Facile Synthesis of ZnPc-Polydopamine Co-loaded Nanoparticles for Synergetic Photodynamic-Photothermal Therapy

Graphical A novel dopamine-modified epoxysilane was synthesized via a ring-opening reaction. Then, the photosensitizer ZnPc and photothermal-agent polydopamine were simultaneously introduced into nanoparticles by a facile encapsulation-reprecipitation method. The nanoparticles exhibited high photothermal conversion efficiency (η = 46.4%) and suitable photostability, apart from the capacity of 1 O 2 generation (Φ Δ =0.28). Based on the nanoparticles, improved therapeutic efficacy against tumor cells was achieved with synergetic treatment of PDT/PTT, even under hypoxia. A major obstacle to clinical photodynamic therapy (PDT) is tissue hypoxia in a solid tumor, which substantially reduces therapeutic efficacy by insufficient oxygen supply. To tackle this issue, herein, we reported a type of facilely prepared multifunctional nanoparticles (NPs) for combined treatment of PDT and photothermal therapy (PTT). A novel dopamine-modified epoxysilane (GSDA) was firstly synthesized from 3-glycidoxypropyl(trimethoxy) silane and dopamine via ring-opening reaction, which was subsequently incorporated into NPs along with zinc(II) phthalocyanine (ZnPc) via a reprecipitation-encapsulation method. Interestingly, polydopamine (PDA) was found to be automatically developed inside NPs by oxidative polymerization of dopamine monomers. Owing to strong-light-absorption PDA and ZnPc, the resultant biocompatible NPs exhibited high photothermal conversion efficiency (η=46.4%) and a decent singlet oxygen quantum yield (ΦΔ=0.28), respectively, under the irradiation of 808 nm and 660 nm light. Synergetic treatment was then performed on tumor cells using the multifunctional NPs, i. e., PDT followed by PTT, and enhanced phototherapeutic efficacy was achieved, particularly in the case of hypoxia. This work demonstrates that (i) the newly-synthesized GSDA might function as a bi-functional coupling agent for silica and PDA coating, and (ii) the simply-prepared NPs are very promising for synergetic PDT/PTT of solid tumors.