Selvaraj Naveenraj

The interaction of sonochemically synthesized gold nanoparticles with serum albumins

Spherical gold nanoparticles of approximately 16nm were synthesized using a sonochemical reduction method and characterized using UV-vis spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The binding of these gold nanoparticles with bovine serum albumin (BSA) and human serum albumin (HSA) was investigated using UV-vis absorption and fluorescence spectroscopic techniques. A strong quenching of the fluorescence from serum albumins was observed due to the formation of a ground state complex with gold nanoparticles (static quenching). The fluorescence quenching constants, number of binding sites and binding constants were determined using Stern-Volmer and Benesi-Hildebrand plots. Using Forster Resonance Energy Transfer (FRET) theory, the distance between the donor (serum albumins) and acceptor (gold nanoparticles) was obtained, which showed that HSA has more affinity towards sonochemically synthesized gold nanoparticles compared to gold nanoparticles synthesized using other methods.

Insights into the binding of photothermal therapeutic agent bismuth sulfide nanorods with human serum albumin

The biomedical application of bismuth sulfide (Bi2S3) nanorods as a nanomedicine for the photothermal therapy of tumors prompted this study into their interactions with human serum albumin (HSA) to understand their pharmacokinetics. Bi2S3 nanorods with orthorhombic crystalline structure were synthesized using a simple microwave irradiation method from bismuth nitrate, sodium sulfide, and starch in an aqueous medium. The synthesized Bi2S3 nanorods and their formation mechanism were well-characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy-dispersive X-ray (EDX). The interactions of the Bi2S3 nanorods with HSA was investigated by absorption spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. The absorption and time-resolved fluorescence spectroscopy studies confirmed that the Bi2S3 nanorods interacted with HSA through a static mechanism. The steady-state and synchronous fluorescence spectral studies showed that the single binding site is near the tryptophan moiety (Trp-214) in HSA. The moderate binding constant determined from the steady-state fluorescence study suggested the possibility of effective transportation of Bi2S3 nanorods inside the body. These results could be very helpful for understanding the mechanisms and pathways responsible for the uptake, distribution and catabolism of Bi2S3 nanorods in multiple tissues of the human body.

A multispectroscopic and molecular docking investigation of the binding interaction between serum albumins and acid orange dye

The interaction of Acid Orange 10 (AO10) with bovine serum albumin (BSA) was investigated comparatively with that of human serum albumin (HSA) using multispectroscopic techniques for understanding their toxic mechanism. Further, density functional theory calculations and docking studies have been carried out to gain more insights into the nature of interactions existing between AO10 and serum albumins. The fluorescence results suggest that AO10 quenched the fluorescence of BSA through the combination of static and dynamic quenching mechanism. The same trend was followed in the interaction of AO10 with HSA. In addition to the type of quenching mechanism, the fluorescence spectroscopic results suggest that the binding occurs near the tryptophan moiety of serum albumins and the binding. AO10 has more binding affinity towards BSA than HSA. An AO10-Trp model has been created to explicitly understand the CHπ interactions from Baders quantum theory of atoms in molecules analysis which confirmed that AO10 bind more strongly with BSA than that of HSA due to the formation of three hydrogen bonds with BSA whereas it forms two hydrogen bonds in the case of HSA. These obtained results provide an in-depth understanding of the interaction of the acid azo dye AO10 with serum albumins. This interaction study provides insights into the underlying reasons for toxicity of AO10 relevant to understand its effect on bovids and humans during the blood transportation process.

A general microwave synthesis of metal (Ni, Cu, Zn) selenide nanoparticles and their competitive interaction with human serum albumin

A series of selenide nanoparticles (3 ± 1 nm sized platelet-like NiSe nanoparticles, uniform CuSe nanorods with a width of ∼12 nm and a length of 65 nm, and distorted ZnSe nano-hexagons with a side length of 12 ± 3.5 nm) were synthesized using a simple microwave irradiation technique using sodium selenite, hydrazine hydrate and starch as a selenide precursor, a reducing agent and a stabilizing agent, respectively. The morphologies and sizes of the as-synthesized nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. The interaction between this series of selenide nanoparticles (SNPs) and HSA was investigated using fluorescence and circular dichroism (CD) spectroscopy. The influencing factors such as the quenching type, binding stoichiometries, binding constants, and the free energy change determined using the fluorescence technique showed that SNPs spontaneously bound to HSA in a 1 : 1 ratio through non-fluorescent ground-state complex formation (static quenching mechanism). The binding constant values indicated that the binding forces were in descending order of NiSe > CuSe > ZnSe. The shift in the synchronous fluorescence spectra signified the involvement of the tryptophan moiety in the binding of SNPs with HSA. Based on the Forster theory of energy transfer, the distance between the donor (Trp residues) and the acceptor (SNPs) was obtained. Analysis of the far-UV and near-UV CD spectra of HSA suggested the effect of the SNPs on the secondary and tertiary structures of HSA. These investigations helped us to understand the interaction mechanisms between the nanoparticles and the protein molecule that interprets the pharmacokinetics of these nanoparticles while administering them as drugs.