Sustained release of an antitumoral drug from alginate-chitosan hydrogel beads and its potential use as colonic drug delivery

A novel injectable sodium alginate/chitosan/sulfated bacterial cellulose hydrogel as biohybrid artificial pancreas for real-time glycaemic regulation

Type 1 diabetes mellitus (T1DM) are characterized by blood glucose elevation with pancreatic β cells deficiency. As a safe alternative to frequent subcutaneous insulin injection, pancreatic β cell transplantation provides a promising therapeutic option for blood glucose control in T1DM. However, pancreatic β cell transplantation faces intractable challenges of the poor viability and severe host immune rejection. Therefore, a novel approach capable of improving the poor oxygen/nutrients supply and severe host immune rejection is highly desired. Herein, a novel biohybrid artificial pancreas, presenting glucose-dependent insulin release behavior, is constructed via pancreatic β cells encapsulating in a hydrogel scaffold. The hydrogel scaffold is made of the commixture of sodium alginate (SA), chitosan (CS) and sulfated bacterial cellulose (SBC). The biocompatible three-dimensional (3D) hydrogels protected pancreatic β cells from immune response but also allowed the exchange of nutrients and insulin. As a result of the synergistic effect, the biohybrid artificial pancreas can reverse the hyperglycemia and achieve sustained glycemic control for at least 30 days in diabetic mice. Collectively, we consider that this biohybrid artificial pancreas with an elaborate structure could provide an effective option for the treatment of type 1 diabetes.

A novel hydrogel containing 4-methylcatechol for skin regeneration: in vitro and in vivo study

Skin damages are usual physical injuries and different studies have been done to improve wound healing. Hydrogel due to its properties like a moist environment and cooling wound site is a good option for wound treatment. In this study, we evaluated the consequence of using alginate/chitosan hydrogel contained various dosages of 4-Methylcatechol (0, 0.1, 1% (W/W)) on wound healing. After hydrogel fabrication, different tests like SEM, swelling, release, weight loss, and hemo- and cytocompatibility were done to characterize fabricated hydrogels. Finally, the rat model was used to assess Alginate/Chitosan hydrogel's therapeutic function containing 0.1 and 1% of 4-Methylcatechol. The pore size of hydrogel was between 24.5 ± 9 and 62.1 ± 11.63 µm and about 90% of hydrogel was lost after 14 days in the weight loss test. Blood compatibility and MTT assay showed that hydrogels were nontoxic and improved cell proliferation. In vivo test showed that Alginate/Chitosan/0.1%4-Methylcatechol improved wound healing and the results were significantly better than the gauze-treated wound. Our results showed dose depending effect of 4-Methylcatechol on wound healing. This study shows the treatment effect of 4-Methylcatechol on wound healing and the possibility of using it for treating skin injuries.

Magnetic Microsphere Scaffold-Based Soft Microbots for Targeted Mesenchymal Stem Cell Delivery

A soft microbot assembled from individual magnetic microsphere scaffold (MMS) beads carrying mesenchymal stem cells (MSC) is navigated under magnetic actuation, where an oscillating field induces mechanical flexion to propel the microbot toward the target site. A seven-bead microbot attained a top translational speed of 205.6 µm s-1 (0.068 body length s-1 ) under 10 mT and 2 Hz field oscillation. The shallow flexion angle (10-24.5°) allows precision movements required to navigate narrow spaces. Upon arrival at the target site, the MMS beads unload their MSC cargo following exposure to a phosphate-buffered saline (PBS) solution, mimicking the extracellular fluid's sodium concentration. The released stem cells have excellent viability and vitality, promoting rapid healing (i.e., 83.2% vs 49%) in a scratch-wound assay. When paired with minimally invasive surgical methods, such as laparoscopy and endoscopic surgery, the microbot can provide precise stem cell delivery to hard-to-reach injury sites in the body to promote healing. Moreover, the microbot is designed to be highly versatile, with individual MMS beads customizable for cargoes of live cells, biomolecules, bionanomaterials, and pharmaceutical compounds for various therapeutic requirements.

Role of Berberine Thermosensitive Hydrogel in Periodontitis via PI3K/AKT Pathway In Vitro

Periodontitis is a long-term inflammatory illness and a leading contributor to tooth loss in humans. Due to the influence of the anatomic parameters of teeth, such as root bifurcation lesions and the depth of the periodontal pocket, basic periodontal treatment on its own often does not completely obliterate flora microorganisms. As a consequence, topical medication has become a significant supplement in the treatment of chronic periodontitis. Berberine (BBR) has various pharmacological effects, such as hypoglycemic, antitumor, antiarrhythmic, anti-inflammatory, etc. The target of our project is to develop a safe and non-toxic carrier that can effectively release berberine, which can significantly reduce periodontal tissue inflammation, and to investigate whether berberine thermosensitive hydrogel can exert anti-inflammatory and osteogenic effects by modulating phosphatifylinositol-3-kinase/Protein Kinase B (PI3K/AKT) signaling pathway. Consequently, firstly berberine temperature-sensitive hydrogel was prepared, and its characterizations showed that the mixed solution gelated within 3 min under 37 °C with a hole diameter of 10-130 µm, and the accumulation of berberine release amounted to 89.99% at 21 days. CCK-8 and live-dead cell staining results indicated that this hydrogel was not biotoxic, and it is also presumed that the optimum concentration of berberine is 5 µM, which was selected for subsequent experiments. Real-time polymerase chain reaction (qRT-PCR) and Western blotting (WB)results demonstrated that inflammatory factors, as well as protein levels, were significantly reduced in the berberine-loaded hydrogel group, and LY294002 (PI3K inhibitor) could enhance this effect (p < 0.05). In the berberine-loaded hydrogel group, osteogenesis-related factor levels and protein profiles were visibly increased, along with an increase in alkaline phosphatase expression, which was inhibited by LY294002 (p < 0.05). Therefore, berberine thermosensitive hydrogel may be an effective treatment for periodontitis, and it may exert anti-inflammatory and osteogenic effects through the PI3K/AKT signaling pathway.

Magnetic-responsive hydrogels: From strategic design to biomedical applications

Smart hydrogels which can respond to external stimuli have been widely focused with increasing interest. Thereinto, magnetic-responsive hydrogels that are prepared by embedding magnetic nanomaterials into hydrogel networks are more advantageous in biomedical applications due to their rapid magnetic response, precisely temporal and spatial control and non-invasively remote actuation. Upon the application of an external magnetic field, magnetic hydrogels can be actuated to perform multiple response modes such as locomotion, deformation and thermogenesis for therapeutic purposes without the limit of tissue penetration depth. This review summarizes the latest advances of magnetic-responsive hydrogels with focus on biomedical applications. The synthetic methods of magnetic hydrogels are firstly introduced. Then, the roles of different response modes of magnetic hydrogels played in different biomedical applications are emphatically discussed in detail. In the end, the current limitations and future perspectives for magnetic hydrogels are given.

Improving sciatic nerve regeneration by using alginate/chitosan hydrogel containing berberine

Peripheral nerve injuries are the common results of trauma that lead to pain and handicap in patients. Berberine due to its properties like antibiotic, immunostimulant, antitumor, antimotility, and positive effect on neurological disorders can be used to enhance peripheral nerve injuries. In this study, alginate/chitosan hydrogel containing different concentrations of berberine (0, 0.1, 1, 10% (w/v)) was created, evaluated, and applied as a scaffold for sciatic nerve regeneration. To prepare hydrogel, sodium alginate was dissolved in distilled water and cross-linked with CaCl2, and chitosan was dissolved in acetic acid and cross-linked with β-glycerol phosphate. The structure, release, swelling, weight loss, cytocompatibility, and hemocompatibility of the prepared hydrogels were assessed. The sciatic nerve crush was created in rats and fabricated hydrogels were injected, and functional analysis was used to evaluate their effectiveness. The results of physical characterization of the hydrogel indicated that the initial average pore size was about 39 μm and about 70% of the main weight of hydrogels was lost after incubation for 21 days and hemocompatibility of hydrogels was also confirmed. The MTT assay showed the cytocompatiblity of hydrogels and also indicated that berberine has dose-dependence effect on cell proliferation. The in vivo results showed the positive effect of berberine especially the hydrogel contained 1% of berberine on regeneration of sciatic nerve. Based on this study, Alg/Chit hydrogel can be applied as a treatment to heal peripheral nerve injuries. Graphical abstract.

Stability of tuna trypsin-loaded alginate-chitosan beads in acidic stomach fluid and the release of active enzyme in a simulated intestinal tract environment

Encapsulation properties of trypsin from tonggol tuna (Thunnus tonggol) spleen using different materials including alginate (AG), low and high molecular weight chitosan (LC and HC, respectively), and soy lecithin (SL) were studied. The highest encapsulation efficiency and greatest relative activity were found in AG/LC beads after simulated gastric phase (p < .05). AG/LC encapsulated trypsin was used in simulated in vitro gastrointestinal tract for hydrolysis of sodium caseinate, soy protein isolate and fish mince, in which all protein samples were hydrolyzed as indicated by the increased α-amino group content (p < .05). Higher degradation was attained when beads containing trypsin were added. When AG/LC beads packed in blister pack were stored for 8 weeks at refrigerated temperature, a 26% decrease in activity occurred. Therefore, encapsulated tonggol tuna spleen trypsin can be prepared using AG/LC to withstand structural breakdown in stomach, but be released as an active protease within intestinal tract. PRACTICAL APPLICATION: Spleen from tonggol tuna is a by-product, which can be used as a source of trypsin, a proteolytic enzyme. The trypsin that was encapsulated within alginate and low molecular weight chitosan beads was released in the intestinal phase and was retained proteolytic activity. Therefore, this encapsulated trypsin can be packaged in capsules and taken as a supplement to aid protein digestion in the gastrointestinal tract, especially for people that need such digestive aids.

The influence of natural deep eutectic solvents on bioactive natural products: studying interactions between a hydrogel model and Schisandra chinensis metabolites

Natural Deep Eutectic Solvent (NADES) species can exhibit unexpected solubilizing power for lipophilic molecules despite their simple composition: hydrophilic organic molecules and water. In the present study, the unique properties of NADES species were applied in combination with a model polymer system: a hydrophilic chitosan/alginate hydrogel. Briefly, NADES species (e.g., mannose-dimethylurea-water, 2:5:5, mole/mole) formed matrices to 1) dissolve lipophilic molecules (e.g., curcumin), 2) load lipophilic molecule(s) into the hydrogel, and 3) spontaneously vacate from the system. NADES species ubiquitously occur in natural sources, and a crude extract is a mixture of the NADES species and bioactive metabolites. Based on these ideas, we hypothesized that the crude extract may also allow the loading of natural bioactive molecules from a natural NADES species into (bio)hydrogel systems. To evaluate this hypothesis in vitro, Schisandra chinensis fruit extract was chosen as a representative mixture of lipophilic botanical molecules and hydrophilic NADES species. The results showed that the NADES matrix of S. chinensis was capable of loading at least three bioactive lignans (i.e., gomisin A, gomisin J, and angeloylgomisin H) into the polymer system. The lipophilic metabolites can subsequently be released from the hydrogel. The outcomes suggest that a unique drug delivery mechanism may exist in nature, thereby potentially improving the bioavailability of lipophilic metabolites through physicochemical interactions with the NADES.

Alginate-Based Composite Sponges as Gastroretentive Carriers for Curcumin-Loaded Self-Microemulsifying Drug Delivery Systems

Alginate-based composite sponges were developed as carriers to prolong the gastric retention time and controlled release of curcumin-loaded self-microemulsifying drug delivery systems (Cur-SMEDDS). Liquid Cur-SMEDDS was incorporated into a solution made up of a mixture of polymers and converted into a solid form by freeze-drying. The ratio of alginate as the main polymer, adsorbent (colloidal silicon dioxide), and additional polymers—sodium carboxymethyl cellulose (SCMC), hydroxypropyl methylcellulose (HPMC)—was varied systematically to adjust the drug loading and entrapment efficiency, sponge buoyancy, and the release profile of Cur-SMEDDS. The optimum composite sponge was fabricated from a 4% alginate and 2% HPMC mixed solution. It immediately floated on simulated gastric fluid (SGF, pH 1.2) and remained buoyant over an 8 h period. The formulation exhibited an emulsion droplet size of approximately 30 nm and provided sustained release of Cur-SMEDDS in SGF, reaching 71% within 8 h compared with only 10% release from curcumin powder. This study demonstrates the potential of alginate-based composite sponges combined with self-microemulsifying formulations for gastroretention applications involving poorly soluble compounds.

Mucoadhesive microparticles for gastroretentive delivery: preparation, biodistribution and targeting evaluation

The aim of this research was to prepare and characterize alginate-chitosan mucoadhesive microparticles containing puerarin. The microparticles were prepared by an emulsification-internal gelatin method using a combination of chitosan and Ca²⁺ as cationic components and alginate as anions. Surface morphology, particle size, drug loading, encapsulation efficiency and swelling ratio, in vitro drug released, in vitro evaluation of mucoadhesiveness and Fluorescence imaging of the gastrointestinal tract were determined. After optimization of the formulation, the encapsulation efficiency was dramatically increased from 70.3% to 99.2%, and a highly swelling ratio was achieved with a change in particle size from 50.3 ± 11.2 μm to 124.7 ± 25.6 μm. In ethanol induced gastric ulcers, administration of puerarin mucoadhesive microparticles at doses of 150 mg/kg, 300 mg/kg, 450 mg/kg and 600 mg/kg body weight prior to ethanol ingestion significantly protected the stomach ulceration. Consequently, significant changes were observed in inflammatory cytokines, such as prostaglandin E₂ (PGE₂), tumor necrosis factor (TNF-α), interleukin 6 (IL-6), and interleukin1β (IL-1β), in stomach tissues compared with the ethanol control group. In conclusion, core-shell type pH-sensitive mucoadhesive microparticles loaded with puerarin could enhance puerarin bioavailability and have the potential to alleviate ethanol-mediated gastric ulcers.