Ultra-stable hydrogel boosts gastrointestinal wound repair

Researchers at The Hong Kong Polytechnic University (PolyU) have announced a new acid-resistant material that could transform the treatment of gastrointestinal wounds and disease. The innovation, known as an ‘ultra-stable mucus-inspired hydrogel’ (UMIH), is designed to withstand the highly acidic environment of the stomach, overcoming a long-standing limitation of conventional hydrogels.

Hydrogels are gelatine-like materials capable of absorbing and retaining large amounts of water. They are widely used in medicine to promote wound healing and enable sustained drug release. However, most existing hydrogels degrade rapidly in acidic conditions, severely restricting their use in gastrointestinal applications.

Inspired by the protective properties of natural gastric mucus, the PolyU research team developed the UMIH hydrogel to adhere up to 15 times more strongly than conventional gastric mucosal protectants. The material shows significant promise for gastrointestinal wound repair and targeted drug delivery. The hope is that the hydrogel could be developed for large-scale commercialisation.

The research was conducted in collaboration with researchers and clinicians from Sichuan University. In animal studies, UMIH significantly improved gastrointestinal wound healing and outperformed a clinically approved mucosal protectant commonly used to protect the stomach lining.

Potential clinical impact

Study leader, Professor Wang Zuankai, associate vice president of research at PolyU, highlighted the broad medical potential of the new material.

“UMIH shows promise in treating gastroesophageal reflux and gastric ulcers, and in protecting post-surgical wounds. It can also be combined with endoscopic drug delivery for minimally invasive therapy,” said Zuankai. “This research establishes UMIH as a transformative, extremely acid-tolerant platform, with immediate applications in gastrointestinal repair and targeted drug delivery, while also opening avenues for next-generation implantable devices to accelerate translation to the clinic.”

Outperforming existing treatments

Aluminium phosphate gel (APG) is a widely used, clinically approved mucosal protectant and antacid for treating gastric ulcers and gastro-oesophageal reflux. According to Professor Wang, experimental data under simulated gastric conditions (pH 2) showed that UMIH achieved a wet adhesion strength of 64.7 kilopascals – 15 times higher than APG.

While APG fully degraded after three days, UMIH retained around 50 percent of its structural integrity after seven days. Laboratory tests on cultured gastrointestinal cells showed no signs of toxicity. In addition, UMIH inhibited the growth of Escherichia coli and Staphylococcus aureus, suggesting it may hold some antibacterial potential.

A mucus-inspired molecular design

Like traditional hydrogels, UMIH is formed from a polymer mesh that absorbs water, creating a soft yet robust structure. Its exceptional acid resistance comes from the integration of three molecular components: ELR-IK24, which binds hydrogen ions to reduce local acidity; tannic acid, which enhances adhesion; and HDI, which stabilises the hydrogel structure in acidic environments.

“Our hydrogel is a synergistic combination of three essential molecular components. This multi-crosslinking architecture keeps UMIH firmly intact in strong acid while maintaining softness and injectability – qualities well suited to clinical use,” said Yeung Yeung Chau, research associate in PolyU’s Department of Mechanical Engineering.

Promising animal studies and future directions

Animal testing further demonstrated the hydrogel’s effectiveness. “We tested UMIH in pig and rat models of oesophageal injury. Compared with control animals and APG-treated animals, UMIH adhered more firmly to wound faces and improved healing. UMIH reduced tissue damage and inflammation and promoted the growth of new blood vessels, which is essential for healing,” explained Dr Xiao Yang, a postdoctoral fellow at PolyU.

Although clinical trials will be required to confirm safety and effectiveness in humans, UMIH is highly promising due to its low-cost, mass-producibility and composition with established safety profiles. The research team now plans to combine UMIH with drug-release systems and implantable flexible electronics, moving it closer to smart gastrointestinal devices capable of real-time treatment and monitoring.