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Hollow gold nanoparticles encapsulating horseradish peroxidase
Rajiv Kumar1, A N Maitra, P K Patanjali
1Department of Chemistry, University of Delhi, Delhi 110 007, India.
Biomaterials
|June 14, 2005
Summary
Researchers created hollow gold nanoshells encapsulating active horseradish peroxidase (HRP) enzyme. These nanoshells enable enzymatic reactions with small molecules but block larger ones, demonstrating enzyme activity within nanostructures.
Area of Science:
- Nanotechnology
- Biochemistry
- Materials Science
Background:
- Enzyme encapsulation within nanostructures is crucial for biocatalysis and biosensing.
- Developing methods to maintain enzyme activity within synthetic nanomaterials remains a challenge.
Purpose of the Study:
- To prepare hollow gold nanoshells containing active horseradish peroxidase (HRP).
- To investigate the enzyme kinetics and substrate accessibility within these nanoshells.
Main Methods:
- Preparation of Au(shell)AgCl(core) nanoparticles using reverse micelles.
- Leaching of AgCl core with ammonia to create hollow nanoshells.
- Characterization using dynamic laser light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electron diffraction.
Main Results:
- Successfully synthesized hollow gold nanoshells with entrapped HRP, with particle sizes below 100 nm.
- Entrapped HRP retained activity, catalyzing the oxidation of small substrates (o-dianisidine) following Michaelis-Menten kinetics.
- Enzymatic activity was inhibited when the substrate was conjugated with a 10 kDa dextran molecule, suggesting pore size limitations.
Conclusions:
- Soft-chemical synthesis enables the preparation of enzyme-loaded hollow gold nanoshells with preserved enzymatic activity.
- The pore structure of the nanoshells controls substrate accessibility, allowing selective enzymatic reactions.
- Hollow gold nanoparticles offer a promising platform for enzyme immobilization and controlled biocatalysis.