The present invention generally relates to polymers and macromolecules, inparticular, to polymers useful in particlessuch as nanoparticles. One aspect of the invention is directed to a method ofdeveloping nanoparticles with desired properties. Inone set of embodiments, the method includes producing libraries ofnanoparticles having highly controlled properties, which can beformed by mixing together two or more macromolecules in different ratios. Oneor more of the macromolecules may be a polymericconjugate of a moiety to a biocompatible polymer. In some cases, thenanoparticle may contain a drug. Other aspects of the inventionare directed to methods using nanoparticle libraries.
