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

## TL;DR

A new light-activated nanocarrier delivers drugs using visible light, offering controlled release in blood serum with high efficiency.

## Contribution

The integration of magnetic properties and a conductive polymer enables visible light-triggered drug release with precise dosage control.

## Key findings

- The nanocarrier achieved 3.5 µg mL−1 TRZ release under 530 nm light within 1 hour.
- Drug delivery efficiency exceeded 90% in undiluted blood serum.
- Visible light activation outperforms other platforms requiring more energetic illumination.

## Abstract

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.

A core‐shell nanocarrier activated by visible light, composed of poly(3‐octylthiophene‐2,5‐diyl) (POT), iron oxide (II, III) (Fe3O4), polyvinyl alcohol (PVA), and trazodone tetraphenylborate (TRZ+ TPB−). During POT photooxidation (POT+), TRZ+ is liberated driven by the maintenance of particle's electroneutrality. The inorganic‐organic POT/Fe3O4 heterojunction facilitates accurate dosage under mild irradiation, demonstrating a novel conductive polymer‐based delivery platform. FPOT and FTRZ: fluorescence of POT and TRZ.