An injectable hydrogel based on hyaluronic acid prepared by Schiff base for long-term controlled drug release

Hydrogel-based 3D printing technology: From interfacial engineering to precision medicine

Advances in 3D printing technology and the development of hydrogel-based inks have significantly enhanced the potential of precision medicine, promoting progress in medical diagnosis and treatment. The development of 3D printing enables the fabrication of complex gradient structures that emulate natural tissue environments, while advancements in interface engineering facilitate the precise control of interface properties, thereby enhancing the performance of hydrogels in biomedical applications. This review focuses on the latest advancements in three critical 3D printing application areas: efficient real-time detection, drug delivery systems, and regenerative medicine. The application of 3D printing technology enhances nucleic acid-based molecular diagnostic platforms and wearable biosensors for real-time monitoring of physiological parameters, thereby providing robust support for early disease diagnosis. Additionally, it facilitates the development of targeted and controlled drug delivery systems, which offer promising methods for efficient drug utilization, and enables the construction of complex tissue and organ structures with bioactivity and functionality, providing new solutions for regenerative medicine. Collectively, these advancements propel the ongoing progress and development of precision medicine. Furthermore, the challenges associated with 3D printing technology in these three major applications are discussed along with an outlook on prospects.

Intraocular injectable hydrogels for the delivery of cells and nanoparticles

The rising global life expectancy has led to a growing prevalence of ophthalmic diseases, while current treatments face important limitations in terms of efficacy, costs, and patient compliance. The use of injectable hydrogels as drug and cell carriers is a promising approach, compared to the injection of drug solutions or cell suspensions. This is because the hydrogel matrix may offer protection against clearance or degradation, may modulate drug/cell release, and provide a biomimetic substrate for differentiating cells while being minimally invasive. On one hand, injectable hydrogels for ocular drug delivery have been traditionally designed to host and release small drugs or proteins. However, limitations such as high burst release and difficulty of entrapping hydrophobic molecules led to the emergence of nanocomposite hydrogels, where the drug is entrapped in nanoparticles prior hydrogel incorporation. Composite systems offer great advantages over the injection of particle suspensions, improving particle fate and drug release kinetics. On the other hand, injectable hydrogels offer a cell-friendly environment to seek tissue regeneration, providing biomechanical and biochemical cues for cellular cross-talk, differentiation, and formation of new extracellular matrix. This review critically discusses recent advancements in the development of novel injectable hydrogels as delivery vehicles for drug-loaded nanoparticles and cells, with a major focus on the formulation components, administration routes, and other factors affecting performance, highlighting promising aspects and challenges to address in the future.

Aldehyde-functionalization of chitin nanocrystals via SI-ARGET ATRP of lignin-derived monomers

Chitin nanocrystals (ChNCs), prepared from a down-sizing process from chitin, have recently captured great attention to access sustainable nanomaterials. The surface modification of ChNCs is crucial to regulate the surface physicochemical properties and introduce specific functions, thus satisfying their diverse applications. In this study, aldehyde-functionalized ChNCs (ChNCs-PVMA) with enhanced hydrophobicity were developed via surface-initiated activators regenerated by electron transfer for atom transfer radical polymerization (SI-ARGET ATRP) of a lignin-derived polymerizable aldehyde monomer, vanillin methacrylate (VMA). The monomer conversion was determined by 1H NMR spectroscopy of the reaction mixture based on the change of the relative ratio of VMA and solvent signals. The prepared ChNCs-PVMA were systematically characterized by FTIR, CP/MAS 13C NMR, XPS, XRD, DSC, TGA, and TEM. The dispersibility of ChNCs and ChNCs-PVMA in water and DMF was evaluated by dynamic light scattering and visual observation, indicating good dispersion of ChNCs-PVMA in organic solvents. Furthermore, based on the available aldehyde groups, the ChNCs-PVMA was reacted with amino acids via Schiff base reaction, demonstrating a rich follow-up chemistry towards diverse functions by the reactive aldehyde groups.

Ferric ions crosslinked hyaluronic acid beads: potentials for drug delivery use

INTRODUCTION AND PURPOSE

Despite the attractive properties of hyaluronic acid (HA), The preparation of HA beads is still challenging. This article reports the preparation of pH-sensitive gel HA beads. The ionic gelation method was used to prepare the HA gel beads using ferric ions. This cross-linking type is based on forming coordination bonds, which enhance the mechanical properties of the prepared beads.

METHODS

The developed beads were characterized using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) examined the bead's morphology. Furthermore, the potential of HA gel beads as an oral drug delivery system was investigated using metformin as a hydrophilic model drug. The entrapment efficiency and in vitro, release, and release kinetics were evaluated. The crosslinking density and HA concentration effect on drug release and bead swelling capacity under pH 1.2 and 7.4 were also investigated.

RESULTS

The entrapment efficiency of metformin in HA beads was found to be 79.56 ± 3.89%. FTIR analysis indicated the ionic interaction between ferric ions and the carboxylic groups on the HA molecule. At the same time, there was no substantial interaction between metformin and the polymeric bead. Morphological evaluation and DSC analysis suggested the successful incorporation of metformin within the beads. The in vitro drug release evaluation showed pH-dependent extended release where the release kinetics followed the first-order mathematical model.

CONCLUSIONS

This study provides a value-added formulation with the potential for drug delivery use, which can be further investigated for biomedical applications.

Intra-articular injection of platinum nanozyme-loaded silk fibroin/pullulan hydrogels relieves osteoarthritis through ROS scavenging and ferroptosis suppression

Reactive oxygen species (ROS)-mediated ferroptosis plays a critical role in the development of osteoarthritis (OA). Consequently, it is speculated that anti-ferroptosis agents could represent a novel therapeutic strategy for managing OA. In this study, a hydrogel incorporating platinum (Pt) nanozyme was synthesized by dispersing Pt nanoparticles (NPs) within a matrix of silk fibroin (SF) and oxidized pullulan (oxPL). This hydrogel allows for a substantial and sustained release of up to 30 days. The gelation time (from 140.3 ± 42.3 s to 460.0 ± 40.0 s), swelling capacity (from 57.7 ± 3.8 % to 24.0 ± 7.0 %), and degradation rate (from 60.3 ± 4.7 % to 32.0 ± 4.6 %) of the hydrogels can be modulated by adjusting the Pt NP content. The Pt@SF/oxPL hydrogel effectively eliminates ROS due to its catalase-like and superoxide dismutase-like enzymatic properties. In vitro studies demonstrated that Pt@SF/oxPL efficiently mitigated the process of ferroptotic cell death in chondrocytes. More critically, intra-articular administration of Pt@SF/oxPL showcased therapeutic advantages by both protecting and stimulating the regeneration of cartilage throughout the progression of OA. Collectively, this study suggests that Pt@SF/oxPL hydrogels could potentially serve as an effective treatment for OA, presenting a novel nanozyme-based therapeutic approach for this condition.

A polysaccharide from Periplaneta americana promotes macrophage M2 polarization, exhibiting anti-inflammatory and wound-healing activities

A miscellaneous polysaccharide, PAP55-3-1, with a molecular weight of 23.03 kDa, was isolated from Periplaneta americana through extraction with dilute alkali solution, ethanol precipitation, and column chromatography purification. Structural analysis shows that PAP55-3-1 is mainly composed of five monosaccharides: galactosamine hydrochloride, glucosamine hydrochloride, galactose, glucose and mannose. Its main glycosidic bonds are: Manp-(1→, Galp-(1→, →3)-Galp-(1→, →3,6)-Manp-(1→, →2,6)-Manp-(1→, →6)-Manp-(1→, →4)-Galp-(1→, →6-Glcp-(1→, →6)-Galp-(1→, →2)-Manp-(1 →, →3,4)-Glcp-(1→, →3,6)-Galp-(1→. In vitro experiments demonstrated that PAP55-3-1 can effectively inhibit reactive oxygen species (ROS) and O2- production following H2O2-induction. After H2O2-induction, HIF-1α (hypoxia-inducible factor) was translocated in mitochondria PAP55-3-1 increased localization of HIF-1α was located on mitochondria to maintain the stability of mitochondrial function stability, thereby effectively inhibiting H2O2-induced mitochondrial oxidative damage. Additionally, PAP55-3-1 inhibited the M1 polarization of macrophages stimulated by H2O2 and promoted the phenotype polarization of macrophages from M1 to M2, displaying anti-inflammatory and pro-repair properties. In vivo experimental results indicated that PAP55-3-1 promoted wound healing in mice. Immunohistochemical experiments revealed a reduction in CD68 expression and increase in CD206 expression in both positive and the high-dose polysaccharide group control group. This further demonstrated that PAP55-3-1 promotes the phenotype polarization of macrophages from M1 to M2, exerting anti-inflammatory and wound-healing activities.

Schiff base crosslinked hyaluronic acid hydrogels with tunable and cell instructive time-dependent mechanical properties

The dynamic interplay between cells and their native extracellular matrix (ECM) influences cellular behavior, imposing a challenge in biomaterial design. Dynamic covalent hydrogels are viscoelastic and show self-healing ability, making them a potential scaffold for recapitulating native ECM properties. We aimed to implement kinetically and thermodynamically distinct crosslinkers to prepare self-healing dynamic hydrogels to explore the arising properties and their effects on cellular behavior. To do so, aldehyde-substituted hyaluronic acid (HA) was synthesized to generate imine, hydrazone, and oxime crosslinked dynamic covalent hydrogels. Differences in equilibrium constants of these bonds yielded distinct properties including stiffness, stress relaxation, and self-healing ability. The effects of degree of substitution (DS), polymer concentration, crosslinker to aldehyde ratio, and crosslinker functionality on hydrogel properties were evaluated. The self-healing ability of hydrogels was investigated on samples of the same and different crosslinkers and DS to obtain hydrogels with gradient properties. Subsequently, human dermal fibroblasts were cultured in 2D and 3D to assess the cellular response considering the dynamic properties of the hydrogels. Moreover, assessing cell spreading and morphology on hydrogels having similar modulus but different stress relaxation rates showed the effects of matrix viscoelasticity with higher cell spreading in slower relaxing hydrogels.

Injectable hydrogels based on biopolymers for the treatment of ocular diseases

Injectable hydrogels based on biopolymers, fabricated utilizing diverse chemical and physical methodologies, exhibit exceptional physical, chemical, and biological properties. They have multifaceted applications encompassing wound healing, tissue regeneration, and across diverse scientific realms. This review critically evaluates their largely uncharted potential in ophthalmology, elucidating their diverse applications across an array of ocular diseases. These conditions include glaucoma, cataracts, corneal disorders (spanning from age-related degeneration to trauma, infections, and underlying chronic illnesses), retina-associated ailments (such as diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration (AMD)), eyelid abnormalities, and uveal melanoma (UM). This study provides a thorough analysis of applications of injectable hydrogels based on biopolymers across these ocular disorders. Injectable hydrogels based on biopolymers can be customized to have specific physical, chemical, and biological properties that make them suitable as drug delivery vehicles, tissue scaffolds, and sealants in the eye. For example, they can be engineered to have optimum viscosity to be injected intravitreally and sustain drug release to treat retinal diseases. Their porous structure and biocompatibility promote cellular infiltration to regenerate diseased corneal tissue. By accentuating their indispensable role in ocular disease treatment, this review strives to present innovative and targeted approaches in this domain, thereby advancing ocular therapeutics.

Hyaluronic acid-based multifunctional bio-active coating integrated with cinnamaldehyde/hydroxypropyl-β-cyclodextrin inclusion complex for fruit preservation

Natural preservatives such as cinnamaldehyde (CIN) are garnering increasing interest to replace their synthetic counterparts in maintaining fruit freshness and safety. However, their long-term effectiveness and widespread application have been greatly limited due to high volatility and potent aroma. To address these challenges, we developed a viable and simple strategy to prepare a multifunctional active coating for fruit preservation by incorporating host-guest inclusion complex of CIN and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) CIN@HP-β-CD into hyaluronic acid (HA), a natural polysaccharide with exceptional film-forming properties. The as-prepared HA/CIN@HP-β-CD coatings exhibited universal surface affinity, excellent antimicrobial performance, and satisfactory antioxidant properties with no potential toxicity. Release kinetic studies have demonstrated that CIN in the coating is continuously and slowly released. Furthermore, freshness preservation experiments on bananas and fresh-cut apples demonstrated that the developed coating is effective in preserving the color of fruit, decreasing the weight loss rate, preventing the microorganism's growth, and significantly extending the period of freshness, exhibiting the potential for application in fruit preservation.

Injectable, stable, and biodegradable hydrogel with platelet-rich plasma induced by l-serine and sodium alginate for effective treatment of intrauterine adhesions

The combination of pharmacological and physical barrier therapy is a highly promising strategy for treating intrauterine adhesions (IUAs), but there lacks a suitable scaffold that integrates good injectability, proper mechanical stability and degradability, excellent biocompatibility, and non-toxic, non-rejection therapeutic agents. To address this, a novel injectable, degradable hydrogel composed of poly(ethylene glycol) diacrylate (PEGDA), sodium alginate (SA), and l-serine, and loaded with platelet-rich plasma (PRP) (referred to as PSL-PRP) is developed for treating IUAs. l-Serine induces rapid gelation within 1 min and enhances the mechanical properties of the hydrogel, while degradable SA provides the hydrogel with strength, toughness, and appropriate degradation capabilities. As a result, the hydrogel exhibits an excellent scaffold for sustained release of growth factors in PRP and serves as an effective physical barrier. In vivo testing using a rat model of IUAs demonstrates that in situ injection of the PSL-PRP hydrogel significantly reduces fibrosis and promotes endometrial regeneration, ultimately leading to fertility restoration. The combined advantages make the PSL-PRP hydrogel very promising in IUAs therapy and in preventing adhesions in other internal tissue wounds.

Injectable long-acting formulations (ILAFs) and manufacturing techniques

INTRODUCTION

Most therapeutics delivered using short-acting formulations need repeated administration, which can harm patient compliance and raise failure risks related to inconsistent treatment. Injectable long-acting formulations (ILAFs) are controlled/sustained-release formulations fabricated to deliver active pharmaceutical ingredients (APIs) and extend their half-life over days to months. Longer half-lives of ILAFs minimize the necessity for frequent doses, increase patient compliance, and reduce the risk of side effects from intravenous (IV) infusions. Using ILAF technologies, the immediate drug release can also be controlled, thereby minimizing potential adverse effects due to high initial drug blood concentrations.

AREA COVERED

In this review, we have discussed various ILAFs, their physiochemical properties, fabrication technologies, advantages, and practical issues, as well as address some major challenges in their application. Especially, the approved ILAFs are highlighted.

EXPERT OPINION

ILAFs are sustained-release formulations with extended activity, which can improve patient compliance. ILAFs are designed to deliver APIs like proteins and peptides and extend their half-life over days to months. The specific properties of each ILAF preparation, such as extended-release and improved drug targeting capabilities, make them an effective approach for precise and focused therapy. Furthermore, this is especially helpful for biopharmaceuticals with short biological half-lives and low stability since most environmental conditions can protect them from sustained-release delivery methods.

Preparation and Characterization of a Novel Longzhua mushroom Polysaccharide Hydrogel and Slow-Release Behavior of Encapsulated Rambutan Peel Polyphenols

Natural polyphenols have drawbacks such as instability and low bioavailability, which can be overcome by encapsulated slow-release systems. Natural polymer hydrogels are ideal materials for slow-release systems because of their high biocompatibility. In this study, Longzhua mushroom polysaccharide hydrogel (LMPH) was used to encapsulate rambutan peel polyphenols (RPP) and delay their release time to improve their stability and bioavailability. The mechanical properties, rheology, stability, swelling properties, water-holding capacity, RPP loading, and slow-release behavior of LMPH were investigated. The results showed that LMPH has adequate mechanical and rheological properties, high thermal stability, excellent swelling and water-holding capacity, and good self-healing behavior. Increasing the polysaccharide content not only improved the hardness (0.17-1.13 N) and water-holding capacity of LMPH (90.84-99.32%) but also enhanced the encapsulation efficiency of RPP (93.13-99.94%). The dense network structure slowed down the release of RPP. In particular, LMPH5 released only 61.58% at 48 h. Thus, a stable encapsulated slow-release system was fabricated using a simple method based on the properties of LMPH. The developed material has great potential for the sustained release and delivery of biologically active substances.

Synthesis and Properties of Injectable Hydrogel for Tissue Filling

Hydrogels with injectability have emerged as the focal point in tissue filling, owing to their unique properties, such as minimal adverse effects, faster recovery, good results, and negligible disruption to daily activities. These hydrogels could attain their injectability through chemical covalent crosslinking, physical crosslinking, or biological crosslinking. These reactions allow for the formation of reversible bonds or delayed gelatinization, ensuring a minimally invasive approach for tissue filling. Injectable hydrogels facilitate tissue augmentation and tissue regeneration by offering slow degradation, mechanical support, and the modulation of biological functions in host cells. This review summarizes the recent advancements in synthetic strategies for injectable hydrogels and introduces their application in tissue filling. Ultimately, we discuss the prospects and prevailing challenges in developing optimal injectable hydrogels for tissue augmentation, aiming to chart a course for future investigations.

Hydrogels in Ophthalmology: Novel Strategies for Overcoming Therapeutic Challenges

The human eye's intricate anatomical and physiological design necessitates tailored approaches for managing ocular diseases. Recent advancements in ophthalmology underscore the potential of hydrogels as a versatile therapeutic tool, owing to their biocompatibility, adaptability, and customizability. This review offers an exploration of hydrogel applications in ophthalmology over the past five years. Emphasis is placed on their role in optimized drug delivery for the posterior segment and advancements in intraocular lens technology. Hydrogels demonstrate the capacity for targeted, controlled, and sustained drug release in the posterior segment of the eye, potentially minimizing invasive interventions and enhancing patient outcomes. Furthermore, in intraocular lens domains, hydrogels showcase potential in post-operative drug delivery, disease sensing, and improved biocompatibility. However, while their promise is immense, most hydrogel-based studies remain preclinical, necessitating rigorous clinical evaluations. Patient-specific factors, potential complications, and the current nascent stage of research should inform their clinical application. In essence, the incorporation of hydrogels into ocular therapeutics represents a seminal convergence of material science and medicine, heralding advancements in patient-centric care within ophthalmology.