Multi-walled carbon nanotubes coated silica gel and its application to solid-phase extraction and preconcentration of protein species

A new sorbent for solid phase extraction/preconcentration of proteins was prepared by coating multi-walled carbon nanotubes on silica gel spheres (MVNTs/SiO2) using polyelectrolyte-assisted layer-by-layer (LBL) assembly technique. The adsorption behavior of cytochrome c onto the MWNTs/SiO2 spheres is in good agreement with the Langmuir adsorption model. The effects of pH, the concentration and composition of the eluent on the retention behavior of cytochrome c were investigated. A maximum sorption capacity for cytochrome c of 250 mg g(-1) was achieved. An enrichment factor of 30 was derived with a sample loading volume of 2.0 ml. The micro-column packed with the MWNTs/SiO2 sphere facilitates high throughput attributed to its decreased flow impedance, which results in a high efficiency of protein separation and preconcentration.