Fig. 2

a Absorbance of core, core@multishell, and UC-PMA NPs in chloroform and water. b Overlay of the Rose Bengal and Chlorin e6 absorbance and UC-PMA emission in water. c Summary of the PSs attached per UCNP. d DLS and LDA values of the different ligands’ combinations attached to the UCNPs; each bar is labeled with the corresponding polydispersity index (PDI). e Hydrodynamic diameter values (number-weighted) overtime in different media (water, blue; supplemented ALF, green; supplemented DMEM, orange) of UC-PMA (white dots) and UC-PMA-RB,Ce6 (black dots) (raw data showed in Additional file 1: Table S9)