Adsorption behaviour of carbon nanodots modulated by cellular membrane potential

Carbon nanodots (CDs), as a kind of fluorescent nanomaterials, have attracted widespread attention for biomedical application. Since different cells possess different membrane potential, the influence of trans-membrane potential on the adsorption behaviour is required to be explored extensively. It is found that less amount of CDs can be adsorbed by depolarized cells with decreased membrane potential while hyperpolarized cells with enhanced membrane potential promoted the adsorption of CDs. Similar adsorption trend is 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 with the interactions between CDs and three kinds of liposome with different surface charge via the thermodynamic and kinetic perspective. The adsorption constants between negative charged CDs and liposome are positive related with their membrane potential, which is similar to the adsorption rate constants. It was further found that adsorption of CDs onto liposome is initiated by electrostatic attraction forces. Finally, the membrane integrity and fluidity of liposome exposed to CDs have also been characterized. So the membrane potential of cells is especially important, when prediciting the relative cytotoxicity of CDs and developing CDs based nanomaterial for biomedical application.