Selective extraction of low molecular weight proteins by mesoporous silica particles with modified internal and external surfaces

A new mesoporous silica material with modified external and internal surfaces (alkyl diol–vinyl-SiO2) was prepared and applied to selectively extract low molecular weight (LMW) proteins and peptides (less than 11 kDa) from biological samples. X-ray diffraction, N2 adsorption, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to characterize the alkyl diol–vinyl-SiO2. This material was used to extract LMW proteins (peptides) from standard proteins, a mixture of peptides, and crude human plasma. We compared the amounts of different proteins adsorbed by alkyl diol–vinyl-SiO2 and by vinyl-SiO2 (vinyl group on the internal surface of the mesoporous silica material). The desorption recovery of alkyl diol–vinyl-SiO2 by different eluents was also investigated by using a standard protein (insulin) as a model LMW protein. The material could efficiently extract LMW proteins and peptides from a mixture of standard proteins and crude human plasma with good extraction efficiency and desorption recovery. Furthermore, the alkyl diol–vinyl-SiO2 had much better extraction selectivity for LMW proteins and peptides than a commercial C18 solid phase extraction material.