Customized Hydrogel for Sustained Release of Highly Water-Soluble Drugs

Dual network construction strategy of starch and calcium alginate to prepare tapioca pearls with efficiently embedded gamma-aminobutyric acid

The supplementation of gamma aminobutyric acid (GABA) through food matrices such as tapioca pearls has gained consumer acceptance due to better palatability and digestive release. However, GABA can leak from the pearls during the cooking process. This study proposes a simple and cost-effective one-pot method where sodium alginate and calcium lactate are directly added to the tapioca starch matrix to form dual networks, reducing the cooking leakage rate from 36.27 % to 15.52 %. Furthermore, this method extends the sustained release time of GABA in the digestive tract. The microstructural analysis indicates that during the cooking process, sodium alginate and calcium lactate interact to form a calcium alginate gel network, which effectively fills the voids within the starch gel matrix, thereby reducing the leakage of small GABA molecules. This study also examined the effects of calcium alginate networks on starch matrix and the interactions between these two networks. The starch‑calcium alginate dual network reduced GABA leakage during the cooking process in tapioca pearls, while improving its sustained release during digestion. The present work provides a new approach to improving encapsulation and digestive release of small molecules and water-soluble nutrients.

Advancements and Prospects of pH-Responsive Hydrogels in Biomedicine

As an intelligent polymer material, pH-sensitive hydrogels exhibit the capability to dynamically sense alterations in ambient pH levels and subsequently initiate corresponding physical or chemical responses, including swelling, contraction, degradation, or ion exchange. Given the significant pH variations inherent in human pathophysiological microenvironments, particularly in tumor tissues, inflammatory lesions, and the gastrointestinal system, these smart materials demonstrate remarkable application potential across diverse domains such as targeted drug delivery systems, regenerative medicine engineering, biosensing, and disease diagnostics. Recent breakthroughs in nanotechnology and precision medicine have substantially propelled advancements in the design and application of pH-responsive hydrogels. This review systematically elaborates on the current research progress and future challenges regarding pH-responsive hydrogels in biomedical applications, with particular emphasis on their stimulus-response mechanisms, fabrication methodologies, multifunctional integration strategies, and application scenarios.

Diatom contained alginate-chitosan hydrogel beads with enhanced hydrogen bonds and ionic interactions for extended release of gibberellic acid

Hydrogels in agriculture offer controlled release, however, face issues with rapid disintegration, swift release, and inability to protect active ingredients. To overcome this, the study presents a hydrogel delivery system that uses dopamine-functionalized nanoporous diatom (DE-PDA) microparticles entrapped in alginate and chitosan matrices to deliver plant growth hormone, gibberellic acid (GA) that suffers from instability, limiting its field application. Developed GA@hydrogel beads exhibited an encapsulation efficiency of 85.2 % and demonstrated thermal and functional properties that suggested complex interactions between biopolymers. They showed enhanced stability, retention, and extended release for GA, improving tomato seed germination and plant growth. The GA release was governed by Fickian diffusion and the polymer relaxation with 86.3 % release by the 15th day, with a high swelling rate compared to a system without DE-PDA that only sustained GA release for 5 h. The GA@hydrogel system boosts tomato seed germination rates to 100 % on the third day for a 0.05 % GA@hydrogel formulation, demonstrating enhanced seedling growth. Also, they prove more effective than free GA in increasing the physiological parameters of tomato plants. Further, the pot experiments show enhanced plant growth, suggesting a new trend of GA delivery to plants through soil.

Research progress on the performance of expandable systems for long-term gastric retention

Gastroretentive systems have gained attention due to their prolonged retention time in the human body, and they have the potential to improve treatment effects, simplify treatment regimens, and improve patient compliance. Among these systems, expandable gastroretentive systems (EGRSs) have emerged as an important type of carrier that can reside in the stomach for a desired period through on-demand expansion for drug delivery, obesity intervention, and medical diagnosis. As the physiological environment significantly influences the performance of EGRSs, here, the physiological factors such as the stomach's physiological structure and activity pattern, and the character of gastric juice are summarized. Following this, the research progress of EGRSs from ingestion to removal for long-term gastric retention is discussed with respect to the influencing factors and reinforcement strategies in mechanics. Additionally, as the duration of gastric retention increases, safety concerns arise. As such, safety issues in terms of removal after retention or in an emergency are also analyzed. Finally, the biomedical application of EGRSs as diagnostic and therapeutic tools and the potential direction for further research are discussed. STATEMENT OF SIGNIFICANCE: Expandable gastroretentive systems (EGRSs) resist gastric emptying due to their size exceeding the pylorus diameter, offering promising advantages for obesity intervention, drug delivery, and carrying sensors. However, a long gastroretentive time only by such a size mismatch is hard to be achieved due to the uninterrupted stomach contraction and gastric juice erosion. Recent studies indicate that the retention time and stability of EGRSs can be regulated by adjusting their mechanical properties. Hence, this review summarizes the state-of-art progress of EGRSs for long-term gastric retention from a mechanical perspective for the first time, focuses on material components and synthesis methods, and the reinforcement strategies, and suggests the required mechanical property parameters of EGRSs.

Trends in Photopolymerization 3D Printing for Advanced Drug Delivery Applications

Since its invention in the 1980s, photopolymerization-based 3D printing has attracted significant attention for its capability to fabricate complex microstructures with high precision, by leveraging light patterning to initiate polymerization and cross-linking in liquid resin materials. Such precision makes it particularly suitable for biomedical applications, in particular, advanced and customized drug delivery systems. This review summarizes the latest advancements in photopolymerization 3D printing technology and the development of biocompatible and/or biodegradable materials that have been used or shown potential in the field of drug delivery. The drug loading methods and release characteristics of the 3D printing drug delivery systems are summarized. Importantly, recent trends in the drug delivery applications based on photopolymerization 3D printing, including oral formulations, microneedles, implantable devices, microrobots and recently emerging systems, are analyzed. In the end, the challenges and opportunities in photopolymerization 3D printing for customized drug delivery are discussed.

"Bamboo-like" strong and tough sodium alginate/polyacrylate hydrogel fiber with directional controlled release for wound healing promotion

Skin, as the biggest organ and outermost surface of the human body, is prone to injury due to various challenges, especially the expanding potential of accidents, which bring a huge social and economic burden. Hydrogels are emerging as the most promising candidate for wound dressings, which not only fulfill the varied requirements of dressings but also serve as drug carriers. But limited breathability, rapid drug release, and inadequate mechanical properties remains a significant challenge. Herein, we report a strong and tough sodium alginate/polyacrylate hydrogel fibers-based dressing with directional controlled drug release for wound healing promotion. Mimicking the bamboo structure, the drug solution is encapsulated within the fiber, and the rate of drug release can be modulated by controlling the wall thickness of the fiber. A cross-network structure in the hydrogel fiber through hydrogen bond and calcium ion crosslinking resulted in a 38 % increase in tensile strength. By precisely controlling the feeding process during weaving, drug-loaded fibers can be prepared at specific locations to facilitate targeted delivery to skin wound sites. Drug-loaded fabric has the breathability and biocompatibility required for dressings to promote wound healing. The findings highlight the potential of alginate/polyacrylate hydrogel fabrics for effective wound treatment.

Designing thermoreversible gels for extended release of mosquito repellent

Mosquito-borne diseases are responsible for 700 000 deaths annually. Current outdoor protective strategies primarily focus on direct skin application of commercial repellents (i.e., aerosol sprays or topical lotions) which are typically limited to efficacy times of ≤10 hours due to rapid evaporation and dermal absorption. Consequently, frequent reapplication for continuous protection can increase associated health hazards and cause noncompliance. This study utilizes Hansen solubility parameter modeling to design physical gels composed of insect-repelling N,N-diethyl-meta-toluamide (DEET) and modacrylic copolymer poly(acrylonitrile-co-vinyl chloride) (P(AN-VC)). The P(AN-VC)/DEET composites exhibit tunable and reversible sol-gel transition temperatures that can meet the thermomechanical stability demands of the intended application and permit facile transition to commercial melt processing techniques such as injection molding, filament spinning, or film casting. P(AN-VC)/DEET gel films demonstrate mosquito repellency for more than half a year-performing longer than any other known material to date-due to the high reservoir of repellent and its desorption hindrance from the polymer matrix. Therefore, P(AN-VC)/DEET gels hold significant potential for extended protection against mosquitos and other biting arthropods.

Multifunctional Hydrogel with 3D Printability, Fluorescence, Biodegradability, and Biocompatibility for Biomedical Microrobots

As micron-sized objects, mobile microrobots have shown significant potential for future biomedical applications, such as targeted drug delivery and minimally invasive surgery. However, to make these microrobots viable for clinical applications, several crucial aspects should be implemented, including customizability, motion-controllability, imageability, biodegradability, and biocompatibility. Developing materials to meet these requirements is of utmost importance. Here, a gelatin methacryloyl (GelMA) and (2-(4-vinylphenyl)ethene-1,1,2-triyl)tribenzene (TPEMA)-based multifunctional hydrogel with 3D printability, fluorescence imageability, biodegradability, and biocompatibility is demonstrated. By using 3D direct laser writing method, the hydrogel exhibits its versatility in the customization and fabrication of 3D microstructures. Spherical hydrogel microrobots were fabricated and decorated with magnetic nanoparticles on their surface to render them magnetically responsive, and have demonstrated excellent movement performance and motion controllability. The hydrogel microstructures also represented excellent drug loading/release capacity and degradability by using collagenase, along with stable fluorescence properties. Moreover, cytotoxicity assays showed that the hydrogel was non-toxic, as well as able to support cell attachment and growth, indicating excellent biocompatibility of the hydrogel. The developed multifunctional hydrogel exhibits great potential for biomedical microrobots that are integrated with customizability, 3D printability, motion controllability, drug delivery capacity, fluorescence imageability, degradability, and biocompatibility, thus being able to realize the real in vivo biomedical applications of microrobots.

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as an insulin carrier in silk fibroin hydrogels for transdermal delivery via iontophoresis

In this study, silk fibroin (SF) was utilized as the starting material to fabricate physically crosslinked hydrogels. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) was synthesized and characterized as a drug carrier, with insulin as the model drug. PEDOT:PSS, with a high electrical conductivity of 1666 ± 49 S cm-1, interacted with insulin molecules via electrostatic interaction by replacing the dopant PSS molecules. Insulin-loaded PEDOT:PSS embedded in the SF hydrogel resulted in an increase in the degree of swelling, pore size, and mesh size of the hydrogel. In the in vitro release and release-permeation experiments, the amounts of insulin release and release-permeation were investigated using a modified Franz diffusion cell, under the effects of SF concentrations, electric fields, and pH values. The amounts of insulin release and release-permeation from the pristine SF hydrogel and the PEDOT:PSS/SF hydrogel followed the power laws with the scaling exponents close to 0.5, indicating the Fickian diffusion or the concentration gradient. Under electric fields, with or without PEDOT:PSS used as the drug carrier, the insulin amount and diffusion coefficient were shown to increase with the increasing electric field due to the electro-repulsive forces between the cathode and insulin molecules and SF chains, electroosmosis, and SF matrix swelling. The SF hydrogel and PEDOT:PSS as the drug carrier are demonstrated herein as new components in the transdermal delivery system for the iontophoretically controlled insulin basal release applicable to diabetes patients.

Combining emulsion electrospinning with surface functionalization to fabricate multistructural PLA/CS@ZIF-8 nanofiber membranes toward pH-responsive dual drug delivery

Developing of the multifunctional polymeric carrier for controlled drug release is still one of most challenging task. In this work, a pH-responsive dual drug delivery system was designed and prepared based on the zeolitic imidazolate framework-8 (ZIF-8). The poly(lactic acid)/chitosan (PLA/CS) core-shell nanofiber membranes by emulsion electrospinning, which the hydrophilic drug (Astragalus Polysacharin, APS) was encapsulated in the CS core and the hydrophobic drug (Camptothecin, CPT) was loaded into the PLA shell, respectively. Subsequently, ZIF-8 nanoparticles served as the protective layer were immobilized on the surface of PLA/CS to form multi-structural PLA/CS@ZIF-8 nanofiber membranes. In vitro drug release of nanofiber membranes were studied in the acidic and neutral medium, respectively. The results were that the hydrophilicity and surface roughness of nanofiber membranes rose with increasing of 2-MIM concentrations. The nanofiber membranes also had excellent pH-responsive and controlled release property. Furthermore, the drug release of PLA/CS@ZIF-8 for either APS or CPT were all carried out in a coexisting manner of diffusion and skeleton corrosion. In addition, in vitro cytotoxicity assay indicated nanofiber membranes with good cytocompatibility. Therefore, the multi-structured PLA/CS@ZIF-8 nanofiber membranes has been used as a potential pH-responsive dual drug release system.

A Temperature/pH Double-Responsive and Physical Double-Crosslinked Hydrogel Based on PLA and Histidine

Hydrogel is a good drug carrier, widely used in the sustained-release aspect of tumor drugs, which can achieve the continuous release of drugs to the tumor sites. In this study, diethylene glycol monomethyl ether methacrylate (MEO2MA) and poly (ethylene glycol) methyl ether methacrylate (OEGMA) are temperature-sensitive monomers. N-Methacryloyl-L-Histidine (Mist) is pH sensitive monomer and ligand for metal coordination bond. The temperature-sensitive monomers and pH sensitive monomer with stereocomplex of modified polylactic acid (HEMA-PLLA30/PDLA30) were mixed, under 2,2'-azobis (2-methylpropionitrile) (AIBN) as radical initiator, polymer was formed by free-radical polymerization. The polymer was then immersed in ZnSO4 solution, the imidazole group of Mist monomer forms a tridentate metal coordination bond with Zn2+, temperature/pH double-responsive and physical double-crosslinked hydrogel was finally obtained. Comparing the hydrogen bond hydrogel, hydrogen bond and metal coordination bond double crosslinking hydrogel, metal coordination bond hydrogel, testing thermal stability, viscoelasticity, swelling, and morphology of three hydrogels. In addition, using UV-Visible spectroscopy (UV-Vis) to test the sustained release of the hydrophobic drug doxorubicin hydrochloride (DOX-HCl) in the human tumor environment (37 °C, pH = 5). We found that the temperature/pH double-responsive and physical double-crosslinked hydrogel had the most potential for the sustained drug release.