Luminescent Cu nanoclusters–encapsulated ZIF-8 as on–off–on fluorescent probe for efficient and selective quantification of E. coli

• Published in: Mikrochimica acta (1966) 2025-02, Vol.192 (2), p.56, Article 56
• Main Authors: Kumari, Sonam, Nehra, Monika, Jain, Shikha, Sheokand, Annu, Dilbaghi, Neeraj, Chaudhary, Ganga Ram, Kim, Ki-Hyun, Kumar, Sandeep
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Benzoquinone; Benzoquinones - chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Copper; Copper - chemistry; E coli; Encapsulation; Energy transfer; Escherichia coli - chemistry; Escherichia coli - isolation & purification; Fluorescence Resonance Energy Transfer - methods; Fluorescent Dyes - chemistry; Fluorescent indicators; Hydroquinone; Hydroquinones - chemistry; Limit of Detection; Luminescence; Manganese Compounds - chemistry; Manganese dioxide; Metal Nanoparticles - chemistry; Metal-organic frameworks; Metal-Organic Frameworks - chemistry; Microengineering; Nanochemistry; Nanoclusters; Nanosensors; Nanospheres; Nanotechnology; Nicotinamide adenine dinucleotide; Optical properties; Oxides - chemistry; Public health; Quinones; Reductases; Water quality; Water sampling
• ISSN: 0026-3672; 1436-5073; 1436-5073
• DOI: 10.1007/s00604-024-06905-0

Rapid and accurate detection of Escherichia coli ( E. coli ) is critical for maintaining water quality, and protecting aquatic ecosystems and public health. This research focuses on the development of a Förster resonance energy transfer (FRET)–based “turn-on” fluorescent nanosensor for real time, sensitive detection of E. coli . Copper nanoclusters–encapsulated metal organic frameworks (CuNCs@ZIF-8) were sythesized as a fluorescent donor with excellent luminescence properties. Further, MnO 2 nanospheres were synthesized as a receptor with good adsorption and quenching abilities. This novel nanoconjugate (CuNCs@ZIF-8@ MnO 2 ) was employed for the construction of a sensitive, accurate, and rapid sensing platform against E. coli in water on the basis of p-benzoquinone/hydroquinone (p-BQ/HQ) redox pair formation. Fluorescence is quenched by energy transfer when MnO 2 nanospheres are added to CuNCs@ZIF-8. Upon contact with E. coli , NADH-quinone reductase converts p-BQ to HQ, which reduces MnO 2 to Mn 2+ , releasing the nanospheres and restoring fluorescence in the composite. Based on this FRET ON–OFF-ON fluorescent probe, E. coli can be detected across a broad concentration range (5 × 10 1 to 5 × 10 5  CFU/mL), with a detection limit as low as 8 CFU/mL within 50 min. The sensor’s practicality was verified through the investigation of E. coli in real water samples, with recoveries in the range 94.3 to 106.5%. This approach offers an efficient method for on-site detection and quantification of E. coli in both environment and food safety domains. Graphical abstract