CHEMISTRY: Almost as Bright

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Science  07 Jan 2005:
Vol. 307, Issue 5706, pp. 18d
DOI: 10.1126/science.307.5706.18d

Tracking particles and cells in the fluorescence microscope is a key analytical technique in cell biology and materials science. Increasing demand has led to the synthesis and functionalization of new fluorophores and semiconductor nanoparticles (quantum dots). However, many fluorophores are readily photobleached and not very bright, whereas quantum dots require capping layers to prevent aggregation, and their synthesis requires harsh solvents and precursors.

Ow et al. have created a hybrid structure with an organic fluorophore covalently attached to a silica precursor, forming an organic core surrounded by a thin silica shell, which is then encapsulated using sol-gel chemistry to make particles 20 to 30 nm in diameter. Adding the outer shell of silica increased the brightness by a factor of 30. One reason is that the shell protects the fluorophore from solvent, which also increases its photostability. The silica nanoparticles are not quite as bright as similarly sized quantum dots, but they can be easily functionalized using the well-established and broad library of silane coupling methods. — MSL

Nano Lett. 10.1021/nl0482478 (2004).

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