The interaction between PAMAM G3.5 dendrimer, Cd2+, dendrimer–Cd2+ complexes and human serum albumin

The interactions between PAMAM G3.5 dendrimer, Cd2+, a complex of “PAMAM G3.5 dendrimer-Cd2+” and human serum albumin were studied by equilibrium dialysis, fluorescence quenching, fluorescence anisotropy and zeta-potential. It was found that in water one molecule of PAMAM 3.5 dendrimer can bind 38 ± 9 cadmium ions with Kb = 1.3 ± 0.13 × 103. The calculated Stern–Volmer constants of albumin fluorescence quenching by Cd2+, G3.5 and the “PAMAM G3.5-Cd2+” complex were 2.2 ± 0.2, 1.6 ± 0.3 and 1.4 ± 0.1 (mmol/l)−1, respectively. The data from the fluorescence and zeta-potential studies show that the “PAMAM G3.5-Cd2+” complex interacted much less strongly with human serum albumin than the pure dendrimer or Cd2+.