Dual-Mode nanoprobes for heart tissue imaging

A new method that simultaneously alters multicolor upconversion luminescence (UCL) and improves overall UCL intensity, predominantly in red-emission bands, is presented here. Remarkedly enhanced temperature sensitivity at ultralow temperatures was also observed in Yb/Cu co-doped NaErF4 through transition metal Cu2+-doping. Varying the dopant (Cu2+) concentration in NaErF4:Yb effectively controlled the structure, allowing for blue, green, and red UCL output. Large enhancement across the entire UCL spectrum was observed for Cu2+-doped upconversion nanoparticles (UCNPs) compared to UCNPs not doped with Cu2+, resulting from non-radiative energy transfer between Cu2+ and Er3+. The rapid response of the NaErF4:Yb/Cu complex allowed for bioimaging of heart tissue within 1 h. Moreover, the relative sensitivity of UCNPs increased from 0.91% K-1 to 1.48% K-1 with metal Cu2+ doping at an ultralow temperature, which significantly impacts biomarker dependence on UCNPs.

Automated summary

This study presents a new method that simultaneously alters multicolor upconversion luminescence (UCL) and improves overall UCL intensity, with a particular focus on enhancing the red-emission bands. By doping with transition metal Cu2+, a remarkably enhanced temperature sensitivity at ultralow temperatures was observed in Yb/Cu co-doped NaErF4. Varying the Cu2+ concentration effectively controlled the structure, allowing for blue, green, and red UCL output. Cu2+-doped upconversion nanoparticles (UCNPs) showed a large enhancement across the entire UCL spectrum compared to UCNPs without Cu2+ doping, which resulted from non-radiative energy transfer between Cu2+ and Er3+.