Laurus nobilis leaf extract mediated green synthesis of ZnO nanoparticles: Characterization and biomedical applications.

The present study reports the green synthesis of zinc oxide nanoparticles using the aqueous leaf extract of Laurus nobilis (Ln-ZnO NPs) by co-precipitation method. The synthesized Ln-ZnO NPs were characterized by UV-Vis spectroscopy, FTIR, XRD, TEM, SEM and EDX. Ln-ZnO NPs were crystalline in nature, flower like and have hexagonal wurtzite structure with a mean particle size of 47.27nm. The antibacterial activity of Ln-ZnO NPs was greater against Gram positive (Staphylococcus aureus) bacteria than Gram negative (Pseudomonas aeruginosa) bacteria. The zone of inhibition against S. aureus was 11.4, 12.6 and 14.2mm at 25, 50 and 75μgmL-1. The zone of inhibition against P. aeruginosa was 9.8, 10.2 and 11.3mm at 25, 50 and 75μgmL-1. The light and confocal laser scanning microscopic images evidenced that Ln-ZnO NPs effectively inhibited the biofilm growth of S. aureus and P. aeruginosa at 75μgmL-1. The cytotoxicity studies revealed that Ln-ZnO NPs showed no effect on normal murine RAW264.7 macrophage cells. On the other hand, Ln-ZnO NPs were effective in inhibiting the viability of human A549 lung cancer cells at higher concentrations of 80μgmL-1. The morphological changes in the Ln-ZnO NPs treated A549 lung cancer cells were observed under phase contrast microscope.

Vijayakumar S ，Vaseeharan B ，Malaikozhundan B ，Shobiya M ... -  《-》

Green synthesis of ZnO nanoparticles using Solanum nigrum leaf extract and their antibacterial activity.

In the present investigation, we have described the green biosynthesis of ZnO nanoparticles (NPs) by using Solanum nigrum as capping agent. The functionalization of ZnO particles through S. nigrum leaf extract mediated bioreduction of ZnO was investigated through UV-Vis DRS, photoluminescence (PL), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), thermal gravimetric-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS) and antibacterial activities. UV-Vis-DRS studies revealed that the indirect band gap 3.38 eV and photoluminescence study reveals the blue emission at 402, 447, 469 and 483 nm and the green emission at 529 nm respectively. In addition, the synthesized NPs are wurtzite hexagonal structure with an average grain size lies between 20 and 30 nm were found from XRD analysis. Further, FT-IR spectra revealed the functional groups and the presence of protein as the stabilizing agent for surrounding the ZnO NPs. The diameter of the NPs in the range of 20-30 nm was found from FE-SEM study. TEM analysis was investigated the ZnO NPs as a quasi-spherical in shape and their diameter at around 29.79 nm. Finally, the current study has clearly demonstrated that the particle size variations and surface area to volume ratios of ZnO NPs are responsible for significant higher antibacterial activities. Further, the present investigation suggests that ZnO NPs has the potential applications for various medical and industrial fields so, that the investigation is so useful and helpful to the scientific communities.

Ramesh M ，Anbuvannan M ，Viruthagiri G 《-》

Biosynthesis, characterization and antimicrobial activities of zinc oxide nanoparticles from leaf extract of Mentha pulegium (L.).

The synthesis of metal and semiconductor nanoparticles is an expanding research area due to the potential applications in the development of novel technologies. In the present study, a simple and eco-friendly synthesis of zinc oxide nanoparticles (ZnO NPs) using leaf extract of Mentha pulegium L. has been used. The biosynthesized ZnO NPs were characterized various techniques such as UV-Vis absorption spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FT-IR). The XRD data showed the crystalline nature of the nanoparticles and EDX measurements indicated the high zinc content of 56.26% and also oxygen with 43.74%. FT-IR confirmed the presence of functional groups of both leaf extract and ZnO NPs. The particles size and morphology determined from FE-SEM and TEM and UV visible absorbance spectrum of ZnO NPs exhibited the absorbance band at 370 nm. The synthesized ZnO nanoparticles as potential antibacterial agent has been studied on Escherichia coli and Staphylococcus aureus. These results indicate that aqueous extract of Mentha pulegium (L.) are effective reducing agents for green synthesis of ZnO NPs with significant antimicrobial potential.

Rad SS ，Sani AM ，Mohseni S 《-》

Plectranthus amboinicus leaf extract mediated synthesis of zinc oxide nanoparticles and its control of methicillin resistant Staphylococcus aureus biofilm and blood sucking mosquito larvae.

In this study, zinc oxide nanoparticles were biologically synthesized using the leaf extract of Plectranthus amboinicus (Pam-ZnO NPs). The synthesized Pam-ZnO NPs were characterized by UV-Vis spectrophotometer, FTIR, TEM and XRD analysis. TEM analysis of Pam-ZnO NPs showed the average size of about 20-50 nm. Pam-ZnO NPs control the growth of methicillin-resistant Staphylococcus aureus biofilms (MRSA ATCC 33591) at the concentration of 8-10 μg/ml. Confocal laser scanning microscope (CLSM) images revealed that Pam-ZnO NPs strongly inhibited the biofilm forming ability of S. aureus. In addition, Pam-ZnO NPs showed 100% mortality of fourth instar mosquito larvae of Anopheles stephensi, Culex quinquefasciatus and Culex tritaeniorhynchus at the concentration of 8 and 10 μg/ml. The histopathological studies of Pam-ZnO NPs treated A. stephensi and C. quinquefasciatus larvae revealed the presence of damaged cells and tissues in the mid-gut. The damaged tissues suffered major changes including rupture and disintegration of epithelial layer and cellular vacuolization. The present study conclude that Pam-ZnO NPs showed effective control of S. aureus biofilms and mosquito larvae by damaging the mid gut cells.

Vijayakumar S ，Vinoj G ，Malaikozhundan B ，Shanthi S ，Vaseeharan B ... -  《-》

RETRACTED: Facile, eco-friendly and template free photosynthesis of cauliflower like ZnO nanoparticles using leaf extract of Tamarindus indica (L.) and its biological evolution of antibacterial and antifungal activities.

In the present investigation, we chose the very simple and eco-friendly chemical method for synthesis of zinc oxide nanoparticles from leaf extract of Tamarindus indica (L.) (T. indica) and developed the new green route for synthesis of nanoparticles. Formed product has been studied by UV-vis absorption spectroscopy, Photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and with corresponding energy dispersive X-ray analysis (EDX). Mainly, the present results depicted that the synthesized nanoproducts are moderately stable, hexagonal phase, roughly spherical with maximum particles in size range within 19-37 nm in diameter. The antibacterial and fungal activities of aqueous extracts of T. indica were ended with corresponding disk diffusion and Minimum Inhibitory Concentration (MIC). The highest mean zones of inhibition were observed in the ZnO NPs (200 μg/mL) against Staphylococcus aureus (13.1±0.28). Finally, it can be concluded that microbial activity of ZnO NPs has more susceptible S. aureus than the other micro organisms. Further, the present investigation suggests that ZnO NPs has the potential applications for various medical and industrial fields.

Elumalai K ，Velmurugan S ，Ravi S ，Kathiravan V ，Ashokkumar S ... -  《-》