Biophysical study of cisplatin loaded albumin-gold nanoparticle and its interaction with glycans of gp60 receptor.

The biophysical study provides a quantitative understanding of biomolecular interaction. The interaction of protein-nanoparticle has been critically examined using various biophysical and biochemical tools. The present investigation focussed on the biophysical characterization of anticancer drug cisplatin (CPT) with Bovine Serum Albumin (BSA) - Gold nanoparticles (GNP) conjugate; and BSA-CPT-GNP interaction with glycan sugars of glycoprotein receptor. Spectroscopic study (UV visible and fluorescence) showed strong binding of CPT loaded BSA with GNP. The binding between BSA-CPT-GNP and glycan sugars of gp60 receptor was estimated. Circular Dichroism (CD) spectroscopy study revealed weak alteration in the secondary structure of BSA upon CPT and GNP binding. Dynamic Light Scattering (DLS) data indicated the changes in the size of conjugates; zeta potential data showed the stability of conjugates. Biocompatible studies showed no toxicity to RBCs and chorioallantoic membrane (CAM). The mechanisms of interaction have been explored at the molecular and cellular levels. This investigation can be effectively extrapolated for in-vivo and in-vitro targeted drug delivery studies for cancer therapy.

BSA-drug-ZnO-PEI conjugates interaction with glycans of gp60 endothelial cell receptor protein for targeted drug delivery: a comprehensive spectroscopic study.

The zinc oxide (ZnO) nanoparticles (NPs) have several biomedical applications such as drug delivery, bio-imaging, and biomedical research. ZnO NPs were remedied with polyethyleneimine (PEI) and modified with bovine serum albumin (BSA). Two anticancer drugs - Cisplatin (CIS) and Gemcitabine (GEM) were used in conjugation with BSA. BSA-ZnO-PEI (conjugate 1), BSA-CIS-ZnO-PEI (conjugate 2), and BSA-GEM-ZnO-PEI (conjugate 3) can be used for targeted drug delivery via glycans - N-acetylneuraminic acid (NANA), L-fucose (FUC), N-acetyl glucosamine (NAG), D-mannose (MAN), and D-galactose (GAL), of albumin binding membrane receptor protein (gp60). Considerable interaction and the strong binding of conjugate 2 and conjugate 3 with NANA were observed by UV-visible absorption and fluorescence spectra. The electrostatic stability of conjugate 2 and conjugate 3 with NANA was considerably increased in comparison to conjugate 1 as evident with zeta potential values. The fluorescence quenching data (Ksv and kq) and binding parameters (K and n) of BSA-CIS, BSA-GEM, conjugate 2, and conjugate 3 with NANA and FUC attributes to the strong binding. Amide I and amide III bands of the Raman signal suggested insignificant loss in alpha-helical and beta-sheet content of conjugate 2 and conjugate 3 with NANA and FUC. Therefore, the present study is going to assist in the comprehensive development of conjugates for targeted drug delivery based on the differential glycation pattern of gp60 protein.Communicated by Ramaswamy H. Sarma.

Biophysical interactions between silver nanoparticle-albumin interface and curcumin.

Active targeted drug delivery methods facilitate effective uptake of functionalized nanoparticles through receptor-mediated transcytosis. In recent years, albumin-nanoparticle interaction has been critically examined so that this functionalized nanoparticle can be efficiently loaded with drugs. The present investigation aims at understanding the adsorption of Bovine Serum Albumin (BSA) on Silver Nanoparticle (SNP) surface, preparation of soft conjugates (SC) and hard conjugates (HC) of BSA-functionalized SNP (SNP-BSA), and their interaction with curcumin (CUR). HC contains tightly bound BSA whereas SC involves tightly and loosely bound BSA. Increase in the hydrodynamic radii of conjugates was observed upon SNP incubation with increased concentration of BSA. Three different SNP-BSA conjugate ratios were selected to study their interaction with CUR. Fluorescence spectroscopy showed a strong association between CUR and SNP:BSA conjugates. However, binding varied with a change in the conjugate ratio. Circular Dichroism (CD)/Fourier Transform Infrared (FTIR) spectroscopy revealed the alterations in the secondary structure of BSA upon CUR binding to the conjugates. Zeta potential data indicated stable conjugate formation. CUR in SNP:BSA conjugate was found to have a higher half-life as compared to the control. We believe that this is the first biophysical characterization report of conjugates that can be effectively extrapolated for targeted drug delivery.

Effect of Smartphone Light Fluxes on Cornea: A Biophysical Study.

OBJECTIVE: Biophysical study to investigate (a) the effects of smartphone light fluxes (SPLF) on isolated mammalian cornea and model protein (insulin), (b) to predict the possible visual interference of SPLF. MATERIALS AND METHODS: Fresh goat cornea and insulin protein were used as an experimental model system. The energy of absorbed SPLF was measured using chemical dosimeter. The effect of SPLF on the aggregation of model protein was studied using fluorescence spectroscopy and dynamic light scattering (DLS). Fluorescence microscopy, scanning electron microscopy (SEM), DLS, were used for cornea imaging. RESULTS: The spectral emission peak of SPLF was observed at 380 nm and 420 nm. Absorbed radiation of SPLF was found to be 2.82 mWm-2 and 1.92 mWm-2 for collimated (focussed) and noncollimated (nonfocussed) condition, respectively. Secondary structural changes of insulin were observed by fluorescence and zeta potential after SPLF exposure. SEM study revealed the disorganization of the epithelial cell surface, increase in intercellular space, disorganization of primary epithelium layer, and exposure of the second layer is seen in depth. Differential Interference Microscopy showed an optical gradient in images that appears to be changed in specimen structure. Fluorescence microscopy showed disorganization in epithelial cell pattern. A significant difference in bio-molecular permeation was observed in the exposed cornea. Ultraviolet UV-visible spectroscopy study indicated a reduction in light transmission through the cornea. CONCLUSIONS: The obtained results indicate changes in physicochemical and morphological modifications in the cornea and insulin modifications after exposed to SPLF.

Biophysical interactions between silver nanoparticle-albumin interface and curcumin / 药物分析学报

Active targeted drug delivery methods facilitate effective uptake of functionalized nanoparticles through receptor-mediated transcytosis. In recent years, albumin-nanoparticle interaction has been critically examined so that this functionalized nanoparticle can be efficiently loaded with drugs. The present investigation aims at understanding the adsorption of Bovine Serum Albumin (BSA) on Silver Nano-particle (SNP) surface, preparation of soft conjugates (SC) and hard conjugates (HC) of BSA-functionalized SNP (SNP-BSA), and their interaction with curcumin (CUR). HC contains tightly bound BSA whereas SC involves tightly and loosely bound BSA. Increase in the hydrodynamic radii of conjugates was observed upon SNP incubation with increased concentration of BSA. Three different SNP-BSA conjugate ratios were selected to study their interaction with CUR. Fluorescence spectroscopy showed a strong association between CUR and SNP:BSA conjugates. However, binding varied with a change in the conjugate ratio. Circular Dichroism (CD)/Fourier Transform Infrared (FTIR) spectroscopy revealed the alterations in the secondary structure of BSA upon CUR binding to the conjugates. Zeta potential data indicated stable conjugate formation. CUR in SNP:BSA conjugate was found to have a higher half-life as compared to the control. We believe that this is the first biophysical characterization report of conjugates that can be effectively extrapolated for targeted drug delivery.

Albumin nanoparticles conjugates binding with glycan - A strategic approach for targeted drug delivery.

Understanding the transcytosis phenomenon through albumin binding receptor (glycoproteins) is an important step towards targeted drug delivery research. The transcytosis of bovine serum albumin (BSA) occurs through its uptake by binding to glycoprotein (gp60) present on the endothelial cell membrane. gp60 possess abundant glycans like N-acetylneuraminic acid (sialic acid, NANA), l-fucose (FUC), N-acetyl glucosamine (NAG), d-mannose (MAN) and d-galactose (GAL). Hence, the objective of the present study was to insight the binding between BSA-gold nanoparticles (GNPs) and BSA-silver nanoparticles (SNPs) conjugates with model glycans using several biophysical techniques. The fluorescence spectroscopy analysis established the strong affinity of BSA-NPs conjugates with glycan's as observed with the bimolecular quenching rate, the Stern-Volmer constant (Ksv), binding constant and binding site. The increase in hydrodynamic radii of conjugates exhibited strong association and zeta potential confirmed the significant stability of conjugates. Circular dichroism (CD) study showed that the substantial amount of secondary structure (α-helix) was retained in NPs bound BSA while interacting with glycans. Raman spectroscopy study of BSA-GNP and BSA-SNP with glycans depicted the intrusion in the spectral range of 400-1800 cm-1. The overall results showed that BSA-NPs conjugates can act as a virtuous system for targeted drug delivery in endothelial cells.

Elucidation of structural and functional properties of albumin bound to gold nanoparticles.

Nanoparticle-albumin complexes are being designed for targeted drug delivery and imaging. However, the changes in the functional properties of albumin due to adsorption on nanoparticles remain elusive. Thus, the objective of this work was to elucidate the structural and functional properties of human and bovine serum albumin bound to negatively charged gold nanoparticles (GNPs). Fluorescence data demonstrated static quenching of albumin by GNP with the quenching of buried as well as surface tryptophan in BSA. The binding process was enthalpy and entropy-driven in HSA and BSA, respectively. At lower concentrations of GNP there was a higher affinity for tryptophan, whereas at higher concentrations both tryptophan and tyrosine participated in the interaction. Synchronous fluorescence spectra revealed that the microenvironment of tryptophan in HSA turned more hydrophilic upon exposure to GNP. The α-helical content of albumin was unaltered by GNP. Approximately 37 and 23% reduction in specific activity of HSA and BSA was observed due to GNP binding. In presence of warfarin and ibuprofen the binding constants of albumin-GNP complexes were altered. A very interesting observation not reported so far is the retained antioxidant activity of albumin in presence of GNP i.e. we believe that GNPs did not bind to the free sulfhydryl groups of albumin. However enhanced levels of copper binding were observed. We have also highlighted the differential response in albumin due to gold and silver nanoparticles which could be attributed to differences in the charge of the nanoparticle.

Bioactivity of albumins bound to silver nanoparticles.

The last decade has witnessed a tremendous rise in the proposed applications of nanomaterials in the field of medicine due to their very attractive physiochemical properties and novel actions such as the ability to reach previously inaccessible targets such as brain. However biological activity of functional molecules bound to nanoparticles and its physiological consequences is still unclear and hence this area requires immediate attention. The functional properties of Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) bound to silver nanoparticles (~60 nm) have been studied under physiological environment. Esterase activity, binding of drugs (warfarin and ibuprofen), antioxidant activity and copper binding by albumins was evaluated. The catalytic efficiencies of HSA and BSA diminished upon binding to silver nanoparticles. Perturbation in binding of warfarin and ibuprofen, loss of free sulphydryls, antioxidant activity and enhancement of copper binding were observed in albumins bound to nanoparticles. These alterations in functional activity of nanoparticle bound albumins which will have important consequences should be taken into consideration while using nanoparticles for diagnostic and therapeutic purposes.

Comprehensive studies on the interaction of copper nanoparticles with bovine serum albumin using various spectroscopies.

Copper nanoparticles (NPs) of average size of ~7.5nm were synthesized by chemical reduction method. Fluorescence spectroscopy in synchronous and polarization modes were used to examine the nature of interaction between Cu NPs and bovine serum albumin (BSA) at different temperatures. Fluorescence quenching results suggest that Cu NPs interact with BSA molecule through static mechanism, as inferred from the quenching of BSA fluorophore. The calculated thermodynamic parameters (ΔG°, ΔH°, and ΔS°) hint that the binding process occurs spontaneously by involving hydrophobic forces. Synchronous fluorescence spectra reveal that the interaction of Cu NPs with BSA mostly changes the microenvironment of tryptophan and not of tyrosine residues. The formation of BSA-Cu NPs ground state complex was also confirmed from the resonant light scattering and fluorescence polarization spectra. Circular dichroism and Raman spectra indicate that α-helicity of the BSA decreases due to the interaction with Cu NPs. It was also found that Cu NPs are located in the close proximity of BSA molecule, which transfer energy efficiently from the excited state of BSA fluorophore to the Cu NPs.

Systematic investigation on the interaction of bovine serum albumin with ZnO nanoparticles using fluorescence spectroscopy.

Zinc oxide (ZnO) nanoparticles with average size of ~7.5nm were synthesized to investigate their interaction with bovine serum albumin (BSA) at different temperatures. Fluorescence quenching, synchronous and polarization spectroscopy along with UV-vis absorption, circular dichroism and resonance light scattering spectroscopy techniques were used to establish the interaction mechanism between ZnO and BSA. The obtained results confirmed that the ZnO nanoparticles (NPs) quench the fluorophore of BSA by forming ground state complex in the solution. The fluorescence quenching data was also used to determine binding sites and binding constants at different temperatures. The calculated thermodynamic parameters (ΔG°, ΔH°, and ΔS°) suggest that the binding process occurs spontaneously by involving hydrogen bond and van der Waals interactions. The synchronous fluorescence spectra reveal that the microenvironment close to both the tyrosine and tryptophan residues of BSA is perturbed and that the hydrophobicity of both the residues is increased in the presence of ZnO NPs. Resonance light scattering, circular dichroism, and fluorescence polarization spectra suggest the formation of BSA-ZnO complex and conformational changes in BSA. The calculated distance between the BSA and ZnO NPs suggests that the energy transfer from excited state of BSA to ZnO NPs occurs with high efficiency.

Study of interaction of silver nanoparticles with bovine serum albumin using fluorescence spectroscopy.

The interaction between silver nanoparticles (SNPs) and Bovine Serum Albumin (BSA) was investigated at physiological pH in an aqueous solution using fluorescence spectroscopy. The analysis of fluorescence spectrum and fluorescence intensity indicates that SNPs have a strong ability to quench the intrinsic fluorescence of BSA by both static and dynamic quenching mechanisms. Resonance light scattering (RLS) spectra indicated the formation of a complex between BSA and SNP. The number of binding sites 'n' and binding constants 'K' were determined at different temperatures based on fluorescence quenching. The thermodynamic parameters namely ∆H°, ∆G°, ∆S° were calculated at different temperatures and the results indicate that hydrophobic forces are predominant in the SNP-BSA complex. Negative ∆G° values imply that the binding process is spontaneous. Synchronous fluorescence spectra showed a blue shift which is indicative of increasing hydrophobicity.

Modification of radiosensitivity of chlorpromazine with biological metal ions in Thiobacillus ferrooxidans.

Effect of chlorpromazine with biological metal ions, viz. calcium, magnesium, zink and copper was studied on T. ferrooxidans cell system. Chlorpromazine, calcium and magnesium alone could produce radioprotection. Maximum radioprotection was exhibited by chlorpromazine at lower concentration while copper and zink offered radiosensitization. However, combination of chlorpromazine with all biological metal ions exhibited radiosensitization. Dose modifying factor by chlorpromazine at lower concentration (0.025 mM) was 0.754 while in combination with Ca2+, Mg2+, Cu2+ and Zn2+ was 1.08, 1.25, 1.37 and 1.389 respectively. The possible interaction between chlorpromazine and biological metal ions is discussed at cellular membrane level.