The adsorption behaviour of carbon nanodots modulated by cellular membrane potential†
Carbon nanodots (CDs) are fluorescent nanomaterials that have attracted widespread attention for biomedical applications. Since different cells possess different membrane potentials, the influence of the trans-membrane potential on the adsorption behaviour needs to be explored extensively. It was found that fewer CDs can be adsorbed by depolarized cells with decreased membrane potential, as compared to hyperpolarized cells with enhanced membrane potential that promotes the adsorption of CDs. A similar adsorption trend was observed for two cell lines, namely NIH3T3 and MCF-7. Since phosphocholine is the primary component of the cellular membrane, the adsorption behaviour of CDs is further complemented by the interactions between CDs and three kinds of liposomes with different surface charges via the thermodynamic and kinetic perspectives. The adsorption constants between negatively charged CDs and liposomes are positively related to their membrane potential, which is similar to the adsorption rate constants. It was further found that the adsorption of CDs onto liposomes was initiated by electrostatic attraction forces. The membrane integrity and fluidity of liposomes exposed to CDs have also been characterized. The membrane potential of cells is, therefore, particularly important when predicting the relative cytotoxicity of CDs and developing CDs-based nanomaterials for biomedical applications.