JPH04215042A - Bitter material detecting element - Google Patents

Abstract

PURPOSE:To obtain a bitter material detecting element easy in element solidification and capable of detecting bitter material in such a way as to correspond to the bitterness sensed by a human being. CONSTITUTION:A bitter material detecting element 5 is of structure provided with a mixed film 4, containing lipid and fluorescent material, formed on a base 1, and detects a bitter material quantity with this mixed film 4 attracted thereto by radiating excitation light to the fluorescent material and measuring fluorescence emitted from the fluorescent material.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element for detecting bitter substances, and more particularly to a bitter substance detection element that can be easily constructed as a solid-state element.

0002

2. Description of the Related Art Japanese Patent Application Laid-Open No. 63-222248 discloses a method for detecting bitter substances. In this prior art,
By adsorbing a bitter substance onto an immobilized bilayer membrane containing lipids and measuring changes in membrane potential and/or membrane resistance due to the adsorption, or by immobilizing a bilayer membrane on a crystal oscillator, A method of detecting a bitter substance by measuring the amount of the bitter substance adsorbed on a molecular film by measuring the decrease in the oscillation frequency of a crystal oscillator is disclosed. In the method of measuring changes in membrane potential and/or membrane resistance, a measuring aqueous phase is placed on one side of a bilayer membrane, a reference aqueous phase is placed on the other side, and each of the measuring aqueous phase and the reference aqueous phase is A silver-silver chloride electrode or the like is inserted, and the potential or membrane resistance is determined by the potential difference between the two electrodes. In addition, in the method using a crystal oscillator, the detection element is constructed by forming a bilayer film on one electrode of a crystal oscillator, which has electrodes formed on both main surfaces of the bilayer film. The adsorption amount of bitter substances is determined by immersing the device in pure water, injecting bitter substances into the water, and measuring the frequency difference before and after injection.

0003

[Problems to be Solved by the Invention] However, among the detection methods described in the above-mentioned prior art, in the method of measuring changes in membrane potential, as described above, a bilayer membrane is separated into a measuring aqueous phase and a reference water phase. Therefore, it was difficult to solidify the bitter substance sensing element.

[0004] Also, in the method of measuring changes in membrane resistance, it is necessary to construct a sensing element in the same manner as described above, so it is also difficult to construct it as a solid-state element. Furthermore, it is unclear whether the magnitude of change in membrane resistance is correlated with the intensity of bitterness felt by humans. moreover,
The detection method using a crystal oscillator detects based on changes in weight, so in the case of an unknown bitter substance whose molecular weight is unknown, the correlation between the amount of adsorption and the bitterness intensity felt by humans is unknown. There was a problem.

[0005] An object of the present invention is to provide a bitter substance sensing element that can be constructed as a solid sensing element and that can detect the amount of a bitter substance in a manner that correlates with the intensity of bitterness felt by humans. There is a particular thing.

[0006]

Means and Effects for Solving the Problems The bitter substance detection element of the present invention is characterized in that it detects bitter substances by measuring fluorescence emitted from a fluorescent substance. That is, the bitter substance detection element of the present invention is made of a material that transmits excitation light for exciting the fluorescent substance used and the fluorescence emitted from the fluorescent substance, and does not emit fluorescence even when irradiated with the excitation light. and a mixed film formed on the substrate and made of a lipid and a fluorescent substance.

The configuration of the present invention will be explained in more detail below. The substrate may be made of any suitable material as long as it transmits the excitation light for exciting the fluorescent substance used and the fluorescence emitted from the fluorescent substance and does not emit fluorescence due to the excitation light. For example, those made of quartz glass, borosilicate glass, synthetic sapphire, mica, polymethacrylic acid methacrylate (PMMA), polycarbonate, or polyethylene terephthalate (PET) are used.

[0008] Furthermore, the mixed film formed on the substrate is constructed by mixing the following lipids and fluorescent substances. The lipids that can be used include those with 12 to 2 carbon atoms in the molecule.
A compound having two or three long-chain saturated or unsaturated hydrocarbon groups of 0 and an ester bond with a carboxyl group or carboxylic acid or an ester bond with phosphoric acid is used.

Specifically, esters of phosphatidylcholine, phosphatidylserine, etc. and long-chain carboxylic acids, esters of long-chain alcohols and phosphoric acid, dicarboxylic acids, or tricarboxylic acids, etc. can be used. Examples of the phosphatidylcholine that can be used include dipalmitoylphosphatidylcholine, distearoylphosphatidylcholine, dioleoylphosphatidylcholine, and the like. Examples of phosphatidylserine include dipalmitoylphosphatidylserine, distearoylphosphatidylserine, dioleoylphosphatidylserine, and the like. Examples of the phosphoric acid ester include di-n-hexadecyl phosphate, di-n-octadecyl phosphate, dioleyl phosphate, and the like. Examples of dicarboxylic acid esters include palmityl ester, stearyl ester, and oleyl ester of malonic acid or succinic acid.

[0010] The above-mentioned various compounds may be used alone, or two or more of the above-mentioned lipid compounds may be used as a mixture. Furthermore, a mixture of these lipid compounds and cholesterol may be used. It's okay. The fluorescent substances used in the present invention include various dyes such as cyanine dyes, merocyanine dyes, rhodamine dyes, oxonol dyes, or styryl dyes, fused aromatic ring derivatives such as anthracene, pyrene, or perylene,
Alternatively, an organometallic complex or the like can be used.

Among the above, as cyanine dyes, 3
, 3'-dioctadecyl-2,2'-oxacarbocyanine, 1,1'-dioctadecyl-3,3,3',3'
-tetramethyl-2,2'-indocarbocyanine, or 1,1'-dioctadecyl-3,3,3',3'-
Examples include salts such as tetramethyl-2,2'-(4,5,4',5'-dibenzo)-indodicarbocyanine. Examples of merocyanine dyes include 3-carboxymethyl-5-[2-(3-octadecyl-2-benzothiazolinylidene)ethylidene]-rhodamine, and examples of rhodamine dyes include [9 -(o-carboxyphenyl)-6-diethylamino-3H-xanthene-
3-ylidene]-N-ethyl-N-octadecylammonium, or [9-(o-carboxyphenyl)-6
-(N-ethyl-N-octadecylamino)-3H-xanthene-3-ylidene]-N-ethyl-N-octadecylammonium and the like.

The above-mentioned mixed film consisting of lipid and fluorescent substance can be formed by various methods, including the LB method (La
Although it is preferable to form the membrane by the ngmuir-Blodgett method, after the lipid membrane is formed, a fluorescent substance may be included in the lipid membrane by a method such as staining. Further, it is preferable that the mixed membrane is a laminate of two or three layers of mixed membranes, and that the surface thereof is hydrophilic.

The present invention has a structure in which a mixed film of the above-mentioned lipid and fluorescent substance is formed on a substrate, and the amount of bitter substances is detected by measuring the fluorescence intensity of the fluorescent substance. The sensing element can be easily solidified.

[0014]

EXAMPLES The present invention will now be explained by describing non-limiting examples thereof. As a lipid, di-
n-hexadecyl phosphate, a cyanine dye represented by the following formula (A) as a fluorescent substance, namely 3,3'-dioctadecyl-2,2'-oxacarbocyanine perchlorate (hereinafter referred to as cyanine dye A) (omitted) was used.

[0015]

[Chemical formula 1]

Dihexadecyl phosphate (molecular weight: 5
46.86), 2.6 mg of cyanine dye A (molecular weight 881.72), and chloroform 10
Dissolved in ml. 40 μl of the obtained solution was spread on the water surface of the LB film deposition apparatus, and the surface pressure was maintained at 40 mN/m.
A two-layer film was formed on a transparent quartz substrate by the LB method, with the first layer being pulled up while the substrate was being pulled up, and the second layer being pushed down. A structure in which a mixed film is formed on a transparent substrate in this manner is schematically shown in FIG. In FIG. 1, 1 is a transparent quartz substrate, 2 is a dihexadecyl phosphate molecule, 3 is a cyanine dye A molecule, 4 is a mixed film, and 5 is a bitter substance sensing element.

Next, the bitter substance detection element 5 shown in FIG. 1 was fixed in a measurement cell 6 as shown in FIG. The measurement cell 6 was made of quartz glass, and the detection element 5 was contacted and fixed to one inner wall of the measurement cell 6. Next, the measurement cell 6 was filled with an aqueous solution 7 containing quinine as a bitter substance, and the fluorescence intensity was measured using a spectrofluorometer (manufactured by JASCO Corporation; FP-777). In the measurement, the concentration of the quinine aqueous solution filled in the cell was changed, and at various concentrations, excitation light of 450 nm was applied.
The intensity at a fluorescence wavelength of 520 nm was measured, where m is the fluorescence wavelength.

The fluorescence intensity measured as described above is shown in Table 1 below.

[0019]

[Table 1]

As is clear from Table 1, the fluorescence intensity changes as the concentration of quinine, a typical bitter substance, changes. Let F0 be the fluorescence intensity for water that does not contain quinine, F1 be the fluorescence intensity for quinine aqueous solution, and plot the rate of change in fluorescence intensity with respect to quinine concentration (F1 - F0)/F0 × 100 (%) against quinine concentration. As a result, the results shown in FIG. 3 were obtained. Since the threshold value of quinine is about 2 x 10-6 mol/l, it can be seen from FIG. 3 that it is possible to measure concentrations up to the vicinity of the threshold value. Furthermore, it is said that the intensity of bitterness felt by humans is proportional to the logarithm of the concentration of bitter substances;
Since the characteristics of the bitter substance sensing element also depend on the logarithm of the concentration, it can be seen that the bitterness intensity felt by humans can be measured with the bitter substance sensing element of this example.

[0021]

[Effects of the Invention] According to the present invention, a bitter substance detection element is constructed by forming a mixed film of the above-mentioned lipid and fluorescent substance on a substrate, and by measuring the fluorescence intensity of the fluorescent substance. Since the amount of a bitter substance is detected, it is possible to solidify the bitter substance detection element. Furthermore, as is clear from the examples, the bitter substance detection element of the present invention can detect the amount of bitter substances in a manner that correlates with the intensity of bitterness felt by humans.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the configuration of a bitter substance detection element prepared in an example.

FIG. 2 is a schematic plan view for explaining the process of measuring fluorescence intensity in Examples.

FIG. 3 is a diagram showing the results of Examples and showing the relationship between the quinine concentration and the rate of change in fluorescence intensity.

[Explanation of symbols]

1 Transparent quartz substrate 2 Dihexadecyl phosphate molecule 3
Molecule of cyanine dye A 4 Mixed membrane 5 Bitter substance detection element 6 Measurement cell

Claims (1)

[Claims] Claim 1: A bitter substance detection element that detects a bitter substance by measuring fluorescence emitted from a fluorescent substance, which transmits excitation light for exciting the fluorescent substance used and the fluorescence emitted from the fluorescent substance. A bitter substance sensing element, comprising: a substrate made of a material that does not emit fluorescence when exposed to the excitation light; and a mixed film formed on the substrate and made of a lipid and a fluorescent substance. .