Adhesive Technology and Surgical Glues

There are over 230 million surgeries performed globally and at least 12 million severe wounds treated in the US alone. Staples and sutures are the primary materials used when closing the wounds. The advancement of technology has allowed the industry to take a closer look at improving these mechanical methods.

Research has been underway that aims at creating a biocompatible adhesive glue. The most common limitation when using glue is its inability to stick to wet surfaces. In fact, many manufacturers warn users that the adhesive may not be as potent on damp areas, therefore, the need to make sure the surface is as dry as possible. When it comes to surgery, this cannot be achieved because of the prevailing wet conditions. This means that conventional adhesive cannot be used in surgical procedures leading to the use of sutures and staples. 

The research has been conducted by Purdue University and established that adhesive proteins found in mussels could be transformed into glue that is not only biocompatible but is also not toxic. Although other research breakthroughs came up with an adhesive that could be used underwater, most were not safe to be used in human surgical procedures and did not have the required strength. This is because they were either not biocompatible or were toxic.

Mussels and sandcastle worms were the main inspiration behind this research. The protein compounds these creatures produce are potent sealants even in wet environments. They produce proteins containing amino acid 3 and DOPA (4- dihydroxyphenylalanine), which continually offer adhesion strength even underwater. The glue created from this technology was considered to be ‘smart’. It could modify to suit any environment. Applicants can alter the protein-based adhesive to suit any situation. This makes it easy to use the glue on different tissues. 

Surgical Adhesive Discoveries

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Purdue researchers created ELY16 which is a polypeptide with the characteristics of elastin. It is formulated by bringing together elastin, which is a protein with high levels of elasticity found in tissues and the amino acid tyrosine. Tyrosinase is later on added to ELY16 which converts the tyrosine in DOPA to form mELY16. The two compounds, ELY16 and mELY16, can be used in dry conditions, but when DOPA is modified, it constitutes an adhesive that can be used in wet states as well. Also, the modification enables the new compound to be tuned to different environmental conditions and tissue variations. Interestingly, mELY16 can be tuned to suit different tissue types and environments minimizes chances of developing irritation and inflammation. 

The primary consideration when making glues to be used in surgical procedures is the adhesive’s ability to work under moist conditions and remain nontoxic. In the adhesive produced during the research, DOPA was the determining factor. The adhesives without the compound DOPA did not have the required strength to be used as sealants in humid conditions. The protein compounds that contain tyrosine alone were weak, but when DOPA was introduced, they could work well even in very wet conditions.

It is also essential to analyze how well the protein compound functioned in the wet conditions, its strength and reaction to humid environments.

In the research, elastin was an essential compound because it made the application process possible even under water. It is also flexible and occurs naturally in tissues. The strength and stiffness of the elastin mimicking polypeptides can be modified to look like that found in the body tissue. This is achievable through cross-linking. 

For commercial application, mELY16 portrays the best adhesion properties and strength when used underwater. It can be manufactured in high amounts suitable for commercial use. The compound also depicts higher levels of biocompatibility because of the use of human elastin in the formation. 

High amounts of the polypeptide can be created from Escherichia coli. When the substance is exposed to varying temperature, salinity, and Ph, it coacervates to form a thick protein compound which contains the adhesive elements but in concentrated forms. The compound is denser than water meaning that it cannot disperse.

To measure the viability and compatibility of the adhesives, mouse cells were used. The NIH/3T3 fibroblasts mouse cells were used to measure the toxicity levels. Also, the mouse cells ability to grow and retain their structure even when new compounds are introduced was observed during the research. Viability was also a critical observation where the NIH/3T3 fibroblasts cells were placed on ELY16 and mELY16 compounds for 48 hours to determine their behavior and survival. In all the tests, the viability was observed to be over 95%. 

More research is underway to ascertain how the compounds can be used in human tissues successfully.