Multi-spectroscopic and thermodynamic profiles on HSA binding of Cassia fistula leaf based potential antibacterial and anticancer silver nanoparticles.

Here, a simple, one step, lucrative and green synthesis of Cassia fistula leaf extract inspired antibacterial silver nanoparticles (CF-SNPs) was provided. Characterization of these CF-SNPs were achieved by using various spectroscopic techniques for instance Ultraviolet Visible (UV-Vis) Spectroscopy, Fourier-Transform Infrared (FTIR) Spectroscopy, Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray (EDX). The effective antibacterial action of the CF-SNPs was checked against Escherichia coli (E. Coli) DH5-Alpha where MIC was 1.6 nM. Anticancer dynamism of the CF-SNPs was also tested in opposition to skin melanoma, A375 cell lines in which 4.4 nM was IC50. The binding proneness of HSA towards CF-SNPs was investigated by means of UV-Vis Spectroscopy, Fluorescence Spectroscopy, Time Resolved Fluorescence Spectroscopy, Circular Dichroism (CD) Spectroscopy, Dynamic Light Scattering, and Isothermal Titration Colorimetry (ITC). CD spectroscopy established minor secondary structural exchange of HSA in HSA-CF-SNPs complex. ITC and Time Resolved Fluorescence Spectroscopy verified the static type quenching mechanism involved in HSA-CF-SNPs complex. The binding constant was 3.45 × 108 M-1 at 298.15K from ITC study. The thermodynamic parameters showed that the interaction was occurred spontaneously by the hydrophilic forces and hydrogen bonding.Communicated by Ramaswamy H. Sarma.

Biophysical insights into the interaction of human serum albumin with Cassia fistula leaf extracts inspired biogenic potent antibacterial and anticancerous gold nanoparticles.

In the present investigation, the characterization of Cassia fistula leaf extracts (CFLE) mediated gold nanoparticles (CF-GNPs) and its binding features with human serum albumin (HSA) through interaction have been probed. The results from UV-visible, TEM and EDX analysis proved the formation of CF-GNPs. The functional groups like OH, NH, CN etc present in the phytochemicals of CFLE were mainly acted as reducing and protecting agent which was confirmed by FTIR study. The zeta potential (-17.8 mV) and hydrodynamic size (20.4 nm) of the CF-GNPs were also measured by DLS. The microbicidal effect of the CF-GNPs was estimated against gram negative bacterium, Escherichia coli (DH5-Alpha) and MIC was found to be 2.8 nM. Anticancer activity of the CF-GNPs was also checked against A375 (skin melanoma) cell lines where IC50 was 6.5 nM. The interaction study of CF-GNPs with HSA and conformational alteration of HSA upon interaction were investigated by the fluorescence, lifetime, synchronous, circular dichroism spectrum and zeta potential measurement. The negative value of Gibb's free energy indicated spontaneity of the CF-GNPs-HSA complex formation. The fluorescence lifetime measurement confirmed the construction of ground state CF-GNPs-HSA complex passing through static quenching mechanism and determined the distance from donor to acceptor also. Circular dichroism spectroscopy signified unchangeable native structure of HSA with minor decrease of alpha helix structure (54.5% to 51.1%) upon interaction. The more negative zeta potential value (-25.9 mV) of CF-GNPs-HSA system than the CF-GNPs (-17.8 mV) proved the adsorption of HSA on the outer surface of CF-GNPs.Communicated by Ramaswamy H. Sarma.

Carbon dots derived from lychee waste: Application for Fe3+ ions sensing in real water and multicolor cell imaging of skin melanoma cells.

Exploit of biomass as an inexhaustible resource has accepted much more curiosity to the present research world. Herein, a simple, one-step solvothermal action has been used to synthesize an ascendable amount of fluorescent carbon dots (CDs) with an average size of~3.13 nm, from Low-reasonable and green source lychee waste. The excitation/emission maxima of CDs have 365/443 nm with high quantum yield (23.5%). The present ingredient predominantly contained carboxylic acid and hydroxyl group that acted as a passive agent for stabilizing the CDs. The structural and optical properties were evaluated through HRTEM, FTIR, UV-vis, zeta potential, XPS, fluorescence, and fluorescence lifetime experiments. We investigated the manoeuvre of our synthesized CDs as a probe for detection of Fe3+ ions in water bodies; This sensing approach showed impressive selectivity and sensitivity towards Fe3+ions with LOD 23.6 nM. The sensing mechanism took place through static quenching which was entrenched through fluorescence lifetime measurements. Fe3+ ions detection was basically carried out with efficacy in real water. For its lofty Photo-stability, low cytotoxicity and cell viability the probe were substantially applied for bio-imaging experiment i.e. intracellular multi-color cell imaging in skin melanoma cells (A375 cells) with and without Fe3+ ions exemplifying its real applications in living cells.

Berberine derivatives as heteroatom induced hydrophobic sensor: An analytical approach for the selective and sensitive fluorometric detection and discrimination of serum albumins.

The detection and discrimination of serum albumins (SAs) has been transforming as a research work of keen interest to the scientists in recent times. This is in the root of foundation of more and more fluorescent probes to selectively identify and distinguish the SAs in the modern era of research. Fluorescence based sensors are preferably on high demand because of high sensitivity of fluorescence spectroscopy. Herein we have synthesized berberine derivatives with substitutions at two different positions (9 and 13) with the purpose of an analytical study to detect and differentiate the SAs. It was found that only the 9-O substituted derivatives showed a dramatic enhancement in their inherently weak fluorescence intensity after the addition of serum albumins (BSA and HSA) indicating the occurrence of heteroatom induced hydrophobic binding interaction. Lower value of detection limit, 6.8 nM and 6.1 nM for BSA and 17.8 nM and 16.3 nM for HSA respectively for the two compounds N1 and N2 and extended range of linearity for both the probes justify the fruitfulness of the research work. Moreover, the two effective 9-O substituted probes response differently in presence of the two SAs by the nature, intensity of the fluorescence spectra and position of wavelength maxima which enable us in deciphering the two essential proteins. All the results reveal how the presence of a heteroatom influences the hydrophobic sensing of the SAs and divulge the utility of the synthesized berberine derivatives in detection and distinction of two SAs successfully in the coming years.

Green synthesis of silver nanoparticles using Pongamia pinnata seed: Characterization, antibacterial property, and spectroscopic investigation of interaction with human serum albumin.

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 λmax  = 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 â”€ H, C â• 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 LD50 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.