Construction of a Glutathione-Responsive and Silica-Based Nanocomposite for Controlled Release of Chelator Dimercaptosuccinic Acid.

Dimercaptosuccinic acid (DMSA) is an oral heavy metal chelator. Although DMSA is the most acceptable chelator in the urinary excretion of toxic elements from children and adults, its defects in plasma binding and the membrane permeability limit its interaction with intracellular elements and affect its efficacy in chelation therapy. Herein, a novel nanocomposite composed of mesoporous silica nanoparticles (MSNs), disulfide bond, and DMSA was synthesized and characterized with a scanning/transmission electron microscope, IR and Raman spectra, and TGA analysis. The in vitro interactions with glutathione (GSH) and cellular uptake assays showed that it was able to be stable in extracellular environments such as in blood, be internalized by cells, and release DMSA inside via GSH-triggered disulfide cleavage reaction. The in vitro adsorption assays showed that MSNs-SH as its intracellular metabolite had strong adsorbability for models of Hg2+ or Pb2+. The hemolysis and cell viability assays showed that it was compatible with blood and cells even at a concentration of 1000 μg·mL-1. All above could not only enable it to be a GSH-responsive drug delivery system (DDS) for DMSA delivery but also to be a solution for its defects and efficacy. Thus, introduction of intelligent DDS might open a new avenue for DMSA-based chelation therapy.