Protoporphyrin 9 ppix

Gold nanoclusters were prepared by reduction of tetrachloroauric acid in the presence of stabilizing ligands (see Supplementary Information). Protoporphyrin IX (PpIX) and Doxorubicin (DOX) were purchased from Frontier Scientific (Logan, UT, USA) and Sigma Aldrich, Chemical Co. (St. Louis, MO, USA), respectively. The protocols for conjugation to the nanoclusters and preparation of the corresponding linkers are described in the Supplementary Materials. Stock solutions were prepared in dimethyl sulfoxide (DMSO) and stored at 4 °C until use. Before incubation, stock solutions were allowed to equilibrate with room temperature for 30 min and were subsequently sonicated for 15 min to ensure complete dispersion of the nanoconjugates. Table 1 compiles information about gold and drug concentration in stock solutions.
After sonication, stock solutions were diluted in culture medium to the desired concentration (2.3 µM and 1.4 µM for PpIX and DOX, respectively). Unsubstituted AuNCs were used to assess the intrinsic toxicity of these nanoparticles.

L-〈-Distearoyl-phosphatidylcholine (DSPC), L-〈-Dioleoyl-phosphatidylserine (DOPS), and cholesterol (CHOL) were purchased from Avanti Polar Lipids (Birmingham, AL, USA). Irinotecan (CPT11), purchased from Afine Chemicals Limited (Hangzhou, China), was pure with a minimum grade of 99%. Protoporphyrin IX (PpIX), purchased from Frontier Scientific (Logan, UT, USA), had a minimum purity of 99% and was used as received. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) was purchased from Sigma Aldrich (Saint Louis, MO, USA). All other chemicals were commercially available reagents of at least analytical grade. Milli-Q water (Millipore Bedford, Massachusetts system, resistivity of 18 MΩ cm) was used.