Editing Biochip (section)

==Protein biochip array and other microarray technologies==
[[Microarray]]s are not limited to [[DNA]] analysis; [[protein microarray]]s, [[antibody microarray]], [[chemical compound microarray]] can also be produced using biochips.  Randox Laboratories Ltd. launched Evidence, the first protein Biochip Array Technology analyzer in 2003.  In protein Biochip Array Technology, the biochip replaces the [[ELISA]] plate or [[cuvette]] as the reaction platform.  The biochip is used to simultaneously analyze a panel of related tests in a single sample, producing a [[patient]] profile.  The patient profile can be used in disease screening, [[medical diagnosis|diagnosis]], monitoring disease progression or monitoring treatment.  Performing multiple analyses simultaneously, described as multiplexing, allows a significant reduction in processing time and the amount of patient sample required.  Biochip Array Technology is a novel application of a familiar methodology, using sandwich, competitive and antibody-capture [[immunoassay]]s. The difference from conventional immunoassays is that, the capture ligands are covalently attached to the surface of the biochip in an ordered array rather than in solution.

In sandwich assays an enzyme-labelled antibody is used; in competitive assays an enzyme-labelled antigen is used.  On antibody-antigen binding a [[chemiluminescence]] reaction produces light.  Detection is by a [[charge-coupled device]] (CCD) camera.  The CCD camera is a sensitive and high-resolution sensor able to accurately detect and quantify very low levels of light.  The test regions are located using a grid pattern then the chemiluminescence signals are analysed by imaging software to rapidly and simultaneously quantify the individual analytes.

Biochips are also used in the field of [[microphysiometry]] e.g. in skin-on-a-chip<ref>Alexander, F., Eggert, S., Wiest, J.: Skin-on-a-chip: Transepithelial electrical resistance and extracellular acidification measurements through an automated air-liquid interface, Genes, 2018, 9/2, 114; {{doi|10.3390/genes9020114}}</ref> applications.

For details about other array technologies, see [[Antibody microarray]].