Quantum dots for bioimaging, cellular labeling and diagnostics

Research on semiconductor nanocrystals, known as quantum dots, has progressed substantially over the past two decades. These fluorescent particles have unique photophyscial properties such as broad excitation spectra with large Stokes shifts and narrow size-dependent emission spectra that prove to be advantageous over other molecular dyes. Additional unique optical properties like high quantum yield, high molar extinction coefficients compared to organic dyes, enhanced photo-bleaching resistance, and chemical degradation resistance are encouraging researchers to further explore the uses for quantum dots in fields like bioimaging and optical surgery. Improvements in reproducible synthesis and green synthesis in combination with reliable and accurate characterization have paved the way for diverse applications. Here in this chapter we discuss the synthesis, capping or coating strategies, and biofunctionalization methods that have been previously developed. We also review characterization of these various quantum dots as well as discuss current and future potential uses of quantum dots. Quantum dots have been used in everything from high resolution in vitro cellular imaging, in vivo deep tissue imaging for tumor targeting, multiplex optical biosensors for diagnostic use, to single-molecule intracellular trafficking studies. This exciting expanding field is burgeoning with activity and new applications as the research community is exploring these unique nanocrystals to fully elucidate all their uses and capture their full potential.