(A) Aqueous anionic polyelectrolyte, poly(acrylic acid) [PAA, MW 450K], functionalized with the (B) bisphosphonate targeting moiety, alendronate [for high specificity to hydroxyapatite in bone], to yield (C) the aqueous, ligand-functionalized polymer at 40% side-chain functionalization (Figure S1), which is used for complementary, iterative adsorption to the polycationic component (poly-L-lysine, PLL) in the film on the NP substrate, schematically illustrated in (D).