Quartz crystal microbalance adsorption

Gao, G., Y. Wurm et al. (1997). Electrochemical quartz crystal microbalance, voltammetry, spectroelectrochemical, and microscopic studies of adsorption behavior for (7E,7 Z)-diphenyl-7,7 -diapocarotene electrochemical oxidation product. J. Phys. Chem. B 101 2038-2045. 

The changes in the mass of the surface during cyclic polarization of the electrode provide information on the amounts of deposited or stripped substances, adsorption, and surface hydration. The first report on the in situ use of quartz crystal microbalances for determination of the mass change of an electrode was given by Nomura and lijima. The experimen-... 

Electrochemical quartz crystal microbalance (EQCM) has been used [65] to study adsorption/desorption of iodide on Au(lll) electrodes. The coverages obtained at different potentials were quite close to those estimated from STM images and SXS measurements. 

Jusys and Bruckenstein [84] have used electrochemical quartz crystal microbalance to study adsorption/desorption of perchlorate and perrhenate ions on a bare polycrystalline Au electrode. The change in the equivalent mass was undoubtedly assigned to the adsorption of both anions in the double-layer region of Au electrode. 

Other Sulfur Compounds and Complex Adsorption Layers Adsorption of 5-(octyldithio)-2-nitrobenzoic acid on a gold electrode has been investigated using a quartz crystal microbalance [177]. 

On a pc-Au electrode in 1 M NaF vertically oriented pyridine molecules have been observed at 0.7 V (versus Ag/AgCl), applying in situ IR. In contrast, they have not been detected at this potential in electrochemical method [240]. Considering the fact that adsorption of pyridine on gold electrodes is a replacement reaction and taking into account the results obtained from quartz crystal microbalance experiments, the conclusion has been made that adsorption of one pyridine molecule is accompanied by the removal of 10-12 water molecules [241]. 

Pb UPD on polycrystalline An electrode in 0.1 M perchloric acid solution has been studied by Henderson et al. [484]. In this study, CV, electrochemical quartz crystal microbalance (EQCM), and probe beam deflection methods have been used. It has been found that Pb UPD proceeds in three steps. The first step comprised water ejection from the gold surface. This step was followed by metal UPD accompanied by the removal of the adsorbed OH. Also, Zeng and Bruckenstein have studied UPD and adsorption of Pb on pc-Au electrodes, applying XPS and TOF-SIMS method in case of 0.1 M NaCl electrolyte [485], and EQCM in case of 0.1 M NaCl04 and 0.1 M NaCl electrolytes [486]. In the presence of chloride anions, the adsorption of Pb—Cl complex has been found. 

More recently methods have also been developed to measure the adsorbed amount on single surfaces and not onto powders. Adsorption to isolated surfaces can, for instance, be measured with a quartz crystal microbalance (QCM) [383]. The quartz crystal microbalance consists of a thin quartz crystal that is plated with electrodes on the top and bottom (Fig. 9.11). Since quartz is a piezoelectric material, the crystal can be deformed by an external voltage. By applying an AC voltage across the electrodes, the crystal can be excited to oscillate in a transverse shear mode at its resonance frequency. This resonance frequency is highly sensitive to the total oscillating mass. For an adsorption measurement, the surface is mounted on such a quartz crystal microbalance. Upon adsorption, the mass increases, which lowers the resonance frequency. This reduction of the resonance frequency is measured and the mass increase is calculated [384-387],... 

Another tool used to study friction on the molecular scale is the quartz crystal microbalance (QCM) introduced in Section 9.4.1. The QCM has been used to monitor the adsorption of thin films on surfaces via the induced frequency shift [385], In the years since 1986, Krim and coworkers could show that the slippage of adsorbed layers on the QCM leads to a damping of the oscillator [472], This damping is reflected as a decrease in the quality factor Q of the oscillator. From the change in Q, a characteristic time constant rs, the so-called slip-time, can be derived. This corresponds to the time for the moving object s speed to fall to 1 /e, i.e. 

Mercury binding leads to an increase of mass of the gold layer which can be detected by electro-acoustic transducers based on quartz microbalance (QMB the abbreviation QCM = quartz crystal microbalance is also widely used), surface acoustic waves (SAW)—devices [20] or microcantilevers [21,22], Adsorption of mercury vapour increases resonance frequency of shear vibrations of piezoelectric quartz crystals (Fig. 12.2). This process can be described by Sauerbrey equation [23]. For typical AT-cut quartz, this equation is... 

Mercury interaction with gold electrodes coated by hexadecanethiol was confirmed by measurements with a quartz crystal microbalance (Fig. 12.7b) an incubation of quartz with hexadecanethiol-coated gold electrodes in the presence of mercury vapour resulted in a decrease of the resonance frequency, thus indicating an increase of the electrode mass. The adsorbed amount of mercury can be estimated from Sa-uerbrey equations the effect observed corresponds to adsorption of 0.5 pg of mercury per cm2 of the gold surface. 

As discussed above in Chapter 3, ellipsometry and quartz crystal microbalance (QCM) approaches provide a useful insight into the adsorption of both the supporting interfacial assembly and the proteins themselves. Beyond monitoring the adsorption dynamics and the structural integrity of the biomolecule, the orientation of the active site is of prime importance. For example, if the active site itself binds to the self-assembled monolayer, transport of the substrate or co-enzyme may be blocked. 

Fig. 2 Quartz crystal microbalance frequency shifts for cycles of alternate myoglobin/ds-DNA and cytochrome P450cam/ds-DNA adsorption on gold resonators coated with mixed mono-layers of mercaptoproionic acid/mercaptopropanol as first layer and PDDA as second layer. DNA was from salmon testes (ST) and calf thymus (CT). Average values are shown for five replicates of [Mb/ST ds-DNA] (0) and four replicates of [cyt P450cam/ST ds-DNA] ( ) films. (From Ref. [15] with permission. Copyright American Chemical Society.)...

To mimic the PG electrode surface for QCM measurements of layers adsorbed on the gold-quartz resonators, we first chemisorb a mixed monolayer of mercaptopropionic acid/mercaptopropanol. This layer is represented by the first point in Fig. 2, labeled MPA. The second layer is PDDA. Quartz crystal microbalance frequency decreasing in a roughly linear fashion and at regular intervals for the multiple adsorption steps demonstrates repeatable adsorption for the two DNA/en-zyme films. Relative precision of layer formation on multiple resonators within 15% can be achieved. Film thicknesses and component weights in Table 1 were obtained by analyzing the QCM data with Eqs. 1 and 2. 

Matsuura K, Tsuchida A, Okahata Y, Akaike T, Kobayashi K (1998) A quartz-crystal microbalance study of adsorption behaviors of artificial glycoconjugate polymers onto chemically modified gold surfaces and their interactions with lectins. Bull Chem Soc Jpn 71 2973-2977... 

Hook F, Vords J, Rodahl M, Kurrat R, Bdni P, Ramsden JJ, Textor M, Spencer ND, Tengvall P, Gold J, Kasemo B (2002) A comparative study of protein adsorption on titanium oxide surfaces using in situ ellipsometry, optical waveguide lightmode spectroscopy, and quartz crystal microbalance/dissipation. Colloids Surf B Biointerfaces 24 155-170... 

Galli Marxer, C., Collaud Coen, M., and Schlapbach, L. (2003). Study of adsorption and viscoelastic properties of proteins with a quartz crystal microbalance by measuring the oscillation amplitude. J. Colloid Interface Sci., 261, 291-298. 

Hook, F., Kasemo, B., Nylander, T., Fant, C., Sott, K., and Elwing, H. (2001). Variations in coupled water, viscoelastic properties, and film thickness of a Mefp-1 protein film during adsorption and cross-linking A quartz crystal microbalance with dissipation monitoring, ellipsometry, and surface plasmon resonance study.y4na/. Chem., 13, 5796-5804. 

Hook, F., Rodahl, M., Brzezinski, P., and Kasemo, B. (1998). Energy dissipation kinetics for protein and antibody-antigen adsorption under shear oscillation on a quartz crystal microbalance. Langmuir 14, 729-734. 

Dickert and co-workers [18] have made an innovative advance by applying polyurethane-based MIPs to quartz crystals for the selective detection of solvent vapours (see also Section 20.2.5.8. and Chapter 21). Electrodes may be attached to quartz crystals to form quartz crystal microbalances (QCMs), wherein minute increases in the mass of the device (for example, upon adsorption of solvent vapour) result in a decrease of the resonant frequency of the crystal. For crystals... 

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