Growth optimization of single-phase novel colloidal perovskite Cs3Bi2I9 nanocrystals and Cs3Bi2I9@SiO2 core-shell nanocomposites for bio-medical application.

Lead-free halide perovskites have gained attention in recent years as viable materials with more distinctive characteristics than conventional semiconductor materials. Lead-free Cs3Bi2I9 colloidal perovskite nanocrystal is chosen to eliminate its single-phase synthesis difficulty and implement the material in bioimaging applications. Nanostructured Cs3Bi2I9 perovskite composites were coated with a thin coating of SiO2 by an in situ tetraethyl orthosilicate/(3-aminopropyl)trimethoxysilane injection growth method to enhance their stability in aqueous medium and biocompatibility. Single-phase novel Cs3Bi2I9 colloidal perovskite nanocrystal synthesis was successfully developed and optimized by adopting different synthetic conditions with varied experimental parameters. Characterization studies, including X-ray diffractometry and transmission electron microscopy, confirm the hexagonal structure of Cs3Bi2I9 crystals and their cubic morphology. A broad emission peak in the red region was captured for pure and composite perovskite under different excitation wavelengths and was observed using a UV-visible spectrophotometer. Bioimaging of Cs3Bi2I9@SiO2 composites incorporated with L929 cells was conducted using an inverted fluorescence microscope under blue and green excitation. The results obtained from bioimaging studies indicated that the Cs3Bi2I9@SiO2 nanocomposites entered the cell field and exhibited an emission under excitation. The non-toxic behavior of the synthesized Cs3Bi2I9@SiO2 composites was demonstrated using MTT cytotoxicity assay in L929 fibroblast mouse cells, showing better cell compatibility.

Embellishing 2-D MoS2 Nanosheets on Lotus Thread Devices for Enhanced Hydrophobicity and Antimicrobial Activity.

Herein, we report cellulose-based threads from Indian sacred Lotus (Nelumbo nucifera) of the Nymphaceae family embellished with MoS2 nanosheets for its enhanced hydrophobic and antimicrobial properties. MoS2 nanosheets synthesized by a coprecipitation method using sodium molybdate dihydrate (Na2MoO4·2H2O) and thioacetamide (CH3CSNH2) were used as a sourse for MoS2 particle growth with cellulose threads extracted from lotus peduncles. The size, crystallinity, and morphology of pure and MoS2-coated fibers were studied using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). the XRD pattern of pure lotus threads showed a semicrystalline nature, and the threads@MoS2 composite showed more crystallinity than the pure threads. SEM depicts that pure lotus threads possess a smooth surface, and the MoS2 nanosheets growth can be easily identified on the threads@MoS2. Further, the presence of MoS2 nanosheets on threads was confirmed with EDX elemental analysis. Antimicrobial studies with Escherichia coli and Candida albicans reveal that threads@MoS2 have better resistance than its counterpart, i.e., pure threads. MoS2 sheets play a predominant role in restricting the wicking capability of the pure threads due to their enhanced hydrophobic property. The water absorbency assay denotes the absorption rate of threads@MoS2 to 80%, and threads@MoS2 shows no penetration for the observed 60 min, thus confirming its wicking restriction. The contact angle for threads@MoS2 is 128°, indicating its improved hydrophobicity.