Functionalization of cellulosic model substrates via laccase-mediated coupling of non-polar particles

Abstract

In the present work we investigate the physicochemical interactions between silica and nanofibrillar cellulose (CNF) with a multi component system (MCS) obtained from an enzymatic reaction of a laccase enzyme and a short-chain organic molecule, dodecyl 3,4,5-trihydroxybenzoate (commonly known as lauryl gallate, LG) as well as sulphonated lignin (SL). Hydrophobic chains of enzyme-modified LG were coupled onto CNF and silica surfaces by direct adsorption of the MCS. Quartz crystal microgravimetry (QCM-D), Atomic Force Microscopy (AFM) and water contact angle (WCA) were used to monitor in situ and characterize the hydrophobization process. Efficient adsorption of the MCS onto CNF and silica surfaces increased their WCA by 88° and 78°, respectively. Dynamic Light Scattering (DLS) measurements revealed an effect of the enzyme on LG: reducing particle size from several microns down to 300 nm. The laccase (Lacc) treatment in the presence of SL reduced even more the LG particle size to 80 nm through a dispersive effect of SL