Synthesis and characterization of nanoparticles, consisting of a gadolinium paramagnetic core and a mesoporous silica shell, for controlled delivery of hydrophobic drugs

As a strategy to improve drug delivery systems, paramagnetic gadolinium nanoparticles consisting of a paramagnetic nucleus (Gd 2 (OH) 5 NO 3 ) and a mesoporous silica shell were prepared. The novelty of these nanoparticles is that the hydrophobic environment in the pores allows for facile immobilization of drugs that are not freely soluble in water. This was demonstrated by loading the pores of the nanoparticles with either the antibiotic chlortetracycline (ctcl) or the anticancer drug chlorambucil (cmbl). The structural and magnetic properties of the resulting drug-nanoparticle complexes were extensively characterized by various techniques which revealed that they were both paramagnetic and highly ordered, and had an excellent drug-loading capacity. Gradual release of both chlortetracycline and chlorambucil was demonstrated by studying their release profiles. The profiles for both GdSiO–ctcl and GdSiO–cmbl nanoparticles and their paramagnetic properties show that these species are appropriate candidates for controlled drug delivery, particularly in combination with MRI studies.