Microarray
Introduction
A microarray is a high-throughput technology used in molecular biology and in medicine. It consists of an arrayed series of thousands of microscopic spots of DNA, RNA, or protein molecules attached to a solid surface. Scientists use microarrays to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome.
History and Development
The development of microarrays has its roots in early DNA sequencing technology. The first microarrays were created and used in the late 1980s and early 1990s. The technology has since evolved, with improvements in the manufacturing process, the quality of the arrayed molecules, and the detection methods used.
Types of Microarrays
There are several types of microarrays, including DNA microarrays, RNA microarrays, and protein microarrays. Each type has its specific applications and methods of preparation.
DNA Microarrays
DNA microarrays, also known as DNA chips or biochips, are used to measure levels of gene expression. These arrays consist of DNA molecules attached to a solid surface, such as a glass slide.
RNA Microarrays
RNA microarrays, also known as gene expression microarrays, are used to measure the expression levels of thousands of genes at once. This can provide valuable information about which genes are turned on or off in particular cells or under specific conditions.
Protein Microarrays
Protein microarrays, also known as protein chips, are used to track the interactions and activities of proteins, and to determine their function. Protein microarrays are more complex than DNA microarrays because proteins have multiple functions and can interact with each other in many different ways.
Microarray Technology
Microarray technology involves several steps, including the preparation of the array, the hybridization of the array with a sample, the scanning of the array to detect the hybridized sample, and the analysis of the data.
Preparation of the Array
The preparation of the array involves attaching DNA, RNA, or protein molecules to a solid surface. This is usually done by printing the molecules onto the surface using a robotic device.
Hybridization
Hybridization involves incubating the array with a sample, such as a DNA or RNA sample, that has been labeled with a fluorescent dye. The sample will bind, or hybridize, to the complementary DNA, RNA, or protein molecules on the array.
Scanning and Data Analysis
After hybridization, the array is scanned to detect the fluorescently labeled sample. The amount of fluorescence at each spot on the array corresponds to the amount of sample that has hybridized to the arrayed molecule at that spot. This data is then analyzed to determine the relative amounts of each molecule in the sample.
Applications
Microarrays have a wide range of applications in biology and medicine. They are used in gene expression profiling, to study genetic variation, and to diagnose disease. They are also used in drug discovery and development, to identify new drug targets and to test the effects of drugs on gene expression.
Future Directions
The future of microarray technology is likely to involve improvements in the quality and specificity of the arrayed molecules, the sensitivity of the detection methods, and the analysis of the data. There is also a trend towards miniaturization, with the development of microarrays that are smaller, more efficient, and more cost-effective.