Dimethylimidazole

A balance was used to weigh out 162 mg of dimethylimidazole (Sigma), 73.32 mg of zinc nitrate hexahydrate (Sigma), and 1 mg of HMME (Di-Bai Chemical Technology Co., Ltd.). They were then totally dissolved in 15 mL of methanol, stirred at room temperature for 20 min, and then centrifuged for 5 min to obtain a pellet (H@ZIF-8). The precipitate was resuspended in ethanol. And then the F127 solution (5 mg/mL) and tH@ZIF-8 nanoparticles were mixed, stirred for 2 h, and centrifuged again to produce the precipitate (HF@ZIF-8). The precipitate was dissolve with water and mixed with the hemoglobin solution (1 mg/mL) and stirred overnight on ice. The free hemoglobin was further removed by centrifugation. The nanoparticles solution was oscillated on the shaker while introducing pure oxygen, which was repeated for 3 times until fine bubbles emerged from the liquid surface and centrifuge to generate HFH@ZIF-8.

dimethyl imidazole (99%, Analytical grade), zinc nitrite hexahydrate (99%, Analytical grade), zinc acetate tetrahydrate (99%, Analytical grade), cobalt nitrite hexahydrate (99%, Analytical grade), potassium hydroxide (85%, Analytical grade) and methanol (99.9%, anhydrous) were purchased from Sigma-Aldrich. Nafion^TM dispersion (5 wt.% in ethanol) was purchased from Ion Power. All chemicals were used without further purification. The deionized water (18 MΩ) was obtained from a Millipore System.