Supramolecular assembly has greatly promoted the development of drug/gene delivery system, due to the suitable micrometer or nanometer size, controllable structure and excellent biocompatibility. Recent studies have found that the topological structure plays a critical role in the drug/gene delivery process, which attracts great interest of researchers. In this paper, the main factors that regulate the morphology of micro-and nanoparticles are discussed, which mainly include composition of the copolymer, condition of self-assembly, external stimuli and polymerization-induced self-assembly. Then the effect of morphology on drug/gene delivery, challenges and prospects in this area are also discussed at the end of this review.

Contents
1 Introduction
2 Main methods of morphology regulation
2.1 Effect of the copolymer composition
2.2 Effect of self-assembly condition
2.3 Effect of external stimuli
2.4 Polymerization-induced self-assembly
3 The effect of morphology of drug/gene delivery system on blood circulation time and cell uptake
4 Conclusion