Biofabrication and characterization of cyanobacteria derived ZnO NPs for their bioactivity comparison with commercial chemically synthesized nanoparticles.

Due to unique properties of the nanoparticles (NPs) with biocompatibility, their application as drug in drug delievery and diagnostics, the recent scientific branch nanotechnology has emerged as hope in modern medicine. Zinc oxide nanoparticles (ZnO NPs) have gained tremendous interest due to their potential use as chemotherapeutic and antimicrobial agents. They are included in the category of "generally recognized as safe (GRAS) metal oxide". There is an urgent need for developing additional sources of ZnO NPs. Therefore, in the present study 30 cyanobacterial extracts were screened for ZnO NPs synthesis.. The color change of the reaction mixture from blue to pale white indicated the synthesis of ZnO NPs. It was further confirmed by UV-Visible spectroscopy that showed the absorption peak at 372 nm. The SEM analysis during screening revealed that Oscillatoria sp. synthesized smallest ZnO NPs (~40 nm) that were further optimized for their higher yield by altering reaction conditions (pH, temperature, reaction time, concentration of extract and metal precursor). Best conditions for ZnO NPs synthesis are (0.02 M zinc nitrate, 10 ml of extract volume, pH 8, at 80 °C for 3 h). The NPs were purified through calcination at 350°C and characterized by UV-Vis, FTIR, XRD, SEM-EDAX, TEM, Zeta potential and DLS analysis. The comparative analysis of purified biogenic ZnO NPs with commercial chemically synthesized ZnO NPs (CS), exhibited their superior nature as antioxidant and anti-bacterial agent against both gram-positive and gram-negative bacteria. Synergistic effects of biogenic ZnO NPs and streptomycin additionally favored for their future use as a potential biomedical agent.

Synthesis, purification and characterization of Plectonema derived AgNPs with elucidation of the role of protein in nanoparticle stabilization.

Driven by the need to biosynthesize alternate biomedical agents to prevent and treat infection, silver nanoparticles have surfaced as a promising avenue. Cyanobacteria-derived nanomaterial synthesis is of substantive interest as it offers an eco-friendly, cost-effective, sustainable, and biocompatible route for further development. In the present study optimal conditions for synthesis of silver nanoparticles (AgNPs) were 1 : 9 v/v [cell extract: AgNO3 (1 mM)], pH 7.4, and 30 °C reaction temperatures. Synthesis of nanoparticles was monitored by UV-vis spectrophotometry and the maximum absorbance was observed at a wavelength of 420 nm. SEM with EDX analysis confirmed 96.85% silver by weight which revealed the purity of AgNPs. TEM & XRD analysis exhibited a particle size of ∼12 nm with crystalline nature. FTIR analysis confirmed the presence of possible biomolecules involved in the synthesis and stabilization of AgNPs. Decapping of AgNPs followed by SDS-PAGE, LCMS and MALDI TOF analysis elucidates the proteinaceous nature of the capping and stabilizing agent. Cyanobacterial-derived capped AgNPs showed more cytotoxicicity towards a non-small cell lung cancer (A549) cell line, free radical scavenger and an antimicrobial than de-capped AgNPs. In addition they showed significant synergistic characteristics with antibiotics and fungicides. The test revealed that the capped AgNPs were biocompatible with good anti-inflammatory properties. The blend of antimicrobial and biocompatible properties, coupled with their intrinsic "green" and facile synthesis, made these biogenic nanoparticles particularly attractive for future applications in nanomedicine.