Microarray is defined as the collection of nucleic acid (DNA and RNA) sequences that each exceptional sequence forms a little aspect, called a ‘spot’ or ‘target’. Nucleic acids are obtained in many ways. There are different methods of nucleic acid sequences for depositing them onto microarray slides. The size of spots varies from one system to another. It is less than two hundred micrometers (200u) in diameter. There are tens of thousands of spots can be arranged in a total area of a few square centimeters.
Microarray is the method for analyzing nucleic acid fragments. Its origins found in many different disciplines and techniques. A microarray is the continued development technique of molecular biology hybridization which has many applications in daily life. It is used in the extension of fluorescence microscopy in cell biology as well as a diagnostic discipline. Different techniques are utilized to prepared miniature collections of nucleic acids on solid support.
Microarray analysis hybridization is a key method for analysis nucleic acids and describes its different applications. There are many techniques are used for analyzing a limited number of genes and samples in gene expression analysis which are include Northern blotting, reverse transcriptase polymerase chain reaction (RT-PCR) and nuclease protection assays. The labeled moiety is derived from the mRNA sample. The immobilized fractions are the best known sequences usually which are used as probes. Filter-based gene expression analysis has enabled us simultaneous determination of expression levels of thousands of genes in one experiment. These microarrays have been generally adopted for gene expression studies (1).
Utilization of microscope slides to immobilize cells and chromosomes precedes filter-based gene expression analysis, as well as other important methods such as immunohistochemistry, immunocytochemistry and in situ hybridization. Fluorescent in situ hybridization (FISH) has enabled us for the detection of nucleic acids within cells and chromosomes. It has been found useful in gene expression and genomic analysis.
Different methods of analysis are applied which made to analyze nucleic acid sequences to a glass support. It is used to purify nucleic acid into a slide surface (2). Photolithography technique is applied in this method. These different methods are used to support the microarray analysis experiment by using microscope slides instead of membrane filters.
In 1995 and 1996, the first papers in which the term ‘microarray’ was used. Its current meaning were published by the laboratory of Pat Brown at Stanford University (3). Its technique is fast approved in world. This technique is illustrated by the publication in 2001 of over 900 papers which are used in microarray technique. Microarray has many applications which have many used in daily life. These are used in toxicology, evolution biology, drug designing and production, diseases characterization, diagnostics, forensic etc.