Polyamidoamine (PAMAM) dendrimers have been synthesized by divergent with ethylenediamine as core. The interaction between PAMAM including amine-terminated generation 4.0 (G4.0)、generation 3.0 (G3.0) PAMAM and ester-terminated generation 3.5 (G3.5) PAMAM dendrimers and bovine serum albumin (BSA) under physiological condition was studied by fluorescence spectroscopy. The results showed that the fluorescence intensity of BSA decreased with the addition of different PAMAM dendrimers, the quenching extent strongly depends on the type and amounts of their surface groups. The quenching mechanism was static quenching mechanism. The quenching constants of G4.0 PAMAM, G3.5 PAMAM, G3.0 PAMAM with BSA were 2.73, 1.69, 1.55 L•mmol^－1, respectively. The influence of pH and ionic strength on the interactions was also investigated. Furthermore, synchronous fluorescence, ultraviolet-visible spectra analysis (UV), and red edge excitation shift (REES) showed that PAMAM dendrimers could change the conformation of BSA.

Key words: PAMAM dendrimers, bovine serum albumin, fluorescence quenching, synchronous fluorescence, red edge excitation shift