- Formulation, Characterization, and in vitro Evaluation of Quantum Dots Loaded in Poly(Lactide)-Vitamin E TPGS Nanoparticles for Cellular and Molecular Imaging

Abstract

Fluorescent semiconductor nanocrystals, also called quantum dots (QDs), havebeen widely used and investigated in the fields of analytical chemistry andbioengineering, especially in fluorescent labeling for both in vivo cellular andmolecular imaging and in vitro assay detection. Applications of QDs includeserving as specific markers for cellular and molecular structures, tracing cellline age, monitoring physiological events in live cells, measuring cell motility, andtracking cells in vivo. Comparedwith the organic dyemolecules, QDs have severaladvantages. Organic dye molecules have narrow absorption bands which make itdifficult to excite multiple colors with a single excitation source. The emissiondensity of organic dye molecules relies on the environment. They could notoffer long-term photostability. They suffer from fast photobleaching and broad,overlapping emission lines (Gerion et al., 2001). The biological applications ofthe traditional organic dye are thus limited. Instead, QDs give several interestingand powerful optical properties, such as tunable emission from visible toinfrared wavelengths by changing their size and composition, broad excitationspectra with higher absorption coefficients, high quantum yield of fluorescence,stronger brightness and photostability, and high resistance to photobleaching.All those features have attracted tremendous interest in exploiting biomedicalapplications of QDs (Alivisatos et al., 2005; Ballou et al., 2004).