Titanium oxide nanoparticles fabrication,hemoglobin interaction,white blood cells cytotoxicity,and antibacterial studies

This study is focused on the fabrication and characterization of titanium oxide (TiO₂) NPs. Afterwards; the interaction of TiO₂ NPs with human hemoglobin (Hb) was investigated by FTIR spectroscopy, fluorescence spectroscopy, and molecular docking studies. Also, the cytotoxic effect of fabricated TiO₂ NPs against human white blood cells (WBCs) was considered by MTT assay. The antibacterial effect of synthesized NPs was examined on Pseudomonas aeruginosa (ATCC 27853); Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). TEM and DLS investigations showed that the synthesized TiO₂ NPs have a narrow nano-sized distribution. XRD pattern of the fabricated NPs exhibited that the TiO₂ NPs contain anatase phase. Similarity in amide I and II signal intensities showed that secondary structure of the adsorbed Hb is preserved. The intrinsic fluorescence study revealed that the fluorescence quenching of Hb was done by complex formation between Hb and TiO₂ NPs trough the hydrogen bond and van der Waals interactions. Synchronous fluorescence spectroscopy determined that interaction of TiO₂ NPs with Hb did not unfold the Hb structure in the vicinity of the Tyr and Trp residues. Molecular docking study depicted that Glu-95, Thr-134 and Tyr-140 are involved in the formation of hydrophilic bonds. MTT data and antibacterial assays indicated that TiO₂ NPs endow distinguished antibacterial activities against Gram-negative and Gram positive strains at safe concentrations. This study may reveal that fabricated TiO₂ NP can be used as a safe and potent antibacterial agent.

Communicated by Ramaswamy H. Sarma     

Human serum albumin–malathion complex study in the presence of silver nanoparticles at different sizes by multi spectroscopic techniques

The binding of malathion to human serum albumin (HSA) in the presence of silver nanoparticles (AgNPs) was investigated for the first time by multiple spectroscopic methods such as fluorescence quenching, fluorescence resonance energy transfer (FRET), circular dichroism, red-edge excitation shift (REES), synchronous fluorescence and three dimensional fluorescence spectroscopy under physiological conditions .The results indicated that binding of malathion to HSA induced fluorescence quenching through static mechanism. The number of binding sites was calculated by double logarithmic equation. Changes in the micro-environment of the fluorophore residues were also probed by synchronous fluorescence spectroscopy and REES. Changes of secondary structure of HSA in HSA–malathion complex was verified by circular dichroism approach in the presence of AgNPs that showed the electrostatic interaction changes in the protein structure. The binding average distance (r) between the donor (HSA) and the acceptor (malathion) was measured and found to be 1.63?nm according to the Forster’s theory of non-radiation energy transfer which was <7?nm confirmed the existence of static quenching in the presence of AgNPs. The conformational changes of HSA by three-dimensional fluorescence spectroscopy were studied. By comparing the resonance light scattering in the binary and ternary systems, we could estimate the effect of AgNPs on the precipitation of the malathion on the HSA. Generally we have discussed the toxicity reduction effect of malathion in food industrial by the results of spectroscopy techniques.     

Association mapping of loci linked to copper,phosphorus, and potassium concentrations in the seeds of C. arietinum and C. reticulatum

Due to its high nutritional value, chickpea is one of the most important and cost-effective legumes for human diet. Nutrient elements, such as Cu, P, K have numerous essential functions for the human metabolism. In this study, association mapping of loci linked to the seed Cu, P and K concentrations were performed on a population consisting of 107 Cicer reticulatum and 73 Cicer arietinum individuals in four environments (two locations x two years). A total of 121,840 SNPs were genotyped across 180 individuals by GBS analysis. The association mapping between the SNP markers and the seed Cu, P, K concentrations were identified and eight SNPs were found to be significantly associated with variations in three nutrient elements in more than two environments This research suggests that association mapping is a useful methodology for the identification of loci controlling the Cu, P and K uptake in chickpea seeds for further association mapping, molecular breeding, and marker-assisted selection and plant breeding studies and provides a broader understanding of the relationship between the investigated Cicer species and the effects of environmental conditions.     

Biofilm inhibition and anti-quorum sensing activity of phytosynthesized silver nanoparticles against the nosocomial pathogen Pseudomonas aeruginosa

Quorum sensing (QS), the communication signaling network, regulates biofilm formation and several virulence factors in Pseudomonas aeruginosa PAO1, a nosocomial opportunistic pathogen. QS is considered to be a challenging target for compounds antagonistic to virulent factors. Biologically synthesized silver nanoparticles (AgNPs) are reported as anti-QS and anti-biofilm drugs against bacterial infections. The present study reports on the synthesis and characterization of Piper betle (Pb) mediated AgNPs (Pb-AgNPs). The anti-QS activity of Pb-AgNPs against Chromobacterium violaceum and the potential effect of Pb-AgNPs on QS-regulated phenotypes in PAO1 were studied. FTIR analysis exhibited that Pb-AgNPs had been capped by phytochemical constituents of Pb. Eugenol is one of the active phenolic phytochemicals in Pb leaves, therefore molecular docking of eugenol-conjugated AgNPs on QS regulator proteins (LasR, LasI and MvfR) was performed. Eugenol-conjugated AgNPs showed considerable binding interactions with QS-associated proteins. These results provide novel insights into the development of phytochemically conjugated nanoparticles as promising anti-infective candidates.     

Clickable gold nanoparticles for streamlining capture,enrichment and release of alkyne-labelled proteins

Alkyne-labelled proteins are generated as key intermediates in the chemical probe-based approaches to proteomics analysis. Their efficient and selective detection and isolation is an important problem. We designed and synthesized azide-functionalized gold nanoparticles as new clickable capture reagents to streamline click chemistry-mediated capture, enrichment and release of the alkyne-labelled proteins in one-pot to expedite the post-labelling analysis. Because hydrophobic surface functionalities are known to render gold nanoparticles poorly water-dispersible, hydrophilic PEG linkers with two different lengths were explored to confer colloidal stability to the clickable capture reagents. We demonstrated the ability of the capture reagents to conjugate the alkyne containing proteins at a nanomolar concentration via click chemistry, which can be immediately followed by their enrichment and elution. Furthermore, a bifunctional clickable capture reagent bearing sulforhodamine and azide groups was shown to conveniently attach a fluorophore to the alkyne-labelled protein upon click capture, which facilitated their rapid detection in the gel analysis.     

Heterocyclic β-keto sulfide derivatives of carvacrol: Synthesis and copper (II) ion reducing capacity

Sixteen β-keto sulfide derivatives of carvacrol (4–19) incorporating phenyl or N, O and S heterocyclic moieties were synthesized in three steps. The relationships between heterocyclic structure and cupric, Cu(II), ion reducing antioxidant capacity (CUPRAC) were examined. Nine of the compounds (8–9 and 13–19) showed better CUPRAC activity than trolox at neutral pH, with trolox equivalent antioxidant capacity (TEAC) coefficients ranging between 1.20 and 1.75. Two derivatives (11–12) showed comparable reducing capacity to trolox, with TEAC values of 0.95 for 11 and 1.02 for 12. Compounds 8–9 and 11–19 were more effective at reducing the Cu(II) ion than ascorbic acid and the parent compound, carvacrol. The most effective antioxidants were those containing an oxadiazole, thiadiazole or triazole moiety. In particular, the methyl thiadiazole derivative (15) had the highest Cu(II) ion reducing capacity, with a TEAC coefficient of 1.73.     

疏水性SERS基底检测应用研究进展

本文简要介绍了表面增强拉曼散射(SERS)的拉曼信号增强原理,常规SERS增强基底的研究应用进展;同时介绍了疏水性基底的定义及优势,并重点综述了疏水性SERS基底的分类及研究应用的进展;最后展望了疏水性SERS基底的研究方向和发展趋势。疏水性SERS基底的发展将有望为今后开展面向超低浓度的生化物质检测以及基于人体体液的疾病的灵敏、客观检测诊断提供新方法和新思路。     

Non‐viral gene delivery for cancer immunotherapy

Recent decades have witnessed the revolutionary development of cancer immunotherapies, which boost cancer‐specific immune responses for long‐term tumor regression. However, immunotherapy still has limitations, including off‐target side effects, long processing times and limited patient responses. These disadvantages of current immunotherapy are being addressed by improving our understanding of the immune system, as well as by establishing combinational approaches. Advanced biomaterials and gene delivery systems overcome some of these delivery issues, harnessing adverse effects and amplifying immunomodulatory effects, and are superior to standard formulations with respect to eliciting antitumor immunity. Nucleic acid‐based nanostructures have diverse functions, ranging from gene expression and gene regulation to pro‐inflammatory effects, as well as the ability to specifically bind different molecules. A brief overview is provided of the recent advances in the non‐viral gene delivery methods that are being used to activate cancer‐specific immune responses. Furthermore, the tumor microenvironment‐responsive synergistic strategies that modulate the immune response by targeting various signaling pathways are discussed. Nanoparticle‐based non‐viral gene delivery strategies have great potential to be implemented in the clinic for cancer immunotherapy.     

Designing chitosan-dextran sulfate nanoparticles using charge ratios

The purpose of this study was to examine the effect of charge ratio on the formation and properties of the chitosan (CS)-dextran sulfate (DS) nanoparticles developed for the delivery of water-soluble small and large molecules, including proteins. Rhodamine 6G (R6G) and bovine serum albumin (BSA) were chosen as model molecules. CS-DS nanoparticles were formulated by a complex coacervation process under mild conditions. The influence of formulation and process variables, including the charge ratio of the 2 ionic polymers, on particle size, zeta potential, and nanoparticle entrapment of R6G and BSA was studied. The in vitro release of R6G and BSA was also evaluated, and the integrity of BSA in the release fraction was assessed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Depending on the concentration and charge ratio of DS and CS, nanoparticles with varied size (>or=244 nm) and zeta potential (-47.1-60 mV) were obtained. High entrapment efficiency (98%) was achieved for both R6G and BSA when the charge ratio of the 2 ionic polymers was greater than 1.12. The release of both R6G and BSA from nanoparticles was based on the ion-exchange mechanism. BSA showed much slower continuous release for up to 7 days while still maintaining its integrity for an extended period. The CS-DS nanoparticles developed based on the modulation of charge ratio show promise as a system for controlled delivery of both small and large molecules, including proteins.     

Synthesis and DNA-cleavage properties of metal complexes of 1,4,7,10-tetraazacyclododecane (cyclen) functionalized with a pendant benzocrown ether

The synthesis and DNA-cleavage properties of a series of novel mononuclear Zn(II), Cu(II), and Co(II) complexes 2 of a crown-ether-functionalized cyclen ligand is described. The Cu complex 2b displayed the highest catalytic activity towards pUC 19 DNA. The effects of reaction time, complex concentration, and pH were investigated, showing that 2b readily and efficiently converts supercoiled (type I ) plasmid DNA to nicked (type II) DNA under physiological conditions (37 degrees, pH 7.4).