Abstract
A hybrid bifunctional core–shell nanostructure was synthesized for the first time via surface-initiated atom transfer radical polymerization (SI-ATRP) using myoglobin as a biocatalyst (ATRPase) in an aqueous solution. N-Isopropyl acrylamide (NIPA) and N-(3-aminopropyl)methacrylamide (APMA) were applied to graft flexible polymer brushes onto initiator-functionalized silica nanoparticles. Two different approaches were implemented to form the core–shell nanocomposite: (a) random copolymerization, Si@p(NIPA-co-APMA) and (b) sequential block copolymerization, Si@pNIPA-b-pAPMA. These nanocomposites can be used as versatile intermediates, thereby leading to different types of materials for targeted applications. In this work, a phenylboronic acid ligand was immobilized on the side chain of the grafted brushes during a series of postmodification reactions to create a boronate affinity adsorbent. The ability to selectively bind glycoproteins (ovalbumin and glycated hemoglobin) via boronic acid was assessed at two different temperatures (20 and 40 °C), where Si@pNIPA-b-APMABA (163 mg OVA/g of particle) displayed an approximately 1.5-fold higher capacity than Si@p(NIPA-co-APMA)BA (107 mg OVA/g of particle). In addition to selective binding to glycoproteins, the nanocomposites exhibited selective binding for myoglobin due to the molecular imprinting effect during the postmodification process, that is, 72 and 111 mg Mb/g for Si@p(NIPA-co-APMA)BA and Si@pNIPA-b-pAPMABA, respectively.
Highlights
Since the introduction of atom transfer radical polymerization (ATRP), this method has been utilized to form complex topologies using metal ions as catalysts.[1]
The concept of growing polymer brushes on a surface using metalloenzymatic radical polymerization was reported in the literature,[13,15−18] where catalase from bovine liver and laccase from Trametes versicolor were utilized as biocatalysts to graft poly(N-isopropyl acrylamide) polymer brushes from nanofiber surfaces.[15]
The effect of the introduction of amine groups followed by the initiator on the silica nanoparticles can be seen in the Fourier transform infrared (FTIR) spectra (Figure S1)
Summary
Since the introduction of atom transfer radical polymerization (ATRP), this method has been utilized to form complex topologies using metal ions as catalysts.[1]. Many recent studies have focused on reducing catalyst consumption to the ppm level, where external physical or chemical forces regenerate the active parts.[11,12] This approach makes the system more environmentally friendly and economical. Even with this improvement, the risk of having an inorganic catalyst present in the formed product makes this approach less interesting for many applications, such as biomedical purposes. The reaction mixture was removed from the ice bath and stirred at room temperature overnight. The particles were dried at room temperature under vacuum and denoted as Si@initiator
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