Biomaterials of Poly(vinyl alcohol) and Natural Polymers

V, Kumarswamy YK, Raghu MS, T. VG, Nandihalli N, Kasai DR. Poly(vinyl alcohol) Nanocomposites Reinforced with CuO Nanoparticles Extracted by Ocimum sanctum: Evaluation of Wound-Healing Applications

This study focused on the synthesis of plant-mediated copper-oxide nanoparticles (OsCuONPs) via the sol-gel technique and the fabrication of OsCuONP-infused PVA composite films (POsCuONPs) utilizing the solvent casting method for wound-healing applications. The prepared OsCuONPs and nanocomposite films were characterized using UV-visible spectra, FTIR, SEM, XRD, TGA, water contact-angle (WCA) measurements, and a Universal testing machine (UTM) for mechanical property measurements. The UV and FTIR tests showed that OsCuONPs were formed and were present in the PVA composite film. Moreover, the mechanical study confirmed that there is an increase in the tensile strength (TS) and Young's modulus (Ym) with 21.75 MPa to 32.50 MPa for TS and 24.80 MPa to 1128.36 MPa for Ym, and a decrease in the % elongation at break (Eb) (394.32 to 75.6). The TGA and WCA study results demonstrated that PVA films containing OsCuONPs are more stable when subjected to high temperatures and demonstrate a decreased hydrophilicity (60.89° to 89.62°). The cytotoxicity and hemolysis tests showed that the CuONPs-3 containing composite films (PVA/OsCuONPs with a wt. ratio of 1.94/0.06) are safe to use, have a good level of cell viability, and do not break down blood. This is true even at high concentrations. The study also discovered that cells moved considerably in 12 and 24 h (13.12 to 19.26 for OsCuONPs and 312.53 to 20.60 for POsCuONPs), suggesting that 60% of the gaps were filled. Therefore, the fabricated POsCuONP nanocomposites may serve as a promising option for applications in wound healing.

Properties of Electrospun Fibers That Influence Foreign Body Response Modulation

Improving the utility of biomedical devices implanted in subcutaneous tissue by modulating the innate immune response common to these implants is of great interest to improve their utility. Uncontrolled, most biomedical devices produce an immune reaction known broadly as the foreign body response (FBR), which ultimately isolates the device from the native tissue. The use of electrospun fibers to create a porous surface that promotes tissue in-growth and regeneration represents a new paradigm in FBR modulation. A vast number of parameters can be adjusted in the electrospinning process to tune the type and quality of the resulting electrospun matrix, which in turn has varying outcomes with respect to the FBR. In this review, the fabrication and utility of electrospun fiber scaffolds for mitigating the FBR are described, with details of how fiber properties and surface modifications alter immune response for specific biomedical applications.

Construction of chitosan/carboxylated polyvinyl alcohol/poly(N-isopropylacrylamide) composite antibacterial hydrogel for rapid wound healing

In the realm of skin injury management, the expedited closure of wounds, prevention of scar formation, and enhancement of the healing process are of critical significance. The creation of economical dressings that effectively facilitate swift wound sealing in the initial phase of skin trauma while curbing scar development represents a promising avenue for clinical utility. Within the context of this investigation, we synthesized a novel hydrogel composed of chitosan (CS), carboxylated poly(vinyl alcohol) (PVA-COOH) via a Schiff base reaction between carboxylated PVA and chitosan, yielding networks abundant in amide bonds. Following this, a chitosan/carboxylated PVA/poly(N-isopropylacrylamide) hydrogel (CNP) was engineered by incorporating poly-N-isopropylacrylamide chains for interpenetration at ambient temperature. Our findings indicate that the CNP hydrogel exhibits favorable degradability and swelling characteristics. Moreover, it possesses favorable antimicrobial efficacy and biocompatibility. In a murine full-thickness skin injury model, the hydrogel was found to expedite wound healing by augmenting granulation tissue formation, mitigating wound inflammation, and promoting angiogenesis.

Biodegradation profile and soil microbiota interactions of poly(vinyl alcohol)/starch-based fertilizers

Enhanced efficiency fertilizers (EEFs) are critical for sustainable agriculture, providing essential nutrients while minimizing environmental impact. However, developing EEFs that effectively degrade after use remains a significant challenge. This study investigates the biodegradation and nutrient release profiles of EEFs composed of poly(vinyl alcohol) (PVA) and starch-nutrient microspheres. EEFs were developed using a dual-layered approach: spray drying to create starch-nutrient microspheres, followed by melt processing with PVA to form pastilles. A 100-day soil biodegradation test monitored CO2 release as an indicator of microbial activity and material degradation. Comprehensive analyses, including chemical (FTIR), thermal (DSC), and morphological (SEM) assessments, were conducted. The increased CO band intensity (~1640 cm-1) after biodegradation indicated early stages of PVA degradation, accompanied by a rise in the glass transition temperature (Tg). Thermal analysis revealed nutrient release, as evidenced by a decrease in KNO3 peaks. Starch-based EEFs enhanced CO2 release and mycelial coverage, suggesting that starch-containing materials facilitated PVA degradation by improving microbial adhesion. This study underscores the potential of biodegradable EEFs to enhance soil health and reduce pollution, thereby contributing significantly to sustainable agriculture.

Enhancing thermal stability and mechanical resilience in gelatin/starch composites through polyvinyl alcohol integration

In practical scenarios, destabilizing the physical attributes of natural polymers such as gelatin and starch occurs readily when exposed to specific moisture levels and heat. In this context, this work was carried out to assess the impact of PVA addition (up to 13 wt%) on the structure and physical properties of a 6:4 (w/w) gelatin/starch blend. The inclusion of PVA unfolded the molecular chains of gelatin and starch, thereby disrupting gelatin α-helices and impeding biopolymer crystallization. This facilitated hydrogen-bonding interaction between PVA and the two biopolymers, enhancing the stability of the molecular network structure. Rheological results indicate that composites (added with 4 % or 7 % PVA) with good compatibility exhibited excellent mechanical properties and deformation resistance. The addition of PVA elevated the gelling temperature (Tgel) of the composites from 41.31 °C to 80.33 °C; the tensile strength and elongation at break were increased from 2.89 MPa to 3.40 MPa and 341.62 % to 367.56 %, respectively; and the thermal stability was also apparently improved, signifying the effective enhancement of the physical properties of gelatin/starch-based composites and the broadening of their application scope. This work could provide insights into the development of biodegradable natural/synthetic polymer composites with application-beneficial characteristics.

Evaluation of Conductive Porous Biobased Composites with Tunable Mechanical Properties for Potential Biological Applications

In this work, starch-based porous cryogels with controlled mechanical and electrical properties were prepared for tissue engineering applications. The starch cryogels were formulated using κ-carrageenan, poly(vinyl alcohol) (PVA), and styrylpyridinium-substituted PVA (SbQ) into the composite. A conductive cryogel was polymerized by chemical oxidation of 3,4-ethylenedioxythiophene (EDOT) using iron(III) p-toluenesulfonate as a strategy to control the electrical properties. The physical, thermal, and mechanical properties were evaluated for the obtained composites. Macro- and nanoscale results confirmed the capability of tuning the mechanical properties of the material by the addition of biopolymers in different contents. The presence of κ-carrageenan significantly increased the storage modulus and decreased the damping effect in the formulations. The presence of PVA showed a plasticizing effect in the formulations, confirmed by the buffering effect and an increase in storage modulus. PVA-SBQ improved the mechanical properties by cross-linking. The addition of PEDOT increased the mechanical and electrical properties of the obtained materials.

Polyvinyl Alcohol (PVA)-Based Hydrogels: Recent Progress in Fabrication, Properties, and Multifunctional Applications

Polyvinyl alcohol (PVA)-based hydrogels have attracted significant attention due to their excellent biocompatibility, tunable mechanical properties, and ability to form stable three-dimensional networks. This comprehensive review explores the recent advancements in PVA-based hydrogels, focusing on their unique properties, fabrication strategies, and multifunctional applications. Firstly, it discusses various facile synthesis techniques, including freeze/thaw cycles, chemical cross-linking, and enhancement strategies, which have led to enhanced mechanical strength, elasticity, and responsiveness to external stimuli. These improvements have expanded the applicability of PVA-based hydrogels in critical areas such as biomedical, environmental treatment, flexible electronics, civil engineering, as well as other emerging applications. Additionally, the integration of smart functionalities, such as self-healing capabilities and multi-responsiveness, is also examined. Despite progress, challenges remain, including optimizing mechanical stability under varying conditions and addressing potential toxicity of chemical cross-linkers. The review concludes by outlining future perspectives, emphasizing the potential of PVA-based hydrogels in emerging fields like regenerative medicine, environmental sustainability, and advanced manufacturing. It underscores the importance of interdisciplinary collaboration in realizing the full potential of these versatile materials to address pressing societal challenges.

Advancement in Soft Hydrogel Grippers: Comprehensive Insights into Materials, Fabrication Strategies, Grasping Mechanism, and Applications

Soft hydrogel grippers have attracted considerable attention due to their flexible/elastic bodies, stimuli-responsive grasping and releasing capacity, and novel applications in specific task fields. To create soft hydrogel grippers with robust grasping of various types of objects, high load capability, fast grab response, and long-time service life, researchers delve deeper into hydrogel materials, fabrication strategies, and underlying actuation mechanisms. This article provides a systematic overview of hydrogel materials used in soft grippers, focusing on materials composition, chemical functional groups, and characteristics and the strategies for integrating these responsive hydrogel materials into soft grippers, including one-step polymerization, additive manufacturing, and structural modification are reviewed in detail. Moreover, ongoing research about actuating mechanisms (e.g., thermal/electrical/magnetic/chemical) and grasping applications of soft hydrogel grippers is summarized. Some remaining challenges and future perspectives in soft hydrogel grippers are also provided. This work highlights the recent advances of soft hydrogel grippers, which provides useful insights into the development of the new generation of functional soft hydrogel grippers.

Size-tailored and acid-degradable polyvinyl alcohol microgels for inhalation therapy of bacterial pneumonia

Administration of antibiotics via inhalation is considered an effective strategy for pneumonia treatment; however, it encounters challenges related to the development of drug formulations with precise particle sizes and controlled release profiles. Herein, size-tailored and acid-degradable polyvinyl alcohol (PVA) microgels are utilized for nebulized inhalation delivery of piperacillin (PIP) antibiotics to effectively treat pneumonia. These microgels loaded with PIP (G@PIP) were prepared through the UV-crosslinking of thermo-triggered vinyl ether methacrylate-functionalized PVA (PVAVEMA) micro-aggregates in aqueous solution. The size of G@PIP microgels could be tailored by adjusting concentrations during the crosslinking process above phase-transition temperature at 15 °C. Additionally, under simulated inflammatory acidic conditions, the G@PIP microgels degraded and released PIP with relatively high inhibition efficiency against E. coli. Furthermore, in vivo therapeutic outcomes revealed that inhalational delivery of G@PIP microgel with a medium-size of 3.5 μm (G-3.5@PIP) exhibited superior lung deposition compared to other microgel sizes owing to its reduced exhalation and enhanced diffusion capacity within the pulmonary system. The high accumulation of G-3.5@PIP significantly reduced E. coli infection and associated inflammation while maintaining the biocompatibility of the microgels. Overall, these acid-degradable PVA microgels offer a versatile and efficacious inhalation therapy for pneumonia-associated infections.

Wound Dressing with Electrospun Core-Shell Nanofibers: From Material Selection to Synthesis

Skin, the largest organ of the human body, accounts for protecting against external injuries and pathogens. Despite possessing inherent self-regeneration capabilities, the repair of skin lesions is a complex and time-consuming process yet vital to preserving its critical physiological functions. The dominant treatment involves the application of a dressing to protect the wound, mitigate the risk of infection, and decrease the likelihood of secondary injuries. Pursuing solutions for accelerating wound healing has resulted in groundbreaking advancements in materials science, from hydrogels and hydrocolloids to foams and micro-/nanofibers. Noting the convenience and flexibility in design, nanofibers merit a high surface-area-to-volume ratio, controlled release of therapeutics, mimicking of the extracellular matrix, and excellent mechanical properties. Core-shell nanofibers bring even further prospects to the realm of wound dressings upon separate compartments with independent functionality, adapted release profiles of bioactive agents, and better moisture management. In this review, we highlight core-shell nanofibers for wound dressing applications featuring a survey on common materials and synthesis methods. Our discussion embodies the wound healing process, optimal wound dressing characteristics, the current organic and inorganic material repertoire for multifunctional core-shell nanofibers, and common techniques to fabricate proper coaxial structures. We also provide an overview of antibacterial nanomaterials with an emphasis on their crystalline structures, properties, and functions. We conclude with an outlook for the potential offered by core-shell nanofibers toward a more advanced design for effective wound healing.

Recent Advances in the Fabrication and Performance Optimization of Polyvinyl Alcohol Based Vascular Grafts

Cardiovascular disease is one of the diseases with the highest morbidity and mortality rates worldwide, and coronary artery bypass grafting (CABG) is a fast and effective treatment. More researchers are investigating in artificial blood vessels due to the limitations of autologous blood vessels. Despite the availability of large-diameter vascular grafts (Ø > 6 mm) for clinical use, small-diameter vascular grafts (Ø < 6 mm) have been a challenge for researchers to overcome in recent years. Vascular grafts made of polyvinyl alcohol (PVA) and PVA-based composites have excellent biocompatibility and mechanical characteristics. In order to gain a clearer and more specific understanding of the progress in PVA vascular graft research, particularly regarding the preparation methods, principles, and functionality of PVA vascular graft, this article discusses the mechanical properties, biocompatibility, blood compatibility, and other properties of PVA vascular graft prepared or enhanced with different blends using various techniques that mimic natural blood vessels. The findings reveal the feasibility and promising potential of PVA or PVA-based composite materials as vascular grafts.

Immobilized Drugs on Dual-Mode Imaging Ag2S/BaSO4/PVA Embolic Microspheres for Precise Localization, Rapid Embolization, and Local Antitumor Therapy

Transcatheter arterial embolization (TAE) in interventional therapy and tumor embolism therapy plays a significant role. The choice of embolic materials that have good biocompatibility is an essential component of TAE. For this study, we produced a multifunctional PVA embolization material that can simultaneously encapsulate Ag2S quantum dots (Ag2S QDs) and BaSO4 nanoparticles (BaSO4 NPs), exhibiting excellent second near-infrared window (NIR-II) fluorescence imaging and X-ray imaging, breaking through the limitations of traditional embolic microsphere X-ray imaging. To improve the therapeutic effectiveness against tumors, we doped the doxorubicin (DOX) antitumor drug into microspheres and combined it with a clotting peptide (RADA16-I) on the surface of microspheres. Thus, it not only embolizes rapidly during hemostasis but also continues to release and accelerate tumor necrosis. In addition, Ag2S/BaSO4/PVA microspheres (Ag2S/BaSO4/PVA Ms) exhibited good blood compatibility and biocompatibility, and the results of embolization experiments on renal arteries in rabbits revealed good embolic effects and bimodal imaging stability. Therefore, they could serve as a promising medication delivery embolic system and an efficient biomaterial for arterial embolization. Our research work achieves the applicability of NIR-II and X-ray dual-mode images for clinical embolization in biomedical imaging.

Recent Advances in Poly(vinyl alcohol)-Based Hydrogels

Poly(vinyl alcohol) (PVA) is a versatile synthetic polymer, used for the design of hydrogels, porous membranes and films. Its solubility in water, film- and hydrogel-forming capabilities, non-toxicity, crystallinity and excellent mechanical properties, chemical inertness and stability towards biological fluids, superior oxygen and gas barrier properties, good printability and availability (relatively low production cost) are the main aspects that make PVA suitable for a variety of applications, from biomedical and pharmaceutical uses to sensing devices, packaging materials or wastewater treatment. However, pure PVA materials present low stability in water, limited flexibility and poor biocompatibility and biodegradability, which restrict its use alone in various applications. PVA mixed with other synthetic polymers or biomolecules (polysaccharides, proteins, peptides, amino acids etc.), as well as with inorganic/organic compounds, generates a wide variety of materials in which PVA's shortcomings are considerably improved, and new functionalities are obtained. Also, PVA's chemical transformation brings new features and opens the door for new and unexpected uses. The present review is focused on recent advances in PVA-based hydrogels.

Toxicity of water-soluble polymers polyethylene glycol and polyvinyl alcohol for fish and frog embryos

Personal Care Products (PCPs) have been one of the most studied chemicals in the last twenty years since they were identified as pseudo-persistent pollutants by the European Union in the early 2000s. The accumulation of PCPs in the aquatic environment and their effects on non-target species make it necessary to find new, less harmful, substances. Polyethylene glycol (PEGs) and polyvinyl alcohol (PVAs) are two polymers that have increased their presence in the composition of PCPs in recent years, but little is known about the effect of their accumulation in the environment on non-target species. Through embryotoxicity tests on two common models of aquatic organisms (Danio rerio and Xenopus laevis), this work aims to increase the knowledge of PEGs and PVAs' effects on non-target species. Animals were exposed to the pollutant for 96 h. The main embryotoxicity endpoint (mortality, hatching, malformations, heartbeat rate) was recorded every 24 h. The most significant results were hatching delay in Danio rerio exposed to both chemicals, in malformations (oedema, body malformations, changes in pigmentation and deformations of spine and tail) in D. rerio and X. laevis and significant change in the heartbeat rate (decrease or increase in the rate) in both animals for all chemicals tested.

Microfluidic Strategies for Encapsulation, Protection, and Controlled Delivery of Probiotics

Probiotics are indispensable for maintaining the structure of gut microbiota and promoting human health, yet their survivability is frequently compromised by environmental stressors such as temperature fluctuations, pH variations, and mechanical agitation. In response to these challenges, microfluidic technology emerges as a promising avenue. This comprehensive review delves into the utilization of microfluidic technology for the encapsulation and delivery of probiotics within the gastrointestinal tract, with a focus on mitigating obstacles associated with probiotic viability. Initially, it elucidates the design and application of microfluidic devices, providing a precise platform for probiotic encapsulation. Moreover, it scrutinizes the utilization of carriers fabricated through microfluidic devices, including emulsions, microspheres, gels, and nanofibers, with the intent of bolstering probiotic stability. Subsequently, the review assesses the efficacy of encapsulation methodologies through in vitro gastrointestinal simulations and in vivo experimentation, underscoring the potential of microfluidic technology in amplifying probiotic delivery efficiency and health outcomes. In sum, microfluidic technology represents a pioneering approach to probiotic stabilization, offering avenues to cater to consumer preferences for a diverse array of functional food options.

Temperature effects and molecular insights towards the optimization of polyvinyl alcohol as adsorbent of organic pollutants from aqueous solution

One of the easier methods of wastewater treatment is adsorption due to its simplicity in implementation, environmental friendliness, and economic feasibility. Polyvinyl alcohol (PVA) looks promising as an adsorbent due to its biocompatible, non-toxic, water-soluble and eco-friendly nature. The investigation of PVA for its potential in the adsorption of pollutants has been reported in many studies but the mechanistic understanding of the adsorption is poor. The present study used a theoretical approach through density functional theory and Monte Carlo with molecular dynamics simulations to investigate the adsorption mechanism behaviors of model organic molecules (bromothymol blue (BTB), methylene blue (MB), metronidazole (MNZ) and tetracycline (TC)) on PVA surface. The quantum chemical calculations result showed that with the increase in PVA chains (2, 4, 8, 16, and 32 units), the zero-point energy decreases (from -308.79 to -4922.93 kcal/mol) while the dipole moment increases (from 4.37 to 87.52 Debye). Temperature effect on the PVA chain structures showed the same trends for all the chain units and with the increase in temperature (50-600 K), there are no appreciable changes in zero-point energy, enthalpy energy increases while Gibbs free energy decreases. Considering PVA-pollutant complexes, the effects of temperature on the structures showed that there are no appreciable changes in the zero-point energy, Gibbs free and thermal energies increase with an increase in temperature while the kinetic rate of reactions decreases with an increase in temperature. The enthalpy of the reaction showed different trends with antibiotic and dye complexes. In all the thermodynamic properties investigated and the rate of reaction, the order of affinity of the pollutants with PVA followed TC > MNZ > MB > BTB. Monte Carlo simulation was used to investigate the adsorption behavior of the pollutants on the surface of PVA. The negative adsorption energies (-366.56 to -2266.81 kcal/mol) in terms of affinity towards the pollutants on the surface of PVA followed the sequence TC > MNZ > BTB > MB and the molecular dynamic simulation results followed the same order. The obtained results give valuable insights into the mechanism and performance of PVA as an adsorbent. Most of these computational observations are in good agreement with the available experimental results.

Core-shell nanofibers based on microalgae proteins/alginate complexes for enhancing survivability of probiotics

In this study, a novel one-step coaxial electrospinning process is employed to fabricate shell-core structure fibers choosing Chlorella pyrenoidosa proteins (CP) as the core material. These nanofibers, serving as the wall material for probiotic encapsulation, aimed to enhance the stability and antioxidant activity of probiotics in food processing, storage, and gastrointestinal environments under sensitive conditions. Morphological analysis was used to explore the beads-on-a-string morphology and core-shell structure of the electrospun fibers. Probiotics were successfully encapsulated within the fibers (7.97 log CFU/g), exhibiting a well-oriented structure along the distributed fibers. Compared to free probiotics and uniaxial fibers loaded with probiotics, encapsulation within microalgae proteins/alginate core-shell structure nanofibers significantly enhanced the probiotic cells' tolerance to simulated gastrointestinal conditions (p < 0.05). Thermal analysis indicated that microalgae proteins/alginate core-shell structure nanofibers displayed superior thermal stability compared to uniaxial fibers. The introduction of CP resulted in a 50 % increase in the antioxidant capacity of probiotics-loaded microalgae proteins/alginate nanofibers compared to uniaxial alginate nanofibers, with minimal loss of viability (0.8 log CFU/g) after 28 days of storage at 4 °C. In summary, this dual-layer carrier holds immense potential in probiotic encapsulation and enhancing their resistance to harsh conditions.

Preparation and Application of Hemostatic Hydrogels

Hemorrhage remains a critical challenge in various medical settings, necessitating the development of advanced hemostatic materials. Hemostatic hydrogels have emerged as promising solutions to address uncontrolled bleeding due to their unique properties, including biocompatibility, tunable physical characteristics, and exceptional hemostatic capabilities. In this review, a comprehensive overview of the preparation and biomedical applications of hemostatic hydrogels is provided. Particularly, hemostatic hydrogels with various materials and forms are introduced. Additionally, the applications of hemostatic hydrogels in trauma management, surgical procedures, wound care, etc. are summarized. Finally, the limitations and future prospects of hemostatic hydrogels are discussed and evaluated. This review aims to highlight the biomedical applications of hydrogels in hemorrhage management and offer insights into the development of clinically relevant hemostatic materials.

A Review of Advanced Abdominal Wall Hernia Patch Materials

Tension-free abdominal wall hernia patch materials (AWHPMs) play an important role in the repair of abdominal wall defects (AWDs), which have a recurrence rate of <1%. Nevertheless, there are still significant challenges in the development of tailored, biomimetic, and extracellular matrix (ECM)-like AWHPMs that satisfy the clinical demands of abdominal wall repair (AWR) while effectively handling post-operative complications associated with abdominal hernias, such as intra-abdominal visceral adhesion and abnormal healing. This extensive review presents a comprehensive guide to the high-end fabrication and the precise selection of these advanced AWHPMs. The review begins by briefly introducing the structures, sources, and properties of AWHPMs, and critically evaluates the advantages and disadvantages of different types of AWHPMs for AWR applications. The review subsequently summarizes and elaborates upon state-of-the-art AWHPM fabrication methods and their key characteristics (e.g., mechanical, physicochemical, and biological properties in vitro/vivo). This review uses compelling examples to demonstrate that advanced AWHPMs with multiple functionalities (e.g., anti-deformation, anti-inflammation, anti-adhesion, pro-healing properties, etc.) can meet the fundamental clinical demands required to successfully repair AWDs. In particular, there have been several developments in the enhancement of biomimetic AWHPMs with multiple properties, and additional breakthroughs are expected in the near future.

Cryostructuring of Polymeric Systems: 67 Properties and Microstructure of Poly(Vinyl Alcohol) Cryogels Formed in the Presence of Phenol or Bis-Phenols Introduced into the Aqueous Polymeric Solutions Prior to Their Freeze-Thaw Processing

Poly(vinyl alcohol) (PVA) physical cryogels that contained the additives of o-, m-, and p-bis-phenols or phenol were prepared, and their physico-chemical characteristics and macroporous morphology and the solute release dynamics were evaluated. These phenolic additives caused changes in the viscosity of initial PVA solutions before their freeze-thaw processing and facilitated the growth in the rigidity of the resultant cryogels, while their heat endurance decreased. The magnitude of the effects depended on the interposition of phenolic hydroxyls in the molecules of the used additives and was stipulated by their H-bonding with PVA OH-groups. Subsequent rinsing of such "primary" cryogels with pure water led to the lowering of their rigidity. The average size of macropores inside these heterophase gels also depended on the additive type. It was found also that the release of phenolic substances from the additive-containing cryogels occurred via virtually a free diffusion mechanism; therefore, drug delivery systems such as PVA cryogels loaded with either pyrocatechol, resorcinol, hydroquinone, or phenol, upon the in vitro agar diffusion tests, exhibited antibacterial activity typical of these phenols. The promising biomedical potential of the studied nanocomposite gel materials is supposed.

Novel PVA-Hyaluronan-Siloxane Hybrid Nanofiber Mats for Bone Tissue Engineering

Hyaluronan (HA) is a natural biodegradable biopolymer; its biological functions include cell adhesion, cell proliferation, and differentiation as well as decreasing inflammation, angiogenesis, and regeneration of damaged tissue. This makes it a suitable candidate for fabricating nanomaterials with potential use in tissue engineering. However, HA nanofiber production is restricted due to the high viscosity, low evaporation rate, and high surface tension of HA solutions. Here, hybrids in the form of continuous and randomly aligned polyvinyl alcohol (PVA)-(HA)-siloxane nanofibers were obtained using an electrospinning process. PVA-HA fibers were crosslinked by a 3D siloxane organic-inorganic matrix via sol-gel that restricts natural hydrophilicity and stiffens the structure. The hybrid nanofiber mats were characterized by FT-IR, micro-Raman spectroscopy, SEM, and biological properties. The PVA/HA ratio influenced the morphology of the hybrid nanofibers. Nanofibers with high PVA content (10PVA-8 and 10PVA-10) form mats with few beaded nanofibers, while those with high HA content (5PVA-8 and 5PVA-10) exhibit mats with mound patterns formed by "ribbon-like" nanofibers. The hybrid nanofibers were used as mats to support osteoblast growth, and they showed outstanding biological properties supporting cell adhesion, cell proliferation, and cell differentiation. Importantly, the 5PVA-8 mats show 3D spherical osteoblast morphology; this suggests the formation of tissue growth. These novel HA-based nanomaterials represent a relevant advance in designing nanofibers with unique properties for potential tissue regeneration.

Multifunctional nanogel based on carboxymethyl cellulose interfering with cellular redox homeostasis enhances phycocyanobilin photodynamic therapy

The redox homeostasis defense mechanism of tumor cells is one of the prime reasons for the unsatisfactory effect of photodynamic therapy (PDT). So far, little attention has been paid to this obstacle. In this work, we reported a synthesizing simple yet versatile nanogel (BCPS), synthesized by cystamine dihydrochloride functionalized sodium carboxymethylcellulose (CMC-SS), bovine serum albumin, and Phycocyanobilin self-assembly. The BCPS reduced the levels of glutathione molecules by reacting with glutathione, thereby interfering with intracellular redox homeostasis and enhancing the sensitivity of tumor cells to PDT. The BCPS was shown to possess excellent serum stability, high blood compatibility, low toxic side effects, and higher reactive oxygen species (ROS) utilization. After irradiation, the BCPS could significantly increase intracellular ROS level by approximately 1.6-fold and decrease the IC50 to HeLa cells by approximately 1.5-fold, compared to the pre-functional drugs BCP. This proposed strategy, based on increasing the utilization rate of ROS in tumor cells is promising for application potentials in tumor therapy.

Tri-modified ferric alginate gel with high regenerative properties catalysts for efficient degradation of rhodamine B

Water pollution caused by dyes has become a focal point of attention. Among them, the heterogeneous Fenton reaction has emerged as an effective solution to this problem. In this study, we designed a ferric alginate gel (PAGM) tri-modified with poly(vinyl alcohol), graphene oxide, and MoS2 as a heterogeneous Fenton catalyst for organic dye degradation. PAGM addresses the drawbacks of alginate gel, such as poor mechanical properties and gel chain dissolution, thereby significantly extending the catalyst's lifespan. The removal rate of rhodamine B by PAGM reached 95.5 % within 15 min, which was 5.9 times higher than that of unmodified ferric alginate gel. Furthermore, due to the π-π interactions, PAGM exhibits unique adsorption properties for pollutants containing benzene rings. Additionally, PAGM can be regenerated multiple times through a simple soaking procedure without any performance degradation. Finally, the reaction column constructed with PAGM maintained an 83.5 % removal rate even after 319 h of continuous wastewater treatment. This work introduces a novel concept for the study of alginate-based gel catalysts in heterogeneous Fenton reactions.

Solubilization of Fully Hydrolyzed Poly(vinyl alcohol) at Room Temperature for Fabricating Recyclable Hydrogels

The versatility of poly(vinyl alcohol) (PVA) makes it extensively utilized across various industries, while the solubilization of PVA in aqueous media is essential for its applications. However, the high crystallinity of the fully hydrolyzed PVA poses a big challenge in terms of its dissolution in aqueous media at room temperature. In this work, we present a straightforward, efficient, and safe strategy to achieve this objective by the integration of inorganic additives. The crucial aspect of additives lies in the interference of hydrogen bonds and breaking of the crystal domain within PVA chains, therefore greatly enhancing the solubility. At the optimal condition, the solubility of PVA can reach up to 45 wt% at 25 °C in 4 M HBr solution. It is further proven that the solubility of PVA follows the Hofmeister series well, where the chaotropes facilitate the solubilization process. In addition, the solubility is also significantly determined by the PVA type and additive concentration. By harnessing this feature, we successfully engineer recyclable PVA hydrogels with programmable mechanical properties. The hydrogels exhibit remarkable recyclability by affording a minimum of 8 regeneration cycles without experiencing significant deterioration in mechanical properties. Collectively, this research may significantly contribute to the advancement of PVA applications.

Plant-based Biomass/Polyvinyl Alcohol Gels for Flexible Sensors

Flexible sensors show great application potential in wearable electronics, human-computer interaction, medical health, bionic electronic skin and other fields. Compared with rigid sensors, hydrogel-based devices are more flexible and biocompatible and can easily fit the skin or be implanted into the body, making them more advantageous in the field of flexible electronics. In all designs, polyvinyl alcohol (PVA) series hydrogels exhibit high mechanical strength, excellent sensitivity and fatigue resistance, which make them promising candidates for flexible electronic sensing devices. This paper has reviewed the latest progress of PVA/plant-based biomass hydrogels in the construction of flexible sensor applications. We first briefly introduced representative plant biomass materials, including sodium alginate, phytic acid, starch, cellulose and lignin, and summarized their unique physical and chemical properties. After that, the design principles and performance indicators of hydrogel sensors are highlighted, and representative examples of PVA/plant-based biomass hydrogel applications in wearable electronics are illustrated. Finally, the future research is briefly prospected. We hope it can promote the research of novel green flexible sensors based on PVA/biomass hydrogel.

Diversity of Bioinspired Hydrogels: From Structure to Applications

Hydrogels are three-dimensional networks with a variety of structures and functions that have a remarkable ability to absorb huge amounts of water or biological fluids. They can incorporate active compounds and release them in a controlled manner. Hydrogels can also be designed to be sensitive to external stimuli: temperature, pH, ionic strength, electrical or magnetic stimuli, specific molecules, etc. Alternative methods for the development of various hydrogels have been outlined in the literature over time. Some hydrogels are toxic and therefore are avoided when obtaining biomaterials, pharmaceuticals, or therapeutic products. Nature is a permanent source of inspiration for new structures and new functionalities of more and more competitive materials. Natural compounds present a series of physico-chemical and biological characteristics suitable for biomaterials, such as biocompatibility, antimicrobial properties, biodegradability, and nontoxicity. Thus, they can generate microenvironments comparable to the intracellular or extracellular matrices in the human body. This paper discusses the main advantages of the presence of biomolecules (polysaccharides, proteins, and polypeptides) in hydrogels. Structural aspects induced by natural compounds and their specific properties are emphasized. The most suitable applications will be highlighted, including drug delivery, self-healing materials for regenerative medicine, cell culture, wound dressings, 3D bioprinting, foods, etc.

Hepar-on-a-sensor-platform with hybridization chain reaction amplification strategy to intuitively monitor the hepatoxicity of natural compounds

The irrational use of natural compounds in the treatment of diseases can lead to serious side effects, especially hepatoxicity, and its toxic effects are usually cumulative and imperceptible. Therefore, an accurate sensing platform is urgently needed to monitor the hepatotoxicity of natural compounds. Here, we deposited a thermo-responsive alginate-RGD/Pluronic hydrogel to construct an in vitro three-dimensional(3D) hepar-platform, and a thorough validation was adopted to evaluate the bioprinted hepatic constructs. The engineered hepar-platform was then employed to access its biological response toward Emodin (EM) and Triptolide (TP), two typical hepatotoxic natural compounds. Subsequently, we integrated it with a robust fluorescent sensor based on hybridization chain reaction amplification strategy (HCR) to monitor the early hepatotoxic biomarker - glutathione-S-transferase-alpha (GST-α) secreted by this 3D constructs. Our study was the first attempt to construct an accurate hepar-on-a-sensor platform that could effectively detect GST-α for monitoring the hepatoxic effects of natural compounds. The limit of detection of the platform was 0.3 ng ml^-1 and the accuracy of this platform was verified by enzyme linked immunosorbent assay. Furthermore, the variation of GST-α induced by EM and TP was consistent with hepatotoxicity studies, thus providing an important application value for evaluating the hepatotoxicity of natural compounds. STATEMENT OF SIGNIFICANCE: 1. We deposited a thermo-responsive alginate-RGD/Pluronic hydrogel to construct an in vitro three-dimensional(3D) hepar-platform, and elucidated the essential reasons why hybrid bioinks more suitable for 3D extrusion from biomaterials itself. Also, a thorough validation associated with a series of important proteins and genes involved in liver cell metabolism was adopted to evaluate the bioprinted hepatic constructs accurately 2. Glutathione-S-transferase-alpha is a soluble trace biomarker for acute hepatotoxic injury, the hepatotoxic effects of natural compounds on the secretion of GST-α has not been reported to date. We integrated our 3D hepar-platform with recognition molecules-aptamers and HCR amplification strategy to monitor the variation of GST-α, aiming at developing a robust and stable fluorescent biosensing platform to monitor the hepatoxicity of natural compounds.

An ion-coordination hydrogel based sensor array for point-of-care identification and removal of multiple tetracyclines

Misuse and overuse of tetracycline antibiotics (TCs) brings serious issues to ecological environment, food safety and human health. It is urgent to develop unique platform for high efficient identification and removal of TCs. In the present investigation, an effective and simple fluorescence sensor array was constructed based on the interaction between metal ions (Eu³⁺ and Al³⁺) and antibiotics. Benefiting from the different affinities between the ions and TCs, the sensor array can identify TCs from other antibiotics, which also can further differentiating four kinds of TCs (OTC, CTC, TC and DOX) from each other via linear discriminant analysis (LDA) technique. Meanwhile, the sensor array performed well in quantitative analysis of single TC antibiotic and differentiation of TCs mixtures. More interestingly, Eu³⁺ and Al³⁺-doped sodium alginate/polyvinyl alcohol hydrogel beads (SA/Eu/PVA and SA/Al/PVA) were further constructed, which can not only identify the TCs but simultaneously remove the antibiotics with high efficiency. The investigation provided an instructive way for rapid detection and environment protection.

Evaluating effect of salt leaching method on release and swelling rate of metformin nanoparticles loaded-chitosan/polyvinyl alcohol porous composite

In this study, salt leaching (SL) technique was used to prepare a chitosan/polyvinyl alcohol (CS/PVA) polymeric composite in order to load metformin nanoparticles (METNPs). Sodium chloride was added to the CS/PVA (0.5:0.1) composite to create a porous hydrogel using the SL technique. METNPs were then prepared by water/oil (w/o) method and loaded into the hydrogel structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed that >80 % of the METNPs were in the range of 10 nm. As a result, encapsulation increased due to the increase in surface-to-volume ratio. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) results confirmed that creating porosity in the polymer composition by the SL method led to increased CS/PVA polymer chain mobility. The drug encapsulation increased due to more porosity, and the release in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was according to the controlled diffusion kinetics. Furthermore, the drug release from CS/PVA composite was anomalous carrier type that could be attributed to the addition of salt. However, due to the increase the amount of PVA and the creation of a monotonous composite structure, encapsulation of drug decreased, which is in accordance with the polymer relaxation mechanism.

Cryostructuring of Polymeric Systems: 64. Preparation and Properties of Poly(vinyl alcohol)-Based Cryogels Loaded with Antimicrobial Drugs and Assessment of the Potential of Such Gel Materials to Perform as Gel Implants for the Treatment of Infected Wounds

Physical macroporous poly(vinyl alcohol)-based cryogels formed by the freeze-thaw technique without the use of any foreign cross-linkers are of significant interests for biomedical applications. In the present study, such gel materials loaded with the antimicrobial substances were prepared and their physicochemical properties were evaluated followed by an assessment of their potential to serve as drug carriers that can be used as implants for the treatment of infected wounds. The antibiotic Ceftriaxone and the antimycotic Fluconazole were used as antimicrobial agents. It was shown that the Ceftriaxone additives caused the up-swelling effects with respect to the cryogel matrix and some decrease in its heat endurance but did not result in a substantial change in the gel strength. With that, the drug release from the cryogel vehicle occurred without any diffusion restrictions, which was demonstrated by both the spectrophotometric recording and the microbiological agar diffusion technique. In turn, the in vivo biotesting of such drug-loaded cryogels also showed that these materials were able to function as rather efficient antimicrobial implants injected in the artificially infected model wounds of laboratory rabbits. These results confirmed the promising biomedical potential of similar implants.

Physicochemical Characteristics and Antibacterial Activities of Freeze-Thawed Polyvinyl Alcohol/Andrographolide Hydrogels

Andrographolide (AG) is one of the compounds in Andrographis paniculata, which has a high antibacterial activity. This paper reports the freeze-thaw method's use to synthesize polyvinyl alcohol (PVA) hydrogels loaded with AG and its characterization. From the morphological examination, the porosity of the PVA/AG hydrogel was found to increase with the increasing AG concentration. The swelling degree test revealed that the hydrogels' maximum swelling degrees were generally greater than 100%. The composite hydrogel with the highest fraction of andrographolide (PAG-4) showed greater weight loss than the hydrogel without AG (PAG-0). The molecular interaction between PVA and AG resulted in the narrowing of the band attributed to the O-H and C=O stretching bonds and the emergence of an amorphous domain in the composite hydrogels. The loading of AG disrupted the formation of hydroxyl groups in PVA and interrupted the cross-linking between PVA chains, which lead to the decrease of the compression strength and the crystallinity increased with increasing AG. The antibacterial activity of the composite hydrogel increased with increasing AG. The PAG-4 hydrogel had the highest antibacterial activity of 37.9 ± 4.6^b %. Therefore, the PVA/AG hydrogel has the potential to be used as an antibacterial device.

Production of 3D Printed Bi-Layer and Tri-Layer Sandwich Scaffolds with Polycaprolactone and Poly (vinyl alcohol)-Metformin towards Diabetic Wound Healing

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by impaired insulin secretion, sensitivity, and hyperglycemia. Diabetic wounds are one of the significant complications of T2DM owing to its difficulty in normal healing, resulting in chronic wounds. In the present work, PCL/PVA, PCL/PVA/PCL, and metformin-loaded, PCL/PVA-Met and PCL/PVA-Met/PCL hybrid scaffolds with different designs were fabricated using 3D printing. The porosity and morphological analysis of 3D-printed scaffolds were performed using scanning electron microscopy (SEM). The scaffolds' average pore sizes were between 63.6 ± 4.0 and 112.9 ± 3.0 μm. Molecular and chemical interactions between polymers and the drug were investigated with Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Mechanical, thermal, and degradation analysis of the scaffolds were undertaken to investigate the physico-chemical characteristics of the scaffolds. Owing to the structure, PCL/PVA/PCL sandwich scaffolds had lower degradation rates than the bi-layer scaffolds. The drug release of the metformin-loaded scaffolds was evaluated with UV spectrometry, and the biocompatibility of the scaffolds on fibroblast cells was determined by cell culture analysis. The drug release in the PCL/PVA-Met scaffold was sustained till six days, whereas in the PCL/PVA-Met/PCL, it continued for 31 days. In the study of drug release kinetics, PCL/PVA-Met and PCL/PVA-Met/PCL scaffolds showed the highest correlation coefficients (R²) values for the first-order release model at 0.8735 and 0.889, respectively. Since the layered structures in the literature are mainly obtained with the electrospun fiber structures, these biocompatible sandwich scaffolds, produced for the first time with 3D-printing technology, may offer an alternative to existing drug delivery systems and may be a promising candidate for enhancing diabetic wound healing.

Flexible Composites with Variable Conductivity and Memory of Deformation Obtained by Polymerization of Polyaniline in PVA Hydrogel

Flexible materials that provide an electric, magnetic, or optic response upon deformation or tactile pressure could be important for the development of smart monitors, intelligent textiles, or in the development of robotic skins. In this work we demonstrate the capabilities of a flexible and electrically conductive polymer material that produces an electrical response with any deformation, namely the electrical resistance of the material changes proportionally with the deformation pressure. Furthermore, the material exhibits a memory effect. When compressed beyond the elastic regime, it retains the memory of the plastic deformation by increasing its resistance. The material was obtained by in situ polymerization of semiconducting polyaniline (PANi) in a polyvinyl alcohol/glycerol (PVA/Gly) hydrogel matrix at −17 °C. Upon drying of the hydrogel, an elastomer composite is obtained, with rubber-like characteristics. When compressed/decompressed, the electrical resistance of the material exhibits an unusually long equilibration/relaxation time, proportional with the load applied. These phenomena indicate a complex relaxation and reconfiguration process of the PANi/PVA elastomer matrix, with the shape change of the material due to mechanical stress.

Development of antioxidant active packaging films with slow release properties incorporated with tea polyphenols-loaded porous starch microcapsules

Slow release active packaging films can realize the sustained release of active agents and prolong the shelf life of food. For this aim, a novel slow release active polyvinyl alcohol (PVA) film was developed by using solution casting method. With porous starch loaded with tea polyphenols (PSTP) as core material and maltodextrin (MD) as wall material, PSTP@MD microcapsules were prepared using freeze drying method and used as slow release carrier of tea polyphenols (TP) in the active films. The interactions between PSTP@MD microcapsules and PVA molecular chains were physical interactions. In addition, the relative crystallinity of the slow release active films was reduced to 23.74 %. The addition of PSTP@MD microcapsules can enhance the ductility of active films and reduce the water content and swelling degree of active films by 46.74 % and 54.38 %, respectively. Moreover, the thermal stability, water vapor and ultraviolet barrier properties of active films were promoted. The transparency and antioxidant activity of active films was high, and the radical scavenging activity of active films was 58 %. The encapsulation of TP with PSTP@MD microcapsules can realize the slow release of TP. The slow release active films had antioxidant activity and sustained release properties, which could be used as an active packaging film to extend the shelf life of food.

Hydroxyapatite Reinforced Polyvinyl Alcohol/Polyvinyl Pyrrolidone Based Hydrogel for Cartilage Replacement

Polyvinyl alcohol (PVA) and Polyvinyl Pyrrolidone (PVP) hydrogels are desirable biomaterials for soft tissue repair and replacement. However, the bio-inertness and poor cell adhesive potency of the PVA and PVP hinder the wide range of biomedical applications. In the present work, PVA and PVP were blended with a one-dimensional hydroxyapatite nanorod (HNr), and PVA/PVP/HNr composite hydrogel was synthesized by the freeze-thaw process. The developed hydrogels were characterized by Scanning Electron Microscope (SEM). The bio-ceramic nanohydroxyapatite content was optimized, and it was found that reinforcement improves mechanical strength as well as bioactivity. The compression strength values are 2.47 ± 0.73 MPa for the composite having 2 wt% of nanohydroxyapatite. The storage modulus was much higher than the loss modulus, which signifies the elastic dominancy similar to cartilage. Besides, the antimicrobial activity of nanohydroxyapatite reinforced PVA hydrogel towards bacterial species, Escherichia coli (E. Coli), Staphylococcus aureus (S. aureus) was satisfactory, and the in vitro biocompatibility response towards Human Mesenchymal stem cells(hMSC) after 72 h of culture confirms nanohydroxyapatite reinforced PVA/PVP hydrogels are the promising alternatives for next-generation cartilage substitutes.

Using polyvinyl alcohol-ionic hydrogels containing a wound healing agent to manage wounds in different environments

OBJECTIVE

To explore the effects of pH on properties of polyvinyl alcohol (PVA)-ionic hydrogels containing wound healing promoters.

METHOD

PVA was combined with a natural wound healing promoter (silk sericin (SS)), and an anionic agent (eosin (ES)) or cationic agent (methylene blue (MB)), and made into hydrogels. Properties of the hydrogels and behaviour at different pHs were investigated.

RESULTS

The density and gel fraction of PVA/SS-ES hydrogel and PVA/SS-MB hydrogel were considerably lower compared with hydrogel without SS. The swelling ratio and degradation of the hydrogels increased with increasing SS concentration in all pH solutions. The influence of SS in interrupting long-chain PVA molecules was confirmed based on changes in Fourier-transform infrared spectroscopy (FTIR). The SS released from the gels was found to interact with the ionic agent and influenced the release profile of the ionic agent. Surprisingly, the anionic agent in PVA/SS-ES hydrogel showed 70% release in high pH solution whereas the cationic agent in PVA/SS-MB hydrogel showed 86% release in low pH solution. Moreover, the active agent could accumulate on the skin layer and had a positive effect on a specific wound area.

CONCLUSION

Based on the results obtained in this study, it is suggested to use anionic hydrogels containing wound healing promoter for wounds at high pH and cationic hydrogels containing wound healing promoter for wounds with low pH. Ability to improve wound healing using a natural healing agent combined with ionic agents and controlling the pH of hydrogels will help in developing quick and low-cost treatment for wounds.

Vascular Repair by Grafting Based on Magnetic Nanoparticles

Magnetic nanoparticles (MNPs) have attracted much attention in the past few decades because of their unique magnetic responsiveness. Especially in the diagnosis and treatment of diseases, they are mostly involved in non-invasive ways and have achieved good results. The magnetic responsiveness of MNPs is strictly controlled by the size, crystallinity, uniformity, and surface properties of the synthesized particles. In this review, we summarized the classification of MNPs and their application in vascular repair. MNPs mainly use their unique magnetic properties to participate in vascular repair, including magnetic stimulation, magnetic drive, magnetic resonance imaging, magnetic hyperthermia, magnetic assembly scaffolds, and magnetic targeted drug delivery, which can significantly affect scaffold performance, cell behavior, factor secretion, drug release, etc. Although there are still challenges in the large-scale clinical application of MNPs, its good non-invasive way to participate in vascular repair and the establishment of a continuous detection process is still the future development direction.

Preparation of an Intelligent pH Film Based on Biodegradable Polymers for Monitoring the Food Quality and Reducing the Microbial Contaminants

Hydrogel refers to a three-dimensional cross-linked polymeric network made of synthetic or natural polymers that can hold water in its porous structure. The inclusion of hydrophilic groups in the polymer chains, such as amino, carboxyl, and hydroxyl groups, contributes to the hydrogel's water-holding ability. At physiological temperature and pH, these polymeric materials do not dissolve in water, but they do swell significantly in aqueous media. Hydrogel can be manufactured out of almost any water-soluble polymer, and it comes in a variety of chemical compositions and bulk physical properties. Hydrogel can also be made in a variety of ways. Hydrogel comes in a variety of physical shapes, including slabs, microparticles, nanoparticles, coatings, and films. Due to its ease of manufacture and self-application in clinical and fundamental applications, hydrogel has been widely exploited as a drug carrier. Contact lenses, artificial corneas, wound dressing, suture coating, catheters, and electrode sensors are some of the biomedical applications of hydrogels. The pigment color changes were observed from colorless to pale pink followed by dark reddish-pink. Anthocyanin was produced in large quantities and tested using a UV-visible spectrophotometer. At 450-550 nm, the largest peak (absorbance) was detected, indicating the presence of anthocyanin. The FTIR analysis of this study shows the different stretches of bonds at different peaks: 2918.309 (-C-H alkane stretch), 2812.12 (-C-H aldehyde weak intensity), 192320.37/cm (C-O bend), 21915.50, 2029.08/cm (-C=C arene group), 1906.94/cm (=C-H aromatics), 1797.78/cm (=C-H), 1707.94 (-C=O ketene), 1579.70, 1382.96 (C-H alkane strong bend), 889.18/cm (C-H aromatics plane bend), and 412.77/cm (-C-CI strong bond). The spectra of the PVA/chitosan film depict the peak's formation: 1571.88, 1529.55, 1500.62/cm (C-H alkene strong bend), 1492.90, 1483.26, 1467.83/cm (C-H alkene strong bond), 670.48, 443.63, 412.77/cm (-O-H carboxylic acids with great intensity), 1708.93 (-C=O ketone), and 1656.0/cm (alkenyl C=C stretch strong bond).

Preparation and Characterization of Eco-Friendly Transparent Antibacterial Starch/Polyvinyl Alcohol Materials for Use as Wound-Dressing

In this study, eco-friendly and transparent starch-based/polyvinyl alcohol/citric acid composite films are evaluated for their efficacy as wound dressing materials. The starch/polyvinyl alcohol (PVA) materials with added citric acid (0.46-1.83 wt%) and glycerol were made and handled based on the modified casting method. This new formulation decreases the amount of PVA used in the conventional preparation method. Citric acid ensures an appropriate antibacterial environment for wound-dressing materials. The mechanical, chemical, and surface morphological properties of such films were assessed and analyzed by tensile strength tests, UV-Vis spectrometry, swelling index, and scanning electron microscopy (SEM). Furthermore, the water vapor transmission (WVT) quantity was measured for an ideal wound-healing process to investigate an optimal moisture environment around the wound bed. Moreover, the pH level of the dressings was measured to examine the possibility of bacterial growth around these starch-based films. Additionally, the films' in-vitro antibacterial activities were studied against the two most common Gram-positive and Gram-negative bacteria (Escherichia coli and Staphylococcus aureus). The new starch-based dressings demonstrated suitable degradation, antibacterial activity, fluid absorption, and adequate mechanical strength, representing wound-dressing materials' vital features.