by Keyword: Quartz

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Redondo-Morata, Lorena, Losada-Pérez, Patricia, Giannotti, Marina Inés, (2020). Lipid bilayers: Phase behavior and nanomechanics Current Topics in Membranes (ed. Levitan, Irena, Trache, Andreea), Academic Press (Berlin, Germany) 86, 1-55

Lipid membranes are involved in many physiological processes like recognition, signaling, fusion or remodeling of the cell membrane or some of its internal compartments. Within the cell, they are the ultimate barrier, while maintaining the fluidity or flexibility required for a myriad of processes, including membrane protein assembly. The physical properties of in vitro model membranes as model cell membranes have been extensively studied with a variety of techniques, from classical thermodynamics to advanced modern microscopies. Here we review the nanomechanics of solid-supported lipid membranes with a focus in their phase behavior. Relevant information obtained by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) as complementary techniques in the nano/mesoscale interface is presented. Membrane morphological and mechanical characterization will be discussed in the framework of its phase behavior, phase transitions and coexistence, in simple and complex models, and upon the presence of cholesterol.

Keywords: Lipid phase behavior, Phase transition, Phase coexistence, Nanomechanics, Thermodynamics, Atomic force microscopy (AFM), Quartz crystal microbalance with dissipation monitoring (QCM-D)

Botaya, Luis, Otero, Jorge, González, Laura, Coromina, Xavier, Gomila, Gabriel, Puig-Vidal, Manel, (2015). Quartz tuning fork-based conductive atomic force microscope with glue-free solid metallic tips Sensors and Actuators A: Physical , 232, 259-266

Abstract Here, we devise a conductive Atomic Force Microscope (C-AFM) based on quartz tuning forks (QTFs) and metallic tips capable of simultaneously imaging the topography and conductance of a sample with nanoscale spatial resolution. The system is based on a header design which allows the metallic tip to be placed in tight and stable mechanical contact with the QTF without the need to use any glue. This allows electrical measurements to be taken with an electrically excited QTF with the two prongs free. The amplitude oscillation of the QTF is used to control the tip-sample distance and to acquire the topographic images. Meanwhile, the metallic tip is connected to a current–voltage amplifier circuit to measure the tip-sample field emission/tunneling current and to produce the conductive images. This method allows decoupled electrical measurement of the topography and electrical properties of the sample. The results we obtain from calibration samples demonstrate the feasibility of this measurement method and the adequacy of the performance of the system.

Keywords: AFM, Conductive AFM, Quartz tuning fork

Rodriguez-Segui, S. A., Bucior, I., Burger, M. M., Errachid, A., Fernàndez-Busquets, X., (2009). Application of the quartz crystal microbalance to the study of multivalent carbohydrate-carbohydrate adhesion Sensor Letters 6th Maghreb-Europe Meeting on Materials and Their Applications for Devices and Physical, Chemical and Biological Sensors , AMER SCIENTIFIC PUBLISHERS (Rabat, Morocco) 7, (5), 782-787

Carbohydrate-carbohydrate interactions in cell adhesion are being increasingly explored as important players in cell-cell and cell-extracellular matrix interactions that are characterized by finelytuned on-off rates. The emerging field of glycomics requires the application of new methodologies to the study of the generally weak and multivalent carbohydrate binding sites. Here we use the quartz crystal microbalance (QCM) for the analysis of the self-binding activity of the g200 glycan, a molecule of marine sponge origin that is responsible for Ca2+-dependent species-specific cell adhesion. The QCM has the advantages over other highly sensitive techniques of having only one of the interacting partners bound to a surface, and of lacking microfluidics circuits prone to be clogged by self-aggregating glycans. Our results show that g200 self-interaction is negligible in the absence of Ca2+. Different association kinetics at low and high Ca2+ concentrations suggest the existence of two different Ca2+ binding sites in g200. Finally, the observation of a non-saturable binding indicates that g200 has more than one self-adhesion site per molecule. This work represents the first report to date using the QCM to study carbohydrate-carbohydrate interactions involved in cell adhesion.

Keywords: Ca2+-dependent binding, Carbohydrate-carbohydrate interaction, Cell adhesion, Proteoglycan, Quartz crystal microbalance, Sponges

Rodriguez, Segui, Bucior, I., Burger, M. M., Samitier, J., Errachid, A., Fernàndez-Busquets, X., (2007). Application of a bio-QCM to study carbohydrates self-interaction in presence of calcium Transducers '07 & Eurosensors Xxi, Digest of Technical Papers 14th International Conference on Solid-State Sensors, Actuators and Microsystems , IEEE (Lyon, France) 1-2, 1995-1998

In the past years, the quartz crystal microbalance (QCM) has been successfully applied to follow interfacial physical chemistry phenomena in a label free and real time manner. However, carbohydrate self adhesion has only been addressed partially using this technique. Carbohydrates play an important role in cell adhesion, providing a highly versatile form of attachment, suitable for biologically relevant recognition events in the initial steps of adhesion. Here, we provide a QCM study of carbohydrates' self-recognition in the presence of calcium, based on a species-specific cell recognition model provided by marine sponges. Our results show a difference in adhesion kinetics when varying either the calcium concentration (with a constant carbohydrate concentration) or the carbohydrate concentration (with constant calcium concentration).

Keywords: Biomedical materials, Calcium, Cellular biophysics, Microbalances, Porous materials, Quartz, Surface chemistry/ bio-QCM, Carbohydrates self-interaction, Quartz crystal microbalance, Interfacial physical chemistry phenomena, Carbohydrate self adhesion, Biologically relevant recognition events, Marine sponges, Adhesion kinetics, Calcium concentration, Carbohydrate concentration, Biosensors, Biomedical materials, Surface chemistry, Cellular biophysics