Synthetic chemoreceptive membranes. Sensing bitter or odorous substances on a synthetic lipid multibilayer film by using quartz-crystal microbalances and electric responses

Abstract

Specific adsorptions of bitter or odorous substances on a synthetic lipid multibilayer matrix (2C18N+2C1/PSS-) were detected by observing frequency changes of a multibilayer-coated quartz-crystal microbalance (QCM). Partition coefficient (P) and diffusion constants (D) of these substances in the lipid matrix could be obtained quantitatively by using the QCM method. There were good correlations between partition coefficients of various bitter or odor substances to the synthetic multibilayer film on the QCM and the intensity of bitter tastes or olfactory receptions in humans: the stronger the intensity of a bitter substance or odorant, the greater the adsorption on the lipid matrix. This indicates that the lipid-coated QCM acts as a sensitive and selective sensor for bitter taste and odor. Electric responses (changes of membrane potential and membrane resistance) of the 2C18N+2C1/PSS-film occurred consecutively by the adsorption of these substances. The bitter or odor substance showing the stronger intensity induced membrane potential change in lower concentrations. It was found that bitter substances having sterically bulky molecular structures adsorb on the surface of the lipid matrix, and the phase-boundary potential of the membrane is thereby changed. On the contrary, odor substances with relatively small or slender structures can penetrate into the lipid matrix and cause reduction of the membrane resistance (the increase of ion permeability). The selective adsorption behavior of bitter and odor substances by molecular shapes was confirmed by adsorption studies of simple C9-10 hydrophobic alcohols having various molecular structures.

Stainless and Titanium Fibers as Non-degradable Three-dimensional Scaffolds for Bone Reconstruction

“…In the present study, the adsorption behavior of fibronectin to stainless steel and titanium was monitored by the QCM method, a simple technique to detect molecular behavior on a surface. Okahata et al 20,21) reported a pioneering study using the QCM technique to detect the interaction of various biomolecules, such as deoxyribonucleic acid (DNA), peptide and carbohydrate. Hayakawa et al 22) also monitored the complex formation between DNA and basic fibroblast growth factor using the QCM method.…”

Polymer thin film photodegradation and photochemical crosslinking: FT-IR imaging, evanescent waveguide spectroscopy, and QCM investigations

“…The QCM is a highly sensitive technique for observing mass changes due to physical or chemical changes occurring in a thin layer of material deposited on a quartz crystal [24]. The piezoelectric properties of the crystal changes with mass adsorption at the interface of the crystal and air, causing a change in the oscillating frequency F q .…”

Adsorption and Desorption of Beer and Coffee on a Lipid Membrane as Related to Sensory Bitterness

“…A quartz-crystal microbalance (QCM, 9 MHz, AT cut) was connected to an oscillator designed to drive the quartz at its resonance fre-quency in an aqueous solution according to the method employed by Okahata et al 16,17 . The QCM is driven at 5 V dc, and the frequency of the oscillating quartz is measured by a frequency counter attached to a personal computer system (Think Pad, IBM).…”

“…The frequency change increased with increasing beer volume and with increasing temperature (data not shown). It is known that the QCM is a very sensitive mass-measuring device at the nanogram level, because the resonance frequency changes sharply upon deposition of a given weight on the electrode 16,17 . The calibration of the QCM has shown that a frequency decrease of 1 Hz corresponds to a mass increase of 1.05 ± 0.01 ng on the electrode of the QCM.…”