All-inorganic cesium lead bromide zero-dimensional perovskite Cs4PbBr6 is highly valued for its excellent photoelectric conversion efficiency and exceptional stability. However, its application value in the visible light optical field is limited due to large bandgap and strong ionic and covalent bonds in the crystal structure, which inhibit photon emission in the visible light spectrum. Nonetheless the easily convertible properties among perovskite derivatives bring new opportunities. This study is the first to report the transformation of Cs4PbBr6 nanocrystals into CsPbBr3 nanocrystals, which then grow into nanowires and eventually form micrometer-scale optical microcavities. This innovative approach provides a novel strategy for the fabrication of perovskite micro-nano lasers and strengthens the connections among various perovskite derivatives. The nanowires exhibit excellent quantum size effects and are microdevices with polarized photoluminescence emission capability. Meanwhile, the large-sized microrods exhibit perfect lasing performance with low threshold ~34 μJ cm-2 and high Q-factor ~1229. These high-quality performances make Cs4PbBr6 nanocrystals have significant potential in diverse fields such as optical communication, biomedical applications, photonics and optoelectronics.
As the fluoroquinolone antibiotics, norfloxacin has the advantages of antibacterial properties and efficient inhibition of bacterial DNA replication. Because of its strong binding affinity toward DNA helicases, this compound is chemically stable and exhibits limited biodegradation in environmental matrices. Prolonged use or discharge can enrich antibiotic resistance genes among microbial communities and contribute to persistent contamination. Herein, a nematic liquid crystal (LC) microlaser based on an aptamer recognition was reported and explored its application of norfloxacin ultrasensitive detection in soil. The rapid, real-time and quantitative monitoring of norfloxacin was achieved by exploiting whispering gallery mode (WGM) resonances in LC microdroplets functionalized with a specific aptamer as the molecular recognition element. Through resonance simulation and size-dependent experiments, the feasibility of using LC microlaser as a WGM microresonator was demonstrated. The optimal concentration of CTAB and DNA aptamer was 1 μM and 100 nM, respectively, which could realize the configuration transition of LC microdroplets from radial to bipolar. The devised norfloxacin sensor showed high sensitivity with a detection limit of 0.3 ng/mL, which was an order of magnitude lower than that reported for polarized optical microscope (POM) methods. In addition, the successful detection of various concentrations of norfloxacin in soil samples underscored the practical utility in environmental monitoring. The aptamer-based WGM-LC microlaser provides a highly sensitive approach for norfloxacin detection. The laser recognition probe does not require fluorescent or chromogenic labels, which affords significant advantages for rapid, real-time, and quantitative biosensing. This platform is expected to be extensible to ultrasensitive detection of other drugs, proteins, or environmental pollutants, particularly suited for integration into microfluidic devices for on-site environmental monitoring and public health risk assessment.
危险品化学品经营许可证（带存储）