Tailoring the Swelling-Shrinkable Behavior of Hydrogels for Biomedical Applications

Pectin-chitosan hydrogels with modified properties for the encapsulation of strawberry phenolic compounds

Pectin-chitosan hydrogels with blends of low (50-190 kDa) and medium (310-395 KDa) molecular weight (MW) chitosan (LC and MC, respectively) were developed, and their characteristics were investigated before and after the encapsulation of an aqueous strawberry extract. The pectin to total chitosan mass ratio, the composition of the strawberry extract and the MW of chitosan greatly affected the interactions between pectin and chitosan at different pH values. More specifically, blends of low and medium MW chitosan improved the stability of the strawberry-gels in acidic conditions compared to their corresponding MC-gels, showed better flow and texture profiles, as well as slower release of phenolic compounds during in vitro digestion compared to the only stable LC-gel. Therefore, by manipulating the length range of chitosan chains would allow the formation of pectin-chitosan hydrogels with improved properties for the development of functional food products.

Multifunctional poloxamer-based thermo-responsive hydrogel loaded with human lactoferricin niosomes: In vitro study on anti-bacterial activity, accelerate wound healing, and anti-inflammation

Chronic wound infections are attributed to delayed tissue repair, which remains a major clinical challenge in long-term health care. Particularly, infections with antibiotic resistance have more serious effects on health, often resulting in unsuccessful treatments. Thus, antimicrobial peptide (AMP)-based therapy holds promise as a potential therapeutic approach to overcoming drug resistance. Conventional wound dressing is a passive strategy for wound care that is not capable of eradicating pathogens and promoting tissue repair. In this study, we aim to construct an advanced wound dressing; a thermo-responsive hydrogel incorporated with lactoferricin (Lfcin) niosome (Lfcin-Nio/hydrogel) for bacterial pathogen treatment. The Lfcin-loaded niosome (Lfcin-Nio) has a particle size of 396.91 ± 20.96 nm, 0.38 ± 0.01 of PdI, -10.5 ± 0.3 mV of ζ potential, and 72.30 ± 7.05 % Lfcin entrapment efficiency. Lfcin-Nio exhibited broad antibacterial activity on both drug-susceptible and drug-resistant strains, and also on bacteria residing in the biofilm matrix. The Lfcin-Nio/hydrogel was fabricated from 0.5 % w/v poloxamer 188-20 % w/v poloxamer 407, and supplemented with Lfcin-Nio and epidermal growth factor (EGF). The physical properties of Lfcin-Nio/hydrogels showed elasticity, swelling ability, and strong injectability with responsiveness to 33-37 °C temperatures. The biological properties of Lfcin-Nio/hydrogels exhibited a bactericidal effect against drug-resistant strains of S. aureus and P. aeruginosa, and showed less toxicity to the human skin fibroblast. It also promoted the healing of scratches by 55 % within 6 h, compared to the wound closure rate of 20 % in the cell control. The inflammatory response of the Lfcin-Nio/hydrogel-treated cells was reduced via suppression of IL-1β and COX-2 mRNA expressions. From this study, Lfcin-Nio/hydrogels can be suggested as a modern wound dressing that possesses multifunctional and beneficial properties for the management of chronic wound infections.

Design of nanosystems for melanoma treatment

Melanoma is a prevalent and concerning form of skin cancer affecting millions of individuals worldwide. Unfortunately, traditional treatments can be invasive and painful, prompting the need for alternative therapies with improved efficacy and patient outcomes. Nanosystems offer a promising solution to these obstacles through the rational design of nanoparticles (NPs) which are structured into nanocomposite forms, offering efficient approaches to cancer treatment procedures. A range of NPs consisting of polymeric, metallic and metal oxide, carbon-based, and virus-like NPs have been studied for their potential in treating skin cancer. This review summarizes the latest developments in functional nanosystems aimed at enhancing melanoma treatment. The fundamentals of these nanosystems, including NPs and the creation of various functional nanosystem types, facilitating melanoma treatment are introduced. Then, the advances in the applications of functional nanosystems for melanoma treatment are summarized, outlining both their benefits and the challenges encountered in implementing nanosystem therapies.

Alginate-based hydrogels mediated biomedical applications: A review

With the development in the field of biomaterials, research on alternative biocompatible materials has been initiated, and alginate in polysaccharides has become one of the research hotspots due to its advantages of biocompatibility, biodegradability and low cost. In recent years, with the further understanding of microscopic molecular structure and properties of alginate, various physicochemical methods of cross-linking strategies, as well as organic and inorganic materials, have led to the development of different properties of alginate hydrogels for greatly expanded applications. In view of the potential application prospects of alginate-based hydrogels, this paper reviews the properties and preparation of alginate-based hydrogels and their major achievements in delivery carrier, dressings, tissue engineering and other applications are also summarized. In addition, the combination of alginate-based hydrogel and new technology such as 3D printing are also involved, which will contribute to further research and exploration.

Deformation-Resistant Underwater Adhesion in a Wide Salinity Range

Conventional adhesives experience reduced adhesion when exposed to aqueous environments. The development of underwater adhesives capable of forming strong and durable bonds across various wet substrates is crucial in biomedical and engineering domains. Nonetheless, limited emphasis placed on retaining high adhesion strengths in different saline environments, addressing challenges such as elevated osmotic pressure and spontaneous dimensional alterations. Herein, a series of ionogel-based underwater adhesives are developed using a copolymerization approach that incorporates "dynamic complementary cross-linking" networks. Synergistic engineering of building blocks, cross-linking networks, pendant groups and counterions within ionogels ensures their adhesion and cohesion in brine spanning a wide salinity range. A high adhesion strength of ≈3.6 MPa is attained in freshwater. Gratifyingly, steady adhesion strengths exceeding 3.3 MPa are retained in hypersaline solutions with salinity ranging from 50 to 200 g kg-1, delivering one of the best-performing underwater adhesives suitable for diverse saline solutions. A combination of outstanding durability, reliability, deformation resistance, salt tolerance, and self-healing properties showcases the "self-contained" underwater adhesion. This study shines light on the facile fabrication of catechol-free ionogel-based adhesives, not merely boosting adhesion strengths in freshwater, but also broadening their applicability across various saline environments.

Anti-inflammatory dressing based on hyaluronic acid and hydroxyethyl starch for wound healing

Eliminating persistent inflammation and choosing dressings that provide the best healing environment is key to promoting wound healing. Dynamic and reversible hydrogels have attracted much attention because of their capacity to adapt to irregular wound surfaces. Herein, oxidized hydroxyethyl starch (OHES) and hyaluronic acid (HA-ADH) were crosslinked via the dynamic acylhydrazone bond to form an anti-inflammatory function hydrogel (HA-ADH/OHES@XT) that could release xanthatin (XT) slowly. The HA-ADH/OHES hydrogels showed an appropriate gelation time, notable water-retaining capacity, self-healing, suitable biodegradability, and good biocompatibility for wound healing applications. In vivo experiments demonstrated that HA-ADH/OHES@XT hydrogels promoted tissue regeneration and wound healing at a rate of approximately 89.1 % on day 20 by reducing inflammation, increasing collagen deposition, and promoting re-epithelialization, indicating their great potential as a wound dressing.

Drug conjugates crosslinked bioresponsive hydrogel for combination therapy of diabetic wound

Basic fibroblast growth factor (bFGF) has proved to be effective for wound healing, yet its effectiveness is extremely retarded in diabetic wounds due to the severe oxidative stress in wound beds. To solve this issue, herein a novel combination therapy of bFGF and N-acetylcysteine (NAC, antioxidant) was devised for improved diabetic wound repair. To avoid rapid loss of both drugs in the wound beds, a bioresponsive hydrogel (bFGF-HSPP-NAC) was engineered by incorporating bFGF and NAC into polymer-drug conjugates (HSPP) via thiol-disulfide exchange reactions. In response to oxidative stress (e.g., reactive oxygen species), the disulfide bonds (SS) within the hydrogel are broken into thiol groups (-S-H), thereby promoting hydrogel degradation and enabling controlled drug release. Initially, NAC is released to scavenge free radicals and ameliorate oxidative damage. Subsequently, bFGF is released to expedite tissue regeneration. This combinatorial strategy is tailored to the specific characteristics of the wound microenvironment at various stages of diabetic wound healing, thereby achieving therapeutic efficacy. The results indicate that the bFGF-HSPP-NAC hydrogel markedly enhances re-epithelialization, collagen deposition, hair follicle regeneration, and neovascularization. In conclusion, the bioresponsive bFGF-HSPP-NAC hydrogel demonstrates significant potential for application in combinatorial therapeutic approaches for diabetic wound healing.

Mechanical and Dimensional Stability of Gelatin-Based Hydrogels Through 3D Printing-Facilitated Confined Space Assembly

Hydrogels have emerged as promising biomaterials for tissue regeneration; yet, their inherent swelling can cause deformation and reduced mechanical properties, posing challenges for practical applications in biomedical engineering. Traditional methods to reduce hydrogel swelling often involve complex synthesis procedures with limited flexibility. Inspired by nature's efficient designs, we present here the approach to improve hydrogel performance using 3D printing-assisted microstructure engineering. By utilizing polymerization-induced phase separation of hydrogel from copolymerization of gelatin methacrylate and hydroxyethyl methacrylate (poly(GelMA-co-HEMA)) in the confined space during vat photopolymerization (VPP) 3D printing, we replicate the cuttlebone-like microstructure of hydrogels with enhanced mechanical properties and swelling resistance. We demonstrate here a 4-fold increase in elastic modulus compared to bulk polymerization of poly(GelMA-co-HEMA), together with improved mechanical and dimensional stability. This method offers promising opportunities for practical biomedical and tissue engineering applications, overcoming previous limitations in the design and performance.

Alginate/GelMA microparticles via oil-free interface shearing for untethered magnetic microbots

Microrobots hold broad application prospects in the field of precision medicine, such as intravenous drug injection, tumor resection, opening blood vessels and imaging during abdominal surgery. However, the rapid and controllable preparation of biocompatible hydrogel microparticles still poses challenges. This study proposes the one-step direct acquisition of biocompatible sodium alginate and gelatin methacrylate (GelMA) hydrogel microparticles using an oil-free aqueous solution, ensuring production with a controllable generation frequency. An adaptive interface shearing platform is established to fabricate alginate/GelMA microparticles using a mixture of the hydrogel, photoinitiator, and Fe3O4 nanoparticles (NPs). By adjusting the static magnetic field intensity (Bs), vibration frequency, and flow rate (Q) of the dispersed phase, the size and morphology of the hydrogel microparticles can be controlled. These hydrogel microparticle robots exhibit magnetic responsiveness, demonstrating precise rotating and rolling movements under the influence of an externally rotating magnetic field (RMF). Moreover, hydrogel microparticle robots with a specific critical frequency (Cf) can be customized by adjusting the Bs and the concentration of Fe3O4 NPs. The directional in situ untethered motion of the hydrogel microparticle robots can be successfully realized and accurately controlled in the climbing over obstacles and in vitro experiments of animals, respectively. This versatile and fully biodegradable microrobot has the potential to precisely control movement to bone tissue and the natural cavity of the human body, as well as drug delivery.

Shear-Induced Cycloreversion Leading to Shear-Thinning and Autonomous Self-Healing in an Injectable, Shape-Holding Collagen Hydrogel

In vivo injectable extracellular matrix (ECM) derived hydrogels that are suitable for cell encapsulation have always been the holy grail in tissue engineering. Nevertheless, these hydrogels still fall short today of meeting three crucial criteria: (a) flexibility on the injectability time window, (b) autonomous self-healing of the injected hydrogel, and (c) shape-retention under aqueous conditions. Here we report the development of a collagen-based injectable hydrogel, cross-linked by cycloaddition reaction between furan and maleimide groups, that (a) is injectable up to 48 h after preparation, (b) can undergo complete autonomous self-healing after injection, (c) can retain its shape and size over several years when stored in the buffer, (d) can be degraded within hours when treated with collagenase, (e) is biocompatible as demonstrated by in vitro cell-culture, and (f) is completely resorbable in vivo when implanted subcutaneously in rats without causing any inflammation.

Spectroscopic and Thermal Characterisation of Interpenetrating Hydrogel Networks (IHNs) Based on Polymethacrylates and Pluronics, and Their Physicochemical Stability under Aqueous Conditions

This study describes the physicochemical characterisation of interpenetrating hydrogel networks (IHNs) composed of either poly(hydroxyethylmethacrylate, p(HEMA)) or poly(methacrylic acid, p(MAA)), and Pluronic block copolymers (grades F127, P123 and L121). IHNs were prepared by mixing the acrylate monomer with Pluronic block copolymers followed by free radical polymerisation. p(HEMA)-Pluronic blends were immiscible, evident from a lack of interaction between the two components (Raman spectroscopy) and the presence of the glass transitions (differential scanning calorimetry, DSC) of the two components. Conversely, IHNs of p(MAA) and each Pluronic were miscible, displaying a single glass transition and secondary bonding between the carbonyl group of p(MAA) and the ether groups in the Pluronic block copolymers (Raman and ATR-FTIR spectroscopy). The effect of storage of the IHNs in Tris buffer on the physical state of each Pluronic and on the loss of Pluronic from the IHNs were studied using DSC and gravimetric analysis, respectively. Pluronic loss from the IHNs was dependent on the grade of Pluronic, time of immersion in Tris buffer, and the nature of the IHN (p(HEMA) or p(MAA)). At equilibrium, the loss was greater from p(HEMA) than from p(MAA) IHNs, whereas increasing ratio of poly(propylene oxide) to poly(ethylene oxide) decreased Pluronic loss. The retention of each Pluronic grade was shown to be primarily due to its micellization; however, hydrogen bonding between Pluronic and p(MAA) (but not p(HEMA)) IHNs contributed to their retention.

Development and evaluation of an injectable ChitHCl-MgSO4-DDA hydrogel for bone regeneration: In vitro and in vivo studies on cell migration and osteogenesis enhancement

Nonunion and delayed union of the bone are situations in orthopedic surgery that can occur even if the bone alignment is correct and there is sufficient mechanical stability. Surgeons usually apply artificial bone grafts in bone fracture gaps or in bone defect sites for osteogenesis to improve bone healing; however, these bone graft materials have no osteoinductive or osteogenic properties, and fit the morphology of the fracture gap with difficulty. In this study, we developed an injectable chitosan-based hydrogel with MgSO4 and dextran oxidative, with the purpose to improve bone healing through introducing an engineered chitosan-based hydrogel. The developed hydrogel can gelate and fit with any morphology or shape, has good biocompatibility, can enhance the cell-migration capacity, and can improve extracellular calcium deposition. Moreover, the amount of new bone formed by injecting the hydrogel in the bone tunnel was assessed by an in vivo test. We believe this injectable chitosan-based hydrogel has great potential for application in the orthopedic field to improve fracture gap healing.

Multifunctional pH-responsive hydrogel dressings based on carboxymethyl chitosan: Synthesis, characterization fostering the wound healing

Antibiotic abuse is increasing the present rate of drug-resistant bacterial wound infections, producing a significant healthcare burden globally. Herein, we prepared a pH-responsive CMCS/PVP/TA (CPT) multifunctional hydrogel dressing by embedding the natural plant extract TA as a nonantibiotic and cross-linking agent in carboxymethyl chitosan (CMCS) and polyvinylpyrrolidone (PVP) to prompt wound healing. The CPT hydrogel demonstrated excellent self-healing, self-adaptive, and adhesion properties to match different wound requirements. Importantly, this hydrogel showed pH sensitivity and exhibited good activity against resistant bacteria and antioxidant activity by releasing TA in case of bacterial infection (alkaline). Furthermore, the CPT hydrogel exhibited coagulant ability and could rapidly stop bleeding within 30 s. The biocompatible hydrogel effectively accelerated wound healing in a full-thickness skin defect model by thickening granulation tissue, increasing collagen deposition, vascular proliferation, and M2-type macrophage polarization. In conclusion, this study demonstrates that multifunctional CPT hydrogel offers a candidate material with potential applications for infected skin wound healing.

Cutting-Edge Hydrogel Technologies in Tissue Engineering and Biosensing: An Updated Review

Hydrogels, known for their unique ability to retain large amounts of water, have emerged as pivotal materials in both tissue engineering and biosensing applications. This review provides an updated and comprehensive examination of cutting-edge hydrogel technologies and their multifaceted roles in these fields. Initially, the chemical composition and intrinsic properties of both natural and synthetic hydrogels are discussed, highlighting their biocompatibility and biodegradability. The manuscript then probes into innovative scaffold designs and fabrication techniques such as 3D printing, electrospinning, and self-assembly methods, emphasizing their applications in regenerating bone, cartilage, skin, and neural tissues. In the realm of biosensing, hydrogels' responsive nature is explored through their integration into optical, electrochemical, and piezoelectric sensors. These sensors are instrumental in medical diagnostics for glucose monitoring, pathogen detection, and biomarker identification, as well as in environmental and industrial applications like pollution and food quality monitoring. Furthermore, the review explores cross-disciplinary innovations, including the use of hydrogels in wearable devices, and hybrid systems, and their potential in personalized medicine. By addressing current challenges and future directions, this review aims to underscore the transformative impact of hydrogel technologies in advancing healthcare and industrial practices, thereby providing a vital resource for researchers and practitioners in the field.

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

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

Antimicrobial properties and biocompatibility of semi-synthetic carbohydrate-based ionic hydrogels

Hydrogels have gained significant interest in the last decades, especially in the medical sector, due to their versatile properties. While hydrogels from naturally occurring polysaccharides (e.g. cellulose) are well-known, those produced from polymerizable carbohydrate-based monomers remain underexplored. However, these semi-synthetic hydrogels offer the great advantage of having adjustable properties for customization depending on their application. The objective of this study was to characterize semi-synthetic carbohydrate-based ionic hydrogels produced from GVIM-I (glucosyl vinyl imidazolium iodide). The antimicrobial activity was evaluated using the disk diffusion method, which demonstrated that all samples exhibit inhibitory effects on the growth of Candida auris. In vitro biocompatibility was determined by cell viability studies with L929 mouse fibroblasts, and a correlation was observed between eluate concentration and cell viability. In particular, the type of initiator system employed for polymerization was found to affect cell viability. The direct contact assessments showed that specific pre-treatments of the hydrogels resulted in higher cell viability than non-treated hydrogels. The results also revealed the impact of crosslinker concentration and type and identified poly(ethylene glycol)diacrylate (PEGDA) 575 as a promising crosslinker for future medical applications. LC-MS analysis of the wash medium identified unreacted GVIM-I as the leached material, which is presumed to be the cause of the observed cytotoxicity. Overall, the study provides valuable insights into the characteristics of GVIM-I based hydrogels and sheds light on the factors that influence their cytotoxicity and potential for medical application.

Fabrication of In Situ-Cross-Linked N-Succinyl Chitosan/Oxidized Alginate Hydrogel-Loaded Ascorbic Acid and Biphasic Calcium Phosphate for Bone Tissue Engineering

Bone tissue engineering is a promising technology being studied globally to become an effective and sustainable method to treat the problems of damaged or diseased bones. In this work, we developed an in situ cross-linking hydrogel system that combined N-succinyl chitosan (NSC) and oxidized alginate (OA) at varying mixing ratios through Schiff base cross-linking. The hydrogel system also contains biphasic calcium phosphate (BCP) and ascorbic acid (AA), which could enhance biological characteristics and accelerate bone repair. The hydrogels' properties were examined through physicochemical tests such as scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction (XRD), pore size and porosity measurement, swelling ratio, degradation rate, AA release study, as well as cytocompatibility, including live/dead and cytotoxicity assays. The results revealed that the supplementation of AA and BCP components can affect the physico-mechanical properties of the hydrogel system. However, they exhibited noncytotoxic properties. Overall, the results demonstrated that the hydrogel composed of 3% (w/v) NSC and 3% (w/v) OA (NSC: OA volume ratio is 8:2) loaded with 40% (w/w) BCP and 0.3 mg/mL AA has the potential for bone regeneration.

A Multicomponent Microneedle Patch for the Delivery of Meloxicam for Veterinary Applications

This study evaluates the use of poly(vinyl alcohol), collagen, and chitosan blends for developing a microneedle patch for the delivery of meloxicam (MEL). Results confirm successful MEL encapsulation, structural integrity, and chemical stability even after ethylene oxide sterilization. Mechanical testing indicates the patch has the required properties for effective skin penetration and drug delivery, as demonstrated by load-displacement curves showing successful penetration of pig ear surfaces at 3N of normal load. In vitro imaging confirms the microneedle patch penetrates the pig's ear cadaver skin effectively and uniformly, with histological evaluation revealing the sustained presence and gradual degradation of microneedles within the skin. Additionally, in vitro drug diffusion experiments utilizing ballistic gel suggest that microneedles commence dissolution almost immediately upon insertion into the gel, steadily releasing the drug over 24 h. Furthermore, the microneedle patch demonstrates ideal drug release capabilities, achieving nearly 100% release of meloxicam content from a single patch within 18 h. Finally, in vivo studies using pigs demonstrate the successful dissolution and transdermal drug delivery efficacy of biodegradable microneedle patches delivering meloxicam in a porcine model, with over 70% of microneedles undergoing dissolution after 3 days. While low detectable meloxicam concentrations were observed in the bloodstream, high levels were detected in the ear tissue, confirming the release and diffusion of the drug from microneedles. This work highlights the potential of microneedle patches for controlled drug release in veterinary applications.

Injectable mineralized Sr-hydroxyapatite nanoparticles-loaded ɛ-polylysine-hyaluronic acid composite hydrogels for bone regeneration

In this study, multifunctional injectable mineralized antibacterial nanocomposite hydrogels were prepared by a homogenous distribution of high content of (up to 60 wt%) Sr-substituted hydroxyapatite (Sr-HAp) nanoparticles into covalently cross-linked ɛ-polylysine (ɛ-PL) and hyaluronic acid (HA) hydrogel network. The developed bone-targeted nanocomposite hydrogels were to synergistically combine the functional properties of bioactive Sr-HAp nanoparticles and antibacterial ɛ-PL-HA hydrogels for bone tissue regeneration. Viscoelasticity, injectability, structural parameters, degradation, antibacterial activity, and in vitro biocompatibility of the fabricated nanocomposite hydrogels were characterized. Physical performances of the ɛ-PL-HA hydrogels can be tailored by altering the mass ratio of Sr-HAp. The nanocomposite hydrogels revealed good stability against enzymatic degradation, which increased from 5 to 19 weeks with increasing the mass ratio of Sr-HAp from 40 % to 60 %. The loading of the Sr-HAp at relatively high mass ratios did not suppress the fast-acting and long-term antibacterial activity of the ɛ-PL-HA hydrogels against S. aureus and E. coli. The cell studies confirmed the cytocompatibility and pre-collagen I synthesis-promoting activity of the fabricated nanocomposite hydrogels.

Quantum Sensing Unravels Antioxidant Efficacy Within PCL/Matrigel Skin Equivalents

Skin equivalents (SE) that recapitulate biological and mechanical characteristics of the native tissue are promising platforms for assessing cosmetics and studying fundamental biological processes. Methods to achieve SEs with well-organized structure, and ideal biological and mechanical properties are limited. Here, the combination of melt electrowritten PCL scaffolds and cell-laden Matrigel to fabricate SE is described. The PCL scaffold provides ideal structural and mechanical properties, preventing deformation of the model. The model consists of a top layer for seeding keratinocytes to mimic the epidermis, and a bottom layer of Matrigel-based dermal compartment with fibroblasts. The compressive modulus and the biological properties after 3-day coculture indicate a close resemblance with the native skin. Using the SE, a testing system to study the damage caused by UVA irradiation and evaluate antioxidant efficacy is established. The effectiveness of Tea polyphenols (TPs) and L-ascorbic acid (Laa) is compared based on free radical generation. TPs are demonstrated to be more effective in downregulating free radical generation. Further, T1 relaxometry is used to detect the generation of free radicals at a single-cell level, which allows tracking of the same cell before and after UVA treatment.

The Development and Pre-Clinical Anti-Inflammatory Efficacy of a New Transdermal Ureasil-Polyether Hybrid Matrix Loaded with Flavonoid-Rich Annona muricata Leaf Extract

This study aimed to develop a novel ureasil-polyether transdermal hybrid matrix (U-PEO) loaded with Annona muricata concentrated extract (AMCE), which exhibits potent anti-inflammatory activity. The extract was obtained by maceration, a method that allowed for the extraction of a high concentration of flavonoids (39.27 mg/g of extract). In vivo tests demonstrated that 10 mg/kg of AMCE inhibited inflammation for 6 h. The physicochemical characterization of U-PEO with AMCE was conducted via a thermogravimetric analysis (TGA), while its surface was recorded using atomic force microscopy (AFM). The in vitro macroscopic swelling and release tests demonstrated the hydrophilic profile of the material and the percentage of AMCE released. The TGA results demonstrated that the system exhibited physical compatibility due to the thermal stability of U-PEO. Additionally, the AFM analysis revealed a rough and porous surface, with a particular emphasis on the system with AMCE. The release resulted in the liberation of 23.72% of AMCE within 24 h. Finally, the preclinical tests demonstrated that U-PEO with AMCE was also capable of effectively inhibiting inflammation for 6 h, a duration comparable to that of a commercial formulation. The results permit the advancement of the study towards the development of a transdermal system, thereby rendering its application in clinical studies feasible.

Supramolecular Hydrogels for 3D Biosensors and Bioassays

Supramolecular hydrogels play a pivotal role in many fields of biomedical research, including emerging applications in designing advanced tools for point-of-care testing, clinical diagnostics, and lab-on-chip analysis. This review outlines the growing relevance of supramolecular hydrogels in biosensing and bioassay devices, highlighting recent advancements that deliver increased sensitivity, real-time monitoring, and multiplexing capabilities through the distinctive properties of these nanomaterials. Furthermore, the exploration extends to additional applications, such as using hydrogels as three-dimensional matrices for cell-based assays.

Cell-adhesive double network self-healing hydrogel capable of cell and drug encapsulation: New platform to construct biomimetic environment with bottom-up approach

This study presents the development and characterization of a novel double-network self-healing hydrogel based on N-carboxyethyl chitosan (CEC) and oxidized dextran (OD) with the incorporation of crosslinked collagen (CEC-OD/COL-GP) to enhance its biological and physicochemical properties. The hydrogel formed via dynamic imine bond formation exhibited efficient self-healing within 30 min, and a compressive modulus recovery of 92 % within 2 h. In addition to its self-healing ability, CEC-OD/COL-GP possesses unique physicochemical characteristics including transparency, injectability, and adhesiveness to various substrates and tissues. Cell encapsulation studies confirmed the biocompatibility and suitability of the hydrogel as a cell-culture scaffold, with the presence of a collagen network that enhances cell adhesion, spreading, long-term cell viability, and proliferation. Leveraging their unique properties, we engineered assemblies of self-healing hydrogel modules for controlled spatiotemporal drug delivery and constructed co-culture models that simulate angiogenesis in tumor microenvironments. Overall, the CEC-OD/COL-GP hydrogel is a versatile and promising material for biomedical applications, offering a bottom-up approach for constructing complex structures with self-healing capabilities, controlled drug release, and support for diverse cell types in 3D environments. This hydrogel platform has considerable potential for advancements in tissue engineering and therapeutic interventions.

Hydrogels in Soft Robotics: Past, Present, and Future

The rise of soft robotics in recent years has motivated significant developments in smart materials (and vice versa), as these materials allow for more compact robotic designs thanks to the embodied intelligence that they provide. Hydrogels have long been postulated as one of the potential candidates to be used in soft robotics due to their softness, elasticity, and smart properties that can be tuned with nanomaterials. However, nowadays they represent only a small percentage of the materials used in the field. In this perspective, the drawbacks that have hindered their utilization so far are analyzed as well as the current state of hydrogel-based soft actuators, sensors, and manufacturing possibilities. The future improvements that need to be made to achieve a real application of hydrogels in soft robotics are also discussed.

Patterned PVA Hydrogels with 3D Petri Dish® Micro-Molds of Varying Topography for Spheroid Formation of HeLa Cancer Cells: In Vitro Assessment

Cell spheroids are an important three-dimensional (3D) model for in vitro testing and are gaining interest for their use in clinical applications. More natural 3D cell culture environments that support cell-cell interactions have been created for cancer drug discovery and therapy applications, such as the scaffold-free 3D Petri Dish® technology. This technology uses reusable and autoclavable silicone micro-molds with different topographies, and it conventionally uses gelled agarose for hydrogel formation to preserve the topography of the selected micro-mold. The present study investigated the feasibility of using a patterned Poly(vinyl alcohol) hydrogel using the circular topography 12-81 (9 × 9 wells) micro-mold to form HeLa cancer cell spheroids and compare them with the formed spheroids using agarose hydrogels. PVA hydrogels showed a slightly softer, springier, and stickier texture than agarose hydrogels. After preparation, Fourier transform infrared (FTIR) spectra showed chemical interactions through hydrogen bonding in the PVA and agarose hydrogels. Both types of hydrogels favor the formation of large HeLa spheroids with an average diameter of around 700-800 µm after 72 h. However, the PVA spheroids are more compact than those from agarose, suggesting a potential influence of micro-mold surface chemistry on cell behavior and spheroid formation. This was additionally confirmed by evaluating the spheroid size, morphology, integrity, as well as E-cadherin and Ki67 expression. The results suggest that PVA promotes stronger cell-to-cell interactions in the spheroids. Even the integrity of PVA spheroids was maintained after exposure to the drug cisplatin. In conclusion, the patterned PVA hydrogels were successfully prepared using the 3D Petri Dish® micro-molds, and they could be used as suitable platforms for studying cell-cell interactions in cancer drug therapy.

Effect of teak wood lignocellulose pretreatment on the performance of cellulose-graft-(net-poly(acrylamide-co-acrylic acid)) for water absorption and dye removal

Cellulose modified hydrogels can be produced directly from raw biopolymers in novel cellulose solvents such as NaOH/urea aqueous solution. The effect of cellulose characteristics on the synthesis of a cellulose-graft-(net-poly(acrylamide-co-acrylic acid)) and its performance as water absorbent/methylene blue dye removal material is analyzed. Three cellulose samples, one analytical grade and two obtained from teak wood sawdust with different pretreatments (one alkaline and the other, a novel one known as (gas phase) acid pretreatment) were compared. The starting raw celluloses were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and viscosity in cupri ethylenediamine hydroxide (CED) solution, whereas the chemically modified materials were characterized by SEM, FTIR, and TGA. The pretreatment used influences composition, crystallinity index and degree of polymerization (DP) of the cellulose obtained. The modified material produced with cellulose from alkaline pretreatment showed the highest swelling ratio in water absorption tests at room temperature (12,714 %); in contrast, the one with cellulose from acid pretreatment showed the lowest swelling ratio (7,470 %). However, this difference is not so significative in dye removal tests, where absorption capacity is 139 and 140 mg/g, respectively. The results indicate that cellulose composition, particularly structures with significant hemicellulose and lignin remaining content, has a major effect on the performance of modified materials for water absorption, and degree of polymerization has a major effect on adsorption capacity of methylene blue.

Photocrosslinked carboxymethylcellulose-based hydrogels: Synthesis, characterization for curcumin delivery and wound healing

Skin could protect our body and regenerate itself to against dysfunctional and disfiguring scars when faced with external injury. As wound dressings, hydrogels are biocompatible, hydrophilic and have a 3D structure similar to the extracellular matrix (ECM). In particular, hydrogels with drug-releasing capabilities are in acute wound healing. In this paper, photocrosslinked hydrogels served as wound dressing based on sodium carboxymethylcellulose (CMC) were prepared to promote wound healing. Photocrosslinked hydrogels were prepared by grafting lysine and allyl glycidyl ether (AGE) onto CMC and encapsulating curcumin (Cur). The synthesized hydrogels had the unique 3D porous structure with a swelling ratio up to 1300 % in aqueous solution. The drug release ratios of the hydrogels were 20.8 % in acid environment, and 14.4 % in alkaline environment. Notably, the hydrogels showed good biocompatibility and antibacterial properties and also exhibited the ability to accelerate the process of skin wound healing while prevent inflammation and scar formation when applied to a mouse skin wound model. As a result, the prepared hydrogels Gel-CLA@Cur showed great potential in wound healing.

Formation of Zwitterionic and Self-Healable Hydrogels via Amino-yne Click Chemistry for Development of Cellular Scaffold and Tumor Spheroid Phantom for MRI

In situ-forming biocompatible hydrogels have great potential in various medical applications. Here, we introduce a pH-responsive, self-healable, and biocompatible hydrogel for cell scaffolds and the development of a tumor spheroid phantom for magnetic resonance imaging. The hydrogel (pMAD) was synthesized via amino-yne click chemistry between poly(2-methacryloyloxyethyl phosphorylcholine-co-2-aminoethylmethacrylamide) and dialkyne polyethylene glycol. Rheology analysis, compressive mechanical testing, and gravimetric analysis were employed to investigate the gelation time, mechanical properties, equilibrium swelling, and degradability of pMAD hydrogels. The reversible enamine and imine bond mechanisms leading to the sol-to-gel transition in acidic conditions (pH ≤ 5) were observed. The pMAD hydrogel demonstrated potential as a cellular scaffold, exhibiting high viability and NIH-3T3 fibroblast cell encapsulation under mild conditions (37 °C, pH 7.4). Additionally, the pMAD hydrogel also demonstrated the capability for in vitro magnetic resonance imaging of glioblastoma tumor spheroids based on the chemical exchange saturation transfer effect. Given its advantages, the pMAD hydrogel emerges as a promising material for diverse biomedical applications, including cell carriers, bioimaging, and therapeutic agent delivery.

Incorporation of natural and synthetic polymers into honey hydrogel for wound healing: A review

Background and Aims

The difficulty in treating chronic wounds due to the prolonged inflammation stage has affected a staggering 6.5 million people, accompanied by 25 billion USD annually in the United States alone. A 1.9% rise in chronic wound prevalence among Medicare beneficiaries was reported from 2014 to 2019. Besides, the global wound care market values were anticipated to increase from USD 20.18 billion in 2022 to USD 30.52 billion in 2030, suggesting an expected rise in chronic wounds financial burdens. The lack of feasibility in using traditional dry wound dressings sparks hydrogel development as an alternative approach to tackling chronic wounds. Since ancient times, honey has been used to treat wounds, including burns, and ongoing studies have also demonstrated its wound-healing capabilities on cellular and animal models. However, the fluidity and low mechanical strength in honey hydrogel necessitate the incorporation of other polymers. Therefore, this review aims to unravel the characteristics and feasibility of natural (chitosan and gelatin) and synthetic (polyvinyl alcohol and polyethylene glycol) polymers to be incorporated in the honey hydrogel.

Methods

Relevant articles were identified from databases (PubMed, Google Scholar, and Science Direct) using keywords related to honey, hydrogel, and polymers. Relevant data from selected studies were synthesized narratively and reported following a structured narrative format.

Results

The importance of honey's roles and mechanisms of action in wound dressings were discussed. Notable studies concerning honey hydrogels with diverse polymers were also included in this article to provide a better perspective on fabricating customized hydrogel wound dressings for various types of wounds in the future.

Conclusion

Honey's incapability to stand alone in hydrogel requires the incorporation of natural and synthetic polymers into the hydrogel. With this review, it is hoped that the fabrication and commercialization of the desired honey composite hydrogel for wound treatment could be brought forth.

Injectable, Electroconductive, Free Radical Scavenging Silk Fibroin/Black Phosphorus/Glycyrrhizic Acid Nanocomposite Hydrogel for Enhancing Spinal Cord Repair

Spinal cord injury (SCI) often leads to a severe permanent disability. A poor inflammatory microenvironment and nerve electric signal conduction block are the main reasons for difficulty in spinal cord nerve regeneration. In this study, black phosphorus (BP) and glycyrrhizic acid (GA) are integrated into methacrylate-modified silk fibroin (SF) to construct a bifunctional injectable hydrogel (SF/BP/GA) with appropriate conductivity and the ability to inhibit inflammation to promote neuronal regeneration after SCI. This work discovers that the SF/BP/GA hydrogel can reduce the oxidative damage mediated by oxygen free radicals, promote the polarization of macrophages toward the anti-inflammatory M2 phenotype, reduce the expression of inflammatory factors, and improve the inflammatory microenvironment. Moreover, it induces neural stem cell (NSC) differentiation and neurosphere formation, restores signal conduction at the SCI site in vivo, and ameliorates motor function in mice with spinal cord hemisection, revealing a significant neural repair effect. An injectable, electroconductive, free-radical-scavenging hydrogel is a promising therapeutic strategy for SCI repair.

Release and Transport of Nanomaterials from Hydrogels Controlled by Temperature

Understanding the transport of nanoparticles from and within hydrogels is a key issue for the design of nanocomposite hydrogels for drug delivery systems and tissue engineering. To investigate the translocation of nanocarriers from and within hydrogel networks triggered by changes of temperature, ultrasmall (8 nm) and small (80 nm) silica nanocapsules are embedded in temperature-responsive hydrogels and non-responsive hydrogels. The ultrasmall silica nanocapsules are released from temperature-responsive hydrogels to water or transported to other hydrogels upon direct activation by heating or indirect activation by Joule heating; while, they are not released from non-responsive hydrogel. Programmable transport of nanocarriers from and in hydrogels provides insights for the development of complex biomedical devices and soft robotics.

Silk fibroin increases the elasticity of alginate-gelatin hydrogels and regulates cardiac cell contractile function in cardiac bioinks

Silk fibroin (SF) is a natural protein extracted fromBombyx morisilkworm thread. From its common use in the textile industry, it emerged as a biomaterial with promising biochemical and mechanical properties for applications in the field of tissue engineering and regenerative medicine. In this study, we evaluate for the first time the effects of SF on cardiac bioink formulations containing cardiac spheroids (CSs). First, we evaluate if the SF addition plays a role in the structural and elastic properties of hydrogels containing alginate (Alg) and gelatin (Gel). Then, we test the printability and durability of bioprinted SF-containing hydrogels. Finally, we evaluate whether the addition of SF controls cell viability and function of CSs in Alg-Gel hydrogels. Our findings show that the addition of 1% (w/v) SF to Alg-Gel hydrogels makes them more elastic without affecting cell viability. However, fractional shortening (FS%) of CSs in SF-Alg-Gel hydrogels increases without affecting their contraction frequency, suggesting an improvement in contractile function in the 3D cultures. Altogether, our findings support a promising pathway to bioengineer bioinks containing SF for cardiac applications, with the ability to control mechanical and cellular features in cardiac bioinks.

Eco-Friendly and Self-Sanitizing Microporous Cellulose Sponge (MCS)-Based Cooling Media for Mitigating Microbial Cross-Contamination in the Food Cold Chain

Maintaining precise temperature control is vital for cold chain food transport, as temperature fluctuations can cause significant food safety and quality issues. During transport, ice that melts can promote the growth of microbes and their spread, resulting in microbial cross-contamination. This study developed sustainable, non-melting, self-sanitizing "ice cubes" using food grade compositions including microporous cellulose sponges (MCS) and photosensitizers, aimed at enhancing temperature regulation and minimizing microbial contamination in the cold chain. Upon absorbing water, the MCS matched traditional ice in cooling efficiency and heat absorption and exhibit remarkable mechanical and thermal durability, withstanding multiple freeze-thaw cycles and compressive stresses. The cationic MCS combined with erythrosine B demonstrated strong self-sanitizing capabilities, effectively reducing microbial cross-contamination in food models. Additionally, the release rates of photosensitizers from the MCS can be modulated by altering environmental ionic strength. This research offers viable solutions to address microbial cross-contamination challenges in current cold chain systems.

Enhanced Vascular-like Network Formation of Encapsulated HUVECs and ADSCs Coculture in Growth Factors Conjugated GelMA Hydrogels

Tissue engineering primarily aimed to alleviate the insufficiency of organ donations worldwide. Nonetheless, the survival of the engineered tissue is often compromised due to the complexity of the natural organ architectures, especially the vascular system inside the organ, which allows food-waste transfer. Thus, vascularization within the engineered tissue is of paramount importance. A critical aspect of this endeavor is the ability to replicate the intricacies of the extracellular matrix and promote the formation of functional vascular networks within engineered constructs. In this study, human adipose-derived stem cells (hADSCs) and human umbilical vein endothelial cells (HUVECs) were cocultured in different types of gelatin methacrylate (GelMA). In brief, pro-angiogenic signaling growth factors (GFs), vascular endothelial growth factor (VEGF165) and basic fibroblast growth factor (bFGF), were conjugated onto GelMA via an EDC/NHS coupling reaction. The GelMA hydrogels conjugated with VEGF165 (GelMA@VEGF165) and bFGF (GelMA@bFGF) showed marginal changes in the chemical and physical characteristics of the GelMA hydrogels. Moreover, the conjugation of these growth factors demonstrated improved cell viability and cell proliferation within the hydrogel construct. Additionally, vascular-like network formation was observed predominantly on GelMA@GrowthFactor (GelMA@GF) hydrogels, particularly on GelMA@bFGF. This study suggests that growth factor-conjugated GelMA hydrogels would be a promising biomaterial for 3D vascular tissue engineering.

Bioprinting Soft 3D Models of Hematopoiesis using Natural Silk Fibroin-Based Bioink Efficiently Supports Platelet Differentiation

Hematopoietic stem and progenitor cells (HSPCs) continuously generate platelets throughout one's life. Inherited Platelet Disorders affect ≈ 3 million individuals worldwide and are characterized by defects in platelet formation or function. A critical challenge in the identification of these diseases lies in the absence of models that facilitate the study of hematopoiesis ex vivo. Here, a silk fibroin-based bioink is developed and designed for 3D bioprinting. This bioink replicates a soft and biomimetic environment, enabling the controlled differentiation of HSPCs into platelets. The formulation consisting of silk fibroin, gelatin, and alginate is fine-tuned to obtain a viscoelastic, shear-thinning, thixotropic bioink with the remarkable ability to rapidly recover after bioprinting and provide structural integrity and mechanical stability over long-term culture. Optical transparency allowed for high-resolution imaging of platelet generation, while the incorporation of enzymatic sensors allowed quantitative analysis of glycolytic metabolism during differentiation that is represented through measurable color changes. Bioprinting patient samples revealed a decrease in metabolic activity and platelet production in Inherited Platelet Disorders. These discoveries are instrumental in establishing reference ranges for classification and automating the assessment of treatment responses. This model has far-reaching implications for application in the research of blood-related diseases, prioritizing drug development strategies, and tailoring personalized therapies.

Programming viscoelastic properties in a complexation gel composite by utilizing entropy-driven topologically frustrated dynamical state

Hydrogel composites in an aqueous media with viscoelastic properties and elastic modulus that can be precisely tailored are desirable to mimic many biological tissues ranging from mucus, vitreous humor, and nucleus pulposus as well as build up biosensors. Without altering the chemistry, tuning the physical interactions and structures to govern the viscoelastic properties of the hydrogels is indispensable for their applications but quite limited. Here we design a complexation gel composite and utilize the physical principle of topologically frustrated dynamical state to tune the correlated structures between the guest polycation chains and negatively charged host gels. We precisely quantify the mesh size of the host gel and guest chain size. By designing various topologically correlated structures, a viscoelastic moduli map can be built up, ranging from tough to ultrasoft, and from elastic-like with low damping properties to viscous-like with high damping properties. We also tune the swelling ratio by using entropy effect and discover an Entropy-driven Topologically Isovolumetric Point. Our findings provide essential physics to understand the relationship between entropy-driven correlated structures and their viscoelastic properties of the complexation hydrogel composites and will have diverse applications in tissue engineering and soft biomaterials.

Bactericidal Chitosan Derivatives and Their Superabsorbent Blends with ĸ-Carrageenan

The aim of this work is research dedicated to the search for new bactericidal systems for use in cosmetic formulations, dermocosmetics, or the production of wound dressings. Over the last two decades, chitosan, due to its special biological activity, has become a highly indispensable biopolymer with very wide application possibilities. Reports in the literature on the antibacterial effects of chitosan are very diverse, but our research has shown that they can be successfully improved through chemical modification. Therefore, in this study, results on the synthesis of new chitosan-based Schiff bases, dCsSB-SFD and dCsSB-PCA, are obtained using two aldehydes: sodium 4-formylbenzene-1,3-disulfonate (SFD) and 2-pyridine carboxaldehyde (PCA), respectively. Chitosan derivatives synthesized in this way demonstrate stronger antimicrobial activity. Carrying out the procedure of grafting chitosan with a caproyl chain allowed obtaining compatible blends of chitosan derivatives with κ-carrageenan, which are stable hydrogels with a high swelling coefficient. Furthermore, the covalently bounded poly(ε-caprolactone) (PCL) chain improved the solubility of obtained polymers in organic solvents. In this respect, the Schiff base-containing polymers obtained in this study, with special hydrogel and antimicrobial properties, are very promising materials for potential use as a controlled-release formulation of both hydrophilic and hydrophobic drugs in cosmetic products for skin health.

Advances in Hydrogel-Based Drug Delivery Systems

Hydrogels, with their distinctive three-dimensional networks of hydrophilic polymers, drive innovations across various biomedical applications. The ability of hydrogels to absorb and retain significant volumes of water, coupled with their structural integrity and responsiveness to environmental stimuli, renders them ideal for drug delivery, tissue engineering, and wound healing. This review delves into the classification of hydrogels based on cross-linking methods, providing insights into their synthesis, properties, and applications. We further discuss the recent advancements in hydrogel-based drug delivery systems, including oral, injectable, topical, and ocular approaches, highlighting their significance in enhancing therapeutic outcomes. Additionally, we address the challenges faced in the clinical translation of hydrogels and propose future directions for leveraging their potential in personalized medicine and regenerative healthcare solutions.

A Comprehensive Review of Hydrogel-Based Drug Delivery Systems: Classification, Properties, Recent Trends, and Applications

As adaptable biomaterials, hydrogels have shown great promise in several industries, which include the delivery of drugs, engineering of tissues, biosensing, and regenerative medicine. These hydrophilic polymer three-dimensional networks have special qualities like increased content of water, soft, flexible nature, as well as biocompatibility, which makes it excellent candidates for simulating the extracellular matrix and promoting cell development and tissue regeneration. With an emphasis on their design concepts, synthesis processes, and characterization procedures, this review paper offers a thorough overview of hydrogels. It covers the various hydrogel material types, such as natural polymers, synthetic polymers, and hybrid hydrogels, as well as their unique characteristics and uses. The improvements in hydrogel-based platforms for controlled drug delivery are examined. It also looks at recent advances in bioprinting methods that use hydrogels to create intricate tissue constructions with exquisite spatial control. The performance of hydrogels is explored through several variables, including mechanical properties, degradation behaviour, and biological interactions, with a focus on the significance of customizing hydrogel qualities for particular applications. This review paper also offers insights into future directions in hydrogel research, including those that promise to advance the discipline, such as stimuli-responsive hydrogels, self-healing hydrogels, and bioactive hydrogels. Generally, the objective of this review paper is to provide readers with a detailed grasp of hydrogels and all of their potential uses, making it an invaluable tool for scientists and researchers studying biomaterials and tissue engineering.

Rapid self-healing carboxymethyl chitosan/hyaluronic acid hydrogels with injectable ability for drug delivery

In this study, the quaternized carboxymethyl chitosan (QCMCS), oxidized hyaluronic acid (OHA), 3,3'-dithiobis-(propionohydrazide) (DTP) were used as raw materials for the synthesis of hydrogels with excellent properties as carriers for drug release. The hydrogels were prepared by a simple "one-pot" method without external stimuli on the basis of interactions between formed dynamic covalent bonds (imine bonds, acylhydrazone bonds, disulfide bonds) and hydrogen bonds. The hydrogels had rapid self-healing properties, with a self-healing rate of 96 % after 30 min, as well as good pH responsiveness and excellent cytocompatibility (up to 98 % cell survival). The compressive stress of the hydrogels reached 423 kPa. Moreover, a representative drug (acetylsalicylic acid) demonstrated sustained release in the hydrogels (>72 h). The drug release behaviour was shown to be consistent with the Fick diffusion mechanism by kinetic modelling. Collectively, the findings demonstrate that the QCMCS + OHA + DTP injectable self-healing hydrogels are a potential material for the construction of pH-controlled drug delivery platforms.

Chitosan/dialdehyde cellulose hydrogels with covalently anchored polypyrrole: Novel conductive, antibacterial, antioxidant, immunomodulatory, and anti-inflammatory materials

In this work, conductive composite hydrogels with covalently attached polypyrrole (PPy) nanoparticles are prepared. Hydrogels are based on partially re-acetylated chitosan soluble at physiological pH without any artificial structural modifications or need for an acidic environment, which simplifies synthesis and purification. Low-toxic and sustainable dialdehyde cellulose (DAC) was used for crosslinking chitosan and covalent anchoring of PPy colloidal particles. The condensation reaction between DAC and PPy is reported for the first time and improves not only the anchoring of PPy particles but also control over the properties of the final composite. The soluble chitosan and PPy particles are shown to act in synergy, which improves the biological properties of the materials. Prepared composite hydrogels are non-cytotoxic, non-irritating, antibacterial, can capture reactive oxygen species often related to excessive inflammation, have conductivity similar to human tissues, enhance in vitro cell growth (migration assay), and have immunomodulatory effects related to the stimulation of neutrophils and macrophages. The covalent attachment of PPy also strengthens the hydrogel network. The aldol condensation as a method for PPy covalent anchoring thus presents an interesting possibility for the development of advanced biomaterials in the future.

Multifunctional biomimetic hydrogel dressing provides anti-infection treatment and improves immunotherapy by reprogramming the infection-related wound microenvironment

The advancement of biomaterials with antimicrobial and wound healing properties continues to present challenges. Macrophages are recognized for their significant role in the repair of infection-related wounds. However, the interaction between biomaterials and macrophages remains complex and requires further investigation. In this research, we propose a new sequential immunomodulation method to enhance and expedite wound healing by leveraging the immune properties of bacteria-related wounds, utilizing a novel mixed hydrogel dressing. The hydrogel matrix is derived from porcine acellular dermal matrix (PADM) and is loaded with a new type of bioactive glass nanoparticles (MBG) doped with magnesium (Mg-MBG) and loaded with Curcumin (Cur). This hybrid hydrogel demonstrates controlled release of Cur, effectively eradicating bacterial infection in the early stage of wound infection, and the subsequent release of Mg ions (Mg2+) synergistically inhibits the activation of inflammation-related pathways (such as MAPK pathway, NF-κB pathway, TNF-α pathway, etc.), suppressing the inflammatory response caused by infection. Therefore, this innovative hydrogel can safely and effectively expedite wound healing during infection. Our design strategy explores novel immunomodulatory biomaterials, offering a fresh approach to tackle current clinical challenges associated with wound infection treatment.

Hydrogel design to overcome thermal resistance and ROS detoxification in photothermal and photodynamic therapy of cancer

Responsive heat resistance (by heat shock protein upregulation) and spontaneous reactive oxygen species (ROS) detoxification have been regarded as the major obstacles for photothermal/photodynamic therapy of cancer. To overcome the thermal resistance and improve ROS susceptibility in breast cancer therapy, Au ion-crosslinked hydrogels including indocyanine green (ICG) and polyphenol are devised. Au ion has been introduced for gel crosslinking (by catechol-Au3+ coordination), cellular glutathione depletion, and O2 production from cellular H2O2. ICG can generate singlet oxygen from O2 (for photodynamic therapy) and induce hyperthermia (for photothermal therapy) under the near-infrared laser exposure. (-)-Epigallocatechin gallate downregulates heat shock protein to overcome heat resistance during hyperthermia and exerts multiple anticancer functions in spite of its ironical antioxidant features. Those molecules are concinnously engaged in the hydrogel structure to offer fast gel transformation, syringe injection, self-restoration, and rheological tuning for augmented photo/chemotherapy of cancer. Intratumoral injection of multifunctional hydrogel efficiently suppressed the growth of primary breast cancer and completely eliminated the residual tumor mass. Proposed hydrogel system can be applied to tumor size reduction prior to surgery of breast cancer and the complete remission after its surgery.

Ultrafast self-gelling, sprayable, and adhesive carboxymethyl chitosan/poly-γ-glutamic acid/oxidized dextran powder for effective gastric perforation hemostasis and wound healing

The rapid and effective hemostasis of gastrointestinal bleeding sites remains an urgent clinical challenge. In this study, an ultrafast self-gelling, sprayable, and adhesive carboxymethyl chitosan/poly-γ-glutamic acid/oxidized dextran (CPO) powder was designed for gastric perforation hemostasis and healing. When the CPO powder was sprayed to the gastric perforation site, the CPO powder absorbed water from the blood and concentrate blood cells and clotting factors to achieve the purpose of rapid hemostasis. During the hemostasis, the CPO powder formed a hydrogel in situ through the formation of amide bonds and Schiff base bonds within 15 s, forming a physical barrier to cover the wound surface. Concurrently, the aldehyde group (-CHO) of oxidized dextran formed additional Schiff base bonds with the amino group (-NH2) of the tissue, enabling the CPO powder with wound surface adhesion. Moreover, the CPO powder was shown to have excellent in vitro and in vivo antibacterial properties and it was able to promote the healing of infected wounds in a mouse model. In summary, CPO powder provides a promising idea for the rational design of gastrointestinal hemostatic agents.

Facilely Prepared Thirsty Granules Arouse Tough Wet Adhesion on Overmoist Wounds for Hemostasis and Tissue Repair

Bioadhesives have been widely used in hemostasis and tissue repair, but the overmoist and wet nature of wound surface (due to the presence of blood and/or wound exudate) has led to poor wet adhesion of bioadhesives, which interrupts the continuous care of wounds. Here, a thirsty polyphenolic silk granule (Tan@SF-pwd-hydro), which absorbs blood and exudate to self-convert to robust bioadhesives (Tan@SF-gel-hydro) in situ, was facilely developed in this study for enhanced wet adhesion toward hemostasis and tissue repair. Tan@SF-pwd-hydro could shield wounds' wetness and immediately convert itself to Tan@SF-gel-hydro to seal wounds for hemorrhage control and wound healing. The maximum adhesiveness of Tan@SF-gel-hydro over wet pigskin was as high as 59.8 ± 2.1 kPa. Tan@SF-pwd-hydro is a promising transformative dressing for hemostasis and tissue repair since its hemostatic time was approximately half of that of the commercial hemostatic product, CeloxTM, and its healing period was much shorter than that of the commercial bioadhesive product, TegadermTM. This pioneering study utilized adverse wetness over wounds to arouse robust adhesiveness by converting thirsty granules to bioadhesives in situ, creatively turning adversity into opportunities. The facile fabrication approach also offers new perspectives for manufacturing sustainability of biomaterials.