Recent Developments in Detection Using Noble Metal Nanoparticles

Noble metal nanoparticles (NPs), especially AgNPs and AuNPs, with unique properties, such as ease of operation, economical production, sensitivity, and simplicity of construction, have been widely used as biosensors due to the sensitivity and selectivity of this detection method. However, the efficiency of the NPs used for detection is highly related to the methods and conditions for synthesis and modulation of NPs because their properties are shape- and size-dependent. The mechanisms for sensors that use NPs are mainly dependent on their unique properties in colorimetric, fluorescent, and electrochemical characteristics. The presence of analyte would cause a change of current, potential, capacitance, electrochemical impedance, color, or fluorescence properties of NPs sensors, which provides a specific detection approach by changing the analyte concentration. To achieve an overall understanding of the currently reported studies of NPs used in detecting sensors, this review summarized all previously reported results in this field. AgNPs and AuNPs sensors were also discussed in their applications in food, environmental, and biological fields. Challenges and future opportunities were finally summarized.