pH-Sensitive Polymeric Micelles for Programmable Drug and Gene Delivery

Polymeric micelles (PMs) belong to supramolecular core-shell-type assemblies. PMs are from amphiphilic block copolymers with several tens of nanometers in diameter. An important criterion verifying the effectiveness of micellar drug carriers is the ability to control the location and time over which drug release occurs. The pH variations in the body are particularly important in the development of micellar carriers for treating diseases such as cancer and inflammation. pH-sensitive PMs have emerged as a fascinating class of nano-scopic drug carriers that can be elegantly applied for programmed drug and gene delivery. In this review, we provide an analysis of recent literature reports on these pH-sensitive PMs. Different approaches that have been taken to develop pH-sensitive PMs are highlighted, including incorporating pH-sensitive building blocks such as poly(L-histidine) and poly(beta-amino ester), and acid degradable linkages such as hydrazones and acetals. The potential applications of pH-sensitive PMs within the biomedical field are also summarized.