Particle tracking carboxyl and transferrin conjugated quantum dots diffusion at living cell surface

摘要

Nanotechnologies and nanomaterials have gained much success in the fields of biological applications. In particular, quantum dots (QDs) are emerging as a revolutionary means for imaging and optical detection in opposition to conventional organic dyes. For their robust photostability, large extinction coefficients, and relatively small size, QDs present superior advantages in single molecules monitoring over long time period in living cell. The interaction between functionalized QDs and living cell is the primary problem of the QDs application in living cell. In this work, carboxyl and transferrin conjugated CdS QDs were evaluated using total internal reflect fluorescence (TIRF) microscopy and single particle tracking (SPT) techniques at living cell surface. The diffusion and binding were quantitively measured by mean square displacement (MSD) versus time plotting. To study the influence of different QDs surface on interaction between QDs and cell, dynamic characters of carboxyl and transferrin conjugated QDs were calculated respectively. The photonic characters of QDs were also investigated, considering that functionalized surface can lead to behavior altering of QDs under illuminating. Simultaneous imaging of several QDs with frame rates of up to 30 frames/s and localization accuracy of ～10 nm was present.