A Smart Europium–Ruthenium Complex as Anticancer Prodrug: Controllable Drug Release and Real-Time Monitoring under Different Light Excitations

A unique,
dual-function, photoactivatable anticancer prodrug, RuEuL, has been tailored that features a ruthenium­(II) complex
linked to a cyclen–europium chelate via a π-conjugated
bridge. Under irradiation at 488 nm, the dark-inactive prodrug undergoes
photodissociation, releasing the DNA-damaging ruthenium species. Under
evaluation-window irradiation (λirr = one-photon
350 nm or two-photon 700 nm), the drug delivery process can be quantitatively
monitored in real-time because of the long-lived red europium emission.
Linear relationships between released drug concentration and ESI-MS
or luminescence responses are established. Finally, the efficiency
of the new prodrug is demonstrated both in vitro RuEuL anticancer prodrug over some existing ones and open the way for
decisive improvements in multipurpose prodrugs.