Apatite formation on active nanostructured coating based on functionalized gold nanoparticles

Abstract

In this work, we developed a simple method of surface functionalization of polymer substrates to provide them with the ability to form biomimetic hydroxyapatite (HA) when incubated in synthetic body fluids (SBF). In a first step, gold nanoparticles (AuNPs) were used as surface nanostructuring units for a biocompatible polymer, poly(2-hydroxyethyl methacrylate), known to not promote biomineralization in SBF, and under physiological conditions. The treatment of AuNPs-modified substrate with mercaptosuccinic acid leads to brushes of carboxyl-ended chains self-assembled onto the gold-polymer hybrid nanosurface. The main aim of this work was to demonstrate that these multianionic nanosurfaces would induce HA formation when incubated in solutions mimicking physiologic conditions. The formation of apatite and its morphology and composition were successfully investigated by means of high resolution scanning and transmission electron microscopy with energy dispersive X-ray microanalysis, infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Emphasis was put on the nucleation of HA in areas with agglomerated carboxyl-ended functionalized nanoparticles. The results obtained in this study may unlock new applications for smart active coatings based on functionalized AuNPs, such as the induction of biomineralization.