Highly luminescent copper nanoclusters as temperature sensors and “turn off” detection of oxytetracycline

Polyethyleneimine (PEI), playing roles as a templating agent, has been successfully applied to prepare blue-green-emitting copper nanoclusters (Cu [email protected]) on the basis of a rapid chemical reduction synthesis method. Some characterization methods, such as fluorescence spectrophotometer, UV spectrophotometer, Fourier transform infrared instrument (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and fluorescence lifetime, were used for the analysis of physical, chemical and optical properties of Cu [email protected] The Cu [email protected] displayed a blue-green emission wavelength at 485 nm and the corresponding quantum yield (QY) was 2.24%. Subsequently, the as-synthesized Cu [email protected] were applied for the trace analysis of oxytetracycline on the basis of the inner filter effect (IFE) and static quenching, which caused the fluorescence to be effectively quenched. Additionally, this proposed platform based on the Cu [email protected] for oxytetracycline sensing possessed an excellent linear range from 0.5 to 300 μM with a lower detection limit of 0.032 μM (S/N = 3) and correlation coefficient R2 of 0.9972. Surprisingly, as the temperature increased, the fluorescence intensities of Cu [email protected] decreased gradually. Thence, the Cu [email protected] could be applied for the sensing of temperature. Finally, the practicability of the detection method have been successfully verified by analyzing oxytetracycline in real samples, enlarging its applicable fields for oxytetracycline sensing.