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Life generates cellular energy by linking electron donor oxidation to acceptor reduction. Each electron source and sink has an inherent potential which together defines the maximum amount of energy available when electrons are exchanged in coupled reactions. For example, the difference in NO − 3 and Fe(III)(oxyhydr)oxides reduction potentials is more than half a volt, representing an additional 60 kJ/mol e − available during nitrate reduction when acetate is the donor (E°′ of NO − 3 ∕NO − 2 = +0.43 V vs. E°′ of Fe(III) (oxyhydr)oxides/ Fe(II) ~−0.2 V vs. standard hydrogen electrode [SHE]) (Fischer, 1987;

Green chemistry approaches for designing therapeutically significant nanomedicine have gained considerable attention in the past decade. Herein, we report for the first time on anticancer potential of phytogenic platinum nanoparticles (PtNPs) and palladium nanoparticles (PdNPs) using a medicinal plant Gloriosa superba tuber extract (GSTE). The synthesis of the nanoparticles was completed within 5 hours at 100°C which was confirmed by development of dark brown and black colour for PtNPs and PdNPs, respectively, along with enhancement of the peak intensity in the UV-visible spectra. High-resolution transmission electron microscopy (HRTEM) showed that the monodispersed spherical nanoparticles were within a size range below 10 nm. Energy dispersive spectra (EDS) confirmed the elemental composition, while dynamic light scattering (DLS) helped to evaluate the hydrodynamic size of the particles. Anticancer activity against MCF-7 (human breast adenocarcinoma) cell lines was evaluated using MTT assay, flow cytometry, and confocal microscopy. PtNPs and PdNPs showed 49.65 ± 1.99% and 36.26 ± 0.91% of anticancer activity. Induction of apoptosis was most predominant in the underlying mechanism which was rationalized by externalization of phosphatidyl serine and membrane blebbing. These findings support the efficiency of phytogenic fabrication of nanoscale platinum and palladium drugs for management and therapy against breast cancer.

Rapid, eco-friendly, and cost-effective one-pot synthesis of copper nanoparticles is reported here using medicinal plants like Gnidia glauca and Plumbago zeylanica. Aqueous extracts of flower, leaf, and stem of G. glauca and leaves of P. zeylanica were prepared which could effectively reduce Cu2+ ions to CuNPs within 5 h at 100°C which were further characterized using UV-visible spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, dynamic light scattering, X-ray diffraction, and Fourier-transform infrared spectroscopy. Further, the CuNPs were checked for antidiabetic activity using porcine pancreatic α-amylase and α-glucosidase inhibition followed by evaluation of mechanism using circular dichroism spectroscopy. CuNPs were found to be predominantly spherical in nature with a diameter ranging from 1 to 5 nm. The phenolics and flavonoids in the extracts might play a critical role in the synthesis and stabilization process. Significant change in the peak at ∼1095 cm−1 corresponding to C-O-C bond in ether was observed. CuNPs could inhibit porcine pancreatic α-amylase up to 30% to 50%, while they exhibited a more significant inhibition of α-glucosidase from 70% to 88%. The mechanism of enzyme inhibition was attributed due to the conformational change owing to drastic alteration of secondary structure by CuNPs. This is the first study of its kind that provides a strong scientific rationale that phytogenic CuNPs synthesized using G. glauca and P. zeylanica can be considered to develop candidate antidiabetic nanomedicine.

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This report details on synthesis of AuNPs and AgNPs using POLE with optimized reaction parameters, for the first time. The bioreduced nanoparticles were characterized using UV-visible spectroscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), dynamic light scattering (DLS), X-ray diffraction spectroscopy (XRD), fourier transform infrared (FTIR) spectrometry. Both AuNPs and AgNPs Further we evaluated the catalytic potential of the nanoparticles towards reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using NaBH 4 . AbstractIn an attempt to synthesize novel catalytic gold (AuNPs) and silver nanoparticles (AgNPs) we have used Platanus orientalis leaf extract for both reduction and capping. The synthesis was rapid which completed by 5 h as indicated by change in colour and development of prominent peak at 540 nm for AuNPs and 440 nm for AgNPs, as revealed by UV-visible spectroscopy. The phytogenic nanoparticles showed exotic shapes which included triangles, spheres, hexagons and pentagons as analyzed by high resolution transmission electron microscopy. The optimized processing parameters like salt concentration (1 mM concentration of HAuCl 4 and 4 mM of AgNO 3 ) and the reaction temperature (50°C) led to faster nanoparticles synthesis. Energy dispersive spectra and X-ray diffraction studies confirmed the elemental gold and silver in AuNPs and AgNPs. Detailed phytochemical characterization using biochemical techniques and gas chromatography mass spectrometry indicated the predominance of ascorbic acid, citric acid, reducing sugars and even starch which may together lead to simultaneous synthesis and capping. Further, AuNPs and AgNPs catalyzed the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using NaBH 4 with apparent rate constants of 1.908 × 10 -4 min -1 and 3.071 × 10 -4 min -1 , respectively. Figure 1: UV-vis spectra recorded as a function of reaction time for nanoparticle synthesis using POLE at 40°C with (A) HAuCl 4 solution and (B) 1mM AgNO 3 solution.Figure 2: Time course of nanoparticle synthesis using POLE at different reaction temperatures with (A) 1 mM HAuCl 4 and (B) 1 mM AgNO 3 .Figure 10: UV-vis absorption spectra during the reduction of 4-nitrophenol as a function of chemocatalytic activity of (A) AuNPs and (B) AgNPs synthesized by POLE. Inset figures represent plot of ln (A t /A 0 ) versus time for the reduction of 4-NP.