Preparation of antibody-modified lipid (DSPE-PEG (2k)-Ab)

We dissolved 3-(N-succinimidyloxyglutaryl) aminopropyl, polyethyleneglycol 2000-carbamoyl distearoyl-phosphoethanolamine (DSPE-PEG (2k)-NHS, SUNBRIGHT DSPE-020GS; NOF Corporation, Tokyo, Japan) (0.123 mg) in chloroform. The lipid solution was evaporated to make a lipid film in a glass tube by chloroform removal. Then, the antibody solution (0.125 mg/mL, 0.56 mL) in PBS (pH 7.4) was added to the lipid film. The lipid film was rehydrated with antibody solution to conjugate the antibody to DSPE-PEG (2k)-NHS. The sample was incubated at 60°C for 5 min, and then at room temperature for 1 h to obtain the antibody-conjugated PEG-lipid (DSPE-PEG (2k)-Ab).