Nontoxic silver nanocluster-induced folding, fibrillation, and aggregation of blood plasma proteins.

In recent years, concerns have been raised considering the potential risks of nanocluster (NC) for the environment and human health. Since the blood circulation system is probably the first entry route of NC into the human body, adsorption of blood proteins on NC may change cellular responses, including cellular uptake efficiency, bio distribution patterns, and nanotoxicity profiles, besides other biological effects. Therefore, the interaction of NCs with proteins and the cellular implications can be therapeutically of great importance. Adsorption of human blood proteins on NCs has been methodically investigated. In the present study, the first analysis of fibrillation was conducted between MBI-AgNCs and human serum (a complex biofluid). AgNCs were prepared by coating with 2-mercaptobenzimidazole. Then, interactions with human blood proteins, such as immunoglobulin, albumin, and insulin were investigated using various experimental approaches. Upon protein association, the fluorescence of proteins significantly decreased, accompanied by a blue shift in the AgNCs-human serum albumin (HSA) system and a red shift in the AgNCs-insulin/γ-globulin. Concomitantly, circular dichroism spectroscopy and atomic force microscopy were employed to investigate the effects of protein binding to NCs. We found that AgNCs induced γ-globulin aggregation. HSA at the AgNC surface was partially unfolded and could promote protein self-assembly into amyloid fibrils, while the surface morphology remained unchanged after insulin incubation. The atomic force microscopy (AFM) data and the ThT and CR analysis of the proteins, as well as circular dichroism (CD) and fluorescence findings, support the use of AgNCs as an indicator for monitoring the progress of HSA fibrillogenesis. Additionally, cytotoxicity assays were used to ensure the biocompatibility of nanoparticles within the applicable limits.

Design of green magneto-fluorescent γ-Fe2O3-methyldopa conjugate nanocrystal as a targeted probe for monitoring of esterase activity.

One of the most important aspects of the biological systems is the retention of HSA activity. It is known that serum albumin, in addition to ligand binding capabilities, possesses some enzymatic properties such as esterase activity with p-nitrophenyl acetate substrate. The aim of this study was to synthesize and characterize the mono-dispersed magneto-fluorescent methyldopa coated (MNPs-MDP) which provides a unique opportunity to control and monitor the biological interactions by using magnetic force. An Organic fluorophore methyldopa (2-amino-3-(3,4-dihydroxyphenyl)-2-methyl acid, propanoic) (MDP) was introduced into γ-Fe2O3 particles and made the fluorescent and stable colloidal nanocrystals. As a biological host, human serum albumin (HSA) was chosen which is a major constituent of soluble human blood plasma proteins and is therefore considered as a suitable target for nanoparticle-protein interaction studies. MDP-γ-Fe2O3 nanocrystals showed inherent properties including excellent water solubility, and longtime stability against aggregation, biocompatibility and multifunctional surface rich in carboxyl groups. In addition, we tried to assess the influence of PMDP-γ-Fe2O3 binding on the activity of HSA. Such MDP-γ-Fe2O3 showed an increase in esterase activity in comparison with the free HSA. This method therefore provides a unique platform for preserving the protein structure and conformation.

Multispectroscopic studies on the interaction of a platinum(II) complex containing L-histidine and 1,10-phenanthroline ligands with bovine serum albumin.

The mechanism of the interaction between bovine serum albumin (BSA) and [Pt(phen) (histidine)](+) complex was studied employing ultraviolet (UV) absorption, circular dichroism (CD), FT-IR, differential pulse voltammetry (DPV), and fluorescence spectral methods. Fluorescence data showed that the intrinsic fluorescence of BSA was strongly quenched by Pt(II) complex in terms of an untypical static quenching process. The corresponding number of binding sites (n) and binding constant (K b) of BSA and complex at 283, 298, and 310 K were calculated to be 0.61 × 10(6), 19 × 10(6), and 42 × 10(6) M(-1), respectively. The results showed that the increasing temperature improves the stability of the complex-BSA system, which results in a higher binding constant and the number of binding sites of the complex-BSA system. The positive ΔH and positive ΔS indicated that hydrophobic forces might play a major role in the binding between complex and BSA. Based on Forster's theory of non-radiation energy transfer, the binding distance (r) between the donor (BSA) and acceptor (Pt(II) complex) was evaluated. The results of CD, UV-vis, DPV, and FT-IR spectroscopy showed that the binding of Pt(II) complex to BSA induced conformational changes in BSA.

DNA interaction studies of a platinum(II) complex containing L-histidine and 1,10-phenanthroline ligands.

The aim of this study was developing coordination complexes that can be used as inorganic medicinal agents. The water soluble [Pt(phen)(His)]NO(3)·3H(2)O complex in which phen=1,10-phenantheroline and His=L-histidine was synthesized and characterized using physicochemical methods. Binding interaction of this complex with calf thymus (CT) DNA was investigated by emission, absorption, circular dichroism, and viscosity measurement techniques. Upon addition of CT-DNA, changes were observed in the characteristic ultraviolet-visible (UV-Vis) bands (hypochromism) of the complex. The complex binds to CT-DNA in an intercalative mode. The calculated binding constant, K(b), was 8 ± 0.2 × 10(4) M(-1). In addition, circular dichroism (CD) study showed that the phenanthroline ligand was inserted between the base pair stack of the double-helical structure of DNA. Also, the fluorescence spectral characteristics showed an increase in fluorescence intensity of the platinum complex in the presence of increasing amounts of DNA solution. The experimental results showed that the platinum complex binds to DNA via intercalative and hydrogen bonding mode.

Expansion of CD4+ CD25+ FoxP3+ regulatory T cells in chronic hepatitis C virus infection.

BACKGROUND: Regulatory T cells (Tregs) have been involved in impaired immunity and may have a pivotal role in persistence of viral infections. OBJECTIVE: To develop a simple and reliable in-house three color flow cytometery of peripheral blood to understand the role of HCV infection in the increase of Tregs. METHODS: The level of naturally occurring CD4+ CD25+ FoxP3+ regulatory T cells (nTregs) in 20 chronically infected with hepatitis C virus (HCV) patients was compared to those of 15 healthy individuals by flowcytometry. In a different approach we performed permeabilization and intracellular staining before surface staining which allows the preservation of the surface molecules in the combined detection process and results in the normal frequency of nTregs in blood. RESULTS: Using the optimized method, it was shown that a significantly higher proportion of nTregs in the total CD4+ T cell population was seen in the peripheral blood of chronic HCV patients (0.83 ± 0.21%, p=0.05) as compared to controls (0.26 ± 0.1, p=0.05). CONCLUSIONS: In accordance with other studies, we showed that HCV infection induces a dramatic increase in Tregs, which might contribute to the immune response failure during HCV infection.

Incidence of end-stage renal disease in Guilan Province, Iran, 2005 to 2007.

We reviewed records of patients with ESRD in all dialysis and kidney transplant centers of Guilan province to determine the incidence and modalities for treatment of ESRD from 2005 to 2007. Records of 759 patients were reviewed during the 3-year period of the study. The male-female ratio was 1.34:1 and the men age at the time of diagnosis was 56.3 +/- 16.8 years. The most frequent age group was 60 years and older (45.8%). The incidence ESRD during 2005, 2006, and 2007 were 100.36 pmp, 100.60 pmp, and 110.66 pmp, respectively. The most common causes of ESRD were hypertension (29.4%), unknown (26.6%), and diabetes mellitus (17.9%). The most common modality at initiation of renal replacement therapy was hemodialysis (96.0%). The entrance rate of hemodialysis in 2005, 2006, and 2007 were 29.6%, 35.0%, and 35.4%, and the discontinuing rate of hemodialysis in these years were 29.5%, 32.1%, and 38.4%, respectively.