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This study describes the eco-friendly, low-cost and room-temperature synthesis of gold nanoparticles from Musa balbisiana leaf extract, which acts as both reducing and stabilizing agent, and characterized by ultraviolet-visible (UV-vis) light spectroscopy, fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM), analytical transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDAX) and dynamic light scattering (DLS) instruments. These nanoparticles showed an average diameter of 33.83 ± 3.39 nm, which was confirmed from the size distribution histogram. The bactericidal activity of these nanoparticles was confirmed using bacteria Escherichia coli and Staphylococcus aureus at 1 and 2 nM minimum inhibitory concentrations, respectively. The interaction between nanoparticles and human serum albumin (HSA) was investigated, as this plays significant roles in biological systems. The nature of interaction, binding parameters and structural variation of HSA in the presence of these nanoparticles have been evaluated using several useful spectroscopic approaches such as UV-vis, FTIR, time-resolved and steady-state fluorescence, and circular dichroism in addition to the measurement of zeta potential. This interaction study revealed that static quenching occurs in this process with minimal alteration in the secondary structure, but the native structure of HSA remained unaltered. The binding constant and thermodynamic parameters of this interaction process were also evaluated., (© 2019 John Wiley & Sons, Ltd.)

Nanomaterials in different form have been thoroughly used in the area of pharmaceutics and medicine for drug delivery. The large scale of nanoparticles (NPs) synthesis from plant extract is much safe, cheap and eco-friendly. Here, we demonstrated a new, one-step, ultra-fast biosynthesis of gold nanoparticles (sc-AuNPs, 19.54   nm) by using aqueous Spathodea campanulata leaf extracts as a reducing and capping agent. And also, we presented the synthesis of citrate capped gold nanoparticles (cit-AuNPs) of approximately same size (19.66 nm). These two NPs were characterized by UV-Visible, dynamic light scattering, transmission electron microscope and energy dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy confirmed that the functional groups like OH, NH, OH of COOH and CO were contributed in the sc-AuNPs formation. The negative zeta potential (-20.5, -22.8 mV) established the stability and dispersion of the sc- and cit-AuNPs. The anti-bacterial activity of the sc- and cit-AuNPs were checked against Escherichia coli (DH5-Alpha). Minimum inhibitory concentration was 2.4 and 3.0 nM, respectively for sc- and cit-AuNPs. The interaction study of the sc-AuNPs/cit-AuNPs-human serum albumin (HSA) system was done by UV-Visible absorbance, fluorescence, circular dichroism, time resolved fluorescence spectroscopy and the measurement of zeta potential. Absorbance, three dimensional fluorescence, synchronous fluorescence and circular dichroism spectroscopy showed a minor conformational change of HSA upon interaction with the sc-AuNPs compared to cit-AuNPs. The present comparative study will advance our knowledge about the binding mode, mechanism and conformational change of the protein upon interaction with green synthesized sc-AuNPs and cit-AuNPs. Communicated by Ramaswamy H. Sarma.

The green synthesis of nanoparticles has received increasing attention due to the growing demand to produce safe, cost-effective, and eco-friendly technology for nanomaterials synthesis. We report on the use of aqueous Croton bonplandianum (Family: Euphorbiaceae, Genus: Croton) leaves extract for the preparation of silver nanoparticles (AgNPs) without using any external reducing and stabilizing agent. Ultraviolet-visible spectroscopy showed maximum absorbance at 446 nm due to surface plasmon resonance of AgNPs. Energy dispersive X-ray spectra also supported the existence of AgNPs. An average diameter (d = ~17.4 nm) of the spherical AgNPs was determined from the transmission electron microscopic images. Hydrodynamic size (d = ~21.1 nm) was determined by dynamic light scattering. Fourier transform infrared analysis designed that the functional groups like O-H, N-H, [Formula: see text], CONH 2 , and COOH participated in the AgNPs formation. The negative zeta potential value (-19.3 mV) of the AgNPs indicated its dispersion and stability. The AgNPs exhibited strong antibacterial activity against Escherichia coli ATCC 25922 and 1.5 nM proved to be minimum inhibitory concentration for it. Hemolysis assay demonstrated the blood compatibility of the AgNPs toward human RBCs. The binding affinity of the AgNPs toward human hemoglobin and human serum albumin (HSA) was also determined by means of fluorescence spectroscopy. The circular dichroism spectroscopy revealed that the native structures of human hemoglobin and HSA remain unchanged, but its secondary structures were slightly changed upon interaction with AgNPs. Overall, it can be concluded that the AgNPs may be applied in the area of nanomedicines.

In recent years, green synthesized nanoparticles from plant extract have drawn a great interest due to their prospective nanomedicinal application. This study investigates a proficient, safer, and sustainable way for the preparation of AgNPs using medicinal plant Pongamia pinnata (family: Leguminoseae, species: Pinnata) seeds extract without using any external reducing and stabilizing agent. Both ultraviolet-visible spectrum at λ max  = 439 nm and energy dispersive X-ray spectra proof the formation of AgNPs. An average diameter of the AgNPs was 16.4 nm as revealed from transmission electron microscope. Hydrodynamic size (d = ~19.6 nm) was determined by dynamic light scattering (DLS). Zeta potential of AgNPs was found to be -23.7 mV, which supports its dispersion and stability. Fourier transform infrared study revealed that the O ─ H, C ═ O, and C-O-C groups were responsible for the formation of AgNPs. The antibacterial activity of the synthesized AgNPs was checked against Escherichia coli ATCC 25922. AgNPs at its LD 50 dose exhibited synergistic effect with ampicillin. Because protein-AgNPs association greatly affects its adsorption, distribution, and functionality and can also influence the functions of biomolecules. So in order to understand the adsorption and bioavailability, we investigated by fluorescence, ultraviolet-visible, and circular dichroism spectroscopic methods the interaction of synthesized AgNPs toward human serum albumin. The binding affinity and binding sites of human serum albumin toward AgNPs were measured by using the fluorescence quenching data. The circular dichroism spectroscopic results revealed that there was a negligible change of α-helical content in their native structure. Overall, these AgNPs show versatile biological activities and may be applied in the field of nanomedicine., (Copyright © 2016 John Wiley & Sons, Ltd.)

Abstract We have reported the eco-friendly gold nanoparticles (AuNPs) from 15% aqueous leaf extract of therapeutic plant Nymphaea nouchali where leaf extract acts as both reducing and stabilizing agents. The generation of AuNPs was confirmed by UV–visible spectroscopy, FTIR, FE-SEM, DLS, and the size and morphology were further confirmed via TEM analysis (average d = 54.7 nm). The existence of gold signal in EDX spectrum and measurement of zeta potential reveals a negative value (−21.7 mV) clearly indicates its stability. This synthesized AuNPs shows strong in vitro bactericidal effect against E. coli (DH5-Alpha) with 0.12 nM minimum inhibitory concentration, suggests its progress in therapeutic efficacy. The interaction of this AuNPs with human serum albumin (HSA) was investigated by UV–visible, FTIR, fluorescence, circular dichroism spectroscopies and zeta potential evaluation at 25 °C. It has been observed that the interaction mechanism is a static quenching process with the slightest change in the HSA secondary conformation because of HSA-AuNPs conjugate formation, but the primary structure remains unaffected. Negative free energy change indicates, the HSA-AuNPs formation is a thermodynamically favourable process. This analysis may offer a valuable information on the healthier antibacterial AuNPs synthesized from a medicinal plant extract. Graphical abstract Image 1 Highlights • AuNPs was eco-friendly synthesized by Nymphaea nouchali (Lily) leaf extract. • Average diameter of AuNPs (54.7 nm) was evaluated from TEM micrographs. • Strong bactericidal effect of AuNPs on E. coli (DH5-Alpha) was established. • Interaction of HSA with AuNPs was investigated spectroscopically with mechanism. • Free energy, fluorescence quenching and binding constants of HSA-AuNPs was evaluated. [ABSTRACT FROM AUTHOR]

Nanomaterials are used to modify and improve the pharmacodynamic and pharmacokinetic properties of drug molecules of diverse types. The plant extracts are safe, beneficial and ecological for the synthesis of the large scale of nanomaterials. Herein, we report the new ultra fast silver nanoparticles (SNPs) synthesis via green route using aqueous Spathodea campanulata leaf extracts without using any external reducing ̸ stabilizing agent and assessment of their bio-logical application. The maximum UV–Vis spectroscopic absorbance was observed at 438 nm. EDX spectra also confirmed the construction of SNPs. TEM analysis revealed that the biogenic SNPs were of 18.4 nm in size ( d ). Hydrodynamic size ( d = ~20 nm) was deliberated by the DLS. FT-IR study indicated that OH, NH, N-O, CO and COOH functional groups participated in the construction of SNPs. The zeta potential value (−16.8 mV) confirmed the dispersion and stability of the SNPs. The SNPs showed a dose dependent bactericidal property against Escherichia coli ATCC 25922 and MIC was found to be 1.2 nM for it. The binding of SNPs with human serum albumin (HSA) and SNPs-HSA complex were investigated by UV–Vis absorbance, fluorescence, circular dichroism (CD) spectroscopy, fluorescence lifetime and zeta potential measurement. The slight conformational changes of the protein in the presence of SNPs were confirmed by absorbance, 3D fluorescence, synchronous fluorescence and CD spectroscopy. This work improves our knowledge about the structural nature of binding between the biogenic SNPs and HSA. [ABSTRACT FROM AUTHOR]

This study investigates the green synthesis of AgNPs from 1 mM aqueous AgNO 3 using 10% leaf extract of Alstonia scholaris (Chhatim) for its wide antibacterial and medicinal properties. The synthesized AgNPs were duly characterized by UV–vis (UV–vis) spectrophotometry, dynamic light scattering, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive analysis of X-rays spectroscopy, and fourier transform infrared spectrophotometry. Their antibacterial property was tested against Escherichia coli (ATCC 25922), and minimum inhibitory concentrations of 0.08 nM of AgNPs were obtained, which suggests improved therapeutic efficacy. We report the interaction of human serum albumin (HSA) with this nanoparticle, and this interaction was studied by UV–vis, fluorescence, and circular dichroism spectroscopies and zeta potential measurement at room temperature. It was found that the AgNPs form a complex with HSA, which may cause the slightest change in the conformation of HSA. The calculated values of Stern-Volmer quenching constant, binding constant, and binding distance were 1.82 × 10 7 M −1 , 1.58 × 10 7 M −1 , and 3.68 nm, respectively. Therefore, in future, the present study may provide useful information to design a better antibacterial compound by using green synthesized nanoparticles with fewer side effects. [ABSTRACT FROM AUTHOR]

This study looks into a safe, proficient and low-cost way for the preparation of novel silver nanoparticles by using 5% aqueous leaves extract of a medicinal plant, Marsilea quadrifolia (family: Marsileaceae ) without using any external reducing and stabilizing agents. The synthesized AgNPs showed maximum UV–Vis absorbance at 435 nm due to surface plasmon resonance (SPR). The average diameter (∼22.5 nm) of AgNPs was measured from TEM analysis and was also supported by FE-SEM. The existence of a silver signal in EDX spectra supported the AgNPs formation and negative zeta potential value (−18.7 mV) which suggested its stability. FT-IR spectroscopic analysis showed that the functional groups like O H, N H and C O were responsible for the synthesis of AgNPs. The antibacterial activity of the AgNPs was tested against E. coli ATCC 25922. The anticancer potential of AgNPs was also assessed using two different cell lines, such as MCF-7 and HeLa. The interaction study of AgNPs with human serum albumin (HSA) and human hemoglobin (Hb) was performed by means of UV–Vis, fluorescence spectroscopy, Circular dichroism (CD) and zeta potential measurement. More negative zeta potential values of AgNPs-HSA/Hb (−21.1/-19.5 mV) complexes than AgNPs (−18.7 mV) indicated corresponding stability of bio-conjugates. The basic structure of HSA/Hb remained unchanged and its secondary structure was slightly changed upon interaction with the AgNPs concluded from Circular dichroism. So, it can be predicted that this AgNPs may be applied in the medical field. [ABSTRACT FROM AUTHOR]