A novel method for preparing quantum dot nanospheres with narrow size distribution

Differently colored quantum dot (QD) nanoparticles are incorporated into bovine serum albumin (BSA) nanospheres by spray-drying followed by thermal denaturization, which is a rapid, highly efficient, large scale, and low cost method. Because the spray-dryer is equipped with an ultrasonic atomizer, most of the nanospheres are no more than 550 nm in diameter and a have narrow size distribution. Ultrathin sections (70 nm) of nanospheres are first prepared using a technique which is normally applied to cell sectioning. The section images show that the QD-BSA nanospheres are solid, and that the QDs are successfully dispersed inside the BSA nanospheres. The nanospheres emit bright fluorescence, and their fluorescence stabilities are not obviously changed compared with that of the QDs. This work provides a novel and simple method for preparing nanoscale spheres encapsulating differently colored QDs. We also present an ultrathin sectioning method for investigating the interior details of nanomaterials.