UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D
                    Under the Securities Exchange Act of 1934
                               (Amendment No. 5)*



                                  ICAGEN, INC.
- --------------------------------------------------------------------------------
                                (Name of Issuer)

                    Common Stock, par value $0.001 per share
- --------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    45104P104
- --------------------------------------------------------------------------------
                                 (CUSIP Number)


                                         with copy to:
Xmark Opportunity Partners, LLC          Lowenstein Sandler PC
90 Grove Street, Suite 201               1251 Avenue of the Americas, 18th Floor
Ridgefield, Connecticut 06877            New York, New York 10020
Attention: Ms. Mary L. King              Attention: Peter D. Greene, Esq.
(203) 244-9503                           (646) 414-6908
- --------------------------------------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)


                                January 13, 2010
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             (Date of Event which Requires Filing of this Statement)



If the filing person has previously  filed a statement on Schedule l3G to report
the  acquisition  that is the subject of this  Schedule  13D, and is filing this
schedule because of Sections 240.13d-1(e),  240.13d-1(f) or 240.13d-1(g),  check
the following box. [ ]

Note:  Schedules  filed in paper format shall include a signed original and five
copies of the schedule,  including all exhibits. See Section 240.13d-7 for other
parties to whom copies are to be sent.

*The  remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for  any  subsequent   amendment   containing   information  which  would  alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be filed for the purpose of Section 18 of the Securities Exchange Act of 1934
("Act") or otherwise  subject to the  liabilities of that section of the Act but
shall be subject to all other provisions of the Act (however, see the Notes).





Cusip No.     45104P104
- --------------------------------------------------------------------------------
1)   Names of Reporting  Persons.  I.R.S.  Identification  Nos. of above persons
     (entities only):

                 Xmark Opportunity Partners, LLC
                 20-2052197
- --------------------------------------------------------------------------------
2)   Check the Appropriate Box if a Member of a Group (See Instructions):

            (a)               Not
            (b)            Applicable

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3)   SEC Use Only

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4)   Source of Funds (See Instructions):   AF, WC

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5)   Check if Disclosure of Legal Proceedings is Required Pursuant to Items 2(d)
     or 2(e):
                    Not Applicable
- --------------------------------------------------------------------------------
6)   Citizenship or Place of Organization:   United States

- --------------------------------------------------------------------------------
     Number of                          7)  Sole Voting Power:        2,095,996*
                                            ------------------------------------
     Shares Beneficially                8)  Shared Voting Power:
                                            ------------------------------------
     Owned by
     Each Reporting                     9)  Sole Dispositive Power:   2,095,996*
                                            ------------------------------------
     Person With                       10)  Shared Dispositive Power:
                                            ------------------------------------
- --------------------------------------------------------------------------------
11)  Aggregate Amount Beneficially Owned by Each Reporting Person:    2,095,996*

- --------------------------------------------------------------------------------
12)  Check  if  the  Aggregate  Amount in  Row (11) Excludes Certain Shares (See
     Instructions):
                      Not Applicable
- --------------------------------------------------------------------------------
13)  Percent of Class Represented by Amount in Row (11):     4.4%*

- --------------------------------------------------------------------------------
14)  Type of Reporting Person (See Instructions):  IA

- --------------------------------------------------------------------------------
* Xmark Opportunity Partners, LLC ("Opportunity Partners") is the sole member of
the  investment  manager of Xmark  Opportunity  Fund,  L.P., a Delaware  limited
partnership  ("Opportunity  LP"),  and Xmark  Opportunity  Fund,  Ltd., a Cayman
Islands exempted company ("Opportunity Ltd"), and, as such, possesses sole power
to vote and direct the disposition of all securities of Icagen, Inc., a Delaware
corporation (the  "Company"),  held by Opportunity LP and Opportunity Ltd. David
C.  Cavalier  and Mitchell D. Kaye,  the  Co-Managing  Members of Xmark  Capital
Partners,  LLC, the Managing  Member of Opportunity  Partners,  share voting and
investment  power  with  respect  to  all  securities   beneficially   owned  by
Opportunity Partners.

As of January 26,  2010,  Opportunity  LP held 596,859  shares of Common  Stock,
$0.001 par value per share (the "Common Shares"), of the Company and Opportunity
Ltd held  1,499,137  Common Shares of the Company.  Based upon  information  set
forth in the Company's most recent  Quarterly Report on Form 10-Q, as filed with
the  Securities  and  Exchange  Commission  on  November  9,  2009,  there  were
47,182,222  Common  Shares of the Company  deemed issued and  outstanding  as of
January 26, 2010.  As a result of the  foregoing,  for purposes of Reg.  Section
240.13d-3,  Opportunity  Partners is deemed to beneficially own 2,095,996 Common
Shares of the Company, or 4.4% of the Common Shares of the Company deemed issued
and outstanding as of January 26, 2010.  Opportunity  Partners's interest in the
securities reported herein is limited to the extent of its pecuniary interest in
Opportunity LP and Opportunity Ltd, if any.





Item 5.   Interest in Securities of the Issuer.
          ------------------------------------

          Item 5 is hereby  amended by deleting  Item 5 in its  entirety  and by
substituting the following in lieu thereof:

          Based  upon  information  set  forth  in  the  Company's  most  recent
Quarterly  Report  on Form  10-Q,  as filed  with the  Securities  and  Exchange
Commission  on  November 9, 2009,  there were  47,182,222  Common  Shares of the
Company deemed issued and outstanding as of January 25, 2010.

          As of January 26, 2010,  Opportunity  LP held 596,859 Common Shares of
the Company and Opportunity Ltd held 1,499,137 Common Shares of the Company.

          Opportunity  Partners  possesses  sole  power to vote and  direct  the
disposition  of all  securities  of  the  Company  held  by  Opportunity  LP and
Opportunity  Ltd.  Messrs.  Cavalier and Kaye share voting and investment  power
with respect to all securities beneficially owned by Opportunity Partners.

          As a result of the foregoing,  for purposes of Reg. Section 240.13d-3,
Opportunity  Partners is deemed to beneficially  own 2,095,996  Common Shares of
the  Company,  or 4.4% of the Common  Shares of the  Company  deemed  issued and
outstanding as of January 26, 2010. As of January 15, 2010, Opportunity Partners
ceased to be the beneficial owner of more than 5% of the Company's Common Shares
deemed issued and outstanding as of January 15, 2010.

          The following  table details all of the  transactions in Common Shares
of the Company, or securities  convertible into, exercisable for or exchangeable
for Common Shares of the Company,  by the persons  referenced in Item 2 (each of
which were effected by Opportunity LP and Opportunity Ltd in ordinary  brokerage
transactions), during the sixty (60) day period occurring on or prior to January
26, 2010:



                    Type of           Number                          Price per
     Date         Transaction       of Shares      Security Type      Share ($)
     ----         -----------       ---------      -------------      ----------

   1/11/2010         Sale             78,171       Common Shares      $0.7297
   1/12/2010         Sale             55,000       Common Shares      $0.7302
   1/13/2010         Sale            569,800       Common Shares      $0.9421
   1/14/2010         Sale             87,861       Common Shares      $1.0001
   1/15/2010         Sale            192,000       Common Shares      $0.9094
   1/19/2010         Sale             15,200       Common Shares      $0.9500
   1/20/2010         Sale             82,000       Common Shares      $0.9518
   1/21/2010         Sale             54,000       Common Shares      $0.9394
   1/22/2010         Sale             12,107       Common Shares      $0.9500
   1/25/2010         Sale             41,300       Common Shares      $0.9483
   1/26/2010         Sale             15,000       Common Shares      $0.9320






                                    Signature
                                    ---------

          After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information  set forth in this statement is true,  complete and
correct.


January 26, 2010                              XMARK OPPORTUNITY PARTNERS, LLC
                                              By:  XMARK CAPITAL PARTNERS, LLC,
                                                   its Managing Member

                                              By:     /s/ David C. Cavalier
                                                 -------------------------------
                                              Name:    David C. Cavalier
                                              Title:   Co-Managing Member



      ATTENTION: INTENTIONAL MISSTATEMENTS OR OMISSIONS OF FACT CONSTITUTE
               FEDERAL CRIMINAL VIOLATIONS (SEE 18 U.S.C. 1001).