Document:

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                                                            EXHIBIT 10.30(1a)

                 FIRST AMENDMENT TO THE 7.5 % SECURED NOTE

          FIRST AMENDMENT, dated as of December 30, 1999 (this "First
Amendment"), to the 7.5% Secured Note (the "Note") issued by Bio-Plexus,
Inc. (the "Company") to Appaloosa Investment Limited Partnership I (the
"Holder") on October 21, 1999.

                            W I T N E S S E T H:

          WHEREAS, the Company has issued the Note to the Holder;

          WHEREAS, the Company wishes to induce the Holder to make
additional loans to the Company pursuant to the 15% Secured Note (as
defined herein), and in furtherance thereof the Company and the Holder have
agreed to amend the Note, subject to the terms and conditions set forth
herein;

          NOW, THEREFORE, in consideration of the premises and mutual
covenants contained herein, the Company and the Holder hereby agree as
follows:

          1.   Defined Terms. Unless otherwise defined herein, capitalized
terms which are defined in the Note are used herein as therein defined.

          2.   Amendment to Note.

          (a)  Subsection 1.4 of the Note is amended by deleting the first
sentence thereof in its entirety and substituting in lieu therefor the
following:

               The unpaid principal balance of this Note outstanding at any
               time shall accrue interest at a rate per annum equal to (i)
               from October 21, 1999 to the date preceding the date hereof,
               7.5% and (ii) from the date hereof, 12%, in each case
               including during the pendency of any bankruptcy or similar
               proceeding, whether or not a claim for post-petition
               interest is allowed as a claim in any such bankruptcy or
               proceeding.

          (b)  Subsection 1.5 of the Note is amended by deleting the
percentage at the end of the first sentence thereof and substituting in
lieu therefor the following:

               15% (including during the pendency of any bankruptcy or
               similar proceeding, whether or not a claim for post-petition
               interest is allowed as a claim in any such bankruptcy or
               proceeding)

          (c)  Subsection 3.2 of the Note is amended by adding the letter
"(a)" before the first sentence thereof and adding the following new
subsection (b):

               (b) The Board of Directors has taken all necessary action
<PAGE>   2
               so that no "fair price," "moratorium," "control share
               acquisition," "interested holder" or other similar anti-takeover
               statute or regulation (including, without limitation, Sections
               33-840 through 33-845 of the Connecticut Business Corporation
               Act) or any applicable anti-takeover provision in the Company's
               Certificate of Incorporation or By-Laws is applicable to the
               transactions contemplated by the Transaction Documents. To the
               knowledge of the Company, no other state takeover statute is
               applicable to the transactions contemplated by the Transaction
               Documents.

          (d)  Subsection 4.4 of the Note is amended by (i) deleting the
date at the end of the first clause of the first sentence thereof and
substituting in lieu therefor "February 28, 2000" and (ii) deleting the
period at the end of the first sentence thereof and substituting in lieu
therefor the following:

               ; provided, however, that the Company shall adjourn the
               Company Meeting from time to time until all of the
               conditions set forth in Section 6.2 are satisfied or waived
               (other than those conditions that by their nature are to be
               satisfied on the Rollover Date), such that the Company
               Meeting shall take place on the same day as the Rollover
               Date in accordance with Section 6.1.

          (e)  A new subsection 4.13 is added to the end of subsection 4.12:
               4.13 Security. The Secured Obligations have been, and will
               continue to be, secured by the Collateral, subject to the
               terms and conditions of the Collateral Documentation.

          (f)  Subsection 5.1(d) of the Note is amended by deleting all
references therein to "December 31, 1999" and substituting in lieu therefor
"February 28, 2000".

          (g)  Subsection 6.1 of the Note is amended by deleting the first
sentence thereof in its entirety and substituting in lieu therefor the
following:

               On the same day that the stockholders' approval referred to
               in Section 4.4 has been obtained (the "Rollover Date"),
               subject to Section 6.2, the Company and the Purchasers shall
               enter into (i) the Convertible Note Purchase Agreement
               attached as an exhibit to the Proxy Statement (the
               "Convertible Note Purchase Agreement"), (ii) warrants to
               purchase 1,500,000 shares of Common Stock at an exercise
               price of $7 attached as an exhibit to the Proxy Statement
               (the "Rollover Warrant"), (iii) the Registration Rights
               Agreement attached as an exhibit to the Proxy Statement (the
               "Rollover Registration Rights Agreement") and (iv) the
               Convertible Note Security Agreement attached as an exhibit
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               to the Proxy Statement (the "Convertible Note Security
               Agreement"); provided, however, that if a Governmental Entity
               shall determine that any of the transactions contemplated by the
               Rollover Transactions violate any applicable rules or regulations
               of such Governmental Entity, the Holder shall, at the Holder's
               sole discretion, either (i) abandon the Rollover Transactions or
               (ii) modify the structure of the Rollover Transactions in a
               manner to comply with such rule or regulation.

          (h)  Subsection 6.2(b) of the Note is amended by:

               (I)  adding the following phrase after the word "continuing"
                    in clause (ii) thereof:

                    "under this Note and no Default (as defined in the 15%
                    Secured Note) shall have occurred and be continuing
                    under the 15% Secured Note";

               (II) clause (iii) thereof shall be amended by adding the
                    following after the word "full":

                    "and the principal amount of the 15% Secured Note, plus
                    all accrued and unpaid interest on the 15% Secured
                    Note, shall have been repaid in full"; and

               (III)deleting clause (iv) thereof in its entirety and
                    renumbering the original clause (v) to clause (iv) and
                    clause (vi) to clause (v).

          (i)  Subsection 6.4 of the Note is amended by deleting the
reference to "December 31, 1999" and substituting in lieu therefor
"February 28, 2000"

          (j)  Subsection 7.1 of the Note is amended by (i) adding the
following definitions in proper alphabetical order:

               "15% Secured Note" means the 15% Secured Note in the initial
               aggregate principal amount of $1,650,000 to be issued by the
               Company to the Holder after the date hereof in accordance
               with the terms of the side letter, dated the date hereof,
               between the Company and the Holder, as such 15% Secured Note
               may be amended from time to time.

               "Note" shall mean this Note as amended hereby and from time
               to time in accordance with its terms.

and (ii) the definitions of "$3 Warrants," "$5 Warrants," "Maturity Date,"
"Registration Rights Agreement," "Rollover Transactions," "Transaction
Documents" and "Warrants" are deleted in their entirety and substituting in
lieu therefor the following definitions:

               "$3 Warrants" shall have the meaning ascribed thereto in
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               Section 2(e).

               "$5 Warrants" shall have the meaning ascribed thereto in
               Section 2(e).

               "Maturity Date" shall mean the earlier of February 28, 2000
               and the Rollover Date.

               "Registration Rights Agreement" shall have the meaning
               ascribed thereto in Section 6.4.

               "Rollover Transactions" shall mean the transactions
               contemplated by Section 6.1 of this Note.

               "Transaction Documents" shall mean this Note, the 15%
               Secured Note, the side letter, dated the date hereof,
               between the Company and the Holder, the Security Agreement,
               the Registration Rights Agreement, the warrants to be issued
               to Affiliates of the Holder pursuant to section (c) of the
               aforesaid side letter and the Warrants.

               "Warrants" shall have the meaning ascribed thereto in
               Section 2(e).

          (k)  Subsection 8.4 of the Note is amended by deleting it in its
entirety and substituting in lieu therefor the following:

               8.4. Entire Agreement. The Transaction Documents (including
               the Schedules and Exhibits thereto) contain the entire
               understanding of the parties with respect to the
               transactions contemplated hereby and thereby.

     3.   Representations and Warranties. The Company hereby confirms,
reaffirms and restates the representations and warranties set forth in
Section 3 of the Note. The Company represents and warrants that as of the
date hereof and, after giving effect to this First Amendment and the
transactions contemplated hereby, no Default or Event of Default has
occurred and is continuing.

     4.   Effectiveness. The First Amendment shall become effective as of the
date upon which the Holder receives the counterpart of this First Amendment
duly executed by the Company and a duly executed copy of the side letter,
dated the date hereof, between the Company and the Holder.

     5.   Continuing Effect of the Transaction Documents. This First
Amendment shall not constitute an amendment of any other provisions of the
Note or any other Transaction Documents not expressly referred to herein
and shall not be construed as a waiver or consent to any further or future
action on the part of the Company that would require a waiver or consent of
the Holder. Except as expressly amended hereby, the provisions of the
Note and the other Transaction Documents are and shall remain in full force
<PAGE>   5
and effect.

     6.   Counterparts. This First Amendment may be executed by the parties
hereto in any number of separate counterparts, each of which shall be
deemed to be an original, and all of which taken together shall be deemed
to constitute one and the same instrument.

     7.   GOVERNING LAW. THIS FIRST AMENDMENT SHALL BE GOVERNED BY, AND
CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW
YORK.

<PAGE>   6

     IN WITNESS WHEREOF, the parties hereto have caused this First
Amendment to be duly executed and delivered by their respective proper and
duly authorized officers as of the day and year first above written.

                                     BIO-PLEXUS, INC.

                                     By: /s/ Carl Sahi
                                        --------------------------------
                                        Name:  Carl Sahi
                                        Title:

                                     APPALOOSA INVESTMENT LIMITED
                                         PARTNERSHIP I

                                     By:  Appaloosa Management L.P., its
                                            General Partner
                                     By:  Appaloosa Partners Inc., its General
                                            Partner

                                     By: /s/ James E. Bolin
                                        --------------------------------
                                        Name:  James E. Bolin
                                        Title: Vice President<PAGE>   1
                                                               Exhibit 10.30(2a)

                 SECOND AMENDMENT TO THE 7.5 % SECURED NOTE

          SECOND AMENDMENT, dated as of April 3, 2000 (this "Second Amendment"),
to the 7.5% Secured Note issued by Bio-Plexus, Inc. (the "Company") to Appaloosa
Investment Limited Partnership I (the "Holder") on October 21, 1999 (as such
Note may be amended and restated from time to time, the "Note")

                            W I T N E S S E T H:

          WHEREAS, the Company has issued the Note to the Holder;

          WHEREAS, the Company and the Holder have entered into a First
Amendment to the Note on December 30, 1999, which provided, among other things,
that the interest on the Note would accrue, beginning on December 30, 1999, at a
rate of 12%;

          WHEREAS, the Company has requested that the Holder further amend
certain provisions of the Note;

          WHEREAS, the Holder is willing to agree to the requested
amendments, but upon the terms and conditions set forth herein;

          NOW, THEREFORE, in consideration of the premises and mutual covenants
contained herein, the Company and the Holder hereby agree as follows:

          1. Defined Terms. Unless otherwise defined herein, capitalized terms
which are defined in the Note are used herein as therein defined.

          2. Amendment to Note.

          (a) Subsection 4.4 of the Note is further amended by deleting the date
at the end of the first clause of the first sentence thereof and substituting in
lieu therefor "April 30, 2000".

          (b) Subsection 5.1(d) of the Note is further amended by deleting all
references therein to "February 28, 2000" and substituting in lieu therefor
"April 30, 2000".

          (c) Subsection 6.4 of the Note is further amended by deleting the
reference to "February 28, 2000" and substituting in lieu therefor "April 30,
2000".

          (d) Subsection 7.1 of the Note is further amended by deleting the
definitions of "15% Secured Note," "Maturity Date," "Proxy Statement" and
"Transaction Documents" in their entirety and substituting in lieu therefor
the following:

               "Maturity Date" shall mean the earlier of April 30, 2000 and the
               Rollover Date.

               "Proxy Statement" shall mean the proxy statement in a definitive
               form relating to the Company Meeting and any amendments,
               supplements or other solicitation materials relating thereto.
<PAGE>   2
               "Second Bridge Loan" means the 15% Secured Note in the initial
               aggregate principal amount of $1,650,000 issued by the Company to
               the Holder on January 5, 2000, as such 15% Secured Note may be
               amended from time to tome.

               "Third Bridge Loan" means the 15% Secured Note, in the initial
               aggregate principal amount of $2,200,000, issued by the Company
               to the Holder on the date hereof, as such 15% Secured Note may be
               amended from time to time.

               "Transaction Documents" shall mean this Note, the Second Bridge
               Loan, the Third Bridge Loan, the side letter, dated December 30,
               1999, between the Company and the Holder (as such side letter may
               be amended and restated from time to time), the Security
               Agreement, the Registration Rights Agreement, the warrants to be
               issued to Affiliates of the Holder pursuant to section (c) of the
               aforesaid side letter, the Warrants and the side letter, dated
               April 3, 2000, between the Company and the Holder (as such side
               letter may be amended and restated from time to time).

          3. Representations and Warranties. The Company hereby confirms,
reaffirms and restates the representations and warranties set forth in Section 3
of the Note. The Company represents and warrants that as of the date hereof and,
after giving effect to this Second Amendment and the transactions contemplated
hereby, no Default or Event of Default has occurred and is continuing.

          4. Effectiveness. The Second Amendment shall become effective as of
the date upon which the Holder receives the counterpart of this Second Amendment
duly executed by the Company and a duly executed copy of the side letter, dated
the date hereof, between the Company and the Holder.

          5. Continuing Effect of the Transaction Documents. This Second
Amendment shall not constitute an amendment of any other provisions of the Note
or any other Transaction Documents not expressly referred to herein and shall
not be construed as a waiver or consent to any further or future action on the
part of the Company that would require a waiver or consent of the Holder. Except
as expressly amended hereby, the provisions of the Note and the other
Transaction Documents are and shall remain in full force and effect.

          6. Counterparts. This Second Amendment may be executed by the parties
hereto in any number of separate counterparts, each of which shall be deemed to
be an original, and all of which taken together shall be deemed to constitute
one and the same instrument.

          7. GOVERNING LAW. THIS SECOND AMENDMENT SHALL BE GOVERNED BY,
AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW
YORK.

<PAGE>   3

          IN WITNESS WHEREOF, the parties hereto have caused this Second
Amendment to be duly executed and delivered by their respective proper and duly
authorized officers as of the day and year first above written.

                                        BIO-PLEXUS, INC.

                                        By: /s/ Carl R. Sahi
                                           --------------------------------
                                           Name:  Carl R. Sahi
                                           Title: President and Chief
                                                  Executive Officer

                                        APPALOOSA INVESTMENT LIMITED
                                          PARTNERSHIP I

                                        By:  Appaloosa Management L.P., its
                                               General Partner
                                        By:  Appaloosa Partners Inc., its
                                               General Partner

                                        By: /s/ James E. Bolin
                                           --------------------------------
                                           Name:   James E. Bolin
                                           Title:  Vice President

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