271436 Layer-by-Layer Assemblies for Membrane-Based Enzymatic Catalysis
Abstract: Biomolecule immobilization within the porous domain of microfiltration membrane media is a classic, well- studied approach for applications in such areas as enzymatic catalysis and separations. While considerable progress has been made in regards to understanding the optimal conditions for the preservation of the activity of these immobilized biomolecules, much more work is required in order to fully quantify these precise conditions for each type of biomolecule. An effective approach to biomolecule immobilization is layer-by-layer (LbL) functionalization, which holds promise due to the electrostatic nature of these assemblies. Since, in nature, enzymes and proteins exist in an electrostatic environment, the layer-by-layer approach offers a relatively high magnitude of immobilized biomolecular activity, as opposed to other methods of immobilization such as covalent attachment.
The goal of this study is to define and quantify the optimal electrostatic environments for enzymatic immobilization in order to maximize enzyme activity and overall membrane reaction effectiveness. Glucose oxidase (GOx) was used as a model enzyme within a poly(acrylic acid) (PAA)-poly(allylamine hydrochloride) (PAH)-functionalized poly(vinylidene fluoride) (PVDF) microfiltration membrane pores. The local activities of enzymes need to be quantified as a function of the properties of positively and negatively charged functional species within the porous domain, surface charge, enzyme immobilization configuration, and bulk membrane properties. The study is mainly focused on the analyses of these data, particularly the comparison of functionalized surface chemistry with local enzymatic configuration and activity. The understanding of the effect of these surfaces and enzyme locations will be important for advancing the LbL methods. Enzyme activities are quantified using batch experiments under convective modes through pressure modulations.