DPP-Cu2+ Complexes Gated Mesoporous Silica Nanoparticles For pH and Redox Dual Stimuli-Responsive Drug Delivery

A simple pH and redox dual stimuli-responsive diketopyrrolopyrrole (DPP)-Cu2+ complexes gated mesoporous silica nanoparticles (MSN) were prepared for precise drug delivery and controlled drug release.MSN was prepared by sol-gel method and then laminated. Carboxylic acid (CA)-Pyrrolo[3,4-c] pyrrole-1,4-dione, 2,5-dihydro-3,6-di-2-pyridinyl (PyDPP) was grafted onto the surface of amino-functionalized MSN (MSN-NH2) through a simple amide reaction and then complexed with Cu2+ to form gated molecules after doxorubicin (DOX) loading.Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Low-angle X-ray diffraction (XRD) showed that MSN with uniform particle size (100 nm) and porous structure was successfully prepared. The prepared MSN, MSN- NH2, and MSN-DPP were fully characterized by Zeta potential, Fourier transforms infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption- desorption. High DOX-loading capacity (18.22%) and encapsulation efficiency (89.16%) were achieved by optimizing the mass ratio of MSN to DOX. Release studies showed that the gated molecules of our designed DPP-Cu2+ complexes had a good blocking effect under physiological conditions (the cumulative release rate of drugs within 24 hours was only 4.18%) and responded well to the pH and redox glutathione (GSH) dual stimuli. In vitro cytotoxicity assay showed that MSN-DPP-Cu2+ had good biocompatibility in both Hep G2 cells and L02 cells (the relative cell viability of both cells within 48 hours was above 97%), and the MSN-DPP-Cu2+@DOX could be triggered for efficient drug release in Hep G2 cells.The MSN-DPP-Cu2+ described in this research may be a good delivery system for the controlled release of antitumor drugs and can provide a potential possibility for clinical application in the future.