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EXHIBIT 10.1

                                                               December 30, 2005

Mr. Fredrick B. Rolff
250 East 63rd Street
Apt. 1101
New York, NY 10021


      Re: Separation from Sentigen Holding Corp.

Dear Fred:

      In connection with the termination, effective March 31, 2006, of your
employment with Sentigen Holding Corp. (the "Company"), this letter will confirm
our following agreement:

      1. Your employment with the Company will terminate on March 31, 2006 (the
"Termination Date"). You hereby resign as Chief Financial Officer of the Company
and its subsidiaries effective as of December 31, 2005. From and after December
31, 2005, your duties and responsibilities shall consist solely of those that
may be reasonably requested of you from time to time by the Company's Chief
Executive Officer (the "CEO") or Chief Financial Officer (the "CFO"). It is
understood that no commitment is made by the Company as to the amount or level
of your duties and responsibilities, and that your obligations shall arise, if
at all, only if, as and when requested by the CEO or the CFO. You agree not to
take any actions for or on behalf of the Company, nor bind the Company, in any
way, except with the prior written consent of the CEO or the CFO. It is further
understood that, from and after December 31, 2005 you shall not be prohibited
from seeking full-time employment with another employer and that the Company
recognizes that your duties hereunder shall not interfere with such full-time
employment. Nonetheless, in the event that after December 31, 2005, you obtain
full-time employment, you agree to make yourself available when reasonably
requested by the CEO or CFO from time to time hereunder.

      2. You will continue to be paid your annual base salary of $150,000 now in
effect through the Termination Date, less withholding requirements required by
law or agreed to by you, payable in installments at such times as the Company
customarily pays its other employees (but in any event no less often then
monthly) for so long as you are in compliance with the terms of this agreement.

      3. You will be paid an $18,000 bonus for the year ending December 31, 2005
on the date hereof.


      4. For so long as you are in compliance with the terms of this Agreement,
you will continue to receive any employee benefits you were receiving as of the
date hereof through the Termination Date, to the extent such benefits continue
to remain available to employees of the Company, including but not limited to,
participation in the Company's 401(k) plan, dental, major medical and any other
health insurance that was in place as of the date hereof, provided, however,
that to the extent the Company changes its health care provider after the date
hereof, you shall be entitled to receive health care benefits from such new
health care provider through the Termination
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Date. You will also continue to receive a $500 monthly car allowance through the
Termination Date. Notwithstanding anything to the contrary contained herein, you
covenant to promptly notify the Company if you become eligible for dental, major
medical or any other health insurance coverage from another employer upon which
time your coverage under the Company's plan relating thereto shall cease.

      5. Your stock options to purchase 50,000 shares granted to you pursuant to
the Company's 2000 Performance Equity Plan which are currently vested and
exercisable shall be exercisable for 60 days following the Termination Date and
shall terminate on the day immediately following the 60 day anniversary of the
Termination Date.

      6. In consideration of the foregoing, you agree that the voluntary
payments set forth above are given to you in return for your discharge and
release of all claims, obligations, and demands which you have, ever had, or in
the future may have against the Company, Sentigen Biosciences, Inc., Cell &
Molecular Technologies, Inc. and any of their officers, directors, employees, or
agents, arising up to the date of this Release, including, but not limited to,
claims under Title VII of the Civil Rights Act of 1964, the Fair Labor Standards
Act, the New York Executive Law, the Administrative Code of the City of New
York, the New Jersey Law Against Discrimination, the Civil Rights Act of 1991,
the Age Discrimination in Employment Act, the Older Workers Benefits Protection
Act, the Employee Retirement Income Security Act of 1974, the Americans With
Disabilities Act, and all other federal, state, and local discrimination laws,
and claims for wrongful discharge. You further waive and release any claimed
right to reemployment, or employment with the Company, Sentigen Biosciences,
Inc. or Cell & Molecular Technologies, Inc. after the Termination Date. You do
not, however, waive or release any claims which arise after the date that you
execute this agreement.

      7. The Company has advised you to consult with an attorney and/or
governmental agencies prior to executing this agreement. By executing this
agreement you acknowledge that you have been provided an opportunity to consult
with an attorney or other advisor of your choice regarding the terms of this
agreement and that you have elected to enter into this agreement knowingly and
voluntarily.

      8. You acknowledge that, during the course of your employment with the
Company, you had access to confidential and proprietary information, documents
and other materials relating to the Company which are not generally known to
persons outside the Company and confidential information, documents and other
materials entrusted to the Company by third parties, including, without
limitation, financial information, trade secrets, technology, research,
developments, improvements, methods, procedures, discoveries, techniques,
know-how, marketing and other business plans, customer lists, data, strategies
and forecasts, and the substance of arrangements and agreements with customers,
suppliers and others (collectively, "Confidential Information"). Any
Confidential Information conceived or developed by you during the period of your
employment is the exclusive property of the Company. Except as specifically
authorized by the Company, you will not disclose Confidential Information to any
third person, firm or entity or use Confidential Information for your own
purposes or for the benefit of any third person, firm or entity other than (1)
as may be legally required in response to any summons, order or subpoena issued
by a court or governmental agency, provided that you first provide the Company
prompt notice of any requirement, full and complete cooperation to seek an
appropriate order or remedy and will only
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disclose that portion of the Confidential Information legally required to be
disclosed, or (2) Confidential Information which is or becomes available to the
general public through no act or failure to act by you. By executing this letter
below you represent that as of the Termination Date, you will have returned all
property of the Company, including but not limited to, any computers,
telephones, documents, books, records (whether in electronic format or hard
copy), reports, files, correspondence, notebooks, manuals, notes,
specifications, mailing lists, credit cards and data in your possession or
control. You acknowledge that money damages are an inadequate remedy for the
irreparable harm that may be suffered by breach of this section because of the
difficulty of ascertaining the amount of damage that will be suffered by the
Company. Therefore, you agree that the Company may, in addition to any other
available remedy, obtain specific performance of this section and injunctive
relief against any breach or threatened breach hereof without the necessity of
proving actual damages or posting a bond and that you shall not oppose the
granting of such relief.

      9. You acknowledge that this agreement and your Stock Option Agreement,
dated December 20, 2000, with the Company, set forth the entire agreement
concerning the subject matter hereof and may not be changed without the prior
written consent of each of you and the Company.

      10. This agreement shall be governed by the laws of the State of New York,
without giving effect to any principles of conflicts of law.

      11. This agreement may be executed in multiple counterparts, each of which
shall be an original, but all of which together shall constitute one instrument.

      Please confirm your acceptance of the terms of this letter by signing and
dating it and returning it to us.

                                    Very truly yours,

                                    SENTIGEN HOLDING CORP.


                                    By:  /s/ Joseph K. Pagano
                                         --------------------------
                                    Name:  Joseph K. Pagano
                                    Title: Chairman of the Board, Chief
                                           Executive Officer

ACCEPTED AND AGREED TO:

/s/ Frederick B. Rolff
-------------------------------
Name: Frederick B. Rolff