The Effect of Silver Nanoparticles on the Collagen Secondary Structure

Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR) spectroscopy is a label-free, non-destructive analytical technique that can be used extensively to study a wide variety of molecules in different conditions. Proteins have very complicated three dimensional structures with multi-level conformations, which are highly correlated with their biological activities. Recently, there is a significant increase of materials based on interaction between proteins and nanoparticles. The aim of this paper is to highlight the understanding of protein interaction with silver nanoparticles (AgNPs) surfaces. Information about the secondary structures of collagen with and without AgNPs was obtained from atomic force microscopy (AFM) measurements.ATR-FTIR spectroscopy was used for monitoring the changes in the secondary structures of collagen upon interaction with AgNPs. Amide I is the most sensitive band for detecting changes in the protein secondary structures. Its characteristic absorption band is located at 1600–1700 cm-1. Comparing the spectra of collagen with and without AgNPs in this region, information about the different types of secondary structures such as α-helix, β-sheets, turns and random coil can be obtained. The conjugation of AgNPs-collagen occurred mainly through electrostatic interactions. Based on these data, the effects of AgNPs stability and the conformational changes of collagen upon interaction with the AgNPs are discussed.