Interaction between PAMAM 4.5 dendrimer, cadmium and bovine serum albumin: a study using equilibrium dialysis, isothermal titration calorimetry, zeta-potential and fluorescence.

Binding of Cd(2+) by PAMAM 4.5 dendrimer was studied by equilibrium dialysis, isothermal titration calorimetry and zeta-potential measurement. The following binding parameters were obtained: n=23.8+/-9.5, K(b)=4.7+/-0.9x10(3) in water; and n=41.3+/-13.4, K(b)=2.1+/-0.8x10(3) in 0.15 mol/l phosphate-buffered saline. The location of the bound Cd(2+) is discussed. The interactions between bovine serum albumin, PAMAM 4.5 dendrimer and cadmium were analyzed using fluorescence and equilibrium dialysis. The competition between Cd(2+) binding to BSA and PAMAM 4.5 dendrimer was investigated. It is proposed that PAMAM 4.5 dendrimer could be successfully used for extracting Cd(2+) from aqueous solutions (environmental protection).