Study on the assembly of hemoglobin by nano mesoporous SBA-15 and catalytic activity

In this paper, SBA (Santa Barbara Amorphous)-15 molecular sieve was successfully prepared by hydrothermal method, the molecular sieve was used as a host to immobilize hemoglobin (Hb) guest material and (SBA-15)-Hb nano composite material was prepared. By optimizing the adsorption conditions of hemoglobin on SBA-15, the optimum adsorption conditions were obtained. In them, the optimum adsorbate Hb/adsorbent (SBA-15) is 2/25 and pH = 6.80. At this time, the maximum immobilization amount of Hb by SBA-15 is 78.48 mg/g. The best adsorption condition of Hb by CH₃-(SBA-15) is that the adsorbate (Hb)/adsorbent [CH₃-(SBA-15)] is 2/23, pH = 6.80. At this time, the maximum amount of hemoglobin on the CH₃-(SBA-15) is 74.59 mg/g. Through the powder X-ray diffraction, Fourier infrared spectrometry, UV-visible solid diffuse reflectance spectroscopy, luminescence spectrum, 77 K low temperature N₂ adsorption–desorption study it is shown that the hemoglobin has been successfully immobilized in the channels of the host material. Scanning electron microscopic results showed that the average diameter of the (SBA-15)-Hb was 346 ± 10 nm, the average diameter of the [CH₃-(SBA-15)]-Hb was 350 ± 10 nm. Process of the adsorption of Hb by SBA-15/CH₃-(SBA-15) was in accord with the quasi-two-order kinetic model. SBA-15/CH₃-(SBA-15) adsorption Hb process is an exothermic reaction, and belongs to a spontaneous reaction process. During the depsorption process of composite (SBA-15)-Hb/[CH₃-(SBA-15)]-Hb in 0.1 mol/L NaOH solution, at 9 h, equilibrium was reached and the desorptions rate is 80.00 and 73.04%, respectively. Experimental results of the reuse activity for (SBA-15)-Hb/[CH₃-(SBA-15)]-Hb showed that the repeated use time for material [CH₃-(SBA-15)]-Hb after methylation is higher than that of (SBA-15)-Hb, indicating that “leakage” of the enzyme was reduced in the host materials after the methylation of SBA-15. The luminescence spectra showed that the prepared composites have some luminescence properties.

Freundlich adsorption isotherms for the adsorption of hemoglobin by SBA-15