Detection of human serum albumin by a photoinduced fluorogenic reaction

9,10-anthraquinone (AQ), a photochemically reactive substrate, has been conjugated together with human serum albumin (HSA), and the photoinduced fluorogenic reaction of the HSA-AQ conjugate was studied. This conjugate shows a greatly enhanced photochemical fluorimetric activity compared with that of free AQ. The spectral characteristics of the photoreduction product of the HSA-AQ conjugate was investigated and large blue shifts in both the excitation and emission bands, compared with those of free AQ, were observed. The kinetic behavior of the photoinduced fluorogenic reaction and the effects of some experimental conditions were also investigated. The enhancement in the photoinduced fluorogenic reactivity of HSA-AQ was utilized in the sensitive detection of HSA by a simple in-sire photoinduced kinetic fluorimetric method. The calibration graph was linear over the range 0- 1.0x10^-6 mol/L HSA. The detection limit was 6.5x10^-10 mol/L HSA and the relative standard deviation was 2.7% for 6.0x10^-8 mol/L HSA (n=6).