Fluorescence properties of albumin blue 633 and 670 in plasma and whole blood

We have determined the fluorescence characteristics of two long wavelength dyes, albumin blue 633 (AB633) and 670 (AB670), in plasma and blood to eval uate the possibility of making direct fluorescence sensing measurements in blood. Using binding and lifetime measurements we were also able to show th at these dyes bind selectively to human serum albumin (HSA) in plasma and b lood. By measuring changes in the mean lifetime of AB670 with changes in th e HSA concentration, we showed that lifetime-based sensing can be used to m onitor HSA concentrations using these albumin blue dyes. Anisotropy measure ments for AB633 and AB670 in plasma and blood revealed high anisotropy valu es for these dyes in these media. Exploiting these high anisotropies, we we re also able to determine HSA concentrations in plasma and blood mimics usi ng changes in AB670 anisotropy with HSA concentration. These results show t hat, apart from being able to make fluorescence measurements directly in pl asma and blood, it is possible to sense directly for specific plasma/blood components using fluorescent probes that bind preferentially to them. (C) 2 001 Society of Photo-Optical Instrumentation Engineers.