Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Reexamination Certificate
2001-06-21
2004-06-22
Forman, B J (Department: 1634)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
C435S174000, C435S283100, C435S287200, C422S068100, C422S105000, C536S023100
Reexamination Certificate
active
06753144
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a DNA microarray (DNA chip) which specifically reacts with a biochemical specimen and which is used for inspection equipment represented, for example, by a biochip to be used in order to obtain information on a structure of the specimen, especially in which several thousand to not less than ten thousand kinds of different types of DNA fragments are aligned and fixed at a high density as spots on a base plate such as a microscopic glass slide.
BACKGROUND OF THE INVENTION
The method of analyzing the genetic structure has been remarkably progressed in recent years. A large number of genetic structures represented by those of human genes have been clarified. The analysis of the genetic structure uses a DNA microarray (DNA chip) in which several thousand to not less than ten thousand kinds of different types of DNA fragments are aligned and fixed as spots on a base plate such as a microscopic glass slide.
In recent years, there is a demand for enhancing the reproducibility, the quantitative performance in the information obtained from the DNA microarray and obtaining much more information from the DNA microarray. The information obtained from respective spots needs to be correct, uniform, and complex.
Those widely used as the method of forming the spots for the production of the DNA microarray are generally based on a system such as the QUILL system, the pin & ring system, and the spring pin system in which a sample solution containing DNA fragments is supplied (stamped) onto the base plate by using a so-called pin. When any one of the foregoing methods is adopted, it is important to suppress the dispersion of the volume and the shape of each spot so that the distance between the respective spots is maintained to be constant.
On the other hand, in order to realize a higher density, it is also greatly expected to develop a new method which is excellent in productivity and in which the shape control performance for the spot is satisfactory.
The conventional method of forming the spot is based on the supply (stamping) of the sample solution onto the base plate by using the pin. Therefore, the shape of the spot is diversified, for example, due to the shape of the forward end of the pin and/or the residue of the sample solution remaining at the forward end of the pin after the supply. As shown in
FIG. 18
, spots
200
, each of which has many irregularities at the outer circumferential portion, are formed on a base plate
202
.
When unknown DNA is inspected by using a DNA microarray arranged with a large number of spots having dispersed shapes, it is apt to be difficult to recognize the fluorescence light emission from the spot with a CCD camera or the like. Therefore, the inspection accuracy may be lowered.
Further, when many irregularities exist at the outer circumferential portion, the sample solution flows through angular portions. Therefore, the sample solutions in the plurality of spots
200
may be mixed with each other.
The present invention has been made taking the foregoing problems into consideration, an object of which is to provide a DNA microarray which makes it possible to improve the inspection accuracy for genetic analyses and which makes it possible to increase the amount of information to be obtained.
Another object of the present invention is to provide a DNA microarray which makes it possible to achieve a high degree of concentration of spots and which makes it possible to perform detailed genetic analyses.
Still another object of the present invention is to provide a DNA microarray which makes it possible to recognize the degree of the reaction with respect to an amount of DNA fragments immobilized in a spot and which makes it possible to obtain an analog inspection result for a specimen, in addition to a digital inspection result to indicate whether or not the reaction occurs.
The applicable range of the present invention is not limited to the DNA microarray in which DNA fragments are aligned and immobilized as spots. The present invention is generally usable for every type of the biochip which specifically reacts with a biochemical specimen and which is used in order to obtain information on the structure of the specimen.
SUMMARY OF THE INVENTION
The present invention lies in a biochip comprising a large number of spots based on capture solutions arranged on a base plate, obtained by supplying, onto the base plate, a plurality of types of the capture solutions each of which specifically reacts with a specimen and each of which is used to obtain information on a structure of the specimen; wherein a plurality of the spots, which have different spot sizes, are formed on the base plate.
Accordingly, it is possible for the respective spots to suppress the dispersion of the ability to capture the specimen among the spots, which would be otherwise caused by the difference in amount of the capture immobilized on the spot or by the different abilities of the captures to capture the specimen. Thus, it is possible to suppress the dispersion of inspection results and the deterioration of quantitative performance, which would be otherwise caused by the difference in detection sensitivity among the spots.
That is, the spot, which corresponds to the capture with a small amount to be immobilized on the base plate or which corresponds to the capture with a low ability to capture the specimen, is increased in size, generally in diameter of a circular configuration. Accordingly, the detection sensitivity per one spot can be increased. As a result, it is possible to uniformize the detection sensitivities of all of the spots.
In another aspect, the present invention has the following feature. That is, when a plurality of the spots are formed for captures of an identical type on a single sheet of the base plate, then the plurality of the spots, which have different spot sizes on the base plate respectively, are formed for the captures of the identical type.
When the construction as described above is adopted, it is possible to recognize the degree of the reaction corresponding to the size of the spot, in addition to a digital inspection result to indicate whether or not the reaction occurs with respect to the captures of the identical type. Thus, it is possible to obtain an analog inspection result for the specimen. Of course, the analog inspection result can be theoretically obtained by detecting, in an analog manner, the amount of a probe which reacts with the capture immobilized in one spot. However, actually, such a procedure cannot be executed due to the restriction including, for example, the detection sensitivity of the detection equipment, the resolution, and the reaction efficiency. Therefore, the analog analysis can be performed by combining the plurality of spots using the plurality of spots having the different sizes of the spots on the base plate respectively for the captures of the identical type as performed in the present invention, although the detection of a each spot is performed in a digital manner.
In still another aspect, the present invention lies in a biochip comprising a large number of spots based on capture solutions arranged on a base plate, obtained by supplying, onto the base plate, a plurality of types of the capture solutions each of which specifically reacts with a specimen and each of which is used to obtain information on a structure of the specimen; wherein a plurality of the spots are formed, in which an amount of a capture per unit area immobilized in each of the spots differs.
Accordingly, it is possible for the respective spots to suppress the dispersion of the ability to capture the specimen among the spots, which would be otherwise caused by the different abilities of the captures to capture the specimen, in the same manner as in the case in which the sizes of the spots differ as described above. Thus, it is possible to suppress the dispersion of inspection results and the deterioration of quantitative performance, which would be otherwise caused by the difference in detection sensitivit
Hirota Toshikazu
Ohnishi Takao
Burr & Brown
Forman B J
NGK Insulators Ltd.
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