Biocompatible Quantum Dots for Intravital Kidney Imaging

Abstract

Quantum dots (QDs) are emerging alternatives to traditional dyes for fluorescence imaging applications. Quantum dots are attractive due to their photostability, broad excitation, narrow emission bands, high quantum yields and relatively long fluorescence lifetimes for contrast enhancement. We are interested in applying quantum dots (CdSe/ZnS) with biocompatible coatings for functional imaging of the kidney in vivo. Towards that end, we carried out experiments to characterize the bio- and photo-physical properties of CdSe/ZnS quantum dots with lipopolymer and aminoethoxy ethanol (AEE) coatings, and in vivo imaging of the kidney using surface coated quantum dots. We found that the fluorescence of the CdSe/ZnS quantum dots with surface coatings is enhanced in the presence of blood serum and it is serum concentration dependent. In addition, these surface coated quantum dots exhibit photo-induced fluorescence enhancement (PFE) and the PFE varies with specific surface coatings. Previously, PFE phenomenon is observed in CdSe quantum dots without surface coatings and has been studied under a number of different experimental conditions. To our knowledge, PFE of quantum dots with a surface coating has not been reported in the literature. For imaging application, we have developed protocols to use these surface coated quantum dots for intravital imaging in rodents and we are able to successfully acquire in vivo images of the kidney and perform kinetic measurements. Here, we summarize and discuss our results of the PFE property and in vivo imaging and characterization of these quantum dots. This work was supported by NIH DK077051 research award to W. Yu on in vivo kidney imaging.