Visualization of real-time degradation of pH-responsive polyglycerol nanogels via atomic force microscopy

Polyglycerol nanogels (nPG) have a huge impact in biomedical applications as drug deliverer due to their high biocompability. For such nPG nanogels, particle degradation is widely used as drug delivery method. The knowledge of this degradation process is limited up to date. In this communication, a real time visualization of such a degradation process is presented for pH-responsive nPG nanogels via atomic force microscopy (AFM) under ambient and in liquid conditions. The particle height plays a major role in the degradation process and decays exponentially in the beginning of this process. The particle width increases during the process indicating a "decross-linking" step of the particles into their starting monomers. Measurements under ambient conditions confirm this assumption and provide further insight in the "decross-linking" step of the nanogels into individual dendritic particles. The present work gives a detailed insight in the particle degradation process, which is essential for further progress for the development of new drug delivery systems.