Fluorescence bioimaging

In conclusion, it should be noted that fluorene derivatives 16 and 22, with large two-photon absorption cross sections, high fluorescence quantum yields and high photochemical stabihty imder one- and two-photon excitation are outstanding candidates for various linear and nonhnear optical apphcations, especially 3D fluorescence bioimaging. 

The ease of handling tied to the high detection sensitivity of fluorescent lanthanide probes has led to their being used in base sequence analysis of genes, DNA hybridization assay and fluorescent bioimaging, apart from in immunoassay. They are rapidly replacing organic... 

K. Li, B. liu. Polymer encapsulated conjugated polymer nanoparticles for fluorescence bioimaging, J. Mater. Chem. 22 (2012) 1257-1264. 

Soga K. Development of NIR Fluorescence Bioimaging System through Polyscale Technology, Bunseki Kagaku, 58, 461-471 (2009). 

Zako T., H. Nagata, N. Terada, M. Sakono, K. Soga and M. Maeda, Improvement of dispersion stability and characterization of upconversion nanophosphors covalently modified with PEG as a fluorescence bioimaging probe, J. Mater. Set, 43, 5325-5330 (2008). 

The conversion of squaraine 19a to the rotaxane 18 D 19a causes a modest red-shift only in both absorption (10 nm) and emission (7 nm) but an approximately threefold decrease in quantum yield. The addition of two triazole rings (dye 19b) did not significantly alter the quantum yield of 17b (Table 4). A macrocycle-induced quenching effect was verified by fluorescence titration experiments adding aliquots of 18 to a solution of squaraine 17b in methylene chloride [58]. Treatment of the 18 d 17b psuedorotaxane system with the tetrabutylammonium salts of chloride, acetate, or benzoate leads to the displacement of squaraine 17b from the macrocyclic cavity and the nearly complete restoration of its fluorescence intensity. The 18-induced quenching of 17b does not support the utility of this system as a bioimaging probe however, the pseudorotaxane system 18 Z> 17b acts as an effective and selective anion sensor with NIR fluorescence. 

The squaraine rotaxanes based on the macrocycle 16b exhibit intense NIR absorption and emission maxima, and it should be possible to develop them into molecular probes for many types of photonic and bioimaging applications. In contrast, the squaraine fluorescence intensity is greatly diminished when the dye is encapsulated with macrocycle 18. The fluorescence is restored when a suitable anionic guest is used to displace the squaraine dye from a pseudorotaxane complex, which indicates that the multicomponent system might be applicable as a fluorescent anion sensor. 

Fig.l Schematic design of nanoparticie for bioimaging containing the fluorescent dye encapsuiated in an inorganic matrix Q surface modified with another sheii o and conjugated to biomoiecuies ... 

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