Dual-functional polymer-modified magnetic nanoparticles for isolation of lysozyme.

An artificial receptor approach for proteins capture and release was designed based on ionic-sensitive and thermo-sensitive functionalized polymers, which were modified onto the surface of magnetic nanoparticles. The dual-functional poly(styrene-sulfonate-N-isopropylacrylamide) (P(SS-NIPAm)) was synthesized via the free radical polymerization method and used as the artificial receptor with electrostatic, hydrophilic and hydrophobic properties. The affinity between the artificial receptor and lysozyme was investigated using high performance liquid chromatography. Arising from the strong and specific interactions between the negatively charged sulfonic acid groups of P(SS-NIPAm) and positively charged amino groups of the protein, the prepared artificial receptor exhibited outstanding affinity for lysozyme. Interestingly, due to the thermo-responsive and ionic strength-responsive features of the prepared P(SS-NIPAm), the capture and release process for lysozyme could be modulated by varying the environmental temperature and ionic strength. Further, the proposed artificial receptor based on P(SS-NIPAm) modification of magnetic nanoparticles surface was used for affinity capture of lysozyme in human serum with a recovery ranging from 89.9% to 100.4%, paving a new way for synthesis of artificial receptors and showing great potential for recognition of target protein in real bio-samples.