Hybrid Shear-thinning Hydrogel Integrating Hyaluronic Acid with ROS-Responsive Nanoparticles

Shear-thinning hydrogel for allograft cell transplantation and externally controlled transgene expression

This work establishes the design of a fully synthetic, shear-thinning hydrogel platform that is injectable and can isolate engineered, allogeneic cell therapies from the host. We utilized RAFT to generate a library of linear random copolymers of N,N-dimethylacrylamide (DMA) and 2-vinyl-4,4-dimethyl azlactone (VDMA) with variable mol% VDMA and degree of polymerization. Poly(DMA-co-VDMA) copolymers were subsequently modified with either adamantane (Ad) or β-cyclodextrin (Cd) through amine-reactive VDMA to prepare hydrogel precursor macromers containing complementary guest-host pairing pendant groups that, when mixed, form shear-thinning hydrogels. Rheometric evaluation of the hydrogel library enabled identification of lead macromer structures comprising 15 mol% pendants (Ad or Cd) and a degree of polymerization of 1000; mixing of these Ad and Cd functionalized precursors yielded hydrogels possessing storage modulus above 1000 Pa, tan(δ) values below 1 and high yield strain, which are target characteristics of robust but injectable shear-thinning gels. This modular system proved amenable to nanoparticle integration with surface-modified nanoparticles displaying Ad. The addition of the Ad-functionalized nanoparticles simultaneously improved mechanical properties of the hydrogels and enabled extended hydrogel retention of a model small molecule in vivo. In studies benchmarking against alginate, a material traditionally used for cell encapsulation, the lead hydrogel showed significantly less fibrous encapsulation in a subcutaneous implant site. Finally, this platform was utilized to encapsulate and extend in vivo longevity of inducible transgene-engineered mesenchymal stem cells in an allogeneic transplant model. The hydrogels remained intact and blocked infiltration by host cells, consequently extending the longevity of grafted cell function relative to a benchmark, shear-thinning hyaluronic acid-based gel. In sum, the new synthetic, shear-thinning hydrogel system presented here shows potential for further development as an injectable platform for delivery and in situ drug modulation of allograft and engineered cell therapies.

Reactive oxygen species (ROS)-responsive biomaterials for treating myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is a critical issue that arises when restoring blood flow after an ischemic event in the heart. Excessive reactive oxygen species (ROS) production during this process exacerbates cellular damage and impairs cardiac function. Recent therapeutic strategies have focused on leveraging the ROS microenvironment to design targeted drug delivery systems. ROS-responsive biomaterials have emerged as promising candidates, offering enhanced therapeutic efficacy with reduced systemic adverse effects. This review examines the mechanisms of ROS overproduction during myocardial ischemia-reperfusion and summarizes significant advancements in ROS-responsive biomaterials for MIRI treatment. We discuss various chemical strategies to impart ROS sensitivity to these materials, emphasizing ROS-induced solubility switches and degradation mechanisms. Additionally, we highlight various ROS-responsive therapeutic platforms, such as nanoparticles and hydrogels, and their unique advantages in drug delivery for MIRI. Preclinical studies demonstrating the efficacy of these materials in mitigating MIRI in animal models are reviewed, alongside their mechanisms of action and potential clinical implications. We also address the challenges and future prospects of translating these state of the art biomaterial-based therapeutics into clinical practice to improve MIRI management and cardiac outcomes. This review will provide valuable insights for researchers and clinicians working on novel therapeutic strategies for MIRI intervention.

Temperature-Regulated Synthesis of Hyaluronic Acid-Interpenetrated Polyacrylamide/Poly(Acrylic Acid Sodium Salt) Semi-Interpenetrated Polymer Network Gel for the Removal of Methyl Violet

An alternative synthetic pathway was proposed for the optimization of synthesis to find a better correlation between the swelling and elasticity of hyaluronic acid-interpenetrated gels via temperature regulation. An experimental design methodology was presented for the synthesis of polyacrylamide/poly(acrylic acid sodium salt)/hyaluronic acid, PAAm/PSA/HyA, gels by modifying the one-pot procedure using free radical crosslinking copolymerization of AAm with the addition of anionic linear PSA chains in the presence of various amount of HyA, ranging between 0.05% and 0.20% (w/v). Semi-interpenetrated polymer network (IPN)-structured gels were designed with tunable elasticity, in which the extent of covalent crosslinking interactions is controlled by polymerization temperature ranging between -18 and 45 °C. Depending on the HyA content added in the synthesis and the polymerization temperature, the swelling ratio could be controlled. The addition of 0.05% (w/v) HyA increased the swelling of semi-IPNs, while the elastic modulus increased with increasing HyA content and decreased with the polymerization temperature. PAAm/PSA/HyA semi-IPNs showed the typical pH-sensitive swelling of anionic gels, and the swelling reached a maximum at a pH of 11.2. PAAm/PSA/HyA gels were tested for the removal of methyl violet from wastewater. Adsorption kinetics were shown to be well-fitted with the pseudo-second-order model using linear and nonlinear regression analysis. With the clear relationship between increased modulus and composition, this study enabled the fine-tuning of semi-IPN interactions by varying the polymerization temperature.

Hybrid Nanoparticle-Hydrogel Systems for Drug Delivery Depots and Other Biomedical Applications

Hydrogel-based depots typically tend to remain where injected and have excellent biocompatibility but are relatively poor at controlling drug release. Nanoparticles (NPs) typically have the opposite properties. The smaller the NPs are, the more likely they are to leave the site of injection. Their biocompatibility is variable depending on the material but can be poor. However, NPs can be good at controlling drug release. In these and other properties, combining NPs and hydrogels can leverage their advantages and negate their disadvantages. This review highlights the rationale for hybrid NP-hydrogel systems in drug delivery, the basic methods of producing them, and examples where combining the two systems addressed specific problems.

ROS-responsive hydrogels: from design and additive manufacturing to biomedical applications

Hydrogels with intricate 3D networks and high hydrophilicity have qualities resembling those of biological tissues, making them ideal candidates for use as smart biomedical materials. Reactive oxygen species (ROS) responsive hydrogels are an innovative class of smart hydrogels, and are cross-linked by ROS-responsive modules through covalent interactions, coordination interactions, or supramolecular interactions. Due to the introduction of ROS response modules, this class of hydrogels exhibits a sensitive response to the oxidative stress microenvironment existing in organisms. Simultaneously, due to the modularity of the ROS-responsive structure, ROS-responsive hydrogels can be manufactured on a large scale through additive manufacturing. This review will delve into the design, fabrication, and applications of ROS-responsive hydrogels. The main goal is to clarify the chemical principles that govern the response mechanism of these hydrogels, further providing new perspectives and methods for designing responsive hydrogel materials.

Hyaluronic acid-conjugated methotrexate and 5-fluorouracil for targeted drug delivery

The delivery of chemotherapeutical drugs via nanomaterials has become a focus of pharmaceutical research over several decades due to improved drug delivery to cancer cells, decreased side effects on normal tissues, and increased therapeutic efficacy. Herein, a novel hyaluronic acid-conjugated methotrexate and 5-fluorouracil nanodrug system has been developed to address the critical limitations associated with the high toxicity and side effects of methotrexate and 5-fluorouracil. Furthermore, this nanodrug system enhances the targeting capacity of drug molecules and facilitates the potential integration of multimodal drug therapies. Concomitantly, the synergistic effects of MTX with 5-fluorouracil have been shown to improve the therapeutic index of MTX while attenuating the associated toxicities of MTX. The structure and micromorphology of the novel nanodrug can be confirmed by 1HNMR, FT-IR, UV-Vis, DLS, TEM, and AFM. Due to the ability of HA to bind to CD44 receptors activated on the surface of cancer cells and its enhanced permeability and retention (EPR) effect, the novel nanodrug we designed and synthesized can effectively target cancer cells. Cell counting Kit-8 (CCK8), flow cytometry, and live-dead staining assays in vitro showed that this nanodrug system had high targeting and antitumor activity against CD44 receptors. By using drugs to act on patient-derived colorectal, liver, and breast cancer organoids, the anticancer effect of the nanodrug was identified and verified. These results showed that the nanodrug system developed in this study may have great potential as a targeted therapy for cancer.

Antioxidant Hydrogels: Antioxidant Mechanisms, Design Strategies, and Applications in the Treatment of Oxidative Stress-Related Diseases

Oxidative stress is a biochemical process that disrupts the redox balance due to an excess of oxidized substances within the cell. Oxidative stress is closely associated with a multitude of diseases and health issues, including cancer, diabetes, cardiovascular diseases, neurodegenerative disorders, inflammatory conditions, and aging. Therefore, the developing of antioxidant treatment strategies has emerged as a pivotal area of medical research. Hydrogels have garnered considerable attention due to their exceptional biocompatibility, adjustable physicochemical properties, and capabilities for drug delivery. Numerous antioxidant hydrogels have been developed and proven effective in alleviating oxidative stress. In the pursuit of more effective treatments for oxidative stress-related diseases, there is an urgent need for advanced strategies for the fabrication of multifunctional antioxidant hydrogels. Consequently, the authors' focus will be on hydrogels that possess exceptional reactive oxygen species and reactive nitrogen species scavenging capabilities, and their role in oxidative stress therapy will be evaluated. Herein, the antioxidant mechanisms and the design strategies of antioxidant hydrogels and their applications in oxidative stress-related diseases are discussed systematically in order to provide critical insights for further advancements in the field.

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.

Engineered cyclodextrin-based supramolecular hydrogels for biomedical applications

Cyclodextrin (CD)-based supramolecular hydrogels are polymer network systems with the ability to rapidly form reversible three-dimensional porous structures through multiple cross-linking methods, offering potential applications in drug delivery. Although CD-based supramolecular hydrogels have been increasingly used in a wide range of applications in recent years, a comprehensive description of their structure, mechanical property modulation, drug loading, delivery, and applications in biomedical fields from a cross-linking perspective is lacking. To provide a comprehensive overview of CD-based supramolecular hydrogels, this review systematically describes their design, regulation of mechanical properties, modes of drug loading and release, and their roles in various biomedical fields, particularly oncology, wound dressing, bone repair, and myocardial tissue engineering. Additionally, this review provides a rational discussion on the current challenges and prospects of CD-based supramolecular hydrogels, which can provide ideas for the rapid development of CD-based hydrogels and foster their translation from the laboratory to clinical medicine.