What is an adhesive?
An adhesive is something used to stick things together.
What makes something stick?
Two basic forces involved in sticking one thing to another are adhesion and cohesion. Adhesion is a force that causes different things to stick together, while cohesion is the force that causes similar things to stick together. Adhesive forces involve van der Waals forces. Van der Waals forces are attractive interactions at the atomic and molecular level but are much weaker than covalent and ionic bonds.
How could tannic acid be antimicrobial?
One possible antibacterial mechanism of tannic acid was reported as the interactions of tannic acid with bacterial cell wall leading to the complexation with cell wall protein and membrane disruption metal ions.
Why antimicrobial activity is necessary for bioadhesive?
A valuable tool for wound-healing and surgical procedures is tissue adhesives which can bind tissues together and allow them to regrow. Due to the potential for infection, it is desirable for these adhesives to have antibiotic properties.
Recently, researchers at Pennsylvania State University, Zhejiang Wanli University, Harbin Engineering University, and Jiangxi Provincial Children’s Hospital used PLGA from PolySciTech to act as a biocompatibility control for testing the cytotoxicity of their developed systems. This research holds promise to improve would healing and prevent infections.
What is the use of bioadhesives?
Tissue adhesives play an important role in surgery to close wounds, seal tissues, and stop bleeding, but existing adhesives are costly, cytotoxic, or bond weakly to tissue.
Inspired by the water-resistant adhesion of plant-derived tannins, we herein report a new family of bioadhesives derived from a facile, one-step Michael addition of tannic acid and gelatin under oxidizing conditions and crosslinked by silver nitrate. The oxidized polyphenol groups of tannic acid enable wet tissue adhesion through catecholamine-like chemistry, while both tannic acid and silver nanoparticles reduced from silver nitrate provide antimicrobial sources inherent within the polymeric network.
Any benefits?
Yes, many.
Low-cost
Readily scalable.
Eliminate the concerns of potential neurological effect due to the inclusion of dopamine.
Controllable degradation (up to 100% degradation within a month).
Considerable wet tissue adhesion strengths (up to 3.7 times that of fibrin glue).
Excellent cytocompatibility.
Antibacterial and antifungal properties.
How better is this from prevalent bioadhesives?
Compare to mussel-inspired bioadhesives that use expensive dopamine or DOPA as functional moieties, our polyphenol-based Gel-TA tissue adhesives utilize tannic acid as an abundant and low-cost raw material and eliminate the concerns of potential neurological effect brought by dopamine.
The innate properties of tannic acid as a natural phenolic crosslinker, molecular glue, and antimicrobial agent warrant a unique and significant approach to bioadhesive design.
References:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6328059/
https://communities.acs.org/people/jgakinainc/blog/2018/03/23/plga-from-polyscitech-used-in-development-of-tannin-inspired-antimicrobial-bio-adhesives.
Author: Ms Vindhya Regonda, Editorial Chair, ACS-BCP SC
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