                              ---------------------------      
                                           Name:                               
                                                -------------------------      
                                           Title:                              
                                                 ------------------------      
                                                                               
                                           By:                                 
                                              ---------------------------      
                                           Name:                               
                                                -------------------------      
                                           Title:                              
                                                 ------------------------      





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