Stabilisation of (3-mercaptopropyl)-trimethoxysilanecapped ZnS nanocrystals in polyacrylamide hydrogel

Abstract

In this study, we synthesised ZnS nanocrystals and embedded them in polyacrylamide (PAAm) hydrogel to stabilise the fluorescence emission for biomedical applications. ZnS nanoparticles have strong emission but they lose it in time, so generally they are capped with polymers. We capped ZnS nanoparticles with (3–mercaptopropyl)–trimethoxysilane (MPS) and then dispersed them through the PAAm hydrogel. The average size of nanoparticles was found 4.06 nm, but the particles got larger (around ∼16 nm) when they were placed in the gel. FT–IR results show that PAAm strands changed the surface of MPS–capped ZnS during the PAAm polymerisation. Fluorescence studies show that ZnS nanoparticles keep their emission after 3 months, when they are stored in the gel. This feature makes the ZnS nanoparticles suitable as a long–term stable and non–toxic material for medical application.