Assessment of PVA/silver nanocomposite hydrogel patch as antimicrobial dressing scaffold: Synthesis, characterization and biological evaluation

Electrostatically assembled maghemite nanoparticles-Lactobacillus plantarum: A novel hybrid for enhanced antioxidant, antimicrobial, and antibiofilm efficacy

Excessive antibiotic use contributes to oxidative stress and microbial imbalance, leading to increased growth of pathogens and biofilm formation. To address this, we developed a novel electrostatically assembled hybrid of maghemite nanoparticles and Lactobacillus plantarum (MNPs-LAB) as a multifunctional agent. Structural and surface interactions were confirmed through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), while transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) analyses revealed a uniform distribution of MNPs on the LAB surface. The MNPs-LAB hybrid exhibited strong antioxidant activity (71.45 % at 500 µg/mL) and enhanced antimicrobial performance against Listeria monocytogenes. In addition, the hybrid inhibited biofilm formation and effectively eradicated preformed biofilms of Staphylococcus succinus, Listeria monocytogenes, Escherichia coli, and Salmonella thompson. Notably, the low cytotoxicity observed in Caco-2 cells indicated good biocompatibility with intestinal epithelial cells. These results highlight the potential of MNPs-LAB hybrid as a safe and effective therapeutic candidate for combating oxidative stress, microbial infections, and biofilm-associated challenges.

Leveraging metal oxide-fenugreek hydrogel nanocomposites for enhanced structural and biological properties

This study focuses on the green synthesis of metal oxide nanoparticles (MnO2, Fe2O3, and CuO). Fenugreek extract was used as a natural reducing and capping agent for this nanoparticle synthesis. Fenugreek hydrogel was also explored as a convenient, ready-made reaction template for the in situ reduction and formation of these nanoparticles. Standard characterization techniques revealed that the resulting nanocomposite hydrogels exhibited enhanced thermal and mechanical properties. These hydrogels also demonstrated superior antioxidant and antibacterial activities against Gram-negative (E. coli) and Gram-positive (B. subtilis) bacteria. Remarkably, the nanocomposite hydrogels resisted microbial infestation even after 21 days. This work highlights the potential for tailoring such ready-made nanocomposite hydrogel systems for advanced applications, including wound healing, drug delivery systems, and antimicrobial coatings.

Multifunctional Ag-Poly(N-isopropylacrylamide/itaconic Acid) Hydrogel Nanocomposites Prepared by Gamma Irradiation for Potential Application as Topical Treatment Dressings

Today, hydrogel dressings that can protect injury sites and effectively promote healing have become highly desirable in wound management. Therefore, multifunctional silver-poli(N-isopropylacrylamide/itaconic acid) (Ag-P(NiPAAm/IA)) hydrogel nanocomposites were developed for potential application as topical treatment dressings. The radiolytic method, used for the crosslinking of the polymer matrix as well as for the in situ incorporation of silver nanoparticles (AgNPs) into the polymer matrix, enables the preparation of hydrogel nanocomposites without introducing harmful and toxic agents. Moreover, materials produced using γ-irradiation are simultaneously sterilized, thus fulfilling one of the basic requirements regarding their potential biomedical applications. The NiPAAm/IA ratio and the presence of AgNPs influenced the microstructural parameters of the investigated systems. Increasing the IA content leads to the formation of a more porous polymer matrix with larger pores, while the incorporated AgNPs act as additional junction points, decreasing the porosity and pore size of the resulting nanocomposite hydrogels. Swelling studies showed that most investigated systems uptake the fluids from their surroundings by non-Fick diffusion. Further, the Ag+ ion release, antibacterial activity, and cytotoxicity of Ag-P(NiPAAm/IA) hydrogel nanocomposites were examined to evaluate their biomedical potential. All hydrogel nanocomposites showed an initial burst release of Ag+ ions (useful in preventing bacteria adherence and biofilm formation), followed by a slower release of the same (ensuring sterility for longer use). An antibacterial activity test against Escherichia coli and Staphylococcus aureus showed that Ag-P(NiPAAm/IA) hydrogel nanocomposites, with silver concentrations around 10 ± 1 ppm, successfully prevent bacterial growth. Finally, it was shown that the investigated hydrogel nanocomposites do not exhibit a cytotoxic effect on human keratinocyte HaCaT cells. Therefore, these multifunctional hydrogel nanocomposites may promote wound repair and show promising potential for application as functional wound dressing.

Antibacterial and antibiofilm activity of silver nanoparticles stabilized with C-phycocyanin against drug-resistant Pseudomonas aeruginosa and Staphylococcus aureus

Background

Biofilms are bacterial communities that can protect them against external factors, including antibiotics. In this study, silver nanoparticles (AgNPs) were formed by modifying AgNPs with C-phycocyanin (Ag-Pc) to inhibit the growth of carbapenem-resistant Pseudomonas aeruginosa (CR P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) and destroy biofilm of these bacteria.

Methods

The AgNPs were prepared with the green synthesis method, and Pc was used to stabilize the AgNPs. The Ag-Pc's antibacterial and antibiofilm effects were evaluated using the Microbroth dilution method and microtiter plate assay. The inhibitory effect of Ag-Pc on the expression of biofilm-related genes was evaluated by real-time PCR. Moreover, the MTT assay was used to assess the Ag-Pc toxicity.

Results

The Ag-Pc minimum inhibitory concentration (MIC) was 7.4 μg/mL for CR P. aeruginosa and MRSA. Pc did not show antibacterial effects against any of the strains. Ag-Pc suppressed biofilm formation and destroyed matured biofilm in both bacteria more efficiently than the AgNPs (P< 0.05). The expression of all genes was not significantly reduced in the presence of synthesized nanoparticles. Finally, the MTT assay results did not show toxicity against a murine fibroblast cell line (L929) at MIC concentration.

Conclusion

The present study showed the promising potential of Pc for improving the antibacterial and antibiofilm function of AgNPs and inhibiting drug-resistant bacteria. Therefore, Ag-Pc nanoparticles can be considered a promising therapeutic approach for the managing of the bacterial biofilm.

Metal organic framework-based polymeric hydrogel: A promising drug delivery vehicle for the treatment of breast cancer

The constraints associated with current cancer therapies have inspired scientists to develop advanced, precise, and safe drug delivery methods. These delivery systems boost treatment effectiveness, minimize harm to healthy cells, and combat cancer recurrence. To design advanced drug delivery vehicle with these character, in the present manuscript, we have designed a self-healing and injectable hybrid hydrogel through synergistically interacting metal organic framework, CuBTC with the poly(vinyl alcohol) (PVA). This hybrid hydrogel acts as a localized drug delivery system and was used to encapsulate and release the anticancer drug 5-Fluorouracil selectively at the targeted site in response to the physiological pH. The hydrogel was formed through transforming the gaussian coil like matrix of PVA-CuBTC into a three-dimensional network of hydrogel upon the addition of crosslinker; borax. The biocompatible character of the hydrogel was confirmed through cell viability test. The biocompatible hybrid hydrogel then was used to encapsulate and studied for the pH responsive release behavior of the anti-cancer drug, 5-FU. The in vitro cytotoxicity of the drug-loaded hydrogel was evaluated against MCF-7 and HeLa cells. The study confirms that the hybrid hydrogel is effective for targeted and sustained release of anticancer drugs at cancer sites.

Application of plasma-activated hydrogen peroxide solution synergized with Ag@SiO2 modified polyvinyl alcohol coating for strawberry preservation

To extend the postharvest storage time of strawberries, this study aims to prepare a composite coating using plasma-activated hydrogen peroxide solution (PAH) synergized with nano-Ag@SiO2 by blending method to modify polyvinyl alcohol (PVA) solution. Results showed that the viscosity and the swelling rate of PVA significantly decreased with the addition of Ag@SiO2 at 0.18 %. Meanwhile, the elongation at break and the tensile strength of PVA increased to 0.87 MPa and 214 %. When the addition of Ag@SiO2 was 0.18 % and the composite ratio of PAH to PVA was 1:1, the composites could inactivate the pathogenic bacteria at 2 h. During the storage of strawberries, the initial colony counts on the surface of strawberries could be reduced by about 1 lg CFU/g after coating with the composite film. Moreover, with the extension of the storage time to 7 d, the respiratory intensity, colony counts, and rot index in the strawberries were 65.7 mg/(kg•h), 4.05 log CFU/g, and 38.7 %. Meanwhile, the superoxide dismutase activity and Vc content were 944 U/g and 690 μg/g, respectively. Overall, this study provides ideas and the theoretical basis for applying composite films in fruit preservation.

Ibuprofen-Loaded Silver Nanoparticle-Doped PVA Gels: Green Synthesis, In Vitro Cytotoxicity, and Antibacterial Analyses

In contrast to conventional drug delivery systems, controlled drug release systems employ distinct methodologies. These systems facilitate the release of active substances in predetermined quantities and for specified durations. Polymer hydrogels have gained prominence in controlled drug delivery because of their unique swelling-shrinkage behavior and ability to regulate drug release. In this investigation, films with a hydrogel structure were crafted using polyvinyl alcohol, a biocompatible polymer, and silver nanoparticles. Following characterization, ibuprofen was loaded into the hydrogels to evaluate their drug release capacity. The particle sizes of silver nanoparticles synthesized using a green approach were determined. This study comprehensively examined the structural properties, morphological features, mechanical strength, and cumulative release patterns of the prepared films. In vitro cytotoxicity analysis was employed to assess the cell viability of drug-loaded hydrogel films, and their antibacterial effects were examined. The results indicated that hydrogel films containing 5% and 10% polyvinyl alcohol released 89% and 97% of the loaded drug, respectively, by day 14. The release kinetics fits the Korsmeyer-Peppas model. This study, which describes nanoparticle-enhanced polyvinyl alcohol hydrogel systems prepared through a cost-effective and environmentally friendly approach, is anticipated to contribute to the existing literature and serve as a foundational study for future research.

Enzyme-Mineralized PVASA Hydrogels with Combined Toughness and Strength for Bone Tissue Engineering

Enzymatic mineralization is an advanced mineralization method that is often used to enhance the stiffness and strength of hydrogels, but often accompanied by brittle behavior. Moreover, the hydrogel systems with dense networks currently used for enzymatic mineralization are not ideal materials for bone repair applications. To address these issues, two usual bone repair hydrogels, poly(vinyl alcohol) (PVA) and sodium alginate (SA), were selected to form a double-network structure through repeated freeze-thawing and ionic cross-linking, followed by enzyme mineralization. The results demonstrated that both enzymatic mineralization and double-network structure improved the mechanical and biological properties and even exhibited synergistic effects. The mineralized PVASA hydrogels exhibited superior comprehensive mechanical properties, with a Young's modulus of 1.03 MPa, a storage modulus of 103 kPa, and an equilibrium swelling ratio of 132%. In particular, the PVASA hydrogel did not suffer toughness loss after mineralization, with a high toughness value of 1.86 MJ/m3. The prepared hydrogels also exhibited superior biocompatibility with a cell spreading area about 13 times that of mineralized PVA. It also effectively promoted cellular osteogenic differentiation in vitro and further promoted the formation of new bone in the femur defect region in vivo. Overall, the enzyme-mineralized PVASA hydrogel demonstrated combined strength and toughness and great potential for bone tissue engineering applications.

Formulation and Comprehensive Evaluation of Biohybrid Hydrogel Membranes Containing Doxycycline or Silver Nanoparticles

Complicated wounds often require specialized medical treatments, and hydrogels have emerged as a popular choice for wound dressings in such cases due to their unique properties and the ability to incorporate and release therapeutic agents. Our focus was to develop and characterize a new optimized formula for biohybrid hydrogel membranes, which combine natural and synthetic polymers, bioactive natural compounds, like collagen and hyaluronic acid, and pharmacologically active substances (doxycycline or npAg). Dynamic (oscillatory) rheometry confirmed the strong gel-like properties of the obtained hydrogel membranes. Samples containing low-dose DOXY showed a swelling index of 285.68 ± 6.99%, a degradation rate of 71.6 ± 0.91% at 20 h, and achieved a cumulative drug release of approximately 90% at pH 7.4 and 80% at pH 8.3 within 12 h. The addition of npAg influenced the physical properties of the hydrogel membranes. Furthermore, the samples containing DOXY demonstrated exceptional antimicrobial efficacy against seven selected bacterial strains commonly associated with wound infections and complications. Biocompatibility assessments revealed that the samples exhibited over 80% cell viability. However, the addition of smaller-sized nanoparticles led to decreased cellular viability. The obtained biohybrid hydrogel membranes show favorable properties that render them suitable for application as wound dressings.

Thermal, morphology and bacterial analysis of pH-responsive sodium carboxyl methylcellulose/ fumaric acid/ acrylamide nanocomposite hydrogels: Synthesis and characterization

In this present investigation, sodium carboxymethyl cellulose grafted with Fumaric acid/Acrylamide (CMC/FA/AAm=CFA) hydrogel and their silver nanocomposite hydrogels (CFA-Ag x, x = 5, 10 and 20) were developed by simple, cost effective and ecofriendly greener method. Mint leaf extract was used as an efficient natural reducing agent due to presence of active and antioxidant potential of polyphenol and flavonoid components. Swelling equilibrium of CFA hydrogel showed Seq% 3000 both in pH medium and distilled water. CFA (90:10) hydrogel has been produced greater than Seq% 6000. The synthesized CFA (90:10)-Ag-5, CFA (90:10)-Ag-10 and CFA (90:10)-Ag-20 nanocomposite hydrogels have been observed lower Seq% 2000-3000 than the CFA hydrogel. The homogeneous distribution of AgNPs throughout the CFA hydrogel and nanocomposites has been explored by SEM analysis. The interaction of network heteroatoms with AgNPs has been strongly revealed by the FTIR spectra and XRD analysis. The thermal stability of CFA (90:10)-Ag-5, 10, and 20 nanocomposite hydrogels have showed greater stability than CFA hydrogel which is confirmed by TGA/DSC thermogram analysis. The TEM analysis was used to explore a uniform distribution of spherical AgNPs (10 nm-50 nm) embedded on the CFA composite hydrogel. The CFA (90:10)-Ag-20 nanocomposite hydrogel has showed good antibacterial activity beside E. coli (Gram positive) and S. aureus (Gram negative) pathogens. Based on the antibacterial activity and swelling properties of CFA-Ag nanocomposite hydrogels have the ability to accelerate the antibacterial activity and are potential candidates for medical and environmental applications.

Development of a Microfluidic Formatted Ultrasound-Controlled Monodisperse Lipid Vesicles' Hydrogel Dressing Combined with Ultrasound for Transdermal Drug Delivery System

Transdermal drug delivery system (TDDS) has attracted much attention in the pharmaceutical technology area. However, the current methods are difficult to ensure penetration efficiency, controllability, and safety in the dermis, so its widespread clinical use has been limited. This work proposes an ultrasound-controlled monodisperse lipid vesicles (U-CMLVs) hydrogel dressing, which combines with ultrasound to form TDDS. Using microfluidic technology, prepare size controllable U-CMLVs with high drug encapsulation efficiency and quantitative encapsulation of ultrasonic response materials, and even uniform mix them with hydrogel to prepare the required thickness of dressings. The high encapsulation efficiency can ensure sufficient dosage of the drugs and further realize the control of ultrasonic response through quantitative encapsulation of ultrasound-responsive materials. Using high frequency (5 MHz, 0.4 W cm-2 ) and low frequency (60 kHz, 1 W cm-2 ) ultrasound to control the movement and rupture of U-CMLVs, the contents not only penetrate the stratum corneum into the epidermis but also break through the bottleneck of penetration efficiency, and deep into the dermis. These findings provide the groundwork for deep, controllable, efficient, and safe drug delivery through TDDS and lay a foundation for further expanding its application.

Humidity-/Sweat-Sensitive Electronic Skin with Antibacterial, Antioxidation, and Ultraviolet-Proof Functions Constructed by a Cross-Linked Network

Most electronic skins (e-skins) show unique performance or possess sensory functions. The raw materials used for their preparation are potentially toxic or harmful, and there may be problems such as poor compatibility between the conductive fillers and polymers. In this paper, a silver-loaded nanocomposite film (PVA/CMS/vanillin/nanoAg) was prepared by the in situ reduction method in a greener route. The mechanical properties of this nanocomposite film had improved with a tensile strength of 30.95 MPa, an elongation at break of 101.9%, and a Young's modulus of 10.62 MPa. In the composite matrix, a cross-linked network was constructed based on the coordination and hydrogen bonds, which was conducive to the stability of the reduced AgNPs and AgNWs. When applied as an e-skin in humidity/sweat sensors and wearable electronics, the nanocomposite film responds to humidity within 60 s and records the electric signals of human joint movements and skin sweating with a response range of 0-140% to strain at 93% RH. This kind of e-skin has excellent antibacterial and antioxidant activities and shows an outstanding ultraviolet-proof performance, which provides a greener promising reference route for the design of wearable e-skins to monitor the health and movements of humans.

Biogenic Synthesis of Silver Nanoparticles Using Catharanthus roseus and Its Cytotoxicity Effect on Vero Cell Lines

Background: Type 2 diabetes mellitus (DM2) is a chronic and sometimes fatal condition which affects people all over the world. Nanotherapeutics have shown tremendous potential to combat chronic diseases—including DM2—as they enhance the overall impact of drugs on biological systems. Greenly synthesized silver nanoparticles (AgNPs) from Catharanthus roseus methanolic extract (C. AgNPs) were examined primarily for their cytotoxic and antidiabetic effects. Methods: Characterization of C. AgNPs was performed by UV−vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and atomic force microscopy (AFM). The C. AgNPs were trialed on Vero cell line and afterwards on an animal model (rats). Results: The C. AgNPs showed standard structural and functional characterization as revealed by FTIR and XRD analyses. The zetapotential analysis indicated stability while EDX analysis confirmed the formation of composite capping with Ag metal. The cytotoxic effect (IC50) of C. AgNPs on Vero cell lines was found to be 568 g/mL. The animal model analyses further revealed a significant difference in water intake, food intake, body weight, urine volume, and urine sugar of tested rats after treatment with aqueous extract of C. AgNPs. Moreover, five groups of rats including control and diabetic groups (NC1, PC2, DG1, DG2, and DG3) were investigated for their blood glucose and glycemic control analysis. Conclusions: The C. AgNPs exhibited positive potential on the Vero cell line as well as on experimental rats. The lipid profile in all the diabetic groups (DG1-3) were significantly increased compared with both of the control groups (p < 0.05). The present study revealed the significance of C. AgNPs in nanotherapeutics.

Investigation of biological effects of chitosan magnetic nano-composites hydrogel

The growing concern about microorganism infections, especially hospital-acquired infections, has driven the demand for effective and safe agents in recent years. Herein, novel nanocomposites were prepared based on layered double hydroxides (LDH NPs), Fe₂O₃nanoparticles (Fe₂O₃NPs), and chitosan hydrogel beads in different concentrations. The characteristics and composition of the prepared materials were investigated by various techniques such as XRD, FESEM, and FTIR. The results indicate that the nanocomposites are synthesized successfully, and each component is present in hydrogel matrixes. Then, their biomedical properties, including antibacterial, antifungal, and antioxidant activity, were examined. Our findings demonstrate that the antimicrobial activity of nanocomposites significantly depends on the concentration of each component and their chemical groups. It shows itself in the result of the inhibitory zone of all bacteria or fungi samples. The obtained results indicate that the nanocomposite of Chitosan-hydrogel beads with 20% LDH and Fe₂O₃(CHB-LDH-Fe₂O₃%20) and Chitosan-hydrogel beads based on 20% LDH (CHB-LDH%20) showed excellent antibacterial and antifungal properties against all tested bacteria and fungi (P ≤ 0.01). In addition, the antioxidant effects of the synthesized materials (especially CHB-LDH Fe₂O₃%20 and CHB-LDH%20) were investigated, showing high antioxidant efficacy against DPPH free radicals (P ≤ 0.01). According to our findings, we can say that these materials are promising biomaterials for inhibiting some infectious bacteria and fungi.

Application of Ag@SiO2 nanoparticles within PVA to reduce growth of E. coli and S. aureus in beef patties

To overcome defects of polyvinyl alcohol (PVA) and expand its applications in food preservation, PVA/Ag@SiO₂ nanocomposite films were prepared using the solution intercalation film-casting method. Transmission electron microscopy, X-ray diffraction, and UV-visible absorption spectra were applied to confirm the synthesis of the nanoparticles (NPs). Effects of Ag@SiO₂ NPs on physicochemical characteristics of films like viscosity, swelling ratio, tensile strength, elongation at break, as well as antibacterial activity were also evaluated. Results indicate that Ag@SiO₂ NPs could be synthesized successfully, and the increasing concentration of Ag@SiO₂ NPs led to the decrease in viscosity and the swelling ratio of the PVA/Ag@SiO₂ NPs nanocomposite films. PVA/Ag@SiO₂ nanocomposite films exhibited increased tensile strength and strong antibacterial activity against Escherichia coli and Staphylococcus aureus. The films had higher antibacterial activity toward E. coli compared with S. aureus. Beef patties were applied to verify the practicality of PVA/Ag@SiO₂ films. PVA/Ag@SiO₂ NPs nanocomposite films act as an active food packaging system showing great potential in retaining food safety and prolonging the shelf-life of packaged foods. PRACTICAL APPLICATION: During the storage of fresh meat, the microbial count on the meat surface increased with increasing storage time; meat proteins could be broken down by microorganisms, causing the tissue structure to be destroyed, leading to loose muscle fibers and loss of nutrient-containing juices. In this paper, by improving the PVA film, a new antibacterial membrane was prepared, which can be used for fresh meat sold in supermarkets, as a lining at the bottom of the meat or directly covering the meat. The method can significantly decrease the number of microorganisms and extend the shelf-life of fresh meat.

A Porous Hydrogel with High Mechanical Strength and Biocompatibility for Bone Tissue Engineering

Polyvinyl alcohol (PVA) hydrogels are considered to be ideal materials for tissue engineering due to their high water content, low frictional behavior, and good biocompatibility. However, their limited mechanical properties restrict them from being applied when repairing load-bearing tissue. Inspired by the composition of mussels, we fabricated polyvinyl alcohol/hydroxyapatite/tannic acid (PVA/HA/TA) hydrogels through a facile freeze–thawing method. The resulting composite hydrogels exhibited high moisture content, porous structures, and good mechanical properties. The compressive strength and tensile strength of PVA hydrogels were improved from 0.77 ± 0.11 MPa and 0.08 ± 0.01 MPa to approximately 3.69 ± 0.41 MPa and 0.43 ± 0.01 MPa, respectively, for the PVA/HA/1.5TA hydrogel. The toughness and the compressive elastic modulus of PVA/HA/1.5TA hydrogel also attained 0.86 ± 0.02 MJm⁻³ and 0.11 ± 0.02 MPa, which was approximately 11 times and 5 times higher than the PVA hydrogel, respectively. The PVA/HA/1.5TA hydrogel also exhibited fatigue resistance abilities. The mechanical properties of the composite hydrogels were improved through the introduction of TA. Furthermore, in vitro PVA/HA/1.5TA hydrogel showed excellent cytocompatibility by promoting cell proliferation in vitro. Scanning electron microscopy analysis indicated that PVA/HA/1.5TA hydrogels provided favorable circumstances for cell adhesion. The aforementioned results also indicate that the composite hydrogels had potential applications in bone tissue engineering, and this study provides a facile method to improve the mechanical properties of PVA hydrogel.

Influence of silver nanoparticles on the tissue reaction of polyacrylic acid-based gel

Purpose:

To study the influence of silver nanoparticles (AgNP) on tissue reaction when incorporated into a polymeric matrix of polyacrylic acid-based (Carbopol^®) gel as a proposal for a new low-cost type of biomaterial that is simple to manufacture for use as an antimicrobial and antioxidative dressing.

Methods:

In-vivo tests of implantation in the subcutaneous tissue of the back of rats were performed using polyethylene tubes in three situations: empty, only the gel, and gel incorporated with AgNP. Then, the tissue reaction was studied by counting inflammatory cells. Additionally, in-vitro tests of the antioxidative and antimicrobial activity of AgNP were performed. The radical 2,2 diphenyl-1 picrylhydrazyl (DPPH) was used to test the antioxidative activity of AgNP using electron spin resonance. The antimicrobial activity of AgNP was determined by minimum inhibitory concentration against the microorganisms: Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli.

Results:

The results indicated that AgNP presents antioxidative activity and was able to inhibit the growth of the microorganisms tested. The addition of AgNP in Carbopol^® did not alter the tissue inflammatory response (p>0.05, Kruskal-Wallis’s test).

Conclusions:

The new biomaterial is promising for future use as a dressing for its beneficial properties for regenerative processes.

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.

Engineering Biomimetic Extracellular Matrix with Silica Nanofibers: From 1D Material to 3D Network

Biomaterials at nanoscale is a fast-expanding research field with which extensive studies have been conducted on understanding the interactions between cells and their surrounding microenvironments as well as intracellular communications. Among many kinds of nanoscale biomaterials, mesoporous fibrous structures are especially attractive as a promising approach to mimic the natural extracellular matrix (ECM) for cell and tissue research. Silica is a well-studied biocompatible, natural inorganic material that can be synthesized as morpho-genetically active scaffolds by various methods. This review compares silica nanofibers (SNFs) to other ECM materials such as hydrogel, polymers, and decellularized natural ECM, summarizes fabrication techniques for SNFs, and discusses different strategies of constructing ECM using SNFs. In addition, the latest progress on SNFs synthesis and biomimetic ECM substrates fabrication is summarized and highlighted. Lastly, we look at the wide use of SNF-based ECM scaffolds in biological applications, including stem cell regulation, tissue engineering, drug release, and environmental applications.

Synthesis And Evaluation of Polyethylene Glycol-4000-Co-Poly (AMPS) Based Hydrogel Membranes for Controlled Release of Mupirocin for Efficient Wound Healing

BACKGROUND

Chronic wound healing is a major challenge for health care system around the globe. Current study was conducted to develop and characterize chemically cross-linked polyethylene glycol-co-poly (AMPS) hydrogel membranes to enhanced the wound healing efficiency of antibiotic mupirocin (MP).

METHODS

Free radical polymerization technique was used for the development of hydrogel membranes. In aqueous medium, polymer PEG-4000 cross-linked with the monomer 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in the presence of initiators ammonium peroxide sulfate (APS) and sodium hydrogen sulfite (SHS). N, N-Methylenebisacrylamide (MBA) was used as cross-linker in the preparation of hydrogel membranes. Developed membranes were spherical, transparent, and elastic. FTIR, TGA/DSC, and SEM were used to characterize the polymeric system. Swelling behavior, drug loading, and its release pattern at pH of 5.5 and 7.4, irritation study, ex vivo drug permeation, and deposition study was also evaluated.

RESULTS

Formed membranes were spherical, transparent and elastic. The formation of a stable polymeric network was confirmed by structural and thermal analysis. Permeation of the drug its deposition in the skin showed good permeation and retention. No irritancy to the skin was observed.

CONCLUSION

On the basis of results obtained, the present study concluded that it may be an ideal network for the delivery of mupirocin in skin infections.

A New Dermal Substitute Containing Polyvinyl Alcohol with Silver Nanoparticles and Collagen with Hyaluronic Acid: In Vitro and In Vivo Approaches

The experimental use of poly (alcohol-vinyl) (PVA) as a skin curative is increasing widely. However, the use of this hydrogel is challenging due to its favorable properties for microbiota growth. The association with silver nanoparticles (AgNPs) as an antimicrobial agent turns the match for PVA as a dressing, as it focuses on creating a physical barrier to avoid wound dehydration. When associated with extracellular components, such as the collagen matrix, the device obtained can create the desired biological conditions to act as a skin substitute. This study aimed to analyze the anti-microbiological activity and the in vitro and in vivo responses of a bilaminar device of PVA containing AgNPs associated with a membrane of collagen-hyaluronic acid (col-HA). Additionally, mesenchymal stem cells were cultured in the device to evaluate in vitro responses and in vivo immunomodulatory and healing behavior. The device morphology revealed a porous pattern that favored water retention and in vitro cell adhesion. Controlled wounds in the dorsal back of rat skins revealed a striking skin remodeling with new epidermis fulfilling all previously injured areas after 14 and 28 days. No infections or significant inflammations were observed, despite increased angiogenesis, and no fibrosis-markers were identified as compared to controls. Although few antibacterial activities were obtained, the addition of AgNPs prevented fungal growth. All results demonstrated that the combination of the components used here as a dermal device, chosen according to previous miscellany studies of low/mid-cost biomaterials, can promote skin protection avoiding infections and dehydration, minimize the typical wound inflammatory responses, and favor the cellular healing responses, features that give rise to further clinical trials of the device here developed.

Characterization of a novel semi-interpenetrating hydrogel network fabricated by polyethylene glycol diacrylate/polyvinyl alcohol/tragacanth gum as a wound dressing

In this research, a novel semi-interpenetrating hydrogel network comprised of polyethylene glycol diacrylate (PEGDA)/polyvinyl alcohol (PVA)/tragacanth gum (TG) with adaptable mechanical, biological, and physical characteristics was fabricated for wound healing purposes. The chemical structure of the films and the surface morphology were examined by FTIR and SEM, respectively. In addition, swelling ratio, mechanical characteristics, water vapor transmission rate (WVTR), gel fraction, and degradability of the hydrogels were assessed. To evaluate their cytocompatibility, MTT assay and cell attachment studies were performed. The FTIR results showed that the vinyl peaks were eliminated during crosslinking between PEGDA chains. The results also showed that incorporating PVA into the networks increases the swelling ration and decreases the porosity. Furthermore, as the ratio of PEGDA to PVA increased, WVTR ratio, cell adhesion, and elongation of the networks increased. It was also found that, when the amount of PEGDA reduced, degradation rate of the networks decreased. The results verified the non-toxic nature of PEGDA/PVA/TG hydrogel networks. Finally, the antibacterial results demonstrated that the highest antibacterial activities against bacterial pathogens is related to the TG-containing film. Therefore, PEGDA/PVA/TG hydrogel networks can be favorable wound dressings.

Localized temporal co-delivery of interleukin 10 and decorin genes using amediated by collagen-based biphasic scaffold modulates the expression of TGF-β1/β2 in a rabbit ear hypertrophic scarring model

Hypertrophic scarring (HS) is an intractable complication associated with cutaneous wound healing. Although transforming growth factor β1 (TGF-β1) has long been documented as a central regulatory cytokine in fibrogenesis and fibroplasia, there is currently no cure. Gene therapy is emerging as a powerful tool to attenuate the overexpression of TGF-β1 and its signaling activities. An effective approach may require transferring multiple genes to regulate different aspects of TGF-β1 signaling activities in a Spatio-temporal manner. Herein we report the additive anti-fibrotic effects of two plasmid DNAs encoding interleukin 10 (IL-10) and decorin (DCN) co-delivered via a biphasic 3D collagen scaffold reservoir platform. Combined gene therapy significantly attenuated inflammation and extracellular matrix components' accumulation in a rabbit ear ulcer model; and suppressed the expressions of genes associated with fibrogenesis, including collagen type I, as well as TGF-β1 and TGF-β2, while enhancing the genes commonly associated with regenerative healing including collagen type III. These findings may serve to provide a non-viral gene therapy platform that is safe, optimized, and effective to deliver multiple genes onto the diseased tissue in a wider range of tissue fibrosis-related maladies.

From prevention to diagnosis and treatment: Biomedical applications of metal nanoparticle-hydrogel composites

Recent advances in biomaterials integrate metal nanoparticles with hydrogels to generate composite materials that exhibit new or improved properties. By precisely controlling the composition, arrangement and interactions of their constituents, these hybrid materials facilitate biomedical applications through myriad approaches. In this work we seek to highlight three popular frameworks for designing metal nanoparticle-hydrogel hybrid materials for biomedical applications. In the first approach, the properties of metal nanoparticles are incorporated into a hydrogel matrix such that the composite is selectively responsive to stimuli such as light and magnetic flux, enabling precisely activated therapeutics and self-healing biomaterials. The second approach mediates the dynamic reorganization of metal nanoparticles based on environment-directed changes in hydrogel structure, leading to chemosensing, microbial and viral detection, and drug-delivery capabilities. In the third approach, the hydrogel matrix spatially arranges metal nanoparticles to produce metamaterials or passively enhance nanoparticle properties to generate improved substrates for biomedical applications including tissue engineering and wound healing. This article reviews the construction, properties and biomedical applications of metal nanoparticle-hydrogel composites, with a focus on how they help to prevent, diagnose and treat diseases. Discussion includes how the composites lead to new or improved properties, how current biomedical research leverages these properties and the emerging directions in this growing field.

Recent advances on polymeric hydrogels as wound dressings

Severe hemorrhage is a leading cause of high mortality in critical situations like disaster, accidents, and warfare. The resulting wounds could induce severe physical and psychological trauma to patients and also bring an immense socio-economic burden. Hence, rapid hemostasis and wound healing techniques have become critical initiatives for life-saving treatment. Although traditional methods relying on bandages and gauzes are effective in controlling hemorrhage, they suffer from several limitations: nonbiodegradability, being susceptible to infection, being unsuitable for the irregular wound, secondary tissue damage, and being almost ineffective for wound healing. Owing to the merits of high porosity, good biocompatibility, tunable physicochemical properties, and being beneficial for wound healing, hydrogels with excellent performance have drawn intensive attention and numerous novel effective hydrogel dressings have been widely developed. In this Review, after introducing some commonly used strategies for the synthesis of hydrogels, the most recent progress on polymer-based hydrogels as wound dressings is discussed. Particularly, their hemostasis, antibacterial, and biodegradation properties are introduced. Finally, challenges and future perspectives about the development of hydrogels for wound dressings are outlined.

The Design, Characterization and Antibacterial Activity of Heat and Silver Crosslinked Poly(Vinyl Alcohol) Hydrogel Forming Dressings Containing Silver Nanoparticles

The prompt treatment of burn wounds is essential but can be challenging in remote parts of Africa, where burns from open fires are a constant hazard for children and suitable medical care may be far away. Consequently, there is an unmet need for an economical burn wound dressing with a sustained antimicrobial activity that might be manufactured locally at low cost. This study describes and characterizes the novel preparation of a silver nitrate-loaded/poly(vinyl alcohol) (PVA) film. Using controlled heating cycles, films may be crosslinked with in situ silver nanoparticle production using only a low heat oven and little technical expertise. Our research demonstrated that heat-curing of PVA/silver nitrate films converted the silver to nanoparticles. These films swelled in water to form a robust, wound-compatible hydrogel which exhibited controlled release of the antibacterial silver nanoparticles. An optimal formulation was obtained using 5% (w/w) silver nitrate in PVA membrane films that had been heated at 140 °C for 90 min. Physical and chemical characterization of such films was complemented by in vitro studies that confirmed the effective antibacterial activity of the released silver nanoparticles against both gram positive and negative bacteria. Overall, these findings provide economical and simple methods to manufacture stable, hydrogel forming wound dressings that release antibiotic silver over prolonged periods suitable for emergency use in remote locations.

The Development of Solvent Cast Films or Electrospun Nanofiber Membranes Made from Blended Poly Vinyl Alcohol Materials with Different Degrees of Hydrolyzation for Optimal Hydrogel Dissolution and Sustained Release of Anti-Infective Silver Salts

Introduction: We previously described the manufacture and characterization of hydrogel forming, thin film, anti-infective wound dressings made from Poly Vinyl Alcohol (PVA) and silver nanoparticles, crosslinked by heat. However, these films were designed to be inexpensive for simple manufacture locally in Africa. In this new study, we have further developed PVA dressings by manufacturing films or electrospun membranes, made from blends of PVA with different degrees of hydrolyzation, that contain silver salts and degrade in a controlled manner to release silver in a sustained manner over 12 days. Methods: Films were solvent cast as films or electrospun into nanofibre membranes using blends of 99 and 88% hydrolyzed PVA, containing 1% w/w silver sulphadiazine, carbonate, sulphate, or acetate salts. Dissolution was measured as weight loss in water and silver release was measured using inductively coupled plasma (ICP) analysis. Results: Cast films generally stayed intact at PVA 99: PVA 88% ratios greater than 40:60 whereas electrospun membranes needed ratios greater than 10:90. Films (40:60 blend ratio) and membranes (10:90) all released silver salts in a sustained fashion but incompletely and to different extents. Electrospun membranes gave more linear release patterns in the 2–12 day period and all salts released well. Conclusion: Blended PVA cast films offer improved control over hydrogel dissolution and silver release without the need for high temperature crosslinking. Blended PVA electrospun membranes further improve membrane dissolution control and silver release profiles. These blended PVA films and membranes offer improved inexpensive systems for the manufacture of long lasting anti-infective hydrogel wound dressings.

Green Synthesis of Silver Nanoparticles and Evaluation of Their Antibacterial Activity against Multidrug-Resistant Bacteria and Wound Healing Efficacy Using a Murine Model

Green nanotechnology has significant applications in various biomedical science fields. In this study, green-synthesized silver nanoparticles, prepared by using Catharanthus roseus and Azadirachta indica extracts, were characterized using UV-Vis spectroscopy, dynamic light scattering, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Silver nanoparticles (Ag NPs) synthesized from leaf extracts of C. roseus and A. indica effectively inhibited the growth of multidrug-resistant (MDR) bacteria isolated from patients with septic wound infections. The maximum bacteriolytic activity of the green-synthesized Ag NPs of C. roseus and A. indica against the MDR bacterium K. Pneumoniae was shown by a zone of inhibition of 19 and 16 mm, respectively. C. roseus Ag NPs exhibited more bacteriolytic activity than A. indica Ag NPs in terms of the zone of inhibition. Moreover, these particles were effective in healing wounds in BALB/c mice. Ag NPs of C. roseus and A. indica enhanced wound healing by 94% ± 1% and 87% ± 1%, respectively. Our data suggest that Ag NPs from C. roseus and A. indicia ameliorate excision wounds, and wound healing could be due to their effective antimicrobial activity against MDR bacteria. Hence, these Ag NPs could be potential therapeutic agents for the treatment of wounds.

An Alkaline Based Method for Generating Crystalline, Strong, and Shape Memory Polyvinyl Alcohol Biomaterials

Strong, stretchable, and durable biomaterials with shape memory properties can be useful in different biomedical devices, tissue engineering, and soft robotics. However, it is challenging to combine these features. Semi-crystalline polyvinyl alcohol (PVA) has been used to make hydrogels by conventional methods such as freeze-thaw and chemical crosslinking, but it is formidable to produce strong materials with adjustable properties. Herein, a method to induce crystallinity and produce physically crosslinked PVA hydrogels via applying high-concentration sodium hydroxide into dense PVA polymer is introduced. Such a strategy enables the production of physically crosslinked PVA biomaterial with high mechanical properties, low water content, resistance to injury, and shape memory properties. It is also found that the developed PVA hydrogel can recover 90% of plastic deformation due to extension upon supplying water, providing a strong contraction force sufficiently to lift objects 1100 times more than their weight. Cytocompatibility, antifouling property, hemocompatibility, and biocompatibility are also demonstrated in vitro and in vivo. The fabrication methods of PVA-based catheters, injectable electronics, and microfluidic devices are demonstrated. This gelation approach enables both layer-by-layer and 3D printing fabrications.

Facile Fabrication of Silicon(IV)Phthalocyanine-Embedded Poly(vinyl alcohol)-Based Antibacterial and Antifouling Interfaces

Interest in the photodynamic inactivation of bacteria as an alternative method to antibiotic treatment continues to grow. Based on this approach, light-activated anti-infective interfaces could be fabricated via incorporation of photosensitizers into the polymer-based materials. In order to combine photobactericidal and antifouling functions, the choice of the carrier polymer is of particular significance: it should enable fast and effective conjugation of photosensitizer and reduce the formation of bioburden on the artificial material in a biological environment. This study reports one-pot fabrication and characterization of two silicon(IV)phthalocyanine /poly(vinyl alcohol)-based electrospun mats. The method relies on the thermal cross-linking of components by esterification using sebacic acid as a cross-linking agent. Fabricated flexible mats showed photosensitizer-dependent antibacterial photoactivity against different Gram-positive bacteria with low cytotoxic effects on human fibroblasts and were effective against bacterial attachment, as an early step toward future biofilm formation. This work provides practical guidelines in developing photoactive materials and interfaces that can be used in nonadhesive wound dressings, food packaging, water, and air filtration.

High strength polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel fabricated by Cold-Drawn method for cartilage tissue substitutes

Poly (vinyl alcohol) (PVA) hydrogel has been considered as promising cartilage replacement materials due to its excellent characteristics such as high water content, low frictional behavior and excellent biocompatibility. However, lack of sufficient mechanical properties and cytocompatibility are two key obstacles for PVA hydrogel to be applied as cartilage substitutes. Herein, Polyacrylic acid (PAA) has been introduced into PVA hydrogel to balance these problems. Compared with pure PVA hydrogel, PVA/PAA hydrogel has the equal excellent biocompatibility, and its cell adhesion is significantly improved. In order to further improve the mechanical properties of hydrogels, Cold-Drawn treatment of hydrogels is performed in this paper. Compared to pure 12% PVA hydrogel, 40.8-fold, 50.8-fold, and 46.8-fold increase in tensile strength, tensile modulus, and toughness, respectively, which can be obtained from 12% PVA/PAA Cold-Drawn hydrogel. These biocompatible composite hydrogels have a great application potential as cartilage tissue substitutes.

A Comprehensive Review on Bio-Nanomaterials for Medical Implants and Feasibility Studies on Fabrication of Such Implants by Additive Manufacturing Technique

Nanomaterials have allowed significant breakthroughs in bio-engineering and medical fields. In the present paper a holistic assessment on diverse biocompatible nanocomposites are studied. Their compatibility with advanced fabrication methods such as additive manufacturing for the design of functional medical implants is also critically reviewed. The significance of nanocomposites and processing techniques is also envisaged comprehensively in regard with the needs and futures of implantable medical device industries.

Analysis of the physicochemical properties of antimicrobial compositions with zinc oxide nanoparticles

In this study, an antimicrobial composition based on polyvinyl alcohol (PVA) and zinc oxide (ZnO) was developed. The aim of the work was to obtain a film-forming product for antimicrobial treatment of surfaces. To improve the physical, mechanical, and film-forming properties of the compositions, three natural stabilizing agents were added to the formulation: gelatine, guar gum and hydroxyethyl cellulose. Formulations with different concentrations of each stabilizer were tested, and the physicochemical properties of the obtained products were measured. The size of zinc oxide particles in obtained compositions varied from 232 to 692 nm. The compositions had a slight acidic nature. Their pH ranged from 6.84 to 6.99. The average density of products was equal to 1.37 × 10³ (kg/m³). It was confirmed that zinc oxide nanoparticles do not penetrate through a model dermal membrane which is a desired effect concerning their toxicity. The antimicrobial activity of the obtained compositions was assessed against Aspergillus niger strain. After 24 h of studying, the growth inhibition was in 71% greater than in reference material. After statistical analysis of the results, it was concluded in order to achieve the most desirable physicochemical and utilitarian properties, the concentrations of gelatine, guar gum and hydroxyethylcellulose should be equal to 0.5%, 0.03% and 0.055%, respectively.