Rapid synthesis of amphiphilic europium complexes via ultrasonic treatment-assisted crosslinking reaction

Abstract

The fluorescent nanomaterials based on rare earth metal complexes have become one of the promising candidates for biomedical applications due to their unique optical properties. However, direct utilization of these rare earth complexes in biological systems is challengable for their poor water solubility. In this work, an ultrasonic treatment-assisted crosslinking reaction was developed for the first time to synthesize the fluorescent amphiphilic copolymers (named as Eu (TTA)3phen-HCCP-PEG), in which the hydrophobic europium complexes (Eu (TTA)3phen-NH2) and hydrophilic polyethylene glycol were conjugated together using hexachlorocyclotriphosphazene (HCCP) as crosslinking agent. The reaction could be occurred uner room temperature, mild reaction conditions without using catalysts. Owing to the amphiphilicity of Eu (TTA)3phen-HCCP-PEG, fluorescent nanoparticles can be formed in aqueous solution. Thereinto, the uptake behavior of Eu (TTA)3phen-HCCP-PEG by cells and cell toxicity testing were also utilized to evaluate their potential applications in biomedical fields. Results demonstrated that these fluorescent nanoparticles are of small size, high water dispersibility and low toxicity. The above results implied that Eu (TTA)3phen-HCCP-PEG could be potentially for biological imaging and imaging-guided drug delivery etc.