This thesis focuses the attention on the interaction forces between negatively charged carboxyl and sulfate latex particles with adsorbed on them respectively different generations of cationic poly(amido amine) PAMAM dendrimers and Linear (Polyethylene imine) (LPEI) having two different molecular masses. Those systems were investigated through the colloidal probe technique based on atomic force microscopy (AFM). Tuning the dendrimers/polyelectrolytes dose adsorbed, the interaction forces are observed to switch from repulsive into attractive and back to repulsive again in the both cases. Close to the IEP, the surface of the whole particle is totally neutralized by the adsorbtion of the dendrimers/polyelectrolytes. In the case of dendrimers, this situation is described by the sum of two attractive forces: a long range van der Waals interaction and short range non-DLVO forces given by patch charge interactions. In the case of LPEI the attractive forces are described in term of the pure DLVO theory.