Nanoparticle Binding As A Function Of Membrane Potential

Nanoparticles have initiated interest for their role in imaging and gene therapy such as their use in targeting cancer cells.  Before these nanoparticles can be used for cellular applications, it is important to study their role in cell binding. Cells have a membrane potential due to the difference in intracellular and extracellular ion concentration across the plasma membrane. A recent study has shown that nanoparticle binding can change the membrane potential. Using known methods of controlling the membrane potential can serve as a useful tool to address questions of interest. How does nanoparticle binding change as a function of membrane potential? In this study, two types of nanoparticles were used: nanoparticles containing a negative surface charge acquired from COOH and nanoparticles containing a positive surface charge acquired from NH₃. The extracellular potassium concentrations of cells were increased to remove the effect of the membrane potential and binding of nanoparticles were studied. Results showed that nanoparticles containing positive surface charge binded more to cells having no membrane potential. They appeared more bright under a wide-field microscope and showed a higher shift in intensity in flow cytometry. Additionally, nanoparticles containing negative surface charge binded less to cells with no membrane potential. There was a decrease in intensity for cell binding . It is possible that the decrease in intensity for COOH beads in a higher potassium concentration is due to its size. Thus experimenting with smaller COOH bead is warranted in the future.