Drug delivery demands a carrier that loads heavily, releases slowly, degrades safely and ideally reports its own location. Horcajada, Serre and an unusually large consortium showed that nanoscale iron(III) carboxylate MOFs of the MIL family could plausibly do all four, loading drugs like busulfan, azidothymidine triphosphate, doxorubicin and cidofovir at weight fractions conventional carriers could not touch, in some cases tens of percent of the particle mass.
The platform arguments were as important as the numbers. Iron and the dicarboxylate linkers chosen are comparatively benign, the particles degraded in simulated body fluid over days, releasing cargo progressively rather than in a burst, and the paramagnetic iron cores gave measurable MRI contrast in vivo in rats, making the carrier its own tracer. Flexible frameworks like MIL-53 even adapted their pores around awkward drug molecules, a soft-crystal trick rigid silica cannot perform.
Critical distance is required, and the authors largely kept it: this is a feasibility study, not a therapy. Toxicity was assessed acutely, not chronically; biodistribution, immune response and manufacturing reproducibility of nanoparticle batches all remained open, and a decade and a half later no MOF therapeutic has cleared clinical trials, a sobering calibration for the subfield this paper launched.
As a founding document, though, it is unusually complete, spanning synthesis, loading, release, degradation and imaging in one arc. Every 'MOFs in medicine' review since opens with it, and deservedly.