Semiconductor Quantum Dots Surface Modification for Potential Cancer Diagnostic and Therapeutic Applications

Abstract

Semiconductor Quantum dots (QDs) have generated extensive interest for biological and clinical applications. These applications arise from their unique properties, such as high brightness, long-term stability, simultaneous detection of multiple signals, tunable emission spectra. However, high-quality QDs, whether single or core-shell QDs, are most commonly synthesized in organic solution and surface-stabilized with hydrophobic organic ligands and thus lack intrinsic aqueous solubility. For biological applications, very often it is necessary to make the QDs dispersible in water and therefore to modify the QD surfaces with various bifunctional surface ligands or caps to promote solubility in aqueous media. Well-defined methods have been developed for QD surface modification to impart biocompatibility to these systems. In this review, we summarize the recent progress and strategies of QDs surface modification for potential cancer diagnostic and therapeutic applications. In addition, the question that arose from QD surface modification, such as impact of size increase of QD bioconjugates after surface-functionalization or surface modification on photophysical properties of QDs, are also discussed.

Quantum Dots and Fluorescent and Magnetic Nanocomposites: Recent Investigations and Applications in Biology and Medicine

“…Due to the effects of quantum confinement, QDs possess distinct photophysical properties that give QDs tremendous advantages over the conventional organic fluorophores [16][17][18]. Traditional organic dyes exhibit chemical and photophysical limitations such as pH dependence, susceptibility to photo-bleaching, narrow absorption windows of wavelengths, asymmetric emission spectra broadened by a red tail, small Stokes shifts, and short excited state fluorescent lifetimes [17][18][19].…”

“…In contrast with the organic dyes and fluorescent proteins, QDs have distinct electronic and optical properties that comprise high quantum yield, broad absorption, large effective Stokes shifts, the ability to size-tune fluorescent emission as a function of core dimension, simultaneous excitation of multiple fluorescence colors, and high resistance against photo-bleaching and against photo-and chemical degradation [19,20]. QDs have great potential in many applications such as solar cells, light-emitting devices, and photobio-labeling technologies.…”

“…The unique optical properties of QDs make them appealing in vivo and in vitro in different biological and clinical applications, such as cell labeling [17,20], cell tracking, in vivo imaging, and DNA detection [19,21].…”

Optical Properties and In Vitro Biological Studies of Oligonucleotide‐Modified Quantum Dots

“…The emission wavelength is directly related to the particle size as larger particles will absorb lower energy, that is, longer wavelength photons [1]. Water-soluble CdTe-based QDs have attracted much interest in recent years for their potential applications in biological imaging especially, which consists in illuminating the cell membrane, the cytoplasm, or selected organelles using a fluorophore [2][3][4][5][6][7][8][9][10][11][12][13][14]. Choosing an appropriate combination of staining agents enables one to elucidate cellular structures or mechanisms by visualising them with a fluorescence or confocal microscope.…”

Characterisation of variables associated with the flight behaviour of the rust-red flour beetle (Tribolium castaneum)

“…Although UV rays may have contributed to the quenching, these insects are mainly crepuscular, and so would have had little exposure. This is, however, a problem for studies on diurnal insects and to resolve this problem QDs can be functionalized with chemical groups such as organic ligands that can enhance the photo stability of QDs (Wang et al, 2012).…”