Biogenic Synthesis of Fluorescent Carbon Dots (CDs) and Their Application in Bioimaging of Agricultural Crops.

Fluorescent nanoparticles have a transformative potential for advanced sensors and devices for point-of-need diagnostics and bioimaging, bypassing the technical burden of meeting the assay performance requirements. Carbon dots (CDs) are rapidly emerging carbon-based nanomaterials. Regardless of their fate, they will find increasing applications. In this study, a simple approach for synthesizing CDs from fruit peels was developed. The CDs were fabricated from Annona squamosa (L.) peels using a carbonization technique through microwave-assisted hydrothermal digestion at temperatures around 200 °C. Synthesized CDs were detected using a UV transilluminator for the preliminary confirmation of the presence of fluorescence. UV-Vis spectrophotometry (absorbance at 505 nm) analysis, zeta potential measurement (-20.8 mV), nanoparticles tracking analysis (NTA) (average size: 15.4 nm and mode size: 9.26 nm), photoluminescence, and Fourier transform infrared (FT-IR) analysis were used to identify the capping functional groups on the CDs. The total quantum yield exhibited was 8.93%, and the field emission scanning electron microscopy (FESEM) showed the size range up to 40 nm. The germinating mung bean (Vigna radiata (L.)) seeds were incubated with biogenically synthesized CDs to check the absorption of CDs by them. The fluorescence was observed under a UV-transilluminator in the growing parts of seeds, indicating the absorption of CDs during the germination, development, and growth. These fluorescent CDs could be used as a bioimaging agent. This novel method of synthesizing CDs was found to be eco-friendly, rapid, and cost-effective.

Biocompatible antimicrobial cotton fibres for healthcare industries: a biogenic approach for synthesis of bio-organic-coated silver nanoparticles.

Cotton fibres coated with biogenically fabricated silver nanoparticles (SNPs) are most sought material because of their enhanced activity and biocompatibility. After successful synthesis of SNPs on cotton fibres using leaf extract of Vitex negundo Linn, the fibres were studied using diffuse reflectance spectroscopy, scanning electron microscopy, nanoparticle tracking analysis, energy dispersive X-ray, and inductively coupled plasma atomic emission spectrometry. The characterisation revealed uniformly distributed spherical agglomerates of SNPs having individual particle size around 50 nm with the deposition load of 423 µg of silver per gram of cotton. Antimicrobial assay of cotton-SNPs fibres showed effective performance against pathogenic bacteria and fungi. The method is biogenic, environmentally benign, rapid, and cost-effective, producing highly biocompatible antimicrobial coating required for the healthcare industry.

Synthesis, characterization and biological activities of mixed ligand Zr(IV) complexes.

Mixed ligand ternary Zr(IV) complexes of type [M(Q)2LNO3xH2O] have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/O-donor amino acids (HL) such as L-serine, L-alanine and glycine as secondary ligands. These complexes were characterized on the basis of elemental analysis, conductance measurement, spectral and thermal studies. The molar conductance study of the complexes in DMF solvent signifies their non-electrolytic nature whereas the thermal analyses specify presence of a coordinated water molecule. The complexes were tested for antifungal and antibacterial activity by using agar well diffusion bioassay. The antibacterial activity was tested against the pathogenic bacteria Staphylococcus aureus and Enterococcus faecium. The results obtained were evaluated with antibacterial standard vancomycin. The antifungal activity was tested against Candida albicans, Candida krusei, Aspergillus fumigatus and the results obtained were compared with antifungal standard amphotericin B. The complexes were also screened for cytotoxicity studies against Ehrlich ascites cells and Daltons lymphoma ascites cells and show very low cytotoxicity.