Biomaterials-associated infections have become one of the most devastating medical complications. This problem is expected to escalate with the increasing use of man-made materials and devices such as catheters, cardiac pacemakers, and prosthetic implants. The inhibition of microbial colonization and subsequent biofilm formation is crucial for the prevention of such infections, and antimicrobial coatings offer a possible solution. However, this strategy is fraught with a number of challenges such as cytotoxicity and stability in the biological environment. Moreover, the presence of an antimicrobial coating may interfere with the intended biological functions of the biomedical device. Our work focusses on the development of antimicrobial coatings based on natural polymers for biomedical devices. These coatings have minimal cytotoxicity and are stable under autoclaving and mechanical forces expected during applications. In our presentation, we will describe how two natural polymers, chitosan and agarose, can be modified to form stable coatings on biomaterials. The antimicrobial mechanisms of these two natural polymers are different. Chitosan and its derivatives, in particular quaternized chitosan, are bactericidal and kill bacteria on contact. Such coatings are useful when the bacterial load is low, such as inhibiting touch contamination or contamination by aerosolized bacteria. However, accumulation of dead bacteria on the bactericidal coating over the course of exposure would result in blanketing of the active groups and the coating efficacy would eventually be compromised. Furthermore, chitosan and its derivatives have strong interactions with proteins which would lead to fouling of the surfaces for in vivo applications. Agarose on the other hand, cannot kill bacteria but its antifouling property is highly effective in reducing bacterial biofilm formation (by more than 2 orders of magnitude), and cell and platelet adhesion as well as protein adsorption (by ≥90%). The challenges faced by these coatings in the biological environment and further functionalization of these coatings for specific biomedical applications will be discussed.

Antimicrobial coatings for biomedical applications: Challenges and opportunities offered by natural polymers

249th National Meeting (2015)

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