ERBB2 and neoplasm: In the present study two types of theranostic nanocomplexes were obtained: UCNP coated with PMAO-PEG (I) for imaging tumors using passive delivery due to EPR-effect, and nanocomplexes based on UCNP and the target toxin DARPin-LoPE (II) for specific imaging and targeted therapeutic effects on HER2-positive tumor cells.