Water dispersive upconversion nanoparticles for intelligent drug delivery system

Abstract A novel near-infrared (NIR)-induced drug release system has been designed in this paper, based on upconversion nanoparticles and photosensitive amphiphilic polymers. Y-type photosensitive amphiphilic molecule, which had an azobenzene moiety in both hydrophobic chains, was synthesized. The resultant product, azobenzene-polyethylene glycol (AZO-PEG), was quite sensitive to ultraviolet (UV) and visible light. The prepared upconversion nanoparticles of NaYF 4 :Tm,Yb@NaYF 4 :Er,Yb (UCNP) were turned out that they could transfer NIR light into UV and blue light simultaneously. AZO-PEG and UCNP were mixed and self-assembled to an UCNP@AZO-PEG core-shell assembly. It was found that the assembly, UCNP@AZO-PEG, underwent isomerization upon irradiation with UV/visible light alternately as well as upconversion upon NIR light irradiation. As a model drug, doxorubicin (DOX) could be loaded into the assembly and released triggered by NIR light and different pH values, and the possible mechanism involved was discussed. The cell transfection results indicated that UCNP@AZO-PEG had good biocompatibility. Besides, DOX loaded in UCNP@AZO-PEG showed higher cell toxicity against HeLa cells.