Search for: All records

Abstract Supercritical Impregnation methods are becoming popular in the development of food packaging materials. Bulk functional improvements of cellulose substrates using this method may be influenced by interfacial interactions between the impregnated solutes and cellulose. Hence, an interfacial adsorption kinetics study of solute molecules onto the substrate can provide insight on bulk property development, leading to an optimized packaging material with improved functionality. Paper substrates were impregnated with two food-grade waxes: Alkyl Ketene Dimer (AKD) and Carnauba Wax (CW). Hydrophobic development was monitored over a 3-week period. A quartz crystal microbalance (QCM-D) was used to determine interfacial characteristics and behavior of each wax with cellulose, and adsorption kinetics were quantified to compare the mass transfer processes of each wax at the interface. AKD significantly contributed to the substrate’s hydrophobic development over time. CW generated mildly hydrophobic substrates only when heated. AKD strongly adhered to the cellulose fibers at the interface, and demonstrated a 3-stage kinetic adsorption process, tentatively assigned (i) diffusion through the solvent; (ii) diffusion through the substrate; and (iii) attachment onto the fibers. CW readily washed off the cellulose surface, demonstrating only the first adsorption process. The different chemical structures also impacted these behaviors, as did concentration and temperature. Graphical Abstract 

Abstract A quartz crystal microbalance (QCM) is an instrument that has the ability to measure nanogram‐level changes in mass on a quartz sensor and is traditionally used to probe surface interactions and assembly kinetics of synthetic systems. The addition of dissipation monitoring (QCM‐D) facilitates the study of viscoelastic systems, such as those relevant to molecular and cellular mechanics. Due to real‐time recording of frequency and dissipation changes and single protein‐level precision, the QCM‐D is effective in interrogating the viscoelastic properties of cell surfaces and in vitro cellular components. However, few studies focus on the application of this instrument to cytoskeletal systems, whose dynamic parts create interesting emergent mechanics as ensembles that drive essential tasks, such as division and motility. Here, we review the ability of the QCM‐D to characterize key kinetic and mechanical features of the cytoskeleton through in vitro reconstitution and cellular assays and outline how QCM‐D studies can yield insightful mechanical data alone and in tandem with other biophysical characterization techniques.