Researchers create fast-acting 'biorubber' surgical glue

A novel surgical glue has been developed by materials scientists at Nanyang Technological University (NTU) Singapore that can help join blood vessels and close wounds faster than current bioadhesives and may serve as a platform to deliver pain relief drugs.

Working with clinicians from Singapore General Hospital (SGH), the NTU researchers have published a paper in Biomaterials, demonstrating that the glue can bond soft tissues including muscle and blood vessels, even when their surfaces are wet.

CaproGlu is activated by a low dose of ultraviolet (UV) light that cures it in seconds, turning it from a liquid glue into a solid but flexible biorubber — a biocompatible material that can be resorbed by the tissue after a few weeks.

Animal studies showed that blood vessels can be rejoined with just four stitches and a mesh wrapper dipped in CaproGlu, compared with the usual eight stitches that are required for a reliable and unobstructed join. The authors estimate that this will reduce surgery time by 25%, as surgeons spend less time and effort stitching up blood vessels and tissues.

In these studies, CaproGlu was also used to deliver local anaesthetics or pain relief to tissues in the body, which may be useful both during and after an operation and would reduce the need for pain-relief medication to be administered afterwards.

Unlike current bioadhesives that need two chemicals to be mixed prior to use, CaproGlu is a one-pot liquid gel solution that comes ready to use.

Lead authors Associate Professor Terry WJ Steele and Senior Research Fellow Dr Ivan Djordjevic emphasised that most surgical adhesives available on the market do not work in water or wet environments as found in the human body.

“To make our light-activated glue work on wet tissues, we engineered our glue to first remove water from the surface and thus allow adhesion to the dehydrated surfaces,” Associate Professor Steele said.

“This unique advantage of being able to bond with high strength in a wet environment, as well as being biocompatible, is what makes CaproGlu so suitable to be used in surgery and medical applications.”

The adhesion strength of CaproGlu was compared to other commercial bioadhesives on the market and was found to be three to seven times stronger, and is on a par with the shear strength of collagen and muscle tissue found in the human body.

A big challenge for bioadhesives on the market today is to cope with the standard method by which surgical-grade equipment and disposables are sterilised using gamma irradiation.

The gamma sterilisation process destroys proteins and activates bonding in both acrylate and epoxy adhesives.

Unlike other surgical adhesives available on the market, CaproGlu’s protein-free formulation exploits new crosslinking chemistry unaffected by gamma sterilisation.

The light-activated bonding mechanism forms chain links to amino acids at the nanoscale level, even after several months of storage and gamma sterilisation, thus making CaproGlu’s production and commercialisation potentially less costly than those based on proteins and acrylates.

Image caption: Invented by Dr Djordjevic (L) and Associate Professor Steel (R), CaproGlu combines two ingredients into a single-component formulation that does not require additives. Image credit: ©NTU Singapore.