A novel nanotheranostic agent for dual-mode imaging-guided cancer therapy based on europium complexes-grafted-oxidative dopamine

Abstract A simple method is presented for the preparation of novel europium complexes-grafted-oxidative dopamine (ECOD) nanoparticles with uniform sizes (ca. 220 nm), as a high-performance nanotheranostic agent guided by X-ray computed tomography (CT) and photoluminescence (PL). Here, an oxidative dopamine precursor with a rough surface is first prepared by copper (II) ionic catalysis. Then, europium complexes are successfully grafted onto the oxidative dopamine precursor by surface-initiated atom transfer radical polymerization (ATRP). Interestingly, as the additional amount of europium (III) complexes increases, the roughening extent of the ECOD nanoparticles is increased, and the roughening surface expands to a porous network structure. This nanoagent with a rough surface exhibits not only excellent X-ray attenuation properties, but also prominent eminent near-infrared (NIR) absorbance and strong optical imaging efficiency. In addition, ECOD can provide an effective photothermal therapy (PTT) effect, and 39% photothermal conversion efficiency can be achieved. Furthermore, there is no widely detectable toxicity induced in vivo/vitro, and blood circulation can last for a long time in the presence of ECOD nanoparticles, leading to efficient accumulation at the tumor site by a persistently of enhanced permeability and retention (EPR) effect. With the combination of NIR laser irradiation (1.5 W/cm2) for 10 min at 808 nm, effective photothermal ablation of a tumor in vivo can be achieved. Thus, ECOD nanoparticles can be used for effective antitumor treatment and may further exhibit potential as a nanotheranostic agent for clinical diagnosis and treatment.