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-SiO(2)) was prepared and applied to selectively extract low molecular weight (LMW) proteins and peptides (less than 11 kDa) from biological samples. X-ray diffraction, N(2) adsorption, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to characterize the alkyl diol-vinyl-SiO(2). 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-SiO(2) and by vinyl-SiO(2) (vinyl group on the internal surface of the mesoporous silica material). The desorption recovery of alkyl diol-vinyl-SiO(2) 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-SiO(2) had much better extraction selectivity for LMW proteins and peptides than a commercial C(18) solid phase extraction material.