Aging behavior of PVA hydrogels for soft tissue applications after in vitro swelling using osmotic pressure solutions

Photonic double-network hydrogel dressings for antibacterial phototherapy and inflammation regulation in the general management of cutaneous regeneration

The treatment of festering pathogenic bacteria-induced skin wounds with increased inflammation is an ongoing challenge. The traditional antibacterial photothermal therapy always results in localized hyperthermia (over 50 °C), which inevitably delays tissue recovery. To address this serious issue, we devise a novel photonic hydrogel by integrating urchin-like Bi₂S₃ nano-heterojunctions (nano-HJs) into double-network hydrogels for infected skin regeneration. The synergy of NIR-triggered heat and ROS enables the hydrogels to achieve a rapid germicidal efficacy against bacteria within 15 min at mild temperature (below 50 °C). In vitro cell analysis results revealed that the photonic hydrogels exhibit superior cytocompatibility even after NIR illumination. More importantly, an in vivo study demonstrated that the photonic hydrogel dressings have a robust ability of accelerating contagious full-thickness wound regeneration through debriding abscesses, eliminating pathogens, improving collagen deposition, promoting angiogenesis, and adjusting the inflammation state. This photonic hydrogel system provides a general management strategy for the remedy of infectious wounds, where the incorporation of nano-HJs endows the hydrogels with the photodisinfection ability; in addition, the multifunctional hydrogels alleviate the damage from overwhelming heat towards surrounding tissues during phototherapy and steer the inflammation during the process of tissue regeneration. Accordingly, this work highlights the promising application of the photonic hydrogels in conquering refractory pathogen-invaded infection.

Sodium hyaluronate-g-2-((N-(6-aminohexyl)-4-methoxyphenyl)sulfonamido)-N-hydroxyacetamide with enhanced affinity towards MMP12 catalytic domain to be used as visco-supplement with increased degradation resistance

The present paper describes the functionalization of sodium hyaluronate (NaHA) with a small molecule (2-((N-(6-aminohexyl)-4-methoxyphenyl)sulfonamido)-N-hydroxyacetamide) (MMPI) having proven inhibitory activity against membrane metalloproteins involved in inflammatory processes (i.e. MMP12). The obtained derivative (HA-MMPI) demonstrated an increased resistance to the in-vitro degradation by hyaluronidase, viscoelastic properties close to those of healthy human synovial fluid, cytocompatibility towards human chondrocytes and nanomolar affinity towards MMP 12. Thus, HA-MMPI can be considered a good candidate as viscosupplement in the treatment of knee osteoarticular disease.

Synthetic PVA Osteochondral Implants for the Knee Joint: Mechanical Characteristics During Simulated Gait

BACKGROUND

Although polyvinyl alcohol (PVA) implants have been developed and used for the treatment of femoral osteochondral defects, their effect on joint contact mechanics during gait has not been assessed.

PURPOSE/HYPOTHESIS

The purpose was to quantify the contact mechanics during simulated gait of focal osteochondral femoral defects and synthetic PVA implants (10% and 20% by volume of PVA), with and without porous titanium (pTi) bases. It was hypothesized that PVA implants with a higher polymer content (and thus a higher modulus) combined with a pTi base would significantly improve defect-related knee joint contact mechanics.

STUDY DESIGN

Controlled laboratory study.

METHODS

Four cylindrical implants were manufactured: 10% PVA, 20% PVA, and 10% and 20% PVA disks mounted on a pTi base. Devices were implanted into 8 mm-diameter osteochondral defects created on the medial femoral condyles of 7 human cadaveric knees. Knees underwent simulated gait and contact stresses across the tibial plateau were recorded. Contact area, peak contact stress, the sum of stress in 3 regions of interest across the tibial plateau, and the distribution of stresses, as quantified by tracking the weighted center of contact stress throughout gait, were computed for all conditions.

RESULTS

An osteochondral defect caused a redistribution of contact stress across the plateau during simulated gait. Solid PVA implants did not improve contact mechanics, while the addition of a porous metal base led to significantly improved joint contact mechanics. Implants consisting of a 20% PVA disk mounted on a pTi base significantly improved the majority of contact mechanics parameters relative to the empty defect condition.

CONCLUSION

The information obtained using our cadaveric test system demonstrated the mechanical consequences of femoral focal osteochondral defects and provides biomechanical support to further pursue the efficacy of high-polymer-content PVA disks attached to a pTi base to improve contact mechanics.

CLINICAL RELEVANCE

As a range of solutions are explored for the treatment of osteochondral defects, our preclinical cadaveric testing model provides unique biomechanical evidence for the continued investigation of novel solutions for osteochondral defects.

In vitro study of chitosan-based multi-responsive hydrogels as drug release vehicles: a preclinical study

Systematic administration of painkillers and anti-inflammatory drugs is routinely employed to minimize pain and bodily disorders. Controlled drug delivery has the potential to improve the outcomes of disorders by providing sustained exposure to efficacious drug concentrations. Herein, we report the fabrication of multi-responsive hydrogels using reactive and functional polymers such as chitosan and polyvinyl pyrrolidone by varying the concentration of a cleavable crosslinker, tetraethyl orthosilicate. The swelling indices of the hydrogels were evaluated in distilled water, solutions with different pH values and different electrolytes. FTIR, WAXRD and TGA were conducted to investigate the structures, crystallinities and thermal stabilities of the prepared multi-responsive hydrogels, respectively. The ultimate tensile strength and elongations at break of the fabricated hydrogels were investigated to assess their mechanical stability. Optical microscopy, biodegradation, antimicrobial and cytotoxicity analyses were further carried out to verify the magnified crosslinked and porous structures, biodegradabilities, biocompatibilities and toxic behaviour of the as-prepared hydrogels, respectively. Drug release analysis was conducted to evaluate their release behaviour in PBS, SGF, SIF and electrolyte solutions. The overall results indicate the successful development of novel, non-toxic and sustained drug deliverable hydrogels, which can be considered as a paramount success towards the fabrication of controlled drug delivery systems.

Thixotropic PVA hydrogel enclosing a hydrophilic PVP core as nucleus pulposus substitute

A thixotropic polyvinyl alcohol (PVA) hydrogel, containing a hydrophilic poly-vinyl pyrrolidone (PVP) core, was obtained in order to develop a preformed 3D network able to maintain injectability. PVA was mixed with PVP in two different molar ratios (1:1 and 1:3) and chemically cross-linked using trisodium trimetaphosphate (STMP), which is able to react only with PVA component. A combination of Time of Flight- Secondary Ion Mass Spectrometry (ToF-SIMS), elemental analysis and UV spectroscopy permitted to determine both the cross-linking arm length and the crosslinking degree. Hydrogels were characterized in terms of swelling pressurization, rheological and mechanical behaviour. In particular, the viscoelastic behaviour of the hydrogel was analysed in shear and compression stress under dynamic conditions and compared with the performance of healthy human nucleus pulposus. In conclusion, the study demonstrated that the scaffold obtained mixing PVA and PVP in a molar ratio 1:1 can be considered a promising material to be utilised in the replacement of nucleus pulposus.

Biomaterials of PVA and PVP in medical and pharmaceutical applications: Perspectives and challenges

Poly(vinyl alcohol) (PVA) has attracted considerable research interest and is recognized among the largest volume of synthetic polymers that have been produced worldwide for almost one century. This is due to its exceptional properties which dictated its extensive use in a wide variety of applications, especially in medical and pharmaceutical fields. However, studies revealed that PVA-based biomaterials present some limitations that can restrict their use or performances. To overcome these limitations, various methods have been reported, among which blending with poly(vinylpyrrolidone) (PVP) showed promising results. Thus, our aim was to offer a systematic overview on the current state concerning the preparation, properties and various applications of biomaterials based on synergistic effect of mixtures between PVA and PVP. Future trends towards where the biomaterials research is headed were discussed, showing the promising opportunities that PVA and PVP can offer.

Chitosan–PVA monodisperse millimeter-sized spheres prepared by electrospraying reduce the thromboembolic risk in hemorrhage control

Chitosan–PVA monodisperse millimeter-sized spheres are efficient in hemorrhage control and also reduce the risk of thromboembolic complication.

The water-locking and cross-linking effects of graphene oxide on the load-bearing capacity of poly(vinyl alcohol) hydrogel

The GO sheets bound part of water molecules due to the abundant oxygen-containing functional groups on its surface and impede the water infiltration between the PVA molecules, improving the water-locking ability of the PVA/GO composites.

Physically crosslinked poly(vinyl alcohol)–carrageenan composite hydrogels: pore structure stability and cell adhesive ability

Poly(vinyl alcohol) (PVA)–carrageenan (CAR) composite hydrogels can reduce pore collapse during lyophilization and enhance cell adhesion in comparison to pure PVA hydrogels.

Freeze-Thawed Hybridized Preparation with Biomimetic Self-Assembly for a Polyvinyl Alcohol/Collagen Hydrogel Created for Meniscus Tissue Engineering

Freeze-thawed hybridized preparation and the biomimetic self-assembly technique were used to fabricate hydrogel as tissue engineered scaffolds for meniscus tissue. Because of the advantages of both techniques, they were hybridized together as an interesting preparation for hydrogel. Three molecular weights (high, medium, and low) of PVA were prepared in a biomimetic solution before formation into hydrogel by freeze-thawing. The most suitable molecular weight PVA for hydrogel formation was chosen to be mixed with collagen. PVA, PVA/collagen, and collagen were prepared in biomimetic solutions and freeze-thawed into hydrogels. The hydrogels were analyzed and characterized by FTIR, DSC, and SEM. FTIR characterization indicated that high molecular weight PVA formed molecular interaction better than the other molecular weights, and PVA molecules formed molecular interaction with collagen molecules via –OH and C=O groups. DSC characterization showed that the hybridized preparation of freeze-thawing and biomimetic self-assembly kept the characteristics of PVA and collagen. SEM analysis demonstrated that the morphological formation of PVA/collagen was hybridized during freeze-thawing and collagen self-assembly. The morphological structure was organized into a porous network structure. The porous structure showed a rough wall that was formed by the hybridized structure of the crystal domain dispersed in amorphous and collagen self-assembly.