A facile and general approach for the preparation of boronic acid-functionalized magnetic nanoparticles for the selective enrichment of glycoproteins

Abstract

Biomedical applications and biomarkers for early clinical diagnostics and the treatment of diseases demand efficient and selective enrichment platforms for glycoproteins. Thus, we herein report a facile and general approach for the preparation of boronic acid-functionalized magnetic nanoparticles for the selective enrichment of glycoproteins. More specifically, Fe₃O₄ magnetic nanoparticles were initially prepared via a solvothermal reaction, and core–shell-structured Fe₃O₄@SiO₂ nanoparticles were obtained according to a sol–gel process. Subsequently, the Fe₃O₄@SiO₂ surfaces were modified using 4-formylphenylboronic acid to allow the formation of strong yet reversible covalent bonds between boronic acid (BA) and the cis-1,2-diol groups of glycoproteins. The morphology and structure of the Fe₃O₄, Fe₃O₄@SiO₂, and Fe₃O₄@SiO₂-BA nanoparticles were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometry, thereby confirming their successful preparation. The obtained BA-modified Fe₃O₄@SiO₂ magnetic nanoparticles were applied in the attempted enrichment of two glycoproteins (ovalbumin (OVA) and transferrin (TRF)) and two non-glycoproteins (bovine serum albumin (BSA) and cytochrome c (Cyt C)). The results confirmed a significant difference in affinity between glycoproteins and non-glycoproteins. In addition, the recognition capability of the Fe₃O₄@SiO₂-BA nanoparticles was demonstrated by the selective enrichment of glycoproteins from a complex system containing both glycoproteins (i.e., TRF) and non-glycoproteins (i.e., Cyt C).