A combination of surface-initiated controlled radical polymerization (SET-LRP) and click-chemistry for the chemical modification and fluorescent labeling of cellulose nanofibrils: STED super-resolution imaging of a single fibril and a single fibril embedded in a composite

Abstract

A strategy is developed to modify cellulose nanofibril (CNF) surfaces with a combination of Cu0-mediated radical polymerization (SET-LRP) and CuI-catalyzed azide-alkyne click-chemistry (CuAAC). CNFs were grafted with statistical copolymers of di(ethylene glycol) ethyl ether acrylate (DEGEEA) and acrylic acid 3-trimethylsilyl-prop-2-ynyl ester (TMSPgA) that allows labeling of multiple fluorescent dyes, e.g. AF488 and ATTO633, special dyes for confocal laser scanning microscopy and stimulated emission depletion (STED) microscopy. Through our strategy and these microscopic techniques, we visualized isolated fibrils and fibrils embedded in a PVA composite in a high resolution. This work also provides new insight into the effect of the clickable entity/precursor on the compatibility of modified fibrils with the composite matrix. Graphical abstract

Multifunctional Cellulose Nanofibrils–GdF3 Nanoparticles Hybrid Gel and Its Potential Uses for Drug Delivery and Magnetic Resonance Imaging

“…In our recent works, − we have shown that the CNF surface hydroxyls can be chemically modified to act as a radical polymerization initiator for the Cu 0 -mediated single electron transfer living radical polymerization (SET-LRP), introduced by Percec et al SET-LRP is a robust polymerization technique as the reaction can be conducted in a relatively mild condition and polymerize vinyl monomers in a broad range, with full control on the grafted polymeric chain length . We employed this powerful technique and demonstrated a series of approaches to cross-link polymer-grafted cellulose nanofibrils with various inorganic nanoparticles based on SET-LRP, therefore creating different CNF-based hybrid materials with enhanced mechanical properties and unique characteristics such as UV-blocking, NIR absorption, and electrochemical properties …”