Bio-Fabricated Gold and Silver Nanoparticle Based Plasmonic Sensors for Detection of Environmental Pollutants: An Overview

Water resources of our earth is currently facing a serious challenge due to human activities including industrial development, agricultural revolution, urban growth and deforestation. The first step for pollutant removal is obviously their detection in water which requires use of various well known instrumentation techniques or use of sensors. Of all the different types of sensors, gold and silver nanoparticle based colorimetric/plasmonic nano-sensors are particularly noteworthy because of their simplicity and low cost. These nano-sensors are based on principle of SPR, an optical phenomenon immensely dependent on characteristics of the nanoparticles. Noble metal nanoparticles are widely chosen for colorimetric sensing application as their SPR absorbance lie in the visible region of spectrum rendering unique colors to them. Also, they are easy to synthesize, easy to functionalize, biocompatible and stable. In this detection technique, the presence of a pollutant is revealed by a distinct, visual color change and can also be quantified using a UV-Visible Spectrophotometer. Sustainable chemistry being one of the focal points of modern chemistry research, green synthesis of nanoparticles, particularly noble metal nanoparticles such as gold and silver have attracted considerable attention in last decade. Although gold and silver nanoparticles based optical sensor have been summarized in various reviews over last few years, colorimetric nano-sensors synthesized by green methods have found little discussion in scientific literature. This critical review aims to connect this gap by portraying this sparsely explored area of application of biosynthesized silver and gold nanoparticles and thus will assist the researchers working in this field.

Automated summary

The water resources of our planet are under significant pressure due to human activities such as industry, agriculture, urbanization, and deforestation. Detecting pollutants in water is the first step in their removal, and this requires the use of various instrumentation techniques or sensors. Among the different types of sensors, gold and silver nanoparticle-based colorimetric/plasmonic nano-sensors are particularly significant due to their simplicity and low cost. These sensors are based on the principle of surface plasmon resonance (SPR), which is an optical phenomenon dependent on the characteristics of nanoparticles. Noble metal nanoparticles, such as gold and silver, are widely used in colorimetric sensing applications because their SPR absorbance lies in the visible spectrum, resulting in unique colors. They are also easy to synthesize, functionalize, biocompatible, and stable. In this detection technique, the presence of a pollutant is revealed by a distinct visual color change and can be quantified using a UV-Visible Spectrophotometer. The review aims to address the gap in scientific literature by exploring the application of green-synthesized silver and gold nanoparticles in colorimetric nano-sensors, thereby assisting researchers in this field.