Laccase Complex with Polyvinylamine Bearing Grafted TEMPO is a Cellulose Adhesion Primer

Abstract

Polyelectrolyte complexes formed between laccase and polyvinylamine with grafted TEMPO moieties, PVAm-T, adsorb onto cellulose, causing oxidation. All evidence supports the view that aldehyde groups on oxidized cellulose condense with primary amine groups, giving a grafted layer of PVAm-T complexed with laccase. The grafted PVAm-T serves as a primer layer promoting wet cellulose-to-cellulose adhesion in the presence of PVAm adhesive. The cellulose modification occurs at ambient temperatures and pH 5. The adhesion improvements with mixtures of PVAm-T and laccase are remarkable because both components are macromolecular, which should inhibit the ability of the TEMPO to act as a shuttle between the enzyme and the primary hydroxyl groups on cellulose. It is proposed that PVAm-bound oxoammonium ions exchange with neighboring TEMPO moieties, providing a mechanism for the transfer of oxidation activity from immobilized enzyme to the cellulose surfaces.

Laccase‐Mediated Grafting on Biopolymers and Synthetic Polymers: A Critical Review

“…For many grafting applications, the outermost layer of the material should be activated, but its internal consistency should not be altered. Because TEMPO‐mediated oxidations of cellulose decrease the degree of polymerisation, Liu and co‐workers developed an immobilised TEMPO–poly(vinylamine) complex (PVAm‐T) and used this as a mediator in the laccase‐mediated oxidation of cellulose . It was proposed that some surface C6 hydroxy groups were oxidised to the aldehyde first, which would then form imine bonds with the remaining amine groups of PVAm‐T (Scheme ).…”

“… PVAm‐T/laccase complex grafted on cellulose for the laccase‐mediated oxidation of TEMPO followed by “oxidation‐state transfer” to oxidise cellulose. Based on work by Liu et al …”

“…Aldehydes were labelled with green fluorescein‐5‐thiosemicarbazide. Reproduced with permission from Liu et al . Copyright American Chemical Society, 2013.…”

“…Because TEMPO-mediated oxidations of cellulose decrease the degree of polymerisation, Liu and coworkers developed an immobilised TEMPO-poly(vinylamine) complex (PVAm-T) and used this as am ediator in the laccasemediated oxidation of cellulose. [88] It was proposed that some surfaceC 6h ydroxy groups were oxidised to the aldehyde first, which would then form iminebonds with the remaining amine groups of PVAm-T( Scheme 18). Since PVAm-T is still positively chargeda nd laccase is slightly negatively charged, they formed aP VAm-T/laccase complex on the surface.…”

Synthesis of Novel Nitroxide Radical Polymer Materials for Imaging and Energy Storage Applications

“…Later, the same authors replaced the bleach in the secondary oxidation cycle with an enzyme, laccase. 279 Laccase, in conjunction with oxygen, is acting as a terminal oxidant, promoting the conversion of hydroxylamine to oxoammonium cation. Using an enzyme is more environmentally friendly and allows more moderate reaction conditions (near neutral pH) to be employed, opposed to the strong oxidizing power of bleach at high pH.…”