In recent years considerable interest has developed in the exploitation of nanoparticulate drug delivery systems for a number of potential therapeutic applications. This has led colloid scientists to develop a variety of methods of biomedical surface engineering to tailor nanoparticles for particular delivery routes. However, in order to test the efficacy of such delivery avenues, an in vivo model is often required. Here we show how surface plasmon resonance (SPR) can be used to monitor specific interactions between colloidal particles and model surfaces where the colloid interface has been modified to minimize biointeractions or to promote selective interactions. Such procedures suggest that SPR may be used as an initial screening tool to ascertain the performance of such therapeutic systems in vitro before the need for in vivo experimentation.