Green and Chemical Syntheses of CdO NPs: A Comparative Study for Yield Attributes, Biological Characteristics, and Toxicity Concerns.

Metallic nanoparticles (NPs) have enormous applications due to their remarkable physical and chemical properties. The synthesis of NPs has been a matter of concern because chemical methods are toxic. On the contrary, biological methods are considered eco-friendly. To compare the toxicity and the environment-friendly nature of the synthesis methodologies, cadmium NPs were synthesized through chemical (Ch) (co-precipitation) and biological (plant extracts as reducing agent) methods. Cadmium nitrate was reduced with NaOH, while in the biological method, the Cd ions were reduced by Artemisia scoparia (As) and Cannabis sativa (Cs) extracts. X-ray diffraction (XRD) analysis confirmed the pure single-phase cubic structure of green and chemically synthesized CdO NPs except As-CdO NPs that were crystalline cum amorphous in nature. The size of nanoparticles was 84 nm (Cs-CdO NPs) and 42.2 nm (Ch-CdO NPs). The scanning electron microscope (SEM) images exhibited an irregular disklike morphology of nanoparticles that agglomerated more in the case of green synthesis. The antioxidant and antimicrobial potential of NPs revealed that chemically synthesized NPs have better antimicrobial capability, while the antioxidative activities were better for green-synthesized NPs. However, the low yield, high ion disassociation, and waste (unreacted metal) production in the green synthesis of CdO NPs increase the risk of contamination to biosphere. Both types of NPs did not affect the seed germination of Dodonaea viscosa. However, chemically synthesized NPs were less toxic on plant morphological response. The study concludes that the chemically synthesized CdO NPs have better morphology, significant antimicrobial activity, and less toxicity to plant species compared to green-synthesized NPs. Moreover, during the green synthesis, unreacted metals are drained, which causes contamination to the ecosystem.

Anticancer and antibacterial potential of Rhus punjabensis and CuO nanoparticles.

The present study reports ecofriendly synthesis of CuO nanoparticles (NPs) using an extract of Rhus punjabensis as a reducing agent. NPs structural and composition analysis are evaluated by X-rays diffraction (XRD), Fourier transform infrared, Energy dispersive spectroscopy, Scanning electron microscopy, Transmission electron microscopy, and Thermal analysis. The NPs have pure single phase monoclinic geometry with spherical structure and high stability toward heat and with average particle size of about 36.6 and 31.27 nm calculated by XRD and SEM, respectively. NPs are tested for antibacterial, protein kinase (PK) inhibition, SRB cytotoxic, and NF-κB activities. Antibacterial activity is observed against B. subtilis and E. coli. Significant PK and SRB cytotoxic activity is observed with some NF-κB inhibition. NPs IC50 values against HL-60 and PC-3 prostate cancer cells are 1.82 ± 1.22 and 19.25 ± 1.55 µg/mL. The results encourage further studies for antibacterial and anticancer drug development of NPs using animal models.

CeO2 nanoparticles synthesized through green chemistry are biocompatible: In vitro and in vivo assessment.

Widespread use of cerium oxide (CeO2 ) nanoparticles (NPs) is found in almost all areas of research due to their distinctive properties. CeO2 NPs synthesized via green chemistry have been characterized for antioxidant, phytochemical, and biological potential. Physical characterization through scanning electron microscopy, XRD, and TGA showed that the NPs are circular in shape, 20-25 nm in size, and stable in a wide range of temperature. NPs display significant antioxidant (32.7% free radical scavenging activity) and antileishmanial (IC50 48 µg mL-1 ) properties. In vitro toxicity tested against lymphocytes verified that NPs are biocompatible (99.38% viability of lymphocytes at 2.5 µg mL-1 ). In vivo toxicity experiments showed no harmful effects on rat serum chemistry and histology of various organs and did not even change the concentration of antioxidative enzymes, total protein contents, lipid peroxidation, and nitrosative stress. These observations are in line with the statement that plant-based synthesis of CeO2 NPs lessens or nullifies in vitro and in vivo toxicity and hence CeO2 NPs are regarded as a safe and biocompatible material to be used in drug delivery.

Kinnow peel extract as a reducing and capping agent for the fabrication of silver NPs and their biological applications.

An effective approach used for the synthesis of silver nanoparticles (AgNPs) through green chemistry by using Kinnow peel extract as a reducing and capping agent is presented. Two different approaches, diluted and concentrated peel extracts, were used for the synthesis of AgNPs. Ultraviolet-visible spectroscopy exhibits characteristic absorption peaks at 425 and 400 nm for nanoparticles (NPs) synthesised by diluted and concentrated extracts, respectively. The X-ray diffraction analysis of nanofabricated silver exhibited a pure face centred cubic structure of 27.4 and 18.1 nm sizes calculated by using Scherrer equation. Scanning electron microscopy analysis showed a uniform morphology of synthesised NPs. Significant antioxidant, phytochemical and antibacterial assays show that both AgNPs can be effectively used in biomedical applications. Furthermore, the use of citrus peel for the synthesis of NPs can be an effective tool in waste management.

Antimicrobial potential of green synthesized CeO2 nanoparticles from Olea europaea leaf extract.

This article reports the green fabrication of cerium oxide nanoparticles (CeO2 NPs) using Olea europaea leaf extract and their applications as effective antimicrobial agents. O. europaea leaf extract functions as a chelating agent for reduction of cerium nitrate. The resulting CeO2 NPs exhibit pure single-face cubic structure, which is examined by X-ray diffraction, with a uniform spherical shape and a mean size 24 nm observed through scanning electron microscopy and transmission electron microscopy. Ultraviolet-visible spectroscopy confirms the characteristic absorption peak of CeO2 NPs at 315 nm. Fourier transform infrared spectroscopy reflects stretching frequencies at 459 cm-1, showing utilization of natural components for the production of NPs. Thermal gravimetric analysis predicts the successful capping of CeO2 NPs by bioactive molecules present in the plant extract. The antimicrobial studies show significant zone of inhibition against bacterial and fungal strains. The higher activities shown by the green synthesized NPs than the plant extract lead to the conclusion that they can be effectively used in biomedical application. Furthermore, reduction of cerium salt by plant extract will reduce environmental impact over chemical synthesis.