We developed a humanized bifunctional antibody (mPEG×tumor marker),the anti-PEG end can be non-covalently modified to bind any PEGylated nano-druga contrast agent by one-step "formulation". The non-covalent binding solved the problems of chemical modification such as the masking of the antibody binding site, heterogeneity, drug instability. The other end of the bifunctional antibody can specifical