Symmetrically and asymmetrically branched homopolymers are modified at the surface level with functional groups that enable forming aggregates with water insoluble or poorly water soluble pharmaceutically active agents (PAA). The aggregates formed are specifically induced by interaction of PAA and homopolymer and are different from aggregates that are formed by the polymer alone in the absence of the PAA or by the PAA alone in the absence of the polymer. Such aggregates can be used to improve drug solubility, stability, delivery and efficacy.