The influence of surface functions on the interactions between Poly(PhosphorHydrazone) PPH dendrimers and human monocytes is discussed on the basis of complementary biological and physicochemical studies on membrane models (monolayers and multi-lamellar vesicles). The studies were performed on both an active and non-toxic phosphonic acid capped dendrimer and a non-active but toxic carboxylic acid capped one. On the one hand, comparative studies of the behaviour of DPPC monolayers in the presence or absence of PPH dendrimers in the subphase showed differences in the phase transitions, highlighting interactions between both dendrimers and phospholipid monolayers, with a larger incidence for the carboxylic acid capped dendrimer (negative control), validating its cellular toxicity. On the other hand, comparative biological studies (activation of human monocytes and binding of fluorescent dendrimers on human monocytes) show the pre-eminence of phosphonic acid capped dendrimers towards specific binding and subsequent activation of human monocytes.