Although many surgical procedures can now be performed laparoscopically (through a small incision in the skin), it's still difficult to seal up internal injuries in this manner. MIT is developing a way of doing so, though, that's inspired by origami.
At the heart of the experimental new system are thin patches that are folded around the end of existing laparoscopic tools. Once that tool reaches the injured organ or muscle, the patch is pressed into place over top of it, unfolding as it does so. It then protects the biological tissue and holds it together while the injury heals, eventually harmlessly biodegrading.
Each patch has a paper-like consistency before entering the body, and is made up of three layers of material. The middle layer is a bioadhesive hydrogel containing compounds known as NHS esters. When exposed to a wet surface, the gel absorbs moisture, becoming soft, pliable and elastic. This allows it to be molded onto the contours of the biological tissue, while the esters form strong bonds with compounds in that tissue's surface.
The bottom layer (which is on the outside while the patch is folded) is coated with silicone oil. This keeps it from sticking to other surfaces in the body, before reaching its target. Once it has reached that target, pressure applied by the laparoscopic tool squeezes the oil out, allowing the adhesive middle layer to make contact.
The top layer (which is on the inside when folded, but on top once the patch has been applied) is made up of an elastomer film containing zwitterionic polymers. Negatively and positively-charged ions in those polymers draw in water molecules, allowing the film to become a water-based skin-like barrier that keeps out bacteria and other microbes.
In tests conducted so far, a laparoscopic stapler and a balloon catheter have been used to transport the patches through the trachea, esophagus, aorta, and intestines of pigs. By applying pressure to the stapler's "jaws" or inflating the balloon, the researchers were subsequently able to apply the patches to torn tissue. A month later, there were no signs of infection at the wound sites.
The scientists now envision the patches being manufactured in a variety of pre-folded configurations, each one designed to fit over the end of a specific tool.
A paper on the research, which was led by Prof. Xuanhe Zhao, was recently published in the journal Advanced Materials. The patch technology is demonstrated in the video below.
Source: MIT
