Page - (000359) - in Biomedical Chemistry: Current Trends and Developments

manipulation of the nanopore openings, with noncytotoxic solid supports for nanovalve-controlled drug delivery (Fig. 3.5.4) (Coti, 2009; Tarn, 2013; Xia, 2009). Figure 3.5.4: Schematic of a multifunctional mesoporous silica nanoparticle showing a core/shell design, surface modifications, and multiple types of cargos. Reprinted with permission from (Tarn, 2013). It is also known that MSNs are endocytosed by cells in an energy- dependent manner and colocalize to the lysosomes (Yanes, 2012). Thus, many researchers have reported pH-responsive MSNs modified with different kinds of gatekeepers. The activated release of anti-cancer drugs from mesoporous materials due to a pH change in the environment has mainly been achieved by using polyelectrolytes, supramolecular nanovalves, pH-sensitive linkers, and acid-decomposable inorganic materials (Yang, 2014; Zhang, 2014b). In a study reported by Meng, (Meng, 2010), a nanovalve-based delivery system was designed to meet the pH features of the acidic compartments of lysosomal organelles. The nanosystem had the ability to have the nanovalves closed at physiologic pH by non-covalent interactions, but open in response to changes in pH acidic conditions inside endosomal compartments by dissociation at pH 6 or lower after cellular uptake. The principle used here was based on