Nanohybrid for Photodynamic Therapy and Fluorescence Imaging Tracking without Therapy

Theranostic upconversion nanoparticles (UCNPs) are ideal candidates for personalized medicine. We present a smart, easy-to-prepare nanohybrid (NH) suitable for NIR-theragnosis and imaging tracking without triggering therapy simultaneously. The photophysical features of each component have been carefully selected in order to maximize the capabilities for theragnosis, in particular, the upconversion emission and the photosensitizer absorption. In addition, NH presents a fluorescent marker with one-photon absorption in the green and two-photon absorption cross-section at NIR wavelengths where the UCNP does not absorb, thus enabling innocuous tracking. Thus, the NH consists of NaYF4:Yb, Er, Tm (UCYbErTm) emitting in the UV, vis, and NIR; a broadband-absorbing natural porphyrin (PP) in the UV-to-NIR range but from 580 to 675 nm; and a 1,8-naphthalimide (NI) with two absorption bands (UV, VIS), and dual emission. In vitro assays demonstrate that UCYbErTm@PP/NI NH is noncytotoxic and extremely effective for NIR-induced cancer cell death. Moreover, this NH offers fluorescence tracking features without therapy due to the specific excitation of NI in the NIR and emission in the orange. This strategy opens up new alternatives for successful and noninvasive antitumoral theragnosis.