Biodegradable and conductive hyperbranched terpolymers based on aliphatic polyester,poly(D,L-lactide), and polyaniline used as scaffold in tissue engineering

Designing the novel conductive and biodegradable scaffolds based on star-like hyperbranched terpolymers of aliphatic polyester–poly(D,L-lactide)–polyaniline (S-HAP–PLA–PANI) was the purpose of this research. The electroactivity of tissue engineering scaffold, which in the current work was for the presence of PANI, is an essential factor in its performance because the electrical signals are the pivotal physiological stimuli that control the adhesion and differentiation of various cell types. Star-shaped polymers have attracted conspicuous attention, thanks to their low-cost, well-defined highly functionalized structures and low crystallinity, and they also could be an interesting alternative to the linear analogs for their interaction with surrounding tissue and faster degradation rate. In the present work, after 12 weeks, the mass loses for S-HAP–PLA–PANI sample were calculated to be 45%. Scaffolds based on S-HAP–PLA–PANI/PLA nanofibers having the average diameter of 70–200?nm and electrical conductivity of 0.05 S cm^?1 imitated the natural microenvironment of extra cellular matrix to regulate the cell attachment, proliferation, and differentiation.     

Dielectric and mechanical optimization properties of porous poly(ethylene‐co‐vinyl acetate) copolymer films for pseudo‐piezoelectric effect

In this article, the authors present a porous copolymer film with pseudo‐piezoelectric effects as a new candidate material for sensing applications. Porous films of poly(ethylene‐co‐vinyl acetate) (EVA) with a thicknesses ranging from 160 to 310 μm are fabricated by a coextrusion chemical foaming process and charged using a high‐voltage contact charging process. Output performances (piezoelectric constant and relative permittivity) with related thermal/mechanical stability are specifically studied as a function of the film porosity and of the electrical charging process. The piezoelectric constant d₃₃ increases with the cell porosity and an interesting piezoelectric constant close to 5.1 pC/N is achieved with a porous EVA film containing 65% of porosity. Actual results are then discussed using a theoretical solid–gas multilayer model to describe and predict the pseudo‐piezoelectric effect of porous polymer materials. The originality of this work lies in the fact that all the steps leading to optimize pseudo piezoelectric films are included, and also in the use of EVA which is not a standard piezoelectric material. Therefore, this work is a contribution in the development of low‐cost piezoelectric materials with potential applications as sensor in different fields such as medical, security, environment, sport, and transport. POLYM. ENG. SCI., 59:1455–1461 2019. © 2019 Society of Plastics Engineers     

Evaluation of antifungal effect of iron‐oxide nanoparticles against different Candida species

Iron‐oxide nanoparticles (IONPs) have been widely favoured due to their biodegradable, low cytotoxic effects and having reactive surface which can be altered with biocompatible coatings. Considering various medical applications of IONPs, the authors were encouraged to study whether IONPs could be effective against fungal infections caused by Candida species. In this study, IONPs were characterised by scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The goal of this study was to evaluate the antifungal activity of IONPs against different Candida spp. compared with fluconazole (FLC). IONPs were spherical with the size of 30–40 nm. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of IONPs ranged from 62.5 to 500 µg/ml and 500 to 1000 μg/ml, respectively. The MIC and MFC of FLC were in range of 16–128 μg/ml and 64–512 μg/ml, respectively. The growth inhibition value indicated that Candida tropicalis, Candida albicans and Candida glabrata spp. were most susceptible to IONPs. The finding showed that the IONPs possessed antifungal potential against pathogenic Candida spp. and could inhibit the growth of all the tested Candida spp. Further studies, both in vitro and in vivo (including susceptibility, toxicity, Probability of kill (PK) and efficacy studies) are needed to determine whether IONPs are suitable for medicinal purposes.Inspec keywords: iron compounds, nanoparticles, nanomedicine, biomedical materials, microorganisms, cellular biophysics, toxicology, drugs, scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectraOther keywords: antifungal effect, iron‐oxide nanoparticles, Candida species, biodegradable effects, cytotoxic effects, reactive surface, biocompatible coatings, medical applications, IONP, fungal infections, Candidiasis, immunocompromised hosts, antifungal drugs, resistant organisms, antifungal properties, side effects, chemical drugs, scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometer, antifungal activity, disc diffusion, broth microdilution, minimal inhibitory concentration, minimum fungicidal concentration, Candida tropicalis, Candida Albicans, Candida glabrata, antifungal potential, Fe₃ O₄      

A sight on the current nanoparticle-based gene delivery vectors

Nowadays, gene delivery for therapeutic objects is considered one of the most promising strategies to cure both the genetic and acquired diseases of human. The design of efficient gene delivery vectors possessing the high transfection efficiencies and low cytotoxicity is considered the major challenge for delivering a target gene to specific tissues or cells. On this base, the investigations on non-viral gene vectors with the ability to overcome physiological barriers are increasing. Among the non-viral vectors, nanoparticles showed remarkable properties regarding gene delivery such as the ability to target the specific tissue or cells, protect target gene against nuclease degradation, improve DNA stability, and increase the transformation efficiency or safety. This review attempts to represent a current nanoparticle based on its lipid, polymer, hybrid, and inorganic properties. Among them, hybrids, as efficient vectors, are utilized in gene delivery in terms of materials (synthetic or natural), design, and in vitro/in vivo transformation efficiency.     

Poly(vinyl alcohol) membranes in wound-dressing application: microstructure,physical properties,and drug release behavior

Poly(vinyl alcohol) (PVA) hydrogel membranes were prepared through three different preparation methods including freeze-thawing (FT), solution casting (SC) followed by thermal annealing, and phase separation (PS). The prepared hydrogels were characterized by Fourier transform-infrared spectroscopy, X-ray diffractometry, and scanning electron microscopy. Nitrofurazone (NFZ) was then loaded in the hydrogels. FT and SC methods led to obtaining dense membranes, while PS method resulted in an asymmetric one. The effects of hydrogel preparation method on water absorption, gel fraction, water vapor and oxygen permeabilities, bacterial barrier, tensile properties, and drug release profiles were investigated. The water vapor permeability of the hydrogel prepared through PS method was about 1.5 times higher than those obtained through FT and SC methods. Gel formation in PS method is probably responsible for the highest degree of crystallinity, and consequently the maximum gel fraction for the corresponded membrane. The elongation-at-break for this membrane in wet state was 41% higher than that made by FT method and 18% greater than that of SC method. Membranes prepared by all three methods showed excellent barrier property against bacterial penetration during 1 week. The results showed that PS membrane could control the release of NFZ more effectively as compared with the other two samples.     

Purification and partial characterization of antithrombin III from bovine skeletal muscle and possible role of thrombin in postmortem apoptosis development and in efficiency of low voltage electrical stimulation

Thrombin/antithrombin III (AT-III) proteolytic system is well known for its function in blood coagulation. Thrombin is expressed in skeletal muscle but nothing is known about the presence of AT-III in the tissue. In postmortem muscle this system has been and is still totally ignored. We therefore successfully attempted to purify AT-III from bovine skeletal muscle and characterized the purified protein (identified as AT-III by N-ter sequencing and mass spectrometry finger print) for its physicochemical and inhibitory properties. As the human blood serpin, muscle AT-III is thermolabile and stable only at alkaline pH (pH 9–10). The muscle serpin inhibits strongly thrombin in a heparin dependent manner and trypsin. Phosphatidylserine (PS) externalization demonstrated in the present work suggested that prothrombin can be activated to thrombin through binding of the activator complex on the external PS groups. PS externalization is concomitant with shrinkage of muscle fibers indicating that muscle cells are engaged in the cell death program known as apoptosis few minutes after death. We then discussed the potential role of this proteolytic system in postmortem apoptosis development as well as in the control of low voltage electrical stimulation efficiency.     

Data driven analysis of functional brain networks in fMRI for schizophrenia investigation

The purpose of this article is to present a methodology to identify the sources of activity in brain networks from functional magnetic resonance imaging (fMRI) data using the multiset canonical correlation analysis algorithm. The aim is to lay the foundations for a screening marker to be used as indicator of mental diseases. Group analysis blind source separation methods have proved reliable to extract the latent sources underlying the brain activities but currently there is no recognized biomarker for mental disorders. Recent studies have identified alterations in the so called default mode network (DMN) that are common to several neuropsychiatric disorders, including schizophrenia. In particular, here we account for the hypothesis that the alterations in the DMN activity can be effectively highlighted by analyzing the transient states between two different tasks. A set of fMRI data acquired from 18 subjects performing working memory tasks is investigated for such purpose. Subjects are patients affected by schizophrenia for one half and healthy control subjects for the other. Under these conditions, the proposed methodology provides high discrimination performances in terms of classification error, thereby providing promising results for a preliminary tool able to monitor the disease state or to perform a prescreening for patients at risk for schizophrenia. © 2014 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 24, 239–248, 2014     

Modelling multivalent defects in thin film solar cells

Multivalent defects, e.g. double donors/acceptors or amphoteric defects, are important in materials used in solar cell production in general and in chalcopyrite materials in particular. We extended our thin film solar cell simulation software scaps to enable the simulation of multivalent defects with up to five different charge states; the algorithms presented are however able to simulate an arbitrary number of possible charge states. The presented solution method avoids numerical inaccuracies caused by the subtraction of two almost equal numbers.This new modelling facility is afterwards used to investigate the consequences of the multivalent character of defects for the simulation of chalcopyrite based solar cells.     

Doppler centroid estimation for ScanSAR data

We introduce a novel accurate technique to estimate the Doppler centroid (DC) in ScanSAR missions. The technique starts from the ambiguous DC measures in the subswaths and uses a method alternative to standard unwrapping to undo the jumps in estimates induced by modulo pulse repetition frequency (PRF) measures. The proposed alternative is less error prone than the usual unwrapping techniques. Doppler Ambiguity is then solved by implementing a maximum-likelihood estimate that exploits the different PRFs used in different subswaths. An azimuth pointing of the antenna that does not change with subswaths, or that changes in a known way, is assumed. However, if the PRF diversity is strong enough, unknown small changes in azimuth pointing are tolerated and accurately estimated. This estimator is much simpler and more efficient, than those in the literature. Results achieved with both RADARSAT 1 and ENVISAT ScanSAR data are reported.     

Thiazole derivatives‐functionalized polyvinyl chloride nanocomposites with photostability and antimicrobial properties

Polyvinyl chloride (PVC) was modified via substitution reaction with 2‐aminothiazole and ethyl 2‐aminothiazole‐4‐carboxylate separately in the absence and in presence of silver (AgNPs) or copper (CuNPs) nanoparticles, using metal salts as precursors, in 3% (w/w) with respect to PVC. The functionalized PVC‐nanocomposites have been characterized via FTIR, ¹HNMR spectroscopic analyses, in addition to the morphological investigation such as scanning (SEM) and transmission electron microscopy (TEM). Spectral data confirmed the introduction of the thiazole (ester) to the PVC backbone. TEM analysis showed that the sizes of the AgNPs and CuNPs have fallen in the range of 10–30 nm and 30–50 nm for the prepared nanocomposites, respectively. Evaluating the photostability of modified nanocomposites was estimated by following the extent of discoloration for UV‐irradiated samples colorimetrically in accordance with the irradiation time. The antimicrobial activity of the modified nanocomposites was explored against three Gram+ve bacteria (Bacillus subtilis, Staphylococcus aureus, and Streptococcus faecalis), three Gram‐ve bacteria (Escherichia coli, Neisseria gonorrhoeae, and Pseudomonas aeruginosa), and two fungi (Candida albicans and Aspergillus flavus). Aminothiazole (ester)‐functionalized PVC exhibited significant antimicrobial efficiencies against the investigated pathogens. However, incorporation of AgNPs or CuNPs to the modified PVC enhanced their inhibitory effect against the microorganisms under investigation. J. VINYL ADDIT. TECHNOL., 25:E137–E146, 2019. © 2018 Society of Plastics Engineers