Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving urea or urease
Reexamination Certificate
1998-06-04
2002-04-30
Navarro, Mark (Department: 1645)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving urea or urease
C435S007100, C435S007320, C436S512000, C436S501000, C422S067000, C422S051000, C422S081000
Reexamination Certificate
active
06379910
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus and a method for, in a diagnosis, a food inspection, or the like, measuring a material (for example, an enzyme) or an organism (for example, a cell or a microorganism) which decomposes a substrate in a solution and induces a pH-change of the solution.
2. Related Art
In the fields of medicine and food, it is requested to specifically and rapidly make a measurement on a trace amount of a material or an organism which can induce a pH-change of substrate solution. A material or an organism which can induce a pH-change of substrate solution can be detected by using a pH electrode. Generally, it cannot be insisted that a measurement using a pH electrode is sufficiently high in specificity and sensitivity. In order to improve this point, recently, an apparatus has been disclosed in which the specific molecular reconizability of an antibody and features of a minute pH electrode are utilized so as to perform a highly sensitive and rapid measurement (U.S. Pat. No. 5,674,696 and U.S. Pat. No. 5,066,582).
FIG. 4
shows the apparatus, and
FIG. 5
shows a state in which the apparatus is used. Portions of the apparatus will be described. A measurement cell
1
has a cylindrical shape in which an opening is formed at each of the upper and lower ends. A through hole is formed in the peripheral wall in the vicinity of the lower end and functions as a substrate solution inlet
2
. The interior of the measurement cell
1
is composed, in the sequence starting from the lower end, of a portion filled with fresh substrate solution
3
of a large diameter, a pH electrode body accommodating portion
5
of a small diameter, and a thin-tube type solid phase insertion portion
7
which is slightly larger in diameter than the pH electrode body accommodating portion
5
. A pH electrode
30
is inserted into the whole of the interior of the measurement cell. A pH electrode body portion
4
of the pH electrode
30
is accommodated in the portion filled with fresh substrate solution
3
and the pH electrode body accommodating portion
5
. A pH electrode sensing portion
6
of the pH electrode
30
is accommodated in the thin-tube type solid phase insertion portion
7
. A pH electrode connector
13
is attached to the basal end of the pH electrode
30
. The opening of the lower end of the measurement cell
1
is hermetically sealed by the pH electrode connector
13
. A reference electrode
12
is attached to the pH electrode connector
13
so as to be accommodated in the portion filled with fresh substrate solution
3
.
An annular groove is formed in the peripheral wall of the thin-tube type solid phase insertion portion
7
of the measurement cell
1
. An O-ring
8
is fitted into the groove. The O-ring
8
is used for, when a thin-tube type solid phase
19
shown in
FIG. 5
is inserted into the thin-tube type solid phase insertion portion
7
, hermetically sealing a gap between the thin-tube type solid phase
19
and the peripheral wall of the thin-tube type solid phase insertion portion
7
.
The upper end opening of the measurement cell
1
serves as a thin-tube type solid phase insertion port
9
through which the thin-tube type solid phase
19
shown in
FIG. 5
is to be inserted into the thin-tube type solid phase insertion portion
7
. The outside of the upper end of the measurement cell
1
is a substrate solution overflow portion
10
from which an overflowing substrate solution is recovered. The substrate solution which is recovered from the substrate solution overflow portion
10
reaches a waste solution vessel
16
via a substrate solution outlet
11
.
By contrast, the supply of the substrate solution to the measurement cell
1
is performed by supplying a substrate solution contained in a substrate solution vessel
15
, by a solution feed pump
14
via the substrate solution inlet
2
.
An electric circuit unit
17
has a data processing function which performs calculations on the basis of electric signals from the pH electrode
30
and the reference electrode
12
, to calculate a pH-change and supplies the calculation result to a display unit, and a drive controlling function which controls the driving of the solution feed pump
14
.
The display unit
18
performs a display corresponding to the signal supplied from the electric circuit unit
17
.
When urease secreted by Helicobacter pylori is to be detected by the thus configured apparatus, for example, a monoclonal antibody to urease secreted by Helicobacter pylori serving as a receptor is previously fixed to the inner and outer walls of the thin-tube type solid phase
19
.
The operator then soaks one end portion of the thin-tube type solid phase
19
in a sample solution for a given time period and takes out it from the sample solution. The one end portion is accommodated in the thin-tube type solid phase insertion portion
7
through the thin-tube type solid phase insertion port
9
of the measurement cell
1
. As a result, as shown in
FIG. 5
, a so-called coupling state in which the pH electrode sensing portion
6
is inserted into the thin-tube type solid phase
19
is established. Under this state, the operator instructs the electric circuit unit
17
to start the operation, so that the solution feed pump
14
is driven and the substrate solution is supplied to the interior of the thin-tube type solid phase
19
to wash the interior. After a predetermined time period elapses, the solution feed pump
14
is stopped and there occurs a pH-change in the substrate solution in the thin-tube type solid phase
19
. The electric circuit unit
17
detects the change on the basis of the output voltage of the pH electrode
30
, and the value of the detected change is displayed on the display unit
18
.
However, it has been noted that there arise the following problems in such an apparatus when the thin tube of the thin-tube type solid phase
19
is coupled with the pH electrode sensing portion
6
of the pH electrode
30
.
(1) In the apparatus, in order to improve the detection sensitivity and the detection speed, the distance between the inner wall of the thin tube and the sensing portion of the pH electrode must be as short as possible, and hence the inner diameters of the thin tube and the sensing portion of the pH electrode are required to be as thin as possible. However, it is difficult to produce such a thin tube and a pH electrode. Particularly, there is a limitation in the thinness of the sensing portion of a pH electrode. When a pH sensitive field effect transistor (hereinafter, referred to as “pH-FET”) is used as a pH electrode, for example, the sensing portion practically has a diameter of about 0.5 mm. In accordance with this diameter, the inner diameter of a thin tube can be made to be about 0.6 mm. When a thin tube has a diameter smaller than this value, it is impossible to achieve the above-mentioned coupling.
(2) In a method in which a thin tube is coupled with a pH electrode, when the thin tube has an error in dimension or shape, there is a fear that the thin tube is contacted with the pH electrode so that the pH electrode is damaged or contaminated.
SUMMARY OF THE INVENTION
It is an object of the invention to achieve a measurement which is excellent in detection sensitivity and detection speed, and also a measurement which can be performed without causing a thin tube and the sensing portion of a pH electrode to be contacted with each other.
The apparatus for measuring material which induce a pH-change of substrate solution comprises: a thin-tube type solid phase comprising a thin tube, a receptor specific for the material which can induce a pH-change of substrate solution or the organism which can induce a pH-change of substrate solution being immobilized at least to an interior of said thin tube, the material or the organism being a measuring object; a measuring cell which accommodates a substrate solution containing a substrate for the material which can induce a pH-change of substrate solution or the organism which can induce a pH-change
Hosaka Hidehiro
Nakamura Michihiro
Okada Hiroyuki
Terasawa Harutoshi
Yukawa Hidenori
Navarro Mark
Nihon Kohden Corporation
Portner Ginny Allen
Sughrue & Mion, PLLC
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