Polymeric hollow micro and nanospheres for biotechnological applications: A focused review

The rapid advancement of nanotechnology in the last ten years opened in medicine a real perspective of a significant breakthrough in the ability of therapeutics and imaging contrast agents to reach exactly the desired targets, with marginal or no collateral damages. Nanotechnologies based on the self-assembly of molecules resulting in nano-sized complexes play a key role in this advancement. In fact, molecular assemblies promise a tremendous potential for developing new diagnostic and therapeutic tools, as genuine 'nano-devices', able to interact with biological systems at molecular levels and with a high degree of specificity. However, the strong expectations raised by this approach, despite the great effort in terms of research and investments, have been since now frustrated by the rather low efficiency of the existing vectors. Nevertheless, taking into account the difficulty of the challenge, results are encouraging, and considering the importance of the stake, research in this field continues to be intensive. In this review we focus on a particular class of “micro/nano-devices”, i.e. hollow spheres, that appear to be particularly useful as “carriers” of active substances in biotechnological applications.