Nanopolysaccharide Interaction with Bacteria—Effect of Surface Functionality

The interaction between different nanopolysaccharides and <i>E. coli </i>was evaluated by exposing E. coli to cellulose nanocrystals (CNC), TEMPO-oxidized cellulose nanofibrils (T-CNF) and ligno-cellulose nanocrystals (L-CNC). The observations of the bacteria cultures showed that none of the films had a cytotoxic effect over the <i>E. coli </i>when in indirect contact. Nevertheless, T-CNF and L-CNC, showed cytostatic effect on the growth of the cells, with T-CNF being the most prominent. The nanomechanical properties and interacting forces between the nanopolysaccharide film surfaces and the <i>E. coli </i>were studied using in situ PeakForce quantitative nanomechanical mapping (PFQNM). The PFQNM results demonstrated that the different types of nanopolysaccharides affect in site selectivity of the films against cell adhesion, and that all the studied samples altered the nanomechanical properties of cell envelops in different ways. The surface morphology of <i>E. Coli </i>cells was affected when in direct contact with the nanopolysaccharide films during incubation, except for <i>E. coli </i>cells attached to the CNC films. For all the cases, a stiffing effect was observed on the cell walls (based on the DMT modulus) after exposure to the nanopolysaccharide surfaces; being lowest for CNC compared to T-CNF and L-CNC. It was not possible to determine any obvious effect on the bacterial cells exposed to CNC films, but in the case of T-CNF and L-CNC substantially decreased cell growth and reduced the adhesion force, corroborating the great potential as antibiofouling material and capacity to interact with cytoplasm leading to cell leakage and possibly cell death. Overall, these studies pave the path for understanding how different types of nanocellulose and nanochitin can be used to tailor bacterial inhibition/proliferation properties on different materials.