A ＂turn-off＂ luminescence resonance energy transfer aptamer sensor based on near-infrared upconverting NaYF4：Yb3＋, Tm3＋ nanoparticles as donors and gold nanorods as acceptors

Near-infrared upconverting NaYF4：Yb3＋, Tm3＋ nanophosphors modified with poly（acrylic acid） were prepared and characterized by transmission electron microscopy and luminescence spectroscopy. Based on the observed overlap between the emission spectrum of the NaYF4：Yb3＋, Tm3＋ nanophosphors and the absorption spectrum of the gold nanorods, we believe that a new “turn-off” luminescence resonance energy transfer aptamer sensor was constructed for sensing thrombin in near-infrared region.