Evaluation of chitosan/PVA blended hydrogel membranes

Application of biodegradable colorimetric films based on purple tomatoes anthocyanins loaded chitosan and polyvinyl alcohol in pork meat

A series of biodegradable colorimetric films were prepared by using chitosan and polyvinyl alcohol as matrix, in which, the weight ratio of chitosan: Polyvinyl alcohol was 100: 0, 80: 20, 50: 50, 20: 80, or 0: 100, with addition of 10% (w/w, relative to chitosan) anthocyanins extracted from purple tomatoes (purple tomatoes anthocyanin) as pigment. The aim of this study was to observe the effect of weight ratio (chitosan: Polyvinyl alcohol) on the mechanical properties, contact angle, swelling rate, pH sensitivity, antioxidant properties of chitosan-polyvinyl alcohol/purple tomatoes anthocyanins films, and the antibacterial activity of films produced for pork packaging. In addition, the films as a smart colorimetric indicator for monitoring the freshness of pork was investigated. The results showed that as the ratio of chitosan to polyvinyl alcohol decreases, the elongation at break, hydrophilicity, and swelling rate of the films increased especially from 16.5% to 174.2% for elongation at break and 93.0° to 53.8° for water contact angle, however, the tensile strength decreased from 67.3 to 24.7 MPa. With decreasing of chitosan: Polyvinyl alcohol, the antibacterial activity on pork was decreased, and the antioxidant properties of films increased first then decreased. Fourier transform infrared spectroscopy indicated there were interactions among chitosan, polyvinyl alcohol, and purple tomatoes anthocyanins. The color response of films was depended on pH, as well as the immersion time. The longer immersion resulted in a more pronounced color change. The color changed from purplish red (pH 2-4) to green (pH 5-10) to yellow (pH 10-12). In monitoring the freshness of pork, the film showed a nice visual color change, indicating a potential application in smart packaging. These bio-based materials may be useful alternatives to synthetic plastics for food applications such as active and smart packaging, thereby improving the environmental friendliness and sustainability of the food supply.

In Vitro and Randomized Controlled Clinical Study of Natural Constituents' Anti-HPV Potential for Treatment of Plantar Warts Supported with In Silico Studies and Network Analysis

The aim of this study is to evaluate the anti-HPV potential of a Moringa olifera Lam seed, Nigella sativa L. seed, and Musa Acuminata peel herbal mixture in the form of polymer film-forming systems. A clinical trial conducted in outpatient clinics showed that the most significant outcome was wart size and quantity. Compared to the placebo group, the intervention group's size and number of warts were considerably better according to the results. Chemical profiling assisted by LC-HRMS led to the dereplication of 49 metabolites. Furthermore, network pharmacology was established for the mixture of three plants; each plant was studied separately to find out the annotated target genes, and then, we combined all annotated genes of all plants and filtered the genes to specify the genes related to human papilloma virus. In a backward step, the 24 configured genes related to HPV were used to specify only 30 compounds involved in HPV infection based on target genes. CA2 and EGFR were the top identified genes with 16 and 12 edges followed by PTGS2, CA9, and MMP9 genes with 11 edges each. A molecular docking study for the top active identified compounds of each species was conducted in the top target HPV genes, CA2 and EGFR, to investigate the mode of interaction between these compounds and the targets' active sites.

Polyoxometalate nanocluster-infused triple IPN hydrogels for excellent microplastic removal from contaminated water: detection, photodegradation, and upcycling

Microplastic (MP) pollution pervades global ecosystems, originating from improper plastic disposal and fragmentation due to factors like hydrolysis and biodegradation. These minute particles, less than 5 mm in size, have become omnipresent, impacting terrestrial, freshwater, and marine environments worldwide. Their ubiquity poses severe threats to marine life by causing physical harm and potentially transferring toxins through the food chain. Addressing this environmental crisis necessitates a sustainable strategy. Our proposed solution involves a highly efficient copper substitute polyoxometalate (Cu-POM) nanocluster infused triple interpenetrating polymer network (IPN) hydrogel, comprising chitosan (CS), polyvinyl alcohol (PVA), and polyaniline (PANI) (referred to as pGel@IPN) for mitigating MP contamination from water. This 3D IPN architecture, incorporating nanoclusters, also enhances the hydrogel's photodegradation capabilities. Our scalable approach offers a sustainable strategy to combat MPs in water bodies, as demostrated by the adsorption behaviors on the hydrogel matrix under varying conditions, simulating real-world scenarios. Evaluations of physicochemical properties, mechanical strength, and thermal behavior underscore the hydrogel's robustness and stability. Detecting minute MP particles remains challenging, prompting us to label MPs with Nile red for fluorescence microscopic analysis of their concentration and adsorption on the hydrogel. The catalytic properties of POM within the hydrogel facilitate UV-induced MP degradation, highlighting a sustainable solution. Our detailed kinetics and isotherm studies revealed pseudo-first-order and Langmuir models as fitting descriptors for MP adsorption, exhibiting a high maximum adsorption capacity (Qm). Notably, pGel@IPN achieved ∼95% and ∼93% removal efficiencies for polyvinyl chloride (PVC) and polypropylene (PP) MPs at pH ∼ 6.5, respectively, also demonstrating reusability for up to 5 cycles. Post-end-of-life, the spent adsorbent was efficiently upcycled into carbon nanomaterials, effectively removing the heavy metal Cr(VI), exemplifying circular economy principles. Our prepared hydrogel emerges as a potent solution for MP removal from water, promising effective mitigation of the emerging pollutants of MPs while ensuring sustainable environmental practices.

Sonochemical synthesis of lignin nanoparticles and their applications in poly (vinyl) alcohol composites

Lignin is a common and abundant byproduct of the pulp and paper industry and is generally burned to produce steam. Opportunities exist to acquire greater value from lignin by leveraging the properties of this highly conjugated biomacromolecule for applications in UV absorption and polymer reinforcement. These applications can be commercialized by producing value-added lignin nanoparticles (LNPs) using a scalable sonochemical process. In the present research, monodisperse LNPs have been synthesized by subjecting aqueous dispersions of alkali lignin to acoustic irradiation. The resulting particle size distribution and colloidal stability, as determined by dynamic light scattering, transmission electron microscopy and zeta potential analysis, of LNPs can be adjusted by varying the solution pH and ultrasonication energy. As-synthesized LNPs with a mean diameter of 204 nm were incorporated into poly (vinyl) alcohol (PVA) to prepare thin and flexible nanocomposite films using a simple solvent casting method. The addition of 2.5 wt% LNP increased the material's Sun Protection Factor up to 26 compared to 0 for neat PVA, while maintaining light transmission above 75 % in the visible spectra. In addition, the tensile strength and elastic modulus of the PVA nanocomposites improved by 47 % and 36 %, respectively. The presence of LNP also enhanced the thermal stability of the materials. Significantly, the proposed sonochemical process may be generally applicable to the synthesis of a range of naturally-derived LNPs for a variety of value-added applications.

Experimental investigations on PVA/chitosan and PVA/chitin films for active food packaging using Oxytenanthera abyssinica lignin nanoparticles and its UV-shielding, antimicrobial, and antiradical effects

This study investigated the effect of adding lignin nanoparticles (LNPs) derived from Oxytenanthera abyssinica via alkali-acid nanoprecipitation method to polyvinyl alcohol/chitosan (PVA/CI) and polyvinyl alcohol/chitin (PVA/CH) films for the active food packaging applications. Adding LNPs at concentrations of 1 % and 3 % improved the films' thermal stability and mechanical properties. The lowest water solubility and moisture content were observed in PVA/CI/LNPs films. LNPs exhibited effective 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities, with the highest values observed in PVA/CH/LNPS and PVA/CI/LNPS films with values of 87.47 and 88.74 % respectively. The addition of LNPs also improved the UV-blocking abilities of the films. PVA/CH/LNP3 and PVA/CI/LNP3 have the smallest percentage transmission values of 3.34 % and 0.86 % in the UV range. The overall migration of dietary stimulants was lower in PVA/CI/LNPS and PVA/CH/LNPS films compared to PVA film. Antibacterial tests demonstrated the inhibitory capacity of the synthesized biofilms against both gram-positive and negative bacterial species, with the highest inhibitory value of 26 mm. The study suggests that PVA/CH/LNPS and PVA/CI/LNPS films have potential applications as active food packaging materials and can be explored in other potential applications such as drug delivery, tissue engineering, wound healing, and slow-release urea fertilizer development.

Investigation on Akis granulifera (Coleoptera, Sahlberg, 1823) as a potential source of chitin and chitosan: Extraction, characterization and hydrogel formation

The majority of studies have focused on the industrial exploitation of marine fisheries waste through the production of natural bioactive bioploymeres such as chitin and chitosan. However, in recent years, beetles are increasingly attracting the interest of scientists as a source of chitin and chitosan for the preparation of hydrogels for sustainable engineering development. In the present work, we focus on the study for the first time a new Moroccan species of beetle (Akis granulifera Sahlberg, 1823), for the extraction of chitin and the elaboration of chitosan. A chemical extraction process was used. Then, physicochemical characterizations by FT-IR, SEM, XRD, 1H NMR, TGA/DSC, Potentiometry, Viscosimetry, and elemental analysis were performed. In addition, to evaluate its physicochemical quality, the elaborated chitosan is combined with alginate to form a hydrogel. This hydrogel was effectively characterized by SEM, DRX and FTIR to show the potential of chitosan from Akis granulifera in biomaterial applications.

Influence of Thermal Treatment and Acetic Acid Concentration on the Electroactive Properties of Chitosan/PVA-Based Micro- and Nanofibers

This study presents, for the first time, a comprehensive investigation of the influence of pre- and post-fabrication parameters for the electroactive properties of electrospun chitosan/PVA-based micro- and nanofibers. Chitosan/PVA fibers were fabricated using electrospinning, characterized, and tested as electroactive materials. Solutions with different acetic acid contents (50, 60, 70, and 80 v/v%) were used, and the rheological properties of the solutions were analyzed. Characterization techniques, such as rheology, conductivity, optical microscopy, a thermogravimetric analysis, differential scanning calorimetry, a tensile test, and FT-IR spectroscopy, were utilized. Fiber mats from the various solutions were thermally treated, and their electroactive behavior was examined under a constant electric potential (10 V) at different pHs (2-13). The results showed that fibers electrospun from 80% acetic acid had a lower electroactive response and dissolved quickly. However, thermal treatment improved the stability and electroactive response of all fiber samples, particularly the ones spun with 80% acetic acid, which exhibited a significant increase in speed displacement from 0 cm-1 (non-thermally treated) to 1.372 cm-1 (thermally treated) at a pH of 3. This study sheds light on the influence of pre- and post-fabrication parameters on the electroactive properties of chitosan/PVA fibers, offering valuable insights for the development of electroactive materials in various applications.

Rational design of antimicrobial peptide conjugated graphene-silver nanoparticle loaded chitosan wound dressing

Wound dressing with poor antibacterial properties, the tendency to adhere to the wound site, poor mechanical strength, and lack of porosity and flexibility are the major cause of blood loss, delayed wound repair, and sometimes causes death during the trauma or injury. In such cases, hydrogel-based antibacterial wound dressing would be a boon to the existing dressing as the moist environment will maintain the cooling temperate and proper exchange of atmosphere around the wound. In the present study, the multifunctional graphene with silver and ε-Poly-l-lysine reinforced into the chitosan matrix (CGAPL) was prepared as a nanobiocomposite wound dressing. The contact angle measurement depicted the hydrophilic property of CGAPL nanobiocomposite dressing (water contact angle 42°), while the mechanical property was 78.9 MPa. The antibacterial and cell infiltration study showed the antimicrobial property of CGAPL nanobiocomposite wound dressing. It also demonstrated no cytotoxicity to the L929 fibroblast cells. Chorioallantoic Membrane (CAM) assay showed the pro-angiogenic potential of CGAPL nanobiocomposite wound dressing. In-vitro scratch wound assay confirmed the migration of cells and increased cell adhesion and proliferation within 18 h of culture on the surface of CGAPL nanobiocomposite dressing. Later, the in-vivo study in the Wistar rat model showed that CGAPL nanobiocomposite dressing significantly enhanced the wound healing process as compared to the commercially available wound dressing Tegaderm (p-value <0.01) and Fibroheal@Ag (p-value <0.005) and obtained complete wound closure in 14 days. Histology study further confirmed the complete healing process, re-epithelization, and thick epidermis tissue formation. The proposed CGAPL nanobiocomposite wound dressing thus offers a novel wound dressing material with an efficient and faster wound healing property.

Targeted release of soybean peptide from CMC/PVA hydrogels in simulated intestinal fluid and their pharmacokinetics

Carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) hydrogels loaded with soybean peptide (SPE) were fabricated via a freeze-thaw method. These hydrogels conquer barriers in simulated gastric fluid (SGF), and then release SPE in simulated intestinal fluid (SIF). The results of in vitro SPE release from these hydrogels showed that in SGF only a little of the SPE released, but in SIF the SPE was completely released. The released SPE had scavenging rates for DPPH and ABTS free radicals of 41.68 and 31.43 %. The pharmacokinetic model of SPE release from the hydrogels in SIF was studied. When the hydrogels are moved from SGF to SIF, the sorption of the shrinkage hydrogel network is entirely controlled by stress-induced relaxations. There are swollen and shrunken regions during SPE release. For SPE release into the SIF, SPE has to be freed from the weak bonds in the swollen regions by changes in the conformation of CMC and PVA. The release rate of SPE was found to be governed by the diffusion and swelling rate of the shrinkage hydrogel network. The Korsmeyer-Peppas equation diffusion exponents (n) for SPE release from the hydrogels are >2.063, indicating a super case II transport. These data demonstrate CMC/PVA hydrogels have potential applications in oral peptide delivery.

PEG 400:Trehalose Coating Enhances Curcumin-Loaded PLGA Nanoparticle Internalization in Neuronal Cells

This work proposes a combination of polyethylene glycol 400 (PEG) and trehalose as a surface modification approach to enhance PLGA-based nanoparticles as a drug carrier for neurons. PEG improves nanoparticles' hydrophilicity, and trehalose enhances the nanoparticle's cellular internalization by inducing a more auspicious microenvironment based on inhibiting cell surface receptor denaturation. To optimize the nanoprecipitation process, a central composite design was performed; nanoparticles were adsorbed with PEG and trehalose. PLGA nanoparticles with diameters smaller than 200 nm were produced, and the coating process did not considerably increase their size. Nanoparticles entrapped curcumin, and their release profile was determined. The nanoparticles presented a curcumin entrapment efficiency of over 40%, and coated nanoparticles reached 60% of curcumin release in two weeks. MTT tests and curcumin fluorescence, with confocal imaging, were used to assess nanoparticle cytotoxicity and cell internalization in SH-SY5Y cells. Free curcumin 80 µM depleted the cell survival to 13% at 72 h. Contrariwise, PEG:Trehalose-coated curcumin-loaded and non-loaded nanoparticles preserved cell survival at 76% and 79% under the same conditions, respectively. Cells incubated with 100 µM curcumin or curcumin nanoparticles for 1 h exhibited 13.4% and 14.84% of curcumin's fluorescence, respectively. Moreover, cells exposed to 100 µM curcumin in PEG:Trehalose-coated nanoparticles for 1 h presented 28% fluorescence. In conclusion, PEG:Trehalose-adsorbed nanoparticles smaller than 200 nm exhibited suitable neural cytotoxicity and increased cell internalization proficiency.

Effect of Chitosan as Active Bio-colloidal Constituent on the Diffusion of Dyes in Agarose Hydrogel

Agarose hydrogel was enriched by chitosan as an active substance for the interactions with dyes. Direct blue 1, Sirius red F3B, and Reactive blue 49 were chosen as representative dyes for the study of the effect of their interaction with chitosan on their diffusion in hydrogel. Effective diffusion coefficients were determined and compared with the value obtained for pure agarose hydrogel. Simultaneously, sorption experiments were realized. The sorption ability of enriched hydrogel was several times higher in comparison with pure agarose hydrogel. Determined diffusion coefficients decreased with the addition of chitosan. Their values included the effects of hydrogel pore structure and interactions between chitosan and dyes. Diffusion experiments were realized at pH 3, 7, and 11. The effect of pH on the diffusivity of dyes in pure agarose hydrogel was negligible. Effective diffusion coefficients obtained for hydrogels enriched by chitosan increased gradually with increasing pH value. Electrostatic interactions between amino group of chitosan and sulfonic group of dyes resulted in the formation of zones with a sharp boundary between coloured and transparent hydrogel (mainly at lower pH values). A concentration jump was observed at a given distance from the interface between hydrogel and the donor dye solution.

Chitosan/PVA Nanofibers as Potential Material for the Development of Soft Actuators

Chitosan/PVA nanofibrous electroresponsive soft actuators were successfully obtained using an electrospinning process, which showed fast speed displacement under an acidic environment. Chitosan/PVA nanofibers were prepared and characterized, and their electroactive response was tested. Chitosan/PVA nanofibers were electrospun from a chitosan/PVA solution at different chitosan contents (2.5, 3, 3.5, and 4 wt.%). Nanofibers samples were characterized using Fourier transform infrared analyses, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), optical microscopy, and tensile test. The electroactive behavior of the nanofiber hydrogels was tested under different HCl pH (2-6) under a constant voltage (10 V). The electroactive response test showed a dependence between the nanofiber's chitosan content and pH with the bending speed displacement, reaching a maximum speed displacement of 1.86 mm^-1 in a pH 3 sample with a chitosan content of 4 wt.%. The results of the electroactive response were further supported by the determination of the proportion of free amine groups, though deconvoluting the FTIR spectra in the range of 3000-3700 cm^-1. Deconvolution results showed that the proportion of free amine increased as the chitosan content was higher, being 3.6% and 4.59% for nanofibers with chitosan content of 2.5 and 4 wt.%, respectively.

POTENTIAL BENEFITS OF USING CHITOSAN AND SILK FIBROIN TOPICAL HYDROGEL FOR MANAGING WOUND HEALING AND COAGULATION

Background & Objectives

The intricate process of wound healing involves replacing the cellular or tissue structure that has been destroyed. In recent years various wound dressings were launched but reported several limitations. The topical gel preparations are intended for certain skin wound conditions for local action. Chitosan-based hemostatic materials are the most effective in halting acute hemorrhage, and naturally occurring silk fibroin is widely utilized for tissue regeneration. So, this study was conducted to evaluate the potential of chitosan hydrogel(CHI-HYD) and chitosan silk fibroin hydrogel (CHI-SF-HYD) on blood clotting and wound healing.

Methods

Hydrogel was prepared using various concentrations of silk fibroin with guar gum as a gelling agent. The optimized formulations were evaluated for visual appearance, Fourier transforms infrared spectroscopy (FT-IR), pH, spreadability, viscosity, antimicrobial activity, HR-TEM analysis, ex vivo skin permeation, skin irritation, stability studies, and in vivo studies by using adult male Wistar albino rats.

Results

Based on the outcome of FT-IR, no chemical interaction between the components was noticed. The developed hydrogels exhibited a viscosity of 79.2 ± 4.2 Pa.s (CHI-HYD), 79.8 ± 3.8 Pa.s (CHI-SF-HYD), and pH of 5.87 ± 0.2 (CHI-HYD), 5.96 ± 0.1 (CHI-SF-HYD). The prepared hydrogels were sterile and non-irritant to the skin. The in vivo study outcomes show that the CHI-SF-HYD treated group has significantly shortened the span of tissue reformation than other groups. This demonstrated that the CHI-SF-HYD could consequently accelerate the regeneration of the damaged area.

Interpretation & Conclusion

Overall, the positive outcomes revealed improved blood coagulation and re-epithelialization. This indicates that the CHI-SF-HYD could be used to develop novel wound-healing devices.

A nanofiber-hydrogel composite from green synthesized AgNPs embedded to PEBAX/PVA hydrogel and PA/Pistacia atlantica gum nanofiber for wound dressing

A polyamide/Pistacia atlantica (P.a) gum nanofiber, fabricated by electrospinning method, was coated on a layer of PEBAX/PVA hydrogel embedded with green synthesized Ag nanoparticles (AgNPs) and the prepared nanofiber-hydrogel composite was assessed for wound dressing application. The AgNPs were characterized using ultraviolet-visible (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Zeta potential analysis. The PEBAX/PVA/Ag hydrogel, prepared using solution casting method, displayed strong mechanical properties as Young's modulus and the elongation at break for the hydrogel containing AgNPs increased by 12 % and 96 %, respectively. The PEBAX/PVA/Ag hydrogel showed a high antimicrobial activity towards the E. coli (22.8 mm) with no cytotoxicity. The effect of adding the P.a gum on the properties of polyamide nanofiber was investigated using FTIR, SEM, and tensile tests. Samples were assessed by swelling, degradation, and water vapor transfer measurements. Very fine and continuous fibers with average diameters of ≤200 nm were observed by SEM analysis due to the addition of the P.a gum. The result of tensile test indicated that the addition of P.a gum improves the mechanical properties of nanofibers. The physical properties and biocompatibility of the two layers were shown to be complementary when combined.

Green multifunctional PVA composite hydrogel-membrane for the efficient purification of emulsified oil wastewater containing Pb2+ ions

To date, most existing engineering materials have difficulty simultaneously separating oil/water and removing heavy metals from complex oily wastewater. In response to this challenge, a novel multifunctional composite hydrogel membrane (named PVA-CS-LDHs) was fabricated by incorporating chitosan (CS) and nanohydrotalcite (LDHs) into a polyvinyl alcohol (PVA) hydrogel. This material was developed using an easy yet versatile strategy of freezing and salting-out, which can enable the formation of a PVA-CS-LDH hydrogel membrane in one step and endow the PVA-CS-LDHs with high strength, excellent stretchability, favourable shape recoverability, and an ideal 3D microstructure. The PVA-CS-LDH membrane can purify emulsified oil and metal ions simultaneously with a separation efficiency of 99.89 % for emulsified oil and a removal efficiency of 97.44 % for Pb2+ ions. Additionally, the high-efficiency, multifunctional, high-antifouling and eco-friendly properties of the PVA-CS-LDH membrane make it a promising hydrogel material for both emulsified oil separation and heavy metal ion removal. Thus, this material provides critical application potential that can address scientific and technological challenges in complex oily wastewater purification.

Centrifugally Spun PVA/PVP Based B, N, F Doped Carbon Nanofiber Electrodes for Sodium Ion Batteries

Owing to their high electrical conductivity, high surface area, low density, high thermal stability, and chemical stability, carbon nanofibers have been used in many fields, including energy storage, electromagnetic shielding, filtering, composites, sensors, and tissue engineering. Considering the environmental impact of petroleum-based polymers, it is vital to fabricate carbon nanofibers from environmentally-friendly materials using fast and safe techniques. PVA/PVP nanofibers were fabricated via centrifugal spinning and the effects of variations in the PVP content on the morphology and thermal properties of PVA/PVP-blend nanofibers were studied using SEM and DSC analyses. Moreover, the effects of carbonization conditions, including stabilization time, stabilization temperature, carbonization time, and carbonization temperature on the morphology and carbon yield, were investigated. Centrifugally spun PVA/PVP-based carbon nanofiber electrodes with an average fiber diameter around 300 nm are reported here for the first time. Furthermore, centrifugally spun PVA/PVP-based B, N, F-doped carbon nanofibers were fabricated by combining centrifugal spinning and heat treatment. Through B, N, F doping, CNFs demonstrated a high reversible capacity of more than 150 mAh/g in 200 cycles with stable cycling performance.

Multifunctional dual cross-linked poly (vinyl alcohol)/methacrylate hyaluronic acid/chitooligosaccharide-sinapic acid wound dressing hydrogel

Wound dressing hydrogel with multifunctional properties, including antioxidant and antimicrobial properties and appropriate mechanical, biological, and physical properties is of great interest in wound healing application and it is still a challenge. In the present study, chitooligosaccharides (COS)/ sinapic acid (SA) conjugate (COS-SA) was synthesized using H₂O₂-induced grafting polymerization, and photo cross-linkable hyaluronic acid was synthesized using methacrilation (HAMA). The synthesis of COS-SA and HAMA was confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, and polyphenol assay. Subsequently, we developed duel cross-linked polyvinyl alcohol (PVA)/HAMA composite hydrogel encapsulated with COS-SA as an antioxidant and antimicrobial dressing for full-thickness wound healing application. The chemical, physical, mechanical, antioxidant, antimicrobial, in vitro biocompatibility, and in vivo wound healing properties of hydrogels were subsequently investigated. The results showed that the fabricated composite hydrogel had a uniform porous architecture, excellent fluid absorbability, and appropriate mechanical stability. The introduction of COSs-SA conjugate remarkably enhanced the in vitro biocompatibility, antioxidant, and antimicrobial properties of the hydrogel, leading to the significant promotion of in vivo full-thickness wound closure, re-epithelization, granulation tissue formation, and collagen deposition indicating that COSs-SA incorporated PVA/HAMA hydrogel wound dressing has significant potential for chronic wound healing application.

Preparation and characterization of N-doped ZnO and N-doped TiO2 beads for photocatalytic degradation of phenol and ammonia

N-doped ZnO beads (NZB) and N-doped TiO₂ beads (NTB) were synthesized via a modified sol-gel technique utilizing chitosan (CS)/polyvinyl alcohol (PVA) hydrogel beads as basic support for photocatalyst. Urea was used as a source of nitrogen in the preparation of N-doped ZnO beads, while ammonium acetate, CH₃COONH₄, was used as a nitrogen source in the production of N-doped TiO₂ beads. The characteristics of synthesized beads were identified by scanning electron microscope (SEM), X-ray photoelectron spectroscopy analysis (XPS), X-ray diffraction (XRD), N₂ adsorption-desorption isotherms, BET surface area, Fourier transform infrared (FT-IR) measurements, and diffuse reflectance spectroscopy (DRS) studies. The use of the nitrogen doping method for photocatalyst was performed to adjust the bandgap and electrical properties of ZnO and TiO₂ by establishing acceptor defects. NZB and NTB with the intrinsic donor defect of oxygen vacancy and the nitrogen-to-oxygen acceptor defect could be activated by a less-energy UV consumption for efficient pollutant degradation. The results indicated that the as-synthesized NZB achieved much higher degradation activity than NTB, commercial ZnO, and TiO₂ in the decomposition of a binary mixture composed of ammonia and phenol under UV light irradiation.

Green and Efficient Preparation of Tailed Lignin Nanoparticles and UV Shielding Composite Films

Lignin nanoparticles (LNP) with various morphologies could be prepared with solvent-antisolvent methods. However, the employed toxic chemicals limited its large-scale application. In this study, an extremely green method using only ethanol and water as solvent and antisolvent was reported. Besides, with the syringaldehyde (SA) addition and its anchoring action on the lignin particles, a forming process of the tailed structure was observed and resulted. Moreover, the improved electronegativity originating from the phenolic hydroxyl groups enhanced the size distribution uniformity, and the new absorption peaks at 1190 cm-1 demonstrated the involvement of SA in the LNP formation. Lastly, the tailed lignin nanoparticles (T-LNP) composited with, respectively, polyvinyl alcohol, chitosan, cellulose nanofibers, cationic etherified starch, and sodium alginate were successfully prepared. The outstanding UV-shielding and free radical scavenging properties in the above composites showed their great potential in wide applications in packaging materials.

Dome-arrayed chitosan/PVA hydrogel-based solar evaporator for steam generation

Water evaporation systems with solar energy as the primary driving energy have received extensive attention in recent years. This work studies the preparation method and performance of hydrogel evaporators using chitosan and polyvinyl alcohol (PVA) as a framework and carbon nanoparticles (CNPs) as the photothermal material. The evaporation rate of CPC (chitosan/PVA and CNPs) hydrogel obtained reaches 2.28 kg m-2 h-1. Simultaneously, a three-dimensional structure is designed based on the two-dimensional double-layer evaporation system in this study. An evaporator with a tiny-pool structure and a hydrogel with a dome-arrayed structure is designed. These two structures achieve highly efficient evaporation rates of 2.28 kg m-2 h-1 and 3.80 kg m-2 h-1, respectively. These optimized designs improve the evaporation rate of the overall system by ~ 66.7%. The developed evaporation devices provide a promising pathway for developing the double-layer evaporators, which promote the new development of water purification with a solar-driven evaporation system.

Chitosan/PVA Hetero-Composite Hydrogel Containing Antimicrobials, Perfluorocarbon Nanoemulsions, and Growth Factor-Loaded Nanoparticles as a Multifunctional Dressing for Diabetic Wound Healing: Synthesis, Characterization, and In Vitro/In Vivo Evaluation

Diabetic foot ulcers remain one of the most difficult-to-treat complications of diabetes and may seriously threaten the life of patients since it frequently results in limb loss due to amputation, suggesting that an effective therapeutic strategy is still urgently needed. In this study, a chitosan-based heterogeneous composite hydrogel encapsulating perfluorocarbon emulsions, epidermal growth factor (EGF)-loaded chitosan nanoparticles, and polyhexamethylene biguanide (PHMB) named PEENPPCH was developed for diabetic wound healing. The PEENPPCH could sustainably release EGF and PHMB in an ion-rich environment to exert antibacterial effects and promote cell growth for wound repair. In addition, the PEENPPCH can provide anti-inflammatory effects functioned by its main constituent of chitosan. Moreover, the PEENPPCH can proactively offer oxygen delivery through the incorporation of perfluorocarbon and, therefore, is able to alleviate hypoxia conditions on diabetic wounds. These functionalities enabled a markedly enhanced wound healing efficacy on diabetic rats treated with the PEENPPCHs, including thorough re-epithelization, a reduced inflammatory response, faster collagen deposition, and advanced collagen maturation resulting in a 95% of wound closure degree after 15 days that was 12.6% (p < 0.05) higher than the value of the group treated with the commercial dressing HeraDerm. Given the aforementioned advantages, together with the known merits of hydrogels, the developed PEENPPCH is anticipated to be a feasible tool for clinical diabetic wound treatment.

Nanostructured Lipid Carriers-Hydrogels System for Drug Delivery: Nanohybrid Technology Perspective

Advanced hybrid component development in nanotechnology provides superior functionality in the application of scientific knowledge for the drug delivery industry. The purpose of this paper is to review important nanohybrid perspectives in drug delivery between nanostructured lipid carriers (NLC) and hydrogel systems. The hybrid system may result in the enhancement of each component's synergistic properties in the mechanical strength of the hydrogel and concomitantly decrease aggregation of the NLC. The significant progress in nanostructured lipid carriers-hydrogels is reviewed here, with an emphasis on their preparation, potential applications, advantages, and underlying issues associated with these exciting materials.

Lignin reinforced hydrogels with multi-functional sensing and moist-electric generating applications

Hydrogels, including PVA hydrogels, have numerous applications in many fields; however, their poor mechanical strength limits their utilization potential. Lignin, the most abundant aromatic biopolymer in nature from lignocellulosic biomass, is presently under-utilized. Herein, we used lignin to improve strength and impart pH-responsive properties of PVA hydrogel. The lignin reinforced PVA (LRP) hydrogel has a maximum storage modulus of 83.1 kPa, which is much higher than the PVA hydrogel. The LRP hydrogel exhibits great ionic conductivity, mechanical properties, and strain-sensitivity even at -30 °C. The LRP hydrogel is subsequently applied for a moisture-induced electric generator, which delivers a voltage output of 226.6 mV from moisture flow. The eco-friendly, pH responsive, high antifreezing, ionic conductive, strain sensitive, and moist-electric generating hydrogels have potential applications in many fields, including biomedicine, flexible electrodes, pH-responsive switch, strain sensor, and next-generation self-powered device systems.

A synergy between dopamine and electrostatically bound bactericide in a poly (vinyl alcohol) hybrid hydrogel for treating infected wounds

Antibacterial hydrogels have emerged as viable options for battling infections associated with impaired wound healing. It is challenging in developing antibacterial hydrogels that have sustained and stable bactericidal activity while avoiding the use of any agents that may adversely affect safety. In view of this concern, a multi-functional polyvinyl alcohol (PVA)/sodium alginate-dopamine (SA-DA) hydrogel matrix-based wound dressing embedding with bis-quaternary triphenyl-phosphonium salt (BTPP+), that would present long-term intrinsic antimicrobial properties was developed using freeze-thawing (F-T) method herein. DA endows the hydrogel with efficient bacteria capture ability and subsequently the captured bacterial pathogens were in situ killed by electrostatically bound BTPP+, and hence significantly augmented the antibacterial efficacy. Furthermore, DA, co-operating with BTPP+ could promote erythrocyte and platelet aggregation on hydrogels, which ensures hydrogels with improved hemostasis capacity. Thus, this investigation provides a feasible simple avenue for development of long-term intrinsic antimicrobial hydrogel dressings with efficient hemostasis efficacy for infected wounds.

Chitosan as an Underrated Polymer in Modern Tissue Engineering

Chitosan is one of the most well-known and characterized materials applied in tissue engineering. Due to its unique chemical, biological and physical properties chitosan is frequently used as the main component in a variety of biomaterials such as membranes, scaffolds, drug carriers, hydrogels and, lastly, as a component of bio-ink dedicated to medical applications. Chitosan's chemical structure and presence of active chemical groups allow for modification for tailoring material to meet specific requirements according to intended use such as adequate endurance, mechanical properties or biodegradability time. Chitosan can be blended with natural (gelatin, hyaluronic acid, collagen, silk, alginate, agarose, starch, cellulose, carbon nanotubes, natural rubber latex, κ-carrageenan) and synthetic (PVA, PEO, PVP, PNIPPAm PCL, PLA, PLLA, PAA) polymers as well as with other promising materials such as aloe vera, silica, MMt and many more. Chitosan has several derivates: carboxymethylated, acylated, quaternary ammonium, thiolated, and grafted chitosan. Its versatility and comprehensiveness are confirming by further chitosan utilization as a leading constituent of innovative bio-inks applied for tissue engineering. This review examines all the aspects described above, as well as is focusing on a novel application of chitosan and its modifications, including the 3D bioprinting technique which shows great potential among other techniques applied to biomaterials fabrication.

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

Design and Development of Hybrid Hydrogels for Biomedical Applications: Recent Trends in Anticancer Drug Delivery and Tissue Engineering

The applications of hydrogels in biomedical field has been since multiple decades. Discoveries in biology and chemistry render this platform endowed with much engineering potentials and growing continuously. Novel approaches in constructing these materials have led to the production of complex hybrid hydrogels systems that can incorporate both natural and synthetic polymers and other functional moieties for mediated cell response, tunable release kinetic profiles, thus they are used and research for diverse biomedical applications. Recent advancement in this field has established promising techniques for the development of biorelevant materials for construction of hybrid hydrogels with potential applications in the delivery of cancer therapeutics, drug discovery, and re-generative medicines. In this review, recent trends in advanced hybrid hydrogels systems incorporating nano/microstructures, their synthesis, and their potential applications in tissue engineering and anticancer drug delivery has been discussed. Examples of some new approaches including click reactions implementation, 3D printing, and photopatterning for the development of these materials has been briefly discussed. In addition, the application of biomolecules and motifs for desired outcomes, and tailoring of their transport and kinetic behavior for achieving desired outcomes in hybrid nanogels has also been reviewed.

Antimicrobial Double-Layer Wound Dressing Based on Chitosan/Polyvinyl Alcohol/Copper: In vitro and in vivo Assessment

PURPOSE

Today, the development of wounds and their side effects has become a problematic issue in medical science research. Hydrogel-based dressings are some of the best candidates for this purpose due to their ability to keep the wound bed clean, as well as provide proper moisture, tissue compatibility and an antimicrobial effect for wound healing. On the other hand, copper and its compounds have been used experimentally for many years in studies as an antimicrobial substance. Various studies have been performed determining the antimicrobial properties of this element, during which significant effects on infection have been shown.

METHODS

Chitosan/polyvinyl alcohol/copper nanofibers were successfully prepared by incorporating Cu onto a polymer electrospun using an electrospinning technique. A double-layer nanofiber composed of poly(vinyl alcohol) and chitosan incorporated with Cu nanoparticles as a protective layer and a second layer composed of polyvinylpyrrolidone (PVP) nanofibers which was adjacent to the damaged cells was prepared. The prepared nanofiber was characterized by TGA, FT-IR, TEM, SEM-EDS, and X-ray powder diffraction. The antimicrobial efficiency of the nanofibers was demonstrated through biological tests on some Gram-positive and Gram-negative bacteria. Finally, the prepared hydrogel formulations were prepared to evaluate their effect on the healing process of rat open wounds.

RESULTS

In this study, data from SEM, TEM, EDS, and XRD confirmed the formation of uniform fibers with nanodiameters and the presence of Cu nanoparticles onto the electrospun nanofibers. The antibacterial activity of copper was observed against all of the selected bacteria, but the Gram-positive bacteria were more sensitive compared to Gram-negative bacteria.

CONCLUSION

According to the obtained results, the hydrogel wound dressing prepared in this research can be effective in caring for open wounds in the early stages of wound healing and preventing the occurrence of prolonged open wounds.

Kaolin-loaded chitosan/polyvinyl alcohol electrospun scaffold as a wound dressing material: in vitro and in vivo studies

OBJECTIVE

To evaluate the application of a fabricated dressing containing kaolin for skin regeneration in a rat model of excisional wounds.

METHOD

In the present study, kaolin was loaded into electrospun polyvinyl alcohol (PVA)/chitosan polymer blend to develop a composite nanofibrous dressing. To make the yarns, kaolin with weight ratio of 5% was added to PVA/chitosan polymer blend and subsequently formed into nanofibres using the electrospinning method. Scaffolds were evaluated for to their microstructure, mechanical properties, surface wettability, water vapour transmission rate, water-uptake capacity, blood uptake capacity, blood compatibility, microbial penetration test, the number of colonies, and cellular response with the L929 cell line. Rats with full-thickness excisional wounds were treated with kaolin-containing and kaolin-free dressings.

RESULTS

The study showed that rats treated with the kaolin-incorporated mats demonstrated a significant closure to nearly 97.62±4.81% after 14 days compared with PVA/chitosan and the sterile gauze, which showed 86.15±8.11% and 78.50±4.22% of wound closure, respectively. The histopathological studies showed that in the PVA/chitosan/kaolin group, dense and regular collagen fibres were formed, while wounds treated with sterile gauze or PVA/chitosan scaffolds had random and loose collagen fibres.

CONCLUSION

Our results show the potential applicability of PVA/chitosan/kaolin scaffolds as a wound care material.

Investigation on Mecynorhina torquata Drury, 1782 (Coleoptera, Cetoniidae, Goliathini) cuticle: Surface properties, chitin and chitosan extraction

Naturally derived polymers, such as cellulose or chitin, are materials with increasing interest for a sustainable future. Considering the pollution associated with plastics recycling, natural and fully biocompatible materials like cellulose and chitin are becoming increasingly more relevant for sustainable engineering applications. Chitin and highly deacetylated chitin (chitosan) are already implemented in a wide range of materials applications, especially in biomedical fields. One interesting aspect of chitin is that the majority of industrially produced chitin is extracted from shrimp exoskeleton. However, other arthropods can also be investigated as a source of chitin. In this work, we focus on the extraction of chitin and preparation of chitosan from a beetle specie: Mecynorhina torquata. This includes characterization of the native Mecynorhina torquata surfaces and all intermediate surfaces throughout the chitosan extraction procedure. The final product, prepared chitosan, is also characterized using IR, SEM, ash content, and deacetylation degree. In addition, spectacular iridescent surfaces of Mecynorhina torquata are highlighted at the intermediate steps during chitin extraction. Finally, as proof of concept, the isolated chitosan is used to form hydrogel.

Polyvinyl alcohol/chitosan wound dressings loaded with antiseptics

Wound care remains a challenge in healthcare. This work aimed to develop a new polyvinyl alcohol (PVA)/chitosan (Ch) based wound dressing able to ensure protection, hydration and a controlled release of antiseptics, as alternative to actual treatments. Two distinct formulations (1:1 and 3:1, w/w) were prepared, sterilized by autoclaving and characterized concerning surface morphology, degradation over the time, mechanical properties and hydrophilicity. Both dressings revealed adequate properties for the intended purpose. The dressings were loaded with chlorhexidine (CHX) and polyhexanide (PHMB) and the drug release profiles were determined using Franz diffusion cells. The release of PHMB was more sustained than CHX, lasting for 2 days. As the amounts of drugs released by PVA/Ch 1:1 were greater, the biological tests were done only with this formulation. The drug loaded dressings revealed antibacterial activity against S. aureus and S. epidermidis, but only the ones loaded with PHMB showed adequate properties in terms of cytotoxicity and irritability. The application of this elastic dressing in the treatment of wounds in a dog led to faster recovery than conventional treatment, suggesting that the material can be a promising alternative in wound care.

Bucco-Adhesive Film as a Pediatric Proper Dosage Form for Systemic Delivery of Propranolol Hydrochloride: In-vitro and in-vivo Evaluation

Objective

To formulate and assess bucco-adhesive films of propranolol hydrochloride for pediatric use.

Methods

Different films were formulated adopting mucin, polyvinyl alcohol, chitosan and carbopol. A drug/polymer compatibility study was conducted adopting differential scanning calorimetry and Fourier transform infrared spectroscopy. The prepared films were physically investigated for variation of weight, propranolol content, thickness, surface pH, proportion of moisture, folding endurance and mucoadhesion. In vitro drug release study and kinetic analysis of the corresponding data have been conducted. The optimized formulation was selected for a bioavailability study using albino rabbits and adopting a developed HPLC method. The pharmacokinetic parameters of the drug were calculated following administration of the optimized film and the corresponding marketed oral tablets to albino rabbits.

Key Finding

The compatibility study revealed the absence of drug/polymer interaction. The film formulations had suitable mucoadhesive and mechanical properties. The optimized formulation exhibited reasonable drug release that followed Higuchi diffusion pattern. The calculated AUC0-8h presented an enhancement in the bioavailability of propranolol hydrochloride from the selected film formulation by 1.9 times relative to the marketed propranolol oral tablets.

Conclusion

These findings support that propranolol hydrochloride bucco-adhesive film can be considered as a proper effective dosage form for pediatric delivery.

Biopolymers for hydrogels in cosmetics: review

Hydrogels are cross-linked networks of macromolecular compounds characterized by high water absorption capacity. Such materials find a wide range of biomedical applications. Several polymeric hydrogels can also be used in cosmetics. Herein, the structure, properties and selected applications of hydrogels in cosmetics are discussed in general. Detailed examples from scientific literature are also shown. In this review paper, most common biopolymers used in cosmetics are presented in detail together with issues related to skin treatment and hair conditioning. Hydrogels based on collagen, chitosan, hyaluronic acid, and other polysaccharides have been characterized. New trends in the preparation of hydrogels based on biopolymer blends as well as bigels have been shown. Moreover, biopolymer hydrogels employment in encapsulation has been mentioned.