pH-Responsive magnetic nanospheres for the reversibly selective capture and release of glycoproteins

Glycoproteins are related to many biological activities and diseases and their effective capture and release from a complex mixture is of great significance in proteomics and diagnostics. However, to separate and target glycoproteins with high efficiency and selectivity is difficult, due to the interference of nanomaterials and other proteins in complicated samples. In this study, Fe₃O₄/carboxymethylated chitosan/poly(3-acrylaminophenylboronic acid) (Fe₃O₄/CMCS/PAAPBA) nanospheres with enhanced properties are prepared by a facile and economical method, and possess excellent morphology, uniform size (∼300 nm), high saturation magnetization (59 emu g^-1), and high magnetic content (79%). Due to the introduction of PAAPBA, the Fe₃O₄/CMCS/PAAPBA nanospheres have been developed as a pH-responsive strategy to reversibly capture and release glycoproteins with high selectivity and recyclability in a pure protein, a model protein mixture and even a biological sample. Additionally, the Fe₃O₄/CMCS/PAAPBA nanospheres retained high separation efficiency (∼94%) in a pure protein system after being recycled five times, showing the great potential of the boronate functionalized, pH-stimuli-responsive, magnetic nanospheres in the biomedical field.