The binding between three surface-active substituted 3H-indole fluorescence probes and bovine serum albumin (BSA) in aqueous solution was studied using fluorescence quenching. The binding constants of 3H-indole molecules with BSA were obtained. According to the F?rster resonance energy transfer theory, the distances between 3H-indole molecules and tryptophan of BSA were calculated. The results show that the oligoethyloxyethylene chain of 3H-indole molecules is longer, the binding between them is stronger, the energy transfer efficiency is higher, and the distance between tryptophan and 3H-indole is nearer.
