Characterization methods. The morphology of bulk BN powder, BNNS-Arg, and BNNS-Arg@Lac was characterized by scanning electron microscope (SEM; Phenom Pharos G2 Desktop FEG-SEM, Thermo Fisher), transmission electron microscopy (TEM; FEI Tecnai T12, Tecnai), and high-resolution transmission electron microscopy (HRTEM; Talos F200C G2, Thermo Fisher). For SEM samples, all materials were dried and sputter-coated with Pt. TEM and HRTEM samples were resuspended in ethanol and dried on Lacey carbon support. The elements on the material surfaces were detected by SEM equipped with an energy dispersive X-ray detector (EDS) (Phenom Pharos G2 Desktop FEG-SEM, Thermo Fisher). The detailed structures were studied by X-ray diffraction (XRD; D8 Discover Powder X-ray Diffractometer; Bruker),