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Due to increasing application of nanofibers in many research fields, comprehensive knowledge of the electrospinning process as the most popular method of fiber production is essential. Modeling techniques are valuable tools for managing contributing factors in the electrospinning process, prior to the more expensive experimental techniques. In the present research, effective parameters on the diameter of electrospun polycaprolactone (PCL) nanofibers are analyzed using artificial neural networks (ANN) and response surface methodology (RSM). The assessed parameters include polymer concentration, voltage, and nozzle-to-collector distance. Response surface methodology based on the Box-Behnken design is utilized to develop a mathematical model as well as to determine the optimum condition for production of nanofiber with minimum diameter. In addition, multilayer perceptron neural networks are designed and trained by the sets of input-output patterns using the Levenberg-Marquardt backpropagation algorithm. The high regression coefficient value (R2 ≥ 0.97) and low root-mean-square error (RMSE ≤3.81) of the two models indicate that both models performed well in predicting PCL fiber diameter, although the RSM model slightly outperformed the ANN model in accuracy. The represented models could assist researchers in fabricating electrospun scaffolds with a defined fiber diameter, thus specializing such scaffolds in particular applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Peptide motif sequences of the first helix of osteocalcin (OC) is synthesized in acidic and amidic forms. • An effective dosage of peptides is advanced alkaline phosphatase activity. • The amidated peptide stimulated RNA expression of collagen type I and osteopontin. • Mineral deposition is also considerably increased in the presence of amidated peptide. • The osteocalcin mimetic peptides can be utilized as a bioactive inducer for hard tissue regeneration. Abstract A natural peptide motif in the first helix of osteocalcin (OCN) is used to promote nucleation and crystallization of hydroxyapatite (HA) in hard tissue. The capability of osteocalcin mimetic peptides to induce osteogenic activity of osteoblast cells leading to in-vitro mineralization is demonstrated. An osteocalcin-derived peptide consisting of thirteen amino acids is synthesized in both acidic (OSC) and amidic (OSN) forms and added into the human osteoblast-like cells (MG63) culture. The viability, proliferation, alkaline phosphatase activity, HA deposition and osteogenic gene expression by osteoblast cells are evaluated. It is revealed that the addition of 100 μg/ml of peptides enhances the proliferation rate and total protein content of osteoblast cells. Alkaline phosphatase activity is significantly higher in the presence of peptides which in turn stimulated RNA expression of collagen type I and osteopontin in a phosphate-dependent manner. Alizarin red staining and calcium content measurement show that mineral deposition is considerably increased. Ultrastructural characterization of MG63 cultures confirms the crystalline nature and chemical composition of HA mineral formation in the presence of peptides. It is confirmed that the osteocalcin-derived peptide, particularly in amidic form (OSN), is able to act as a bioactive inducer of mineralization process and hence accelerating bone tissue regeneration. [ABSTRACT FROM AUTHOR]

Abstract Expansion of human induced pluripotent stem cells (h-iPSCs) on mouse derived feeder layers or murine cells secretions such as Matrigel hamper their clinical applications. Alternative methods have introduced novel substrates as stem cell niches or/and optimized combinations of humanized soluble factors as fully defined mediums. Accordingly vitronectin as a main part of ECM have been commercialized significantly as a stem cell niche-forming substrate. In this work, we used a functional peptide derived from vitronectin (VTN) and co-immobilized it with FGF-2 (as an indisputable ingredient of defined culture mediums) on chitosan film surface. After chemical and physical characterization of the pristine chitosan surface as well as ones modified by VTN or/and FGF-2, h-iPS cells were cultured on them at the xeno/feeder-free conditions. Our results demonstrated that co-immobilization of these two biomolecules has a synergistic effect on adhesion and clonal growth of h-iPS cells with maintained expression of pluripotency markers in a FGF-2 density-dependent manner. This is the first report of co-immobilization of an ECM derived molecule and a growth factor for stem cell culture. Graphical abstract Unlabelled Image Highlights • Co-immobilization of an ECM-derived peptide (i.e. vitronectin-derived peptide) and a growth factor (i.e. FGF-2) on the surface (i.e. chitosan film) was accomplished for the first time and confirmed by XPS, fluorometry and ELISA techniques. • The yield of each reaction revealing the surface density of each immobilized biomolecule was estimated which was neglected in the most of immobilization reports. • Feeder/xeno-free culture of human induced pluripotent stem cells (h-iPSCs) on chitosan based surfaces demonstrated that the co-immobilization of vitronectin and FGF-2 has a synergistic effect on attachment, proliferation and colony formation of h-iPS cells with the maintained expression of pluripotency markers in a FGF-2 density-dependent manner. [ABSTRACT FROM AUTHOR]

Fabrication of electrospun chitosan nanofibers is still a controversial issue in publications. Although regarding the lots of reports, mixtures of chitosan with a hydrophilic synthetic polymer such as polyethylene oxide (PEO) have been electrospun successfully, abundance of partly contradictory protocols in which one variable has been surveyed in each study is unfortunately baffling. In the present study, influence of three considerable parameters including the average molecular weight of chitosan, chitosan solution concentration and the mass ratio of polyethylene oxide to chitosan at the mixtures on electrospinning possibility as well as the quality of as-spun fibers is investigated. Eventually, the necessities for obtaining the best results are introduced followed by further analysis of optimized nanofibers using atomic force microscopy. According to our results, the blend solutions prepared from the low molecular weight (LMW) chitosan and PEO are efficient for reproducible production of bead-free electrospun nanofibers even in low proportion of polyethylene oxide. [ABSTRACT FROM AUTHOR]

Poly-L-lysine-coated superparamagnetic iron oxide nanoparticles (SPIONs-PLL) were prepared and used as a novel-carrier for the transfer of brain-derived neurotrophic factor (BDNF) into neural stem cells (NSCs) under the beneficial influence of an external magnetic field. Pro-BDNF, a gene from human brain cDNA libraries, was obtained by polymerase chain reaction and constructed in a mammalian expression vector (PSecTag2/HygroB). The nanoparticles (NPs) were examined using Fourier transform infrared spectroscopy, zeta potential, and Transmission electron microscopy. From the results, the levels of BDNF among the transfected and untransfected cells were 30.326 ± 5.9 and 5.85 ± 3.11 pg/mL, respectively, as detected by an ELISA method. Moreover, the enhanced green fluorescent protein vector was used to evaluate the gene expression efficiency for SPIONs-PLL as a non-viral carrier in NSCs. This was performed under the influence of a magnetic field and the transfection reagents (such as Lipofectamine 2000), which served as a positive control. The histological analysis revealed that the concentration of intracellular NPs was significantly higher than intercellular NPs. These results suggest that SPIONs-PLL can serve as a novel alternative for the transfection of BDNF-NSCs and could be used in gene therapy. [ABSTRACT FROM AUTHOR]

Prostate cancer is the second leading cause of death due to cancer in men. Owing to shortcomings in the current treatments, other therapies are being considered. Toxic gene delivery is one of the most effective methods for cancer therapy. Cationic polymers are able to form stable nanoparticles via interaction with nucleic acids electrostatically. Branched polyethylenimine that contains amine groups has notable buffering capacity and the ability to escape from endosome through the proton sponge effect. However, the cytotoxicity of this polymer is high, and modification is one of the applicable strategies to overcome this problem. In this study, PEI was targeted with chlorotoxin (CTX) via N -succinimidyl 3-(2-pyridyldithio) propionate (SPDP) cross-linker. CTX can bind specifically to matrix metalloproteinase-2 that is overexpressed in certain cancers. Melittin as the major component of bee venom has been reported to have anti-cancer activity. This was thus selected to deliver to PC3 cell line. Flow cytometry analysis revealed that transfection efficiency of targeted nanoparticles is significantly higher compared to non-targeted nanoparticles. Targeted nanoparticles carrying the melittin gene also decreased cell viability of PC3 cells significantly while no toxic effects were observed on NIH3T3 cell line. Therefore, CTX-targeted nanoparticles carrying the melittin gene could serve as an appropriate gene delivery system for prostate and other MMP-2 positive cancer cells. [ABSTRACT FROM AUTHOR]

A combination of light-microscopy and image processing has been applied to study naturally deformed Escherichia coli under in vivo condition and at the order of sub-pixel high-resolution accuracy. To classify deflagellated non-dividing E. coli cells to the rod-shape and bent-shape, a geometrical approach has been applied. From the analysis of the geometrical data which were obtained of image processing, we estimated the required effective energy for shaping a rod-shape to a bent-shape with the same size. We evaluated the energy of deformation in the naturally deformed bacteria with minimum cell manipulation, under in vivo condition, and with minimum influence of any external force, torque and pressure. Finally, we have also elaborated on the possible scenario to explain how naturally deformed bacteria are formed from initial to final-stage. [ABSTRACT FROM AUTHOR]

Patterns obtained in two-dimensional gel electrophoresis (2- DE) in the previously published articles suggest a varying number of proteins. To seek the cause of this variation, we investigated the effect of reduction power on the overall tear proteome maps. To this end, the buffers of two reducing agents, dithiothreitol ( DTT) at nine different concentrations and di-(2-hydroxyethyl) disulfide ( HED), were examined. The assay showed that HED clearly improved 2- DE resolution, increased the number of detectable protein spots, and offered well-resolved chain regions in comparison with those treated with DTT. Furthermore, this study introduced increasing the reduction power as a remedy to increase the reproducibility of two-dimensional human tear proteome maps. In addition, the results of our assessment showed that improved reduction efficiency was accompanied by increased procedure reproducibility from 42% to 89%. [ABSTRACT FROM AUTHOR]

This review discusses recent advances and the reported strategies over the last ten years on the use of carbon-based quantum dots (QDs), including carbon dots (CDs), graphene quantum dots (GQDs), and polymer dots (PDs) in the design of fluorescence imaging and biosensing system for early diagnosis of cancers. Besides, this study comprehensively reports the latest developments in these years in the fluorescence imaging (FI) area with special attention to carbon-based QDs that take advantage of the excellent properties offered by these zero-dimensional (0D) nanomaterials as fluorescent tags. The most remarkable advantages of these carbon nanomaterials in the development of fluorescence sensing and imaging strategies compared to the conventional dyes arise from sharp emission spectra, long photostability, low-cost synthesis, reliability, reproducibility, high fluorescent intensity, and high surface functional groups such as carboxyl and amide, which impart better solubility in many solvents and aqueous media and facilitate their easy functionalization with biological species. The final section discusses the main challenges to be met to take full advantage of these properties in fluorescence bio-sensing and imaging as well as the possible future trends in this field based on the great advances that have occurred in recent years. [Display omitted] • A review on fluorescence imaging and bio-sensing systems for early diagnosis of cancers. • Recent strategies reported for the use of carbon-based quantum dots. • Design and applications of carbon dots (CDs). • Design and applications of graphene quantum dots (GQDs). • Design an applications of polymer dots (PDs). [ABSTRACT FROM AUTHOR]

Herein, iron-gold core shell magnetic nanoparticles Fe@Au NPs was investigated as contrasting agent in radiation therapy in the breast cancer. Assessment of cytotoxic and radio sensitizing potential was done by MTT method and Flow cytometry. Radiation was done using Co 60 source. The response of cells to treatment with radiation alone and radiation with nanoparticles was assessed. The study demonstrates that Fe@Au nanoparticles do not have considerable cytotoxic effects, but they increase the effectiveness of radiation that means the survival of the group without nanoparticles exposed to 5 Gy radiations is 75%while the group with nanoparticles is 33%. With 2 Gy radiations the survival of the two groups are 87% and 80% respectively. [ABSTRACT FROM AUTHOR]

Abstract: Although stainless steel has a good biocompatibility for most clinical cases, the higher tissue response (bone bonding property) is required in orthopedic field. In this study, to improve bone-bonding ability of stainless steel substrates, a specific sequence of osteocalcin mimetic peptide is used as bioactive coating material to biochemically modify the surface of metallic samples. This sequence consists of thirteen amino acids present in the first helix of osteocalcin is synthesized in amidic form and physically adsorbed on the surface of 316LS (316 low carbon surgical grade) stainless steel substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to characterize the surface of peptide coated and uncoated substrates. The bioactivity and bone bonding ability of coated and uncoated substrates are assessed by level of hydroxyapatite formation, using transmission electron microscopy (TEM), energy-dispersive x-ray (EDS), and scanning electron microscopy (SEM). The pre-osteoblast cell attachment and proliferation are also evaluated by MTT assay. The results show that the surface of coated sample is homogenously covered by the peptide and display a rougher surface relative to uncoated sample. TEM images reveal the formation of plate-like hydroxyapatite crystals in the presence of the peptide and an amorphous calcium phosphate phase without the peptide. Pre-osteoblast cells proliferation is significantly higher on the surface of peptide coated substrate, while cell attachment remains unaffected by the peptide coatings. Pre-osteoblast cells also demonstrate a higher degree of spreading on the surface of coated sample. It is believed that osteocalcin mimetic peptide improve surface bioactivity and promote hydroxyapatite crystal formation may lead to increased mineralization and bone formation on the surface of metallic biomedical devices. [Copyright &y& Elsevier]

Technical strategies like amino acid substitution and residue modification have been widely used to characterize the importance of key amino acids and the role that each residue plays in the structural and functional properties of protein molecules. However, there is no systematic approach to assess the impact of the substituted/modified amino acids on the conformational dynamics of proteins. In this investigation to clarify the effects of residue modifications on the structural dynamics of human prion protein (PrP), a comparative molecular dynamics simulation study on the native and the amino acid-substituted analog at position 208 of PrP has been performed. It is believed that Arginine to Histidine mutation at position 208 is responsible for the structural transition of the native form of human prion protein to the pathogenic isoform causing Creutzfeldt-Jakob disease (CJD). So, three 10 ns molecular dynamics simulations on three model constructs have been performed. Simulation results indicated considerable differences of conformational fluctuations for Alanine substituted construct (PrPALA) and the analog form (PrPSB) comprising the neutralized state of the Arginine residue at position 208 of the human prion protein. According to our data, substitution of the Arginine residue by the uncharged state of this residue induces some reversible structural alterations in the intrinsically flexible loop area including residues 167-171 of PrP. Thus, deprotonation of Arg208 is a weak perturbation to the structural fluctuations of the protein backbone and the resulting construct behaves almost identical as its native form. Otherwise, Alanine substitution at position 208 imposed an irreversible impact on the secondary and tertiary structure of the protein, which leads to conformational instabilities in the remote hot region comprising residues 190-195 of the C-terminal part of helix 2. Based on the results, it could be deduced that the observed conformational transitions upon Arg208 to His point mutation, which is the main reason for CJD, may be mainly related to the structural instabilities due to the induced-conformational changes that caused alterations in local/spatial arrangements of the force distributions in the backbone of the human prion protein. [ABSTRACT FROM AUTHOR]

Genesis of natural biocomposite-based materials, such as bone, cartilage, and teeth, involves interactions between organic and inorganic systems. Natural biopolymers, such as peptide motif sequences, can be used as a template to direct the nucleation and crystallization of hydroxyapatite (HA). In this study, a natural motif sequence consisting of 13 amino acids present in the first helix of osteocalcin was selected based on its calcium binding ability and used as substrate for nucleation of HA crystals. The acidic (acidic osteocalcin-derived peptide (OSC)) and amidic (amidic osteocalcin-derived peptide (OSN)) forms of this sequence were synthesized to investigate the effects of different C termini on the process of biomineralization. Electron microscopy analyses show the formation of plate-like HA crystals with random size and shape in the presence of OSN. In contrast, spherical amorphous calcium phosphate is formed in the presence of OSC. Circular dichroism experiments indicate conformational changes of amidic peptide to an open and regular structure as a consequence of interaction with calcium and phosphate. There is no conformational change detectable in OSC. It is concluded that HA crystal formation, which only occurred in OSN, is attributable to C-terminal amidation of a natural peptide derived from osteocalcin. It is also proposed that natural peptides with the ability to promote biomineralization have the potential to be utilized in hard tissue regeneration. [ABSTRACT FROM AUTHOR]

Aurein1.2 is a cationic peptide with antimicrobial and anticancer activity. In order to find a novel peptide with this activity, aurein1.2 was utilized as a template and the sequences were designed by a RosettaDesign server with our proposed pattern. As a result, tempY was designed and synthesized, and its structural and biological activity was investigated. TempY has a sequence similar to that of the temporins group but with potent antibacterial properties against Gram-positive bacteria and effective anticancer activity (LC is 20-30 μg/ml). This latter activity may be due to the tyrosine at the C terminus of the peptide. Kar peptide is another model derived from the complete design of aurein1.2. Kar is only active against A549 cells. The net charge of Kar is four, and it is inactive against Gram-positive bacteria and MCF-7 cells, which may be due to the high positive-charge density on the surface of peptide. [ABSTRACT FROM AUTHOR]

Abstract: The industrial utilization of savinase is mainly constrained by its stability limitations. In the present study, the irreversible thermoinactivation of savinase has been evaluated at 70°C, and various possible mechanisms for irreversible thermoinactivation of savinase were examined. The main process seemed to be autodigestion of savinase at higher temperatures. To improve the thermal stability of the enzyme, the effect of two co-solvents (sorbitol and trehalose) on the enzyme''s activity and stability was investigated. Both osmolytes prevented the autolysis of savinase at 70°C without inactivating the enzyme; furthermore, the structural and kinetic stabilities of the enzyme increased in the presence of additives. [Copyright &y& Elsevier]

Abstract: Molecular dynamics simulation method is used to assess the contribution of a disease-associated salt bridge in the early stages of the conformational rearrangement of human prion protein upon Arg208→His mutation, which causes Creutzfeldt–Jakob disease. Previous investigations have suggested that the breakage of this putative salt bridge (D144/E146 ↔Arg208) between helix 1 and helix 3 is responsible for such a mutation-driven process. So far, no experimental data has been reported in order to distinguish the contribution of this single salt bridge in the initial steps of amyloid formation. Consequently, we decided to investigate the role of this salt bridge in early conformational rearrangements. To remove the salt bridge without perturbations in the backbone structure, the neutralized states of the involved residues were used. Three 10-ns molecular dynamics simulations on three initial structures have been performed. The results revealed that the early stages of the conformational rearrangements, against common belief, are mainly associated with the mutation-induced global changes in the backbone dynamics but not with the breaking of the salt bridge. [Copyright &y& Elsevier]

Abstract: Process development and optimization studies were performed in order to improve the purification process of (rhIFN-γ). The objective was to generate material with higher purity and quantity. An in-process control screening was developed to obtain the optimal condition for column chromatographic purification by measuring LPS, nucleic acids, rhIFN- γ, monomer and its covalent dimers. A new resin screening method was applied to select optimal resin for each of the chromatographic columns. The resulting process used Butyl and Q-Sepharose, refolding and SP-Sepharose for purification of IFN-γ. Effects of different process conditions such as cell lysis, removal of impurity and oxygen concentration were evaluated. Removal of impurities was evaluated by washing of inclusion bodies with 1% Triton X-100 and 3M urea and different chromatography steps. The results reveal that Triton removed about 43% of the LPS but urea had no effect on removal of nucleic acids and LPS. Further analysis show that removal of impurities by column chromatography decreases aggregation and increases the process yield. Oxygen concentration was identified as parameter that could have a significant impact on covalent dimers formation, as an unacceptable pharmaceutical form of rhIFN-γ. On the basis of small-scale studies, optimum operating conditions were chosen and the purification process was successfully scaled-up to a pilot scale process with step yield and product quality that were better than previous reports. [Copyright &y& Elsevier]

Abstract: We decided to investigate the influence of the presence of disulfide bonds on the pattern of force distribution in the functional site of scorpion toxin BMK M1 in its functional state. Therefore, a series of short time molecular dynamics (MD) simulations were performed on this toxin in the native state and disulfide bond broken states. The comparison of disulfide bond broken states with the native state showed that the electrostatic potential energy of important functional residues in the reverse turn and C-terminal regions were modulated by the cooperative effect of all disulfide bonds in the molecule. Furthermore, our results revealed that disulfide bonds also play a cooperative role in modulating (1) the amplitude of the fluctuations of the functional segments and (2) the correlation of motions between important functional residue pairs in this toxin. Therefore, we can conclude that the disulfide bonds have cooperation to adjust the pattern of force distribution in the functional site of this toxin in its functional state. [Copyright &y& Elsevier]

Abstract: Bacillus sp. KR-8104 was selected from a set of 18 bacteria strains isolated from soil samples and screened for production of amylase. The maximum productivity obtained at pH 5–6 and 60–65h after cultivation in production medium. New extracellular Ca-independent α-amylase was highly purified using ion exchange and hydrophobic interaction chromatography, which showed a single band with an apparent molecular weight of 59kDa by SDS-PAGE. This enzyme is active in a wide pH range with its maximum activity at low pH values (4.0–6.0) and has the 90% of its maximum activity at pH 3.5. The α-amylase is optimally active at 75–80°C. The presence or absence of Ca2+ and EDTA did not affect enzyme activity and thermal stability. [Copyright &y& Elsevier]

Pseudomonas aeruginosa is the most common pathogen that causes chronic lung infections and recurrence of the disease in cystic fibrosis patients by hiding inside cells and biofilm matrix. Herein, we developed gentamicin and curcumin-loaded lipid-polymer hybrid nanoparticle- (termed CG-HNPs) to evaluate in vitro activities against biofilm-embedded P. aeruginosa and compared with lipid nanoparticles containing the same drugs (CG-Lip). The nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), fluorescence spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy, which demonstrated that HNPs with a diameter of approximately 340 nm were uniform. The optimal CG-HNPs formulation illustrated high encapsulation (∼70%) and controlled release characteristics (gradually released in 72 h). The antibacterial activities of generated nanoparticles are maintained against planktonic and biofilm bacteria and it is effective in damage established biofilms. Besides, HNPs were biocompatible and nontoxic to J774 and HFF cell lines and uptake by the macrophages (J774), which facilitated the killing of intracellular bacteria in macrophages. These results introduced CG-HNPs as a promising antibacterial agent for the treatment of chronic infections and intracellular bacteria due to excellent antibacterial activity. [ABSTRACT FROM AUTHOR]

'Active targeting' refers to modifying a nanocarrier's surface with targeting ligands. This study introduced an efficient approach for immobilizing imidazole-based drugs onto the metallated-porphyrin complex within the porphysome nanocarrier. To enhance cellular and bacterial uptake, a Ni-porphyrin with a fatty acid tail was synthesized and placed in the bilayer center of DPPC, facilitating receptor-mediated endocytosis. The Ni-porphyrin in the head group of the Ni-porphyrin-tail was placed superficially in the polar region of the membrane. Spherical unilamellar vesicle formation (DPPC: Ni-porphyrin-tail 4:1 mole ratio), as metallo-porphysome, was achieved through supramolecular self-assembly in an aqueous buffer. These vesicles exhibited a diameter of 279 ± 7 nm and a zeta potential of −15.3 ± 2.5 mV, showcasing their unique cytocompatibility. Nitroimidazole was decorated on the surface of metallo-porphysomes and pistachio green hull extract (PGHE) was loaded into the carrier for synergistic activity against (E. coli) and (S. aureus) bacteria strains. The physicochemical properties of Nitroimidazole-porphysome-PGHE, including size, zeta potential, morphology, loading efficiency, and release profile under various pH and temperature conditions in simulated gastrointestinal fluids were characterized. This combination therapy prevented bacterial cell attachment and biofilm formation in Caco-2 cells, as colon epithelial cells. The remarkable benefit of this system is that it does not affect cell viability even at 0.5 mg/ml. This study demonstrates the potential of a new co-delivery system using biocompatible metallo-porphysomes to decrease bacterial infections. [ABSTRACT FROM AUTHOR]

• Conductive nanofibers were fabricated from polycaprolactone, gelatin and polypyrrole. • Blend nanofibers of polycaprolactone-gelatin (PCL-Gel) fabricated by electrospinning. • Polypyrrole was coated on the surface of PCL-Gel nanfibers by chemical polymerization. • Chemical, morphological and electrical characterization of the scaffolds were developed. Electrically conductive nanofibrous meshes composed of polypyrrole, polycaprolactone and gelatin construct using a two-step approach including electrospinning and in situ polymerization. Nanometer-scale thick polypyrrole (PPy) is grown on the surface of electrospun polycaprolactone-gelatin (PCL-Gel) nanofiber by in situ chemical polymerization. Different PCL-to-gel ratios and fiber orientations are employed to construct template scaffolds for the coating reaction. SEM analysis indicates the fiber diameter of 162–207 nm and the coating thickness of 30–93 nm. Porosity estimation confirms conservation of total porosity in the coated mats. ATR-FTIR of the composite reveals that functional groups of all three polymers partially exist on the surface. Furthermore, XRD analysis verifies the crystalline nature of the hybrid scaffold. High electrical conductivity (4.6–5.8 S/cm) and convenient mechanical properties of the coated membranes are further achieved. The collective information of the current investigation introduces suitable potential candidates for diverse biomedical applications. [ABSTRACT FROM AUTHOR]

Wnt/β-catenin signaling, a highly evolutionary conserved pathway, is abnormally regulated in many human cancers. This pathway is one of the proposed mechanisms of atrial natriuretic peptide (ANP) anti-cancer effect. ANP which at first reported as a cardio hormone, inhibits proliferation of different cancer cell lines and tumor growth in vitro and in vivo respectively. Previous studies have shown a possibility of direct interaction between ANP and Frizzled (FZD), the main extracellular receptor of the pathway, and so a competition between ANP and Wnt for binding to this receptor. Here, using a molecular dynamics approach, we investigated this hypothesis validity and also the probable mechanism involved. We found three overlapping binding regions between ANP and Wnt3a carboxyl-terminal domain (CTD) on FZD7, but there is not any overlap with the large amino-terminal domain (NTD) of this protein. Based on the results derived from our study and the previous report on the intrinsic inhibitory potential of NTD subdomain against Wnt signalling and the conserved structure of Wnt-FZD complex architecture, we concluded that ANP is able to compete with Wnt CTD for binding to FZD that it can lead to incompletion of complex formation procedure between Wnt3a and FZD7. Finally, we introduce this peptide as a potential scaffold to design selective inhibitors against FZD-dependant cancers. [ABSTRACT FROM AUTHOR]

Lung cancer is one of the deadliest cancers worldwide due to the inability of existing methods for early diagnosis. Tumor-derived exosomes are nano-scale vesicles released from tumor cells to the extracellular environment, and their investigation can be very useful in both biomarkers for early cancer screening and treatment assessment. This research detected the exosomes via an ultrasensitive electrochemical biosensor containing gold nano-islands (Au-NIs) structures. This way, a high surface-area-to-volume ratio of nanostructures was embellished on the FTO electrodes to increase the chance of immobilizing the CD-151 antibody. In this way, a layer of gold was first deposited on the electrode by physical vapor deposition (PVD), followed by thermal annealing to construct primary gold seeds on the surface of the electrode. Then, gold seeds were grown by electrochemical deposition through gold salt. The cell-derived exosomes were successfully immobilized on the FTO electrode through the CD-151 antibody, and cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were used in this research. In the CV method, the change in the current passing through the working electrode is measured so that the connection of exosomes causes the current to decrease. In the EIS method, surface resistance changes were investigated so that the binding of exosomes increased the surface resistance. Various concentrations of exosomes in both cell culture and blood serum samples were measured to test the sensitivity of the biosensor, which makes our biosensor capable of detecting 20 exosomes per milliliter. [ABSTRACT FROM AUTHOR]

Lamellar and hexagonal lipid structures are of particular importance in the biological processes such as membrane fusion and budding. Atomistic simulations of formation of these phases and transitions between them are computationally prohibitive, hence development of coarse-grained models is an important part of the methodological development in this area. Here we apply systematic bottom-up coarse-graining to model different phase structures formed by 1,2-dioleoylphosphatidylethanolamine (DOPE) lipid molecules. We started from atomistic simulations of DOPE lipids in water carried out at two different water/lipid molar ratio corresponding to the lamellar Lα and inverted hexagonal HII structures at low and high lipid concentrations respectively. The atomistic trajectories were mapped to coarse-grained trajectories, in which each lipid was represented by 14 coarse-grained sites. Then the inverse Monte Carlo method was used to compute the effective coarse-grained potentials which for the coarse-grain model reproduce the same structural properties as the atomistic simulations. The potentials derived from the low concentration atomistic simulation were only able to form a bilayer structure, while both Lα and HII lipid phases were formed in simulations with potentials obtained at high concentration. The typical atomistic configurations of lipids at high concentration combine fragments of both lamellar and non-lamellar structures, that is reflected in the extracted coarse-grained potentials which become transferable and can form a wide range of structures including the inverted hexagonal, bilayer, tubule, vesicle and micellar structures. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) nanocomposites have attracted much attention in biomedical and catalytic fields due to their outstanding water dispersibility, cell permeability, high mobility of charge carriers, etc. This article reports the successful synthesis of GO–Co3O4 and phytic acid (PA)-modified GO–Co3O4 (GO–Co3O4–PA) nanocomposites by a facile hydrothermal method and studies of their antiproliferative properties. Various analyses were performed to characterize the synthesized nanocomposites. XRD revealed the characteristic crystallinity of GO–Co3O4 and GO–Co3O4–PA. FT-IR spectroscopy identified the different functional groups of nanocomposites. FE-SEM, AFM, EDX, and DLS analyses of GO–Co3O4–PA demonstrated multigonal particles with an average size of 837 nm on the basal planes of GO with signatures of Co and P. The zeta potential was −49.9 mV for GO–Co3O4–PA, which showed the moderate stability of nanocomposites. The Raman spectra of GO–Co3O4 and GO–Co3O4–PA nanocomposites indicated an increase in the surface defect density of GO due to the adsorption of Co3O4 and PA on the surface of GO. The use of nanocomposites for targeted breast cancer therapy was evaluated via an MTT assay. GO–Co3O4–PA showed considerable cytotoxicity with an IC50 value of 12.94 μg mL−1 towards the breast cancer cell line (MCF-7), which was five times lower than that of GO–Co3O4 (64.36 μg mL−1). As an anticancer agent, PA enhances the interaction of MCF-7 cell lines with nanocomposites and leads to higher cytotoxicity. MTT cytotoxicity, Annexin V/PI double staining, and intracellular reactive oxygen species (ROS) assays were performed. The GO–Co3O4–PA nanocomposite is a promising candidate for breast cancer therapy. Quantum mechanical calculations based on the DFT-D correction and PA adsorption on GO and GO–Co3O4 (1 0 0) in the presence of water were done in the adsorption locator module. Free energy calculations showed that adsorption is a spontaneous and more favorable process. Molecular docking studies were conducted to investigate the interaction of compounds on human topoisomerase IIα bound to DNA (4fm9) and Bcl-2 protein. The results indicated that GO–Co3O4–PA could properly dock into more amino acids with high negative energy scores and confirmed the MTT data. Moreover, GO–Co3O4–PA nanocomposites exhibited excellent catalytic ability towards the Biginelli reaction and showed significant advantages including excellent yields, mild reaction conditions, and short reaction times. [ABSTRACT FROM AUTHOR]

Chitosan (CHS) and chitin (CHT) biopolymers have found many applications in the field of controlled-release drug delivery systems. Herein, molecular dynamics (MD) simulation and binding free energy calculations were used to investigate the potentials of CHS and CHT polymers for the controlled release of follicle-stimulating hormone (FSH). The results indicated that FSH conformation did not change in the presence of CHS and CHT. In addition, FSH-polymer interactions caused stability of the 3 10 -helix structure of the alpha subunits of FSH (FSHα). Both the biopolymers interacted with the protein mainly through the hydrophobic forces. CHS has more affinity for FSH when compared with CHT. Furthermore, in both systems, the affinity of polymers for FSHα was more than that for beta subunits of FSH (FSHβ). The results suggested that the polysaccharides might improve the controlled-release FSH delivery. [ABSTRACT FROM AUTHOR]

Exposure to mustard gas can lead to variations in the proteome of corneal epithelium cells and after a latency period produces delayed symptoms in the eyes of chemical victims. Hence, a comparative proteome analysis was conducted between the corneal epithelial cells of chemical victims from Iran-Iraq war (1980–1988) and healthy donors. To this end, corneal epithelium samples from victims and healthy individuals were collected, and the proteome of these samples were prepared for two-dimensional electrophoresis and the analysis of spots by statistical software. Selected spots were further analyzed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. Twenty four proteins were identified of which eighteen proteins showed downregulation while six proteins were upregulated in the victims in comparison to the normal individuals. Also, six protein spots were confirmed by western-blot analysis. In conclusion, all the twenty-four identified proteins are involved in pathways which their up- or down-regulation leads to the accumulation of undesired substrates, cell death and apoptosis. Bioinformatics' tools indicated that these identified proteins were involved in various metabolic processes, DNA damage response, immune response and etc. The present study provides a suitable platform for further clinical studies. [ABSTRACT FROM AUTHOR]

Follicle-stimulating hormone (FSH) is widely applied in the modern ovarian stimulation techniques. However, it must be administered daily because of its short half-life. Recently, the cholesterol (CS) modified chitosan (CTS) nanogels have attracted significant interest as promising controlled release protein delivery because of their ability to minimize the aggregation and irreversible denaturation of proteins. Herein, we report a molecular dynamics (MD) simulation investigation on the molecular mechanisms of FSH encapsulation in the CS-CTS nanogels. The MD simulations have been performed using the GROMACS software for up to 200 ns simulation time. Furthermore, the binding free energy has been calculated by the molecular mechanics [MM] with Poisson-Boltzmann [PB] and surface area solvation (MM/PBSA) method by using the g_mmpbsa tool. Our findings suggest that the main driving force of the formation of the CS-CTS nanogels is the hydrophobic interactions between the CS–CS moieties in water. The results have also indicated that the CS-CTS nanogel formation can occur through the hydrogen bonding in addition to the hydrophobic interactions. The obtained data demonstrate that the FSH encapsulation into the CS-CTS nanogels is a gradual process driven by the hydrophobic interactions between the hydrophobic patch of FSH and the hydrophobic nanodomains of the nanogel. Our results also reveal that except in the hydrophobic patch region, the flexibility of FSH was reduced in the presence of the nanogel. This study provides the elucidation of the nanogel–FSH interactions at the molecular level and presents new perspective for the ideal design and applications of the CS-CTS nanogel in protein delivery. [ABSTRACT FROM AUTHOR]

Photoinactivation is a common phenomenon in bioluminescence ctenophore photoproteins ( e.g mnemiopsin, berovin and BfosPP) with still unknown mechanism. The activity of coelenterate photoproteins ( e.g aequorin), which has high structural similarity with ctenophore photoproteins, is not affected by light. Recently, we have characterized the effects of light on ctenophore photoprotein mnemiopsin, in different conformations, which has demonstrated light induced structural changes, uniquely secondary structures, of both apo and holo mnemiopsin. This paper is further expansion of our previous work, by applying molecular dynamics simulations to investigate photoinactivation related dynamics of berovin at atomistic level, in comparison with aequorin, under the influence of electric component of electromagnetic field. The results have indicated that the intense electric filed could influence structure of both berovin and aequorin but in different manner, whereas moderate electric field only effects on berovin's structure remarkably. In this case, increased helicity of residues E180-M193 and decreased helical contents of L38-D46 and L125-D138 segments are considerable in berovin as well as flexibility elevation of calcium binding loops. These changes cause structural expansion of berovin, especially at N-terminal domain, in direction of electric field. In conclusion, the induced structural changes of mentioned helical parts together with elevated fluctuation of their adjacent segments, N26-D46 and M193-Y206, indicate the influence of light on substrate stabilizing residues, Arg41 and Y204. This condition could presumably leads to inactivation of bioluminescence reaction due to separation of substrate from the cavity of the protein. [ABSTRACT FROM AUTHOR]

Total-internal reflection fluorescence (TIRF) microscope is a unique technique for selective excitation of only those fluorophore molecules in a cellular environment, which are located at the sub-diffraction axial distance of a cell's contact-area. Despite this prominent feature of the TIRF microscope, making quantitative use of this technique has been a challenge, since the excitation intensity strongly depends on the axial position of a fluorophore molecule. Here, we present an easy-implemented data analysis method to quantitatively characterize the fluorescent signal, without considering the intensity-value. We use F-actin patches in single-melanoma cells as an example and define two quantities of elongation and surface density for F-actin patches at the contact-area of a melanoma cell. The elongation parameter can evaluate the dispersion of F-actin patches at the contact-area of a cell and is useful to classify the attaching, spreading, and expanding stages of a cell. Following that, we present the profile of the surface density of F-actin patches as a quantity to probe the spatio-temporal distribution of the F-actin patches at the contact-area of a cell. The data analysis methods that are proposed here will also be applicable in the image analysis of the other advanced optical microscopic methods. [ABSTRACT FROM AUTHOR]

Valproic acid (VPA) usage in high dose is teratogen with low bioavailability. Hence to improve its efficacy and reduce its side effect it was encapsulated by the Nano liposomes and stabilized by the chitosan at different concentrations. The cellular uptake, biocompatibility, loading and encapsulation efficiency of the six-different formulations (1:1, 2:1, and 4:1 of chitosan-phospholipids: VPA), PC12 differentiation to neuron cells assays (gene-expression level by qRT-PCR) were conducted for the efficacy assessment of the Nano carriers. The encapsulation efficiency (EE) results revealed that the encapsulation of the VPA corresponds to the phospholipids dose, where 2:1 formulations showed higher encapsulating rate (64.5% for non-coated and 80% for coated by chitosan). The time monitored released of VPA also showed that the chitosan could enhance its controlled release too. The cellular uptake exhibited similar uptake behavior for both the coated and the non-coated Nano carriers and cytoplasmic distribution. We witnessed no toxicity effects, at different concentrations, for both formulations. Moreover, the results indicated that the gene expression level of SOX2, NeuroD1, and Neurofilament 200 increased from 1 to 5 folds for different genes. The qRT-PCR data were confirmed by the immunofluorescence antibodies staining, where Neurofilament 68 and SOX2 cell markers were modulated during differentiation of PC12 cells. Finally, our findings suggest promising potential for the Lip-VPA-Chit Nano carrier in inducing the differentiation of PC12 into neuron for treating neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

Objective. Sulfur mustard (SM) is a highly reactive alkylating agent which produces ocular, respiratory, and skin damages. Eyes are the most sensitive organ to SM due to high intrinsic metabolic and rapid turnover rate of corneal epithelium and aqueous-mucous interfaces of the cornea and conjunctiva. Here we investigate underlying molecular mechanism of SM exposure delayed effects which is still a controversial issue after about 30 years. Materials and Methods. Following ethical approval, we have analyzed serum proteome of ten severe SM exposed male patients with delayed eye symptoms with two-dimensional electrophoresis followed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. The western blotting was used to confirm the proteins that have been identified. Results. We have identified thirteen proteins including albumin, haptoglobin, and keratin isoforms as well as immunoglobulin kappa chain which showed upregulation while transferrin and alpha 1 antitrypsin revealed downregulation in these patients in comparison with healthy control group. Conclusions. Our results elevated participation of free iron circulatory imbalance and local matrix-metalloproteinase activity in development of delayed ocular symptoms induced by SM. It demonstrates that SM induced systemic toxicity leads to some serum protein changes that continually and gradually exacerbate the ocular surface injuries. [ABSTRACT FROM AUTHOR]

The simulated liposome models provide events in molecular biological science and cellular biology. These models may help to understand the cell membrane mechanisms, biological cell interactions, and drug delivery systems. In addition, the liposomes model may resolve specific issues such as membrane transports, ion channels, drug penetration in the membrane, vesicle formation, membrane fusion, and membrane protein function mechanism. One of the approaches to investigate the lipid membranes and the mechanism of their formation is by molecular dynamics (MD) simulations. In this study, we used the coarse-grained MD simulation approach and designed a liposome model system. To simulate the liposome model, we used phospholipids that are present in the structure of natural cell membranes (1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)). Simulation conditions such as temperature, ions, water, lipid concentration were performed based on experimental conditions. Our results showed a liposome model (ellipse vesicle structure) during the 2100 ns was formed. Moreover, the analysis confirmed that the stretched and ellipse structure is the best structure that could be formed. The eukaryotic and even the bacterial cells have elliptical and flexible structures. Usually, an elliptical structure is more stable than other assembled structures. The results indicated the assembly of the lipids is directed through short-range interactions (electrostatic interactions and, van der Waals interactions). Total energy (Van der Waals and electrostatic interaction energy) confirmed the designed elliptical liposome structure has suitable stability at the end of the simulation process. Our findings confirmed that phospholipids DOPC and DOPE have a good tendency to form bilayer membranes (liposomal structure) based on their geometric shapes and chemical-physical properties. Finally, we expected the simulated liposomal structure as a simple model to be useful in understanding the function and structure of biological cell membranes. Furthermore, it is useful to design optimal, suitable, and biocompatible liposomes as potential drug carriers. [ABSTRACT FROM AUTHOR]

Design and development of novel nanobiomaterials with multifunctional properties hold the promise of new therapeutic strategies to improve the current clinical research in the field of tissue engineering and regenerative medicine. Here, we have successfully synthesized novel autofluorescent hydroxyapatite (HAP) using a template-assisted assembly process followed by a hydrothermal method. Iron quantum cluster (FeQC) were applied as an ideal template for obtaining fluorescent HAP nanorod-assembled microspheres under different hydrothermal temperatures. We evaluated the changes in physicochemical properties, cell viability, and antibacterial activity of HAP microstructures at 120 °C, 150 °C, and 180 °C reaction temperatures. The obtained HAP samples showed an increase in size, a decrease in surface area, and also, a change in the emission wavelength range when the synthesis temperature increases. The cytotoxicity assay results of human amniotic membrane epithelial cells and C2C12 cell line revealed that the HAP with the higher specific surface area show more interaction with cells which lead to higher cytotoxicity effect. The produced HAPs displayed an inhibition zone for Escherichia coli and Staphylococcus aureus bacteria. Therefore, they showed synergistic antibacterial activity against both Gram-negative and Gram-positive bacteria. Our data clearly revealed that the presented biocompatible, multicolor, and highly stable fluorescent HAPs with considerable antibacterial and antioxidant activity have great potential for imaging applications as well as the prevention of implant-associated infections. [Display omitted] • A novel fluorescent Hydroxyapatites (HAP) were fabricated at different hydrothermal temperatures. • The fluorescent HAP samples were synthesized using iron quantum cluster as a template. • The produced HAPs exhibited multicolor fluorescence emission. • The Fluorescent HAP samples exhibited cell-type dependence cytotoxic activity. • The synthesized HAPs showed potent antibacterial effect against E.coli and S.aureus bacteria. [ABSTRACT FROM AUTHOR]

Horseradish peroxidase is an all alpha-helical enzyme, which widely used in biochemistry applications mainly because of its ability to enhance the weak signals of target molecules. This monomeric heme-containing plant peroxidase is also used as a reagent for the organic synthesis, biotransformation, chemiluminescent assays, immunoassays, bioremediation, and treatment of wastewaters as well. Accordingly, enhancing stability and catalytic activity of this protein for biotechnological uses has been one of the important issues in the field of biological investigations in recent years. In this study, pH-induced structural alterations of native (HRP), and modified (MHRP) forms of Horseradish peroxidase have been investigated. Based on the results, dramatic loss of the tertiary structure and also the enzymatic activity for both forms of enzymes recorded at pH values lower than 6 and higher than 8. Ellipticiy measurements, however, indicated very slight variations in the secondary structure for MHRP at pH 5. Spectroscopic analysis also indicated that melting of the tertiary structure of MHRP at pH 5 starts at around 45° C, which is associated to the pKa of His 42 that has a serious role in keeping of the heme prostethic group in its native position through natural hydrogen bond network in the enzyme structure. According to our data, a molten globule like structure of a chemically modified form of Horseradish peroxidase at pH 5 with initial steps of conformational transition in tertiary structure with almost no changes in the secondary structure has been detected. Despite of some conformational changes in the tertiary structure of MHRP at pH 5, this modified form still keeps its catalytic activity to some extent besides enhanced thermal stability. These findings also indicated that a molten globular state does not necessarily preclude efficient catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: Firefly bioluminescence reaction in the presence of Mg2+, ATP and molecular oxygen is carried out by luciferase. The luciferase structure alterations or modifications of assay conditions determine the bioluminescence color of firefly luciferase. Among different beetle luciferases, Phrixothrix hirtus railroad worm emits either yellow or red bioluminescence color. Sequence alignment analysis shows that the red-emitter luciferase from Phrixothrix hirtus has an additional arginine residue at 353 that is absent in other firefly luciferases. It was reported that insertion of Arg in an important flexible loop350–359 showed changes in bioluminescence color from green to red and the optimum temperature activity was also increased. To explain the color tuning mechanism of firefly luciferase, the structure of native and a mutant (E354R/356R/H431Y) of Lampyris turkestanicus luciferase is determined at 2.7Å and 2.2Å resolutions, respectively. The comparison of structure of both types of Lampyris turkestanicus luciferases reveals that the conformation of this flexible loop is significantly changed by addition of two Arg in this region. Moreover, its surface accessibility is affected considerably and some ionic bonds are made by addition of two positive charge residues. Furthermore, we noticed that the hydrogen bonding pattern of His431 with the flexible loop is changed by replacing this residue with Tyr at this position. Juxtaposition of a flexible loop (residues 351–359) in firefly luciferase and corresponding ionic and hydrogen bonds are essential for color emission. [Copyright &y& Elsevier]

Abstract: It has been lately proposed that the interaction between like-charged residues stabilizes the native state of proteins. To explore this, we created a histidine–histidine pair in the Ca-III binding site of the Bacillus amyloliquefaciens α-amylase (BAA) and then examined the impact of this pairing on the BAA. For this purpose, we used site-directed mutagenesis (SDM) to substitute Pro407 with His, Ala, Gln, Arg, and Glu in the BAA. Subsequently, thermostability, kinetic parameters and structural properties of these variants were measured. Moreover, His–His pairing effect on the BAA thermostability was examined by simultaneous mutation of two residues (P407H/H406A and P407H/H406N). The data exhibited a significant improve in thermostability and structural features of enzyme by His replacement instead of Pro407. Other substitutions in this site did not have a significant effect on the enzyme properties, except for P407R, which yielded a partial improvement. The results also showed that the thermostabilities of double mutants significantly decreased compared with that of the P407H mutant. Moreover, the thermostability of P407H remarkably increased compared with that of other variants even in the absence of Ca2+. Our data clearly demonstrated that His406–His407 pairing was the major cause for improved thermal stability. [Copyright &y& Elsevier]

Firefly luciferase is a monooxygenase that catalyzes the ATP-dependent conversion of firefly luciferin into a luciferyl-adenylate, which is oxidized to an electronically excited oxyluciferin in a multistep reaction and produces visible light with a remarkable quantum yield. [he bioluminescence color of firefly luciferases is determined by the luciferase structure and assay conditions. Among different beetles, only luciferase from Phrixotrix railroad worm (PhRE) emits red bioluminescence, naturally. The presence of Arg353 in P/IRE luciferase, which corresponds to the deleted residue in the other luciferases, is an important distinctive structural feature of it. Insertion of Arg356 into a green-emitter luciferase (Lampyris turkestanicus), corresponding to Arg353 in Phrixotrix hirtus, changed the emitted light from green to red. To further clarify the effect of this position on the light shift mechanism, four residues with similar sizes but different charges (Arg, Lys, Glu, and Gin) were inserted into Photinus pyralis luciferase, using site-specific insertion mutagenesis. Insertion of a residue with a positive side chain (Arg356 and Lys356) changed the light color to red, while insertion of a residue with a negative side chain (Glu356) had little effect on color. Insertion of a neutral residue (Glu356) at this position was performed without any change in bioluminescence spectra. Insertion of positively charged residues in this loop took place with a series of structural changes which were confirmed by fluorescence spectroscopy and homology modeling. Homology modeling reveals the appearance of a bulge in a flexible loop (T352-P359) upon mutation which shifts to the left side with a color change from green to red. [ABSTRACT FROM AUTHOR]

Abstract: Chemical cross-linking of a mesophilic α-amylase from Bacillus amyloliquefaciens (BAA) was carried out. Intra-molecular cross-links between lysine residues upon treatment of the enzyme with ethylene glycol bis(succinic acid N-hydroxy succinimide ester) resulted in enhancement of thermostability as indicated by irreversible thermoinactivation experiments. Enhancement of thermostability coincided with a dramatic protection against aggregation, combined with a decrease in surface hydrophobicity. Deamidation, another important mechanism of irreversible thermoinactivation, was also diminished upon modification. While no significant changes in the kinetic parameters are evident, rigidification of the protein structure is suggested by circular dichroism (CD) and fluorescence studies. [Copyright &y& Elsevier]

Chemical modification of lysine residues in glucose oxidase was carried out using citraconic anhydride. Modification brought about changes in the kinetic properties of the enzyme as evident by substantial lowering of Vmax and Km. Enhancement of tryptophan fluorescence was observed with a dramatic change in its pH dependence due to modification. Near- and far-UV circular dichroism spectra of the native and modified forms suggested formation of molten globule-like structures, further supported by 8-anilino-1-naphthalenesulfonic acid fluorescence which indicated higher exposure of hydrophobic residues as a result of chemical modification. [Copyright &y& Elsevier]

In this paper, ab initio calculated NQR parameters for some quinoline-containing derivatives are presented. The calculations are carried out in a search for the relationships between the charge distribution of these compounds and their ability to interact with haematin. On the basis of NQR parameters, π-electron density on the nitrogen atom of the quinoline ring plays a dominant role in determining the ability of quinolines to interact with haematin. This point was confirmed with investigation of Fe+3 cation-π quinoline ring interactions in 2- and 4-aminoquinoline. However, our results do not show any preference for those carbon atoms of the quinoline ring which previous reports have noted. In order to calculate the NQR parameters, the electric field gradient (EFG) should be evaluated at the site of a quadrupolar nucleus in each compound. EFGs are calculated by the Gaussian 98 program using the B3LYP/6-31G* level of theory. [ABSTRACT FROM AUTHOR]

Biomechanical and morphological analysis of the cells is a novel approach for monitoring the environmental features, drugs, and toxic compounds' effects on cells. Graphene oxide (GO) has a broad range of medical applications such as tissue engineering and drug delivery. However, the effects of GO nanosheets on biological systems have not been completely understood. In this study, we focused on the biophysical characteristics of cells and their changes resulting from the effect of GO nanosheets. The biophysical properties of the cell population were characterized as follows: cell stiffness was calculated by atomic force microscopy, cell motility and invasive properties were characterized in the microfluidic chip in which the cells are able to visualize cell migration at a single-cell level. Intracellular actin was stained to establish a quantitative picture of the intracellular cytoskeleton. In addition, to understand the molecular interaction of GO nanosheets and actin filaments, coarse-grained (CG) molecular dynamics (MD) simulations were carried out. Our results showed that GO nanosheets can reduce cell stiffness in MCF7 cells and MDA-MB-231 cell lines and highly inhibited cell migration (39.2%) in MCF-7 and (38.6%) in MDA-MB-231 cell lines through the GO nanosheets-mediated disruption of the intracellular cytoskeleton. In the presence of GO nanosheets, the cell migration of both cell lines, as well as the cell stiffness, significantly decreased. Moreover, after GO nanosheets treatment, the cell actin network dramatically changed. The experimental and theoretical approaches established a quantitative picture of changes in these networks. Our results showed the reduction of the order parameter in actin filaments was 23% in the MCF7 cell line and 20.4% in the MDA-MB-231 cell line. The theoretical studies also showed that the GO nanosheet–actin filaments have stable interaction during MD simulation. Moreover, the 2D free energy plot indicated the GO nanosheet can induce conformational changes in actin filaments. Our findings showed that the GO nanosheets can increase the distance of actin-actin subunits from 3.22 to 3.5 nm and in addition disrupt native contacts between two subunits which lead to separate actin subunits from each other in actin filaments. In this study, the biomechanical characteristics were used to explain the effect of GO nanosheets on cells which presents a novel view of how GO nanosheets can affect the biological properties of cells without cell death. These findings have the potential to be applied in different biomedical applications. [ABSTRACT FROM AUTHOR]

Lung cancer is a leading cause of cancer death in both men and women worldwide. The high mortality rate in lung cancer is in part due to late-stage diagnostics as well as spread of cancer-cells to organs and tissues by metastasis. Automated lung cancer detection and its sub-types classification from cell's images play a crucial role toward an early-stage cancer prognosis and more individualized therapy. The rapid development of machine learning techniques, especially deep learning algorithms, has attracted much interest in its application to medical image problems. In this study, to develop a reliable Computer-Aided Diagnosis (CAD) system for accurately distinguishing between cancer and healthy cells, we grew popular Non-Small Lung Cancer lines in a microfluidic chip followed by staining with Phalloidin and images were obtained by using an IX-81 inverted Olympus fluorescence microscope. We designed and tested a deep learning image analysis workflow for classification of lung cancer cell-line images into six classes, including five different cancer cell-lines (P-C9, SK-LU-1, H-1975, A-427, and A-549) and normal cell-line (16-HBE). Our results demonstrate that ResNet18, a residual learning convolutional neural network, is an efficient and promising method for lung cancer cell-lines categorization with a classification accuracy of 98.37% and F1-score of 97.29%. Our proposed workflow is also able to successfully distinguish normal versus cancerous cell-lines with a remarkable average accuracy of 99.77% and F1-score of 99.87%. The proposed CAD system completely eliminates the need for extensive user intervention, enabling the processing of large amounts of image data with robust and highly accurate results. [ABSTRACT FROM AUTHOR]

Micro-nano scale surface modification of Ti-6Al-4V was investigated through the fascinated modern fiber engraving laser method. The process was performed at a high laser speed of 2000 mm/s, under different laser frequencies (20–160 kHz) and groove distances (0.5–50 μm). Topographic evaluations such as Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FE-SEM) were used to identify the quality and regularity of patterns. The proliferation of human osteoblast-like osteosarcoma cells (MG63) was analyzed by MTT assay for up to 72 h. Also, the plate counting method was used to quantify the viability potential of the modified surface against Escherichia coli bacteria. The cellular viability of the sample modified at the laser frequency of 20 kHz and grooving distance of 50 μm increased up to 35 and 10% compared to the non-treated and control samples, respectively. In the case of the surface modification at lower grooving distances range between 0.5–50 μm, the maximum laser frequency (160 kHz) applied leads to lower pulse's energies and less bacterial adhesion. Otherwise, at groove distances more than 50 μm, the minimum laser frequency (20 kHz) applied reduces the laser pulse overlaps, increases the cell adhesion and antibacterial properties. Surface modification by the fiber engraving laser process significantly enhances the cell adhesion on the surface. As a result of such roughness and cell adhesion enhancement, the surface toxicity feature diminished, and its antibacterial properties improved. [ABSTRACT FROM AUTHOR]

Glucosamine (Glu) is a cartilage and joint fluid matrix precursor that modulates osteoarthritic joint changes. To improve the enzymatic stability, glucosamine was developed into nanoglucosamine by the ionic gelation method through sodium tripolyphosphate (TPP) as cross-linking agent. The optimized mass ratio of Glu:TPP was (3:1) with the particle size 163 ± 25 nm and surface charge −5 mV. Then Sinapic acid (SA) as a natural phenolic acid with strong antioxidant and antimicrobial activities has been grafted onto glucosamine nanoparticles (GluNPs) with grafting efficiency (73 ± 6 %). The covalent insertion of SA was confirmed by UV–Vis, FTIR, 1HNMR, XRD, and FESEM analyses and the other physicochemical properties were also characterized. SA-g-GluNPs showed spherical shape with a mean diameter of 255 ± 20 nm and zeta potential +16 mV. The in vitro release profile of SA-g-GluNPs exhibited the sustained and pH-dependent drug release property. SA-g-GluNPs had a more pronounced effect on reducing the elevated levels of LPS-induced oxidative stress and pro-inflammatory cytokines than free SA in the human chondrocyte C28/I2 cell line. Furthermore, the antibacterial properties against E. coli and S. aureus were also improved by SA-g-GluNPs. This study demonstrated the potential of phenolic acid grafted GluNPs in therapeutic drug applications for chondroprotection and food industries. [Display omitted] • Glucosamine nanoparticles (a chitosan monomer) were synthesized by the ionic gelation method. • Sinapic acid has been grafted to glucosamine nanoparticles by carbodiimide based coupling method. • The anti-inflammatory effect of SA-g-GluNPs on human chondrocyte cell was significantly improved. • The antibacterial properties ameliorated on gram negative and positive bacteria as compared with free SA • The application of Sinapic acid grafted GluNPs in osteoarthritis treatment and cartilage regeneration [ABSTRACT FROM AUTHOR]

Stem cells have a variety of applications in biological, reconstructive medicine, and tissue engineering studies owing to their capacity to differentiate into specific cell lineages and their self-renewal ability. Among the factors affecting stem cells, biochemical agents such as growth and differentiation factors, along with environmental cues including physical and mechanical characteristics of the cell microenvironment, are of interest in this field. Several studies have evaluated the impact of physical factors such as mechanical forces, electric or magnetic fields, and light pulses on stem cell behavior. Also, cell culture substrates that can simulate extracellular matrix in natural conditions are considered the most critical environmental factors. Hence, in this study, we investigated the effects of a specially designed polydimethylsiloxane substrate with a surface pattern for cell contact guidance on various biological and biophysical characteristics of mesenchymal stem cells. Plasma treatment of the substrate under lateral tension from 50 to 200 s caused the increased wavelength of the formed wrinkle structures from 500 ± 56 to 1052 ± 182 nm, respectively, leading to variations of stiffness affecting the cell behaviors. Moreover, by increasing the available surface and hydrophilicity of the substrate, the cell attachment quality improved by more than 46% compared to the control. Finally, results of the mechanics of mesenchymal stem cells on these substrates obtained by bio-AFM showed an increase in the stiffness of cells despite a slight decrease in Young's modulus parameter of different substrates. These changes in the intracellular mechanics can eventually stimulate the more pivotal mechanobiological effects on stem cell fate. [Display omitted] • The physical characteristics of the cellular microenvironment affect mesenchymal stem cell characteristics. • Plasma treatment of nanogrooved substrate increases the stiffness of cells. • Stem cell fate influenced by variations in intracellular mechanics due to biophysical factors. [ABSTRACT FROM AUTHOR]

An unprecedented strategy for the synthesis of highly fluorescent chromeno[4,3‐b]pyrazolo[3,4‐d]pyridin‐4(3H)‐ones via a 1,3‐dipolar cycloaddition reaction/ring closure in the presence of NH4OAc/air oxidation in a one‐pot procedure is described. The molecular structures were characterized by IR spectrophotometry, mass spectrometry, NMR spectroscopy, and single‐crystal X‐ray analysis. Furthermore, the photophysical properties of synthesized compounds were studied by absorption and fluorescence spectroscopy. All of the compounds exhibited almost similar spectra due to their resembling molecular structures. Therefore, one of the synthesized coumarin‐based pyrazolopyridines was selected to evaluate its application as a live‐cell imaging agent by an inverted phase‐contrast microscope. The result reveals that synthesized chromeno[4,3‐b]pyrazolo[3,4‐d]pyridin‐4(3H)‐one has acceptable photostability, low cytotoxicity, satisfactory fluorescence efficiency (Φf: 0.53), and excellent capability to penetrate into the intracellular space. Accordingly, it can be rendered as a promising dye in fluorescence bioimaging. Chemoselectivity, simple and available starting materials, operational simplicity, and good yields are other outstanding advantages of this reaction. [ABSTRACT FROM AUTHOR]