Rutin-Loaded Stimuli-Responsive Hydrogel for Anti-Inflammation

pH-Responsive injectable self-healing hydrogels loading Au nanoparticles-decorated bimetallic organic frameworks for synergistic sonodynamic-chemodynamic-starvation-chemo therapy of cancer

A novel and efficient cancer therapy was developed using a smart hydrogel containing multifunctional bimetallic organic frameworks and anticancer drugs. The injectable self-healing hydrogel with pH-responsiveness was constructed through borate ester and imine bonds among dopamine-grafted sodium alginate (SADA), hydroxypropyl chitosan (HPCS) and 2-formylphenylboronic acid (2-FPBA). The Au nanoparticles-decorated Ti/Fe bimetallic organic framework tetragonal nanosheets (Au/TF-MOF TNS) were synthesized and incorporated into the hydrogel with the anticancer drugs doxorubicin (DOX). Upon intratumoral injection of nanocomposite hydrogel, the acidic tumor microenvironment triggered the cleavage of borate ester and imine bonds, causing the hydrogel to break down and accelerating the release of both Au/TF-MOF TNS and DOX. These Au/TF-MOF TNS functioned as nanozymes, producing hydroxyl radicals (·OH) for chemodynamic therapy (CDT), generating oxygen (O2) to support sonodynamic therapy (SDT), and depleting glucose for starvation therapy (ST). Additionally, the Au/TF-MOF TNS served as sonosensitizers, capable of converting O2 into singlet oxygen (1O2) upon ultrasound irradiation to achieve SDT. Therefore, this nanocomposite hydrogel system enabled synergistic sonodynamic-chemodynamic-starvation-chemo therapy (SDT-CDT-ST-CT) of cancer, presenting a promising platform for advanced cancer therapy strategies.

Effect of hydrogel drug delivery system for treating ulcerative colitis: A preclinical meta-analysis

Hydrogel drug delivery systems (DDSs) for treating ulcerative colitis (UC) have garnered attention. However, there is a lack of meta-analysis summarizing their effectiveness. Therefore, this study aimed to conduct a meta-analysis of pre-clinical evidence comparing hydrogel DDSs with free drug administration. Subgroup analyses were performed based on hydrogel materials (polysaccharide versus non-polysaccharide) and administration routes of the hydrogel DDSs (rectal versus oral). The outcome indicators included colon length, histological scores, tumor necrosis factor-α (TNF-α), zonula occludens protein 1(ZO-1), and area under the curve (AUC). The results confirmed the therapeutic enhancement of the hydrogel DDSs for UC compared with the free drug group. Notably, no significant differences were found between polysaccharide and non-polysaccharide materials, however, oral administration was found superior regarding TNF-α and AUC. In conclusion, oral hydrogel DDSs can serve as potential excellent dosage forms in oral colon -targeting DDSs, and in the design of colon hydrogel delivery systems, polysaccharides do not show advantages compared with other materials.

Soft Actuators and Actuation: Design, Synthesis, and Applications

Soft actuators are one of the most promising technological advancements with potential solutions to diverse fields' day-to-day challenges. Soft actuators derived from hydrogel materials possess unique features such as flexibility, responsiveness to stimuli, and intricate deformations, making them ideal for soft robotics, artificial muscles, and biomedical applications. This review provides an overview of material composition and design techniques for hydrogel actuators, exploring 3D printing, photopolymerization, cross-linking, and microfabrication methods for improved actuation. It examines applications of hydrogel actuators in biomedical, soft robotics, bioinspired systems, microfluidics, lab-on-a-chip devices, and environmental, and energy systems. Finally, it discusses challenges, opportunities, advancements, and regulatory aspects related to hydrogel actuators.

Dynamic hydrogel-metal-organic framework system promotes bone regeneration in periodontitis through controlled drug delivery

Periodontitis is a prevalent chronic inflammatory disease, which leads to gradual degradation of alveolar bone. The challenges persist in achieving effective alveolar bone repair due to the unique bacterial microenvironment's impact on immune responses. This study explores a novel approach utilizing Metal-Organic Frameworks (MOFs) (comprising magnesium and gallic acid) for promoting bone regeneration in periodontitis, which focuses on the physiological roles of magnesium ions in bone repair and gallic acid's antioxidant and immunomodulatory properties. However, the dynamic oral environment and irregular periodontal pockets pose challenges for sustained drug delivery. A smart responsive hydrogel system, integrating Carboxymethyl Chitosan (CMCS), Dextran (DEX) and 4-formylphenylboronic acid (4-FPBA) was designed to address this problem. The injectable self-healing hydrogel forms a dual-crosslinked network, incorporating the MOF and rendering its on-demand release sensitive to reactive oxygen species (ROS) levels and pH levels of periodontitis. We seek to analyze the hydrogel's synergistic effects with MOFs in antibacterial functions, immunomodulation and promotion of bone regeneration in periodontitis. In vivo and in vitro experiment validated the system's efficacy in inhibiting inflammation-related genes and proteins expression to foster periodontal bone regeneration. This dynamic hydrogel system with MOFs, shows promise as a potential therapeutic avenue for addressing the challenges in bone regeneration in periodontitis.

In-Bath 3D Printing of Anisotropic Shape-Memory Cryogels Functionalized with Bone-Bioactive Nanoparticles

Cryogels exhibit unique shape memory with full recovery and structural stability features after multiple injections. These constructs also possess enhanced cell permeability and nutrient diffusion when compared to typical bulk hydrogels. Volumetric processing of cryogels functionalized with nanosized units has potential to widen their biomedical applications, however this has remained challenging and relatively underexplored. In this study, we report a novel methodology that combines suspension 3D printing with directional freezing for the fabrication of nanocomposite cryogels with configurable anisotropy. When compared to conventional bulk or freeze-dried hydrogels, nanocomposite cryogel formulations exhibit excellent shape recovery (>95%) and higher pore connectivity. Suspension printing, assisted with a prechilled metal grid, was optimized to induce anisotropy. The addition of calcium- and phosphate-doped mesoporous silica nanoparticles into the cryogel matrix enhanced bioactivity toward orthopedic applications without hindering the printing process. Notably, the nanocomposite 3D printed cryogels exhibit injectable shape memory while also featuring a lamellar topography. The fabrication of these constructs was highly reproducible and exhibited potential for a cell-delivery injectable cryogel with no cytotoxicity to human-derived adipose stem cells. Hence, in this work, it was possible to combine a gravity defying 3D printed methodology with injectable and controlled anisotropic macroporous structures containing bioactive nanoparticles. This methodology ameliorates highly tunable injectable 3D printed anisotropic nanocomposite cryogels with a user-programmable degree of structural complexity.

Effects of charge state of nano-chitin on the properties of polyvinyl alcohol composite hydrogel

The present work investigates the effects of nano-chitin with different charge, obtained by acid hydrolysis and TEMPO oxidation, on the structure and properties of borax crosslinked polyvinyl alcohol (PVA) hydrogels. In detail, nano-chitin prepared by acid hydrolysis (ACh) is positively charged (+28.8 mV). The electrostatic attraction between ACh and borax ions leads to a maximum tensile stress of composite hydrogel (ACh/PB), 54.25 KPa, 17 times of the borax crosslinked PVA (PB). In contrast, nano-chitin prepared by TEMPO-oxidation (TCh) shows negative charge (-59.0 mV). Due to the electrostatic repulsion with borax ions, the maximum tensile stress of composite hydrogel (TCh/PB) is only 9.25 KPa, a very limit reinforcing effect. However, TCh/PB showed better self-healing efficiency (96.0 %) as well as ionic conductivity (1.25 × 10-5 S/m). The present work shows that the charge state of the nano-chitin exerts great influence on the interaction with the crosslinking agent borax, therefore, affects the structure and properties of the final PVA composite hydrogels. The results could provide important information about making full use of nano-chitin as a reinforcement by adjusting its surface charge state.

Fabrication of the Rapid Self-Assembly Hydrogels Loaded with Luteolin: Their Structural Characteristics and Protection Effect on Ulcerative Colitis

Luteolin (LUT) is a fat-soluble flavonoid known for its strong antioxidant and anti-inflammatory properties. Nonetheless, its use in the food industry has been limited due to its low water solubility and bioavailability. In this study, hyaluronic acid, histidine, and luteolin were self-assembled to construct tubular network hydrogels (HHL) to improve the gastrointestinal stability, bioavailability, and stimulation response of LUT. As anticipated, the HHL hydrogel's mechanical strength and adhesion allow it to withstand the challenging gastrointestinal environment and effectively extend the duration of drug presence in the body. In vivo anti-inflammatory experiments showed that HHL hydrogel could successfully alleviate colitis induced by dextran sulfate sodium (DSS) in mice by reducing intestinal inflammation and restoring the integrity of the intestinal barrier. Moreover, HHL hydrogel also regulated the intestinal microorganisms of mice and promoted the production of short-chain fatty acids. The HHL hydrogel group demonstrated a notably superior treatment effect compared to the LUT group alone. The hydrogel delivery system is a novel method to improve the absorption of LUT, increasing its bioavailability and enhancing its pharmaceutical effects.

A guanosine/konjac glucomannan supramolecular hydrogel with antioxidant, antibacterial and immunoregulatory properties for cutaneous wound treatment

Developing naturally-derived wound dressing materials with intrinsic therapeutic effects is desirable for the clinical applications. Recently, guanosine-based supramolecular G-quadruplex (G4) hydrogel exhibited great potential in preparing biological materials due to its simple fabrication method and responsive gel networks. However, the weak mechanical properties and the consequent burst release of bioactive molecules restrict its clinical applications. Herein, we found that konjac glucomannan (KGM) with immunoregulatory effect did not affect the self-assembly of G-quadruplexes and thus effectively enhancing the mechanical properties of G4 hydrogel. Aloin, as a model drug, was in situ loaded into gel networks, finally obtaining the G4/Aloin-KGM hydrogel. This hydrogel exhibited porous morphology, swelling ability and hemostatic capability. Boronate bonds in G4 networks and aloin collectively endowed the hydrogel with excellent antioxidant performance. Meanwhile, aloin also provided outstanding in vitro and in vivo bactericidal ability. The wounds treated with this biocompatible hydrogel demonstrated faster regeneration of epithelial and dermal tissues, and the whole wound healing stages were accelerated by promoting collagen deposition, facilitating macrophage polarization towards M2 phenotype, down-regulating the expression level of IL-6, and up-regulating the expression level of IL-10, CD31 and α-SMA.

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

Inflammatory bowel disease (IBD) is a chronic disorder that affects millions of individuals worldwide. However, current drug therapies for IBD are plagued by significant side effects, low efficacy, and poor patient compliance. Consequently, there is an urgent need for novel therapeutic approaches to alleviate IBD. Hydrogels, three-dimensional networks of hydrophilic polymers with the ability to swell and retain water, have emerged as promising materials for drug delivery in the treatment of IBD due to their biocompatibility, tunability, and responsiveness to various stimuli. In this review, we summarize recent advancements in hydrogel-based drug delivery systems for the treatment of IBD. We first identify three pathophysiological alterations that need to be addressed in the current treatment of IBD: damage to the intestinal mucosal barrier, dysbiosis of intestinal flora, and activation of inflammatory signaling pathways leading to disequilibrium within the intestines. Subsequently, we discuss in depth the processes required to prepare hydrogel drug delivery systems, from the selection of hydrogel materials, types of drugs to be loaded, methods of drug loading and drug release mechanisms to key points in the preparation of hydrogel drug delivery systems. Additionally, we highlight the progress and impact of the hydrogel-based drug delivery system in IBD treatment through regulation of physical barrier immune responses, promotion of mucosal repair, and improvement of gut microbiota. In conclusion, we analyze the challenges of hydrogel-based drug delivery systems in clinical applications for IBD treatment, and propose potential solutions from our perspective.

Guanosine-Based Multidrug Strategy Delivery for Synergistic Anti-Inflammation

The development of codelivery approaches for combination therapy is of great significance, especially for natural products that need to be combined to achieve therapeutic effects. Targeted delivery of multiple drugs through a single carrier remains a challenge. Here, a multi-drug-loaded hydrogel, incorporating quercetin, demethyleneberberine, and dencichine, based on a G4-quadruplex was designed and prepared. Catechol drugs were responsively released in a simulated inflammatory pathological environment by a borate ester linkage, while coagulating dencichine encapsulated in the hydrogel was released along with the degradation of assemblies. The multi-drug-loaded codelivery system is expected to enhance the treatment of inflammatory bowel disease through the synergistic effect of the components. The preparation, characteristic, and physicochemical properties of the multi-drug-loaded assembly were depicted by NMR, CD, and TEM. Degradation assays in vitro proved the good biocompatibility and safety of the hydrogel and a potential pathway to injectable administration. The assays of typical inflammatory cytokines, including TNF-α and IL-6, indicated that these can be significantly suppressed by the treatment of the hydrogel. The current work provided a simple strategy to construct a multi-drug-loaded hydrogel carrier, which facilitated synergistic therapy for natural products by a codelivery approach.

A Guanosine-Derived Antitumor Supramolecular Prodrug

The prodrug strategy for its potential to enhance the pharmacokinetic and/or pharmacodynamic properties of drugs, especially chemotherapeutic agents, has been widely recognized as an important means to improve therapeutic efficiency. Irinotecan's active metabolite, 7-ethyl-10-hydroxycamptothecin (SN38), a borate derivative, was incorporated into a G-quadruplex hydrogel (GB-SN38) by the ingenious and simple approach. Drug release does not depend on carboxylesterase, thus bypassing the side effects caused by ineffective activation, but specifically responds to the ROS-overexpressed tumor microenvironment by oxidative hydrolysis of borate ester that reduces serious systemic toxicity from nonspecific biodistribution of SN38. Comprehensive spectroscopy was used to define the structural and physicochemical characteristics of the drug-loaded hydrogel. The GB-SN38 hydrogel's high level of biosafety and notable tumor-suppressive properties were proven in in vitro and in vivo tests.

Supramolecular chitin-based hydrogels with self-adapting and fast-degradation properties for enhancing wound healing

Due to the features of high porosity, high water content, and tunable viscoelasticity, hydrogels have attracted numerous attentions in the promotion of wound closure. However, the lack of abilities to adapt the wounds of complex shapes and prevent postoperative adhesion limits their therapeutic outcomes in wound healing. To address the above challenges, the supramolecular chitin-based (SMCT) hydrogels are created via the host-guest pre-assembly strategy of β-cyclodextrin (βCD) and adamantane (Ad). The reversible host-guest crosslinks endow the SMCT hydrogels with highly dynamic networks, which can better accommodate irregularly shaped wounds compared with the covalent chitin-based hydrogels with similar mechanical properties. In addition, the SMCT hydrogels show rapid in vivo degradability (degradation time ≈ 2 days) due to the enzyme-triggered degradability of chitin, which do not need to be removed from the wounds after service and thus avoid the secondary damage to skin during dressing change. Owing to the hydrophobic cavity of βCD, the SMCT hydrogels can facilitate the load and release of curcumin with anti-inflammatory, antibacterial, and antioxidative activities, thereby significantly improving the wound healing efficiency. This work provides valuable guidance to the design of self-adaptive and fast-degradable hydrogels that hold great potential for enhancing the wound healing in skin and other tissues.

Stimulus-Responsive Hydrogels as Drug Delivery Systems for Inflammation Targeted Therapy

Deregulated inflammations induced by various factors are one of the most common diseases in people's daily life, while severe inflammation can even lead to death. Thus, the efficient treatment of inflammation has always been the hot topic in the research of medicine. In the past decades, as a potential biomaterial, stimuli-responsive hydrogels have been a focus of attention for the inflammation treatment due to their excellent biocompatibility and design flexibility. Recently, thanks to the rapid development of nanotechnology and material science, more and more efforts have been made to develop safer, more personal and more effective hydrogels for the therapy of some frequent but tough inflammations such as sepsis, rheumatoid arthritis, osteoarthritis, periodontitis, and ulcerative colitis. Herein, from recent studies and articles, the conventional and emerging hydrogels in the delivery of anti-inflammatory drugs and the therapy for various inflammations are summarized. And their prospects of clinical translation and future development are also discussed in further detail.

Hydrogel Tissue Bioengineered Scaffolds in Bone Repair: A Review

Large bone defects due to trauma, infections, and tumors are difficult to heal spontaneously by the body's repair mechanisms and have become a major hindrance to people's daily lives and economic development. However, autologous and allogeneic bone grafts, with their lack of donors, more invasive surgery, immune rejection, and potential viral transmission, hinder the development of bone repair. Hydrogel tissue bioengineered scaffolds have gained widespread attention in the field of bone repair due to their good biocompatibility and three-dimensional network structure that facilitates cell adhesion and proliferation. In addition, loading natural products with nanoparticles and incorporating them into hydrogel tissue bioengineered scaffolds is one of the most effective strategies to promote bone repair due to the good bioactivity and limitations of natural products. Therefore, this paper presents a brief review of the application of hydrogels with different gel-forming properties, hydrogels with different matrices, and nanoparticle-loaded natural products loaded and incorporated into hydrogels for bone defect repair in recent years.

Zinc-Rutin Particles Ameliorate DSS-Induced Acute and Chronic Colitis via Anti-inflammatory and Antioxidant Protection of the Intestinal Epithelial Barrier

In patients suffering from inflammatory bowel diseases (IBDs), the immune system is disrupted and the intestinal barrier function is compromised. Here, six zinc-flavonoid particles were produced by one-step reaction via changing flavonoids (myricetin, quercetin, and rutin) and solvent (water and ethanol), and then their cytocompatibility and ability to scavenge H2O2, free radicals, and LPS-induced ROS were compared. Zinc-rutin particles (W-ZnRT) composed of rutin (78.92 wt %), Na12[ZnPO4]12·12H2O (6.76 wt %), and crystal water were screened out because W-ZnRT exhibited 80.8 ± 15% cell viability against RAW264.7, could rapidly scavenge 78.1 ± 1% of H2O2 and 71.6 ± 2% of DPPH within 30 min, and reduced LPS-increased intracellular ROS to normal levels. In addition, the therapeutic effects of rutin and W-ZnRT were also compared in dextran sulfate sodium (DSS)-induced acute and chronic colitis in mice. W-ZnRT was superior to rutin alone in chronic colitis (n = 9), although they were equally effective in acute colitis (n = 7). Compared to rutin, 11 oral doses of W-ZnRT (40 mg kg-1) significantly improved intestinal permeability (p = 0.0299) and colon length (p = 0.0025), reduced intestinal proinflammatory factors (IL-6, IL-1β, and TNF-α), and upregulated tight junction proteins to maintain intestinal barrier function. Taken together, these results identified W-ZnRT as an efficient and safe therapeutic strategy for IBD.

Oral hydrogel nanoemulsion co-delivery system treats inflammatory bowel disease via anti-inflammatory and promoting intestinal mucosa repair

BACKGROUND

Due to oral nano-delivery systems for the treatment of inflammatory bowel disease (IBD) are often failed to accumulated to the colonic site and could not achieve controlled drug release, it's urgent to develop a microenvironment responsive drug delivery to improve therapy efficacy. Inflammation at the IBD site is mainly mediated by macrophages, which are the key effector cells. Excessive inflammation leads to oxidative stress and intestinal mucosal damage. The use of curcumin (CUR) and emodin (EMO) together for the treatment of IBD is promising due to their respective anti-inflammatory and intestinal mucosal repair effects. In view of the pH gradient environment of gastrointestinal tract, here we prepared pH-responsive sodium alginate (SA) hydrogel-coated nanoemulsions to co-deliver CUR and EMO (CUR/EMO NE@SA) to achieve controlled drug release and specifically target macrophages of the colon.

RESULTS

In this study, a pH-responsive CUR/EMO NE@SA was successfully developed, in which the CUR/EMO NE was loaded by chitosan and further crosslinked with sodium alginate. CUR/EMO NE@SA had a pH-responsive property and could achieve controlled drug release in the colon. The preparation could significantly alleviate and improve the colon inflammatory microenvironment by decreasing TNF-α and IL-6 expression, increasing IL-10 expression, scavenging reactive oxygen species in macrophages, and by ameliorating the restoration of intestinal mucosal tight junction protein expression. Furthermore, we revealed the molecular mechanism of the preparation for IBD treatment, which might due to the CUR and EMO synergic inhibition of NF-κB to improve the pro-inflammatory microenvironment. Our study provides a new IBD therapy strategy via synergically inhibiting inflammatory, repairing mucosal and clearing ROS by pH-sensitive hydrogel-encapsulated nanoemulsion drug delivery system, which might be developed for other chronic inflammatory disease treatment.

CONCLUSIONS

It's suggested that pH-sensitive hydrogel-coated nanoemulsion-based codelivery systems are a promising combinatorial platform in IBD.

Hydrogels for Mucosal Drug Delivery

Mucosal tissues are often a desirable site of drug action to treat disease and engage the immune system. However, systemically administered drugs suffer from limited bioavailability in mucosal tissues where technologies to enable direct, local delivery to these sites would prove useful. In this Spotlight on Applications article, we discuss hydrogels as an attractive means for local delivery of therapeutics to address a range of conditions affecting the eye, nose, oral cavity, gastrointestinal, urinary bladder, and vaginal tracts. Considering the barriers to effective mucosal delivery, we provide an overview of the key parameters in the use of hydrogels for these applications. Finally, we highlight recent work demonstrating their use for inflammatory and infectious diseases affecting these tissues.

Nanomedicine hybrid and catechol functionalized chitosan as pH-responsive multi-function hydrogel to efficiently promote infection wound healing

The complicated wound repair process caused by microbial infection is still a clinical problem due to antibiotic resistance. Therefore it is necessary to employ the incorporating bioactive molecules in the dressing to solve this problem. Herein, a multifunctional nanocomposite hydrogel (CS-HCA-Icps) with the pathological pH-responsive drug release has been developed to promote the infection-impaired wound healing. CS-HCA-Icps nanocomposite hydrogel composed of catechol-grafted chitosan (CS-HCA) and a curcumin-Fe³⁺ coordination nanoparticles (Icps, CurFe³⁺) exhibits the favorable activities in free radical scavenging, anti-bacterial and anti-inflammatory. The favorable biocompatibility is also demonstrated both in vitro and in vivo experiments. These demonstrate the promoting efficacy of hydrogel in wound healing. In this study, Chitosan (CS) shows excellent biocompatibility and antibacterial properties for tissue repair. After functional modification with HCA, the catechol groups are beneficial to improve antioxidant capacity for wound repair, Moreover, Icps nanomedicine are able to enhance the loaded Cur release in response to the pathological acidic microenvironment at the inflammatory stage of wounds. Thus, the pathological pH-responsive hydrogel integrating anti-bacterial, antioxidant, and anti-inflammatory functions may represent a promising strategy for safe and efficient wound healing, in particular for potential clinical use.

Nucleopeptide-Coupled Injectable Bioconjugated Guanosine-Quadruplex Hydrogel with Inherent Antibacterial Activity

The multicomponent reaction-directed self-assembled hydrogels offer the opportunities to fabricate materials with ubiquitous properties which sometimes are not possible to generate from single components. Therefore, multicomponent-derived hydrogels have enormous applications in biomedical fields, and the number of such systems is increasing day by day. Herein, the multicomponent self-assembly techniques have been employed to develop a biomimetic low-molecular-weight G-quadruplex hydrogel under physiological conditions. The bioconjugation of guanosine, 4-formylphenylboronic acid, and cytosine-functionalized nucleopeptide (NP) is important to generate the multicomponent self-assembled dynamic imino-boronate ester-mediated bioconjugated G-quadruplex hydrogels. Using thioflavin T fluorescence assay, powder X-ray diffraction, and circular dichroism spectroscopic techniques, we confirm the existence of a G-quartet-like structure as the key parameter for the formation of nanofibrillar hydrogels. The multicomponent self-assembled G-quadruplex hydrogel possesses excellent inherent antibacterial activity against a broad range of bacterial species. The in vitro cytocompatibility of the synthesized hydrogel was evaluated on MCF-7 and HEK 293T cell lines to study the biocompatibility of the hydrogel. The proposed injectable, biocompatible, and NP-coupled G-quadruplex hydrogel with inherent antibacterial efficiency holds promising importance to prevent localized bacterial infections.

A simple method for fabricating drugs containing a cis-o-diol structure into guanosine-based supramolecular hydrogels for drug delivery

Supramolecular hydrogels are attractive biomaterials for local drug delivery owing to their excellent self-healing, injectable, biodegradable, and biocompatible properties. However, traditional drug-loading approaches based on non-covalent encapsulation and covalent bonding have shown problems such as rapid or difficult drug release, complex reaction processes, low reaction efficiency, and decreased drug activity. Therefore, there is a need to find a simple and efficient method to load drugs into hydrogels, which possess stable drug release ability without impairing drug efficacy. In this study, we introduce dynamic borate ester bonds via a simple one-pot method to load cis-o-diol-containing drugs into guanosine (G)-based supramolecular hydrogels. The experimental results confirm that the dynamic covalent borate ester bonds are formed based on the cis-o-diol groups of the drug and the G in these hydrogels. Meanwhile, the as-prepared G-based hydrogels not only possess self-healing properties and injectability but also have satisfactory biodegradability and biocompatibility. Additionally, the drug can be released from the G-based hydrogel according to the pH-responsive cleavage of the borate ester bonds without affecting drug activity. Overall, these results indicate that the simple one-pot method of utilizing the dynamic borate bond can provide a valuable reference for the design of hydrogel dosage forms.

Multifunctional hydrogels based on chitosan, hyaluronic acid and other biological macromolecules for the treatment of inflammatory bowel disease: A review

Hydrogel is a three-dimensional network polymer material rich in water. It is widely used in the biomedical field because of its unique physical and chemical properties and good biocompatibility. In recent years, the incidence of inflammatory bowel disease (IBD) has gradually increased, and the disadvantages caused by traditional drug treatment of IBD have emerged. Therefore, there is an urgent need for new treatments to alleviate IBD. Hydrogel has become a potential therapeutic platform. However, there is a lack of comprehensive review of functional hydrogels for IBD treatment. This paper first summarizes the pathological changes in IBD sites. Then, the action mechanisms of hydrogels prepared from chitosan, sodium alginate, hyaluronic acid, functionalized polyethylene glycol, cellulose, pectin, and γ-polyglutamic acid on IBD were described from aspects of drug delivery, peptide and protein delivery, biologic therapies, loading probiotics, etc. In addition, the advanced functions of IBD treatment hydrogels were summarized, with emphasis on adhesion, synergistic therapy, pH sensitivity, particle size, and temperature sensitivity. Finally, the future development direction of IBD treatment hydrogels has been prospected.

Self-assembly hydrogels of therapeutic agents for local drug delivery

Advanced drug delivery systems are of vital importance to enhance therapeutic efficacy. Among various recently developed formulations, self-assembling hydrogels composed of therapeutic agents have shown promising potential for local drug delivery owing to their excellent biocompatibility, high drug-loading efficiency, low systemic toxicity, and sustained drug release behavior. In particular, therapeutic agents self-assembling hydrogels with well-defined nanostructures are beneficial for direct delivery to the target site via injection, not only improving drug availability, but also extending their retention time and promoting cellular uptake. In brief, the self-assembly approach offers better opportunities to improve the precision of pharmaceutical treatment and achieve superior treatment efficacies. In this review, we intend to cover the recent developments in therapeutic agent self-assembling hydrogels. First, the molecular structures, self-assembly mechanisms, and application of self-assembling hydrogels are systematically outlined. Then, we summarize the various self-assembly strategies, including the single therapeutic agent, metal-coordination, enzyme-instruction, and co-assembly of multiple therapeutic agents. Finally, the potential challenges and future perspectives are discussed. We hope that this review will provide useful insights into the design and preparation of therapeutic agent self-assembling hydrogels.