Fluorescent biological probe

Figure 5.7, (a) Widely used biological probes of the TICT type. 4, s4 s7> (b) TICT compounds with dual fluorescence and interesting properties amenable to tailor-making of fluorescence probes. Functionalization and inclusion in larger molecular assemblies is easily possible, e.g., at the positions indicated by R. This holds especially for esters and amides which have been used as probes in large polymers 97-1011 or in TICT-labeled cyclodextrins.(l49)... 

The use of fluorescent dyes in biological probes and sensors is covered in some detail in Chapter 3 (section 3.5.6). Because there are marked solvatochromic effects on the luminescent spectra of many fluorophores, this phenomenon is utilised to tune their performance and application in biological and other systems. 

Hemicyanines are polymethines with an ammonium salt at one end of the chain. Typically these can be pyridinium (3.30), indolenium (3.31a, X = C(CHj)2) and ben-zothiazolium (3.31b, X = S) derivatives. The pyridinium derivatives fluoresce in the long wavelength red region, whilst the others are in the near-infrared, which is a very useful property for certain laser dye outlets and in fluorescent imaging in medical diagnosis and biological probes. 

Robertson KL, Yu L, Armitage BA, Lopez AJ, Peteanu LA. Fluorescent PNA probes as hybridization labels for biological RNA. Biochemistry 2006 45 6066-6074. 

An optical method for monitoring the concentration of general anaesthetics and other small organic molecules in biologically interesting systems has been based on phase sensing of a fluorescent hydrophobic probe . Phase transitions in lipid membranes are detected by this method. The technique shows promise. 

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