Amylose‐Coated Biohybrid Microgels by Phosphorylase‐Catalyzed Grafting‐From Polymerization

Abstract

Herein, the synthesis of amylose‐coated, temperature‐responsive poly(N‐vinylcaprolactam) (VCL)‐based copolymer microgels by enzyme‐catalyzed grafting‐from polymerization with phosphorylase b from rabbit muscle is reported. The phosphorylase is able to recognize the oligosaccharide maltoheptaose as primer and attach glucose units from the monomer glucose‐1‐phosphate to it, thereby forming amylose chains while releasing inorganic phosphate. Therefore, to enable the phosphorylase‐catalyzed grafting‐from polymerization of glucose‐1‐phosphate from the PVCL‐based microgels, the maltoheptaose primer is covalently attached to the microgel in the first synthesis step. This is realized by adding N‐(2‐aminoethyl)methacrylamide (AEMAA) as a comonomer to the PVCL microgel to integrate primary amino groups and subsequent coupling of maltoheptaonolactone. Both the PVCL/AEMAA microgel as well as the obtained microgel–maltoheptaose construct are characterized in detail by dynamic light scattering, electrophoretic mobility measurements, IR spectroscopy, and atomic force microscopy. From the microgel–maltoheptaose construct, the grafting‐from polymerization of glucose‐1‐phosphate is performed by the addition of phosphorylase b. Atomic force microscopy images clearly demonstrate the formation of an amylose shell around the microgels. The developed amylose‐coated microgels open up promising application possibilities, for example, as colloidal scavengers, since amylose helices can serve as host molecules for inclusion of hydrophobic guest molecules.

Responsive microgels and microgel assemblies in biocatalytic applications

“…Amylose has a helical structure with a hydroxyl group protruding towards the exterior, making the interior of the structure relatively hydrophobic, which makes the system amenable to capturing and hosting hydrophobic molecules (Figure 1C). 42 Controlled radical polymerization methods, which include atom transfer radical polymerization (ATRP), and reversible-addition-fragmentation chain transfer (RAFT) polymerization, have been used to synthesize controlled MW, low PDI copolymers with variable chemical composition for microgel preparation. However, F I G U R E 1 Microgel synthesis: (A) multi-step preparation of PHEAA microgels.…”

“…(C) Phosphorylase‐catalyzed grafting from polymerization of amylose‐coated biohybrid microgels. Reprinted with permission from Reference [42] Copyright© 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim. (D) Reactor setup for continuous synthesis of thermoresponsive microgel and COSMOL simulation of heat transfer to determine the time at which reaction temperature is reached.…”

“…Amylose has a helical structure with a hydroxyl group protruding towards the exterior, making the interior of the structure relatively hydrophobic, which makes the system amenable to capturing and hosting hydrophobic molecules (Figure 1C). 42 …”

Multi‐Responsive Biodegradable Cationic Nanogels for Highly Efficient Treatment of Tumors

“…Normally, the cationic NGs with abundant amino groups can be synthesized by two ways: 1) The crosslinking of the primary amine‐based polymers using miniemulsion method, [ 10c ] and 2) the polymerization of primary amine functional monomers with hydrochloride protection, [ 16 ] because of the presence of free primary and secondary amines making the polymerization impossible. However, the former are complex operating procedures, hard‐to‐purify attributes, low yields, and non‐uniform size distribution.…”

Glucose and Maltose Surface-Functionalized Thermoresponsive Poly(N-Vinylcaprolactam) Nanogels

“…In fact, in many of the application areas in which PNVCL nanogels are envisioned to be of importance, their properties could benefit from carbohydrate coating (drug delivery, biomimetic systems, and biomolecule scavenging/sensing). The examples on carbohydrate-modified hydrogel particles are limited in the literature, − and only a few examples of PNVCL hydrogel particles bearing carbohydrates can be found. , Herein, we opted to modify the PNVCL hydrogel particle surfaces with glucosides and maltosides bearing different linker lengths and examine the effects on the structural and colloidal properties of the end products. The carbohydrates were chosen because glucose and its glycopolymers are widely used by organisms, and maltosides have recently been shown to bind to the noncanonical binding site of galectin-3, a lectin that plays an important role in innate immunity .…”