Biodegradable PHBH/PVA blend nanofibers: Fabrication, characterization, in vitro degradation, and in vitro biocompatibility

Fabrication of colon-targeted ethyl cellulose/gelatin hybrid nanofibers: Regulation of quercetin release and its anticancer activity

A colon-targeted delivery system that can efficiently deliver and release quercetin is essential to improve its bioavailability. We previously found that hydrophobic ethyl cellulose (EC) nanofibers could efficiently deliver quercetin to colon, but the release of quercetin was limited. To address this problem, hydrophilic gelatin (GN) was used as a regulator, and quercetin-loaded nanofibers with different mass ratios of EC to GN (3:1, 1:1, 1:2, 1:3) were fabricated by electrospinning. All nanofibers had a cylindrical morphology and high encapsulation efficiency (over 94 %), and there existed molecular interactions among quercetin, EC, and GN. The high GN content reduced the thermal stability of nanofibers but increased their surface wettability. Besides, these nanofibers had good stability in acidic and aqueous foods. Importantly, the release of quercetin in the simulated gastrointestinal fluid was <3 %. The addition of GN was beneficial to the release of quercetin in colon, and nanofibers with EC to GN being 1:3 had a more preferable release performance. The anticancer activity of nanofibers against HCT-116 cells was proved by inhibiting cell viability through the induction of apoptosis. Therefore, these nanofibers are potential carriers for efficient colon-targeted delivery of bioactive compounds in the food industry.

Perspectives of nanofibrous wound dressings based on glucans and galactans - A review

Wound healing is a complex and dynamic process that needs an appropriate environment to overcome infection and inflammation to progress well. Wounds lead to morbidity, mortality, and a significant economic burden, often due to the non-availability of suitable treatments. Hence, this field has lured the attention of researchers and pharmaceutical industries for decades. As a result, the global wound care market is expected to be 27.8 billion USD by 2026 from 19.3 billion USD in 2021, at a compound annual growth rate (CAGR) of 7.6 %. Wound dressings have emerged as an effective treatment to maintain moisture, protect from pathogens, and impede wound healing. However, synthetic polymer-based dressings fail to comprehensively address optimal and quick regeneration requirements. Natural polymers like glucan and galactan-based carbohydrate dressings have received much attention due to their inherent biocompatibility, biodegradability, inexpensiveness, and natural abundance. Also, nanofibrous mesh supports better proliferation and migration of fibroblasts because of their large surface area and similarity to the extracellular matrix (ECM). Thus, nanostructured dressings derived from glucans and galactans (i.e., chitosan, agar/agarose, pullulan, curdlan, carrageenan, etc.) can overcome the limitations associated with traditional wound dressings. However, they require further development pertaining to the wireless determination of wound bed status and its clinical assessment. The present review intends to provide insight into such carbohydrate-based nanofibrous dressings and their prospects, along with some clinical case studies.

Wound healing performance of PVA/PCL based electrospun nanofiber incorporated green synthetized CuNPs and Quercus infectoria extracts

In this study, copper nanoparticles (CuNPs) were synthetized through green chemistry approach using C. officinalis flowers extract. The biosynthetized nanoparticles were characterized by FESEM, XRD, DLS and FTIR analysis. Subsequently, PCL nanofiber was fabricated as first supportive layer by electrospinning method. Afterward, PVA/Quercus infectoria galls (QLG) extracts/biosynthetized CuNPs blending solution was electrospinned as second bioactive topical layer. The morphology, physicochemical properties and biological characteristics of the produced PCL, PCL/PVA, PCL/PVA/CuNPs, PCL/PVA/QLG and PCL/PVA/QLG/CuNPs were investigated. Eventually, in vivo wound healing effectiveness was examined. Histologic investigation was carried out for visualization of the healing wounds architecture in different treated groups. FESEM, XRD and DLS assays confirmed the successful synthesis of CuNPs in range of 40-70 nm and FTIR spectrum approve the presence of functional constituents of C. officinalis extract on synthesized CuNPs. The incorporation of CuNPs and QLG extract into PCL/PVA based nanofibers improved their biological capabilities and physicochemical properties. Furthermore, PCL/PVA/QLG/CuNPs illustrated significant wound healing potentials and excellent antibacterial function against at wounds infected with MRSA. Histological assay demonstrated complete wound healing and less inflammation on day 10th. These outcomes recommended the utilization of PCL/PVA/QLG/CuNPs as a novel promising wound dressings with considerable antibacterial features.

Optimization of Cellulose Nanofiber Loading and Processing Conditions during Melt Extrusion of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Bionanocomposites

This present study optimized the cellulose nanofiber (CNF) loading and melt processing conditions of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) P(HB-co-11% HHx) bionanocomposite fabrication in twin screw extruder by using the response surface methodology (RSM). A face-centered central composite design (CCD) was applied to statistically specify the important parameters, namely CNF loading (1-9 wt.%), rotational speed (20-60 rpm), and temperature (135-175 °C), on the mechanical properties of the P(HB-co-11% HHx) bionanocomposites. The developed model reveals that CNF loading and temperature were the dominating parameters that enhanced the mechanical properties of the P(HB-co-11% HHx)/CNF bionanocomposites. The optimal CNF loading, rotational speed, and temperature for P(HB-co-11% HHx) bionanocomposite fabrication were 1.5 wt.%, 20 rpm, and 160 °C, respectively. The predicted tensile strength, flexural strength, and flexural modulus for these optimum conditions were 22.96 MPa, 33.91 MPa, and 1.02 GPa, respectively, with maximum desirability of 0.929. P(HB-co-11% HHx)/CNF bionanocomposites exhibited improved tensile strength, flexural strength, and modulus by 17, 6, and 20%, respectively, as compared to the neat P(HB-co-11% HHx). While the crystallinity of P(HB-co-11% HHx)/CNF bionanocomposites increased by 17% under the optimal fabrication conditions, the thermal stability of the P(HB-co-11% HHx)/CNF bionanocomposites was not significantly different from neat P(HB-co-11% HHx).

Encapsulation of Monodisperse Microdroplets in Nanofibers through a Microfluidic-Electrospinning Hybrid Method

Fibers with droplets encapsulated in them could build bridges between a 0D dispersed structure and a 1D continuous wire and thus provide optimal solutions requiring high surface-to-volume ratio and strong mechanical properties. However, current methods are mostly focusing on the architectures with the size of droplets smaller than that of fibers; the relatively thick barrier of fibers usually limits the rate of diffusion from inner droplets to the outer environment. Here, we report a hybrid method combining microfluidics and electrospinning to fabricate nanofibers with microdroplets encapsulated in them. Monodisperse microdroplets with controllable sizes from 36 to 95 μm are generated through microfluidic flow-focusing and split into a string of smaller droplets from 1 to 3 μm, respectively, during the electrospinning stretching. The size of encapsulated droplets could be tuned by controlling the flow rate ratio during the microfluidic process, and the shape of that could be varied by changing the viscosity of encapsulated solution. This marriage of microfluidics and electrospinning could be applied to produce a nanofiber-based moisture barrier and drug carrier, also providing efficient tools to study the under-electric-field stretching and splitting of droplets trapped in the polymer network.

Agro waste as a potential carbon feedstock for poly-3-hydroxy alkanoates production: Commercialization potential and technical hurdles

The enormous production and widespread applications of non -biodegradable plastics lead to their accumulation and toxicity to animals and humans. The issue can be addressed by the development of eco-friendly strategies for the production of biopolymers by utilization of waste residues like agro residues. This will address two societal issues - waste management and the development of an eco-friendly biopolymer, poly-3-hydroxy alkanoates (PHAs). Strategies adopted for utilization of agro-residues, challenges and future perspectives are discussed in detail in this comprehensive review. The possibility of PHA properties improvements can be increased by preparation of blends.

Development and Characterization of Fully Renewable and Biodegradable Polyhydroxyalkanoate Blends with Improved Thermoformability

Poly(3-hydroxybutyrate-co-3-valerate) (PHBV), being one of the most studied and commercially available polyhydroxyalkanoates (PHAs), presents an intrinsic brittleness and narrow processing window that currently hinders its use in several plastic applications. The aim of this study was to develop a biodegradable PHA-based blend by combining PHBV with poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), another copolyester of the PHA family that shows a more ductile behavior. Blends of PHBV with 20% wt., 30% wt., and 40% wt. of PHBH were obtained by melt mixing, processed by cast extrusion in the form of films, and characterized in terms of their morphology, crystallization behavior, thermal stability, mechanical properties, and thermoformability. Full miscibility of both biopolymers was observed in the amorphous phase due to the presence of a single delta peak, ranging from 4.5 °C to 13.7 °C. Moreover, the incorporation of PHBH hindered the crystallization process of PHBV by decreasing the spherulite growth rate from 1.0 µm/min to 0.3 µm/min. However, for the entire composition range studied, the high brittleness of the resulting materials remained since the presence of PHBH did not prevent the PHBV crystalline phase from governing the mechanical behavior of the blend. Interestingly, the addition of PHBH greatly improved the thermoformability by widening the processing window of PHBV by 7 s, as a result of the increase in the melt strength of the blends even for the lowest PHBH content.

Nanofiber-Mâché Hollow Ball Mimicking the Three-Dimensional Structure of a Cyst

The occasional malignant transformation of intracranial epidermoid cysts into squamous cell carcinomas remains poorly understood; the development of an in vitro cyst model is urgently needed. For this purpose, we designed a hollow nanofiber sphere, the "nanofiber-mâché ball." This hollow structure was fabricated by electrospinning nanofiber onto alginate hydrogel beads followed by dissolving the beads. A ball with approximately 230 mm3 inner volume provided a fibrous geometry mimicking the topography of the extracellular matrix. Two ducts located on opposite sides provided a route to exchange nutrients and waste. This resulted in a concentration gradient that induced oriented migration, in which seeded cells adhered randomly to the inner surface, formed a highly oriented structure, and then secreted a dense web of collagen fibrils. Circumferentially aligned fibers on the internal interface between the duct and hollow ball inhibited cells from migrating out of the interior, similar to a fish bottle trap. This structure helped to form an adepithelial layer on the inner surface. The novel nanofiber-mâché technique, using a millimeter-sized hollow fibrous scaffold, is excellently suited to investigating cyst physiology.

Fabrication and Characterization of Collagen/PVA Dual-Layer Membranes for Periodontal Bone Regeneration

Guided tissue regeneration (GTR) is a promising treatment for periodontal tissue defects, which generally uses a membrane to build a mechanical barrier from the gingival epithelium and hold space for the periodontal regeneration especially the tooth-supporting bone. However, existing membranes possess insufficient mechanical properties and limited bioactivity for periodontal bone regenerate. Herein, fish collagen and polyvinyl alcohol (Col/PVA) dual-layer membrane were developed via a combined freezing/thawing and layer coating method. This dual-layer membrane had a clear but contact boundary line between collagen and PVA layers, which were both hydrophilic. The dual membrane had an elongation at break of 193 ± 27% and would undergo an in vitro degradation duration of more than 17 days. Further cell experiments showed that compared with the PVA layer, the collagen layer not only presented good cytocompatibility with rat bone marrow-derived mesenchymal stem cells (BMSCs), but also promoted the osteogenic genes (RUNX2, ALP, OCN, and COL1) and protein (ALP) expression of BMSCs. Hence, the currently developed dual-layer membranes could be used as a stable barrier with a stable degradation rate and selectively favor the bone tissue to repopulate the periodontal defect. The membranes could meet the challenges encountered by GTR for superior defect repair, demonstrating great potential in clinical applications.

Advantages of Additive Manufacturing for Biomedical Applications of Polyhydroxyalkanoates

In recent years, biopolymers have been attracting the attention of researchers and specialists from different fields, including biotechnology, material science, engineering, and medicine. The reason is the possibility of combining sustainability with scientific and technological progress. This is an extremely broad research topic, and a distinction has to be made among different classes and types of biopolymers. Polyhydroxyalkanoate (PHA) is a particular family of polyesters, synthetized by microorganisms under unbalanced growth conditions, making them both bio-based and biodegradable polymers with a thermoplastic behavior. Recently, PHAs were used more intensively in biomedical applications because of their tunable mechanical properties, cytocompatibility, adhesion for cells, and controllable biodegradability. Similarly, the 3D-printing technologies show increasing potential in this particular field of application, due to their advantages in tailor-made design, rapid prototyping, and manufacturing of complex structures. In this review, first, the synthesis and the production of PHAs are described, and different production techniques of medical implants are compared. Then, an overview is given on the most recent and relevant medical applications of PHA for drug delivery, vessel stenting, and tissue engineering. A special focus is reserved for the innovations brought by the introduction of additive manufacturing in this field, as compared to the traditional techniques. All of these advances are expected to have important scientific and commercial applications in the near future.

Fabrication of ciprofloxacin-loaded chitosan/polyethylene oxide/silica nanofibers for wound dressing application: In vitro and in vivo evaluations

Silica plays an effective role in collagen creation; hence, the degradation products of silica-based materials accelerate wound healing. In this regard, chitosan/polyethylene oxide/silica hybrid nanofibers were prepared by the combining the sol-gel method with electrospinning technique to accelerate the wound healing process. Ciprofloxacin, as an antibacterial drug, was then added to the electrospinning mixture. The nanofibers were characterized by SEM, EDX, X-ray mapping, TEM, TGA, FTIR, and XRD analysis. The degradation, swelling ratio, and release of ciprofloxacin were investigated in PBS. The prepared nanofiber could absorb water, maintain its morphological integrity during the degradation process, and gradually release ciprofloxacin. The nanofibers revealed an efficient antibacterial activity against Escherichia coli and Staphylococcus aureus. Cell viability assays showed that the nanofibers had no cytotoxicity against L929 mouse fibroblast and HFFF2 human foreskin fibroblast cell lines. The potential of the chitosan/polyethylene oxide/silica/ciprofloxacin nanofiber for healing full-thickness wound was assessed by applying the scaffold in the dorsal cutaneous wounds of the Balb/C mice. The white blood cell counts of the animals indicated the nanofiber-treated mice compared with the untreated ones had less infection and inflammation. According to the histopathologic data, the prepared nanofiber accelerated and enhanced tissue regeneration by increasing fibroblast cells and angiogenesis as well as decreasing the inflammation phase. The findings suggest that the prepared antibacterial scaffold with drug delivery properties could be an appropriate candidate for many medical and hygienic applications, especially as a bio-compatible and bio-degradable wound dressing.

Investigation and comparison of new galactosylation methods on PCL/chitosan scaffolds for enhanced liver tissue engineering

In liver tissue engineering, improving the ability of the scaffold to increase the tendency of cells to grow and proliferate is very important. In this study, new methods for modifying the surface of Polycaprolactone (PCL)/Chitosan (Cs) nanofiber for use in liver tissue engineering have been proposed. Galactosylation of chitosan was performed in three ways. According to the FE-SEM, FTIR, NMR and DSC analysis, presence of galactose in uniform nanofibers confirmed and led to a decrease in crystallinity. The hydrophobicity of the scaffolds by contact angle showed that the scaffold with galactosylated after electrospinning, had the highest contact angle of 82.22 ± 2° compared to raw scaffold with 98.52 ± 4°. According to the results of degradation in PBS, the highest rate of degradation was observed in scaffolds that were galactosylated after electrospinning. By culturing HepG2 cells on and based on the results of SEM and MTT analysis, found that the presence of galactose in the scaffolds significantly increased cell growth and proliferation without any toxicity. The immersion method shows a greater ability to improve the growth of liver cells. Also, using in-situ way due to the roughness created in this method may lead to better results especially for in-vivo tests.

The Growth of 3T3 Fibroblasts on PHB, PLA and PHB/PLA Blend Films at Different Stages of Their Biodegradation In Vitro

Over the past century there was a significant development and extensive application of biodegradable and biocompatible polymers for their biomedical applications. This research investigates the dynamic change in properties of biodegradable polymers: poly(3-hydroxybutyrate (PHB), poly-l-lactide (PLA), and their 50:50 blend (PHB/PLA)) during their hydrolytic non-enzymatic (in phosphate buffered saline (PBS), at pH = 7.4, 37 °C) and enzymatic degradation (in PBS supplemented with 0.25 mg/mL pancreatic lipase). 3T3 fibroblast proliferation on the polymer films experiencing different degradation durations was also studied. Enzymatic degradation significantly accelerated the degradation rate of polymers compared to non-enzymatic hydrolytic degradation, whereas the seeding of 3T3 cells on the polymer films accelerated only the PLA molecular weight loss. Surprisingly, the immiscible nature of PHB/PLA blend (showed by differential scanning calorimetry) led to a slower and more uniform enzymatic degradation in comparison with pure polymers, PHB and PLA, which displayed a two-stage degradation process. PHB/PLA blend also displayed relatively stable cell viability on films upon exposure to degradation of different durations, which was associated with the uneven distribution of cells on polymer films. Thus, the obtained data are of great benefit for designing biodegradable scaffolds based on polymer blends for tissue engineering.

Influence of Stabilizing and Encapsulating Polymers on Antioxidant Capacity, Stability, and Kinetic Release of Thyme Essential Oil Nanocapsules

The release kinetics, stability, and antioxidant capacity of thyme essential oil polymeric nanocapsules as a function of encapsulating (poly-ε-caprolactone and ethylcellulose) and stabilizing (polyvinyl alcohol and Pluronic^® F-127) polymers were established. Samples were evaluated in terms of particle size, zeta potential, release kinetics, calorimetry, infrared spectra, antioxidant capacity, and diffuse reflectance. The particle size obtained was below 500 nm in all cases, ensuring nanometric size. Zeta potential as a function of the stabilizing polymer. Encapsulation efficiency was higher in the samples that contained ethyl cellulose (around 70%), associated with its affinity for the molecules contained in the essential oil. Differential scanning calorimetry revealed a strong dependence on the encapsulating polymers as a function of the melting temperatures obtained. Infrared spectra confirmed that the polymeric nanocapsules had the typical bands of the aromatic groups of thyme essential oil. The antioxidant capacity evaluated is a function exclusively of the active content in the nucleolus of the nanocapsules. Nanoencapsulation was not a significant factor. Diffuse reflectance revealed high physical stability of the dispersions related directly to the particle size and zeta potential obtained (either by ionic or steric effect). These findings confirm favorable characteristics that allow proposing these systems for potential applications in food processing and preservation.

Facile in situ synthesis of silver nanoparticles on tannic acid/zein electrospun membranes and their antibacterial, catalytic and antioxidant activities

This study demonstrates the development of biocompatible Ag nanoparticles/Tannic acid/Zein electrospun membranes with synergistic antibacterial, catalytic and antioxidant activity. The optimal spinning concentration of zein was 32 wt%. The prepared zein electrospun membranes were immersed into tannic acid (TA) solution to investigate the effects of TA concentrations, pH, temperature and time on the loading amount of TA. Then, the TA/Zein electrospun membranes were immersed into a silver nitrate solution to reduce the AgNPs in situ. The morphology of the electrospun membranes was characterized by scanning electron microscopy (SEM). UV-visible spectrophotometer, Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to carry out the loading amount of TA and Ag nanoparticles (AgNPs). Finally, the antioxidant, antibacterial and catalytic activity of TA/Zein and AgNPs/TA/Zein electrospun membranes were studied. It was found that the AgNPs/TA/Zein electrospun membranes with different TA concentrations have certain antibacterial, antioxidation and catalytic ability, which may be of interest for the development of active packaging that could extend the shelf life of perishable foods.

Chemisorption and sustained release of cefotaxime between a layered double hydroxide and polyvinyl alcohol nanofibers for enhanced efficacy against second degree burn wound infection

Zn–Al layered double hydroxides (LDHs) were synthesized by a chemical method, while polyvinyl alcohol (PVA) nanofibers were fabricated by an electrospinning approach; we also synthesized Zn–Al LDH/cefotaxime (cefotax), Zn–Al LDH@PVA, and Zn–Al LDH/cefotax@PVA (LCP). Characterizations were performed by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller analysis, thermogravimetric-differential thermal analysis techniques, dynamic light scattering, X ray-florescence, and carbon, hydrogen, and nitrogen (CHN) analyses. The adsorption isotherm of cefotax and its entrapment percentage, release, and kinetics were also investigated. The results confirmed the elemental constituents of the mentioned formulas, which exhibited different degrees of crystallinity and different morphologies. Besides, these formulas were tested in vitro as antimicrobial agents and applied in vivo against second-degree wound burns induced in rats' skin. The adsorption of cefotax occurred chemically, and the experimental data were fitted with different isotherm models, where the Freundlich and Toth models gave the best fits. The entrapment percentage in LDH/cefotax was 77.41% and in LDH/cefotax@PVA, it was 67.83%. The sustained release of cefotax from LDH and LCP was attainable; the release percentages were 89.31% and 81.55% in up to 12 h, respectively. The release kinetics of cefotax from LDH fitted well with first-order kinetics, while that for LCP was parabolic. The formulas showed uneven antimicrobial effects against Gram-positive and Gram-negative bacteria; the best effect was exhibited by Zn–Al LDH/cefotax@PVA due to its sustained release. Finally, investigating the possibility of using these formulas in the clinical setting should be considered.

This study succeeded to formulate, characterize, and investigate cefotax release and kinetics, and to compare cetofax with other known antibacterial agents.

Seawater-Degradable Polymers-Fighting the Marine Plastic Pollution

Polymers shape human life but they also have been identified as pollutants in the oceans due to their long lifetime and low degradability. Recently, various researchers have studied the impact of (micro)plastics on marine life, biodiversity, and potential toxicity. Even if the consequences are still heavily discussed, prevention of unnecessary waste is desired. Especially, newly designed polymers that degrade in seawater are discussed as potential alternatives to commodity polymers in certain applications. Biodegradable polymers that degrade in vivo (used for biomedical applications) or during composting often exhibit too slow degradation rates in seawater. To date, no comprehensive summary for the degradation performance of polymers in seawater has been reported, nor are the studies for seawater-degradation following uniform standards. This review summarizes concepts, mechanisms, and other factors affecting the degradation process in seawater of several biodegradable polymers or polymer blends. As most of such materials cannot degrade or degrade too slowly, strategies and innovative routes for the preparation of seawater-degradable polymers with rapid degradation in natural environments are reviewed. It is believed that this selection will help to further understand and drive the development of seawater-degradable polymers.

Oxidation of Flame Retardant Tetrabromobisphenol A by a Biocatalytic Nanofiber of Chloroperoxidase

Background: Tetrabromobisphenol (TBBPA), a flame retardant compound, is considered a ubiquitous pollutant, with potential impact on the environment and human health. Several technologies have been applied to accelerate its degradation and minimize environmental impacts. Due to its aromaticity character, peroxidase enzymes may be employed to carry out its transformation in mild conditions. Therefore, the purpose of this work was to determine the capacity of the enzyme chloroperoxidase (CPO) to oxidize TBBPA in several water samples. Methods: The oxidation capacity of CPO was evaluated in catalytic conditions using water samples from surface and groundwater, as well as effluents from wastewater treatment plants. The biocatalytic performance of CPO was improved due to its immobilization on nanofibers composed of polyvinyl alcohol and chitosan (PVA/chitosan). Results: Free and immobilized CPO were able to transform more than 80% in short reaction times (60 min); producing more biodegradable and less toxic products. Particularly, the immobilized enzyme was catalytically active in a wider range of pH than the free enzyme with the possibility of reusing it up to five times. Conclusions: The biocatalytic oxidation of TBBPA under environmental conditions is highly efficient, even in complex media such as treated effluents of wastewater treatment plants.

Natural Antibacterial Reagents (Centella, Propolis, and Hinokitiol) Loaded into Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] Composite Nanofibers for Biomedical Applications

Centella asiatica, propolis, and hinokitiol, as natural antibacterial reagents, were integrated into the poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (PHBH) polymer to produce antibacterial wound dressings, using electrospinning process. The results showed that the fiber diameters and surface morphology of PHBH composite nanofibers were influenced by the addition of ethanol–centella (EC), methanol–centella (MC), ethanol–propolis (EP), and ethanol–hinokitiol (EH) at various ratios compared to pristine PHBH nanofibers. From FT-IR, the nanofibrous samples with higher contents of natural antibacterial substances showed the peaks of carboxylic acid, aromatic ring, and tropolone carbon ring from centella, propolis, and hinokitiol, respectively. Furthermore, the tensile strength of neat PHBH nanofibers was increased from 8.00 ± 0.71 MPa up to 16.35 ± 1.78 MPa by loading of propolis (EP) 7% into PHBH. X-ray analysis explained that the loading of propolis (EP) was also able to increase the crystallinity in PHBH composite nanofibers from 47.0% to 54.5%. The antibacterial results demonstrated that PHBH composite nanofibers containing natural antibacterial products were potent inhibitors against the growth of Escherichia coli and Staphylococcus aureus, amongst them hinokitiol and propolis proved to be the most effective. Additionally, the release studies displayed that centella and hinokitiol had faster release from PHBH composite nanofibers in comparison to propolis.

Formulation and optimization of drug-loaded mesoporous silica nanoparticle-based tablets to improve the dissolution rate of the poorly water-soluble drug silymarin

Porous carriers have been put forward as a promising alternative for stabilizing the amorphous state of loaded drugs, and thus significantly improving the dissolution rate of poorly soluble compounds. The purpose of this study was to enhance the saturation solubility, dissolution rate and drug loading of the poorly water-soluble drug silymarin via incorporation into mesoporous silica nanospheres within a lyophilized tablet to obtain a unique formulation. 3² full factorial design was applied to study the effect of both independent variables, polyvinyl alcohol (PVA) as stabilizer and binder and sucrose as cryoprotectant and disintegrant; and on the dependent variables that included the mean particle size (Y₁), disintegration time (Y₂), tablet strength (Y₃) and % of drug release after 2 min, R_2min,Y₄. The drug-loaded mesoporous silica nanospheres and the optimized formula was evaluated by different characterization methods: scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, X-ray diffractometry and Fourier transform infrared spectroscopy; as well as drug content, saturation solubility and moisture content. The evaluation demonstrated that the loaded mesoporous silica nanospheres and the optimized formula are in amorphous state without any chemical interaction with the silica matrix or the stabilizer. Moreover, the drug was stably maintained in nanosize range with narrow particle size distribution. Furthermore, the optimized lyophilized tablets had highly porous structure, low friability (less than 1%), fast disintegration (less than 30 s), high tablet strength, low moisture content (less than 1%), remarkably increased dissolution rate and noticeable improvement in saturation solubility.

Electrospun Polyvinyl Alcohol/d-Limonene Fibers Prepared by Ultrasonic Processing for Antibacterial Active Packaging Material

Novel fibers containing different ratios of PVA and d-limonene were fabricated using electrospinning for antibacterial active packaging applications. The PVA/d-limonene fibers were thoroughly characterized using a scanning electron microscope, fourier-transform infrared spectrometry, thermal gravimetry, differential scanning calorimetry, tensile tests, and oxygen permeability tests. The results of these analyses showed that the highest tensile strength and elongation at break values of 3.87 ± 0.25 MPa and 55.62 ± 2.93%, respectively, were achieved for a PVA/d-limonene ratio of 7:3 (v/v) and an ultrasonication time of 15 min during processing. This material also showed the lowest oxygen permeation and the best degradability and bacteriostatic properties of all samples.