Fluorescent Metal Nanoclusters for Detecting Pathogens

The rapid, accurate, and on-site detection of pathogens has become increasingly vital in a diverse range of sectors such as clinical diagnostics, food safety, and environmental surveillance. Nanomaterials have played a significant role in advancing sensor performance. Among them, metallic nanoclusters (NCs)—composed of a few to several hundred metal atoms—have emerged as a promising class of fluorescent nanoprobes due to their size-dependent fluorescence, excellent photostability, large Stokes shifts, and tunable surface chemistry. In addition, certain nanoclusters demonstrate peroxidase-like catalytic activity, enabling their use as nanozymes in colorimetric sensing platforms. These properties make NCs highly attractive for bioanalytical applications, particularly for the detection of various analytes including pathogens relevant to biomedical, food safety, and environmental monitoring contexts. Given the critical importance of pathogen detection and the advantageous properties of nanoclusters in sensing technologies, this chapter provides a comprehensive overview of fluorescent metallic nanoclusters and their applications in pathogen detection. Emphasis is placed on both monometallic and bimetallic nanoclusters, as well as their combinations with other nanostructures such as metal–organic frameworks (MOFs). Various synthesis methods and functionalization strategies developed to enhance their optical and biological performance are systematically reviewed. The chapter further examines primary sensing mechanisms employed in NC-based biosensors, including fluorescence enhancement and quenching, Förster resonance energy transfer (FRET), aggregation-induced emission (AIE), and enzyme-mediated colorimetric detection. Additionally, future perspectives on the place of nanoclusters in the generation of pathogen detection approaches will be discussed.