Editing Biosensor (section)

===Ion channel switch===
[[File:wiki ics-a.jpg|right|thumb|130px|ICS – channel open]] [[File:wiki ics-b.jpg|right|thumb|130px|ICS – channel closed]]

The use of ion channels has been shown to offer highly sensitive detection 
of target biological molecules.<ref name=Vockenroth2005>{{cite book |vauthors=Vockenroth I, Atanasova P, Knoll W, Jenkins A, Köper I |title= IEEE Sensors, 2005 |chapter= Functional tethered bilayer membranes as a biosensor platform |pages=608–610 |year=2005 |doi= 10.1109/icsens.2005.1597772|isbn= 978-0-7803-9056-0 |s2cid= 12490715 }}</ref> By embedding the ion channels in supported or [[Model lipid bilayer|tethered bilayer membranes]] (t-BLM) attached to a gold electrode, an electrical circuit is created. Capture molecules such as antibodies can be bound to the ion channel so that the binding of the target molecule controls the ion flow through the channel. This results in a measurable change in the electrical conduction which is proportional to the concentration of the target.

An ion channel switch (ICS) biosensor can be created using gramicidin, a dimeric peptide channel, in a tethered bilayer membrane.<ref name=Cornell1997>{{cite journal |author=Cornell BA |title= A biosensor that uses ion-channel switches |journal=Nature |volume=387 |issue=6633 |pages=580–583 |year=1997 |doi=10.1038/42432 |pmid=9177344 |author2=BraachMaksvytis VLB |author3=King LG |display-authors=3 |last4=Osman |first4=P. D. J. |last5=Raguse |first5=B. |last6=Wieczorek |first6=L. |last7=Pace |first7=R. J. |bibcode = 1997Natur.387..580C |s2cid= 4348659 }}</ref> One peptide of gramicidin, with attached antibody, is mobile and one is fixed. Breaking the dimer stops the ionic current through the membrane. The magnitude of the change in electrical signal is greatly increased by separating the membrane from the metal surface using a hydrophilic spacer.

Quantitative detection of an extensive class of target species, including proteins, bacteria, drug and toxins has been demonstrated using different membrane and capture configurations.<ref name=Oh2008>{{cite journal |author=Oh S |title=Rapid detection of influenza A virus in clinical samples using an ion channel switch biosensor |journal=Biosensors & Bioelectronics |volume=23 |issue=7 |pages=1161–1165 |year=2008 |doi=10.1016/j.bios.2007.10.011 |pmid=18054481 |author2=Cornell B |author3=Smith D |display-authors=3 |last4=Higgins |first4=G. |last5=Burrell |first5=C.J. |last6=Kok |first6=T.W. }}</ref><ref name=Krishnamurthy2010>{{cite journal |vauthors=Krishnamurthy V, Monfared S, Cornell B |title= Ion Channel Biosensors Part I Construction Operation and Clinical Studies|journal=[[IEEE Transactions on Nanotechnology]] |volume=9 |issue=3 |pages=313–322  |year=2010 |doi=  10.1109/TNANO.2010.2041466|bibcode = 2010ITNan...9..313K |s2cid= 4957312}}</ref> The European research project [https://projects.leitat.org/greensense/ Greensense] develops a biosensor to perform quantitative screening of drug-of-abuse such as THC, morphine, and cocaine <ref>{{Cite web|url=https://www.greensense-project.eu/|title=Greensense Projekt: Cannabis-Tests und Drogen Screening|website=greensense-project.eu}}</ref> in saliva and urine.