Xuan Lu,Yang Hu,Jiazhuang Guo,Cai-Feng Wang,Su Chen
All-inorganic halide perovskite nanocrystals (PNCs) have drawn increasing attention owing to their splendid optical properties. However, such nanomaterials suffer from intrinsic instability, greatly limiting their practical application. Meanwhile, environmental regulation has restricted the emissions of volatile organic compounds (VOCs), initiating a search for alternative approaches to PNC synthesis and film forming. Herein, fiber-spinning chemistry (FSC) is proposed for easy-to-perform synthesis of highly stable PNC fibrous films. The FSC process utilizes spinning fibers as reactors, reducing the generation of VOCs. This method enables the fabrication of CsPbX 3 (X = Cl, Br, I) PNCs/poly(methyl methacrylate)/thermoplastic polyurethanes fibrous films at room temperature in one step, exhibiting tunable emission between 450 and 660 nm. Significantly, the in situ generation of PNCs in hydrophobic core–shell nanofibers results in highly improved fluorescence stability. PNCs/polymer fibrous films keep constant in photoluminescence (PL) after storage at atmosphere for 90 d and retain 82% PL after water immersion for 120 h (vs fluorescence quenching in 10 d in air or 5 h in water for pristine PNCs). The PNCs/polymer fibrous films endowed with superior optical stability and great flexibility show promising potentials in flexible optoelectronic applications. This work paves a facile way toward high-performance nanoparticles/polymer fibrous films.
Long Chen,Ying Wang,Enxian Yuan,Xiaoya Hu,Yun Shu,Juewen Liu,Huan Pang
Fluorescent nanozymes allow the use of both fluorescence and catalytic functions for theragnostic and bioanalytical applications. However, few fluorescent nanozymes with both high fluorescence yield and high catalytic activities are available. CsPbX 3 perovskite nanocrystals (PNCs) have strong fluorescence but very weak catalytic activities. Here, a microenvironment electron transfer regulation strategy is proposed to enhance the nanozymatic activities and stability of PNCs through the incorporation of Fe metal-organic framework (MOF). By in suit growth of an amphiphilic polymer (octylamine-modified polyacrylic acid) capped PNCs on MOF, the oxidase (OXD)-like activity of PNCs is enhanced sevenfold. X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) characterizations revealed that forming the composition results in valence state shifts of the Fe atoms, indicating an electron transfer from PNCs to MOF enabled by the built-in electric field, which improved the catalytic activities. Moreover, the nanocomposite also displays peroxidase (POD)-like activity, and its dual enzyme-like catalytic mechanism and activities are studied experimentally and theoretically. At last, a nanozyme cascade catalytic system based on the dual mimic enzyme of PNCs@MOF is constructed for ratiometric fluorescence biosensing of ascorbic acid with high sensitivity. This work provides an attractive fluorescent nanozyme, greatly expanding its application in bioanalysis.
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