On the optical and thermal properties of in situ/ex situ reduced Ag NP’s/PVA composites and its role as a simple SPR-based protein sensor

A Nimrodh Ananth,J Sophia,S Umapathy,T Mathavan,D Mangalaraj

doi:10.1007/s13204-011-0010-7

Abstract

Silver/polyvinyl alcohol (Ag-PVA) nanocomposite films have been prepared via in situ generation of silver nanoparticles (Ag NPs) by the respective metallic salts and dispersion of preformed Ag NPs (ex situ synthesis) inside polyvinyl alcohol (PVA) and its effect of sensing towards a model protein (bovine serum albumin—BSA) was investigated. The influence of Ag NPs, irrespective of their reduction methodology on the optical and the thermal properties of the PVA, had been investigated using UV–Vis spectrophotometer and differential scanning calorimetry. The absorption peak around 400 nm indicates the surface plasmon resonance response of Ag NPs. The interaction of the dispersed and preformed Ag NPs with the PVA chains is confirmed by the corresponding vibrational signatures of the PVA through Fourier transform infrared spectroscopy (FTIR). The changes in the glass transition and melting temperatures (Tg and Tm) of the pure PVA upon the presence of Ag NPs are reported using differential scanning calorimeter (DSC). The sizes of the synthesized Ag NPs are found to be in the range of 200 ± 10 nm for in situ reduction of silver nitrate (AgNO3) and 100 ± 10 nm for the external addition of preformed Ag NPs by sodium borohydride (NaBH4) reduction using scanning electron microscopy (SEM).

Highlights

Metal nanoparticles incorporated polymers attracted great attention because of the widened application scope offered by these hybrid materials (Nesher et al 2008; Wang et al 2002; Clemenson et al 2006; Akamatsu et al 2000; Zeng et al 2002)
The graph ‘a’ in the Fig. 3 corresponds to the ex situ synthesis of silver nanoparticles stabilized with polyvinyl alcohol, whereas the graph ‘b’ corresponds to the in situ generation of silver nanoparticle in PVA
The full width half maximum (FWHM) of the respective absorption patterns of ex situ/in situ generated Ag NPs are found to be 64.30 and 99.13 nm. This reveals that the size distribution of the particles is broader (Ershov et al 1993) for in situ synthesized silver nanoparticles when compared with the addition of preformed nanoparticles

Summary

Introduction

Metal nanoparticles incorporated polymers attracted great attention because of the widened application scope offered by these hybrid materials (Nesher et al 2008; Wang et al 2002; Clemenson et al 2006; Akamatsu et al 2000; Zeng et al 2002). Polymers are considered as good host materials for metal nano colloids by providing a protective coating layer over the highly active particles. Silver nanoparticles protected by polymers such as PVA, PVP, PMMA are extensively reported (Zhou et al 1999; Chou and Ren 2000; Khanna et al 2004; Zhang et al 1996; Monti et al 2004). PVA could be considered as a good host material for metal due to its excellent thermo stability

Objectives

Results

Conclusion