Encapsulated Hydrogels by E-beam Lithography and Their Use in Enzyme Cascade Reactions


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Mancini R. J. , Paluck S. J. , BAT E., Maynard H. D.

LANGMUIR, vol.32, no.16, pp.4043-4051, 2016 (Peer-Reviewed Journal) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 32 Issue: 16
  • Publication Date: 2016
  • Doi Number: 10.1021/acs.langmuir.6b00560
  • Journal Name: LANGMUIR
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.4043-4051

Abstract

Electron beam (e-beam) lithography was employed to prepare one protein immobilized hydrogel encapsulated inside another by first fabricating protein-reactive hydrogels of orthogonal reactivity and subsequently conjugating the biomolecules. Exposure of thin films of eight arm star poly(ethylene glycol) (PEG) functionalized with biotin (Biotin PEG), alkyne (Alkyne-PEG) or aminooxy (AO-PEG) end groups to e-beam radiation resulted in cross-linked hydrogels with the respective functionality. It was determined via confocal microscopy that a nominal size exclusion effect exists for streptavidin immobilized on Biotin-PEG hydrogels of feature sizes ranging from 5 to 40 mu m. AO-PEG was subsequently patterned as an encapsulated core inside a contiguous outer shell of Biotin-PEG. Similarly, Alkyne-PEG was patterned as a core inside an AO-PEG shell. The hydrogel reactive end-groups were conjugated to dyes or proteins of complementary reactivity, and the three-dimensional (3-D) spatial orientation was determined for both configurations using confocal microscopy. The enzyme glucose oxidase (GOX) was immobilized in the core of the, encapsulated Alkyne-PEG core/AO-PEG shell architecture, and horseradish peroxidase (HRP) was conjugated to the shell periphery. Bioactivity for the HRP-GOX enzyme pair was observed in this encapsulated configuration by demonstrating that the enzyme pair was capable of enzyme cascade reactions.