A tosyl-activated magnetic bead cellulose as solid support for sensitive protein detection

• New magnetic bead cellulose was developed.
• The particles were functionalized with tosyl groups.
• The particles were used in proximity ligation assay (PLA) to detect vascular endothelial growth factor in femtomolar concentration range.
• The performance of particles was similar or even better compared to commercial magnetic beads.

Magnetic bead cellulose (MBC) was prepared using sol–gel transition of viscose in the presence of maghemite (γ-Fe2O3) nanoparticles. The MBC particles were then activated with p-toluenesulfonyl chloride to yield tosyl-activated magnetic bead cellulose (MBC-Ts). The microspheres were characterized by light and electron microscopy, elemental analysis and atomic absorption spectroscopy to determine morphology, size, polydispersity and content of iron and tosyl groups. The functionality of the MBC-Ts microspheres was demonstrated using proximity ligation assay (PLA) to detect vascular endothelial growth factor in femtomolar concentration range. The MBC-Ts microspheres performed equally well as commercially available microparticles that are routinely used as solid support in solid phase PLA.