Green solvent boosts fluorescence of copper nanoclusters: Achieving ultra-fast fabrication of a universal sensing platform for H2O2-related biomarkers detection.

BACKGROUND

Copper nanoclusters (Cu NCs) exhibit considerable potential for biosensing applications. However, their practical application is hindered by low fluorescence emission intensity and inadequate stability. Conventional aqueous-based synthesis methods have shown limitations in addressing these issues effectively. Consequently, there is an urgent need to develop efficient strategies that can enhance the fluorescence performance of Cu NCs while maintaining the simplicity of preparation. This study proposes the use of polyethylene glycol 200 (PEG 200) as a green solvent for fabricating Cu NCs-based probes.

RESULTS

In PEG-H2O solvent, Cu NCs can be prepared and self-assembled in the presence of Ca2+ ions within just several minutes. The resulting Cu NCs-Ca2+/PEG showed a remarkable 12,000-fold increase in operational life, an 850-fold enhancement in fluorescence quantum yields, and improved stability against pH, temperature, and UV irradiation compared to Cu NCs prepared in H2O. Mechanism studies revealed that PEG 200 reduces dissolved oxygen levels, improves dispersion stability, and offers confinement effects along with Ca2+, enhancing the fluorescence of Cu NCs. Additionally, Cu NCs-Ca2+/PEG can be used for determining H2O2 with a detection limit of 59 nM. By coupling with various oxidases, this platform enabled the sensitive detection of multiple H2O2-related biomarkers, including cholesterol, uric acid, and xanthine.

SIGNIFICANCE: This work represents the first report of using PEG 200 to achieve such remarkable enhancements in the fluorescence of Cu NCs, without hazardous chemicals or controlled environments. By addressing long-standing challenges in fluorescence emission intensity and stability, this approach paves the way for constructing versatile sensing platforms for H2O2-involved biological processes and oxidative stress-related diagnostics.