Self-assembly of particles: some thoughts and comments

Self-assembly can happen to particles at all length scales, including atomic, nano-, meso- and macro-particles. Although widely used in nanoresearch, many nano-structures reported in the literature are not self-assembled, posing some fundamental questions. This paper will briefly review this topic, answering the following questions: what is the current status in self-assembling nanoparticles? Why is it so difficult to produce self-assembled structures of nanoparticles? How can we effectively overcome the difficulty? The important role of controlling forces of various types in relation to different self-assembly techniques is discussed. Self-assembly is demonstrated as a complex problem that still needs intensive multi-scaled studies.