Oxygen-generating gel closes chronic wounds that conventional dressings cannot heal

Chronic wounds - injuries that fail to close within a month - affect an estimated 12 million people worldwide each year, with approximately 4.5 million cases in the United States alone. Roughly one in five patients eventually requires an amputation. As global rates of diabetes and aging populations both grow, those numbers are rising.

The standard toolkit for chronic wound management has expanded in recent decades - antimicrobial dressings, growth factor therapies, negative pressure devices - but none directly target what UC Riverside bioengineers believe is the fundamental biological obstacle: oxygen deficiency in the deepest layers of damaged tissue.

The oxygen deficit that stalls repair

Wound healing progresses through four stages: inflammation, vascularization, remodeling, and regeneration. Each requires oxygen. When tissue is damaged, blood supply is disrupted. In healthy patients, new blood vessels grow relatively quickly to restore oxygen delivery. In diabetic patients and the elderly, that vascularization process is impaired or delayed, leaving deep tissue in prolonged hypoxia.

Hypoxia derails healing in multiple ways. Oxygen-deprived cells cannot complete the metabolic processes needed to rebuild tissue. Anaerobic bacteria thrive in low-oxygen environments, raising infection risk. Macrophages - the immune cells responsible for clearing debris and coordinating repair - function poorly without adequate oxygen. The wound cycles through inflammation without progressing to active repair.

"Chronic wounds do not heal by themselves," said Iman Noshadi, UCR associate professor of bioengineering and the team lead. "In any of the four stages of healing, lack of a stable, consistent oxygen supply is a big problem."

How the electrochemical gel works

The approach, detailed in Nature Communications Materials, centers on a soft, flexible gel containing water and a choline-based liquid that is antibacterial, nontoxic, and biocompatible. Before setting, the gel conforms to the precise contours of a wound, filling crevices where oxygen levels tend to be lowest and infection risk is highest.

Once applied, the gel is paired with a small battery similar to those used in hearing aids. The battery drives a continuous electrochemical reaction: water molecules within the gel are split into hydrogen and oxygen. The oxygen diffuses slowly and steadily into surrounding tissue, maintaining delivery for up to 30 days. Unlike surface oxygen treatments, the conforming gel reaches the deeper tissue layers where deficiency is most severe.

Vascularization can take weeks in a healing wound. Brief pulses of oxygen are insufficient to sustain the biological processes needed across the full healing period. The new system provides continuous oxygen through the entire repair timeline.

The choline component adds a secondary benefit. Choline modulates immune responses and reduces excessive inflammation. Chronic wounds are often overwhelmed by reactive oxygen species - unstable molecules that damage cells and prolong inflammation. By providing stable oxygen while helping calm this immune overreaction, the gel addresses two aspects of wound pathology at once.

Animal model results

The team tested the system in diabetic and aged mice, chosen because their wound biology closely parallels that of older humans and diabetic patients. Without treatment, injuries in these animals typically failed to close and were often fatal. With the oxygen-generating patch applied and replaced weekly, wounds closed within approximately 23 days and the animals survived.

The principal limitation is that all testing was conducted in animal models. Diabetic and aged mice provide a reasonable approximation of human chronic wound biology, but the geometry, depth, infection dynamics, and immunological complexity of human wounds differ substantially. Human trials will be necessary to establish clinical safety and efficacy. The practical challenge of maintaining a gel-based electrochemical patch in reliable contact with a wound over weeks in a mobile patient also has not yet been evaluated.

"There are bandages that absorb fluid, and some that release antimicrobial agents," said Prince David Okoro, UCR bioengineering doctoral candidate and co-author. "But none of them really address hypoxia, which is the fundamental problem. We are tackling that directly."

The Noshadi lab sees broader applications in tissue engineering: supplying oxygen to thick, lab-grown tissues and organs, where diffusion alone cannot reach the interior once tissue exceeds a few millimeters. A system generating oxygen electrochemically within a biomaterial matrix could enable growth of functional tissue constructs previously limited by this oxygen barrier.