Porous Bilayer Vascular Grafts Fabricated from Electrospinning of the Recombinant Human Collagen (RHC) Peptide-Based Blend

Cardiovascular diseases, including coronary artery and peripheral vascular pathologies, are leading causes of mortality. As an alternative to autografts, prosthetic grafts have been developed to reduce the death rate. This study presents the development and characterization of bilayer vascular grafts with appropriate structural and biocompatibility properties. A polymer blend of recombinant human collagen (RHC) peptides and polycaprolactone (PCL) was used to build the inner layer of the graft by electrospinning and co-electrospinning the water-soluble polyethylene oxide (PEO) as sacrificial material together with PCL to generate the porous outer layer. The mechanical test demonstrated the bilayer scaffold’s appropriate mechanical properties as compared with the native vascular structure. Human umbilical vein endothelial cells (HUVEC) showed enhanced adhesion to the lumen after seeding on nanoscale fibers. Meanwhile, by enhancing the porosity of the microfibrous outer layer through the removal of PEO fibers, rat smooth muscle cells (A7r5) could proliferate and infiltrate the porous layer easily.

Electrochemical Synthesis of Nano-Sized Silicon from KCl–K2SiF6 Melts for Powerful Lithium-Ion Batteries

Currently, silicon and silicon-based composite materials are widely used in microelectronics and solar energy devices. At the same time, silicon in the form of nanoscale fibers and various particles morphology is required for lithium-ion batteries with increased capacity. In this work, we studied the electrolytic production of nanosized silicon from low-fluoride KCl–K2SiF6 and KCl–K2SiF6–SiO2 melts. The effect of SiO2 addition on the morphology and composition of electrolytic silicon deposits was studied under the conditions of potentiostatic electrolysis (cathode overvoltage of 0.1, 0.15, and 0.25 V vs. the potential of a quasi-reference electrode). The obtained silicon deposits were separated from the electrolyte residues, analyzed by scanning electron microscopy and spectral analysis, and then used to fabricate a composite Si/C anode for a lithium-ion battery. The energy characteristics of the manufactured anode half-cells were measured by the galvanostatic cycling method. Cycling revealed better capacity retention and higher coulombic efficiency of the Si/C composite based on silicon synthesized from KCl–K2SiF6–SiO2 melt. After 15 cycles at 200 mA·g−1, material obtained at 0.15 V overvoltage demonstrates capacity of 850 mAh·g−1.

Electro-Spinning and Electro-Spraying as Innovative Approaches in Developing of a Suitable Food Vehicle for Polyphenols-Based Functional Ingredients

With recent advances in medical and nutrition sciences, functional foods and nutraceuticals fortified with natural polyphenols have received a lot of attention from both health professionals and the common population in the last few years since their chemical structure allows them to exert various health effects (e.g., antioxidant, anti-inflammatory, immune, antitumor and prebiotic properties). Nonetheless, there are several hurdles to applications of polyphenols in the food system. The most critical hurdle includes polyphenols’ tendency to lose their anti-oxidative properties or bioactive functionalities during food processing, as well as inclusion of poly-phenol compounds may impart an astringent or bitter taste, or introduce a degree of brown coloring causing serious sensorial impacts on food products. On this basis, interest has increased in understanding the development of new and efficient food vehicles as delivery systems for polyphenols-based functional ingredients. In this context, one approach that could augment the growth of polyphenols-based functional foods is electro-hydrodynamic processing, as the most versatile method to produce nanoscale fibers or particulates suitable for application in food technology by encapsulation to form nanoscale delivery systems.

Innovative Nanotechnology a Boon for Fight Against Pandemic COVID–19

COVID – 19 is a contagious disease caused by severe acute respiratory syndrome (SARS-CoV2). The rate at which COVID – 19-virus spread from epidemic to pandemic within a short period is quite alarming. As of July 2020, the Dashboard of the World Health Organization (WHO) recorded over 15 million COVID – 19 cases across 213 countries, with mortality of over 620,000. The governments and healthcare agencies responsible for mitigating the virus's spread have adopted several strategies to end the pandemic. However, all hands were on deck to establish the standard treatment modalities of SARS-CoV-2 through inventing new drugs, vaccine candidates, or repurposing the existing medicines and robust diagnostic tools, in addition to other technological innovations. Therefore, nanotechnology’s employment would play a vital role in bringing multidisciplinary ways of developing affordable, reliable, and powerful tools for diagnosis, in addition to personal protection and effective medicines. Additionally, nanosensors' application would significantly aid the diagnoses of the COVID–19 even on asymptomatic patients, and thus would be an essential means for determining its prevalence. Likewise, nanoscale fibers can optimize personal equipment protection and allow their reusability for medical and economic benefits. Accordingly, the literature was intensively reviewed by searching for the combinations of the research keywords in the official scientific databases such as Science Direct, PubMed, and Google Scholar. Hence, this research highlighted the perspective contributions of nanotechnology in the war against the COVID-19 pandemic.

Effect of Electrospinning Parameters on the Fiber Diameter and Morphology of PLGA Nanofibers

Background: Poly lactic-co-glycolic acid (PLGA) has been widely investigated for various biomedical applications, such as craniofacial bone regeneration, wound dressing and tissue engineering. Electrospinning is a versatile technology used to produce micro/nanoscale fibers with large specific surface area and high porosity. Purpose: The aim of the current study is to prepare PLGA nanofibers using electrospinning for guided tissue regeneration/guided bone regeneration applications. The objective of this study is to determine the appropriate electrospinning parameters such as applied voltage, flow rate, spinneret-collector distance and polymer solution concentration for preparation of PLGA fibrous membrane and their effect on the mean fiber diameter of the electrospun fibers. Method: PLGA pellets were dissolved in Hexafluoroisopropanol (HFIP) in various concentrations overnight using a bench rocker. The resulting PLGA solution was then loaded into a syringe and electrospinning was done by maintaining the other parameters constant. Similarly, various fibrous mats were collected by altering the specific electrospinning parameter inputs such as applied voltage, flow rate and spinneret-collector distance. The morphology of the fibrous mats was characterized using Scanning Electron Microscope. The mean fiber diameter was assessed using ImageJ software and the results were compared using one-way ANOVA. Results: We obtained bead-free uniform fibers with various tested solution concentrations. One-way ANOVA analysis demonstrated significant variation in mean fiber diameter of the electrospun fibers with altering applied voltage, solution concentration, flow rate and spinneret-collector distance. Conclusion: The above-mentioned electrospinning parameters and solution concentration influence the mean fiber diameter of electrospun PLGA nanofibers.

A Practicable Measurement Strategy for Compliance Checking Number Concentrations of Airborne Nano- and Microscale Fibers

Despite compelling reports on asbestos-like pathogenicity, regulatory bodies have been hesitant to implement fiber number-based exposure limits for biodurable nanoscale fibers. One reason has been the lack of a practicable strategy for assessing airborne fiber number concentrations. Here, a method is proposed, detailed and tested for compliance checking concentrations of airborne nano- and microscale fibers. It relies on Poisson statistical significance testing of the observed versus a predicted number of fibers on filters that have sampled a known volume of aerosol. The prediction is based on the exposure concentration to test. Analogous to the established counting rules for WHO-fibers, which use a phase contrast microscopy-related visibility criterion of 200 nm, the new method also introduces a cut-off diameter, now at 20 nm, which is motivated by toxicological findings on multi-walled carbon nanotubes. This cut-off already reduces the workload by a factor of 400 compared to that necessary for imaging, detecting and counting nanofibers down to 1 nm in diameter. Together with waiving any attempt to absolutely quantify fiber concentrations, a compliance check at the limit-of-detection results in an analytical workload that renders our new approach practicable. The proposed method was applied to compliance checking in 14 very different workplaces that handled or machined nanofiber-containing materials. It achieved detecting violations of the German benchmark exposure level of 10,000 nanofibers per cubic meter.

Development and Evaluation of Thermally-Crosslinked Mucoadhesive GantrezTM S-97/Polyvinyl Alcohol/ Hyaluronic Acid-Catechol Nanofibers

This study aimed to develop novel thermally crosslinked mucoadhesive nanofibers. The nanofiber patches were composed of mucoadhesive polymers which were catechol-bearing hyaluronic acid (HA-cat) and copolymer of methyl vinyl ether and maleic anhydride (GantrezTM, GT). Polyvinyl alcohol was used to improve the nanofiber properties. The nanofibers were prepared from a polymer mixture of 20 %wt GT, 10 %wt PVA, and 2 %wt HA-cat at different ratios using an electrospinning technique. Crosslinking process was performed by heat treatment at 130 °C for various durations. The appearances and chemical characteristics of the patch was evaluated using scanning electron microscope (SEM) and attenuated total reflectance Fourier-transformed infrared spectroscopy (ATR-FTIR), respectively. Moreover, the percentage of water insolubilization, tensile strength, and mucoadhesive property of the electrospun nanofibers were evaluated. Different polymer ratios provided identical nanoscale fibers. The patch prepared at the GT:PVA:HA-cat ration of 1:1:2 which provided the highest amount of catechol was selected. The optimal crosslinking time was 2 h under 130 °C in which the fiber diameters were not altered, and the highest percentage of water insolubilization was observed. Hydrogen and ester bond formation were established from the ATR-FTIR spectrum of the crosslinked patch. The patch could resist the force applied up to 4.82±0.46 N prior to deformation. In addition, the maximum detachment force from porcine buccal mucosa was 0.08±0.01 N. After all, the prepared electrospun mucoadhesive nanofibers may be a favorable mucoadhesive material for transmucosal drug delivery.

The Importance of a Filament-like Structure in Aerial Dispersal and the Rarefaction Effect of Air Molecules on a Nanoscale Fiber: Detailed Physics in Spiders’ Ballooning

Synopsis Many flying insects utilize a membranous structure for flight, which is known as a “wing.” However, some spiders use silk fibers for their aerial dispersal. It is well known that spiders can disperse over hundreds of kilometers and rise several kilometers above the ground in this way. However, little is known about the ballooning mechanisms of spiders, owing to the lack of quantitative data. Recently, Cho et al. discovered previously unknown information on the types and physical properties of spiders’ ballooning silks. According to the data, a crab spider weighing 20 mg spins 50–60 ballooning silks simultaneously, which are about 200 nm thick and 3.22 m long for their flight. Based on these physical dimensions of ballooning silks, the significance of these filament-like structures is explained by a theoretical analysis reviewing the fluid-dynamics of an anisotropic particle (like a filament or a high-slender body). (1) The filament-like structure is materially efficient geometry to produce (or harvest, in the case of passive flight) fluid-dynamic force in a low Reynolds number flow regime. (2) Multiple nanoscale fibers are the result of the physical characteristics of a thin fiber, the drag of which is proportional to its length but not to its diameter. Because of this nonlinear characteristic of a fiber, spinning multiple thin ballooning fibers is, for spiders, a better way to produce drag forces than spinning a single thick spider silk, because spiders can maximize their drag on the ballooning fibers using the same amount of silk dope. (3) The mean thickness of fibers, 200 nm, is constrained by the mechanical strength of the ballooning fibers and the rarefaction effect of air molecules on a nanoscale fiber, because the slip condition on a fiber could predominate if the thickness of the fiber becomes thinner than 100 nm.

INTERVENTION OF NOVEL NANOTECHNOLOGY IN FIGHT AGAINST COVID 19

The outbreak of pandemic COVID-19 mounts overall pressure on healthcare and modern societies. The intervention of nanotechnology will play a vital role in bringing multi-disciplinary ways of developing affordable, reliable, and powerful tools for diagnosis, personal protection, and new effective medicines. Moreover, employing nanosensors will significantly aid to diagnose the viruses even on asymptomatic patients. Likewise, the use of nanoscale fibers can optimize the protection affinity of personal protective equipment and facemasks and allows their reusability for medical and economical benefit. This research was designed purposely to highlight the perspective contributions of nanotechnology in the war against COVID-19 pandemic

Highly wet aqueous foams stabilized by an amphiphilic bio-based hydrogelator derived from dehydroabietic acid

Highly wet aqueous foams are stabilized by a rosin-based surfactant which can form nanoscale fibers in the liquid films of bubbles.