Copper nanoclusters stabilized by D-penicillamine for ultrasensitive and visual detection of oxytetracycline

Copper nanoclusters (DPA@CuNCs) with red fluorescence were successfully synthesized by a one-step method based on D-penicillamine (DPA), which acted not only as a reducing agent but also as a stabilizer. The products were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, particle-size analysis, ultraviolet-visible spectrophotometry, and fluorescence spectrometry. When the excitation wavelength was 280 nm, DPA@CuNCs emitted bright red fluorescence at 640 nm with a fluorescence quantum yield of 5.8 %. Due to the inner filter effect, oxytetracycline (OTC) effectively quenched the fluorescence of DPA@CuNCs, and then DPA@CuNCs were applied to the trace detection of OTC. The method showed a good linear range for OTC from 5 to 60 & mu;mol/L, with a detection limit of 0.026 & mu;mol/L and a correlation coefficient R2 of 0.9983. Moreover, a paper-based sensor for the visual detection of OTC has been developed, which can conveniently and rapidly distinguish the concentration ranges of OTC through the color changes of the test papers.

Automated summary

Red fluorescent copper nanoclusters (DPA@CuNCs) were synthesized using D-penicillamine as a reducing agent and stabilizer. The synthesized products were characterized using various techniques and exhibited a bright red fluorescence with a quantum yield of 5.8% when excited at 280 nm. The fluorescence of DPA@CuNCs was effectively quenched by oxytetracycline (OTC), enabling its trace detection and a paper-based sensor was developed for the visual detection of OTC.