Fluorescence Study On The Interaction Of Serum Albumin And Aluminum Reagents

Aurintricarboxylic acid (ATA) is an extensively used reagent in analytical chemistry, biochemistry and medical science, but its fluorescence properties has not been found in the literature. We studied the fluorescence spectra of ATA, and found that ATA solutions with pH 3 to pH 12 produce fluorescence when irradiated with ultraviolet rays. The maximum excitation wavelength and the maximum emission wavelength are 297nm and 409nm, respectively. An excellent linear relationship between fluorescence intensity and ATA concentration is observed. The linear range is 0.01 u g/mL-3 u g/mL, and the detection limit is 0.01 u g/mL. Using quinine bisulphate as a reference, fluorescence quantum yield of ATA is measured to be 0.16. Changing of fluorescence quantum yield of ATA along with excitation wavelength was investigated also.Bovine serum albumen (BSA) and human serum albumen (HSA) are commonly used in biochemical studies. However, their fluorescence quantum yields reported in the literature are not coincident. So, the fluorescence spectra and fluorescence quantum yields of BSA and HSA were studied in this work. The maximum excitation wavelength and the maximum emission wavelength of BSA are 280 nm and 340 nm, respectively, whereas the maximum excitation wavelength and the maximum emission wavelength of HSA are 280nm and 354nm, respectively. Using L-Tryptophane as a reference, fluorescence quantum yields of BSA and HSA are all measured to be 0.13. Influence of excitation wavelength and experimental conditions on thefluorescence spectra and fluorescence quantum yield were also investigated.Fluorescence quenching of BSA is observed when ATA is added into BSA solution, and at the same time, sensitizing fluorescence enhancement of ATA is found. This fact reveals that there is an interaction between BSA and ATA, and energy transfer between them has happened. Interaction mechanism of BSA with ATA is studied by using the fluorescence spectra of BSA-ATA system. According to the Forster non-irradiation resonance energy transfer theory, distance between the energy donor and accepter is calculated to be r =2.35 nm (R0=1.96 nm). Binding number and binding sites of ATA on BSA are deduced by fluorescence spectra of ATA at different concentrations of BSA. Effects of experiment conditions, such as concentration, pH, ion strength and surfactants are also investigated.