A microarray is a multiplex lab-on-a-chip. Its purpose is to simultaneously detect the expression of thousands of genes from a sample (e.g. from a tissue). It is a two-dimensional array on a solid substrate—usually a glass slide or silicon thin-film cell—that

assay An assay is an investigative (analytic) procedure in laboratory medicine, mining, pharmacology, environmental biology and molecular biology for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of ...

s (tests) large amounts of biological material using high-throughput screening miniaturized, multiplexed and parallel processing and detection methods. The concept and methodology of microarrays was first introduced and illustrated in antibody microarrays (also referred to as antibody matrix) by Tse Wen Chang in 1983 in a scientific publication and a series of patents. The " gene chip" industry started to grow significantly after the 1995 '' Science Magazine'' article by the Ron Davis and Pat Brown labs at Stanford University. With the establishment of companies, such as Affymetrix, Agilent, Applied Microarrays, Arrayjet, Illumina, and others, the technology of

DNA microarray A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface. Scientists use DNA microarrays to measure the expression levels of large numbers of genes simultaneously or to ...

s has become the most sophisticated and the most widely used, while the use of protein, peptide and carbohydrate microarrays is expanding. Types of microarrays include: *

s, such as cDNA microarrays, oligonucleotide microarrays, BAC microarrays and SNP microarrays * MMChips, for surveillance of microRNA populations * Protein microarrays * Peptide microarrays, for detailed analyses or optimization of

protein–protein interaction Protein–protein interactions (PPIs) are physical contacts of high specificity established between two or more protein molecules as a result of biochemical events steered by interactions that include electrostatic forces, hydrogen bonding and th ...

s * Tissue microarrays * Cellular microarrays (also called transfection microarrays) * Chemical compound microarrays * Antibody microarrays * Glycan arrays (carbohydrate arrays) * Phenotype microarrays * Reverse phase protein lysate microarrays, microarrays of lysates or serum * Interferometric reflectance imaging sensor ( IRIS) People in the field of CMOS biotechnology are developing new kinds of microarrays. Once fed magnetic nanoparticles, individual cells can be moved independently and simultaneously on a microarray of magnetic coils. A microarray of

nuclear magnetic resonance Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are perturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a ...

microcoils is under development.

Fabrication and operation of microarrays

A large number of technologies underlie the microarray platform, including the material substrates, spotting of biomolecular arrays, and the microfluidic packaging of the arrays. Microarrays can be categorized by how they physically isolate each element of the array, by spotting (making small physical wells), on-chip synthesis (synthesizing the target DNA probes adhered directly on the array), or bead-based (adhering samples to barcoded beads randomly distributed across the array).

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Fabrication and operation of microarrays

See also

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