Dongguan University of Technology

To achieve highly selective and portable detection of uranyl (UO₂²⁺) in potentially polluted groundwater, a fluorescent detection method based on UO₂²⁺-triggered protein cleavage was established. An aggregation-induced emission luminogen (AIEgen), 4-aldehyde-4',4″-bis(4-pyridyl)triphenylamine, (CHO-BIPY-TPA, abbreviated as CBPT), was synthesized and labeled onto bovine serum albumin (BSA). The fluorescence of CBPT-BSA was quenched by UO₂²⁺-triggered covalent bond cleavage and protein fragment release. A linear response was observed in the range of 0.1-12 nM with a LOD of 0.01 nM, significantly outperforming the World Health Organization's drinking water limit (60 nM). Selectivity tests confirmed negligible interference from coexisting metal ions as only UO₂²⁺ could triggered protein cleavage. In additon, a portable device was designed for on-site detection of UO₂²⁺ in underground water, which exhibited a linear response in the range of 0.1-15 nM with a LOD of 0.06 nM. The spiked recovery rate reached 85-96 % in environmental water samples, with a relative standard deviation (RSD) below 8 %. The study provided a selective and sensitive screening platform for on-site monitoring UO₂²⁺ in environmental samples.

Detection and real-time tracking of changes in the relative carotenoid content during microbial growth can be extremely challenging. Additionally, analyzing its content cycling time can also be highly difficult. In this study, Raman tweezers were employed to identify the carotenoid in two strains of marine Bacillus spores (designated #2430 and #2966). Further, live-cell dynamic imaging and fluorescence microscopy were utilized to observe the growth morphology and monitor the variations in the relative carotenoid content within the spores. Additionally, a UNet-VGG16-based deep learning algorithm was incorporated to augment the precision of the analysis. The results of this study revealed the presence of varying levels of carotenoids between the two strains of spores across different growth stages. The dividing spores showed a progressive elongation in the cycle of relative carotenoid content fluctuation. In contrast, the non-dividing spores demonstrated more stable cycles, likely due to the lack of carotenoid accumulation, as they required carotenoids for their normal growth rather than cell division. To the best of our knowledge, this study is the first to detect dynamic and real-time variations in the relative carotenoid content during the growth of the two marine Bacillus spore strains, thereby providing novel perspectives on their metabolic characteristics and potential applications.

Zero-dimensional (0D) lead-free Cs₂ZrCl₆ nanocrystals (NCs) have gained increasing attention in the photoluminescence (PL) and scintillation fields owing to their remarkable advantages such as low cost, high chemical yield, and environmental friendliness. Nevertheless, the current Cs₂ZrCl₆ NCs are plagued by low photoluminescence quantum yield (PLQY) and low light yield (LY) due to inherent defects (like chlorine vacancies), which commonly serve as traps and cause non-radiative recombination of excitons. Herein, Cs₂ZrCl₆ NCs with non-radiative defects eliminated, which have a near-unity (98.6 %) PLQY and an ultra-high LY (79,000 photons MeV^-1), were prepared via Mn doping. The experimental characterizations, including X-ray photoelectron spectroscopy (XPS), Raman, steady-state and time-resolved photoluminescence spectroscopy, confirmed the elimination of non-radiative chlorine vacancies in Mn-doped Cs₂ZrCl₆. Density functional theory calculations disclosed that the existence of chloride vacancies in Cs₂ZrCl₆ could introduce deep defect levels within the bandgap, resulting in non-radiative recombination. However, Mn doping could eliminate these trap states. Consequently, the fabricated Mn-doped Cs₂ZrCl₆ scintillator film achieved excellent performance for bendable X-ray detection and imaging, featuring an ultra-low detection limit (35.6 nGy_air s^-1) and an ultra-high spatial resolution (20 lp mm^-1). The work suggests that doping can provide an alternative solution for developing defect-free perovskites with perfect properties.