Every year, millions of people undergo surgery worldwide and the procedures require tissue sealing and wound closure. Mechanical fixation by stapling and suturing provides a reliable, cheap, and moderately fast method of address tissue fixation, yet there are drawbacks known. For instance, there is a risk of damaging the tissue and development of infections. Material scientists from Nanyang Technological University in Singapore have invented a new type of surgical glue that could boost wound healing by joining blood vessels and closing wounds faster.
CaproGlu for tissue mending
Their study, which appeared in journal Biomaterials, highlights that the team sought for a multipurpose platform for tissue mending because there’s a clinical need for a strong tissue adhesive with elastomeric material properties. They called their experimental material as CaproGlu. It is made up of two main ingredients: an organic molecule called diazirine and an FDA-approved biodegradable polymer called polycaprolactone. The diazirine material forms strong bonds when activated by a low dose of ultraviolet (UV) light.
The material scientists from NTU and clinicians from Singapore General Hospitals (SGH) demonstrated in animal experiments that their glue can bond soft tissue, including blood vessels and muscle, even when the surfaces are wet. Their new type of surgical glue can also be used to deliver pain relief and local anesthetic medication to tissues in the body, which are both useful during and after an operation and would lessen the need for pain relief medication after the operation.
Surgical bioadhesives vs. CaproGlu
According to the team, bioadhesives require two chemicals to be mixed before it can be used. With CaproGlu, however, it serves as a one-pot liquid gel solution that comes ready to use.
Senior Research Fellow Dr. Ivan Djordjevic and Associate Professor Terry W.J. Steele, lead authors of the study, pointed out that most surgical adhesives available in the market nowadays do not function in wet environments or water. So, to make the CaproGlu work on wet tissues, they engineered the materials to first remove the water from the surface, allowing adhesion.
CaproGlu’s adhesion strength
Assoc. Professor Steele went on to say that the unique benefit of the CaproGlu is that it has high adhesion strength even in a wet environment and is also biocompatible. This is why the material is suitable in medical and surgery applications. Compared to other commercial bio-adhesives available in the market, the CaproGlu was found to be three to seven times stronger and is comparable with the shear strength of muscle tissue and collagen found in the human body.
During their experiment, the material scientists also used CaproGlu in combination with glue and applied it in sutures. Instead of the conventional eight stitches needed to joint the two ends of blood vessels in a rabbit, they only used four stitches. They were further able to wrap the vessel ends with a biodegradable mesh that is dipped in CaproGlu and cured it with a small dose of UV light. The purpose of this is to crosslink the amino acids on the surface of the tissue.
They likewise observed that the bleeding from the artery quickly after the procedure was like what appears in conventional stitches. Seven days later, the artery has completely healed, NTU media release reads. They believe that their “bio rubber” glue promotes faster pain relief and surgical recovery.
But are there side effects to the animal skin which had CaproGlu? The team answered no. It has been shown that their material is both biocompatible and safe as expected. The bioadhesives dissolve and then reabsorbs within weeks, which means the patient no longer needs to visit the hospital again for its removal.
The authors also said that the material they developed could be potentially less costly in terms of commercialization and production compared to those based on acrylate and proteins. The joint team hopes to conduct further animal experiments to better access the performance of the CaproGlu, such as in organic surfaces and on the bone.
Number of surgical procedures (per 100,000 population)
Surgical care is important for managing diverse health conditions, including obstructed labor, injuries, cardiovascular disease, and malignancy infections. The World Bank published some countries with the highest number of surgical procedures per 100,00 population. The list includes Columbia (27,385), Denmark (21,197), Belgium (20,712), Latvia (18,395), Sweden (15,228), Brazil (13,940), Austria (13,795), Spain (10,579), Australia (10,156), Isle of Man (9,770), and Estonia (9,684).
Meanwhile, the G4 Alliance, Harvard Medical School, and the German Global Surgery Association mentioned in its Global Surgery & Anesthesia Statistics that surgical care is essential to ensure healthy lives and promote well-being for all. It likewise addresses infectious conditions, injuries, and NCDs as a necessary component of Universal Health Coverage. Improvements in trauma, including essential surgery, can save up to 2 million lives in limited in low- and middle-income countries (LMICs).
Global surgical adhesives and sealants
The global surgical adhesives and sealants market was valued at US$1,993 million in 2016 and is expected to reach $3,794 million by 2023, according to Allied Market Research. The surgical adhesives and sealant market types include fibrin sealants, collagen-based, gelatin-based adhesives, urethane-based adhesives, polymeric hydrogels, and cyanoacrylates. These are applied in hospitals, clinics, and ambulatory surgical care centers.
The World Health Organization emphasized that in wound management, primary closure requires that the clean tissue will be approximated without tension. Then, leave skin sutures in place for an average 7 days but it can take longer if the healing is expected to be slow due to blood supply of a particular location, such as in legs or back, or the patient condition itself. The most common technique for closing skin wounds nowadays is through sutures or stitches. It is where the doctor uses a piece of surgical thread (suture) to sew the two ends of the skin together. In the past, surgeons used horsehair, pieces of plants, and animal tendons to create sutures. Today, they’re made from manmade or natural materials, like silk, nylon, or plastic.
Sutures, which are a convenient way of connecting wound edges and tissues, can become foreign bodies that may cause problems because of the incompatibility with suturing materials or when absorbable suturing materials show disintegration early. The versatility of CaproGlu shows promise as it enables both inorganic and organic composites for bioadhesive platforms in the future.