ALB and cancer: As shown in Figure 1d and Figure S2, the uptake of HSA‐TC‐Sulfo‐Cy5 exceeded that of HSA‐Sulfo‐Cy5 (2.2‐ to 5.4‐fold, calculated from the percentages of Sulfo‐Cy5‐positive cells) at different concentrations (200 and 500 nM) and time points (3 and 18 h) in both cell lines (MDA‐MB‐231 and HeLa), indicating that the conjugate prepared by the thiolation‐and‐conjugation approach may exhibit improved internalization by cancer cells, which is beneficial to tumor therapy.