Polyaspartic Acid-Stabilized CaCO3-Containing In Situ Hydrogel for Protection and Treatment of Gastric Ulcer

pH-responsive bioadhesive with robust and stable wet adhesion for gastric ulcer healing

Development of bioadhesives that can be facilely delivered by endoscope and exhibit instant and robust adhesion with gastric tissues to promote gastric ulcer healing remains challenging. In this study, an advanced bioadhesive is prepared through free radical polymerization of ionized N-acryloyl phenylalanine (iAPA) and N-[tris (hydroxymethyl) methyl] acrylamide (THMA). The precursory polymer solution exhibits low viscosity with the capability for endoscope delivery, and the hydrophilic-hydrophobic transition of iAPA upon exposure to gastric acid can trigger gelation through phenyl groups assisted multiple hydrogen bonds formation and repel water molecules on tissue surface to establish favorable environment for interfacial interactions between THMA and functional groups on tissues. The in-situ formed hydrogel features excellent stability in acid environment (14 days) and exhibits firm wet adhesion to gastric tissue (33.4 kPa), which can efficiently protect the wound from the stimulation of gastric acid and pepsin. In vivo studies reveal that the bioadhesive can accelerate the healing of ulcers by inhibiting inflammation and promoting capillary formation in the acetic acid-induced gastric ulcer model in rats. Our work may provide an effective solution for the treatment of gastric ulcers clinically.

Preparation of antibacterial hydrogel from poly(aspartic hydrazide) and quaternized N-[3-(dimethylamino) propyl] methylacrylamide copolymer with antioxidant and hemostatic effects for wound repairing

Hydrogels as wound dressing have attracted extensive attention in past decade because they can provide moist microenvironment to promote wound healing. Herein, this research designed a multifunctional hydrogel with antibacterial property and antioxidant activity fabricated from quaternary ammonium bearing light emitting quaternized TPE-P(DAA-co-DMAPMA) (QTPDD) and poly(aspartic hydrazide) (PAH). The protocatechuic aldehyde (PCA) grafted to the hydrogel through dynamic bond endowed the hydrogel with antioxidant activity and the tranexamic acid (TXA) was loaded to enhance the hemostatic performance. The hydrogel possesses preferable gelation time for injectable application, good antioxidant property and tissue adhesion, improved hemostatic performance fit for wound repairing. Furthermore, the hydrogel has excellent antimicrobial property to both E. coli and S. aureus based on quaternary ammonium structure. The hydrogel also showed good biocompatibility and the in vivo experiments proved this hydrogel can promote the wound repairing rate. This study suggests that TXA/hydrogel with quaternary ammonium structure and dynamic grafted PCA have great potential in wound healing applications.

Gastric acid-responsive deformable sodium alginate/Bletilla striata polysaccharide in situ gel for the protection and treatment of alcohol-induced peptic ulcers

First-line drugs for peptic ulcer (PU) treatment are typically limited by poor targeting and adverse effects associated with long-term use. Despite recent advancements in novel therapeutic approaches for PU, the development of sustained-release delivery systems tailored to specific pathological characteristics remains challenging. Persistent inflammation, particularly gastric inflammatory microenvironment imbalance, characterizes the PU. In this study, we prepared an in situ gel composed of sodium alginate, deacetylated gellan gum, calcium citrate, and Bletilla striata polysaccharide (BSP) to achieve sustained release of BSP. The BSP in situ gel demonstrated favorable fluidity in vitro and completed self-assembly in vivo in response to the acidic milieu at a pH of 1.5. Furthermore, the shear, extrusion, and deformation properties increased by 26.4 %, 103.7 %, and 46.3 %, respectively, with long-term gastric retention (4 h) and mucosal adaptation. Animal experiments confirmed that the BSP in situ gel could attenuate necrotic injury and inflammatory cell infiltration, maintain mucosal barrier integrity, regulate cytokine imbalance and inflammation-associated hyperapoptosis, thus effectively alleviate the inflammatory microenvironmental imbalance in PU without significant side effects. Overall, our findings demonstrated that the BSP in situ gel is a promising therapeutic strategy for PU and opens avenues for developing self-assembled formulations targeting the pathological features of PUs.

Multifunctional gallic acid self-assembled hydrogel for alleviation of ethanol-induced acute gastric injury

Ethanol-induced acute gastric injury is a prevalent type of digestive tract ulcer, yet conventional treatments strategies frequently encounter several limitations, such as poor bioavailability, degradation of enzymes and adverse side effects. Gallic acid (GA), a natural compound extracted from dogwood, has demonstrated potential protective effects in mitigating acute gastric injury. However, its poor stability and limited bioavailability have restricted applications in vivo. To address these issues, we report a hydrogel constructed only by gallic acid with high bioavailability for alleviation of gastric injury. Molecular dynamic simulation studies revealed that the self-assembly of GA into hydrogel was predominantly attributed to π-π and hydrogen bonds. After assembling, the GA hydrogel exhibits superior anti-oxidative stress, anti-apoptosis and anti-inflammatory properties compared with free GA. As anticipated, in vitro experiments demonstrated that GA hydrogel possessed the remarkable ability to promote the proliferation of GES-1 cells, and alleviates apoptosis and inflammation caused by ethanol. Subsequent in vivo investigation further confirmed that GA hydrogel significantly alleviated ethanol-triggered acute gastric injury. Mechanistically, GA hydrogel treatment enhanced the antioxidant capacity, reduced oxidative stress while simultaneously suppressing the secretion of pro-inflammatory cytokines and reduced the production of pro-apoptotic proteins during the process of gastric injury. Our finding suggest that this multifunctional GA hydrogel is a promising candidate for gastric injury, particularly in cases of ethanol-induced acute gastric injury.