Understanding Nanoparticle Drug Delivery from Rotational Dynamics and Behaviors of Functionalized Gold Nanorods on Live Cell Membranes

Yan Gu, Wei Sun, Gufeng Wang, Ning Fang
2011 Biophysical Journal  
Gold nanoparticles with distinctive surface properties share different interactions with the cell membranes, thus show different activities in drug delivery. We used gold nanoparticles themselves as non-blinking, non-photobleaching nanoprobes to study nanoparticle drug delivery. Unlike most single particle tracking experiments that studied the translational motions of particles, we tracked the realtime rotational behaviors of single gold nanorods on live A549 cell membranes. The rotations of
more » ... ferently functionalized gold nanorods are tracked constantly under a Differential Interference Contrast (DIC) Microscope at 200 frames per second. The time series of DIC intensities of the images reflect the rotational dynamics of the gold nanorods. The in-plane and out-of-plane rotations were characterized by calculating the correlation coefficients between bright part DIC intensities and dark part DIC intensities of the gold nanorod. The autocorrelations of the image contrast time-series were calculated, and the rotation characteristic times over time of observation were derived by a non-linear fitting. We found that on one hand, the rotational behaviors of gold nanorod probes are strongly related to the surface charges of the gold nanorods, such as positively charged gold nanorods (PEIs modified, TAT modified, and CTAB stabilized gold nanorods) show a stronger interaction with cell membranes than negative ones (tranferrin modified and carboxylic gold nanorods). On the other hand, specific surface functional groups and availabilities of receptors on cell membranes also contribute to the rotational dynamics of the gold nanorods (such as shown in the differences between transferring modified gold nanorods and carboxylic gold nanorods). This study of nanoparticle rotational diffusion on cell membranes will lead to better understanding of the mechanisms of drug delivery and provide guidance in designing the modification strategies for drug delivery agents under different circumstances.
doi:10.1016/j.bpj.2010.12.2771 fatcat:5phbp3ez6rfxnivaigbmeetb6m