ALB and neoplasm: As shown in Figure 1c, both HSA‐Sulfo‐Cy5 and HSA‐TC‐Sulfo‐Cy5 showed good accumulation in tumors, showing that the thiolation‐and‐conjugation method did not affect the tumor targeting ability of the protein of interest and indicating that the thiolation‐and‐conjugation may be a feasible approach to prepare protein conjugates.