Temperature and pH-responsive nanogels as intelligent drug delivery systems: A comprehensive review

With the advancement of technology and the evolution of modern healthcare systems, the focus is shifting from conventional drug delivery vehicles to novel, nanosized carriers. Nanogels are an example of such nanosized drug delivery systems that have been researched at length. They can be designed to be sensitive to a multitude of physical and chemical stimuli and this endows them with the capability to deliver the drugs they carry in a site-specific manner. These intelligent drug delivery systems are biocompatible and capable of loading copious quantities of the drug. pH is a major chemical property and temperature is a major physical property of a biological system. So nanogels responsive to either pH or temperature or a combination of both, possess immense biomedical potential. This review encompasses synthetic techniques and evaluation tests to confirm the responsiveness of single pH-responsive nanogels and thermoresponsive nanogels as well as dual pH/thermoresponsive nanogels. A closer look is also taken at their biomedical applications.