Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Reexamination Certificate
2002-02-07
2003-12-09
Riley, Jezia (Department: 1637)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
C536S022100, C536S023100, C536S024300, C536S025300, C536S025320, C536S026300
Reexamination Certificate
active
06660479
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for preparing peptide nucleic acid probes by employing polymeric photoacid generator, more specifically to a process for preparing arrays of oligopeptide nucleic acid probes immobilized on a solid matrix by employing polymeric photoacid generator.
2. Description of the Related Art
Biochips, a kind of biosensor used for genomic analysis, medical diagnosis and monitoring biological processes and environment, are largely classified into DNA chip which identifies nucleotide sequences and protein chip which recognizes proteins such as pathogens, antibodies, antigens or enzymes.
The structure of DNA identified by Watson and Crick in 1953 has been a great impact on life sciences such as molecular biology, biochemistry, etc. DNA is a biopolymer with four different bases of adenine (A), cytosine (C), guanine (G), thymine (T), sugar (deoxyribose) and phosphate, to build a very stable double helix structure: the phosphate-sugar forms backbone, bases attached to the sugar are paired with complementary bases, such as A to T, and G to C, which are stabilized by hydrogen bond. The specific/complementary hydrogen bond between bases plays a very important role in drug developments such as antisense drug and gene therapy, in particular, for genetic disease, cancer and cardiac diseases.
Recently, in line with the great efforts made to identify approximately 100,000 human genes, needs for the methods for providing enormous genomic information as fast as possible for the diagnosis and prevention of genetic disease are increasing. Despite Sanger's DNA sequencing method is improved by polymerase chain reaction and automation, it still remains cumbersome and time-consuming, and requires high cost as well as highly trained personnel. Therefore, alternative method to overcome those shortfalls has been constantly deliberated in the art. By virtue of such needs, there has been a considerable progress in the fabrication and utilization techniques of DNA chips for recent several years.
In general, DNA chip is high-density micro-arrays of known oligonucleotide probes ranging from several hundred to several hundred thousands immobilized on a smaller than one square inch solid surface, such as silica, surface-derivatized glass, polypropylene or activated polyacrylamide. If the target DNA fragments are placed on DNA chip, the target DNA fragments hybridize to the probes on the chip according to the sequence complementarity. Therefore, the sequence of the target DNA can be analyzed by the presence and location of hybridized DNA detected by the optical or radiochemical method. Using the DNA chip aided method, DNA analysis system can be miniaturized such that an extremely small amount of sample DNA can be used for diagnosis, several sequences in a target DNA can be analyzed simultaneously, and thus the genetic information can be obtained in a simple, cost effective and fast manner.
The sequence analysis technique using oligonucleotide DNA chip is an innovative method since it is faster and easier to use for sequencing a target gene than the conventional Sanger's method. The Sanger's sequencing method, which requires the separation of fluorescence- or radioisotope-labeled DNA fragments by gel electrophoresis, is proven to be less satisfactory in light of time-consuming and technical difficulties. On the contrary, sequencing by hybridization (SBH) using oligonucleotide DNA chip employs a principle that by placing fluorescence- or radioisotope-labeled target gene fragments to a DNA chip with oligonucleotide probes, and then simply by washing the chip with solvent, gene fragments complementary to known oligonucleotide probes are attached by hydrogen bond.
Merryfield's synthetic method in which chemical compounds are reacted on organic solvent-resistant solid matrix and further organic reactions are carried out on the solid matrix, has been used effectively in synthesizing oligopeptide of biologically important enzymes and oligonucleotide of genes, since it is very simple and efficient in the purification of reaction products. See Fed. Proc., 24:412, 1962. A new efficient synthetic method combining the said method with combination chemistry has been used effectively for catalyst screening and also been used in drug development as well. In addition, by the combination of the synthetic method on a solid matrix and the photolithography employed in semiconductor industry, various techniques for preparing arrays of oligonucleotide probes have been developed to be used for genetic diagnosis. The said technique comprises selective activation of specific regions of surface derivatized glass to which the oligonucleotide binds chemically. To activate the specific targeted region, the light beam is applied through a transparent region of photolithographic mask made by a predetermined pattern. By controlling the mask pattern and composition of nucleic acids at each step, a specific nucleic acid can be positioned on a desired location. This technique is an ultra-fine processing technique used in semiconductor devices which makes possible several millions of probes be affixed on a fingernail-size chip.
For example, Fordor et al teaches a new direct photolysis technique, where nucleic acid or amino acid with UV-labile protecting group is attached on a solid surface, the protecting group is eliminated by exposing the selected regions of surface to light using photolithographic mask, which is subsequently reacted with a new nucleic acid or amino acid with a photo-labile protecting group, to polymerize nucleic acid or amino acid at specific location. See U.S. Pat. No. 5,445,934, which is hereby incorporated herein by reference. Since this method allows selective synthesis of oligonucleotide probes with a specific sequence/length at a specific location, it is useful in synthesizing various oligonucleotide probes with a desired sequence and length at a predetermined position. Also, since this method employs ultra-fine process used in semiconductor devices, it is extremely useful for fabricating oligonucleotide probes in high density. Fordor et al also suggested that a sequencing method using the oligonucleotide probes which is much easier and faster than Sanger's method, is useful for making high density oligonucleotide probes. However, it has revealed a shortcoming that: the removal of photo-labile protecting group is proportional to the power of a light source, which plays a detrimental role in the ultra-fine process for making high density chips.
On the other hand, photolithographic process using photoresist (hereinafter referred to as ‘PR’) which is used for micropattern formation in semiconductor industry has attracted attention as an essential technique to improve the density of DNA chip. Since the size or capacity of a semiconductor chip is depending on the spatial resolution of photolithographic process, photolithographic process has played a leading role in the semiconductor and microelectronics industry. The photolithographic process utilizes the solubility differences of PR between the light exposed region and the unexposed region. The solubility reduction in the exposed region is called as negative system and solubility increase is called as positive system, and the latter is used mostly for the production of semiconductor chips. By using above photolithographic process, more oligonucleotide probes can be arrayed on a limited area of chip.
Up to now, photolithographic process has been applied in the general PR system (U.S. Pat. No. 5,658,734) and the photoacid patterned array system (hereinafter referred to as ‘PPA’, U.S. Pat. No. 5,843,655) as well. The referenced patents are hereby incorporated herein by reference.
Photolithographic process using PR system (hereinafter referred to as ‘PR process’) has an advantage of using materials already developed or commercialized for semiconductor industry. According to the system, a pattern is formed by the light exposure and washed out to lead to standard solid-p
Kim Do-Yun
Kim Min-Hwan
Kim Young-Hee
Moon Bong-Seok
Park Jae-Chan
Knobbe Martens Olson & Bear LLP
Riley Jezia
LandOfFree
Process for preparing peptide nucleic acid probe using... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for preparing peptide nucleic acid probe using..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing peptide nucleic acid probe using... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3173346