Controlling Enzymatic Polymerization from Surfaces with Switchable Bioaffinity

Abstract

The affinity of surfaces toward proteins is found to be a key parameter to govern the synthesis of polymer brushes by surface-initiated biocatalytic atom transfer radical polymerization (SI-bioATRP). While the "ATRPase" hemoglobin (Hb) stimulates only a relatively slow growth of protein repellent brushes, the synthesis of thermoresponsive grafts can be regulated by switching the polymer's attraction toward proteins across its lower critical solution temperature (LCST). Poly(N-isopropylacrylamide) (PNIPAM) brushes are synthesized in discrete steps of thickness at temperatures above LCST, while the biocatalyst layer is refreshed at T< LCST. Multistep surface-initiated biocatalytic ATRP demonstrates a high degree of control, results in high chain end group fidelity and enables the synthesis of multiblock copolymer brushes under fully aqueous conditions. The activity of Hb can be further modulated by tuning the accessibility of the heme pocket within the protein. Hence, the multistep polymerization is accelerated at acid pH, where the enzyme undergoes a transition from its native to a molten globule conformation. The controlled synthesis of polymer brushes by multistep SI-bioATRP highlights how a biocatalytic synthesis of grafted polymer films can be precisely controlled through the modulation of the polymer's interfacial physicochemical properties, in particular of the affinity of the surface toward proteins. This is not only of importance to gain a predictive understanding of surface-confined enzymatic polymerizations, but also represents a new way to translate bioadhesion into a controlled functionalization of materials.

Biodegradable Polyester Synthesis in Renewed Aqueous Polycondensation Media: The Core of the New Greener Polymer-5B Technology

“…More recently, aldol reactions were performed using Rhizopus arrhizus lipase [43]. Additionally, aqueous miniemulsions have been reported as environmentally benign enzymatic reaction media for polymerization [37,44]. In these polymerization media, there is no need to dry reagents before the polymerization, the water produced in dehydrative polyesterification is expelled to the continuous (aqueous) phase, and the biocatalyst stability is improved in comparison to an organic solvent.…”

Development of Environmentally Friendly Atom Transfer Radical Polymerization

“…The presence of GOx improved the fouling resistance of the polymer materials. Bruns et al found that the enzyme mediated surface-initiated biocatalytic atom transfer radical polymerization (SI-bioATRP) could be used to prepare PNIPAAm brushes [ 147 ]. This method provided a new way for the translation of bioadhesion into a controlled functionalization of materials.…”

Chlorophyll derivatives as catalysts and comonomers for atom transfer radical polymerizations

“…7,[16][17][18] We found that horseradish peroxidase (HRP) catalyzed the polymerization of N-isopropylacrylamide (NIPAAm) under activator regenerated by electron transfer (ARGET) ATRP conditions 16 whereas di Lena and coworkers showed that laccase and catalase could initiate polymerizations of poly(ethylene glycol) methyl ether methacrylate (PEGMA). 17,18 Since then, our group and others have demonstrated that metal-containing enzymes such as HRP, [19][20][21][22] laccase, 19,23 hemoglobin, [24][25][26][27] and catalase 19,28 can act as ATRP catalysts with distinct advantages, such as the ability to control the polymerizations of difficult monomers, which traditional ATRP conditions fail, 23 to confine polymerizations into nanoreactors, 20,21 to prepare biosensors, 26,27 and to tune surface-initiated polymerizations by the protein affinity of surfaces. 25 Metalloenzymes can be deduced to their cofactors, which also have been shown to catalyze ATRP.…”

“…17,18 Since then, our group and others have demonstrated that metal-containing enzymes such as HRP, [19][20][21][22] laccase, 19,23 hemoglobin, [24][25][26][27] and catalase 19,28 can act as ATRP catalysts with distinct advantages, such as the ability to control the polymerizations of difficult monomers, which traditional ATRP conditions fail, 23 to confine polymerizations into nanoreactors, 20,21 to prepare biosensors, 26,27 and to tune surface-initiated polymerizations by the protein affinity of surfaces. 25 Metalloenzymes can be deduced to their cofactors, which also have been shown to catalyze ATRP. [28][29][30][31][32][33][34] For example, Matyjaszewski and coworkers reported RDRP of methacrylates in aqueous solutions mediated by synthetic analogs of hemin and mesohemin, which were modified with 2-methoxy poly(ethylene glycol) (MPEG).…”