Origami Patch
Many operations today are performed using minimally invasive procedures, in which a small incision or puncture is made, through which cameras and surgical instruments are inserted to remove tumors and repair damaged tissues and organs. Minimizing the incision results in less pain and shorter recovery time compared to open surgery.
With all the development and technology of minimally invasive surgery, doctors may face problems at the stage of suturing internal wounds and ruptures.
Engineers at the Massachusetts Institute of Technology have developed a medical patch that can be placed around miniature surgical instruments and delivered through the respiratory tract, intestines or surgical incision to treat internal injuries. When dry, the patch resembles a folding film, similar to origami paper. Upon contact with wet tissues or organs, it turns into an elastic gel and can stick to the damaged area.
Unlike existing surgical adhesives, the new patch is designed to resist infection by contact with bacteria or body fluids. Over time, the patch decomposes safely and is removed.
You can watch the video on YouTube.
The researchers collaborated with practicing surgeons to optimize the design of the patch for clinical use, and they suggest that the new bioadhesive material allows it to be injected using minimally invasive surgical instruments that the surgeon controls directly or remotely using a medical robot.
The new patch can be used to restore perforation after colonoscopy or to heal parenchymal organs or blood vessels after injury or elective surgery. Instead of performing a completely open surgical access, it will be possible to insert a patch with which to close the wound inside the body, at least for a sufficient time for healing.
Multi-layer protection
Bioadhesives, which are currently used in minimally invasive operations, are available mainly in the form of biodegradable liquids and adhesives that can be applied to damaged tissues. But when these adhesives harden on a softer surface, an imperfect seal is created. Blood and other biological fluids can contaminate the glue, preventing successful adhesion to the damaged area. The glue can also dissolve before the injury heals completely, and after application – provoke an inflammatory reaction with the subsequent formation of scar tissue.
Taking into account the shortcomings of existing materials, the group sought to develop an alternative that would meet all functional requirements. The patch should adhere tightly to the wet surface of the damaged area, not bind with liquids until reaching the destination, and after applying to the damaged area, resist bacterial infection and excessive inflammation.
The origami patch meets all three requirements thanks to its three-layer structure. The middle layer is the main bioadhesive made of a hydrogel material with N-hydroxysuccinimide (NHS) inclusions. Upon contact with a wet surface, the adhesive absorbs the surrounding moisture and becomes elastic, taking the form of a fabric. At the same time, NHS esters in the composition of the middle layer of the patch form strong covalent bonds with compounds on the surface of the tissue, creating a tight contact between the two materials. The main layer is covered with protective materials on both sides. The lower one contains silicone oil, which prevents the patch from sticking to other surfaces when moving around the body. When the glue reaches its destination and is pressed lightly against the damaged fabric, the silicone oil is squeezed out, allowing the glue to attach to the fabric. The top layer of the patch consists of an elastomeric film coated with zwitter-ion polymers – molecular chains consisting of positively and negatively charged ions that attract the surrounding water molecules to the surface of the elastomer. Thus, the outward-facing layer of the patch forms a water-based film as a barrier against bacteria and other pollutants.
In a series of demonstrations, the researchers showed that the new bioadhesive patch adheres firmly to animal tissue samples even after they have been immersed in various liquids, including blood, for a long time.
They also used an origami technique to fold a patch around tools commonly used in minimally invasive surgeries. These instruments were inserted into the trachea, esophagus, aorta and intestines of animals. By pumping a balloon catheter or applying light pressure to a surgical stapler, the researchers were able to attach the patch to damaged tissues and organs and found no signs of infection on the surface or near the patch-covered area for one month after application.
The researchers suggest that the new bioadhesive can be made in a pre-folded form, and surgeons can easily place it around instruments, including for robotic surgery.
Article by S.J.Wu et al. A Multifunctional Origami Patch for Minimally Invasive Tissue Sealing is published in the journal Advanced Materials.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on MIT News: An origami-inspired medical patch for sealing internal injuries.