Silver nanoparticles biosynthesized from secondary metabolite producing marine actinobacteria and evaluation of their biomedical potential.

Biosynthesis of silver nanoparticles (AgNPs) from marine actinobacteria offers a promising avenue for exploring bacterial extracts as reducing and stabilizing agents. We report extracellular extracts of Rhodococcus rhodochrous (MOSEL-ME29) and Streptomyces sp. (MOSEL-ME28), identified by 16S rRNA gene sequencing for synthesis of AgNPs. Ultrafine silver nanoparticles were biosynthesized using the extracts of R. rhodochrous and Streptomyces sp. and their possible therapeutic applications were studied. The physicochemical properties of nanoparticles were established by HR-SEM/TEM, SAED, UV-Vis, EDS, XRD, and FTIR. UV-Vis spectra displayed characteristic absorption at 430 nm and 412 nm for AgNPs from Streptomyces sp. (S-AgNPs) and Rhodococcus sp. (R-AgNPs), respectively. HR-SEM/TEM, XRD, EDS analysis confirmed the spherical shape, crystalline nature, and elemental formation of silver. Crystallite or grain size was deduced as 5.52 nm for R-AgNPs and 35 nm for S-AgNPs. Zeta-potential indicated electrostatic negative charge for AgNPs, while FTIR revealed the presence of diverse functional groups. Disc diffusion assay indicated the broad-spectrum antibacterial potential of S-AgNPs with the maximum inhibition of B. subtilis while R-AgNPs revealed potency against P. aeruginosa at 10 µg/mL concentration. Biogenic AgNPs revealed antileishmanial activity and the IC50 was calculated as 164 µg/mL and 184 µg/mL for R-AgNPs and S-AgNPs respectively. Similarly, the R-AgNPs and S-AgNPs revealed anti-cancer potential against HepG2 and the IC50 was calculated as 49 µg/mL and 69 µg/mL for R-AgNPs and S-AgNPs, respectively. Moreover, the antioxidant activity showed significant results. MTT assay on RD cells, L20B cells, and Hep-2C indicated intensification in viability by reducing the concentration of R-AgNPs and S-AgNPs. The R-AgNPs and S-AgNPs inhibited sabin-like poliovirus (1TCID50 infection in RD cells). Furthermore, hemocompatibility at low concentrations has been confirmed. Hence, it is concluded that biogenic-AgNPs has the potential to be used in diverse biological applications and that the marine actinobacteria are an excellent resource for fabrication of AgNPs.

Precursor effects on the physical, biological, and catalytic properties of Fagonia indica Burm.f. mediated zinc oxide nanoparticles.

We report a facile, green and precursor-based comparative study on the biosynthesis of zinc oxide (ZnO) nanoparticles (NPs) using anticancerous Fagonia indica as effective chelating agent. Biosynthesis was carried out using zinc sulfate and zinc acetate as precursor salts to make ZnOS and ZnOA NPs under similar experimental conditions which were characterized extensively for physical and biological properties. Scherrer equation deduced a mean crystallite size of ~23.4 nm for ZnOA NPs and ~41 nm for ZnOS NPs. The nature of the NPs was compared using UV, diffuse reflectance spectra, Fourier transform infrared spectroscopy, thermogravimetric analysis-DTA, selected area electron diffraction, EDS, zeta potential, high resolution (HR)-SEM, and HR-TEM. Detailed in vitro pharmacognostic activities revealed a significant therapeutic potential for ZnOA and ZnOS . Potential antimicrobial activities for the NPs and their nanocosmeceutical formulations are reported. ZnOA NPs were more cytotoxic to Leishmania tropica as compared to ZnOS . Significant antioxidant and protein kinase inhibition was obtained. The hemolytic assay indicated a hemocompatible nature of both ZnOA and ZnOS NPs. Catalytic degradation of crystal violet dye (CVD) by NPs was examined under different parameters (light, dark, UV). Furthermore, sonophotocatalytic degradation of CVD was also studied. Our results suggested that precursor can have a significant effect on the physical, biological, and catalytic properties of the NPs. In future, we recommend different other in vitro, in vivo biological activities, and mechanistic studies of these as-synthesized NPs.

Greener synthesis of ZnO and Ag-ZnO nanoparticles using Silybum marianum for diverse biomedical applications.

AIM: To investigate the physical and biological properties of Silybum marianum inspired ZnO nanoparticles (NPs), Ag-ZnO heterostructures. Experiment: Nanoparticles were characterized using ultraviolet-visible and infrared spectroscopy, x-ray diffraction, high resolution electron microscopy, ζ potential and thermo-gravimetric analysis etc. Results: Ag-ZnO-NPs indicated slightly higher antimicrobial potential then ZnO-NPs. Good antileishmanial (IC50 = 246 µg/ml for Ag-ZnO; 341 µg/ml for ZnO) and antioxidant potential while moderate enzyme inhibition is reported. 2, 2-Diphenyl 1-picrylhydrazyl radical scavenging of Ag-ZnO was higher relative to ZnO-NPs. Nanocosmaceutical formulation of nanoparticles indicated stable antimicrobial performance. CONCLUSION: Biosynthesized nanoparticles indicated interesting biological properties and should be subjected to further research to establish their pharmacological relevance.

Biosynthesis of pure hematite phase magnetic iron oxide nanoparticles using floral extracts of Callistemon viminalis (bottlebrush): their physical properties and novel biological applications.

Aqueous floral extracts of Callistemon viminalis were used to synthesize Fe2O3 nanoparticles (IONPs) which were intensively characterized through UV-vis, X-ray diffraction, HR-SEM/HR-TEM, Fourier- transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDS). Their physical properties were studied in response to different annealing temperatures. It was observed that the increase in the annealing temperature produced small-sized nanoparticles. The nanoparticle size was calculated as 32, 26 and 22 nm for annealing at 300, 400 and 500 °C, respectively. The magnetic nature of the bioinspired IONPs was revealed by superconducting quantum interference device (SQUID). Their antibacterial potential was investigated against nine pathogenic bacterial strains (gram positive and gram negative) using disc diffusion method while their MIC was calculated using broth dilution assay. Bioinspired IONPs were found to be highly effective against HepG2 cells (IC50=20 µg/mL). Moderate antileishmanial activities against the promastigotes and amastigotes cultures are reported. Moderate acetylcholine esterase (AchE), butylcholine esterase (BchE) and α-Glycosidase inhibition are reported. Additional assessment of the biocompatibility was performed using haemolytic activity on the freshly isolated human red blood cells and macrophages. Furthermore, the antioxidant activities, including TAC, DPPH and TRP were also performed. Our results indicate that the biogenic and magnetic Fe2O3 can be used for diverse biomedical applications.

Sageretia thea (Osbeck.) mediated synthesis of zinc oxide nanoparticles and its biological applications.

AIM: To investigate the physical and biological properties of bioinspired zinc oxide (ZnO) nanoparticles via aqueous leaf extracts of Sageretia thea. EXPERIMENTAL: Nanoparticles of size approximately 12.4 nm were extensively characterized. In vitro antimicrobial, cytotoxic, biocompatible and enzyme inhibition assays were performed. RESULTS: Significant antimicrobial activities with and without UV illumination are reported. Bioinspired ZnO nanoparticles were found effective against fungal strains. MTT assay was performed to check the leishmanicidal activity against promastigotes (IC50: 6.2 µg/ml) and amastigotes (IC50: 10.87 µg/ml) of Leishmania tropica. Brine shrimp lethality was also indicated by bioinspired ZnO nanoparticles (IC50: 21.29 µg/ml). CONCLUSION: Hemocompatible nature of bioinspired nanoparticles was revealed. Furthermore, the antioxidant activities were performed. In addition, significant protein kinase while insignificant alpha amylase inhibition were recorded.