pH-responsive synthetic polymers for drug delivery applications

It is increasingly apparent that polymer-drug conjugates are a promising delivery platform. Introducing a pH-dependent linker between drug and polymer is expected to trigger the release of bioactive agents from conjugates in specific tissue locations, either in tumor tissues with mildly acidic extracellular matrixes or in cells with acidic endosomes and lysosomes after internalization. These pH-responsive polymer-drug conjugates can deliver and activate drug molecules while reducing their systemic side effects, making them an emerging method of drug delivery. This book chapter covers recent advances in pH-responsive polymer-drug conjugates, presenting their chemistry, synthesis, and characterization technology while attempting to clarify their mechanism of action. As part of this chapter, we will examine some pH-responsive polymeric drug delivery systems, along with their pros and cons and possible improvements. Our work focuses mainly on the pH-labile groups imide, ester, hydrazone, and imine, and the use of synthetic polymers like poly(methyl methacrylate) and polynorbornene.