Determination of Lysozyme in Egg White Using Molecularly Imprinted Polymer Coated Capillary by Capillary Electrophoresis

This work aims to develop a capillary based on molecularly imprinted polymer coating for the on-line preconcentration and selective determination of lysozyme in egg white, combining the template immobilization strategy, surface imprinting approach, and post-imprinting modification strategy by using capillary electrophoresis. First, the capillary was coated with polydopamine and then the 3-mercaptopropionic acid coating was formed through self-assembly for subsequent immobilization of template lysozyme. Afterward, the surface-imprinted polydopamine coating was fabricated by the self-polymerization of dopamine as a functional monomer and cross-linker. After that, partially hydrolyzed poly(2-methyl-2-oxazoline), which possesses the protein-resistant adsorption ability, was introduced to reduce the nonspecific adsorption of the polydopamine coating. Finally, lysozyme molecularly imprinted polymer coated capillaries were obtained after lysozyme was eluted. The created coating was characterized by electroosmotic flow mobility measurements, scanning electron microscope, static water contact angle, and attenuated total reflection Fourier-transform infrared spectrum. Lysozyme standard solutions (concentration from 0.5 to 10.0 ng/mL) were analyzed using the fabricated capillary, achieving the detection limit of 0.1 ng/mL. In addition, the accuracy, repeatability, reproducibility, and selectivity of the prepared capillary were investigated. The recovery values of lysozyme gained were from 96.0% to 98.7% for hen egg white samples using the developed capillary.