Optical and Electrochemical Biosensors for Detection of Pathogens Using Metal Nanoclusters: A Systematic Review

Abstract

The rapid and accurate detection of pathogenic bacteria and viruses is critical for infectious disease control and public health protection. While conventional methods (e.g., culture, microscopy, serology, and PCR) are widely used, they are often limited by lengthy processing times, high costs, and specialized equipment requirements. In recent years, metal nanocluster (MNC)-based biosensors have emerged as powerful diagnostic platforms due to their unique optical, catalytic, and electrochemical properties. This systematic review comprehensively surveys advancements in MNC-based biosensors for bacterial and viral pathogen detection, focusing on optical (colorimetric and fluorescence) and electrochemical platforms. Three key aspects are emphasized: (1) detection mechanisms, (2) nanocluster types and properties, and (3) applications in clinical diagnostics, environmental monitoring, and food safety. The literature demonstrates that MNC-based biosensors provide high sensitivity, specificity, portability, and cost-efficiency. Moreover, the integration of nanotechnology with biosensing platforms enables real-time and point-of-care diagnostics. This review also discusses the limitations and future directions of the technology, emphasizing the need for enhanced stability, multiplex detection capability, and clinical validation. The findings offer valuable insights for developing next-generation biosensors with improved functionality and broader applicability in microbial diagnostics.

Keywords: bacterial detection; metal nanocluster-based biosensors; microbial infections; nanobiosensors; virus detection.

Figure 2

(I) Diagram showing the working principle of a colorimetric aptasensor for detecting S. typhimurium [103]. (II) Illustration of the detection mechanism using an aptamer-papain-AuNCs sensor [105]. (III) Principle of a Salmonella colorimetric biosensor: (A) biosensor structure composed of C1-C5 chambers, (B) electromagnetic states for fluid control, (C) sensing mechanism [108]. (IV) Illustration of a colorimetric biosensor for S. typhimurium detection in milk, using aptamer-induced multi-DNA release and peroxidase-mimicking DNA-Ag/PtNCs: (A) Illustration of the design of biosensor, (B) Illustration of the detection mechanism [111].

Figure 5

(I) (a) Synthesis and functionalization process of MagAushell NPs for biosensing applications. (b) Structural design and working principle of the LFIA-based biosensor for SARS-CoV-2 detection. (c) Interpretation of test results, including visual and infrared thermal imaging of positive and negative samples [137]. (II) Gold nanocluster-based immunoassay (AuNCIA) for HIV-1 p24 antigen detection [139]. (III) Synthesis of fluorescent DNA-templated silver nanoclusters (DNA-AgNCs) using a three-way branched DNA scaffold for H5N1 detection [142]. (IV) Development of multifunctional silver nanoclusters/graphene oxide (AgNCs/GO) fluorescence platform for label-free DNA detection via hybridization chain reaction (HCR) amplification [144]. (V) Schematic representation of target DNA detection through fluorescence signal amplification triggered by hybridization with a hairpin DNA probe [149]. (VI) Representation of a dual-emission ratiometric DNA-templated silver nanoclusters for label-free COVID-19 detection [93].

Scheme 1

Schematic representation of MNCs applications for photoluminescence, electrochemical, and colorimetric detection of viral and bacterial infections. Created with BioRender.com.

Figure 1

PRISMA flowchart of the search strategy covering the period 2007–2025.

Figure 3

(I) Schematic representation of Listeria monocytogenes detection using LeuA and AuNCs [114]. (II) Schematic representation of (A) single-step synthesis of vancomycin-conjugated gold nanoclusters (AuNCs@Van) and (B) dual-recognition detection strategy for Staphylococcus aureus (SA) in mixed samples using Apt-MB and AuNCs@Van [116]. (III) Visual representation of the FRET-based detection platform for S. aureus employing dual-recognition elements: vancomycin and aptamer [118].

Figure 4

(I) Illustration of the LPS detection mechanism using the PmB/CuNCs/CuF sensing platform [133]. (II) ECL Biosensing Platform for CLas Omp Gene Utilizing RCA Amplification and CRISPR/Cas12a-Activatable DNA Hydrogel: (a) ECL biosensor detection mechanism; (b) DNA hydrogel templated synthesis of AuAg nanoclusters; (c) RCA-mediated target amplification triggering CRISPR/Cas12a activity [134].

Figure 6

(I) Schematic representation of the biosensor fabrication process: (a) initial signal generated by the capture probe; (b) final signal after target DNA incubation with Exo III [160]. (II) Schematic overview of the split-type ECL DNA biosensor using AuNCs for HPV16 E7 detection [161]. (III) Diagram illustrating the working principle of the Cas12a-based ECL biosensor for HPV-16 DNA detection [162].