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. 2020 Jun 23;5(26):16220–16227. doi: 10.1021/acsomega.0c01890

Figure 1.

Figure 1

(a) HRTEM images of the PEG diacid-coated ultrasmall Eu–Gd nanoparticles. The corresponding circle shows the diameter of the nanoparticle, which is 2.1 nm (n = 71). (b) High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image and element mapping [Gd (green), Eu (red), O (blue)] of Eu–Gd NPs. (c) From DLS, the average size of the nanoparticle is 13.5 nm. (d) ζ-potential value is −25.1 mM for the Eu–Gd nanoparticles. (e) FT-IR absorption spectra of (I) free PEG diacid (black line), (II) PEG diacid-coated ultrasmall Eu–Gd nanoparticles (red line).