Scientists have developed a new therapeutic gel to fight rheumatoid arthritis, that can be used to absorb extra fluids in swelling joints and release drugs.

Rheumatoid arthritis is a long-term disease that causes inflammation and deformity of the joints.In this autoimmune condition, the body's immune system attacks the soft tissue of the joints, leading to an accumulation of synovial fluid. Excess of this fluid causes swelling and pain.Current rheumatoid arthritis treatments are based on anti-inflammatory drugs that relieve pain and inflammation.

However, the findings showed that the jelly-like material detects nitric oxide -- a gas with various physiological functions -- found in the immune cells of the inflamed joints. "Nitric oxide is like a double-edged sword. It regulates inflammation and protects our body by killing external pathogens. However, when in excess, it is toxic and may cause rheumatoid arthritis," said lead author KIM Won Jong from the Institute for Basic Science (IBS) at South Korea. Nitric oxide is a transient gas, which stays in circulation for less than 10 seconds, before binding to other molecules. It also causes other autoimmune diseases, cardiovascular diseases and cancer.

In the study, detailed in the journal Advanced Materials, the team developed a gel responsive to such fugitive molecules, using acrylamide as a base material and a new crosslinker to keep it in place. Unlike the monomeric form, polymeric acrylamide hydrogel has little toxicity and can contain a large amount of water. In addition, the cross-linking agent forms bridges between the acrylamide molecules creating a net, which can trap drug molecules inside.When nitric oxide cleaves to the cross-linking agent bridges, the gel changes its structure, frees the drug and absorbs new liquid, the researchers noted.