Bioimaging probes

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. 

Luminescence Photoluminescence of rare earth oxide nanocrystals is one of their most significant properties of interest for applications. The photoluminescence features of rare earth doped nanomaterials have been reviewed by Liu and Chen in an earlier chapter (Liu and Chen, 2007b). Therefore, we only review some related aspects, such as the major variations in the luminescence features of nanophased rare earth oxides, the application of rare earth doped nanocrystals as multicolor phosphors and as bioimaging probes. 

Luminescent Rare Earth Complexes as Chemosensors and Bioimaging Probes... 

Because there are many reports concerning TRF measurement in immunoassays [5-9], we focus herein on the use of rare earth complexes as luminescent chemosensors and bioimaging probes. 

Rare Earth Luminescent Chemosensors as Bioimaging Probes ofZn ... 

Zinc (Zn +) is the second most abundant metal ion after iron in the human body, and plays critical roles in regulating gene expression, enzyme regulation, and neurotransmission [90]. Zn + is also known to be responsible for the formation of amyloid plaques during the onset of Alzheimer s disease [91], At present, there is considerable interest in the development of Zn +-selective luminescence chemosensors as bioimaging probes [92, 93],... 

Laboratory of Bioimaging Probe Development, Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A STAR),... 

Iridium metal compounds have shown some remarkable effects recently for luminescent properties such as very high photoluminescent quantum yields [27, 29, 44] and high stability [46]. Two reviews [2, 4] have recently reported on phosphorescent heavy-metal complexes (Re, Ru, Os, Ir, and Rh) as bioimaging probes, including their photophysical properties, cytotoxicity, and cellular uptake mechanisms [2], and on transition metals (Ir, Re, Ru) in fluorescent cell imaging applications such as uptake and toxicity [4], respectively. 

SOLID-PHASE SYNTHESIS OF DYES AND THEIR APPLICATION AS SENSORS AND BIOIMAGING PROBES... 

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