A rhodamine-based sensing probe excited by upconversion NaYF4:Yb3+/Er3+ nanoparticles: The realization of simple Cu(II) detection with high sensitivity and unique selectivity

In this paper, upconversion nanoparticles of β-NaYF4:Yb3+/Er3+ and a rodamine derivative of 2-amino-3′,6′-bis(ethylamino)-2′,7′-dimethyl-3′,9a′-dihydrospiro [isoindoline-1,9′-xanthen]-3-one (referred as Rd-NH2) were constructed and fully characterized. The energy transfer process between β-NaYF4:Yb3+/Er3+ and Rd-NH2 was also investigated. Data analysis suggests that the upconversion emission from β-NaYF4:Yb3+/Er3+ can efficiently excite Rd-NH2. Using this upconversion emission as an excitation source and Rd-NH2 as a sensing probe, their sensing behavior towards Cu2+ was investigated. It was found that β-NaYF4:Yb3+/Er3+:Rd-NH2 system showed linear response towards Cu2+ in the range of 2–14 μM. In addition, β-NaYF4:Yb3+/Er3+:Rd-NH2 system processed good selectivity towards Cu2+ and high chemostability, making β-NaYF4:Yb3+/Er3+:Rd-NH2 a promising sensing system towards Cu2+. - Highlights: ► Upconversion nanoparticles of β-NaYF4:Yb3+/Er3+ have been constructed. ► A rodamine derivative for Cu2+ sensing has been synthesized. ► An effective energy transfer between excitation source and sensor was achieved. ► β-NaYF4:Yb3+/Er3+:Rd-NH2 system showed linear response towards Cu2+. ► Good selectivity and high chemostability have been realized.