When medical devices such as pacemakers are implanted in the human body, it usually triggers an immune response, leading to the formation of scar tissue around the implant. Fibrotic scars may interfere with the functionality of the device. According to a study published in Nature on the 22nd, engineers at Massachusetts Institute of Technology found a simple and universal method: coating a layer of hydraulic adhesive on the equipment can avoid fibrosis and prevent equipment failure. This method can not only be used for pacemakers, but also for implantable devices for drug delivery or cell therapy. Researchers at the Massachusetts Institute of Technology have stated that people hope to develop an implanted device that makes the immune system "invisible" without hindering its therapeutic or diagnostic functions. Now with this type of invisibility cloak, there is no need for additional medication or special polymer materials. The so-called "invisibility cloak" is made of hydrogel, in which the cross-linked polymer is polyacrylic acid (an absorbent material), which can quickly absorb moisture in wet tissue. After water is absorbed, the NHS ester chemical groups embedded in polyacrylic acid will form strong bonds with the proteins on the surface of the tissue. This process only takes about 5 seconds. To test the effectiveness of this adhesive, researchers applied it to a polyurethane device and implanted it into the abdominal wall, colon, stomach, lungs, or heart of rats. A few weeks later, these devices were removed and no obvious scar tissue was found. Experiments conducted on other animal models have also shown the same effect: no matter where the adhesive coated device is implanted, there was no fibrosis for up to 3 months. Researchers analyzed the immune response of animals using RNA sequencing and fluorescence imaging, and found that when devices with adhesive coatings were first implanted, immune cells such as neutrophils began to infiltrate the area and launch attacks. However, before scar tissue forms, the immune system quickly "stops working". Other experiments have shown that there is a certain mechanical interaction between the adhesive and the tissue, which can prevent the immune system from attacking. (Lai Xin She)