Designing polyacrylic acid capped luminescent rare earth core–shell nanoparticles for simultaneous Cu(II) and temperature sensing

Cu 2+ is an essential trace element for humans and animals, and the precise detection of Cu 2+ can help diagnose many diseases. However, the current Cu 2+ detection technology still needs to be improved in terms of the biocompatibility of the material, the penetration of the excitation source, and the detection limit. In this paper, the polyacrylic acid (PAA) capped NaYF 4 :Yb 3+ /Er 3+ @NaYF 4 core–shell nanoparticles (NPs) with a particle size of about 22.5 nm is proposed. Under the excitation of 980 nm with strong penetration, the Cu 2+ concentration can be detected by the emission intensity of NPs at 520 nm, and the detection limit is 0.018 μM. In addition, this material can also perform temperature detection within 296–373 K with a relative sensitivity of 1.23 % K −1 . Therefore, this NPs is a promising multifunctional material that can detect temperature and Cu 2+ concentration.