Tunable multi-responsive nano-gated mesoporous silica nanoparticles as drug carriers

Tunable multi-responsive mesoporous silica nanoparticles were prepared by post-condensation/surface modification of MCM-41 nanoparticles. Surface grafting of a poly(N,N-dimethylaminoethyl methacrylate)-based polymer containing disulfide bonds was achieved by a click reaction. Chemical modification, morphological characteristics, and textural properties of the nanoparticles were studied using multiple characterization techniques such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, small-angle X-ray scattering, and nitrogen adsorption/desorption behavior. The nanoparticles retained the meso-structural integrity of MCM41 and particle size < 100 nm after grafting with the polymer. The pH and redox-responsive behavior of the nanoparticles were also studied. The nanoparticles possess excellent drug-loading capacity owing to their large surface area and 'closed gate' mechanism of the grafted polymer chains. The release profile of doxorubicin at two different pH (7.4 and 5.5) and in the presence of dithiothreitol showed a dual response behavior. The nano drug carrier device exhibited efficient intracellular uptake in cancer cells with suitable cytotoxicity and pharmacokinetic behavior, and may therefore be considered a good candidate for cancer therapy.