Alcohol Hydrogel Research Articles

An environment-stable and tough wearable sensor enabled by xanthan gum-assisted hydrogel

Wearable sensors based on ionic hydrogels have attracted increasing attention, but practical application is often hampered by poor environmental tolerance. Here, an environment-stable and tough hydrogel was constructed by introducing glycerin, sodium chloride and xanthan gum into a polyvinyl alcohol hydrogel network. Hydrogen bonds were formed among glycerin, xanthan gum and polyvinyl alcohol chains to enhance the toughness of hydrogel. Furthermore, the salting-out effect of polyvinyl alcohol chains induced by sodium chloride also improved the strength of hydrogel. Besides, the hydrogel was highly sensitive to mechanical deformation of tensile and compressive strain. The obtained hydrogel with sensitivity was capable of serving as a wearable sensor for monitoring human motions including speaking, bending articulation and so on. Notably, the hydrogel still maintained flexibility, toughness and conductivity under subzero or ambient conditions for a long time. This simple method paves an effective way for designing environment-stable and tough hydrogels.

Polyvinyl Alcohol Hydrogel Hemiarthroplasty of First Metatarsophalangeal Joint Hallux Rigidus.

Background Hallux rigidus (HR) is the most common arthritic condition of the foot. Although first metatarsophalangeal joint (MTPJ) arthrodesis has been the historical gold-standard treatment, polyvinyl alcohol (PVA) hydrogel implants have gained popularity as a joint-sparing technique. However, recent studies have shown variable failure rates of PVA hydrogel implants. The purpose of this study was to report the five-year experience with PVA hydrogel implants performed by a single surgeon. Methodology Health records were queried from August 2016 to 2021 for patients who underwent primary PVA hydrogel implant hemiarthroplasty for symptomatic late-stage HR. Patient demographics and postoperative outcomes variables were evaluated. Kaplan-Meier analysis was used to evaluate implant survival. A total of 146 PVA hydrogel implant procedures were performed with a minimum six-month follow-up. Results The majority of patients were female (n = 103, 70.5%), with a mean age of 58.1 (±10.1) years, body mass index of 27.3 (±5.2) kg/m2, and American Society of Anesthesiologists score <3 (n = 131, 89.7%).The majority had stage II or III disease (n = 115, 78.8%). Patients experienced significant improvement in visual analog scale score (p < 0.0001) and hallux dorsiflexion (p = 0.0005). There were 22 (15.1%) complications, including implant subsidence (n = 15, 10.3%), deep infection (n = 6, 4.1%), and hypertrophic ossification (n = 1, 0.7%). Revision surgeries were required in 12.3% (n = 18) of patients at an average of 9.4 (±9.2) months postoperatively. This included nine (6.2%) revision PVA hydrogel implant procedures and nine (6.2%) first MTJP arthrodesis. The one- and two-year survival rates for MTPJ arthrodesis (n = 9) were 95.9% and 86.3%, respectively. Conclusions In the largest single-surgeon series reported, first MTPJ hemiarthroplasty with a PVA hydrogel implant significantly improved pain and hallux dorsiflexion at an average of 14.5 months postoperatively. There was a high two-year survivorship of 86.3% until failure which required first MTPJ arthrodesis. Future studies should be performed to refine the indications for PVA hydrogel implants and identify risk factors.

A Comparison of PROMIS Scores in Patients Treated with First Metatarsophalangeal Joint Arthrodesis and Polyvinyl Alcohol Hydrogel Implant Hemiarthroplasty for Hallux Rigidus

Introduction/Purpose: Current literature shows similar clinical outcomes between first metatarsophalangeal joint arthrodesis and polyvinyl alcohol hydrogel (synthetic cartilage implant or SCI) hemiarthroplasty in the treatment of hallux rigidus; however, prior studies have not reported validated patient-reported outcome measures. To our knowledge, this is the first study to compare patient-reported outcome measures using the validated Patient Reported Outcomes Measurement Information System (PROMIS) in patients treated for hallux rigidus with metatarsophalangeal joint arthrodesis and SCI hemiarthroplasty. In addition, this novel study provides comparative data of the complication and revision rates for each procedure. Methods: A retrospective review of prospectively collected data within an institutional registry identified 101 patients who underwent metatarsophalangeal joint arthrodesis and 82 patients who underwent SCI hemiarthroplasty for treatment of hallux rigidus between January 2016 and June 2022. Chart review was performed to obtain demographic information, complications, and revision rates. Preoperative, 1-year, and 2-year PROMIS scores were obtained from the registry and confirmed via chart review. Equivalence testing was performed using two one sided t-tests (TOST) and setting a +/-5 unit margin of difference as the clinically meaningful difference to determine if there was a difference in PROMIS scores between groups. Linear regression models were also utilized to compare adjusted postoperative PROMIS scores between the two cohorts. For the equivalence testing, a p-value &gt; 0.05 indicated a statistically significant result. Results: Demographic information and preoperative hallux rigidus severity between the cohorts showed no statistically significant difference (Table 1). The SCI cohort had no intra-operative or post-operative wound complications, but one patient within the MTP fusion cohort was treated for a superficial wound infection. The SCI group had six patients revised to MTP fusions within 3- years due to continued pain and/or implant subsidence. The MTP fusion group had 2 patients revised due to non-union and 13 patients that had symptomatic hardware requiring removal. Equivalence comparison of PROMIS scores showed the SCI cohort had significantly worse pain intensity scores at 2 years and significantly less improvement in pain intensity scores from pre- operative to 1-year post-op (Table 2). There were no differences found between cohorts for other PROMIS domains. Conclusion: For the treatment of hallux rigidus, the SCI hemiarthroplasty and metatarsophalangeal joint arthrodesis have equivalent outcomes for all PROMIS domains except the pain intensity domain. While patients in both cohorts had improvement in pain from pre-operative to post-operative time points, SCI was not as effective as first MTP fusion at relieving pain intensity at a follow-up of 2 years. While SCI is a motion-sparing procedure, patients with a primary goal of improving pain may be better suited for first MTP joint arthrodesis. Tables demonstrating the comparisons of both the preoperative demographic data as well as demonstrating the PROMIS scores across different time periods (preoperative, 1 year and 2 years).

Asymmetric porous composite hydrogel patch for microenvironment-adapted repair of contaminated abdominal wall defects

Effective antibacterial property and long-term mechanical support are essential for the repair of complex abdominal wall defects associated with infection. However, clinically available repair materials often fail to meet these requirements, resulting in high surgical failure rate and complications. In this study, an asymmetric porous composite hydrogel patch (cCS/PVA@BAC) with antibacterial, anti-adhesion, pro-healing, and durable mechanical support properties is designed for the efficient repair of contaminated abdominal wall defects. By stepwise phase-conversion and soaking method, robust and stable polyvinyl alcohol hydrogel (PVAH) is integrated with the biocompatible multicomponent hydrogel made of chitosan and carboxymethyl chitosan (cCS), and benzalkonium chloride (BAC) is loaded to enhance the antibacterial property. The cCS layer of cCS/PVA@BAC has an extracellular matrix-like porous structure, which can promote fibroblasts adhesion and wound healing. In contrast, the PVAH layer on the other side with a smooth and dense structure, which can reduce fibroblasts adhesion and prevent visceral adhesion. In addition, the composite hydrogel patch has good anti-swelling and anti-deformation properties as well as stable mechanical strength, thus can withstand high intraperitoneal pressure in the wet internal microenvironment. The loaded BAC can efficiently kill bacteria and improve the local inflammatory microenvironment. With these advantages, cCS/PVA@BAC can significantly reduce inflammation, promote tissue remodeling, and accelerate the healing of contaminated abdominal wall defects in the rat model. These findings suggest a potential use of multifunctional hydrogel patch as an ideal material for effective repair of contaminated soft tissue defects.

Vanillin/fungal-derived carboxy methyl chitosan/polyvinyl alcohol hydrogels prepared by freeze-thawing for wound dressing applications

In this study, we developed hydrogels using polyvinyl alcohol (PVA), vanillin (V), and a fungus-derived carboxymethyl chitosan (FC) using a freeze-thaw-based method. These hydrogels were strengthened by bonding, including Schiff's base bonding between V and FC and hydrogen bonding between PVA, FC, and V. The physiological properties of these PFCV hydrogels were characterized by FTIR, TGA, compressive mechanical testing, and rheology and water contact angle measurements. FTIR spectra confirmed the effective integration of FC and V into the PVA network. TGA results showed that FC and V enhanced the thermal stability of PFCV hydrogels. Mechanical tests showed increasing the amount of V reduced mechanical properties but did not alter the elastic character of hydrogels. SEM images displayed a well-interconnected porous structure with excellent swelling capacity. In addition, we examined biological properties using cell-based in vitro studies and performed antibacterial assessments to assess suitability for potential wound dressing applications. Prestoblue™ and live/dead cell analysis strongly supported skin fibroblast attachment and viability, DPPH assays indicated substantial antioxidant activity, and PFCV hydrogels showed enhanced antibacterial effects against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). In summary, incorporating V and FC into PVA hydrogels appears to be attractive for wound dressing applications.

Preparation of 3D flexible SERS substrates by mixing gold nanorods in hydrogels for the detection of malachite green and crystal violet.

Asimple and cost-effective fabrication method of gold nanorods (AuNRs) nanoparticles hybridized with polyvinyl alcohol hydrogel(AuNR/PVA) for SERS substrateis described. The AuNR/PVAachieves the control of inter-particle nanogap by modulating the density of gold nanorods, and inter-particle nanogap by the spatial deformation of the hydrogel, and the reduction of the gap between the AuNRs deposited on hydrogel makes the SERS enhancement. In addition, the AuNR/PVA substrate maintains high SERS activity after more than 100 cycles of bending and storage in air for 30 days, and the substrate possesses high sensitivity and high reproducibility. Combining a flexible and transparent surface-enhanced Raman spectroscopy (SERS) substrate for in situ detection with a small portable Raman can be applied to scenarios such as environmental detection and hazardous materials detection. The substrate showed excellent SERS activity against malachite green (MG) and crystal violet (CV) with limits of detection of 1.18 × 10-13 M and 7.17 × 10-12 M, respectively. The usability of the proposed SERS substrate was demonstrated by detecting the above contaminants in aquatic water. This work not only utilizes a cost-effective method for mass production but also provides a reliable and convenient platform for the preparation of other noble metal flexible substrates.

Spatial cell fate manipulation of human pluripotent stem cells by controlling the microenvironment using photocurable hydrogel.

Human pluripotent stem cells (hPSCs) dynamically respond to their chemical and physical microenvironment, dictating their behavior. However, conventional in vitro studies predominantly employ plastic culture wares, which offer a simplified representation of the in vivo microenvironment. Emerging evidence underscores the pivotal role of mechanical and topological cues in hPSC differentiation and maintenance. In this study, we cultured hPSCs on hydrogel substrates with spatially controlled stiffness. The use of culture substrates that enable precise manipulation of spatial mechanical properties holds promise for better mimicking in vivo conditions and advancing tissue engineering techniques. We designed a photocurable polyethylene glycol-polyvinyl alcohol (PVA-PEG) hydrogel, allowing the spatial control of surface stiffness and geometry at a micrometer scale. This versatile hydrogel can be functionalized with various extracellular matrix proteins. Laminin 511-functionalized PVA-PEG gel effectively supports the growth and differentiation of hPSCs. Moreover, by spatially modulating the stiffness of the patterned gel, we achieved spatially selective cell differentiation, resulting in the generation of intricate patterned structures.

Synergistic crosslinking effect of hydroxyethyl cellulose and montmorillonite on the improvement of mechanical and electrochemical properties of polyvinyl alcohol hydrogel

Flexible solid-state zinc-ion battery is promising energy technology with low cost, excellent performance, and safety. However, the mechanical properties of flexible electrolytes are severely limited. Here, hydroxyethyl cellulose (HEC) and montmorillonite (MMT) were introduced into a polyvinyl alcohol (PVA) matrix to prepare a novel composite hydrogel using a repeated freeze-thaw method. Both organic HEC and inorganic MMT could form hydrogen bonds with PVA molecular chains, acting as crosslinkers to construct a well-networked hydrogel structure. The synergistic effect of these two crosslinkers significantly enhanced the mechanical properties of the composite hydrogel. The composite hydrogel prepared with 3 wt% HEC and 2 wt% MMT (denoted as P–H3%-M2%) exhibited a 242.6% increase in tensile strength, 78.6% increase in elongation at break, and 970.1% increase in compressive strength compared to pure PVA hydrogel. P–H3%-M2% hydrogel also demonstrated a high electrolyte uptake rate (199.15%) and ion conductivity (24.6 mS cm−1). When assembled in a Zn symmetric battery, it maintained stable operation for 3000 h with a low polarization voltage of approximately 70 mV. Furthermore, P–H3%-M2% hydrogel assembled in a Zn//MnO2 battery exhibited a discharge specific capacity of 218 mAh g−1 at a current density of 0.15 A g−1, with 91% capacity retention after 450 cycles. At a higher current density of 1.5 A g−1, it showed a discharge specific capacity of 108 mAh g−1, which is 4.5 times higher than that of the PVA hydrogel battery, demonstrating excellent rate performance.

A hydrogel-based ratiometric fluorescent sensor relying on rhodamine B labelled AIE-featured hyperbranched poly(amido amine) for heparin detection

The fluorescent flexible sensor for point-of-care quantification of clinical anticoagulant drug, Heparin (Hep), is still an urgent need of breakthrough. In this research, a hyperbranched poly(amido amine) (HPA) was decorated with tetraphenylethene (TPE) and Rhodamine B (RhB), constructing a ratiometric fluorescent sensor (TR-HPA) for Hep. When the sensor was exposed to Hep, the TPE units within the probe skeleton would aggregate, resulting in an increasing fluorescent emission at 483 nm. The 580 nm of fluorescence came from RhB enhance, simultaneously, due to the fluorescence resonance energy transfer. As a result, there are two good linear correlation between the fluorescence emission ratio (E483/E580) of TR-HPA and the Hep concentration over a range of 0–1.0 μM, with a low limit of detection of 3.0 nM. Furthermore, we incorporate the TR-HPA probe into a polyvinyl alcohol (PVA) hydrogel matrix to create a flexible fluorescent sensing system platform, denoted as TR-HPA/PVA. This approach offers a straightforward visual detection method by causing a fluorescence color change from pink to blue when trace amounts of Hep are present. The hydrogel-based fluorescent sensor streamlines the detection procedures for Hep in biomedical applications. It shows great potential in rapid and point-of-care human blood clotting condition monitoring, making it suitable for next-generation wearable medical devices.

A novel approach to wound healing: Green synthetic nano-zinc oxide embedded with sodium alginate and polyvinyl alcohol hydrogels for dressings

Wound healing constitutes a formidable challenge within the healthcare system, attributable to infection risks and protracted recovery periods. The pressing need for innovative wound healing methods has spurred the urgency to develop novel approaches. This study sought to advance wound healing by introducing a novel approach employing a composite sponge dressing. The composite sponge dressing, derived from LFL-ZnO (synthesized through the green methodology utilizing Lactobacillus plantarum ZDY2013 fermentation liquid), polyvinyl alcohol (PVA), and sodium alginate (SA) via a freeze–thaw cycle and freeze-drying molding process, demonstrated notable properties. The findings elucidate the commendable swelling, moisturizing, and mechanical attributes of the SA/LFL-ZnO/PVA composite sponge dressing, characterized by a porous structure. Remarkably, the dressing incorporating LFL-ZnO exhibited substantial inhibition against both methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (S. aureus). Hemolysis and cytotoxicity tests corroborated the excellent biocompatibility of the sponge dressing. In vivo evaluation of the therapeutic efficacy of the 1 mg/mL LFL-ZnO composite dressing on scald wounds and S. aureus-infected wounds revealed its capacity to accelerate wound healing and exert pronounced antibacterial effects. Consequently, the composite sponge dressings synthesized in this study hold significant potential for application in wound treatment.

Nature-Inspired Molecular-Crowding Enabling Wide-Humidity Range Applicable, Anti-Freezing, and Robust Zwitterionic Hydrogels for On-Skin Electronics.

Hydrogels are currently in the limelight for applications in soft electronics but they suffer from the tendency to lose water or freeze when exposed to dry environments or low temperatures. Molecular crowding is a prevalent occurrence in living cells, in which molecular crowding agents modify the hydrogen bonding structure, causing a significant reduction in water activity. Here, a wide-humidity range applicable, anti-freezing, and robust hydrogel is developed through the incorporation of natural amino acid proline (Pro) and conductive MXene into polyvinyl alcohol (PVA) hydrogel networks. Theoretical calculations reveal that Pro can transform "free water" into "locked water" via the molecular-crowding effect, thereby suppressing water evaporation and ice forming. Accordingly, the prepared hydrogel exhibits high water retention capability, with 77% and 55% being preserved after exposure to 20 °C, 28% relative humidity (RH)and 35 °C, 90% RH for 12h. Meanwhile, Pro lowers the freezing temperature of the hydrogel to 34 °C and enhances its stretchability and strength. Finally, the PVA/Pro/MXene hydrogels are assembled as multifunctional on-skin strain sensors and conductive electrodes to monitor human motions and detect tiny electrophysiological signals. Collectively, this work provides a molecular crowding strategy that will motivate researchers to develop more advanced hydrogels for versatile applications.

Electrical Resistivities of PVA/Activated Carbon-Based Hydrogels

This study investigates the physical and electrical properties of the polyvinyl alcohol (PVA) hydrogel incorporated with edible Activated Carbon (AC). Three samples, namely PVA, PVA/AC 0.5, and PVA/AC 1.0 were prepared using the freeze-thaw method. The samples underwent six freeze-thaw cycles, each consisting of freezing at –25°C for 20 hours and subsequent exposure to room temperature for 4 hours. The porous network of hydrogel is attributed to the hydroxyl groups of PVA, resulting from the intermolecular cross-linking of PVA chains. The edible AC was uniformly dispersed within the hydrogel network, leading to a reduction in hydrogel pores. As a result, the electrical resistivity of PVA, PVA/AC 0.5, and PVA/AC 1.0 hydrogels measured 1052.9 ± 165.0 Ω.cm, 403.1 ± 29.2 Ω.cm, and 59.9 ± 4.7 Ω.cm, respectively. The incorporation of edible AC significantly decreased the resistivity of the hydrogel. So, this hydrogel is promising for biomedical and edible electronics applications.

Spongy polyelectolyte hydrogel for efficient Solar-Driven interfacial evaporation with high salt resistance and compression resistance

The hydrogel-based evaporator for interface evaporation provides a method for sustainable freshwater production. However, salt accumulation on the surface of the steam generator affects light absorption and reduces steam generation efficiency. Achieving a high-performance, salt-resistant steam generator remains challenging. Here, sponge-like polyelectrolyte composite hydrogel-based solar steam generator (MPS) is reported. The steam generator is designed with an interpenetrating network topology and is made by in-situ polymerizing sodium polyacrylate (P(SA)) in a sponge-like polyvinyl alcohol (PVA) hydrogel framework, using molybdenum disulfide (MoS2) as a photothermal conversion material. Through the foaming process, MPS achieves self-floating and good water transportation performance, which enhances the thermal localization effect on the hydrogel surface and improves energy utilization efficiency (92.95 %), enabling efficient evaporation (3.22 kg m−2h−1). Meanwhile, due to the coupling of P(SA), MPS exhibits excellent salt resistance, maintaining a long-term evaporation rate of 2.8 kg m−2h−1 in high concentration saltwater (20 wt%). The porous structure and interconnected polymer chains enhance the mechanical performance of MPS, making it highly compressible and convenient for collecting freshwater marine and wilderness environments. The preparation strategy of MPS provides a feasible method to simultaneously improve the performance and durability of the interface steam generator in practical applications.

Hydrogel membrane composite reduces fouling and retains ammonium efficiently

The recovery of pure water and valuable substances from wastewater is a major challenge in the context of the circular economy, requiring advanced separation methods. However, actual membrane separation techniques such as forward osmosis are limited by membrane fouling and selectivity. Here, we synthesized composite membranes by crosslinking polyvinyl alcohol hydrogel, using both glutaraldehyde and borax as crosslinking agents, on top of cellulose ester membranes. We tested these composite membranes on model and real wastewater. Results show that the composite membranes retain ammonium effectively, maintain surface electroneutrality, and exhibit remarkable resistance to fouling by organic and biological contaminants. This is explained by the high hydrophilicity of the membrane surface after application of a hydrogel layer.

Nanoclay particles as a stem cell adhesion factor in polyvinyl alcohol hydrogel‐based wound dressings

AbstractAs the primary goal in the wound care intervention is the promotion of rapid wound healing, researchers sought to find a remedy. In this progression course, nanocomposite‐based hydrogels have attracted the attention. Herein, we used a polyvinyl alcohol (PVA) hydrogel in combination with two forms of clay nanoparticles, namely unmodified montmorillonite (MONT) and modified (OMONT), to fabricate a nanocomposite‐based hydrogels and combat the lack of stem cells' adhesion to PVA, followed by seeding of adipose‐derived stem cells (ADSCs) on them. To investigate the characteristics of these constructs, corresponding tests were performed. The Young's modulus and elongation at break of PVA/5% OMONT were 3.7 ± 0.014 and 800 ± 35, respectively, which were higher than those of PVA/5% MONT (3 ± 0.03 and 320 ± 14). In addition, the hardness of the modified group (7.2 ± 0.07) was lower than the unmodified one (9.8 ± 0.07). The water vapor transmission rate (WVTR) in the OMONT group was 39 ± 0.28, which was lower than PVA/5% MONT (46 ± 4.24). Hence, ADSCs/PVA montmorillonite dressing may improve wound healing and provide a new way to employ stem cells, significantly impacting skin tissue engineering safely.Highlights Modified montmorillonite had higher stem cell binding. The lack of stem cells' adhesion to polyvinyl alcohol (PVA) was solved. Adipose‐derived stem cells/PVA montmorillonite dressing may improve wound healing. It is a novel promising approach for skin tissue engineering.

A Method Based on a Modified Fluorescence In Situ Hybridization (FISH) Approach for the Sensing of Staphylococcus aureus from Nasal Samples.

Staphylococcus aureus is a major source of bacteremia and develops several complications, causing high morbidity and mortality. Rapid identification and detection of these bacteria have become an important issue for biomedical applications. Herein, an optical method based on a modified fluorescence in situ hybridization (FISH) approach has been established using DNA hybridization technology for the swift detection of pathogenic S. aureus from clinical samples. The platform was constructed with single-stranded genomic DNA and microbial colony by directly immobilizing in agarose-polyvinyl alcohol (AG-PVA) hydrogel on the surface of a glass slide. The probe was based on an elongation factor encoding the tuf gene, which binds with equal affinity to single-stranded DNA targets as well as surface proteins on microbial cells. The probe was labeled with MFP488 fluorophore having excitation wavelength 501nm. The hybridization of the labeled probe with the target DNA and surface proteins was carried out under optimal FISH conditions, and the detection of bacteria was based on temporary field excitation of the labeled probe under a fluorescence microscope. Positive hybridization signals were detected by high fluorescence intensity. In comparison to genomic DNA, robust signals were observed with microbial cells, perhaps due to the moonlighting effect of the elongation factor Tu (Ef-Tu) expressed on the surface of bacterial cells. The applicability of the developed platform was tested on pediatric nasal samples, and results were verified with real-time qPCR. The designed platform is stable and sensitive, and after detailed optimization, a portable structure for on-site detection of pathogenic bacteria from clinical samples can be produced.

Xanthan gum‐enhanced polyvinyl alcohol hydrogel toward flexible sensor

AbstractIonic conductive hydrogels attracted much attention for applying as wearable sensors, but most hydrogel sensors were not strong enough to withstand repeated sensing because of their low mechanical strength. Here, xanthan gum and sodium chloride were introduced into the polyvinyl alcohol hydrogel system for constructing hydrogels with high mechanical strength due to the hydrogen bonds formed between polyvinyl alcohol and gum xanthan as well as the chain entanglement of polyvinyl alcohol. Meanwhile, the hydrogel was highly sensitive to mechanical deformation because of the existence of free ions provided by sodium chloride. As a result, the hydrogel could serve as sensors for perceiving various body motions, with the advantages of fast response, reproducibility and durability for repeated stretching or compression. The strategy of xanthan gum‐enhanced hydrogel fuels an exciting new direction for hydrogel‐based wearable sensors.

Sodium lignosulfonate doped polyvinyl alcohol-based hydrogel conductive composites based on ion-specific effects with continuously tunable mechanical properties and excellent conductive sensing properties

Hydrogels have great application prospects in the fields of bionics, soft tissue probes, and motion detection, etc. However, the high water content and loose cross-linker structure of hydrogels lead to weak mechanical properties, which limits their application and development. Therefore, in this study, sodium lignosulfonate doped polyvinyl alcohol hydrogels (PVA/LS) were constructed using polyvinyl alcohol as the matrix and sodium lignosulfonate as the filler; the hydrogels were also treated with different ionic solutions to construct ion-responsive hydrogels (PVA/LS/ION); and ion-conducting hydrogels (PVA/LS/CL) were constructed by the change of the concentration of sodium chloride (NaCl) solution. The hydrophilicity of the polyvinyl alcohol (PVA) molecular chain was changed by different ions, resulting in either water absorption (salting in) or dehydration (salting out), and the hydrogel mechanical properties could be adjusted over a wide range (tensile strength: 77 kPa ∼ 3.26 MPa; elongation at break: 290 ∼ 870%; modulus: 24 ∼ 563 kPa; toughness: 96 kJ/m3 ∼ 14.1 MJ/m3). In addition, the hydrogels have good conductivity regulation (1.09 ∼ 2.72 S/m) and sensing properties, with GF values up to 1.23, and sensitive and stable strain sensing properties. This work provides useful insights into the application of ion-specific effects to the field of hydrogels.

High-conductivity and long-term stability strain sensor based on silk fibroin and polyvinyl alcohol hydrogels

Conductive hydrogels as promising candidates of wearable electronic have attracted considerable interest in health monitoring, multifunctional electronic skins, and human-machine interfaces. However, to simultaneously achieve excellent electrical properties, long-term stability, and water vapor permeability of conductive hydrogels remains a challenge. Herein, a highly conductive hydrogel (MPRS) with high breathability (5.90 mg∙cm−2∙h−1), excellent electrical conductivity (6.67 S/m), high elongation (315%), and remarkable water retention properties was prepared adopting cold freeze-thawing method. MXene, poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS), and reduced graphene oxide were used as conductive materials, while silk fibroin (SF) and polyvinyl alcohol (PVA) were used as the gel matrix. Lithium chloride solution was used as a solvent during the preparation process. The strain sensor based on this hydrogel demonstrates rapid response (0.33 s) and recovery ability (0.31 s) to strain stimuli. Upon 250 cycles of stretching at 35% strain, the output signal remains stable and highly repeatable, ensuring accurate detection of human joint movements and facial expressions. The fabrication of flexible electrodes using the hydrogel enabled real-time monitoring of human electromyography and electrocardiogram signals. The applications in a 2D sensor array and human-machine interaction interfaces also proved the excellent performance of this conductive hydrogels in wearable sensor.

Conception of pH-sensitive calcium alginate/poly vinyl alcohol hydrogel beads for controlled oral curcumin delivery systems. Antibacterial and antioxidant properties

Curcumin, a bioactive compound derived from the rhizome of Curcuma longa, has gained widespread attention for its potential therapeutic properties, including anti-inflammatory, antioxidant and anticancer effects. However, its poor aqueous solubility, instability and limited bioavailability have hindered its clinical applications.New beads formulations based on sodium alginate biopolymer (SA) and poly vinyl alcohol (PVA) were successfully prepared and evaluated as a potential drug vehicle for extended release of curcumin (Cur). Pristine and curcumin loaded calcium alginate/poly vinyl alcohol beads (CA/PVA and CA/PVA/Cur) at different compositions of SA and PVA were prepared by an ionotropic gelation method of SA followed by two freeze-thawing (FT) cycles for further crosslinking of PVA. Characterization techniques, such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV–Visible spectroscopy, thermogravimetric analysis (TGA) and x-ray diffraction (XRD) were used to confirm the successful microencapsulation of curcumin within the CA/PVA microcapsules. Furthermore, the swelling of pristine beads, pH-sensitive properties and in vitro release studies of curcumin loaded beads were investigated at 37 °C in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and simulated colonic fluid (SCF). The effect of the polymer blend ratio, the encapsulation efficiency (EE %) of curcumin, the loading capacity (LC μg/mg), the sphericity factor (SF), the antioxidant activity of the elaborated beads and their antimicrobial properties against bacteria and fungi were just as much evaluated.The obtained results indicate that the swelling and the behavior of the developed beads were influenced by the pH of the test medium and the PVA content. The introduction of PVA into the SA matrix greatly enhanced the physicochemical properties, the encapsulation efficiency and the loading capacity of the elaborated microparticles. Results also suggested that the antioxidant activity of the loaded beads (CA/PVA/Cur) showed a higher DPPH radical scavenging activity while the bacterial and fungal strains proved sensitive to the different formulations used in the assay. Moreover, the important drug encapsulation efficiency and the sustainable drug release of these materials make them promising for the development of new drug carrier systems for colon targeting.