The development of pure nanodrugs (PNDs) has led to the possibility of delivering the anticancer agents without involving nanocarriers. On the path to its clinical application, the dispersion stability of PNDs must be improved. In the present study, we tried to improve the dispersion stability of ester-linked SN-38 dimer by surface modification with coordination complexes between tannic acid (TA) and metal ions. TA and Fe(III)complexes coated SN-38 dimer PNDs (TA-Fe/PNDs) showed superior colloidal stability as they did not show aggregation, comparing to non-coated PNDs. It was also found that the release of the active SN-38 moiety from TA-Fe/PNDs was faster than that from the aggregated PNDs, because of the larger surface area in contact with the enzyme of mouse serum to facilitate the drug release.