Sensitive determination of protein using terbium-metalloporphyrin as a fluorescence probe in AOT microemulsion

The quantitative determination of biomolecules is a basic requisite in biochemistry, food analysis, and clinical analysis. In this paper, a highly sensitive and selective fluorescence method was developed to determine proteins using a metalloporphyrin, terbium-meso-vanillin-metalloporphyrin (T(3-MO-4HP)P-Tb), as a probe. In the presence of bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) microemulsion, protein could enhance the fluorescence intensity of porphyrin. The experimental conditions, such as pH, medium, and probe concentration, were investigated. Under the optimal conditions, the enhanced fluorescence intensity was in proportion to the concentration of proteins in the range of 0.12-6.75 μg·mL− 1 for bovine serum albumin (BSA), 0.14-12.00 μg·mL− 1 for ovalbumin (Ova) and 0.15-7.60 μg·mL− 1 for human serum albumin (HSA). The detection limits were 0.075 μg·mL− 1 for BSA, 0.080 μg·mL− 1 for Ova and 0.087 μg·mL− 1 for HSA, respectively. The proposed method was also applied to the determination of protein in real samples with satisfactory results. This fluorescent method with high sensitivity and low detection has potential application in food science for the determination of proteins.