Figure 4.

Release of SN38 and OxPt from OxPt/SN38. a) Proposed SN38 release via acid‐catalyzed hydrolysis and esterase‐mediated cleavage. Percentages of Chol‐SN38 and released products from OxPt/SN38 at b) pH = 4.7 in PBS and c) pH = 7.4 PBS with 10 unit mL⁻¹ esterase throughout 72 h at 37 °C. d) Percentages of SN38 released from OxPt/SN38 particle when incubated in PBS at pH = 4.7 or pH = 7.4 throughout 72 h at 37 °C. e) Release of OxPt from OxPt/SN38 via hydrolysis and reduction by ascorbate. f) Total Pt and OxPt release profiles from OxPt/SN38 particles when incubated in PBS with pH = 4.7 and 5 mm ascorbate at 37 °C. g) Time‐dependent Pt release from OxPt/SN38 particle when incubated in PBS at pH = 4.7 or pH = 7.4 at 37 °C. The inset showed the TEM image of disintegrated OxPt/SN38 particles after incubation in PBS at pH = 4.7 and 37 °C for 5 h.