Insight into carbon quantum dot–vesicles interactions: role of functional groups

Understanding carbon quantum dot–cell membrane interaction is essential for designing an effective nanoparticle-based drug delivery system. In this study, an attempt has been made to study the interaction involving phosphatidylcholine vesicles (PHOS VES, as model cell membrane) and four different carbon quantum dots bearing different functional groups (–COOH, –NH(2), –OH, and protein bovine serum albumin coated) using various tools such as PL behavior, surface charge on vesicles, QCM, ITC, TEM, LSV, and FTIR. From the above studies, it was observed that the –NH(2) terminating carbon dots were capable of binding strongly with the vesicles whereas other functional groups bearing carbon dots were not significantly interacting. This observation was also supported by direct visual evidence as shown by transmission electron microscopy, which shows that the polyethyleneimine carbon dot (PEICD) bearing –NH(2) functionality has greater affinity towards PHOS VES. The mechanistic insight presented in the paper indicates greater possibility of higher H-bonding, signifying better interaction between –NH(2) functionalized carbon dots and PHOS VES supported by FTIR, QCM, ITC and TEM. Moreover, the transport of neurotransmitters (which are generally amine compound) in neurons for cellular communication through synapse is only possible through vesicular platforms, showing that in our body, such interactions are already present. Such studies on the nano–bio interface will help biomedical researchers design efficient carbon-based nanomaterial as drug/gene delivery vehicles.