The development of functional polymeric nanoparticles is essential for breakthroughs in nanomedicine. Using well known polymerization techniques like the reversible addition-fragmentation chain transfer (RAFT) polymerization, it is possible to produce polymers with tailored properties for specific applications. In addition, postmodifications are used to further label the polymers to address specific targets. By tuning the polymer characteristics and subsequently applying optimized formulations for the procedure of nanoparticles, tailored nanoparticles with varying release properties, degradation behavior, targeting groups and size distributions can be developed. For the preparation of polymeric nanoparticles, nanoprecipitation is a good choice since it is a facile, mild, and low energy input process. The following investigations by using dynamic light scattering (DLS), analytical ultracentrifuge (AUC) and various microscopic techniques (SEM and TEM) allow a detailed characterization of the particles. Selected examples in the field of gene- and drug delivery vehicles will be presented, e.g. dual pH-value and redox responsive nanoparticles and polymersomes based on a methacrylate copolymer library [1,2,3]. The functionalization of the polymers with Raman active targeting structures enables the label-free visualization of cell uptake processes .