Eco-friendly preparation of zinc oxide nanoparticles using Tabernaemontana divaricata and its photocatalytic and antimicrobial activity.

The present work reports the green synthesis of Zinc Oxide Nanoparticles (ZnO NPs) using aqueous Tabernaemontana divaricata green leaf extract. ZnO NPs have been characterized by X-ray diffraction (XRD), Ultra Violet-Visible (UV-Vis) studies, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Fourier Transform-Infra Red (FT-IR) analysis. XRD pattern analysis confirms the presence of pure hexagonal wurtzite crystalline structure of ZnO. The TEM images reveal the formation of spherical shape ZnO NPs with the sizes ranging from 20 to 50 nm. The FT-IR analysis suggests that the obtained ZnO NPs have been stabilized through the interactions of steroids, terpenoids, flavonoids, phenyl propanoids, phenolic acids and enzymes present in the leaf extract. Mechanism for the formation of ZnO NPs using Tabernaemontana divaricata as bioactive compound is proposed. As prepared ZnO NPs reveals antibacterial activity against three bacterial strains, Salmonella paratyphi, Escherichia coli and Staphylococcus aureus. The ZnO NPs shows higher antibacterial activity against S. aureus and E. coli and lesser antibacterial activity against S. paratyphi compared to the standard pharmaceutical formulation. Photocatalytic activity of synthesized ZnO NPs was analyzed for methylene blue (MB) dye degradation with sunlight. Almost complete degradation of dye occurred in 90 min. This nano-ZnO, prepared by eco-friendly method will be much useful for dye removal and bacterial decontamination.

Raja A ，Ashokkumar S ，Pavithra Marthandam R ，Jayachandiran J ，Khatiwada CP ，Kaviyarasu K ，Ganapathi Raman R ，Swaminathan M ... -  《-》

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 《-》

Photocatalytic and antibacterial properties of phytosynthesized CeO2 NPs using Moringa oleifera peel extract.

Biosynthetic methods are alternative approaches which are much safer than the normal techniques (physical and chemical) used for the methods for synthesis of metal nanoparticles. The benefits are sample as it is economic and environment friendly. Herein present investigation, we have reported a microwave mediated eco-friendly synthetic approach for preparing cerium oxide (CeO2) nanoparticles. Here, we used Moringa oleifera peel as the stabilizing and reducing agent towards synthesize of Ce2O NPs via microwave irradiation. The NPs were further characterized using UV-Vis, FT-IR, XRD and HR-TEM techniques. The FTIR analysis confirmed the phytochemical involvement in NPs stabilization. The crystallinity of CeO2 nanoparticles are well demonstrated through X-ray Diffraction and HR-TEM. The TEM images reveal the spherical shape of the CeO2 NPs having an average size of 45nm. Additionally, these CeO2 NPs were used successfully as a catalyst in the degradation of the dye, crystal violet. Also the antibacterial activity of the synthesized CeO2 NPs was evaluated using Staphylococcus aureus (Gram positive bacteria) and Escherichia coli (Gram negative bacteria). CeO2 NPs showed better activity on E. coli than S. aureus. We have demonstrated an eco-friendly preparation of CeO2 nanoparticles, a good photocatalyst and having better antibacterial properties.

Surendra TV ，Roopan SM 《-》

Green synthesis of ZnO and Cu-doped ZnO nanoparticles from leaf extracts of Abutilon indicum, Clerodendrum infortunatum, Clerodendrum inerme and investigation of their biological and photocatalytic activities.

In the present study, green synthesis and determination of the antioxidant, antibacterial, antifungal, anticancer and photocatalytic properties of the resultant Cu-doped zinc oxide nanoparticles (NAPs) were carried out. A superficial method (solution combustion method) was employed for the synthesis of un-doped ZnO NAPs from aqueous extract of Abutilon indicum, and synthesis of Cu-doped ZnO NAPs from aqueous extracts of Clerodendrum infortunatum (M1 NAPs) and Clerodendrum inerme (M2 NAPs). The synthesized un-doped ZnO, M1 and M2 NAPs were characterized by different spectroscopic techniques like Ultraviolet-visible (UV-Vis), Fourier Transform-Infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). The antibacterial and antifungal activities of M1 and M2 NAPs were determined by agar diffusion method, while their antioxidant properties were assessed through DPPH radical scavenging and ferric thiocyanate (FTC) and assays. Under sunlight irradiation, photocatalytic disintegration potential of M1 and M2 NAPs were determined by the degradation of Acid Black 234 dye. Results from FT-IR, XRD, EDX and SEM confirmed successful synthesis, crystalline nature, and spheroid-to-rod-like shapes of un-doped ZnO, M1 and M2 NAPs, with grain sizes of 16.72nm, 17.49nm and 20.73nm; and band gap energies of 3.37eV, 3.36eV and 3.31eV, respectively. The NAPs were good catalysts for effective degradation of Acid Black 234. They also exhibited remarkable antioxidant and anticancer activities. Significant antibacterial activity was shown by M2 NAPs against E. coli, S. aureus, Klebsiella and B. subtilis, with zones of inhibition (ZOIs) of 13±0.09, 14±0.01, 18±0.07 and 20±0.10, respectively. Significant antifungal potential was also produced by M2 NAPs at 5mg with ZOIs of 17±0.07 and 24±0.08 against A. niger and T. harzianum, respectively. These results indicate that aqueous extracts of A. indicum, C. infortunatum and C. inerme are effective reducing agents for green synthesis of un-doped ZnO, and Cu-doped ZnO NAPs with significant antimicrobial, antioxidant, and antifungal potential. Thus they are good candidates for future therapeutic applications.

Khan SA ，Noreen F ，Kanwal S ，Iqbal A ，Hussain G ... -  《-》

Synthesis and characterization of phytochemical fabricated zinc oxide nanoparticles with enhanced antibacterial and catalytic applications.

A "green route" to fabricate nanoparticles has emerged as a revolutionary approach. The reported work presents a green approach to synthesize ZnO nanoparticles using Conyza canadensis plant leaves extract. The synthesis of ZnO was conducted at two different temperatures i.e. 30 °C and 80 °C. ZnO nanoparticles prepared at 80 °C were smaller in size and exhibited spherical morphology. The prepared nanomaterials were examined for the reduction of organic dyes i.e. methylene blue and methyl orange. The fabricated ZnO nanoparticles synthesized at 80 °C were found to be highly active for the reduction of aforementioned dyes with 94.5% reduction of MO and 85.3% reduction of MB in 45 min and 20 min respectively. The rate constant (k) for this reduction of MO was found to be 5.781 × 10-3 s-1 in the absence of a catalyst and 5.843 × 10-2 s-1 in the presence of ZnO NPs catalyst. The rate constant (k) for the reduction of MB was found to be 4.7 × 10-3 s-1 in the absence of a catalyst and 9.936 × 10-3 s-1 in the presence of ZnO NPs catalyst. ZnO nanoparticles synthesized at 80 °C were examined for their antibacterial activity. The biogenic ZnO nanoparticles exhibited strong antibacterial activity against E. coli and S. aureus with a zone of inhibition (16 mm) and (14 mm) respectively. This high antibacterial and catalytic activity of biogenic ZnO nanoparticles can be attributed to its small size, good dispersion, and well-defined morphology.

Ali J ，Irshad R ，Li B ，Tahir K ，Ahmad A ，Shakeel M ，Khan NU ，Khan ZUH ... -  《-》