Development of novel bioelectrocatalytic platform based on in situ generated gold nanoparticles for biomedical applicati
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Development of novel bioelectrocatalytic platform based on in situ generated gold nanoparticles for biomedical applications Prem C. Pandey and Dheeraj S. Chauhan Department of Applied Chemistry, Institute of Technology, Banaras Hindu University, Varanasi221005, India. ABSTRACT Gold nanoparticles (AuNp) formed using alkoxysilane precursors are utilized in the development of thin organically modified silicates (ormosil) films. The resulting films are optically transparent thereby retaining the optical properties of AuNp. Surface morphology shows that the in situ generated AuNp retained their nanogeometry in the ormosil films. An application of the AuNp encapsulated ormosils is shown in electrocatalytic determination of hydrogen peroxide. For this purpose, potassium ferricyanide is chosen as electron transfer mediator and is encapsulated in the films. Results show that the presence of AuNp in the ormosil matrix dramatically improves the electrochemical behavior of potassium ferricyanide. The ormosil films are utilized for electrocatalytic determination of hydrogen peroxide. In order to investigate the biocompatibility of the ormosil film, horseradish peroxidase (HRP) is incorporated resulting in improvement in oxidation and reduction of peroxide. INTRODUCTION Nanoparticles of noble metals are of immense interest due to their size dependent chemical and physical properties [1-6]. These materials are promising for practical applications and interesting from the scientific point of view, because the gradual evolution of material properties from molecular level to the solid state can be probed by a change of single parameter. Among noble metal nanoparticles, gold nanoparticles (AuNp) are especially attracting much attention owing to their unique catalytic, electronic and optical properties that find wide ranging applications in electrocatalysis and sensor fabrication [7,8]. A number of applications of AuNp require the dispersion of these nanostructures in solid state matrices, while avoiding or controlling aggregation phenomena. In this context, the excellent mechanical, dielectric and chemical properties of silicate networks [7,8] make them a promising choice for the development of advanced materials. The transparent encapsulating matrix only slightly affects the optical properties of the nanocrystalline dispersant. For catalytic and electrocatalytic purposes, fast mass exchange with the surroundings can still be maintained through the porous support. However, even the sol-gel matrices, despite these advantages, present several drawbacks. The limitations of these matrices are poor shape and size tuning of nanoparticles and limited control on concentration of nanoparticles. Additionally, the stabilization of nanoparticles in these matrices is not a trivial matter and often aggregates of nanoparticles are formed. Hence, development of new techniques to allow the dispersion of preformed nanoparticles is highly desirable. Recently, we have put forward a novel protocol for alkoxysilane mediated reduction of noble metal salts l
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