Analytical Sciences

Characterization of Myoglobin Adsorption into Mesoporous Silica Pores by Differential Scanning Calorimetry

Akira YAMAGUCHI, Kazuhiro TAKI, Jun KIJIMA, Yurie EDANAMI, and Yuuta SHIBUYA

Institute of Quantum Beam Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan

Adsorption of protein molecules into the pores of a porous material is an important process for chromatographic separation of proteins and synthesis of nanoscale biocatalyst systems; however, there are barriers to developing a method for analyzing the process quantitatively. The purpose of this study is to examine the applicability of differential scanning calorimetry (DSC) for quantitative analysis of protein adsorption into silica mesopores. For this purpose myoglobin, a globular protein (diameter: 35.2 Å) was selected, and its adsorption onto mesoporous silica powders with uniform pore diameters (pore diameters: 39 and 64 Å) was measured by adsorption assay and DSC experiments. Our results confirmed that the adsorption of myoglobin into the silica mesopores induced significant changes in the positions and areas of freezing/melting peaks of the pore water. The decrease in heat of fusion of the pore water after myoglobin adsorption could be utilized to quantify the amount of myoglobin inside the silica mesopores. The advantages of DSC include its applicability to small wet mesoporous silica samples.

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