Deep eutectic solvents-based polymer monolith incorporated with titanium dioxide nanotubes for specific recognition...

An organic-inorganic hybrid monolith incorporated with titanium dioxide nanotubes (TNTs) and hydrophilic deep eutectic solvents (DESs) was prepared and evaluated by the isolation of proteins using solid phase microextraction. A typical polymerization system was composed of choline chloride/methacrylic acid (ChCl/MAA, DESs monomer), glycidyl methacrylate (GMA), as well as ethylene glycol dimethacrylate (EDMA) in the presence of TNTs. Then the epoxy groups on the surface of the resulting monolith were modified with amino groups. The synergistic effect of TNTs and DESs monomer to improve the enrichment performance of the sorbent significantly was demonstrated. Compared with the corresponding TNTs/DESs-free monolith, the recoveries of BSA and OVA were increased to 98.6% and 92.7% (RSDs < 2.0%), with an improvement of more than 60.0%. With a correlation coefficient of determination (R²) higher than 0.9995, the enrichment factors (EFs) were 21.9-28.3-fold. In addition, the resulting monolith was further applied to specifically capture proteins from rat liver according to their pI value, followed by HPLC-MS/MS analysis. The results indicated that the developed monolith was an effective material to isolate protein species of interest according to the pI value of target proteins.