pH Responsive in Vitro Cargo Release of PEG Coated MSNs Is Governed by Buffer Composition

The effect of different buffers on in vitro release of PEG coated mesoporous silica nanoparticles is discussed in this work. We prepared Rhodamine loaded and PEG coated mesoporous silica nanoparticles (PEG coated RhB@MSNs) of ~ 650 nm size and studied their release behaviour for 5 hours in various buffer solutions (both Na+ and K+ versions) prepared by standard procedure. We observed that Rhodamine release was highest in the citrate buffer. A comparison of different buffer effects on the in vitro release reveals that it is crucial to choose the right buffer for determining the loaded cargo release in each pH zone (acidic, neutral and basic). Clearly, choosing the wrong combination of buffers for different pH zones would result in completely different interpretation of the release behaviour.