pH and redox dual responsive nanoparticle for nuclear targeted drug delivery.

To mimic the clinic dosing pattern, initially administering high loading dose and then low maintenance dose, we designed a novel poly(2-(pyridin-2-yldisulfanyl)ethyl acrylate) (PDS) based nanoparticle delivery system. Side chain functional PDS was synthesized by free radical polymerization. Polyethylene glycol and cyclo(Arg-Gly-Asp-d-Phe-Cys) (cRGD) peptide was conjugated to PDS through thiol-disulfide exchange reaction to achieve RPDSG polymer. RPDSG/DOX, RPDSG nanoparticle loaded with doxorubicin, was fabricated by cosolvent dialysis method. The size of the nanoparticles was 50.13 ± 0.5 nm in PBS. The RPDSG/DOX nanoparticle is stable in physiological condition while quickly releasing doxorubicin with the trigger of acidic pH and redox potential. Furthermore, it shows a two-phase release kinetics, providing both loading dose and maintenance dose for cancer therapy. The conjugation of RGD peptide enhanced the cellular uptake and nuclear localization of the RPDSG/DOX nanoparticles. RPDSG/DOX exhibits IC(50) close to that of free doxorubicin for HCT-116 colon cancer cells. Due to the synergetic effect of RGD targeting effect and its two-phase release kinetics, RPDSG/DOX nanoparticles display significantly higher anticancer efficacy than that of free DOX at concentrations higher than 5 μM. These results suggest that RPDSG/DOX could be a promising nanotherapeutic for tumor-targeted chemotherapy.