Twisted Fibrils

In the project Twisted Fibrils – A Look into their Chiral Liquid Crystal Self-Assembly we investigated the fine nanoscale structures of cellulose and protein nanofibrils and developed new polarized optical microscopy techniques to study their liquid crystal phase behavior.

The resulting fine structural features of both the amyloid and cellulose nanofibrils are intimately linked to their processing conditions and surrounding physical conditions. We found direct evidence of a right-handed chirality on the single fibril level for the cellulose nanofibrils and could also show that the amount of right-handed twisting can be tuned by changing the average charge density on the fibrils where a higher amount of charge results in a higher twisted.

We were also able to show that the sharp discontinuities found along the cellulose nanofibril contours, sometimes called kinks, are a non-native feature in this system. The density of kinks is closely related to the processing conditions for the fibrils and increasing mechanical treatment during fibrillation was found to induce kinks. Using an acid hydrolysis process we were also able to show that the acid induced breakage into smaller cellulose nanocrystals occurs preferentially at positions of kinks.

This work was kindly supported by an ETH Career Seed Grant (SEED-43 16-1) and resulted in several scientific publications including reports in Nature Communications, ACS Nano, Biomacromolecules and Nanoscale.