Review accepted: A Bioactivity Matrix for Antimicrobial Activities of Chitosans: A review

Today, another manuscript that has been really long in the making has been accepted for publication in the renowned International Journal of Biological Macromolecules. We started during the pandemics to work on a review which we had long thought overdue but which was simply too too much effort to realise: thoroughly reviewing the available literature on structure-function relationships of the antimicrobial activities of chitosans, extracting the data presented, and generating a bioactivity matrix to visualise the results. Katharina Eickelpasch and Dr. Carolin Richter took the lead, and our alumnae Dr. Neeraja Chilukoti, Dr. Sruthi Sreekumar, and Dr. Philipp Lemke joint the team. All in all, we looked at roughly 7,000 papers! Most of them did not give sufficient structural details on the chitosans used, and many were of poor quality, but we found enough to come up with a tentative picture. It agrees with the often-mentioned general assumption that small chitosan polymers of low fraction of acetylation have the highest antimicrobial activity but surprisingly, the effect was a lot less clear than expected based on the few reviews we found that mentioned the topic at all. The most obvious conclusion of the review is that systematic investigations using series of well described chitosans under standardized conditions will be required to obtain more convincing insights into how the structure of chitosans determine their antibacterial and antifungal activities. Such investigations are now in progress, so there will be follow-ups!