Developing conductive hydrogels for biomedical applications

Self-healing injectable multifunctional hydrogels for intervertebral disc disease

Intervertebral disc degeneration (IVDD) is increasingly prevalent in aging societies and poses a significant health challenge. Due to the limited blood supply to the disc, oral medications and systemic treatments are often ineffective. Consequently, localized injection therapies, which deliver therapeutic agents directly to the degenerated disc, have emerged as more efficient. Self-healing injectable hydrogels are particularly promising due to their potential for minimally invasive delivery, precise implantation, and targeted drug release into hard-to-reach tissue sites, including those requiring prolonged healing. Their dynamic viscoelastic properties accurately replicate the mechanical environment of the natural nucleus pulposus, providing cells with an adaptive biomimetic microenvironment. This review will initially discuss the anatomy and pathophysiology of intervertebral discs, current treatments, and their limitations. Subsequently, we conduct bibliometric analysis to explore the research hotspots and trends in applying injectable hydrogel technology to treat IVDD. It will then explore the promising features of injectable hydrogels in biomedical applications such as drug, protein, cells and gene delivery, tissue engineering and regenerative medicine. We discuss the construction mechanisms of injectable hydrogels via physical interactions, chemical and biological crosslinkers, and discuss the selection of biomaterials and fabrication methods for developing novel hydrogels for IVD tissue engineering. The article concludes with future perspectives on the application of injectable hydrogels in this field.

Injectable bioresponsive bone adhesive hydrogels inhibit NLRP3 inflammasome on demand to accelerate diabetic fracture healing

Diabetes is associated with excessive inflammation, which negatively impacts the fracture healing process and delays bone repair. Previously, growing evidence indicated that activation of the nod-like receptor (NLR) family, such as nod-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome induces a vicious cycle of chronic low-grade inflammatory responses in diabetic fracture. Here, we describe the synthesis of a bone adhesive hydrogel that can be locally injected into the fracture site and releases a natural inhibitor of NLRP3 (rutin) in response to pathological cue reactive oxygen species activity (ROS). The hydrogel (denoted as RPO) was facilely formed by the cross-linking of rutin-functionalized gelatin, poly(vinyl alcohol), and oxidized starch based on the dynamic schiff base and boronate ester bond. Specifically, rutin is conjugated in the RPO hydrogel via a ROS linker and is released as the linker is cleaved by active ROS. In vitro studies demonstrate that RPO hydrogel effectively mitigates oxidative stress, alleviates mitochondrial dysfunction, and limits the overactivation of NLRP3 inflammasome in bone marrow derived macrophages, thereby promoting osteogenic differentiation of bone marrow mesenchymal stem cells. In a diabetic rat fracture model, RPO hydrogel significantly accelerates bone repair by modulating the inflammatory microenvironment. Our results demonstrate that local, on-demand NLRP3 inhibition for the treatment of diabetic fracture is achievable by using an injectable bioresponsive adhesive RPO hydrogel.

Piezoelectric dual-network tough hydrogel with on-demand thermal contraction and sonopiezoelectric effect for promoting infected-joint-skin-wound healing via FAK and AKT signaling pathways

The dynamic and whole stage management of infected wound healing throughout the entire repair process, including intelligent on-demand wound closure and the regulation of the transition from bactericidal to reparative phases, remains a major challenge. This study develops sonopiezoelectric-effect-mediated on-demand reactive-oxygen-species release by incorporating piezoelectric barium titanate modified with gold nanoparticles and a thermally responsive dual-network tough hydrogel dressing with a physical network structure based on ureidopyrimidinone-modified gelatin crosslinked by multiple hydrogen bonds, and with a chemical network structure based on N-isopropylacrylamide and methacryloyl gelatin formed via radical polymerization. This hydrogel exhibits temperature-sensitive softening, on-demand thermal contraction performance, high mechanical strength, good tissue adhesion, outstanding piezoelectricity, tunable sonopiezoelectric behavior, regulatable photothermal properties and desirable biocompatibility. The tunable sonopiezoelectric effect enables the hydrogel to eliminate wound bacteria in the short term, and effectively promote human fibroblast proliferation and migration over the long term. The hydrogel dressing actively contracts to close wound edges and further promotes the healing of MRSA-infected skin defects in the neck of mice by promoting fibroblast migration, enhancing collagen deposition and facilitating angiogenesis via up-regulating the FAK and AKT signaling pathways, providing a novel design strategy for developing dressings targeting chronic joint-skin wounds.

Self-Powered Thermoelectric Hydrogels Accelerate Wound Healing

Electrical stimulation (ES) serves as a biological cue that regulates critical cellular processes, including proliferation and migration, offering an effective approach to accelerating wound healing. Thermoelectrics, capable of generating electricity by exploiting the temperature difference between skin and the surrounding environment without external energy input, present a promising avenue for ES-based therapies. Herein, we developed Ag2Se@gelatin methacrylate (Ag2Se@GelMA) thermoelectric hydrogels with high room-temperature thermoelectric performance and employed them as self-powered ES devices for wound repair. Systematic in vivo and in vitro investigations elucidated their biological mechanisms for enhancing wound healing. Our findings reveal that the Ag2Se@GelMA thermoelectric hydrogels can significantly accelerate the wound closure by amplifying the endogenous electric field, thereby promoting cell proliferation, migration, and angiogenesis. Comprehensive in vitro experiments demonstrated that ES generated by the hydrogels activates voltage-gated calcium ion channels, elevating intracellular Ca2+ levels and enhancing mitochondrial functions through the Ca2+/CaMKKβ/AMPK/Nrf2 pathway. This cascade improves mitochondrial dynamics and angiogenesis, thereby accelerating tissue regeneration. The newly developed Ag2Se@GelMA thermoelectric hydrogels represent a marked progress in wound dressing technology with the potential to improve clinical strategies in tissue engineering and regenerative medicine.

Biomaterial-based drug delivery systems in the treatment of inner ear disorders

Inner ear disorders are among the predominant etiology of hearing loss. The blood-labyrinth barrier limits the ability of drugs to attain pharmacologically effective concentrations within the inner ear; consequently, delivering drugs systemically is insufficient for effectively treating inner ear disorders. Hence, it is imperative to create efficient, minimal or non-invasive methods for administering drugs to the inner ear. However, the development of such a system is hindered by three main factors: anatomical unavailability, the lack of sustained drug delivery, and individual variability. Advances in biomaterials technology have created new opportunities for overcoming existing barriers, offering great hope for the effective treatment of inner ear disorders. Hydrogel- and nanoparticle-based drug delivery systems can carry drugs to targeted designated anatomical locations in the inner ear for long-term, sustained release. Furthermore, a range of devices, including microneedles, micropumps, and cochlear implants, when paired with biomaterials, enhance the delivery of drugs to the inner ear, making the treatment of inner ear disorders more effective. Therefore, biomaterial-based drug delivery systems offer the possibility for extensive clinical uses and promise to restore hearing to millions of patients with inner ear disorders.

Orally Administered ZnxCeyO2/Se Hydrogel with Effective Antioxidant Activity for Treating Inflammatory Bowel Disease by Inhibiting Ferroptosis

Oxidative stress leads to intestinal barrier damage, which induces immune responses to occur and further promotes oxidative stress exacerbating inflammatory bowel disease (IBD). In this work, the multifunctional ZnxCeyO2/Se (ZCSO) nanozyme wrapped with acid-resistant calcium alginate hydrogel designed for oral administration is prepared. The ZCSO nanozyme can promote the activation of the Nrf2 oxidative stress pathway, then significantly improve the efficiency of scavenging reactive oxygen species (ROS) and up-regulate the protein expression of glutathione peroxidase 4 (GPx4), which is closely related to the inhibition of ferroptosis. In addition, the ZCSO nanozyme inhibiting the growth of some pathogenic bacteria proliferating due to oxidative stress shows a positive regulation of the intestinal flora and reduces the secretion of pro-inflammatory factors and the levels of inflammatory macrophages, achieving the significant preventive and delayed therapeutic effect of colitis mice. Consequently, the distinctive properties of ZCSO nanozyme render it a promising candidate for the treatment of IBD by effectively scavenging ROS, thereby interrupting the detrimental cycle between oxidative stress and immune response, ultimately promoting the proliferation of epithelial cells to reestablish the integrity of the intestinal mucosal barrier.

Polymer Applied in Hydrogel Wound Dressing for Wound Healing: Modification/Functionalization Method and Design Strategies

Hydrogel wound dressings have emerged as a promising solution for wound healing due to their excellent mechanical and biochemical properties. Over recent years, there has been significant progress in expanding the variety of raw materials used for hydrogel formulation along with the development of advanced modification techniques and design approaches that enhance their performance. However, a comprehensive review encompassing diverse polymer modification strategies and design innovations for hydrogel dressings is still lacking in the literature. This review summarizes the use of natural polymers (e.g., chitosan, gelatin, sodium alginate, hyaluronic acid, and dextran) and synthetic polymers (e.g., poly(vinyl alcohol), polyethylene glycol, Pluronic F-127, poly(N-isopropylacrylamide), polyacrylamide, and polypeptides) in hydrogel wound dressings. We further explore the advantages and limitations of these polymers and discuss various modification strategies, including cationic modification, oxidative modification, double-bond modification, catechol modification, etc. The review also addresses design principles and synthesis methods, aligning polymer modifications with specific requirements in wound healing. Finally, we discuss future challenges and opportunities in the development of advanced hydrogel-based wound dressings.

Preparation of an antibacterial, injectable, thermosensitive, and physically cross-linked hemostatic hydrogel based on quaternized linetype poly(N-isopropylacrylamide)

Bleeding and wound infection are two significant potential risks to life and health. While antibacterial hemostatic hydrogels can meet the requirements for hemostasis and the prevention of wound infections, the inclusion of antibacterial agents inevitably complicates the regulation of interactions between components, making it difficult to synergistically control the mechanical and antibacterial properties of the hydrogels, which limits the overall hydrogel performance. In this study, we propose the use of linear poly(N-isopropylacrylamide) (L-P-(C6H15N+)) with an antibacterial quaternary ammonium end-group for preparing hydrogels, rather than conventionally adding antibacterial agents. An injectable, highly antibacterial and wet-adhesive double-network hemostatic hydrogel was constructed using L-P-(C6H15N+), gelatin (G), and hyaluronic acid (HA). The comprehensive properties of the hydrogel could be adjusted through changing the molecular weight of the L-P-(C6H15N+) and the end-group effects. The G/HA/L-P-(C6H15N+) hydrogel demonstrated a gel time of 12.2-14 s, an adhesion strength of 26.9 ± 2.0 kPa and a burst pressure of 264 ± 20 mmHg. It also exhibited strong antibacterial activity against E. coli (93 ± 2.7%) and S. aureus (97 ± 3.2%), with satisfactory biocompatibility. Additionally, the hydrogel demonstrated good blood clotting ability in vitro and achieved rapid hemostasis (<15 s) in vivo. This work offers a simple and efficient strategy to fabricate high-performance smart antibacterial hemostatic hydrogels.

Reduce electrical overload via threaded Chinese acupuncture in nerve electrical therapy

Bioelectrical stimulation is a powerful technique used to promote tissue regeneration, but it can be hindered by an "electrical overload" phenomenon in the core region of stimulation. We develop a threaded microneedle electrode system that protects against "electrical overload" by delivering medicinal hydrogel microspheres into the core regions. The threaded needle body is coated with polydopamine and chitosan to enhance the adhesion of microspheres, which are loaded into the threaded grooves, allowing for their stereoscopic release in the core regions. After the electrode is inserted, the microspheres can be delivered three-dimensionally through physical swelling and the shear-thinning effect of chitosan, mitigating the electrical damage. Microspheres are designed to release alkylated vitamin B12 and vitamin E, providing antioxidant and cell protection effects upon in-situ activation, reducing reactive oxygen species (ROS) by 72.8 % and cell death by 59.5 %. In the model of peripheral nerve injury, the electrode system improves the overall antioxidant capacity by 78.5 % and protects the surrounding cells. Additionally, it leads to an improved nerve conduction velocity ratio of 41.9 % and sciatic nerve function index of 12.1 %, indicating enhanced neuroregeneration. The threaded microneedle electrode system offers a promising approach for nerve repair by inhibiting "electrical overload", potentially improving outcomes for tissue regeneration.

Injectable hydrogel regulates immune infiltration through physical and chemical synergy in the treatment of steroid-induced osteonecrosis of the femoral head

The incidence of steroid-induced osteonecrosis of the femoral head (SONFH) is increasing annually; however, the underlying pathological mechanism remains unclear, which is an obstacle to its effective treatment. The negative effect of immune infiltration on the physiological activity of focal stem cells is one potential mechanism that has attracted attention. It is difficult to simulate the complex regulation of the interaction system between immune cells and stem cells using a single regulation method. In this study, we demonstrated that the immune infiltration of T helper 17 (Th17) cells plays an important role in the progression of SONFH. Based on this finding, we developed an injectable hydrogel system with both physical and chemical synergistic regulatory properties to enhance the activity of stem cells using electrical stimulation. This treatment was designed to prevent the infiltration of Th17 cells by regulating the physiological function of stem cells and blocking the negative effect of Th17 cells on stem cells pharmacologically. Thus, the dual synergistic regulation of immune infiltration at the lesion site of SONFH enhanced the physiological activity and function of the stem cells, thereby improving the therapeutic effect of SONFH. This hydrogel system provides insight for the future development of multifactorial regulatory systems and provides a strategy for the treatment of SONFH.

An anti-inflammatory and anti-fibrotic Janus hydrogel for preventing postoperative peritoneal adhesion

Postoperative peritoneal adhesion (PPA) is pathological tissue hyperplasia between surgical wounds and nearby organs. Currently, traditional double-sided bioadhesives are limited in preventing PPA due to the indiscriminate adhesive properties and the poor interaction with wet tissues. Herein, we developed a Janus hydrogel, named PAA-Cos, by using the polycationic carbohydrate polymer of chitooligosaccharide (Cos) and the polyanionic polymer of polyacrylic acid (PAA). The adhesive layer of Janus hydrogels could adhere to wet tissue tightly due to surfaces composed of carboxyls, and the positively charged biomaterial (Cos) neutralized carboxyls on one side of PAA hydrogel to form Janus hydrogels. Moreover, PAA-Cos can further load with ligustrazine hydrochloride (Ligu), a pharmaceutical compound with anti-inflammatory and anti-fibrotic effects, finally obtaining PAA-Cos@Ligu. After the application of PAA-Cos@Ligu on the surgical trauma, the bottom surface can adhere to wet tissues robustly to restore the wound, while the top surface acts as a physical barrier with antiadhesive effects to avoid PPA. PAA-Cos@Ligu also exhibited anti-inflammatory effects by promoting M2 macrophage polarization, inhibiting the myofibroblast-like differentiation of peritoneal mesothelial cells, and blocking the TGF-β/Smad2/3 signaling pathway to hinder collagen deposition. Our findings suggest that PAA-Cos@Ligu has great potential as an anti-adhesion candidate with biocompatibility and ease of preparation.

Recombinant human collagen hydrogels with different stem cell-derived exosomes encapsulation for wound treatment

Exosomes-loaded hydrogels have potential value in wound treatment. Current studies focus on improving hydrogels' biocompatibility and optimizing different stem cell-derived exosomes for better therapeutic effect. Herein, we present a novel biocompatible recombinant human collagen (RHC) hydrogel loading with different MSCs-derived exosomes for promoting wound healing. We modify the RHC with methacrylate anhydride (MA) at optimal concentration, generating collagen hydrogel (RHCMA) with ideal physiochemical properties for exosome delivery (MSC-exos@RHCMA). Exosomes derived from human adipose-derived MSCs (ADSC-exos), bone marrow-derived MSCs (BMSC-exos) and umbilical cord MSCs (ucMSC-exos) are harvested from the culture supernatants and are loaded into RHCMA, respectively. These three hydrogel systems exhibit desired sustained release features, and can significantly improve cell proliferation and migration. In addition, these MSC-exos@RHCMAs show excellent therapeutic performance in treating the wounds of rats. Notably, we have demonstrated that the healing effect occurs best under the treatment of ucMSC-exos@RHCMA, following inflammatory resolution, angiogenesis, and collagen formation. These results would supply important value for the clinical application of MSC-exos in wound treatment in the future.

Developing 3D bioprinting for organs-on-chips

Organs-on-chips (OoCs) have significantly advanced biomedical research by precisely reconstructing human microphysiological systems with biomimetic functions. However, achieving greater structural complexity of cell cultures on-chip for enhanced biological mimicry remains a challenge. To overcome these challenges, 3D bioprinting techniques can be used in directly building complex 3D cultures on chips, facilitating the in vitro engineering of organ-level models. Herein, we review the distinctive features of OoCs, along with the technical and biological challenges associated with replicating complex organ structures. We discuss recent bioprinting innovations that simplify the fabrication of OoCs while increasing their architectural complexity, leading to breakthroughs in the field and enabling the investigation of previously inaccessible biological problems. We highlight the challenges for the development of 3D bioprinted OoCs, concluding with a perspective on future directions aimed at facilitating their clinical translation.

Smart hydrogels for rapid wound repair: Chitosan-PVP matrices empowered by bimetallic MOF nanocages

In wound treatment, sustainable and effective dressings are crucial for rapid healing without scarring. Antimicrobial transparent hydrogel dressings were fabricated by grafting chitosan with polyvinyl pyrrolidone and impregnating it with zinc or zinc-silver metal-organic framework nanocages (30-50 nm). Characterization confirmed the hydrogels' excellent physical and chemical integrity. Comprehensive antibacterial, antifungal, and ion-release evaluations validated their efficacy, demonstrating remarkable results. These dressings also promoted a moisture-balanced environment ideal for wound healing. Comprehensive evaluations of these hydrogel dressings' antibacterial, antifungal, and ion-release properties confirmed their efficacy, demonstrating remarkable results. The dressings also promoted a moisture-balanced environment optimal for wound healing. Cytotoxicity tests on skin cells indicated that the hydrogels were safe and enhanced cell proliferation. Notably, CS/PVP hydrogels with bimetallic nanocages (CS/PVP4) achieved up to 69 % healing within 7 days. This rapid healing occurred due to the reduction of inflammation and IL-1 content in the dermis; the downregulation of MMP9 halted the breakdown of the extracellular matrix (ECM); the upregulation of TGF accelerated cell growth and raised the levels of collagen 1 and -SMA in the ECM. These findings suggest that the developed hydrogel dressings will provide sustainable wound healing, thereby increasing patient satisfaction.

Slide-Ring Structured Stress-Electric Coupling Hydrogel Microspheres for Low-Loss Transduction Between Tissues

High transductive loss at tissue injury sites impedes repair. The high dissipation characteristics in the electromechanical conversion of piezoelectric biomaterials pose a challenge. Therefore, supramolecular engineering and microfluidic technology is utilized to introduce slide-ring polyrotaxane and conductive polypyrrole to construct stress-electric coupling hydrogel microspheres. The molecular slippage mechanism of slide-ring structure stores and releases mechanical energy, reducing mechanical loss, the piezoelectric barium titanate enables stress-electricity conversion, and conjugated π-electron movement in conductive network improves the internal electron transfer efficiency of microspheres, thereby reducing the loss in stress-electricity conversion for the first time. Compared to traditional piezoelectric hydrogel microspheres, the stress-electric coupling efficiency of low-dissipation microspheres increased by 2.3 times, and the energy dissipation decreased to 43%. At cellular level, electrical signals generated by the microspheres triggered Ca2+ influx into stem cells and upregulated the cAMP signaling pathways, promoting chondrogenic differentiation. Enhanced electrical signals induced macrophage polarization to the M2 phenotype, reshaping inflammation and promoting tissue repair. In vivo, the low-dissipation microspheres restored low-loss transduction between tissues, alleviated cartilage damage, improved behavioral outcomes, and promoted the treatment of osteoarthritis in rats. Therefore, this study proposes a new strategy for restoring low-loss transduction between tissues, particularly in mechanically sensitive tissues.

Enhanced hydrogel loading of quercetin-loaded hollow mesoporous cerium dioxide nanoparticles for skin flap survival

Flap techniques are indispensable in modern surgery because of their role in repairing tissue defects and restoring function. Ischemia-reperfusion and oxidative stress-induced injuries are the main causes of flap failure. Oxidative stress exacerbates cell damage through the accumulation of reactive oxygen species (ROS), thereby affecting flap function and survival. Effective management of these factors is essential for improving flap survival and post-operative recovery. In this study, we utilized hollow mesoporous cerium dioxide nanoparticles loaded with quercetin, which were later loaded into a light-cured double cross-linked hydrogel (HQu@BC) and injected into the flap site to activate macrophage reprogramming to maintain local ROS homeostasis and reduce inflammation. Quercetin scavenges ROS and reduces mitochondrial oxidative stress due to its intrinsic reducing structures such as catechols, carbon-carbon double bonds, and hydroxyl synergistic mesoporous cerium dioxide nanoparticles, and inhibits inflammation by suppressing M1 macrophage polarization. This system continuously regulates ROS levels, kills bacteria and ultimately reduces inflammation, thereby creating a favorable microenvironment for flap survival. This innovative injectable composite nanoparticle hydrogel material has anti-inflammatory, antioxidant, antimicrobial, and healing-promoting properties, providing a new approach to improving the success of flap surgery.

Dexamethasone loaded DNA scavenger nanogel for systemic lupus erythematosus treatment

Lupus nephritis (LN) poses a severe risk for individuals with systemic lupus erythematosus (SLE), prompting extensive research into targeted delivery systems capable of modulating immune responses and clearing cell-free DNA (cfDNA). Here, we propose a novel renal homing nanogel that acts as a cfDNA scavenger and a dexamethasone (DXM) delivery carrier for LN treatment. Based on the generation 3 polylysine dendrimers, the created cationic nanogels (G3DSP) exhibit minimal toxicity and outstanding DXM loading efficiency. Our studies confirm that these nanogels can competitively bind with anionic cfDNA in vitro, leading to the suppression of toll-like receptor 9 (TLR9) activation. When administered systemically to MRL/lpr mice, the nanogels preferentially localize to and are retained in the inflamed kidneys, releasing their payload in response to reactive oxygen species (ROS), therefore effectively ameliorating SLE symptoms. Consequently, G3DSP nanogels emerge as a promising effective combined therapy for LN, minimizing cfDNA accumulation in vital organs and delivering immunomodulatory benefits through DXM.

Emerging Functional Porous Scaffolds for Liver Tissue Engineering

Liver tissue engineering holds promising in synthesizing or regenerating livers, while the design of functional scaffold remains a challenge. Owing to the intricate simulation of extracellular matrix structure and performance, porous scaffolds have demonstrated advantages in creating liver microstructures and sustaining liver functions. Currently, various methods and processes have been employed to fabricate porous scaffolds, manipulating the properties and morphologies of materials to confer them with unique supportive functions. Additionally, scaffolds must also facilitate tissue growth and deliver cells, possessing therapeutic or regenerative effects. In this review, it is initially outline typical procedures for fabricating porous scaffolds and showcase various morphologies of microstructures. Subsequently, it is delved into the forms of cell loading in porous scaffolds, including scaffold-based, scaffold-free, and synergetic or bioassembly approaches. Lastly, the utilization of porous scaffolds in liver diseases, offering significant insights and future implications for liver regeneration research in tissue engineering is explored.

Protonated-chitosan sponge with procoagulation activity for hemostasis in coagulopathy

Hemostatic materials are essential for managing acute bleeding in medical settings. Chitosan (CS) shows promise in hemostasis but its underlying mechanism remains incompletely understood. We unexpectedly discovered that certain protonated-chitosan (PCS) rapidly assembled plasma proteins to form protein membrane (PM) upon contact with platelet-poor plasma (PPP). We hypothesized that the novel observation was intricately related to the procoagulant effect of chitosan. Herein, the study aimed to elucidate the conditions necessary and mechanism for PM formation, identify the proteins within the PM and PCS's procoagulant action at the molecule levels. We confirmed that the amount of -NH3 + groups (>4.9 mmol/g) on PCS molecules played a crucial role in promoting coagulation. The -NH3 + group interacted with blood's multiple active components to exert hemostatic effects: assembling plasma proteins including coagulation factors such as FII, FV, FX, activating blood cells and promoting the secretion of coagulation-related substances (FV, ADP, etc) by platelets. Notably, the hemostatic mechanism can be extended to protonated-chitosan derivatives like quaternized, alkylated, and catechol-chitosan. In the blood clotting index (BCI) experiment, compared to other groups, PCS95 achieved the lowest BCI value (∼6 %) within 30 s. Protonated-chitosan exhibited excellent biocompatibility and antibacterial properties, with PCS95 demonstrating inhibition effectiveness of over 95 % against Escherichia coli (E.coil) and Staphylococcus aureus (S. aureus). Moreover, PCS performed enhanced hemostatic effectiveness over chitosan-based commercially agents (Celox™ and ChitoGauze®XR) in diverse bleeding models. In particular, PCS95 reduced bleeding time by 70 % in rabbit models of coagulopathy. Overall, this study investigated the coagulation mechanism of materials at the molecular level, paving the way for innovative approaches in designing new hemostatic materials.

Hydrogel-based therapeutic strategies for spinal cord injury repair: Recent advances and future prospects

Spinal cord injury (SCI) is a debilitating condition that can result in significant functional impairment and loss of quality of life. There is a growing interest in developing new therapies for SCI, and hydrogel-based multimodal therapeutic strategies have emerged as a promising approach. They offer several advantages for SCI repair, including biocompatibility, tunable mechanical properties, low immunogenicity, and the ability to deliver therapeutic agents. This article provides an overview of the recent advances in hydrogel-based therapy strategies for SCI repair, particularly within the past three years. We summarize the SCI hydrogels with varied characteristics such as phase-change hydrogels, self-healing hydrogel, oriented fibers hydrogel, and self-assembled microspheres hydrogel, as well as different functional hydrogels such as conductive hydrogels, stimuli-responsive hydrogels, adhesive hydrogel, antioxidant hydrogel, sustained-release hydrogel, etc. The composition, preparation, and therapeutic effect of these hydrogels are briefly discussed and comprehensively evaluated. In the end, the future development of hydrogels in SCI repair is prospected to inspire more researchers to invest in this promising field.

Collagen as the extracellular matrix biomaterials in the arena of medical sciences

Collagen is a multipurpose material that has several applications in the health care, dental care, and pharmaceutical industries. Crosslinked compacted solids or lattice-like gels can be made from collagen. Biocompatibility, biodegradability, and wound-healing properties make collagen a popular scaffold material for cardiovascular, dentistry, and bone tissue engineering. Due to its essential role in the control of several of these processes, collagen has been employed as a wound-healing adjunct. It forms a major component of the extracellular matrix and regulates wound healing in its fibrillar or soluble forms. Collagen supports cardiovascular and other soft tissues. Oral wounds have been dressed with resorbable forms of collagen for closure of graft and extraction sites, and to aid healing. This present review is concentrated on the use of collagen in bone regeneration, wound healing, cardiovascular tissue engineering, and dentistry.

Introductory Review of Soft Implantable Bioelectronics Using Conductive and Functional Hydrogels and Hydrogel Nanocomposites

Interfaces between implantable bioelectrodes and tissues provide critical insights into the biological and pathological conditions of targeted organs, aiding diagnosis and treatment. While conventional bioelectronics, made from rigid materials like metals and silicon, have been essential for recording signals and delivering electric stimulation, they face limitations due to the mechanical mismatch between rigid devices and soft tissues. Recently, focus has shifted toward soft conductive materials, such as conductive hydrogels and hydrogel nanocomposites, known for their tissue-like softness, biocompatibility, and potential for functionalization. This review introduces these materials and provides an overview of recent advances in soft hydrogel nanocomposites for implantable electronics. It covers material strategies for conductive hydrogels, including both intrinsically conductive hydrogels and hydrogel nanocomposites, and explores key functionalization techniques like biodegradation, bioadhesiveness, injectability, and self-healing. Practical applications of these materials in implantable electronics are also highlighted, showcasing their effectiveness in real-world scenarios. Finally, we discuss emerging technologies and future needs for chronically implantable bioelectronics, offering insights into the evolving landscape of this field.

Osteoblastic Cell Sheet Engineering Using P(VCL-HEMA)-Based Thermosensitive Hydrogels Doped with pVCL@Icariin Nanoparticles Obtained with Supercritical CO2-SAS

New clinical strategies for treating severe bone and cartilage injuries are required, especially for use in combination with implant procedures. For this purpose, p(VCL-co-HEMA) thermosensitive hydrogels have been activated with icariin-loaded nanoparticles to be used as bone-cell-harvesting platforms. Supercritical CO2-SAS technology has been applied to encapsulate icariin, a small molecule that is involved in osteoblastic differentiation. Thus, physical-chemical analysis, including swelling and transmittance, showed the impact of HEMA groups in hydrogel composition. Moreover, icariin (ICA) release from p(VCL-co-HEMA) platforms, including pVCL@ICA nanoparticles, has been studied to evaluate their efficacy in relevant conditions. Finally, the thermosensitive hydrogels' cell compatibility, transplant efficiency, and bone differentiation capacity were tested. This study identifies the optimal formulations for icariin-activated hydrogels for both control and HEMA formulations. Using this technique, osteoblastic sheets that were rich in collagen type I were successfully transplanted and recultivated, maintaining an optimal extracellular matrix (ECM) composition. These findings suggest a new cell-sheet-based therapy for bone regeneration purposes using customized and NP-activated pVCL-based cell platforms.