(524d) "Living/Controlled" Molecular Imprinting Polymerization Techniques to Enhance Drug Delivery Networks | AIChE

(524d) "Living/Controlled" Molecular Imprinting Polymerization Techniques to Enhance Drug Delivery Networks

Authors 

Vaughan, A. D. - Presenter, Auburn University


Enhanced drug loading and extended release in hydrogels can be achieved by molecular imprinting techniques, which involve the formation of a pre-polymerization complex between the template therapeutic and functional monomers by non-covalent chemistry. In this work, thin polymer films have been synthesized via templated mediated polymerization resulting in macromolecular recognition or ?trained? recognition for diclofenac sodium, a non-steroidal anti-inflammatory drug, within the resulting network. Creating molecular memory within polymer chains can significantly delay release and is a novel, generalizable way to further control and extend release and increase loading in addition to current techniques. Also, ?living/controlled? polymerizations techniques have been used in the creation of these polymer gels and significantly enhanced template loading and delayed transport. Diclofenac sodium imprinted poly(diethylaminoethyl methacrylate-co-2-hydroxyethyl-methacrylate-co-polyethylene glycol200dimethacrlyate) (poly(DEAEM-co-HEMA-co-PEG200DMA)gels synthesized via ?living/controlled? methods show a two-fold increase in the duration of release compared to diclofenac sodium imprinted gels synthesized via standard free-radical polymerization techniques and a four-fold increase in the duration of release compared to the non-imprinted control gel. Also, diclofenac sodium loading capacities increased two-fold from (1.87 ± 0.30 to 3.54 ± 0.25) x 10-2 mmole/g while retaining similar template binding affinities when comparing conventional free-radical polymerization to living polymerization. Structural analysis of the imprinted gels also demonstrated that ?living/controlled? polymerization techniques decreased the average mesh size from 30.3 ± 1.7 to 19.7 ± 2.1 A. This directly correlated with the enhanced loading and delayed release of the imprinted structure and is the first time living polymerization strategies have been shown to lead to more effective binding cavities within a flexible hydrogel network. The release profiles from imprinted gels demonstrated less Fickian behavior and moved closer toward a zero-order release profile with both ?living/controlled? and standard free-radical imprinting polymerization techniques. Utilization of ?living? polymerization techniques within the synthesis of loosely crosslinked polymers thin films augment the tailorability of the release profiles and enhance the resulting loading capacity which significantly improves the potential of hydrogel drug delivery carriers. Characterization analysis of the network structure of the hydrogel carrier in terms of molecular weight between crosslinking points, mesh size, and diffusion studies provides an aid to optimizing the design and begins to answer fundamental questions on the nature of the recognition and extended delivery in imprinted hydrogels on the chain level.