Paper published: Biotechnologically produced chitosans with nonrandom acetylation patterns differ from conventional chitosans in properties and activities

Today, the main paper of the doctoral theses of Dr. Sruthi Sreekumar, Dr. Jasper Wattjes, and Dr. Anna Niehues, who share first-authorship, also containing some essential data from the doctoral thesis of Dr. Tamara Mengoni, has finally appeared in the journal “Nature Communications ”. The work, which was a central part of the European research project Nano3Bio , was performed in the groups of Prof. Bruno Moerschbacher and Prof. Francisco Goycoolea, mostly while the latter was still in Münster, some also after he moved to Leeds in the UK. Some important measurements were done in Copenhagen in the lab or Dr. Ana Mendes, and Prof. Ed Morris, who sadly passed away in 2021, supported us in the interpretation of some of the analytical data. For more than 25 years, we have been working on understanding structure-function relationships of chitosans, these most fascinating and most promising of biopolymers. In collaboration with chemists who were able to control the chain length of the polymers and the amount of acetic acid residues attached to it, we had found how these two structural parameters are influencing bioactivities of chitosans, such as their antimicrobial or plant strengthening effects. Such well-characterised ‘second generation’ chitosans are currently revitalising chitosan applications for e.g. agriculture or cosmetics, but they still failed to perform well in biomedical applications, such as for scar-free wound healing or drug, gene, or vaccine delivery. We hypothesised that we need to control also the distribution of the acetic acid molecules along the sugar polymer, but the chemists told us that this is not possible. So we had to come up with a biotechnological process making use of nature’s own tools to produce chitosans. But this was more difficult than expected and it took us many years and trials before finding out that we have to use these tools in “reverse gear” to be successful. This now gives us control over this third structural parameter of chitosans, and we are sure this is opening the door towards ‘third generation’ chitosans which will allow to finally harvest the promises of these precious molecules for biomedical exploitation. Who knows, perhaps your next mRNA-vaccine will be delivered straight to your nasal mucosa making use of these chitosans for targeted delivery to the immune system.