Nanomaterials of metal and metal oxides for optical biosensing application

The advancement of nanotechnology leads to the development of different areas including sensing of various analytes. The high surface area, sensitivity, selectivity, stability, and unique properties of nanomaterials particularly metal and metal oxide-based nanoparticles and their thin film are widely used for sensing applications. The optical properties of metal and metal oxides depend on several factors such as shape, size, surface area, doping, and interaction with the surroundings. Biosensors are various types such as electrochemical, mass-based, biological element-based, and optical. Optical sensor is a facile, rapid, and low-cost technique for the detection of a wide range of compounds such as drugs, toxin, pesticide, chemicals, explosive, environmental motoring, and heavy metals. Optical biosensors are mainly three categories based on optical properties such as fluorescence, surface plasma resonance, and surface-enhanced Raman scattering (SERS) based optical biosensors. Currently, metal-based and metal oxide-based optical sensors are successfully used in various fields due to its noninvasive and extremely sensitive way for label-free detection of a varied range of analytes. Moreover, flexible SERS and fluorescence sensing techniques have attracted huge research attention due to their unique properties and advantages. They offer numerous advantages over other optical sensing techniques in terms of simplicity, selectivity, sensitivity, and low detection limit. This chapter focuses on the development of metal-based and metal oxide-based optical biosensing techniques particularly based on fluorescence, surface plasma resonance, and surface-enhanced Raman spectroscopy and their various advanced applications.