In situ surface-detecting technique by using a quartz-crystal microbalance. Interaction behaviors of proteins onto a phospholipid monolayer at the air-water interface

Characterization of Ferritin Adsorption onto Gold

“…Minimization of the applied force was achieved by reducing the cantilever deflection until the feed-concentration in PBS is increased. Maximum frequency linked with shape, size, and hydrophobicity of the adsorbed proteins when they are in contact with solution (13,(62)(63)(64). For example, for the relatively large hydrophilic protein immunoglobulin G (IgG) (M W 10 5 ), the frequency is enhanced by a factor of ca.…”

“…For example, for the relatively large hydrophilic protein immunoglobulin G (IgG) (M W 10 5 ), the frequency is enhanced by a factor of ca. 1.8 (13,62), whereas for small (M W õ 5000) hydrophobic proteins no frequency enhancement is found (62,63). Since the QCM responds not only to protein mass uptake, but also to other interfacial mass change when in contact with solution, Eq.…”

“…The DF PBS values are a factor of 2.28 larger than the frequency shifts observed when the ferritin film is dry (DF air ). The enhancement in frequency can be attributed to entrapped solution within the wet ferritin film and/or to the protein molecules vibrating on the QCM with surrounding water when in contact with solution (13,(62)(63)(64). The possibility that goldadsorbed ferritin was removed during rinsing is excluded, given that ferritin was found to be irreversibly adsorbed; see Experimental.…”

Study of Adsorption Behavior of Bilirubin on Human-Albumin Monolayer Using a Quartz Crystal Microbalance

“…It was shown that the resonance frequency of a QCM operating in the liquid phase is influenced by the viscoelasticity of the adhesion layer and solution properties; the QCM does not behave as predicted by the Sauerbrey equation (25)(26)(27). To characterize the properties of the albumin layer on the surface of QCM, the values of R for QCM with and without humanalbumin layer were measured both in air and in solution with the impedance analysis method.…”

Biosensors Based on Acoustic Wave Devices

“…In another experimental procedure, piezoelectric crystals were attached horizontally on the phospholipid monolayer prepared in a Langmuir film balance in order to study the adsorption of mellitin and b-globulin [57]. The authors measured frequency responses both from the solution (in situ adsorption) and in air after drying, and evaluated the adsorbed mass of protein from Sauerbrey's equation.…”