Nicholas A. Kotov, University of Michigan, Ann Arbor
Written by Xun Gong
Investigation into biological activity of one-dimensional nanoparticles has increased recently. However, given that 70% of such studies involve metals, there is a lot of room for the study of carbon structures. By oxidation of graphene sheets and then conjugation of amino acids via EDC/NHS, graphene quantum dots (GQDs) can be created with interesting bioactive chiral properties.
Through circular dichroism (CD), the chiral activity of the molecules was studied and it was found that it is not electronic coordination but geometry resulting from L or D amino acid conjugation that results in the overall differential response in CD.
In the biological context, toxicity studies with HepG2 liver cells show that D-cysteine GQD show increase toxicity as compared to its L counterpart. Through simulation, it was found that D-GQD has relatively increased ability for biological membrane penetration.
One potential application of these particles is in the case of biofilm prevention. Biofilms are protective nanostructures formed by bacteria in living systems, thus their prevention is an important area of research. These chiral GQDs were applied to biofilms and were able to prevent and stop biofilm formation. One explanation is that chiral GQDs exhibit a form of biological mimicry, replacing components of the biofilm nanostructure. Work is still ongoing concerning the relative activity of each chiral component.