Fucoidan-loaded electrospun Polyvinyl-alcohol/Chitosan nanofibers with enhanced antibacterial activity for skin tissue engineering.

The polymeric nanofiber may interact and control certain regeneration processes at the molecular level to repair damaged tissues. This research focuses on the development of characterization and antibacterial capabilities of polyvinyl alcohol (PVA)/chitosan (CS) nanofibres containing fucoidan (FUC) for tissue engineering as a skin tissue substitute. A control group consisting of 13% PVA/(0.1)% CS nanofiber was prepared. To confer antibacterial properties to the nanofiber, 10, 20, and 30 mg of FUC were incorporated into this control group. The scanning electron microscope (SEM) proved the homogeneous and beadless structures of the nanofibers. The antibacterial activity of the 13% PVA/(0.1)% CS/(10, 20, 30) FUC was tested against the S.aureus and E.coli and the results showed that with FUC addition, the antibacterial activities of the nanofibers increased. The biocompatibility test was performed with a fibroblast cell line for 1, 3, and 7 days of incubation and the results demonstrated that FUC addition enhanced the bioactivity of the 13% PVA/(0.1)% CS nanofibers. In addition, the biocompatibility results showed that 13% PVA/(0.1)% CS/10 FUC had the highest viability value for all incubation periods compared to the others. In addition, the tensile test results showed that; the maximum tensile strength value was observed for 13% PVA/(0.1)% CS/10 FUC nanofibers.

Impact of nanotechnology on conventional and artificial intelligence-based biosensing strategies for the detection of viruses.

Recent years have witnessed the emergence of several viruses and other pathogens. Some of these infectious diseases have spread globally, resulting in pandemics. Although biosensors of various types have been utilized for virus detection, their limited sensitivity remains an issue. Therefore, the development of better diagnostic tools that facilitate the more efficient detection of viruses and other pathogens has become important. Nanotechnology has been recognized as a powerful tool for the detection of viruses, and it is expected to change the landscape of virus detection and analysis. Recently, nanomaterials have gained enormous attention for their value in improving biosensor performance owing to their high surface-to-volume ratio and quantum size effects. This article reviews the impact of nanotechnology on the design, development, and performance of sensors for the detection of viruses. Special attention has been paid to nanoscale materials, various types of nanobiosensors, the internet of medical things, and artificial intelligence-based viral diagnostic techniques.

Development of Satureja cuneifolia-loaded sodium alginate/polyethylene glycol scaffolds produced by 3D-printing technology as a diabetic wound dressing material.

Acute wounds are a common health problem, with millions of people affected and decreased granulation tissue formation and vascularization, it is also a big challenge for wound care researchers to promote acute wound healing around the globe. This study aims to produce and characterize Satureja cuneifolia plant extract (SC)-blended with sodium alginate (SA) /polyethylene glycol (PEG) scaffolds for the potential treatment of diabetic ulcer. SA/PEG scaffolds were prepared by adding different concentrations (1, 3, and 5 wt%) of PEG to 9 wt% SA. The morphological and chemical composition of the resulting 3D printed composite scaffolds was determined using scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR), respectively. Mechanical and thermal properties, swelling, and degradation behaviours were also investigated. The release kinetics of SC were performed. The antimicrobial analysis was evaluated against Escherichia coli and Staphylococcus aureus strains. 3D printed scaffolds have shown an excellent antibacterial effect, especially against gram-positive bacteria due to the antibacterial SC extract they contain. Furthermore, the cell viability of fibroblast (L929) cells on/within scaffolds were determined by the colourimetric MTT assay. The SA/PEG/SC scaffolds show a great promising potential candidate for diabetic wound healing and against bacterial infections.

Development of Electrospun WE43 Magnesium Alloy-Like Compound.

Metallic structures are conventionally fabricated with high temperature/deformation processes resulting the smallest possible microscopic structures in the order of several hundreds of micrometer. Therefore, to obtain structures with fibers smaller than 100 µm, those are unsuitable. In this study, electrospinning, a fiber fabrication technique commonly used for polymers, was adopted to fabricate a WE43 magnesium alloy-like fibrous structure. The aim is to adopt metallic WE43 alloy to regenerative medicine using tissue engineering approach by mimicking its composition inside of a fibrous structure. The solution required for electrospinning was obtained with water soluble nitrates of elements in WE43 alloy, and PVP or PVA were added to obtain a spinnable viscosity which was pyrolised away during heat treatment. Electrospinning parameters were optimized with naked-eye observations and SEM as 1.5 g salts and 5 wt.% PVA containing solution prepared at 90 °C and electrospun under 30 kV from a distance of 12-15 cm with a feeding rate of 5 µl/min. Then the samples were subjected to a multi-step heat treatment under argon to remove the polymer and calcinate the nitrates into oxides which was designed based on thermal analyses and reaction kinetics calculations as 6 h at 230 °C, 8.5 h at 390 °C, 5 h at 465 °C, 80 h at 500 °C and 10 h at 505 °C, consecutively. The characterizations conducted in terms of structure, composition and crystallinity with XRD, XPS, EDX and SEM showed that it is possible to obtain MgaYbNdcZrdOx (empirical) fibers with the same composition as WE43 in sub-millimeter sizes using this approach.

Encapsulation of ß-Carotene by Emulsion Electrospraying Using Deep Eutectic Solvents.

The encapsulation ß-carotene in whey protein concentrate (WPC) capsules through the emulsion electrospraying technique was studied, using deep eutectic solvents (DES) as solvents. These novel solvents are characterized by negligible volatility, a liquid state far below 0 °C, a broad range of polarity, high solubilization power strength for a wide range of compounds, especially poorly water-soluble compounds, high extraction ability, and high stabilization ability for some natural products. Four DES formulations were used, based on mixtures of choline chloride with water, propanediol, glucose, glycerol, or butanediol. ß-Carotene was successfully encapsulated in a solubilized form within WPC capsules; as a DES formulation with choline chloride and butanediol, the formulation produced capsules with the highest carotenoid loading capacity. SEM micrographs demonstrated that round and smooth capsules with sizes around 2 µm were obtained. ATR-FTIR results showed the presence of DES in the WPC capsules, which indirectly anticipated the presence of ß-carotene in the WPC capsules. Stability against photo-oxidation studies confirmed the expected presence of the bioactive and revealed that solubilized ß-carotene loaded WPC capsules presented excellent photo-oxidation stability compared with free ß-carotene. The capsules developed here clearly show the significant potential of the combination of DES and electrospraying for the encapsulation and stabilization of highly insoluble bioactive compounds.

Synthesis and characterization of antibacterial drug loaded ß-tricalcium phosphate powders for bone engineering applications.

Powders of ß-tricalcium phosphate [ß-TCP, ß-Ca3(PO4)2] and composite powders of ß-TCP and polyvinyl alcohol (PVA) were synthesized by using wet precipitation methods. First, the conditions for the preparation of single phase ß-TCP have been delineated. In the co-precipitation procedure, calcium nitrate and diammonium hydrogen phosphate were used as calcium and phosphorous precursors, respectively. The pH of the system was varied in the range 7-11 by adding designed amounts of ammonia solution. The filtered cakes were desiccated at 80 °C and subsequently calcined at different temperatures in the range between 700-1100 °C. Later on, rifampicin form II was used to produce drug-loaded ß-TCP and PVA/ß-TCP powders. All the synthesized materials have been characterized from morphological (by scanning electron microscopy) and structural-chemical (by X-ray diffraction and Fourier transform infrared spectroscopy) point of view. The drug loading capacity of the selected pure ß-TCP powder has been assessed. The biological performance (cytocompatibility in fibroblast cell culture and antibacterial efficacy against Escherichia coli and Staphylococcus aureus) has been tested with promising results. Application perspectives of the designed drug-bioceramic-polymer blends are advanced and discussed.

Development of Poly(vinyl alcohol) (PVA)/Reduced Graphene Oxide (rGO) Electrospun Mats.

In this study, electrospun reduced graphene oxide (rGO) and poly(vinyl alcohol) (PVA) nanocomposites were developed with the concentration of rGO as 0.5 and 1.0 wt% by dispersing rGO in the PVA solution without using any co-solvent which may cause toxic effect for possible applications like packaging and tissue engineering. Water solubility of PVA was eliminated by UV-radiation crosslinking method. SEM analysis proved that continuous and bead-free nanofibers were obtained by electrospinning process and all electrospun mats had similar fiber characteristics with homogeneous fiber morphology. The average fiber diameter (nm), inter-fiber pore size (µm) and the porosity (%) were increased with rGO incorporation. Additionally, enhanced tensile properties was achieved by rGO addition as the highest tensile strength was obtained as ∼5 MPa for electrospun PVA + 1.0 wt% rGO nanocomposites. ATR-FTIR analyses showed that there was a relatively strong interfacial interaction between rGO and PVA. Moreover, the thermal stability of obtained nanocomposites was enhanced by rGO addition without changing the crystal structure of PVA proved by XRD analyses. Also, improved electrical conductivity of the nanocomposites was obtained by rGO content as the highest conductivity (∼11 µS · cm-1) was measured for electrospun PVA + 1.0 wt% rGO.

Electrospun Oxygen Scavenging Films of Poly(3-hydroxybutyrate) Containing Palladium Nanoparticles for Active Packaging Applications.

This paper reports on the development and characterization of oxygen scavenging films made of poly(3-hydroxybutyrate) (PHB) containing palladium nanoparticles (PdNPs) prepared by electrospinning followed by annealing treatment at 160 °C. The PdNPs were modified with the intention to optimize their dispersion and distribution in PHB by means of two different surfactants permitted for food contact applications, i.e., hexadecyltrimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS). Analysis of the morphology and characterization of the chemical, thermal, mechanical, and water and limonene vapor barrier properties and the oxygen scavenging capacity of the various PHB materials were carried out. From the results, it was seen that a better dispersion and distribution was obtained using CTAB as the dispersing aid. As a result, the PHB/PdNP nanocomposites containing CTAB provided also the best oxygen scavenging performance. These films offer a significant potential as new active coating or interlayer systems for application in the design of novel active food packaging structures.

Antibacterial Performance of PCL-Chitosan Core-Shell Scaffolds.

In this study, antibacterial performance of the coaxially electrospun Poly-ε-caprolactone (PCL)-chitosan core-shell scaffolds developed, optimized and identified physically and chemically in our previous study, were evaluated for the suitability in wound healing applications. The aim of utilizing a core-shell fibrous scaffold with PCL as core and chitosan as shell was to combine natural biocompatibility, biodegradability and antibacterial properties of chitosan with mechanical properties and resistance to enzymatic degradation of PCL. The scaffolds were prepared with the optimized parameters, obtained from our previous study. Thickness and contact angle measurements as well as Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses confirmed repeated fabrication of PCL-chitosan core-shell scaffolds. In this study, assays specific to wound dressing materials, such as water vapor transmission rate (WVTR), in vitro degradability and antibacterial tests were carried out. WVTR value of PCL-chitosan core-shell scaffolds was higher (2315 ± 3.4 g/m2 · day) compared to single PCL scaffolds (1654 ± 3.2 g/m2 · day) due to the higher inter-fiber pore size. Additionally, in vitro degradability assays showed that the susceptibility of chitosan to enzymatic degradation can be significantly improved by hybridization with more resistant PCL while still keeping the scaffold to be considered as biodegradable. Finally, inhibition ratio and inhibition zone measurements showed that the PCL-chitosan core-shell polymeric scaffolds had significant antibacterial performance (52.860 ± 2.298% and 49.333 ± 0.719% inhibition ratios; 13.975 ± 0.124 mm and 12.117 ± 0.133 mm clear inhibition zones, against E. coli and S. aureus, respectively), close to the native chitosan. Therefore, the developed scaffolds can be considered as suitable candidates for biodegradable wound dressing applications.

Development of Antibacterial Composite Electrospun Chitosan-Coated Polypropylene Materials.

In this study, a natural antibacterial substance chitosan was coated with/without potassium sorbate (KS) (0.8% (w/w) of KS, 8% (w/v) chitosan) onto the polypropylene (PP) film by using electrospinning technique to obtain novel antibacterial composite materials for various applications such as wound dressing, tissue engineering, drug delivery and food packaging. Atmospheric pressure plasma surface treatment was applied onto polypropylene films in order to increase its wettability thus enhancing the adhesion capacity of the films and the optimum CA value was determined as 42.75 ± 0.80°. Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS) analyses were realized to observe the morphological changes and chemical properties of the samples, respectively. Contact angle measurements, tensile testing, oxygen and water vapor transmission rate analyses were performed to obtain wettability values, mechanical properties and WVTRs, respectively. The WVTR was increased by plasma treatment and addition of KS (from 14.264 ± 0.214% to 21.020 ± 0.659%). The desired antibacterial performance of the samples was assessed with Staphylococcus aureus and Escherichia coli by inhibition ratio calculation and disc diffusion assay. The highest inhibition ratios were found as 64% for S. aureus and 92% for E. coli for plasma-treated CS-KS-PP films.

Novel hybrid scaffolds for the cultivation of osteoblast cells.

In this study, natural biodegradable polysaccharide, chitosan, and synthetic biodegradable polymer, poly(ɛ-caprolactone) (PCL) were used to prepare 3D, hybrid polymeric tissue scaffolds (PCL/chitosan blend and PCL/chitosan/PCL layer by layer scaffolds) by using the electrospinning technique. The hybrid scaffolds were developed through HA addition to accelerate osteoblast cell growth. Characteristic examinations of the scaffolds were performed by micrometer, SEM, contact angle measurement system, ATR-FTIR, tensile machine and swelling experiments. The thickness of all electrospun scaffolds was determined in the range of 0.010±0.001-0.012±0.002 mm. In order to optimize electrospinning processes, suitable bead-free and uniform scaffolds were selected by using SEM images. Blending of PCL with chitosan resulted in better hydrophilicity for the PCL/chitosan scaffolds. The characteristic peaks of PCL and chitosan in the blend and layer by layer nanofibers were observed. The PCL/chitosan/PCL layer by layer structure had higher elastic modulus and tensile strength values than both individual PCL and chitosan structures. The layer by layer scaffolds exhibited the PBS absorption values of 184.2; 197.2% which were higher than those of PCL scaffolds but lower than those of PCL/chitosan blend scaffolds. SaOs-2 osteosarcoma cell culture studies showed that the highest ALP activities belonged to novel PCL/chitosan/PCL layer by layer scaffolds meaning better cell differentiation on the surfaces.

Water/O2-plasma-assisted treatment of PCL membranes for biosignal immobilization.

The main purpose of this study was to obtain COOH functionalities on the surface of poly-epsilon-caprolactone (PCL) membranes using low-pressure water/O(2)-plasma-assisted treatment. PCL membranes were prepared using the solvent-casting technique. Then, low-pressure water/O(2) plasma treatments were performed in a cylindrical, capacitively coupled RF-plasma-reactor in three steps: H(2)O/O(2)-plasma treatment; in situ (oxalyl chloride vapors) gas/solid reaction to convert -OH functionalities into -COCl groups; and hydrolysis for final -COOH functionalities. Optimization of plasma modification processes was done using the DoE software program. COOH and OH functionalities on modified surfaces were detected quantitatively using the fluorescent labeling technique and an UVX 300G sensor. Chemical structural information of untreated, plasma treated and oxalyl chloride functionalized PCL membranes were acquired using pyrolysis GC/MS and ESCA analysis. High-resolution AFM images revealed that nanopatterns were more affected than micropatterns by plasma treatments. AFM images recorded with amino-functionalized tips presented increased size of the features on the surface that suggests higher density of the carboxyls on the nanotopographical elements. Low-pressure water/O(2)-plasma-treated and oxalyl chloride functionalized samples were biologically activated with insulin and/or heparin biosignal molecules using a PEO (polyoxyethylene bis amine) spacer. The success of the immobilization process was checked qualitatively by ESCA analysis. In addition, fluorescent labeling techniques were used for the quantitative determination of immobilized biomolecules. Cell-culture experiments indicated that biomolecule immobilization onto PCL scaffolds was effective on L929 cell adhesion and proliferation, especially in the presence of heparin.

Comparison of cellular proliferation on dense and porous PCL scaffolds.

In this contribution, PCL (poly-epsilon caprolactone) scaffolds were prepared by solvent-casting/particle-leaching technique in the presence of two pore formers, PEG(4000) or sucrose molecules in different quantities (0, 10, 20, 30, 40, 50, 55 w/w% PEG(4000)/PCL; 10, 20 w/w% Sucrose/PCL). The surface and bulk properties of the resulting scaffolds were studied by SEM, DSC and FTIR. SEM photographs showed that, macroporosity was obtained in the PCL structures prepared with sucrose crystals while microporous structure was obtained in the presence of PEG(4000) molecules. Average pore diameters calculated from SEM photographs were 40.1 and 191.2 mum for 40% PEG(4000)/PCL and 10% Sucrose/PCL scaffolds, respectively. The DSC and FTIR results confirmed that there is no any interaction between pore formers and PCL during structural formation, and both pore formers, PEG(4000) and sucrose, remained independently in the scaffolds. L929 mouse fibroblast cells were seeded onto PCL structures and maintained during 7 days to evaluate cell proliferation. Cell culture results showed that, 10% Sucrose/PCL scaffold was the most promising substrate for L929 cell growth due to 3-D architecture and macroporous structure of the scaffold.