The use of reversible addition fragmentation chain transfer polymerization for drug delivery systems

Introduction: Reversible Addition Fragmentation Chain Transfer (RAFT) polymerisation is now an established tool for polymer chemists to create various polymer architectures with precise control over the molecular weight, and to install a variety of different moieties onto the polymer chain ends. Recently, there seems to be a trend of moving polymer science away from the traditional academic focussed research, to instead identifying real-world problems and how these can be solved with the aid of macromolecules. Areas covered: This article has two themes; the synthesis of polymers for polymer therapeutics; and the design of polymer carriers for the physical encapsulation of drugs and genes, which can either be micelles, gels or other core-shell particles. The first part summarizes the avenues polymer chemists have developed by using RAFT polymerization to attach active compounds (such as drugs or proteins) to polymer chains. The second part gives an overview of the possibilities of using polymer nanocarriers (such as micelles, other core-shell nanoparticles, hydrogels and cationic polymers) for drug delivery. Expert opinion: RAFT polymerisation seems to have endless possibilities in terms of macromolecular design, that is once the pitfalls of the process have been considered, which are based on the radical nature of the mechanism. Polymer chemists have explored many synthetic pathways in order to generate a myriad of structures, and to provide proof of concept for their ideas. However, considering the length of time it takes to get a polymer into a clinical trial, attention should be focussed on detailing the biological evaluation of these well-defined structures.