Study on the competitive reaction between bovine serum albumin and neomycin with ponceau S as fluorescence probe

A competitive reaction exists between bovine serum albumin (BSA) and neomycin (NM) when ponceau S (PS) is chosen as fluorescent probe. This reaction was studied by fluorescence spectroscopy and UV–vis absorption spectroscopy. The static fluorescence quenching process between BSA and PS was confirmed and the binding constant, the number of binding sites and type of interaction forces between BSA and PS were obtained. It was observed that when NM was added into BSA–PS system, the relative fluorescence intensity of BSA was recovered gradually with increase in concentration of NM, which shows that there existed competitive reaction between BSA and NM. According to competitive reaction mechanism, the equilibrium concentration of PS, the binding constant and the type of interaction forces between PS and NM were obtained.