(112d) Tunable Biomolecular Recognition Films for Sensing

Noss, K. R. - Presenter, Department of Chemical Engineering, Auburn University

Synthetic intelligent polymeric materials that can recognize biomolecules have a tremendous potential in micro/nano scale applications such as sensors, biomolecular valves, actuators and point of care diagnostics. Non-covalent complexation between template or ?guest' biomolecules and functional monomers during polymerization can create networks with selective binding sites. The concept of macromolecular recognition manifests itself from two major synergistic effects, (i) shape specific cavities that match the template biomolecule, which provide stabilization of the chemistry in a crosslinked matrix, and (ii) chemical groups oriented to form multiple complexation points with the template. Highly crosslinking imprinted polymers are extremely stable in a wide range of temperatures and pHs making them great candidates for incorporation onto sensor based platforms, such as surface plasmon resonance (SPR), microcantilevers, or quartz crystal microbalances to function as a biomolecular sensor. However, in order to maximize sensor affinity, selectivity and response time, analysis of parameters such as the crosslinking density of the network, template diffusion coefficient, functional monomer to template ratio, and polymerization reaction and kinetics from the bulk material are needed. This work illustrates the use of acrylate and methacrylate copolymer networks with a biocompatible crosslinking agent poly (ethylene glycol-n-dimethacrylate) (n= 1, 4.5) with imprinting template molecules such as testosterone and progesterone. Parameters such as the crosslinking percentage in the feed, the length of the crosslinking monomer, functional monomer to template ratio, polymerization reaction and kinetics, double bond conversion and the reaction rate versus time were analyzed to optimize the binding characteristics of the network for sensing applications. The crosslinker structure and crosslinking percentage of a testosterone recognitive gel was varied from 30%-90% and experienced a tunable increase of affinity ranging from 0.3 x 104 M-1 to 7.1 x 104 M-1. The moles of initiator over the moles of double bonds in the monomer solution and the solvent weight percent were held constant for both poly (ethylene glycol-n-dimethacrylate) (n= 1, 4.5) resulting in the shorter crosslinking agent having a double bond conversion around 40% while the longer crosslinking agent around 55% indicating that the macromolecular structure doesn't accurately represent the feed crosslinking composition. Selectivity studies also show that at a crosslinking percentage of 77%, the testosterone recognitive polymer had a higher affinity for testosterone (5.3 x 104 M-1) than that of progesterone (1.1x104 M-1).