Drug Delivery Technology

M IMETIC
DELIVERY SYSTEMS

unique way to the presence of the analyte to
which it has been imprinted. It does not
simply bind and sequester the analyte, but
the polymer itself swells and can be made
to rupture due to the presence of the
analyte. This creates a system that not only
recognizes, but recognizes and releases.
This system gives the flexibility to
provide release upon not one, but many
different possible triggers. For example, one
of these intelligently designed systems is
currently being used to selectively
recognize and respond to variations in
analyte concentrations and trigger a
controlled, dose-appropriate, level of active
determined by this recognition event.
Therefore, the primary advantage of this
system is that potential Affinimer
technology components can be evaluated
against numerous analytes and
environmental triggers to determine which
combination of analyte and Affinimer
system components will have the most
desirable protection and release
characteristics. It is our belief that this
range of triggering opportunities will allow
utilization of this technology to enhance
release performance in a number of
products and applications.
Utilization of environmentally relevant
analytes, biomarkers, and conditions (ie, the
use of a specific molecule or environmental
trigger) will allow for selective activated
release only at the desired point of use or
application. Furthermore, this approach,
coupled with the use of a robust intelligent
material, will provide the necessary level of
protection of active during storage and
controlled rate of release upon activation.
These systems allow reversible or non-
reversible release, depending on the design
of the system, of incorporated active
agents. The release will happen selectively
due to the presence of the imprinted active
agent and can be made to be proportional
to the amount of agent present or can be an
“all-or-nothing” release when the
concentration of the active agent reaches a
desired or critical amount. Again, these
different formulation types can be prepared
32

Drug Delivery Technology June 2009 Vol 9 No 6

FIGURE 1

Preparation of molecularly imprinted polymers.

using the same basic imprinted polymer structure, then utilizing a variety of controlled-release designs and techniques to give reversible, non-reversible, proportional or complete release of the desired agent. The results that will be presented in this paper confirmed the sensitivity and selectivity of the triggering mechanism as well as quantitative and qualitative release profiles with dose-response curves.

MATERIALS & METHODS

Affinimer films are based on copolymers of methacrylic acid (MAA) cross-linked with triethyleneglycol dimethacrylate (TEGDMA). We have evaluated a number of different monomers as well as cross-linking agents and the combination described here has proven to yield the best balance of imprinted sensitivity,