Editing Biosensor (section)

=== Biological biosensors ===
Biological biosensors, also known as [[Optogenetic methods to record cellular activity|optogenetic sensors]], often incorporate a genetically modified form of a native protein or enzyme. The protein is configured to detect a specific analyte and the ensuing signal is read by a detection instrument such as a fluorometer or luminometer. An example of a recently developed biosensor is one for detecting [[cytosol]]ic concentration of the analyte cAMP (cyclic adenosine monophosphate), a second messenger involved in cellular signaling triggered by ligands interacting with receptors on the cell membrane.<ref>{{cite journal | last1 = Fan | first1 = F. | display-authors = etal   | year = 2008 | title = Novel Genetically Encoded Biosensors Using Firefly Luciferase | journal = ACS Chem. Biol. | volume = 3 | issue = 6| pages = 346–51 | doi=10.1021/cb8000414| pmid = 18570354 }}</ref> Similar systems have been created to study cellular responses to native ligands or xenobiotics (toxins or small molecule inhibitors). Such "assays" are commonly used in drug discovery development by pharmaceutical and biotechnology companies. Most cAMP assays in current use require lysis of the cells prior to measurement of cAMP. A live-cell biosensor for cAMP can be used in non-lysed cells with the additional advantage of multiple reads to study the kinetics of receptor response.

Nanobiosensors use an immobilized bioreceptor probe that is selective for target analyte molecules. Nanomaterials are exquisitely sensitive chemical and biological sensors. Nanoscale materials demonstrate unique properties. Their large surface area to volume ratio can achieve rapid and low cost reactions, using a variety of designs.<ref>{{cite journal | last1 = Urban | first1 = Gerald A | year = 2009 | title =  Micro- and nanobiosensors—state of the art and trends| journal = Meas. Sci. Technol. | volume = 20 | issue = 1| page = 012001 | doi = 10.1088/0957-0233/20/1/012001 |bibcode = 2009MeScT..20a2001U | s2cid = 116936804 }}</ref>

<!--=== Evanescent wave-based biosensors ===-->
Other evanescent wave biosensors have been commercialised using waveguides where the propagation constant through the waveguide is changed by the absorption of molecules to the waveguide surface. One such example, [[dual polarisation interferometry]] uses a buried waveguide as a reference against which the change in propagation constant is measured. Other configurations such as the [[Mach–Zehnder]] have reference arms lithographically defined on a substrate. Higher levels of integration can be achieved using resonator geometries where the resonant frequency of a ring resonator changes when molecules are absorbed.<ref>{{cite journal | last1 = Iqbal | first1 = M. | last2 = Gleeson | first2 = M. A. | last3 = Spaugh | first3 = B. | last4 = Tybor | first4 = F. | last5 = Gunn | first5 = W. G. | last6 = Hochberg | first6 = M. | last7 = Baehr-Jones | first7 = T. | last8 = Bailey | first8 = R. C. | last9 = Gunn | first9 = L. C. | year = 2010 | title = Label-Free Biosensor Arrays Based on Silicon Ring Resonators and High-Speed Optical Scanning Instrumentation | journal = IEEE Journal of Selected Topics in Quantum Electronics | volume = 16 | issue = 3| pages = 654–661 | doi=10.1109/jstqe.2009.2032510| bibcode = 2010IJSTQ..16..654I | s2cid = 41944216 }}</ref><ref>{{cite journal|author1=J. Witzens |author2=M. Hochberg |title=Optical detection of target molecule induced aggregation of nanoparticles by means of high-Q resonators|journal=Opt. Express|volume=19|issue=8 |pages=7034–7061|year=2011|url = http://www.opticsinfobase.org/oe/fulltext.cfm?uri=oe-19-8-7034&id=211400|doi=10.1364/oe.19.007034|pmid=21503017 |bibcode = 2011OExpr..19.7034W |doi-access=free}}</ref>