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Investigations of biofilms formed on silica in contact with aqueous formulations containing laccase and maltodextrin

: Corrales Ureña, Yendry Regina; Gätjen, Linda; Vieira Nascimento, Matheus; Lisboa-Filho, Paulo Noronha; Leite Cavalcanti, Welchy; Noeske, Paul-Ludwig Michael; Rischka, Klaus

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Applied Adhesion Science 4 (2016), Art. 2, 11 pp.
ISSN: 2196-4351
Journal Article, Electronic Publication
Fraunhofer IFAM ()

The formation of nano-scale biofilms on hydrophilic silica surfaces from aqueous polypeptide/polysaccharide mixtures containing laccase and maltodextrin was investigated in situ with quartz crystal microbalance with dissipation monitoring (QCM-D). Surface analysis techniques such as X-ray photoelectron spectroscopy (XPS), optically stimulated electron emission (OSEE) and atomic force microscopy (AFM) were applied for characterizing the resulting layers obtained after periods varying from a few seconds to several hours of contact between the substrate and the biopolymers formulation. The biofilm formation in contact with the aqueous laccase/maltodextrin suspension was studied at pH level 4.75, under conditions close to the isoelectric point of the enzyme. The few nanometers rough biofilms obtained were composed of a laccase/maltodextrin mixture, and their thickness was observed to steadily increase during 4 h of contact with the aqueous mixture of biopolymers. Remarkably, the still adhesive films obtained after 1 h of contact with aqueous polypeptide/polysaccharide mixture resisted a 30 min rinsing with acetate buffer. The biofilms growing process was monitored using OSEE, due to the effected attenuation of the UV-induced electron emission from the SiO2/Si substrate, which was found to be more pronounced than the attenuation of the photoelectrons from the substrate which contribute to the XPS signals. Layers as thin as 1 nm were detected by the OSEE.