Tailored Core-Shell Nanocarrier for Therapeutic Drug Delivery via Visible Light Activation

We present a novel drug delivery nanocarrier consisting of 300 nm-sized POT/Fe₃O₄/TRZ⁺TPB^- nanoparticles (NPs). The mechanism is based on the (photo)oxidation of poly(3-octylthiophene-2,5-diyl) (POT) (from POT⁰ to POT⁺), which facilitates the release of the positively charged drug trazodone (TRZ⁺) encapsulated in the NPs. The primary factor guiding the overall process is the maintenance of the electroneutrality condition in each NP. The incorporation of a Fe₃O₄ element enables the formation of an organic-inorganic heterojunction (Fe₃O₄/POT) in the core of the NP. This heterojunction permits us to utilize visible light to induce the POT photooxidation to trigger the release of TRZ⁺, unlike other platforms based on a more energetic illumination requirement. The developed nanocarrier allows for a controlled drug release, achieving doses of 3.5 µg mL^-1 of TRZ under 530 nm irradiation, 2.4 µg mL^-1 at 625 nm, and 1.6 µg mL^-1 at 470 nm within 1 h. The delivery is tested in undiluted blood serum, achieving an efficiency exceeding 90%. Overall, the integration of magnetic properties with a conductive polymer along with the adjustment of the band gap to enhance photooxidation performance in the visible range, constitute the conceptual innovation behind the controlled drug delivery system here presented, with TRZ as a model.