The Stokes shift (the difference between the spectral positions of the maxima of the absorption and emission spectra) for most fluorescent dyes are often very small, which poses problems such as cross-talk between different dye molecules. While most organic dyes exhibit moderate to high quantum yields, many are photolabile and undergo photobleaching during continuous excitation. Within the group of dyes, we could also include fluorophores that are part of a protein’s structure (such as phycobiliproteins and fluorescent proteins that can be genetically encoded). The most widely used fluorescent markers are organic dyes, such as rhodamine, coumarin, and cyanine dyes, and their derivatives. Unfortunately, most fluorescent markers do not possess all of these features. Furthermore, a suitable fluorescent marker should be conveniently excitable and detectable in the biological transparency window to avoid simultaneous excitation of endogenous fluorescent molecules, such as blood constituents, cofactors, and water. Ideal fluorescent nanoparticles should exhibit most, if not all, of the following features: (1) high sensitivity, down to the single molecule level, (2) high spatial resolution (with correspondingly small size at the nanoscale), (3) high molar absorption coefficient at the excitation wavelength with high fluorescence quantum yield, (4) absence of blinking and photo bleaching for real-time imaging, (5) robust surface chemistry, (6) biocompatibility, and (7) lack of toxicity. Over the past decades, efforts have been focused on the development of fluorescent nanoparticles to analyze complex biological processes, as well as to track and localize individual drugs, proteins, nucleic acids, and small molecules, ,.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |