Abstract

Swellable organically modified sillica (SOMS) is a flexible mesoporous silica that can be used as adsorbent for proteins and small organic molecules. To assess the potential of SOMS as support material for enzyme immobilization for drinking water treatment, immobilized proteins in SOMS were characterized for accessibility to small molecule solutes and activity. SOMS achieve high immobilization capacity to cytochrome c, myoglobin and acid phosphatase by physical adsorption. The adsorption of these proteins were irreversible as tested by desorption in both water and ethanol. The immobilization mechanism was suggested to be physical caging (entrapment) for protein having a Stoke radius from 1.5 nm to 2.5 nm. Small molecules such as ascorbic acid and biotin were able to access and bind to entrapped cytochrome c and immobilized streptavidin respectively in SOMS. The folding state and structure of entrapped cytochrome c and entrapped myoglobin were maintained in SOMS. In addition, SOMS appeared to increase the thermal stability of secondary structure of cytochrome c and myoglobin. Entrapped acid phosphatase and entrapped horseradish peroxidase (HRP) has significantly reduced enzymatic activity in SOMS. The reduction in enzymatic was suggested to be caused by the hindered diffusion of substrate into the pores and adsorption of substrates. SOMS partially improved the enzyme thermal stability of acid phosphatase, possibly because of enzyme aggregation in the pores.

Advisor

Edmiston, Paul

Department

Biochemistry and Molecular Biology

Disciplines

Biochemistry | Materials Chemistry | Structural Biology

Keywords

SOMS, Swellable Organically Modified Silica, enzyme immobilization, immobilized proteins, protein adsorption, thermal denaturation, enzymatic activity, cytochrome c, myoglobin, streptavidin, acid phosphatase

Publication Date

2018

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2018 Duc A. Pham