Coaxial Electrospun Fibermat of Poly(AM/DAAM)/ADH and PCL: Versatile Platform for Functioning Active Enzymes

Abstract

In this study, we prepared and characterized enzyme (α-chymotrypsin or lactase)-encapsulating core-shell fibermats by electrospinning. The hydrophilic copolymer of acrylamide (AM) and diacetone acrylamide (DAAM), poly(AM/DAAM), was used as the base material to obtain the core unit of nanofibers. During electrospinning, poly(AM/DAAM) was crosslinked with the bifunctional crosslinker adipic acid dihydrazide (ADH) in the presence of enzyme molecules. The cores were wrapped with hydrophobic poly(ε-caprolactone) (PCL) layers as shell unit. Different from the fibermats of only poly(AM/DAAM)/ADH, the core-shell fibermat of poly(AM/DAAM)/ADH and PCL exhibited sufficient mechanical strength and stability of the stacked nanofibrous structure in a neutral-pH buffer. Furthermore, when the PCL-shell thickness was controlled to be less than 150 nm, the encapsulated enzymes exhibited an apparent activity of >70–80% for low-molecular weight substrates in an immersion buffer. These results indicate that the core-shell fibermats of poly(AM/DAAM)/ADH and PCL (or other hydrophobic polymer) could be used as effective enzyme-immobilizing platforms.

Core–shell fibremats comprising a poly(AM/DAAM)/ADH nanofibre core and nylon6 shell layer are an attractive immobilization platform for constructing immobilised enzymes

“…17 In our previous study, we called this method for constructing the protein-encapsulated bremats the 'in situ cross-linking during electrospinning' (SCES) method. 1,17 Poly(AM/DAAM) was synthesised by reversible addition-fragmentation chain-transfer (RAFT) polymerisation 28 using AM and DAAM (the AM : DAAM molar ratio was set at 4 : 1), the RAFT reagent 2-(2-carboxyethylthiocarbonothioylthio) propionic acid, and the initiator VA-057, as described in a previous study. 17 The M n and polydispersity were 46 400 and 1.55, respectively, from the gel permeation chromatography (GPC) analysis.…”

“…Recently, we developed techniques for immobilising and functionalising enzymes inside bremat nanobres (e.g., 'into a substrate'). 1,[15][16][17] First, the bremats must be insoluble in aqueous buffers. However, choosing water-insoluble hydrophobic polymers as a bremat base material in the rst step for preparing the electrospinning precursor solutions, including the hydrophobic polymer (i.e., bremat base material) and proteinous enzymes, is difficult because no suitable solvents are available for solubilising both without denaturing the proteinous enzymes.…”

“…, ‘into a substrate’). 1,15–17 First, the fibremats must be insoluble in aqueous buffers. However, choosing water-insoluble hydrophobic polymers as a fibremat base material in the first step for preparing the electrospinning precursor solutions, including the hydrophobic polymer ( i.e.…”

Synthesis of Cross‐Linked Block Copolymer Nanoassemblies and their Coating Application

“…[15][16][17][40][41][42] However, their practical applications of cross-linked block copolymer nanoassemblies are rather limited. [33,43] As well-known, core-cross-linked block copolymer nanoassemblies dispersed in water have the character, that the hydrophobic block is crosslinked and the block copolymer nanoassemblies are hard to be dissolved or solvated when a cosolvent is added. [34,44] Therefore, coalescence of core-cross-linked block copolymer nanoassemblies is restricted, which makes them unsuitable for coating application, in which mechanical properties and water resistance are essential.…”

“…[30,31] Of all the cross-linking moieties, diacetoneacrylamide (DAAM) with adipic acid dihydrazide (ADH) is the most favorable. [32][33] The most remarkable feature of the keto-hydrazide crosslinking reaction is fast curing at room temperature, [34] providing great convenience in synthesis of cross-linked block copolymer nanoassemblies. The second method to prepare crosslinked block copolymer nanoassemblies is based on duringpolymerization cross-linking.…”