Fluorescent Sensing with Copper Nanoclusters

Copper nanoclusters (CuNCs) are ultra-small aggregates of copper atoms that exhibit bright photoluminescence. Their remarkable optical properties arise from quantum confinement and surface ligand interactions, enabling sensitive detection of chemical and biological analytes. In recent years, advances in synthetic templates—from DNA strands and proteins to small-molecule ligands—have permitted precise control over cluster size, stabilisation and emission wavelength. The fluorescence response of CuNCs can be modulated by target analytes via mechanisms such as fluorescence quenching, energy transfer and aggregation-induced emission. These properties support a wide array of applications including heavy metal ion monitoring, nucleic acid sensing, biomarker quantification and environmental diagnostics. Cost-effective synthesis, facile functionalisation and good biocompatibility further enhance their potential for point-of-care devices and real-time imaging. Integration with amplification technologies, microfluidics and paper-based platforms has also led to portable, rapid and highly selective sensors with detection limits down to nanomolar or picomolar ranges. Ongoing efforts seek to improve quantum yield, photostability and multiplexing capabilities to meet the demands of clinical, environmental and industrial monitoring.

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Research from all publishers

Recent developments have focused on designing CuNCs for selective detection of heavy metal ions. One comprehensive review outlines various synthetic strategies to tailor CuNC emission and highlights mechanisms by which ions such as mercury, silver and cobalt induce fluorescence changes. These sensors demonstrate low-cost fabrication, broad dynamic ranges and successful recovery of spiked metals in water samples, addressing global concerns over ion pollution.

Another study reports a one-pot synthesis of cysteamine-capped CuNCs that act as luminescent probes for Fe3+ and I− in human urine. The amine group of cysteamine both stabilises clusters and facilitates selective quenching by Fe3+, while controlled aggregation modulates emission shifts for iodide sensing. Detection limits reach submicromolar concentrations and paper-strip assays enable simple visual readouts, highlighting potential for on-site biomedical and environmental diagnostics.

A novel biosensing platform integrates poly(thymine) DNA-templated CuNPs with rolling circle amplification to detect microRNAs. Amplification yields long thymine repeats that template red-emitting CuNPs, switching on fluorescence only in the presence of target sequences. This label-free “off–on” method offers high specificity to single-base mismatches and operates under mild conditions, demonstrating applicability in cancer cell extracts and paving the way for nucleic acid diagnostics without elaborate labelling.

Fluorescent Sensing with Copper Nanoclusters publication trend

The graph below shows the total number of articles in fluorescent sensing with copper nanoclusters across all publications each year (not limited to Nature Index journals).

Technical terms

Copper nanoclusters (CuNCs): Assemblies of a few to tens of copper atoms exhibiting quantum-confined fluorescence.

Fluorescence quenching: Reduction of emission intensity due to interactions with analytes via energy transfer or electron exchange.

Template-directed synthesis: Use of biomolecules or ligands to control the nucleation and growth of metal clusters.

Aggregation-induced emission (AIE): Enhanced fluorescence arising from restricted intramolecular motions in aggregated states.

Rolling circle amplification (RCA): Enzymatic method to generate long single-stranded DNA with repeated sequences, used for signal amplification in biosensors.

References

1. Rational Design Copper Nanocluster-Based Fluorescent Sensors towards Heavy Metal Ions: A Review. Chemosensors (2023).
2. One-pot synthesis of copper nanoconjugate materials as luminescent sensor for Fe3+ and I− detection in human urine sample. Sensing and Bio-Sensing Research (2020).
3. A Label-Free Fluorescent Sensor Based on the Formation of Poly(thymine)-Templated Copper Nanoparticles for the Sensitive and Selective Detection of MicroRNA from Cancer Cells. Chemosensors (2020).