<PAGE>

                                                                   EXHIBIT 10.10

                                 PROMISSORY NOTE

$400,000.00                                                       AUGUST 7, 2000
                                                             LITTLETON, COLORADO

        For consideration received, AspenBio, Inc., a Colorado corporation
("Maker") promises to pay to the order of Roger D. Hurst ("Holder") in
accordance with the provisions set forth below, the principal sum of FOUR
HUNDRED THOUSAND DOLLARS ($400,000.00), together with interest thereon,
compounded on the first of each month commencing on August 1, 2000, at the rate
of eight percent (8%) per annum.

        Maker shall make one payment of Two Hundred and Sixty Thousand Dollars
($260,000.00) of principal on January 1, 2002. Maker shall make quarterly
payments consisting of principal and interest on the first day of each calendar
quarter, commencing with April 1, 2002 until there is no principal or interest
outstanding and in accordance with the payment schedule attached hereto as
Exhibit A. All amounts due pursuant to this Note shall be paid in cash or other
immediately available funds to Holder in care of Maker at 8100 Southpark Way,
Unit B-1, Littleton, Colorado 80120, or at such other address as may have been
fixed by reasonable notice to Maker. Maker may prepay the principal amount
outstanding in whole or in part at any time without penalty or premium. Any
partial prepayment shall not postpone the due date of any subsequent installment
unless the Holder shall otherwise agree in writing.

        The loan represented by this Note is solely for commercial and business
purposes, and is not made in connection with a consumer transaction. The loan
represented by this Note is not for personal, family, agricultural or household
purposes. The loan represented by this Note is not a consumer loan within the
meaning of the Uniform Consumer Credit Code ("UCCC") and accordingly the UCCC
shall not apply to this Note.

        This Note shall be in default if Maker fails to cure, within twenty (20)
days of receipt of written notice from Holder of default, its failure to make
payment of principal or interest due under this Note when the same becomes due
and payable. From and after the date of any such default, all principal and
interest then due hereunder shall thereafter accrue interest at the rate of
twelve percent (12%) per annum. If default shall occur and be continuing and
Holder proceeds to enforce or pursue any legal or equitable remedies, Maker
agrees to pay all expenses incurred by Holder (including reasonable attorneys'
fees) incident to the enforcement of this Note.

        This Note and the obligations hereunder may not be assigned or
transferred to any person or party by Holder without the prior written consent
of Maker, which may be withheld in the sole and absolute discretion of Maker.
Maker may assign or transfer its rights and obligations to any person or party
at any time; provided, that any successor party shall have all rights and
obligations of Maker hereunder. The parties hereto, including Maker and any
guarantors, endorsers, successors, and assigns hereby waive demand, presentment,
protest and notice of protest, diligence, and all other demands and notices in
connection with the delivery, acceptance, performance and enforcement of this
Note, and Maker agrees that Holder may extend the terms for payment or accept
partial payment without discharging or releasing Maker from any of its
obligations hereunder. This Note and its validity, construction, and performance
shall be governed in all respects by the laws of the state of Colorado.

        IN WITNESS WHEREOF, Maker has caused this Note to be duly executed and
dated the day and year first above written.

                                            ASPENBIO, INC.
                                            a Colorado corporation



                                            By:
                                               ---------------------------------
                                                 Roger D. Hurst, President
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                      AMENDED AND RESTATED PROMISSORY NOTE

$267,501.00                                                        APRIL 1, 2002
                                                             LITTLETON, COLORADO

         For consideration received, AspenBio, Inc., a Colorado corporation
("Maker") promises to pay to the order of Roger D. Hurst ("Holder") in
accordance with the provisions set forth below, the principal sum of TWO HUNDRED
AND SIXTY SEVEN THOUSAND FIVE HUNDRED AND ONE DOLLARS ($267,501.00), together
with interest thereon at the rate of eight percent (8%) per annum. This Amended
and Restated Promissory Note (the "Note") amends and restates that certain
Promissory Note in the original principal amount of Four Hundred Thousand
Dollars ($400,000.00) dated August 7, 2000 made by Maker in favor of Holder.

         Maker shall make one payment of Thirty Thousand Dollars ($30,000.00) of
principal on April 30, 2002. Maker shall make a payment of principal and
interest of $50,000 on April 30, 2003 and on April 30, 2004. On April 30, 2005,
Maker shall make a final payment of all principal and interest outstanding under
the Note. All amounts due pursuant to this Note shall be paid in cash or other
immediately available funds to Holder in care of Maker at 8100 Southpark Way,
Unit B-1, Littleton, Colorado 80120, or at such other address as may have been
fixed by reasonable notice to Maker. Maker may prepay the principal amount
outstanding in whole or in part at any time without penalty or premium. Any
partial prepayment shall not postpone the due date of any subsequent installment
unless the Holder shall otherwise agree in writing.

         The loan represented by this Note is solely for commercial and business
purposes, and is not made in connection with a consumer transaction. The loan
represented by this Note is not for personal, family, agricultural or household
purposes. The loan represented by this Note is not a consumer loan within the
meaning of the Uniform Consumer Credit Code ("UCCC") and accordingly the UCCC
shall not apply to this Note.

         This Note shall be in default if Maker fails to cure, within twenty
(20) days of receipt of written notice from Holder of default, its failure to
make payment of principal or interest due under this Note when the same becomes
due and payable. From and after the date of any such default, all principal and
interest then due hereunder shall thereafter accrue interest at the rate of
twelve percent (12%) per annum. If default shall occur and be continuing and
Holder proceeds to enforce or pursue any legal or equitable remedies, Maker
agrees to pay all expenses incurred by Holder (including reasonable attorneys'
fees) incident to the enforcement of this Note.

         This Note and the obligations hereunder may not be assigned or
transferred to any person or party by Holder without the prior written consent
of Maker, which may be withheld in the sole and absolute discretion of Maker.
Maker may assign or transfer its rights and obligations to any person or party
at any time; provided, that any successor party shall have all rights and
obligations of Maker hereunder. The parties hereto, including Maker and any
guarantors, endorsers, successors, and assigns hereby waive demand, presentment,
protest and notice of protest, diligence, and all other demands and notices in
connection with the delivery, acceptance, performance and enforcement of this
Note, and Maker agrees that Holder may extend the terms for payment or accept
partial payment without discharging or releasing Maker from any of its
obligations hereunder. This Note and its validity, construction, and performance
shall be governed in all respects by the laws of the state of Colorado.

         IN WITNESS WHEREOF, Maker has caused this Note to be duly executed and
dated the day and year first above written.

                                        ASPENBIO, INC.
                                        a Colorado corporation



                                        By:
                                           ---------------------------
                                           Roger D. Hurst, President