Fig. 5From: Fabrication of NaYF4:Yb,Er Nanoprobes for Cell Imaging Directly by Using the Method of Hydrion Rivalry Aided by Ultrasonic a The curve of the zeta potentials of OA-free NaYF4:Yb,Er NPs at different pH values. b The FTIR spectra of the complexes of amine acid coupling with NaYF4:Yb,Er NPs. a new-NaYF4:Yb,Er, b–e new-NaYF4:Yb,Er coupled with glycine, threonine, glutamic acid, and lysine, respectivelyBack to article page