Phosphorescent porphyrin probes in biosensors and sensitive bioassays

Platinum(II) and palladium(II) complexes of porphyrins and related tetrapyr rolic pigments emit strong phosphorescence at room temperatures, which is c haracterized by long lifetimes falling into the sub-millisecond range and l ong-wave spectral characteristics. These features make the dyes useful as p robes for a number of bioanalytical applications, particularly those employ ing time-resolved fluorescent detection. They can provide high sensitivity and selectivity, together with rather simple instrumental set-up, A number of analytical systems are now under development that are based on the use o f phosphorescent porphyrin probes. Experimental results are presented on th e following systems: (i) fibre-optic phosphorescence lifetime-based oxygen sensor on the basis of hydrophobic platinum-porphyrins and development of a dvanced sensing materials and prototype instrumentation; (ii) practical app lications of the optical oxygen sensor, including a sensitive immunosensor that employs glucose oxidase labels, a rapid screening method for cell viab ility in microtitre-plate format, non-destructive measurement of oxygen in packaged foods and reagentless biosensors for metabolites (glucose; lactate ); and (iii) the use of water-soluble platinum- and palladium-porphyrins as labels for ultra-sensitive time-resolved phosphorescence immunoassays.