Development and characterization of a double-layer smart packaging system consisting of polyvinyl alcohol electrospun nanofibers and gelatin film for fish fillet.

This study aimed to develop a double-layer film composed of an intelligent, gelatin-based film integrated with active polyvinyl alcohol electrospun nanofibers (PVANFs). Eggplant skin extract (ESE), a colorimetric indicator, was incorporated into the gelatin-based film at varying concentrations ranging from 0 % to 8 % w/w. The gelatin film containing 8 % ESE was identified as the optimal formulation based on its superior color indication, water barrier, and mechanical properties. Savory essential oil (SEO)-loaded PVANFs were electrospun onto the optimized gelatin film to fabricate the double-layer film. Analysis of the chemical and crystalline structures and the double-layer film's thermal properties confirmed the gelatin film's physical integration with PVANFs. Morphological examination revealed a smooth surface on the film and a uniform fibrillar structure within the PVANFs. Furthermore, the developed double-layer film effectively detected spoilage in trout fish while controlling pH, oxidation, and microbial changes during storage.

Bimetallic Fe/Co-MOF dispersed in a PVA/chitosan multi-matrix hydrogel as a flexible sensor for the detection of lactic acid in sweat samples.

A novel bimetallic Fe/Co-metal-organic framework (MOF) hydrogel-based wearable sweat sensor was developed. Morphological and structural analysis of the hydrogel shows uniformly sized spines and spindle-shaped particles of the Fe/Co-MOF, and it has a high surface area (132.306 m2 g-1) and porosity (0.059 cm3 g-1) as confirmed by Brunauer-Emmett-Teller (BET) studies. The integration of the bimetallic MOF into a polyvinyl alcohol/chitosan (PVA/CS)-mixed matrix resulted in a multiple network hydrogel. The optimisation study investigated  the effects of different pH of the PBS electrolyte, scan rates, and accumulation time in voltammetry. The electrochemical methods such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) provided information on the redox behaviour, electrochemical stability, and catalytic activity of the hydrogel. The sensor demonstrates a wide linear detection range from 0.05 µM to 100 mM, a superior sensitivity of 0.02 mA mM-1 cm-2, and a lower limit of detection of 0.01 µM . Active sites distributed over the hydrogel surface, specifically Fe2+ and Co2+ within the MOF structure, catalyse the oxidation of L-lactic acid, resulting in electron transfer and the formation of pyruvic acid. Notably, the fabricated sensor exhibits high selectivity, effectively discriminating against interfering species such as uric acid, ascorbic acid, glucose, urea, dopamine, NaCl, and CaCl2. Real-time analysis conducted in a simulated sweat sample via the standard addition method resulted in good recovery percentages of a minimum of 98%. The work presented here is a versatile and simple platform for point-of-care testing, especially for athletes and military personnel.

Fabrication and Application of Tannin Double Quaternary Ammonium Salt/Polyvinyl Alcohol as Efficient Sterilization and Preservation Material for Food Packaging.

Food packaging films play a vital role in preserving and protecting food. The focus has gradually shifted to safety and sustainability in the preparation of functional food packaging materials. In this study, a bisquaternary ammonium salt of tannic acid (BQTA) was synthesized, and the bioplastics based on BQTA and polyvinyl alcohol (PVA) were created for packaging applications. The impact of BQTA on antibacterial effect, antioxidant capacity, opacity, ultraviolet (UV) protective activity, mechanical strength, thermal stability, and anti-fog of the resultant bioplastics was examined. In vitro antibacterial experiments confirmed that BQTA possesses excellent antimicrobial properties, and only a trace amount addition of BQTA in PVA composite film could inhibit about 100% of Escherichia coli and Staphylococcus aureus. Compared to BQTA/PVA bioplastics with pure PVA, the experiment findings demonstrate that BQTA/PVA bioplastics show strong antioxidant and UV protection action and the performance of fruit preservation. It also revealed a small improvement in thermal stability and tensile strength. The small water contact angle, even at low BQTA concentrations, gave BQTA/PVA bioplastics good anti-fog performance. Based on the findings, bioplastics of BQTA/PVA have the potential to be used to create packaging, and they can be applied as the second (inner) layer of the primary packaging to protect food freshness and nutrition due to their antioxidant activity and biocompatibility.

Formulation and Development of Nanofiber-Based Ophthalmic Insert for the Treatment of Bacterial Conjunctivitis.

A novel ophthalmic delivery system utilizing levofloxacin-loaded, preservative-free, nanofiber-based inserts was investigated. Polyvinyl alcohol (PVA) and Poloxamer 407 (Polox)were employed as matrix materials, while hydroxypropyl-beta-cyclodextrin (HP-ß-CD) was a solubilizer. The formulations were prepared via electrospinning and characterized for fiber morphology, drug dissolution, cytotoxicity, and antimicrobial activity. Scanning electron microscopy confirmed uniform fibrous structures. Fourier Transform Infrared spectroscopy and X-ray diffraction analyses demonstrated the amorphous state of levofloxacin within the fibers. In vitro dissolution studies revealed a rapid (within 2 min) and complete drug release, with higher HP-ß-CD levels slightly delaying the release. Cytotoxicity tests showed increased HP-ß-CD concentrations induced irritation, that was mitigated by sodium hyaluronate. The antimicrobial efficacy of the nanofibers was comparable to conventional eye drops, with lower minimum inhibitory concentrations for most tested strains. The nanofibrous formulation prepared from a PVA-Polox-based viscous solution of the drug:CD 1:1 mol ratio, containing 0.4% (w/w) sodium hyaluronate) was identified as a particularly promising alternative formulation due to its rapid and complete dissolution, good biocompatibility, and effective antimicrobial properties. Its gelling properties indicate that the residence time on the eye surface can be increased, potentially reducing discomfort and enhancing therapeutic outcomes. The nanofibrous formulations enhanced antimicrobial efficacy, providing a preservative-free alternative that minimizes the potential eye irritation that might occur because of the preservative agent and reduces the administrated dose frequency by extending the drug's retention time on the eye's surface. Subsequently, it improves patients' adherence, which would reflect positively on the bioavailability. The levofloxacin-HP-ß-CD nanofibers demonstrate promise as an alternative to traditional eye drops, offering advantages in solubility, stability, and patient compliance for ocular infection treatment.

Polyvinyl Alcohol Capped Silver Nanostructures for Fortified Apoptotic Potential Against Human Laryngeal Carcinoma Cells Hep-2 Using Extremely-Low Frequency Electromagnetic Field.

Purpose: : Polyvinyl alcohol-capped silver nanostructures (cAgNSs) were investigated in order to enhance the cytotoxicity, pro-apoptotic, and oxidant patterns of in human laryngeal carcinoma Hep-2 cells by employing a 50 mT electromagnetic field (LEMF) for 30 min. Methods: Wet chemical reduction was used to synthesize the cAgNSs, and after they had been capped with polyvinyl alcohol, they were specifically examined for particle size analysis and structural morphology. To visualize how the silver may attach to the protein targets, a molecular docking study was conducted. Estimation of cytotoxicity, cell cycle progression supported by mRNA expression of three apoptotic-promoting genes and one apoptotic-resisting. Results: Particle size analysis results were a mean particle size of 157.3±0.5 nm, zeta potential value of -29.6 mV±1.5 mV, and polydispersity index of 0.31±0.05. Significantly reduction of IC50 against Hep-2 cells by around 6-fold was concluded. Also, we obtained suppression of the proliferation of Hep-2 cells, especially in the G0/G1 and S phases. Significant enhanced mRNA expression revealed enhanced induced CASP3, p53, and Beclin-1 mediated pro-apoptosis and induced NF-κB mediated autophagy in Hep-2 cells. Augmented levels of GR, ROS and MDA as oxidative stress biomarkers were also obtained. HE staining of Hep-2 cells exposed to cAgNSs and LEMF confirmed the enhanced apoptotic potential comparatively. Conclusion: By conclusion, the developed nano-sized structures with the aid of extremely-low frequency electromagnetic field were successful to fortify the anti-cancer profile of cAgNSs in Hep-2 cells.

3D-Printed Hydrogels with Engineered Nanocrystalline Domains as Functional Vascular Constructs.

Three-dimensionally printed (3DP) hydrogel-based vascular constructs have been investigated in response to the impaired function of blood vessels or organs by replicating exactly the 3D structural geometry to approach their function. However, they are still challenged by their intrinsic brittleness, which could not sustain the suture piercing and enable the long-term structural and functional stability during the direct contact with blood. Here, we reported the high-fidelity digital light processing (DLP) 3D printing of hydrogel-based vascular constructs from poly(vinyl alcohol)-based inks, followed by mechanical strengthening through engineering the nanocrystalline domains and subsequent surface modification. The as-prepared high-precision hydrogel vascular constructs were imparted with highly desirable mechanical robustness, suture tolerance, swelling resistance, antithrombosis, and long-term patency. Notably, the hydrogel-based bionic vein grafts, with precise valve structures, exhibited excellent control over the unidirectional flow and successfully fulfilled the biological functionalities and patency during a 4-week implantation within the deep veins of beagles, thus corroborating the promising potential for treating chronic venous insufficiency.

Vanillin loaded-physically crosslinked PVA/chitosan/itaconic membranes for topical wound healing applications.

Vanillin loaded-physically crosslinked hydrogel membranes made of PVA/chitosan/itaconic acid (PVA-CS-IA) were prepared using freezing-thawing (F-T) cycle method. To ensure the entanglement of PVA-CS-IA chains, three F-T cycles were repeated. The polymeric chains entanglements were confirmed and characterized by different instrumental characterizations. Physicochemical properties for example, swelling ratio, mechanical characteristics, gel fraction percentage (GF%), hydrolytic degradation, and thermal stability of PVA-CS-IA membrane were discussed in detail. The findings showed that the swelling ratio, mechanical characteristics, and hydrolytic degradation of the crosslinked membranes enhanced with increasing CS-IA contents in membranes composition; however, GF% gradually declined with CS-IA content. Additionally, cell viability test using HFB-4 cell line and antimicrobial activity against Staphylococcus aureus and Escherichia coli were evaluated using MTT assay and the bacterium growth inhibition percentage method; respectively. Notably, with varying incubation durations and membrane concentrations, all examined constructed hydrogels showed significant cell survival percentages. The findings supported the notion that produced hydrogel membranes might be used in a professional setting as antibacterial dressings or biomaterials for quick wound healing rate.

Prolonged retention of luliconazole nanofibers for topical mycotic condition: development, in vitro characterization and antifungal activity against Candida albicans.

An antifungal agent, luliconazole, is commercially available in cream or gel form. The major limitation of these conventional formulations is less residence time at the infection site. The primary objective of this work was to develop luliconazole-loaded polyvinyl alcohol (Luz-PVA) nanofibers for mycotic skin conditions with a longer retention. Luz-PVA nanofibers were prepared by plate electrospinning and optimized for polymer concentration and process parameters. The optimized batch (Trial 5) was prepared by 10% PVA, processed at 22.4 kV applied voltage, and 14 cm plate and spinneret distance to yield thick, uniform, and peelable nanofibers film. There was no interaction observed between Luz and PVA in the FTIR study. DSC and XRD analysis showed that luliconazole was loaded into fabricated nanofibers with a reduced crystallinity. FESEM studies confirmed the smooth, defect-free mats of nanofibers. Luz-PVA nanofibers possessed a tensile strength of 21.8 N and a maximum elongation of 10.8%, representing the excellent elasticity of the scaffolds. For Luz-PVA nanofibers, the sustained and complete drug release was observed in 48 h. In antifungal activity using Candida albicans, the Luz-PVA nanofibers showed a greater zone of inhibition (30.55 ± 0.38 mm and 29.27 ± 0.31 mm) than marketed cream (28.06 ± 0.18 mm and 28.47 ± 0.24 mm) and pure drug (27.57 ± 0.17 mm and 27.50 ± 0.47 mm) at 1% concentration in Sabouraud dextrose agar and yeast malt agar, respectively. Therefore, Luz-PVA nanofibers exhibited good mechanical properties, longer retention time, and better antifungal activity than marketed products and, therefore, can be further examined preclinically as a potential treatment option for topical mycotic infection.

Promoting the healing of infected diabetic wound by nanozyme-containing hydrogel with anti-bacterial inflammation suppressing, ROS-scavenging and oxygen-generating properties.

Bacterial infections already pose a significant threat to skin wounds, especially in diabetic patients who have difficulty healing wounds. However, wound or bacterial infections are known to produce excess reactive oxygen species (ROS), and hypoxia may further hinder wound healing and the development of chronic wounds. In this study, a multifunctional hydrogel for ROS scavenging and bacterial inhibition was developed by cross-linking polyvinyl alcohol (PVA) and sodium alginate (SA) with graphene oxide (GO) loaded with silver-platinum hybrid nanoparticles (GO@Ag-Pt). The PVA/SA hydrogel loaded with GO@Ag-Pt exhibited the ability to scavenge different types of ROS, generate O2, and kill a broad spectrum of bacteria in vitro. The silver-platinum hybrid nanoparticles significantly increased the antibacterial ability against Escherichia coli and Staphylococcus aureus compared with silver nanoparticles (AgNps). GO@Ag-Pt loaded hydrogel was effective in treating infections caused by S.aureus, thereby significantly promoting wound healing during the inflammatory phase. Hydrogel therapy significantly reduced the level of ROS and alleviated inflammation levels. Notably, our ROS-scavenging, antibacterial hydrogels can be used to effectively treat various types of wounds, including difficult-to-heal diabetic wounds with bacterial infections. Thus, this study proposes an effective strategy for various chronic wound healing based on ROS clearance and bacteriostatic hydrogels.

Antimicrobial effect of two fluoride-releasing adhesive tapes on Streptococcus mutans biofilm.

Fluoride-releasing adhesive tapes have been developed as a new fluoride delivery agent. However, application as caries prevention agents remains underexplored. This study aimed at evaluating the antimicrobial activity of two fluoride-releasing adhesive tapes against S. mutans biofilm. Two polyvinyl alcohol (PVA) tapes were investigated: (i) a fluoride-PVA (F-PVA) tape, (ii) a pullulan incorporated F-PVA (PF-PVA) tape. S. mutan strains were cultured and treated with the tapes. Antimicrobial effects were evaluated using the agar diffusion test, field-emission scanning electron microscopy (FE-SEM), and confocal laser scanning microscopy (CLSM). F-PVA tapes showed higher inhibition-zone diameters than PF-PVA at 48 h and 72 h. However, there were no significant differences (p > 0.05) between the effects of F-PVA and PF-PVA. The bio-volume of S. mutans and extracellular polymeric substances significantly decreased in the F-PVA tapes than in the PF-PVA tapes (p < 0.05). FE-SEM micrographs revealed less S. mutans colonization in F-PVA. F-PVA exhibited better antimicrobial activity against S. mutans than PF-PVA.

Sustainable synthesis of fluorescent polymer carbon dots@PVA for sensitive chlortetracycline detection.

Antibiotic residues persist in the environment and represent serious health hazards; thus, it is important to develop sensitive and effective detection techniques. This paper presents a bio-inspired way to make water-soluble fluorescent polymer carbon dots (PCDs@PVA) by heating biomass precursors and polyvinyl alcohol (PVA) together. For example, the synthesized PCDs@PVA are very stable with enhanced emission intensity. This property was observed in a wide range of environmental conditions, including those with changing temperatures, pH levels, UV light, and ionic strength. PCDs@PVA detected the antibiotic chlortetracycline (CTCs) with great selectivity against structurally related compounds and a low detection limit of 20 nM, demonstrating outstanding sensitivity and specificity. We confirmed the sensor's practical application through real sample analysis, yielding recovery rates of 98%-99% in samples of milk, honey, and river water. The synthesized PCDs@PVA fluorescence sensor was successfully used for CTCs detection in real samples.

Formulations of poly(vinyl alcohol) functionalized silk fibroin nanoparticles for the oral delivery of zwitterionic ciprofloxacin.

Fibroin nanoparticles (FNP) have been employed in numerous biomedical applications. However, limited research has focused on the oral delivery of FNP and in-depth molecular interactions between the encapsulated drug and FNP. Therefore, this work developed the FNP, functionalized with poly(vinyl alcohol) (PVA), to orally deliver the zwitterionic ciprofloxacin, focused on the molecular interactions. The particles were formulated using both desolvation (the drug precipitated during the particles formulation) and adsorption (the drug adsorbed on the particles surfaces) methods. The optimal formula possessed a size of ~630 nm with narrow size distribution (measured by DLS method), spherical shape (determined by SEM), and moderate drug loading (confirmed by FT-IR, XRD, and DSC techniques) of ~50% for the desolvation method and ~43% for the adsorption method. More than 80% of the drug molecules resided on the particle surfaces, mainly via electrostatic forces with fibroin. The drug was physically adsorbed onto FNP, which followed Langmuir model and pseudo second-order kinetics. In the in-vitro simulated gastric condition at pH 1.2, the ciprofloxacin bound strongly with FNP via electrostatic forces, thus hindering the drug release (< 40%). Contrastingly, in the simulated intestinal condition at pH 6.8, the particles could control the drug release rates dependent on the PVA amount, with up to ~100% drug release. Lastly, the particles possessed adequate antibacterial activities on Bacillus subtilis, Escherichia coli, and Salmonella enterica, with MIC of 128, 8, and 32 µg/mL, respectively. In summary, the FNP and PVA functionalized FNP could be a potential oral delivery system for zwitterionic drugs.

Engineering the nanozyme hydrogel beads by polyvinyl alcohol/chitosan encapsulation with recyclable and sustainable catalytic activity for visual analysis of hydrogen peroxide.

BACKGROUND: Hydrogen peroxide (H2O2) plays a vital role in human health and have been regarded as a crucial analyte in metabolic processes, redox transformations, foods research and medical fields. Especially, the long-time and excessive digestion of H2O2 may even cause severe diseases. Although conventional instrumental methods and nanozymes-based colorimetric methods have been developed to accomplish the quantitative analysis of H2O2, the drawbacks of instrument dependence, cost-effectiveness, short lifespan, non-portable and unsustainable detection efficacies will limit their applications in different detection scenarios. RESULTS: Herein, to address these challenges, we have proposed a novel strategy for nanozyme (RuO2) hydrogel preparation by the solid support from cross-linked polyvinyl alcohol (PVA) and chitosan (CS) to both inherit the dominant peroxidase-like (POD) activity and protect the RuO2 from losing efficacies. Taking advantages from the hydrogel, the encapsulated RuO2 were further prepared as the regularly spherical beads (PCRO) to exhibit the sustainable, recyclable, and robust catalysis. Moreover, the intrinsic color interferences which originated from RuO2 can be avoided by the encapsulation strategy to promote the detection accuracy. Meanwhile, the high mechanical strength of PCRO shows the high stability, reproducibility, and cyclic catalysis to achieve the recyclable detection performance and long lifetime storage (40 days), which enables the sensitively detection of H2O2 with the detection limit as lower to 15 µM and the wide detection linear range from 0.025 to 1.0 mM. SIGNIFICANCE: On the basis of the unique properties, PCRO has been further adopted to construct a smartphone detection platform to realize the instrument-free and visual analysis of H2O2 in multi-types of milk and real water samples through capturing, processing, and analyzing the RGB values from the colorimetric photographs. Therefore, PCRO with the advanced detection efficacies holds the great potential in achieving the portable and on-site analysis of targets-of-interest.

Excellent Antibacterial Properties of Silver/Silica-Chitosan/Polyvinyl Alcohol Transparent Film.

Transparent films with excellent antibacterial properties and strong mechanical properties are highly sought after in packaging applications. In this study, Ag/SiO2 nanoparticles were introduced into a mixed solution of chitosan (CS) and polyvinyl alcohol (PVA) and a Ag/SiO2-CS-PVA transparent film was developed. The excellent properties of the film were confirmed by light transmittance, water contact angle tests and tensile tests. In addition, for the antibacterial test, the antibacterial properties of the sample against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were explored, and the average size of the bacteriostatic circle was measured by the cross method. The final results show that Ag/SiO2-CS-PVA transparent film has the advantages of good antibacterial properties, high transparency and high mechanical strength.

[Bacterial Blocking and Repair of Intestinal Defects With Well-Alighed Lamellar MXene/Polyvinyl Alcohol Hydrogels Prepared by Bidirectional Freezing Method]. / 双向冷冻法制备的取向多层MXene/PVAæ°´å‡èƒ¶çš„ç»†èŒå±è”½ä½œç”¨åŠå¯¹è‚ é“ç¼ºæŸçš„ä¿®å¤.

Objective: To explore the bacterial blocking effect of oriented multilayer MXene/polyvinyl alcohol (PVA) nanocomposite hydrogels and their effect on the repair of intestinal defects. Methods: MXene/PVA nanocomposite hydrogels were prepared using the traditional freezing method and the bidirectional freezing ice template method. The structures of the different hydrogels were observed using scanning electron microscopy (SEM) and micro-CT reconstruction. The rheological properties of the hydrogels were measured using a dynamic rheometer, and their mechanical properties were assessed using a universal testing machine. The burst pressure of the hydrogels was determined through burst experiments, and bacterial colony growth was observed by the osmosis method to assess the bacteria blocking ability of the hydrogels in vitro. A rat model of cecal perforation was established, and the hydrogels were used for intestinal repair. Gram staining was performed to observe in vivo the bacterial blocking ability of the hydrogels, HE staining was performed to observe the intestinal inflammation, and CD31 and CD68 immunofluorescence staining and proliferating cell nuclear antigen (PCNA) staining were performed to observe the repair effect of the hydrogels on intestinal defects. Results: SEM and micro-CT reconstruction revealed that the hydrogel prepared by the traditional freezing method exhibited a random porous structure, while the hydrogel prepared by the bidirectional freezing method showed an oriented multilayer structure. Rheological and tensile tests indicated that the oriented hydrogel had superior mechanical properties, and the burst pressure of the oriented multilayer hydrogel was as high as 27 kPa, significantly higher than that of the non-oriented hydrogel (P<0.001). Bacterial colony growth was observed by the osmosis method and it was found that, compared with the non-oriented hydrogel, the oriented multilayer hydrogel could effectively prevent the infiltration of Escherichia coli and Staphylococcus aureus in vitro. Gram staining results showed that the oriented multilayer hydrogel could effectively block intestinal bacteria from entering the abdominal cavity in vivo. HE staining results showed that the oriented multilayer hydrogel could effectively reduce intestinal inflammation in vivo. CD31 and CD68 immunofluorescence staining and PCNA staining results showed that the oriented multilayer hydrogel had a repairing effect on intestinal defects in vivo. Conclusion: The oriented multilayer hydrogel prepared by bidirectional freezing effectively prevents bacterial infiltration and reduces intestinal inflammation.

Fabrication of multifunctional ZnO@tannic acid nanoparticles embedded in chitosan and polyvinyl alcohol blend packaging film.

The current study explores biodegradable packaging materials that have high food quality assurance, as food deterioration is mostly caused by UV degradation and oxidation, which can result in bad flavor and nutrition shortages. Thus, new multifunctional zinc oxide nanoparticles/tannic acid (ZnO@TA) with antioxidant and antibacterial activities were incorporated into polyvinyl alcohol/chitosan (PVA/CH) composite films with different ratios (1%, 3%, and 5% based on the total dry weight of the film) via a solution blending method in a neutral aqueous solution. Additionally, ZnO nanoparticles have unique antibacterial mechanisms through the generation of excessive reactive oxygen species (ROS) that may lead to intensify pathogen resistance to conventional antibacterial agents. Thus, minimizing the negative effects caused by excessive levels of ROS may be possible by developing unique, multifunctional ZnO nanoparticles with antioxidant potential via coordination bond between tannic acid and ZnO nanoparticles (ZnO@TA). ZnO@TA nanoparticles were examined using Fourier-transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effect of the incorporation of ZnO@TA nanoparticles on the barrier, mechanical, thermal, antioxidant, antimicrobial, and UV blocking characteristics of chitosan/polyvinyl alcohol (ZnO@TA@CH/PVA) films was investigated. The lowest water vapor and oxygen permeability and the maximum antioxidant capacity% are 31.98 ± 1.68 g mm/m2 kPa day, 0.144 ± 5.03 × 10-2 c.c/m2.day, and 69.35 ± 1.6%, respectively, which are related to ZnO@TA(50)@CH/PVA. Furthermore, ZnO@TA(50)@CH/PVA film exhibits the maximum UV shielding capacity of UVB (99.994). ZnO@TA(50) @PVA/CH films displayed better tensile strength and Young`s modulus of 48.72 ± 0.23 MPa and 2163.46 ± 61.4 MPa, respectively, than the other film formulations. However, elongation % at break exhibited the most reduced value of 19.62 ± 2.3%. ZnO@TA@CH/PVA film exhibits the largest inhibition zones of 11 ± 1.0, 12.3 ± 0.57, and 13.6 ± 0.57 mm against Staphylococcus aureus, Aspergillus flavus, and Candida albicans, respectively. In accordance with these results, ZnO@TA@CH/PVA films could be utilized for food preservation for the long-term.

Synthesis and analysis of multifunctional graphene oxide/Ag2O-PVA/chitosan hybrid polymeric composite for wound healing applications.

The requirement for accurate treatments for skin diseases and wounds, generated a rising interest towards multifunctional polymer composites, that are capable of mimicking the natural compositions in human body. Also, electroactive composite films disseminate endogenous electrical stimulations that encourage cell migration and its proliferation at wound site, proposing greater opportunities in upgrading the conventional wound patches. In this work, the composite film made of graphene oxide, Ag2O, PVA and chitosan were developed for wound healing applications, by the solution casting method. The even dispersibility of nanofiller in polymeric matrix was validated from the physicochemical analyses. The increment in roughness of the composite film surface was noted from AFM images. The thermal stability and porous nature of the polymer composite were also verified. A conductivity value of 0.16 × 10-4 Scm-1 was obtained for the film. From MTT assay, it was noted that the films were non-cytotoxic and supported cell adhesion along with cell proliferation of macrophage (RAW 264.7) cells. Moreover, the composite film also demonstrated non-hemolytic activity of <2 %, as well as excellent antibacterial activity towards E. coli and S. aureus. Thus, the obtained results validated that the prepared composite film could be chosen as an innovative candidate for developing state-of-the-art wound dressings.

Fabrication and characterization of polyvinyl alcohol-chitosan composite nanofibers for carboxylesterase immobilization to enhance the stability of the enzyme.

Electrospinning stands out as a flexible and viable method, presenting designed nanoscale materials with customized properties. This research demonstrates the immobilization of carboxylesterase protein Ha006a, reported for its adequacy in pesticide bioremediation by utilizing the electrospinning strategy. This strategy was utilized to create nanofibers by incorporating variable mixtures of biodegradable and cost-effective polyvinyl alcohol (PVA)-chitosan (CS) nanofiber solution (PVA100, PVA96, PVA94, PVA92 and PVA90). All the mixtures were electrospun at a reliable voltage of 21 kV, maintaining a gap of 12 cm from the nozzle. The Ha006a, sourced from Helicoverpa armigera, was consolidated into the optimized PVA90 polymer mixture. The electrospun nanofibers experienced comprehensive characterization utilizing distinctive microscopy and spectroscopy procedures counting FESEM, TGA, XRD and FTIR. The comparative investigation of the esterase property, ideal parameters and stability of the unbound and bound/immobilized Ha006a was scrutinized. The results uncovered an essential elevation in the ideal conditions of enzyme activity post-immobilization. The PVA-CS control nanofiber and Ha006a-PVA-CS showed a smooth structure, including an average breadth of around 170.5 ± 44.2 and 222.5 ± 66.5 nm, respectively. The enzyme-immobilized nanofibers displayed upgraded stability and comprehensive characterization of the nanofiber, which guaranteed genuineness and reproducibility, contributing to its potential as a potent device for bioremediation applications. This investigation opens the way for the manufacture of pesticide-resistant insect enzyme-based nanofibers, unlocking their potential for assorted applications, counting pesticide remediation and ensuring environmental sustainability.

Tunicate cellulose nanocrystals strengthened injectable stretchable hydrogel as multi-responsive enhanced antibacterial wound dressing for promoting diabetic wound healing.

The intricate microenvironment of diabetic wounds characterized by hyperglycemia, intense oxidative stress, persistent bacterial infection and complex pH fluctuations hinders the healing process. Herein, an injectable multifunctional hydrogel (QPTx) was developed, which exhibited excellent mechanical performance and triple responsiveness to pH, temperature, and glucose due to dynamic covalent cross-linking involving dynamic Schiff base bonds and phenylboronate esters with phenylboronic-modified quaternized chitosan (QCS-PBA), polydopamine coated tunicate cellulose crystals (PDAn@TCNCs) and polyvinyl alcohol (PVA). Furthermore, the hydrogels can incorporate insulin (INS) drugs to adapt to the complex and variable wound environment in diabetic patients for on-demand drug release that promote diabetic wound healing. Based on various excellent properties of the colloidal materials, the hydrogels were evaluated for self-healing, rheological and mechanical properties, in vitro insulin response to pH/temperature/glucose release, antibacterial, antioxidant, tissue adhesion, coagulation, hemostasis in vivo and in vitro, and biocompatibility and biodegradability. By introducing PDAn@TCNCs particles, the hydrogel has photothermal antibacterial activity, enhanced adhesion and oxidation resistance. We further demonstrated that these hydrogel dressings significantly improved the healing process compared to commercial dressings (Tegaderm™) in full-layer skin defect models. All indicated that the glucose-responsive QPTx hydrogel platform has great potential for treating diabetic wounds.

Room temperature luminescence of 1,N2-etheno-2-aminopurine in poly (vinyl alcohol) films.

We studied spectral properties of 1,N2-etheno-2-aminopurine after immobilization in poly (vinyl alcohol) films. The absorption spectrum of 1,N2-ε2APu consists of two peaks centered at 300 and 370 nm, and the fluorescence spectrum has maximum at about 460 nm. The fluorescence quantum efficiency is 62%. The fluorescence anisotropy reaches a value of 0.3 at longer wavelengths, while it is low at shorter wavelengths (corresponding to the second single excited state). The 1,N2-ε2APu has a relatively long fluorescence lifetime of about 16 ns and a noticeable room temperature phosphorescence with a lifetime of about 220 ms. A broad phosphorescence emission band (425-675 nm) is centered at about 530 nm and markedly overlaps with fluorescence at shorter wavelengths. Surprisingly, the phosphorescence excitation spectrum of 1,N2-ε2APu-doped poly (vinyl alcohol) film differs from the absorption and fluorescence excitation spectra. The strongest room temperature phosphorescence excitation is about 335 nm. At longer excitation wavelengths, above 450 nm, where fluorescence cannot be excited, a triplet excitation is still possible. The 1,N2-ε2APu phosphorescence anisotropy spectra confirm direct triplet state excitation. The ability to excite molecules at long wavelengths can find applications in the study of biological molecules that are unstable when excited at high energies.