Chemical modification of aminated condensed tannin: impact of quaternary ammonium, pyrogallol, and methylation modifications on antibacterial, antioxidant, and physicochemical properties

Abstract

In a world with a rapidly aging population and healthcare system growth, we are faced with the demand for multifunctional biomaterials capable of preventing implant-associated infections, supporting tissue regeneration, mitigating sterile inflammation, and reducing the burden on both patients and the healthcare system. Coatings made from polymers of natural origin have been under investigation by the scientific community for a long time, and their multifunctionality underscores the need for deeper exploration of biopolymers as biomaterials. Specifically, while non-polymeric polyphenolic compounds have been used by humanity for thousands of years and are today widely recognized for their antioxidant, antimicrobial, anti-inflammatory, and other favorable biological properties, their polymeric counterparts - condensed tannins - remain largely unexplored in the biomedical field. To date, biological performance studies conducted by our laboratory on a condensed tannin derivative, Tanfloc, demonstrate great potential for its use as a new biopolymer for implant coatings and other fields of biomedicine. However, the relationship between 'chemical structure' and 'biological activity' for this condensed tannin derivative remains poorly understood, particularly regarding how its polyphenolic nature and amino groups contribute to its biological performance. This work focuses on elucidating the role of key chemical groups in the aminated condensed tannin derivative Tanfloc by modifying its structure and evaluating the impact of modifications on physicochemical, antioxidant, and biological properties. Tanfloc was chemically modified using quaternization, galloylation, and permethylation to target its amino and polyphenolic moieties. Polyelectrolyte multilayer (PEM) sample implant coatings were then fabricated using these derivatives in combination with hyaluronic acid, using a layer-by-layer deposition method. Comprehensive characterization techniques were employed to assess the structural, chemical, and surface properties of both the modified powders and PEMs. This study provides insights into how specific chemical modifications influence the behavior of polyphenol-based biopolymers and how it can be employed in the design of multifunctional implantable devices.