Spectroscopy-based study on the interaction between gold nanoparticle and poly(vinylpyrrolidone) molecules in a non-hydrocolloid

Manoranjan Behera,Shanker Ram

doi:10.1186/2228-5326-3-17

Manoranjan Behera, Shanker Ram

Open Access

https://doi.org/10.1186/2228-5326-3-17

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Abstract

The study of the interaction between poly(vinylpyrrolidone) (PVP) and gold (Au) nanoparticles (NPs) in a colloid is of special interest for possible applications in the field of catalysis, biosensing, and biomedicine. A strong optical absorption arising from Au NPs at 532 nm in Au-PVP colloids is ascribed to surface plasmon resonance. The X-ray photoelectron spectroscopic results confirm reduction of the Au3+ ion to Au0. A noticeable decrease in the binding energies of the Au4f doublet peak of the Au NP with PVP as compared to the bulk Au atom implies interfacial interaction between the Au NP and PVP molecules. A marked enhancement in vibrational band intensities of C-H (2,961, 2,936, and 2,872 cm−1) stretching, C-N (1,463 cm−1) stretching, and CH2 (1,381 cm−1) bending vibrations in the pyrrolidone ring of PVP molecules reveals a charge-transfer-type interaction between the PVP molecules and surface of the Au NP. A significant decay of the emission band intensity (approximately 85%) in the π ← π* band of the PVP molecules at approximately 392 nm in the presence of Au NPs suggests non-bonding (n) electron transfer from the O atom of the pyrrolidone ring of PVP molecules to the electron-deficient Au NP. A negative zeta potential of (−) 15.2 mV reveals accumulation of n-electrons of the O atom of the carbonyl group of PVP molecules on the surface of the Au NP. Transmission electron microscopic images of PVP-capped Au NPs corroborate the spectroscopic results.

Highlights

The study of the interaction between poly(vinylpyrrolidone) (PVP) and gold (Au) nanoparticles (NPs) in a colloid is of special interest for possible applications in the field of catalysis, biosensing, and biomedicine
In the presence of PVP, the blueshift in the typical surface plasmon resonance (SPR) band to 532 nm (as shown in Figure 1 (c)) is ascribed to the quantum confinement effect [3,13]. Such effect arises when Au NPs are covered with a thin film of a dielectric material such as polymeric layer which helps in congregating n-electrons of PVP on the Au surface [13,22,40]
Such a large molar extinction coefficient is observed when PVP gets adsorbed on the surface of the NP and helps in altering the electronic properties of Au NPs by accumulating n-electrons of C=O moiety of PVP molecules on the Au surface in the Au-PVP nanocomposite [13,22,40]

Summary

Introduction

The study of the interaction between poly(vinylpyrrolidone) (PVP) and gold (Au) nanoparticles (NPs) in a colloid is of special interest for possible applications in the field of catalysis, biosensing, and biomedicine. A marked enhancement in vibrational band intensities of C-H (2,961, 2,936, and 2,872 cm−1) stretching, C-N (1,463 cm−1) stretching, and CH2 (1,381 cm−1) bending vibrations in the pyrrolidone ring of PVP molecules reveals a charge-transfer-type interaction between the PVP molecules and surface of the Au NP. A significant decay of the emission band intensity (approximately 85%) in the π ← π* band of the PVP molecules at approximately 392 nm in the presence of Au NPs suggests non-bonding (n) electron transfer from the O atom of the pyrrolidone ring of PVP molecules to the electron-deficient Au NP. A negative zeta potential of (−) 15.2 mV reveals accumulation of n-electrons of the O atom of the carbonyl group of PVP molecules on the surface of the Au NP. Transmission electron microscopic images of PVP-capped Au NPs corroborate the spectroscopic results

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Conclusion