Role of Capping Agent for the Colorimetric and Fluorescent Sensing of Different Materials Using Metal Nanoparticles

Background: The selection of capping agent depends on the method of synthesis, nature of nanoparticles (NPs), and type of the compounds to be analyzed. Therefore, different types of capping agents such as surfactants, drugs, amino acids, fatty acids, and polymers are used to increase stability of NPs, avoid aggregation, keep NPs away from one another, thereby achieving desired morphology as well as the size of NPs. Introduction: Recently, the fabrication of NPs has been extensively carried out using synthetic chemical routes in a wide range of materials. In this review, a comprehensive assessment of the colorimetric and fluorescent sensing of metal nanoparticles using different capped agents, such as surfactants, drugs, amino acids, fatty acids, and polymers has been summarized for the present and future strategies. Method: For the synthesis of metal nanoparticles, different methods, metals, and a variety of capping agents are used to obtain new properties and explore opportunities for innovative applications. Result: Capping agents perform their significant role as stabilizers to avoid the over-growth and coagulation of nanoparticles. Conclusion: Capping agents play an essential role in the colorimetric and fluorescent sensing of metal nanoparticles for particular analytes.