Fig. 2. TTA-DFP-nCOF/insulin presents a glucose controlled release mode with delayed release and pH sensitivity. (a) In vitro accumulated insulin-release from the TTA-DFP-nCOF/insulin-FITC at 37 °C in PBS (10 mM) and pH 2.0 (black), or pH 7.4 in several glucose concentrations ([glucose] = 0 (red), 1 (green), 3 (pink) and 5 (blue) mg mL⁻¹). (b) Pulsatile release profile of TTA-DFP-nCOF/insulin-FITC at 37 °C as a function of glucose concentration ([glucose] = 1 versus 5 mg mL⁻¹). Error bars indicate ±S.D. of triplicate experiments.