Evaluation of Reaction Parameters Dependent Optical Properties and Its Photovoltaics Performances of CdTe QDs

Y3+@CdTe quantum dot nanoprobe as a fluorescence signal enhancement sensing platform for the visualization of norfloxacin

Quinolone antibiotics (norfloxacin) pose a serious threat to animal and human health due to their misuse and difficulty in being broken down in surface water and food. Rapid and effective detection of norfloxacin (NOR) is essential for environmental testing and ecosystems. In this study, yttrium was coordinated with mercaptopropionic acid (MPA)-modified CdTe quantum dots (QDs) to obtain a novel fluorescence sensor Y³⁺@CdTe QDs for the sensitive detection of NOR. NOR can bind to Y³⁺ to form a complex (NOR-Y³⁺). This complex enhances the luminescence of NOR and blue-shifts to 423 nm. The fluorescence intensity of NOR-Y³⁺ at 423 nm (I₄₂₃) gradually increased with increasing NOR concentration; meanwhile, the fluorescence intensity of CdTe QDs at 634 nm (I₆₃₄) gradually decreased due to aggregation induction. The ratio of I₄₂₃ to I₆₃₄ was used for the quantitative determination of NOR. The linear range of the constructed fluorescent probes was from 1.0 to 150.0 μM, with a detection limit of 31.8 nM. CdTe QDs act as a red fluorescent background, and with the addition of NOR, the color of the system transitions from red to purple and finally blue. This method was rapid (immediate) and visual, providing a simple analysis of various actual samples (tap water, lake water, honey, milk and human serum) for NOR.

A Simple and Effective Visual Fluorescent Sensing Paper-Based Chip for the Ultrasensitive Detection of Mercury Ions in Environmental Water

Traces of mercury ions in environmental water can harm humans and animals. Paper-based visual detection methods have been widely developed for the rapid detection of mercury ions; however, existing methods are not sensitive enough to be used in real environments. Here, we developed a novel, simple and effective visual fluorescent sensing paper-based chip for the ultrasensitive detection of mercury ions in environmental water. CdTe-quantum-dots-modified silica nanospheres were firmly absorbed by and anchored to the fiber interspaces on the paper's surface to effectively avoid the unevenness caused by liquid evaporation. The fluorescence of quantum dots emitted at 525 nm can be selectively and efficiently quenched with mercury ions, and the ultrasensitive visual fluorescence sensing results attained using this principle can be captured using a smartphone camera. This method has a detection limit of 2.83 µg/L and a fast response time (90 s). We successfully achieved the trace spiking detection of seawater (from three regions), lake water, river water and tap water with recoveries in the range of 96.8-105.4% using this method. This method is effective, low-cost, user-friendly and has good prospects for commercial application. Additionally, the work is expected to be utilized in the automated big data collection of large numbers of environmental samples.