Surface Plasmon Resonance Sensing and Characterisation of Nano-Colloids for Nanotoxicology Applications

Abstract

In this research, a Surface Plasmon Resonance (SPR) based sensor system was developed for quick detection of not only silver nanoparticles at low concentrations, but also to a range of individual analytes, according to their optical properties. SPR-based sensors are extremely sensitive to changes in the optical properties of the local environment at this interface, making these instruments highly valuable for surface science and bio-sensing experiments. This has enabled silver in solution (silver nitrate) to be detected from colloidal nanoparticles. This study involves the theoretical development of an SPR system, where a glass prism and a multi-layered chip are used. The model presented is rigorous and applicable for any multilayer system. With this model, different parameters of the sensor can be selectively altered allowing the user to optimise the sensor’s response for a particular analyte and to determine system parameters on the basis of results obtained during experiments. Both theoretical predictions and experimental measurements show that the predicted effective permittivity of silver nanoparticles Ag NPs compared with silver nitrate AgNO3 enabled the presence of colloidal silver versus silver in solution to be differentiated down to a concentration limit of 0.1 mgl-1. Different materials were analysed for the compatibility and chemical stability for fabricating biochips. It has been successfully demonstrated that graphene-based SPR sensors are quite promising instruments owing to their improved sensitivity and other beneficial characteristics. Discussion related to different results obtained during experiments is also included together with some recommendations. Opportunities for future research are also mentioned, such as miniaturisation of an SPR sensor system for portable applications so that this technology can be utilised for detection of nano toxicants in the environment.