Development of highly bacterial filtration efficient and antibacterial cellulose acetate/gum rosin composite nanofibers for facemask application

Cellulose acetate (CA) is a non-toxic, renewable, and biodegradable polymeric material that can be effectively electrospuned into bacterial filtration efficient nanofiber membrane for face mask application. However, its fragile and non-antibacterial nature influenced its scalability. In this context, natural antibacterial gum rosin (GR) additive can be explored. Therefore, the present study aimed to produce a CA/GR composite nanofibers membrane for the finest bacterial filtration, excellent antibacterial moiety, and improved tensile properties for facemask application. Hence, in this work, we have studied the effect of GR concentrations (0-15 g) on the needleless electrospinning behavior and fibers' morphology through rheology, electrical conductivity, and SEM analysis. These analyses revealed that GR significantly affects the fibers' spinning behavior, morphology, and diameter of the produced fibers. Later, ATR-FTIR spectroscopy mapped the functional changes in the produced nanofibers that affirmed the integration of GR with CA polymer. This modification resulted in a 3-fold rise in tensile strength and an 11-fold decline in elongation% in 15 g CA/GR composite nanofibers membrane than the control sample. Furthermore, it has shown 98.79 ± 0.10% bacterial filtration efficiency and ∼ 93 % reduction in Staphylococcus Aureus and Klebsiella Pneumoniae bacterial growth, elucidating a high-efficiency level for potential facemask application.

Electrospun Chitosan-Based Nanofibrous Coating for the Local and Sustained Release of Vancomycin

As the population ages, the number of vascular surgery procedures performed increases. Older adults often have multiple comorbidities, such as diabetes and hypertension, that increase the risk of complications from vascular surgery including vascular graft infection (VGI). VGI is a serious complication with significant morbidity, mortality, and healthcare costs. Here, we aimed to develop a nanofibrous chitosan-based coating for vascular grafts loaded with different concentrations of the vancomycin antibiotic vancomycin (VAN). Blending chitosan with poly(vinyl alcohol) or poly(ethylene oxide) copolymers improved solubility and ease of spinning. Thermal gravimetric analysis and Fourier transform infrared spectroscopy confirmed the presence of VAN in the nanofibrous membranes. Kinetics of VAN release from the nanofibrous mats were evaluated using high-performance liquid chromatography, showing a burst followed by sustained release over 24 h. To achieve longer sustained release, a poly(lactic-co-glycolic acid) coating was applied, resulting in extended release of up to 7 days. Biocompatibility assessment using human umbilical vein endothelial cells demonstrated successful attachment and viability of the nanofiber patches. Our study provides insights into the development of a drug delivery system for vascular grafts aimed at preventing infection during implantation, highlighting the potential of electrospinning as a promising technique in the field of vascular surgery.

PVA-Based Electrospun Materials-A Promising Route to Designing Nanofiber Mats with Desired Morphological Shape-A Review

Poly(vinyl alcohol) is one of the most attractive polymers with a wide range of uses because of its water solubility, biocompatibility, low toxicity, good mechanical properties, and relatively low cost. This review article focuses on recent advances in poly(vinyl alcohol) electrospinning and summarizes parameters of the process (voltage, distance, flow rate, and collector), solution (molecular weight and concentration), and ambient (humidity and temperature) in order to comprehend the influence on the structural, mechanical, and chemical properties of poly(vinyl alcohol)-based electrospun matrices. The importance of poly(vinyl alcohol) electrospinning in biomedical applications is emphasized by exploring a literature review on biomedical applications including wound dressings, drug delivery, tissue engineering, and biosensors. The study also highlights a new promising area of particles formation through the electrospraying of poly(vinyl alcohol). The limitations and advantages of working with different poly(vinyl alcohol) matrices are reviewed, and some recommendations for the future are made to advance this field of study.

Drug Delivery Systems for Localized Cancer Combination Therapy

With over 2 million cancer cases and over 600,000 cancer-associated deaths predicted in the U.S. for 2022, this life-debilitating disease continuously impacts the lives of people across the nation every day. Therapeutic treatment options for cancer have historically involved chemotherapies to eradicate tumors with cytotoxic mechanisms which can negatively affect the efficacy versus toxicity ratio of treatment. With a need for more directed and therapeutically active options, targeted small-molecule inhibitors and immunotherapies have since emerged to mitigate treatment-associated toxicities. However, aggressive tumors can employ a wide range of defense mechanisms to evade monotherapy treatment altogether, resulting in the recurrence of therapeutically resistant tumors. Therefore, many clinical routines have included combination therapy in which anticancer agents are combined to provide a synergistic attack on tumors. Even with this approach, maximizing the efficacy of cancer treatment is contingent upon the dose of drug that reaches the site of the tumor, so often therapy is administered at the site of a tumor via localized delivery platforms. Commonly used platforms for localized drug delivery include polymeric wafers, nanofibrous scaffolds, and hydrogels where drug combinations can be loaded and delivered synchronously. Attaining synergistic activity from these localized systems is dependent on proper material selection and fabrication methods. Herein, we describe these important considerations for enhancing the efficacy of cancer combination therapy through biodegradable, localized delivery systems.

Polybutylene Succinate Processing and Evaluation as a Micro Fibrous Graft for Tissue Engineering Applications

A microfibrous tubular scaffold has been designed and fabricated by electrospinning using poly (1,4-butylene succinate) as biocompatible and biodegradable material. The scaffold morphology was optimized as a small diameter and micro-porous conduit, able to foster cell integration, adhesion, and growth while avoiding cell infiltration through the graft's wall. Scaffold morphology and mechanical properties were explored and compared to those of native conduits. Scaffolds were then seeded with adult normal human dermal fibroblasts to evaluate cytocompatibility in vitro. Haemolytic effect was evaluated upon incubation with diluted whole blood. The scaffold showed no delamination, and mechanical properties were in the physiological range for tubular conduits: elastic modulus (17.5 ± 1.6 MPa), ultimate tensile stress (3.95 ± 0.17 MPa), strain to failure (57 ± 4.5%) and suture retention force (2.65 ± 0.32 N). The shown degradation profile allows the graft to provide initial mechanical support and functionality while being colonized and then replaced by the host cells. This combination of features might represent a step toward future research on PBS as a biomaterial to produce scaffolds that provide structure and function over time and support host cell remodelling.

Electrospun Poly (Vinyl Alcohol) Nanofibrous Mat Loaded with Green Propolis Extract, Chitosan and Nystatin as an Innovative Wound Dressing Material

Purposes

The objective of this work was to produce and characterise biodegradable poly (vinyl alcohol) (PVA) nanofibre loaded with green propolis extract (GPE), chitosan (CS) and nystatin (NYS) alone and in mixtures as a potential wound dressing material.

Methods

The GPE, NYS and CS1% were loaded in electrospinning compositions based on PVA 7%, 8% and 12% solubilised in milli-Q water or a mixture of water and glacial acetic acid. The electrospinning compositions without actives (blank) and those loaded with actives were characterised by determining the pH, electrical conductivity and rheological properties. An image analysis procedure applied to photomicrographs obtained by scanning electronic microscopy (SEM) allowed the determination of the nanofibres' diameter distribution and average surface porosity. The disintegration time and swelling ratio of the nanofibre mats were also determined.

Results

The physicochemical parameters of the electrospinning compositions (pH, electrical conductivity and rheology) and the incorporated active ingredients (GPE, CS and NYS) affected the electrospun nanofibre mats properties. The electrospun nanofibres' mean diameters and surface porosity ranged from 151.5 to 684.5 nm and from 0.29 ± 0.04 to 0.50 ± 0.05. The PVA/CS electrospun nanofibres fibres exhibited the smallest diameters, high surface porosity, water absorption capacity and disintegration time. The characteristics of the PVA/CS nanofibres mat associated with the biodegradability of the polymers make them a novel material with the potential to be applied as wound and burn dressings.

Dual Properties of Polyvinyl Alcohol-Based Magnetorheological Plastomer with Different Ratio of DMSO/Water

Polyvinyl alcohol (PVA)-based magnetorheological plastomer (MRP) possesses excellent magnetically dependent mechanical properties such as the magnetorheological effect (MR effect) when exposed to an external magnetic field. PVA-based MRP also shows a shear stiffening (ST) effect, which is very beneficial in fabricating pressure sensor. Thus, it can automatically respond to external stimuli such as shear force without the magnetic field. The dual properties of PVA-based MRP mainly on the ST and MR effect are rarely reported. Therefore, this work empirically investigates the dual properties of this smart material under the influence of different solvent compositions (20:80, 40:60, 60:40, and 80:20) by varying the ratios of binary solvent mixture (dimethyl sulfoxide (DMSO) to water). Upon applying a shear stress with excitation frequencies from 0.01 to 10 Hz, the storage modulus (G′) for PVA-based MRP with DMSO to water ratio of 20:40 increases from 6.62 × 10⁻⁵ to 0.035 MPa. This result demonstrates an excellent ST effect with the relative shear stiffening effect (RSTE) up to 52,827%. In addition, both the ST and MR effect show a downward trend with increasing DMSO content to water. Notably, the physical state of hydrogel MRP could be changed with different solvent ratios either in the liquid-like or solid-like state. On the other hand, a transient stepwise experiment showed that the solvent’s composition had a positive effect on the arrangement of CIPs within the matrix as a function of the external magnetic field. Therefore, the solvent ratio (DMSO/water) can influence both ST and MR effects of hydrogel MRP, which need to be emphasized in the fabrication of hydrogel MRP for appropriate applications primarily with soft sensors and actuators for dynamic motion control.

Solvent Dependence of the Rheological Properties in Hydrogel Magnetorheological Plastomer

Chemically crosslinked hydrogel magnetorheological (MR) plastomer (MRP) embedded with carbonyl iron particles (CIPs) exhibits excellent magnetic performance (MR effect) in the presence of external stimuli especially magnetic field. However, oxidation and desiccation in hydrogel MRP due to a large amount of water content as a dispersing phase would limit its usage for long-term applications, especially in industrial engineering. In this study, different solvents such as dimethyl sulfoxide (DMSO) are also used to prepare polyvinyl alcohol (PVA) hydrogel MRP. Thus, to understand the dynamic viscoelastic properties of hydrogel MRP, three different samples with different solvents: water, DMSO, and their binary mixtures (DMSO/water) were prepared and systematically carried out using the oscillatory shear. The outcomes demonstrate that the PVA hydrogel MRP prepared from precursor gel with water shows the highest MR effect of 15,544% among the PVA hydrogel MRPs. However, the samples exhibit less stability and tend to oxidise after a month. Meanwhile, the samples with binary mixtures (DMSO/water) show an acceptable MR effect of 11,024% with good stability and no CIPs oxidation. Otherwise, the sample with DMSO has the lowest MR effect of 7049% and less stable compared to the binary solvent samples. This confirms that the utilisation of DMSO as a new solvent affects the rheological properties and stability of the samples.

Hydrogen-Bonded, Mechanically Strong Nanofibers with Tunable Antioxidant Activity

We report on mechanically strong, water-insoluble hydrogen-bonded nanofiber mats composed of a hydrophilic polymer and a natural polyphenol that exhibit prolonged antioxidant activity. The high performance of fibrous mats resulted from the formation of a network of hydrogen bonds between a low-molecular-weight polyphenol (tannic acid, TA) and a water-soluble polymer (polyvinylpyrrolidone, PVP) and could be precisely controlled by the TA-to-PVP ratio. Dramatic enhancement (5- to 10-fold) in tensile strength, toughness, and Young's moduli of the PVP/TA fiber mats (as compared to those of pristine PVP fibers) was achieved at the maximum density of hydrogen bonds, which occurred at ∼0.2-0.4 molar fractions of TA. The formation of hydrogen bonds was confirmed by an increase in the glass-transition temperature of the polymer after binding with TA. When exposed to water, the fibers exhibited composition- and pH-dependent stabilities, with the TA-enriched fibers fully preserving their integrity in acidic and neutral media. Importantly, the fiber mats exhibited strong antioxidant activity with dual (burst and prolonged) activity profiles, which could be controlled via fiber composition, a feature useful for controlling radical-scavenging rates in environmental and biological applications.

Innovative Poly (Vinylidene Fluoride) (PVDF) Electrospun Nanofiber Membrane Preparation Using DMSO as a Low Toxicity Solvent

Electrospinning is an emerging technique for the preparation of electrospun fiber membranes (ENMs), and a very promising one on the basis of the high-yield and the scalability of the process according to a process intensification strategy. Most of the research reported in the literature has been focused on the preparation of poly (vinylidene fluoride) (PVDF) ENMs by using N,N- dimethylformamide (DMF) as a solvent, which is considered a mutagenic and cancerogenic substance. Hence, the possibility of using alternative solvents represents an interesting approach to investigate. In this work, we explored the use of dimethyl sulfoxide (DMSO) as a low toxicity solvent in a mixture with acetone for the preparation of PVDF-ENMs. As a first step, a solubility study of the polymer, PVDF 6012 Solef®, in several DMSO/acetone mixtures was carried out, and then, different operating conditions (e.g., applied voltage and needle to collector plate distance) for the successful electrospinning of the ENMs were evaluated. The study provided evidence of the crucial role of solution conductivity in the electrospinning phase and the thermal post-treatment. The prepared ENMs were characterized by evaluating the morphology (by SEM), pore-size, porosity, surface properties, and performance in terms of water permeability. The obtained results showed the possibility of producing ENMs in a more sustainable way, with a pore size in the range of 0.2-0.8 µm, high porosity (above 80%), and water flux in the range of 11.000-38.000 L/m²·h·bar.

3D-Printed Solid Dispersion Drug Products

With the well-known advantages of additive manufacturing methods such as three-dimensional (3D) printing in drug delivery, it is disappointing that only one product has been successful in achieving regulatory approval in the past few years. Further research and development is required in this area to introduce more 3D printed products into the market. Our study investigates the potential of fixed dose combination solid dispersion drug products generated via 3D printing. Two model drugs-fluorescein sodium (FS) and 5-aminosalicyclic acid (5-ASA)-were impregnated onto a polyvinyl alcohol (PVA) filament, and the influence of solvent choice in optimal drug loading as well as other influences such as the physicochemical and mechanical properties of the resultant filaments were investigated prior to development of the resultant drug products. Key outcomes of this work included the improvement of filament drug loading by one- to threefold due to solvent choice on the basis of its polarity and the generation of a 3D-printed product confirmed to be a solid dispersion fixed dose combination with the two model drugs exhibiting favourable in vitro dissolution characteristics.

Biocompatible polyvinyl alcohol and RISUG® blend polymeric films with spermicidal potential

Majority of the commercially available vaginal contraceptives encompasses cervicovaginal membrane disrupting detergent molecules as pharmacologically active ingredients. Development of a tissue-compatible vaginal contraceptive agent is necessary to circumvent the existing demand for female contraception in the reproductive healthcare sector. With this objective, the present study delineates the use of RISUG^® based non-hormonal female contraceptive films. RISUG^® was blended with polyvinyl alcohol (PVOH) to formulate biodegradable intra-vaginal contraceptive films. The formulated films were characterized for their thermal, physiochemical and biological features. The results showed that both RISUG^® and PVOH were miscible and interacted at the intermolecular level. Variations in the concentration of RISUG^® resulted in the changes in physicochemical, thermal and rheological characteristics of the formulated blends. In vitro toxicological assay of the polymeric formulations did not show any significant toxicity. However, the blend films retained spermicidal potential of RISUG^®. Furthermore, in vivo toxicological evaluation of the polymeric blend in the rat model revealed about their biocompatibility with no significant organ toxicity, hematological and biochemical alterations. These results together confirm the potential applicability of the PVOH:RISUG^® blend films as a vaginal contraceptive.

Ultraporous Membranes Electrospun from Nonsolvent-Induced Phase-Separated Ternary Systems

Electrospinning of nonsolvent-induced phase-separated ternary (NIPST) systems has gained a lot of interest due to its potential to produce (nano)fibers, which are superficially and internally porous with nanoscale surface roughness. Membranes produced from such systems are expected to have a high specific surface area (SSA; e.g., more than 50 m² g^-1 ), an essential requirement for many of their applications. In spite of their advantages and potential, there are major issues regarding the electrospinning of NIPST systems that are not systematically addressed in the literature. In this paper, the most recent developments are reported and the potential and challenges associated with the electrospinning of NIPST systems are discussed. Furthermore, the essential steps to improve and optimize the electrospinning process of these systems are concisely discussed. By developing a modified time-dependent rheological model, a time range can be defined for NIPST systems as "electrospinnability window," in which fiber functionality and characteristics can be tailored through aging of the systems prior to electrospinning. Some potential post-treatment processes are also proposed based on the results of recent studies to stabilize as-electrospun membranes without damaging their highly porous fibers, which can guarantee their in-service mechanical and morphological stability.

Preferential adsorption of the additive is not a prerequisite for cononsolvency in water-rich mixtures

NMR studies reveal the distinct molecular interactions accounting for cononsolvency.