Abstract
Boronic acid based affinity materials are of great importance for effective enrichment of biomolecules containing a cis-diol structure, for example glycoproteins. In this work, we developed a new pH- and temperature-responsive boronate affinity material for effective separation of glycoproteins. A nanohybrid material composed of silica cores and flexible polymer brushes, denoted as Si@poly(NIPAm-co-GMA)@APBA, was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) in combination with Cu(i)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction. The size, morphology and composition of the obtained nanohybrid were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), elemental analysis and thermogravimetric analysis (TGA). The density of polymer brushes on the surface of silica nanoparticles was determined to be 0.7 molecules per nm2. The maximum binding capacities of the nanohybrid Si@poly(NIPAm-co-GMA)@APBA for ovalbumin (OVA) and horseradish peroxidase (HRP) were determined to be 87.6 mg g-1 and 22.8 mg g-1, respectively. Glycoprotein binding on the nanohybrid could be controlled by varying the pH of the binding buffer. By increasing the temperature from 20 °C to 35 °C, glycoprotein binding onto the nanohybrid was decreased. This new pH- and temperature-responsive nanohybrid will be useful for a number of biotechnological and biomedical applications, for example, for protein separation and drug delivery.
Highlights
Organic/inorganic hybrid materials have attracted ever increasing attention in recent years due to their unique structural characteristics and potential applications in bioseparation,[1] targeted drug/ gene delivery,[2,3] theranostics and more.[4]
The advantage of this synthetic design is that the intermediate particles, Si@poly(NIPAm-co-Glycidyl methacrylate (GMA)), can be used as a general reagent to synthesize different types of affinity adsorbents, depending on the types of the organic amines used to react with the epoxy groups
The intermediate polymer brushes, poly(NIPAm-co-GMA), were grafted from an amino-functionalized silica core via the surface-initiated atom transfer radical polymerization (SI-ATRP) process followed by post-functionalization with propargylamine, and conjugated to an azide-tagged fluorogenic boronic acid via click reaction under mild conditions
Summary
Organic/inorganic hybrid materials have attracted ever increasing attention in recent years due to their unique structural characteristics and potential applications in bioseparation,[1] targeted drug/ gene delivery,[2,3] theranostics and more.[4]. In order to introduce the azide-functionalized APBA into the polymer brushes, the Si@poly(NIPAm-co-GMA) particles were first reacted with propargylamine to produce multiple alkyne groups, which were used to conjugate the fluorogenic APBA through the CuAAC click reaction. To determine the molecular weight of the grafted polymer brushes, we first treated Si@poly(NIPAm-co-GMA) particles with HF to remove the inorganic core.
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