Magnetite nanoparticles as smart carriers to manipulate the cytotoxicity of anticancer drugs: magnetic control and pH-responsive release

We described the smart and targeted magnetic nanocarriers to control the delivery and release of anticancer drug doxorubicin (DOX) in vitro and demonstrated that they can exhibit much higher cytotoxicity to cancer cells than free DOX. The conjugation of targeted magnetite nanoparticles (similar to 14 nm in diameter) and DOX molecule via acid-labile imine bond endows the nanocarriers with three advanced features: magnetically controllable, specific targeting, and pH-responsive. The cell toxicity assays indicated the pH-sensitive magnetic nanocarriers (IC50 of 0.13 mu g mL(-1) to HeLa cells) have much higher anticancer activity than free DOX (IC50 of 1.16 mu g mL(-1) to HeLa cells). Moreover, the magnetically guided delivery of nanocarriers can further improve the drug efficacy (IC50 of similar to 0.087 mu g mL(-1) to HeLa cells). The arginine-glycine-aspartic acid (RGD)-modified magnetic nanocarriers recognized the specific cells effectively (IC50 of 0.93 mu g mL(-1) to U-87 MG cells) and showed the increased cytotoxicity to cancer cells under external magnetic fields. This intelligent (magnetically guided, molecular targeted, and pH-responsive) drug delivery system has the ability to improve the chemotherapeutic efficacy and reduce the side effects, which has a great potential to become a favorable strategy for delivery of drugs to the desired sites in patients.