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Biomembrane-Compatible Sol-Gel-Derived Photocatalytic Titanium Dioxide
Tristan J. Johnson1, Sukriti Gakhar1, Yue Deng1
1Department of Chemical Engineering and ‡Department of Materials Science and Engineering, University of California Davis , Davis, California 95616, United States.
ACS Applied Materials & Interfaces
|September 27, 2017
Summary
Titanium dioxide gels successfully encapsulated bacteriorhodopsin, a proton pump, maintaining its function. This biocompatible bionanocomposite shows potential for visible light photocatalysis and hydrogen production.
Area of Science:
- Materials Science
- Biotechnology
- Photocatalysis
Background:
- Titanium dioxide (TiO2) is a widely used photocatalyst.
- Encapsulating biomolecules in TiO2 matrices is challenging due to potential denaturation.
- Bacteriorhodopsin is a light-activated proton pump with potential applications in energy conversion.
Purpose of the Study:
- To synthesize titanium dioxide gel monoliths capable of encapsulating bacteriorhodopsin.
- To assess the biocompatibility of the TiO2 matrix for the membrane protein.
- To evaluate the photocatalytic activity of the resulting bionanocomposite.
Main Methods:
- Sol-gel synthesis of TiO2 gel monoliths using varying ethanol concentrations (0-30 vol%).
- Encapsulation of bacteriorhodopsin in its native purple membrane form within the TiO2 gels.
- Characterization using absorption spectroscopy to confirm protein integrity and function.
- Assessment of photocatalytic activity under UV and visible light irradiation.
Main Results:
- Bacteriorhodopsin remained folded and functional in TiO2 gels synthesized with 0 and 15 vol% ethanol.
- The protein retained reversible conformational changes associated with its photocycle in gels with 0 vol% ethanol.
- TiO2 gels exhibited significant photocatalytic activity, comparable to commercial nanoparticles.
- Biocompatibility was achieved by minimizing ethanol and maximizing water in the synthesis.
Conclusions:
- Sol-gel derived titanium dioxide can be made biocompatible for membrane proteins like bacteriorhodopsin.
- The developed bionanocomposite is a promising platform for visible light photocatalysis.
- This work represents a first step towards utilizing bacteriorhodopsin-TiO2 composites for applications such as hydrogen production.
