Electro-stimulated drug release by methacrylated hyaluronic acid-based conductive hydrogel with enhanced mechanical properties

Synthesis, characterization of thiolated hyaluronic acid and evaluation of its encapsulation effects on Limosilactobacillus reuteri HR7

Hyaluronic acid (HA) was thiol-modified by adding different concentrations of L-Cysteine (1 mmol, 2 mmol, 3 mmol, 4 mmol, 5 mmol and 6 mmol) and the resulting polymers (HA-SH) were characterized. The results of FTIR, 1H NMR, XRD, SEM and DSC all confirmed the success of thiol modification, accompanied by free thiol group content of 3169.51-3913.44 μmol/g. Sulfur element was only detected in HA-SH, accounting for 1.12 %-1.23 %. The Mw and particle size were decreased after thiol modification, representing a more uniform polysaccharide conformation, which was beneficial for the encapsulation of probiotics. Rheological analysis showed that the hydrogel prepared by HA displayed viscoelastic fluid properties, while the hydrogels prepared by HA-SH exhibited solid-like gel properties, indicating enhanced gelation properties after thiol modification. Subsequently, the hydrogels were applied to probiotics encapsulation to explore the effects on gastrointestinal tolerance. A higher encapsulation efficiency was observed in HA-SH hydrogel with enhanced gastrointestinal tolerance, increasing by 38.15 % on average. These results demonstrated that thiolation was a good strategy for polysaccharide modification and hydrogel formed by HA-SH was a more promising encapsulation and delivery system for probiotics compared with HA.

Acrylamide/Alyssum campestre seed gum hydrogels enhanced with titanium carbide: Rheological insights for cardiac tissue engineering

This study investigates the use of acrylamide and Alyssum campestre seed gum (ACSG) to create hydrogel composites with enhanced electrical and mechanical properties by incorporating titanium carbide (TiC). The composites were analyzed through techniques such as FTIR, SEM, TEM, TGA, swelling, rheology, tensile, electrical conductivity, antibacterial, and MTT assays. XRD analysis showed that 0.5 % TiC NPs were exfoliated in the hydrogel, while 1 % was intercalated. SEM images showed that ACSG created a semi-interpenetrating polymer network with interconnected cavities averaging 9.1 μm, which reduced to 3.6 μm with 0.5%TiC and 51.8 nm with 1%TiC due to increased crosslinking density. TGA results confirmed hydrogel stability at autoclave temperatures. Rheological testing revealed that the hydrogel exhibited a maximum resistance of 317 kPa. The addition of 1 % TiC enhanced its electrical conductivity to 1.5 × 10-2S/cm, making it suitable for applications in cardiac tissue engineering. MTT assays confirmed the hydrogel's biocompatibility and demonstrated its superior antibacterial activity against Staphylococcus aureus compared to Escherichia coli. The AM/ACSG/TiC hydrogel is a promising material for cardiac tissue engineering because of its adjustable mechanical properties, excellent electrical conductivity, and strong compatibility with cell cultures. The addition of ACSG improves the hydrogel's rheological behavior, which is crucial for promoting effective cell growth.

In situ photocrosslinkable hydrogel treats radiation-induced skin injury by ROS elimination and inflammation regulation

The clinical management of radiation-induced skin injury (RSI) poses a significant challenge, primarily due to the acute damage caused by an overabundance of reactive oxygen species (ROS) and the ongoing inflammatory microenvironment. Here, we designed a dual-network hydrogel composed of 5 % (w/v) Pluronic F127 diacrylate and 2 % (w/v) hyaluronic acid methacryloyl, termed the FH hydrogel. To confer antioxidant and anti-inflammation properties to the hydrogel, we incorporated PVP-modified Prussian blue nanoparticles (PPBs) and resveratrol (Res) to form PHF@Res hydrogels. PHF@Res hydrogels not only exhibited multiple free radical scavenging activities (DPPH, ABTS), but also displayed multiple enzyme-like activities (POD-, catalase). Meanwhile, PHF@Res-2 hydrogels significantly suppressed intracellular ROS and promoted the migration of fibroblasts in a high-oxidative stress environment. Moreover, in the RSI mouse model, the PHF@Res-2 hydrogel regulated inflammatory factors and collagen deposition, significantly reduced epithelial hyperplasia, promoted limb regeneration and neovascularization, and accelerated wound healing, outperforming the commercial antiradiation formulation, Kangfuxin. The PHF@Res-2 hydrogel dressing shows great potential in accelerating wound healing in RSI, offering tremendous promise for clinical wound management and regeneration.

Electrically conductive "SMART" hydrogels for on-demand drug delivery

In the current transformative era of biomedicine, hydrogels have established their presence in biomaterials due to their superior biocompatibility, tuneability and resemblance with native tissue. However, hydrogels typically exhibit poor conductivity due to their hydrophilic polymer structure. Electrical conductivity provides an important enhancement to the properties of hydrogel-based systems in various biomedical applications such as drug delivery and tissue engineering. Consequently, researchers are developing combinatorial strategies to develop electrically responsive "SMART" systems to improve the therapeutic efficacy of biomolecules. Electrically conductive hydrogels have been explored for various drug delivery applications, enabling higher loading of therapeutic cargo with on-demand delivery. This review emphasizes the properties, mechanisms, fabrication techniques and recent advancements of electrically responsive "SMART" systems aiding on-site drug delivery applications. Additionally, it covers prospects for the successful translation of these systems into clinical research.

Photothermal-enhanced silver nanocluster bioactive glass hydrogels for synergistic antimicrobial and promote wound healing

Antibacterial hydrogels are promising for combating infections and promoting wound healing. Nevertheless, excessive antibiotics induce resistance, and high metal ion levels cause cytotoxicity, complicating healing. Here, we introduce a hydrogel incorporating polydopamine-coated bioactive glass (BGs@PDA) on reduced graphene oxide (rGO) with photothermal therapy (PTT) and silver nanoclusters (AgNCs) for synergistic antibacterial treatment. This design enables rapid bacterial eradication and controlled release. Near-infrared-assisted heating provides noninvasive, targeted hyperthermia, killing bacteria quickly. Post-PTT addition of low-dose AgNCs reduces toxicity while enhancing antimicrobial efficacy and biocompatibility. BGs@PDA-loaded rGO prevents sedimentation, improves photothermal conversion and conductivity, and stabilizes the hydrogel structure. Constructed from chitosan and hydroxyethyl cellulose, the hydrogel is cross-linked by PDA and rGO, enhancing mechanical strength, adhesion, self-healing, free radical scavenging, and continuous wound exudate absorption. PDA encapsulation facilitates BGs degradation, improving the wound microenvironment. In vivo studies confirm accelerated healing and potent synergistic antibacterial effects, indicating its potential as a low-dose, antibiotic-free alternative for clinical wound infection management.

Iontophoresis-Integrated Smart Microneedle Delivery Platform for Efficient Transdermal Delivery and On-Demand Insulin Release

Transdermal insulin delivery in a painless, convenient, and on-demand way remains a long-standing challenge. A variety of smart microneedles (MNs) fabricated by glucose-responsive phenylboronic acid hydrogels have been previously developed to provide painless and autonomous insulin release in response to a glucose level change. However, like the majority of MNs, their transdermal delivery efficiency was still relatively low compared to that with subcutaneous injection. Herein, we report an iontophoresis (ITP)-integrated smart MNs delivery platform with enhanced transdermal delivery efficiency and delivery depth. Carbon nanotubes (CNTs) were induced in the boronate-containing hydrogel to develop a semi-interpenetrating network hydrogel with enhanced stiffness and conductivity. Remarkably, ITP not only facilitated efficient and deeper transdermal delivery of insulin via electroosmosis and electrophoresis but also well-maintained glucose responsiveness. This ITP-combined smart MNs delivery platform, which could provide on-demand insulin delivery in a painless, convenient, and safe way, is promising to achieve persistent glycemic control. Furthermore, transdermal delivery of payloads with a wide size range was achieved by this delivery platform and thus shed light on the development of an efficient transdermal delivery platform with deep skin penetration in a minimally invasive way.

Wearable dual-drug controlled release patch for psoriasis treatment

Wearable drug delivery systems (DDS) have made significant advancements in the field of precision medicine, offering precise regulation of drug dosage, location, and timing. The performance qualities that wearable DDS has always strived for are simplicity, efficiency, and intelligence. This paper proposes a wearable dual-drug synergistic release patch. The patch is powered by a built-in magnesium battery and utilizes a hydrogel containing viologen-based hyperbranched polyamidoamine as both a cathode material and an integrated drug reservoir. This design allows for the simultaneous release of both dexamethasone and tannic acid, overcoming the limitations of monotherapy and ensuring effective synergy for on-demand therapy. In a mouse model with praziquimod-induced psoriasis, the patch demonstrated therapeutic efficacy at a low voltage. The inflammatory skin returned to normal after 5 days with the on-demand release of dual drugs. This work provides a promising treatment option considering its straightforward construction and the therapeutic advantages of dual-drug synergy.

Single/Multi-Network Conductive Hydrogels-A Review

Hydrogels made from conductive organic materials have gained significant interest in recent years due to their wide range of uses, such as electrical conductors, freezing resistors, biosensors, actuators, biomedical engineering materials, drug carrier, artificial organs, flexible electronics, battery solar cells, soft robotics, and self-healers. Nevertheless, the insufficient level of effectiveness in electroconductive hydrogels serves as a driving force for researchers to intensify their endeavors in this domain. This article provides a concise overview of the recent advancements in creating self-healing single- or multi-network (double or triple) conductive hydrogels (CHs) using a range of natural and synthetic polymers and monomers. We deliberated on the efficacy, benefits, and drawbacks of several conductive hydrogels. This paper emphasizes the use of natural polymers and innovative 3D printing CHs-based technology to create self-healing conductive gels for flexible electronics. In conclusion, advantages and disadvantages have been noted, and some potential opportunities for self-healing single- or multi-network hydrogels have been proposed.

On the design of lignin reinforced acrylic acid/hyaluronic acid adhesive hydrogels with conductive PEDOT:HA nanoparticles

Hydrogels are of great importance in biomedical engineering. They possess the ability to mimic bodily soft tissues, and this allows exciting possibilities for applications such as tissue engineering, drug delivery and wound healing, however much work remains on stability and mechanical robustness to allow for translation to clinical applications. The work herein describes the synthesis and analysis of a biocompatible, versatile hydrogel that has tailorable swelling, high stability when swollen and thermal stability. The synthesis methods used produce a hydrogel with high elasticity, good mechanical properties and rapid crosslinking whilst displaying biocompatibility, adhesion, and conductivity. It has been shown that cell viability in the samples is above 80 % in all cases, a Young's Modulus of up to 85 kPa and high swelling degrees were achieved. These materials show potential for use in numerous applications such as adhesive sensors, skin grafts and drug delivery systems.

Improved and Highly Reproducible Synthesis of Methacrylated Hyaluronic Acid with Tailored Degrees of Substitution

Methacrylated hyaluronic acid (HAMA) is a versatile material that has gained significant attention in various pharmaceutical and biomedical applications. This biocompatible material can be photo-cross-linked in the presence of Irgacure 2959 (I2959) to produce hydrogels. Controlling the degree of methacrylation (DM) is crucial since it plays a pivotal role in determining the properties and thus the potential applications of the gels. We report herein a new green approach for the highly controlled and tailored modification of hyaluronic acid (HA) with methacrylic anhydride (MA). The reaction conditions of previously reported procedures were optimized, leading to a decreased reaction time (3 h instead of 24 h) and consumption of fewer equivalents of MA (5 equiv instead of 20) and water as the sole solvent. By changing the amount of base added, HAMA with three different DMs was obtained: 19, 35, and 60%. The influence of the molecular weight of HA, degree of substitution, and concentration of the HAMA solution prior to photo-cross-linking on the rheological, swelling, and degradation properties of HAMA hydrogels was also studied in this work.

Exosomes encapsulated in hydrogels for effective central nervous system drug delivery

The targeted delivery of pharmacologically active molecules, metabolites, and growth factors to the brain parenchyma has become one of the major challenges following the onset of neurodegeneration and pathological conditions. The therapeutic effect of active biomolecules is significantly impaired after systemic administration in the central nervous system (CNS) because of the blood-brain barrier (BBB). Therefore, the development of novel therapeutic approaches capable of overcoming these limitations is under discussion. Exosomes (Exo) are nano-sized vesicles of endosomal origin that have a high distribution rate in biofluids. Recent advances have introduced Exo as naturally suitable bio-shuttles for the delivery of neurotrophic factors to the brain parenchyma. In recent years, many researchers have attempted to regulate the delivery of Exo to target sites while reducing their removal from circulation. The encapsulation of Exo in natural and synthetic hydrogels offers a valuable strategy to address the limitations of Exo, maintaining their integrity and controlling their release at a desired site. Herein, we highlight the current and novel approaches related to the application of hydrogels for the encapsulation of Exo in the field of CNS tissue engineering.

A comprehensive review on the inherent and enhanced antifouling mechanisms of hydrogels and their applications

Biofouling remains a persistent challenge within the domains of biomedicine, tissue engineering, marine industry, and membrane separation processes. Multifunctional hydrogels have garnered substantial attention due to their complex three-dimensional architecture, hydrophilicity, biocompatibility, and flexibility. These hydrogels have shown notable advances across various engineering disciplines. The antifouling efficacy of hydrogels typically covers a range of strategies to mitigate or inhibit the adhesion of particulate matter, biological entities, or extraneous pollutants onto their external or internal surfaces. This review provides a comprehensive review of the antifouling properties and applications of hydrogels. We first focus on elucidating the fundamental principles for the inherent resistance of hydrogels to fouling. This is followed by a comprehensive investigation of the methods employed to enhance the antifouling properties enabled by the hydrogels' composition, network structure, conductivity, photothermal properties, release of reactive oxygen species (ROS), and incorporation of silicon and fluorine compounds. Additionally, we explore the emerging prospects of antifouling hydrogels to alleviate the severe challenges posed by surface contamination, membrane separation and wound dressings. The inclusion of detailed mechanistic insights and the judicious selection of antifouling hydrogels are geared toward identifying extant gaps that must be bridged to meet practical requisites while concurrently addressing long-term antifouling applications.

Preparation and application of curcumin loaded with citric acid crosslinked chitosan-gelatin hydrogels

While oral administration offers safety benefits, its therapeutic efficacy is hindered by various physiological factors within the body. In this study, a novel approach was explored using a matrix consisting of 2 % chitosan and 2 % gelatin, with citric acid (CA) serving as a green cross-linking agent (ranging from 0.4 % to 1.0 %), and curcumin (Cur) as the model drug to formulate hydrogel carriers. The results showed that a 0.4 % CA concentration, the hydrogel (CGA0.4) reached swelling equilibrium in deionized water within 40 min, exhibiting a maximum swelling index was 539 g/g. The addition of Cur to the CGA hydrogel (CGACur) notably enhanced release efficiency, particularly in simulated intestinal fluid, where Cur release rates exceeded 40 % within 100 min compared to below 8 % in other solutions. Among these hydrogels, CGA0.4Cur exhibited the fastest degradation rate in the combined solution, reaching >90 % degradation after 7 days. Additionally, Cur and CA demonstrated positive effects on the tensile strength, antioxidant activity and antibacterial activity of hydrogels. Compare to the bioaccessibility of CGC (27 %), those of CGACur had increased to over 34 %. These findings offer provide theoretical support for CA-crosslinked chitosan/gelatin gels in delivering hydrophobic bioactive molecules and their application in intestinal drug delivery system.

Layer-by-layer designer nanoarchitectonics for physical and chemical communications in functional materials

Nanoarchitectonics, as a post-nanotechnology concept, constructs functional materials and structures using nanounits of atoms, molecules, and nanomaterials as materials. With the concept of nanoarchitectonics, asymmetric structures, and hierarchical organization, rather than mere assembly and organization of structures, can be produced, where rational physical and chemical communications will lead to the development of more advanced functional materials. Layer-by-layer assembly can be a powerful tool for this purpose, as exemplified in this feature paper. This feature article explores the possibility of constructing advanced functional systems based on recent examples of layer-by-layer assembly. We will illustrate both the development of more basic methods and more advanced nanoarchitectonics systems aiming towards practical applications. Specifically, the following sections will provide examples of (i) advancement in basics and methods, (ii) physico-chemical aspects and applications, (iii) bio-chemical aspects and applications, and (iv) bio-medical applications. It can be concluded that materials nanoarchitectonics based on layer-by-layer assembly is a useful method for assembling asymmetric structures and hierarchical organization, and is a powerful technique for developing functions through physical and chemical communication.

State of the Art and Current Challenges on Electroactive Biomaterials and Strategies for Neural Tissue Regeneration

The loss or failure of an organ/tissue stands as one of the healthcare system's most prevalent, devastating, and costly challenges. Strategies for neural tissue repair and regeneration have received significant attention due to their particularly strong impact on patients' well-being. Many research efforts are dedicated not only to control the disease symptoms but also to find solutions to repair the damaged tissues. Neural tissue engineering (TE) plays a key role in addressing this problem and significant efforts are being carried out to develop strategies for neural repair treatment. In the last years, active materials allowing to tune cell-materials interaction are being increasingly used, representing a recent paradigm in TE applications. Among the most important stimuli influencing cell behavior are the electrical and mechanical ones. In this way, materials with the ability to provide this kind of stimuli to the neural cells seem to be appropriate to support neural TE. In this scope, this review summarizes the different biomaterials types used for neural TE, highlighting the relevance of using active biomaterials and electrical stimulation. Furthermore, this review provides not only a compilation of the most relevant studies and results but also strategies for novel and more biomimetic approaches for neural TE.

Electroactive Polymers for On-Demand Drug Release

Conductive materials have played a significant role in advancing society into the digital era. Such materials are able to harness the power of electricity and are used to control many aspects of daily life. Conductive polymers (CPs) are an emerging group of polymers that possess metal-like conductivity yet retain desirable polymeric features, such as processability, mechanical properties, and biodegradability. Upon receiving an electrical stimulus, CPs can be tailored to achieve a number of responses, such as harvesting energy and stimulating tissue growth. The recent FDA approval of a CP-based material for a medical device has invigorated their research in healthcare. In drug delivery, CPs can act as electrical switches, drug release is achieved at a flick of a switch, thereby providing unprecedented control over drug release. In this review, recent developments in CP as electroactive polymers for voltage-stimuli responsive drug delivery systems are evaluated. The review demonstrates the distinct drug release profiles achieved by electroactive formulations, and both the precision and ease of stimuli response. This level of dynamism promises to yield "smart medicines" and warrants further research. The review concludes by providing an outlook on electroactive formulations in drug delivery and highlighting their integral roles in healthcare IoT.

Conductive Viologen Hydrogel Based on Hyperbranched Polyamidoamine for Multiple Stimulus-Responsive Drug Delivery

The emergence of precision medicine and personalized pharmacotherapy has led to the development of advanced drug delivery systems that can respond to multiple stimuli. Conductive hydrogels have excellent electrical signal responsiveness and drug storage capabilities; however, current conductive hydrogels suffer from poor mechanical properties, low ionic conductivity, and high voltage. Herein, a covalently crosslinked viologen hydrogel was prepared using electroactive hyperbranched polyamidoamine (EHP) as the crosslinking center in a polymeric network. Attributed to its unique molecular architecture, this hydrogel exhibits improved mechanical properties (high tensile strength and desirable stretchability up to 1280%). Approvable ionic conductivity, biocompatibility, antibacterial properties, and wearable strain-sensing performance were also disclosed, ascribed to the participation of versatile viologen groups in the hydrogel structure. This hydrogel exhibited high efficiency in drug release (81.6%) at a lower voltage of -1.2 V. Moreover, fascinating pH-stimulus drug release behavior was also demonstrated in both acidic and alkalescent environments owing to the dramatic conformational transition of EHP. This work provides a new design strategy for conductive hydrogels for multiple stimulus-responsive drug delivery systems.

Current Progress in Conductive Hydrogels and Their Applications in Wearable Bioelectronics and Therapeutics

Wearable bioelectronics and therapeutics are a rapidly evolving area of research, with researchers exploring new materials that offer greater flexibility and sophistication. Conductive hydrogels have emerged as a promising material due to their tunable electrical properties, flexible mechanical properties, high elasticity, stretchability, excellent biocompatibility, and responsiveness to stimuli. This review presents an overview of recent breakthroughs in conductive hydrogels, including their materials, classification, and applications. By providing a comprehensive review of current research, this paper aims to equip researchers with a deeper understanding of conductive hydrogels and inspire new design approaches for various healthcare applications.