Carboxymethyl chitosan microspheres loaded hyaluronic acid/gelatin hydrogels for controlled drug delivery and the treatment of inflammatory bowel disease

Gelatin-lecithin-F127 gel mediated self-assembly of curcumin vesicles for enhanced wound healing

Curcumin, a principal component of Curcuma longa, has a long history of being used topically for wound healing. However, poor aqueous solubility of curcumin leads to poor topical absorption. Recently, gelatin based gel has been reported to overcome this issue. However, the release of curcumin from gelatin gel in the bioavailable or easily absorbable form is still a challenge. The present study reports the development of a composite gel prepared from gelatin, F127 and lecithin using temperature dependant gelation and loading of curcumin within it. Notably, the composite gel facilitated the release of curcumin entrapped within vesicles of ~400 nm size. Further, the composite gel exhibited increase in the storage modulus or gel strength, stability, pore size and hydrophobicity as compared to only gelatin gel. Finally, wound healing assay in murine model indicated that curcumin delivered through composite gel showed a significantly faster healing as compared to that delivered through organic solvent. This was also validated by histopathological and biochemical analysis showing better epithelization and collagen synthesis in the group dressed with curcumin containing composite gel. In conclusion, composite gel facilitated the release of bioavailable or easily absorbable curcumin which in turn enhanced the wound healing.

Emerging Fabrication Strategies of Hydrogels and Its Applications

Recently, hydrogels have been investigated for the controlled release of bioactive molecules, such as for living cell encapsulation and matrices. Due to their remote controllability and quick response, hydrogels are widely used for various applications, including drug delivery. The rate and extent to which the drugs reach their targets are highly dependent on the carriers used in drug delivery systems; therefore the demand for biodegradable and intelligent carriers is progressively increasing. The biodegradable nature of hydrogel has created much interest for its use in drug delivery systems. The first part of this review focuses on emerging fabrication strategies of hydrogel, including physical and chemical cross-linking, as well as radiation cross-linking. The second part describes the applications of hydrogels in various fields, including drug delivery systems. In the end, an overview of the application of hydrogels prepared from several natural polymers in drug delivery is presented.

Enzyme immobilization in hydrogels: A perfect liaison for efficient and sustainable biocatalysis

Biocatalysis is an established chemical synthesis technology that has by no means been restricted to research laboratories. The use of enzymes for organic synthesis has evolved greatly from early development to proof-of-concept - from small batch production to industrial scale. Different enzyme immobilization strategies contributed to this success story. Recently, the use of hydrogel materials for the immobilization of enzymes has been attracting great interest. Within this review, we pay special attention to recent developments in this key emerging field of research. Firstly, we will briefly introduce the concepts of both biocatalysis and hydrogel worlds. Then, we list recent interesting publications that link both concepts. Finally, we provide an outlook and comment on future perspectives of further exploration of enzyme immobilization strategies in hydrogels.

Multistage-Responsive Nanocomplexes Attenuate Ulcerative Colitis by Improving the Accumulation and Distribution of Oral Nucleic Acid Drugs in the Colon

Oral gene therapy has emerged as a potential optimal treatment for ulcerative colitis (UC). Nucleic acid drugs possessing versatility can not only inhibit inflammation but realize colon mucosal healing, fulfilling the clinical objective of UC therapy. However, the effective accumulation and distribution of oral nucleic acid drugs in the colon remain a considerable challenge. Furthermore, current delivery systems pay more attention to the accumulation of nucleic acid drugs in the colon, while the distribution of nucleic acid drugs in the colon, which plays a key role in the UC treatment, never catches the attention of researchers. Here, we used miR-320 as a model nucleic acid drug to develop a kind of multistage-responsive nanocomplexes (MSNs) based on polymeric nanocapsules and alginate. MSNs possess the pH responsiveness in the stomach, the enzyme responsiveness in the colonic lumen, and the redox responsiveness in the cytoplasm. In vivo imaging results showed that MSNs reach the colon within 2 h and effectively release miR-320 nanocapsules in the colonic lumen. The nanocapsules can further deliver miR-320 to the submucosal layer and even the muscular layer. Moreover, MSNs decreased the activity of myeloperoxidase and proinflammatory cytokines and exhibited anti-inflammatory activity by inhibiting the phosphorylation of IκBα and AKT, reducing colonic inflammation and enhancing mucosal repair. Therefore, MSNs can successfully alleviate UC by improving the accumulation and distribution of oral nucleic acid drugs in the colon, promoting the clinical translational application of nucleic acid drugs in the treatment of UC.

Preparation and characterization of colon-targeted pH/Time-dependent nanoparticles using anionic and cationic polymethacrylate polymers

Inflammatory bowel disease (IBD), which is a chronic inflammatory disease of the gastrointestinal system, has two subtypes: Ulcerative Colitis (UC) and Crohn's Disease (CD). Only pH-sensitive drug delivery systems are commonly utilized for the treatment of IBD, but their effectiveness is frequently obstructed by the change in intestinal pH. To overcome the inadequacy of only pH-dependent delivery systems, we developed in vitro evaluated both pH- and time-dependent nanoparticles loaded budesonide (BUD) for the treatment of IBD in this study. Anionic polymethacrylate was utilized as a pH-dependent polymer whereas cationic polymethacrylate was utilized as a time-dependent sustained release polymer. Nanoparticles were prepared through a single oil-in-water emulsion/solvent evaporation method. The encapsulation efficiency, mean particle size, zeta potential, polydispersity index (PDI), drug release profiles, drug release kinetics, and stability of these nanoparticles were investigated. In all formulations, mean particle sizes were below 250 nm and PDI values were between 0.1 and 0.3. Nanoparticles containing 90% anionic-10% cationic polymethacrylate polymers inhibited burst BUD release under acidic conditions and exhibited sustained drug release at neutral pH. Consequently, in the medication of IBD, BUD-loaded pH and time-dependent nanoparticles may be a promising choice as a drug delivery system.

SHARP hydrogel for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a relapsing and remitting inflammatory disease affecting millions of people worldwide. The active phase of IBD is characterized by excessive formation of reactive oxygen species (ROS) in the intestinal mucosa, which further accelerates the inflammatory process. A feasible strategy for the IBD treatment is thus breaking the oxidation-inflammation vicious circle by scavenging excessive ROS with the use of a suitable antioxidant. Herein, we have developed a novel hydrogel system for oral administration utilizing sterically hindered amine-based redox polymer (SHARP) incorporating covalently bound antioxidant SHA groups. SHARP was prepared via free-radical polymerization by covalent crosslinking of 2-hydroxyethyl methacrylate (HEMA), poly(ethylene oxide) methyl ether methacrylate (PEGMA) and a SHA-based monomer, N-(2,2,6,6-tetramethyl-piperidin-4-yl)-methacrylamide. The SHARP hydrogel was resistant to hydrolysis and swelled considerably (∼90% water content) under the simulated gastrointestinal tract (GIT) conditions, and exhibited concentration-dependent antioxidant properties in vitro against different ROS. Further, the SHARP hydrogel was found to be non-genotoxic, non-cytotoxic, non-irritating, and non-absorbable from the gastrointestinal tract. Most importantly, SHARP hydrogel exhibited a statistically significant, dose-dependent therapeutic effect in the mice model of dextran sodium sulfate (DSS)-induced acute colitis. Altogether, the obtained results suggest that the SHARP hydrogel strategy holds a great promise with respect to IBD treatment.

Anti-Inflammatory Effects of Curcumin in the Inflammatory Diseases: Status, Limitations and Countermeasures

Curcumin is a natural compound with great potential for disease treatment. A large number of studies have proved that curcumin has a variety of biological activities, among which anti-inflammatory effect is a significant feature of it. Inflammation is a complex and pervasive physiological and pathological process. The physiological and pathological mechanisms of inflammatory bowel disease, psoriasis, atherosclerosis, COVID-19 and other research focus diseases are not clear yet, and they are considered to be related to inflammation. The anti-inflammatory effect of curcumin can effectively improve the symptoms of these diseases and is expected to be a candidate drug for the treatment of related diseases. This paper mainly reviews the anti-inflammatory effect of curcumin, the inflammatory pathological mechanism of related diseases, the regulatory effect of curcumin on these, and the latest research results on the improvement of curcumin pharmacokinetics. It is beneficial to the further study of curcumin and provides new ideas and insights for the development of curcumin anti-inflammatory preparations.

Structural changes in pH-responsive gelatin/hydroxypropyl methylcellulose phthalate blends aimed at drug-release systems

The present study aimed to investigate the thermal- and pH-dependent gelation behavior of gelatin/HPMCP blends using ultraviolet (UV) spectrophotometry, viscoelasticity, and dynamic light scattering (DLS). We found that the release of lisinopril from gelatin/HPMCP gels can be inhibited at low pH. UV spectrophotometric analysis showed that pH had a significant effect on the transparency of aqueous HPMCP systems and gelatin/HPMCP gels. The viscoelastic patterns of gelatin/HPMCP at pH 4.6 considerably differed from those of gelatin/HPMCP at pH 5.2 and 6.0. DLS measurements showed that HPMCP molecules in low concentrations underwent strong aggregation below pH 4.8. Such HPMCP aggregation induces a physical barrier in the matrix structures of the gelatin/HPMCP gels, which inhibits the drug release at pH 1.2. This hydrogel delivery system using polymer blends of gelatin/HPMCP can be used in oral gel formulations with pH-responsive properties.

The Characterization of Scaffolds Based on Dialdehyde Chitosan/Hyaluronic Acid

In this work, two-component dialdehyde chitosan/hyaluronic acid scaffolds were developed and characterized. Dialdehyde chitosan was obtained by one-step synthesis with chitosan and sodium periodate. Three-dimensional scaffolds were prepared by the lyophilization method. Fourier transform infrared spectroscopy (FTIR) was used to observe the chemical structure of scaffolds and scanning electron microscopy (SEM) imaging was done to assess the microstructure of resultant materials. Thermal analysis, mechanical properties measurements, density, porosity and water content measurements were used to characterize physicochemical properties of dialdehyde chitosan/hyaluronic acid 3D materials. Additionally, human epidermal keratinocytes (NHEK), dermal fibroblasts (NHDF) and human melanoma cells (A375 and G-361) were used to evaluate cell viability in the presence of subjected scaffolds. It was found that scaffolds were characterized by a porous structure with interconnected pores. The scaffold composition has an influence on physicochemical properties, such as mechanical strength, thermal resistance, porosity and water content. There were no significant differences between cell viability proliferation of all scaffolds, and this observation was visible for all subjected cell lines.

Oral Core-Shell Nanoparticles Embedded in Hydrogel Microspheres for the Efficient Site-Specific Delivery of Magnolol and Enhanced Antiulcerative Colitis Therapy

Although magnolol (Mag), an anti-inflammatory natural compound, has been demonstrated to play protective effects on ulcerative colitis (UC), its application as an alternative therapeutic reagent for UC treatment is still greatly impeded due to its poor stability in the gastrointestinal tract and insufficient accumulation in the inflamed colon lesion. Nano-/microsized drug delivery systems can potentially overcome some challenges regarding the oral administration of phytochemicals, which still confront premature early drug release, degradation of NPs, or the sustained drug release of MPs. In this study, we primarily loaded Mag into the core-shell zein-based nanoparticles with chondroitin sulfate coating (Mag@CS-Zein NPs) with an average size of 142.27 ± 5.11 nm, showing significant macrophage-targeting and enhanced colon epithelial cellular uptake capacity. Then, we embedded Mag@CS-Zein NPs into hydrogel microspheres via an electrospraying technology. The Mag@CS-Zein NPsinMPs presented a uniform-sized sphere with an average size of 164.36 ± 6.29 μm and sustained drug-release profiles. Compared to CS-Zein NPs, the developed CS-Zein NPsinMPs exhibited prolonged colon retention on the inflammatory surface, as seen from ex vivo and in vivo imaging fluorescence adhesion experiments. Based on the advantage of the combination of hybrid nanoparticles-in-microparticles, oral administration of Mag@CS-Zein NPsinMPs significantly alleviated colitis symptoms in DSS-treated mice by regulating the expression levels of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) and anti-inflammatory cytokines (IL-10) and factor accelerated colonic mucosal barrier repair via upregulating the expression of ZO-1 and occludin. This study provides great insights into the oral drug delivery of natural compounds for UC therapy.

Sponge particulates for biomedical applications: Biofunctionalization, multi-drug shielding, and theranostic applications

Sponge particulates have attracted enormous attention in biomedical applications for superior properties, including large porosity, elastic deformation, capillary action, and three-dimensional (3D) reaction environment. Especially, the tiny porous structures make sponge particulates a promising platform for drug delivery, tissue engineering, anti-infection, and wound healing by providing abundant reservoirs of broad surface and internal network for cargo shielding and shuttling. To control the sponge-like morphology and improve the diversity of drug loading, some optimized preparation techniques of sponge particulates have been developed, contributing to the simplified preparation process and improved production reproducibility. Bio-functionalized strategies, including target modification, cell membrane camouflage, and hydrogel of sponge particulates have been applied to modulate the properties, improve the performance, and extend the applications. In this review, we highlight the unique physical properties and functions, current manufacturing techniques, and an overview of spongy particulates in biomedical applications, especially in inhibition of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectivity. Moreover, the current challenges and prospects of sponge particulates are discussed rationally, providing an insight into developing vibrant fields of sponge particulates-based biomedicine.