Editing Assay

{{Short description|Measure the amount of a target entity}}
{{About|assays in biology|assays of metals|metallurgical assay|the French commune|Assay, Indre-et-Loire}}
{{More citations needed|date=August 2016}}

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 a target entity. The measured entity is often called the '''analyte''', the '''measurand''', or the '''target''' of the assay. The analyte can be a [[drug]], [[Biochemistry|biochemical substance]], [[chemical element]] or [[chemical compound|compound]], or [[Cell (biology)|cell]] in an [[organism]] or organic [[Sample (material)|sample]].<ref>{{cite book|title=The American heritage dictionary of the English language|date=2006|publisher=Houghton Mifflin|location=Boston, MA|isbn=9780618701735|edition=4th}}</ref><ref>{{cite book|last1=Abate|first1=Frank|editor1-last=J. Jewell|editor1-first=Elizabeth|title=The new Oxford American dictionary|date=2001|publisher=Oxford University Press|location=Oxford|isbn=9780195112276|edition=2nd|url-access=registration|url=https://archive.org/details/newoxfordamerica0000unse}}</ref> An assay usually aims to measure an analyte's [[Intensive and extensive properties|intensive property]] and express it in the relevant [[Unit of measurement|measurement unit]] (e.g. [[molarity]], [[density]], functional activity in enzyme international units, degree of effect in comparison to a standard, etc.).

If the assay involves [[exogenous]] reactants (the [[reagent]]s), then their quantities are kept fixed (or in excess) so that the quantity and quality of the target are the only limiting factors. The difference in the assay outcome is used to [[Deductive reasoning|deduce]] the unknown quality or quantity of the target in question. Some assays (e.g., biochemical assays) may be similar to [[Analytical chemistry|chemical analysis]] and [[titration]]. However, assays typically involve [[Organic matter|biological material]] or phenomena that are intrinsically more complex in composition or behavior, or both. Thus, reading of an assay may be [[Signal-to-noise ratio|noisy]] and involve greater difficulties in interpretation than an accurate chemical titration. On the other hand, older generation qualitative assays, especially [[bioassay]]s, may be much more gross and less quantitative (e.g., counting death or dysfunction of an organism or cells in a population, or some descriptive change in some body part of a group of animals).

Assays have become a routine part of modern [[Health technology|medical]], [[Environmental technology|environmental]], [[Pharmaceutics|pharmaceutical]], and [[Forensic science|forensic technology]]. Other businesses may also employ them at the [[Industrial technology|industrial]], curbside, or field levels.  Assays in high commercial demand have been well investigated in [[research and development]] sectors of professional industries. They have also undergone generations of development and sophistication. In some cases, they are protected by intellectual property regulations such as [[patent]]s granted for inventions. Such industrial-scale assays are often performed in well-equipped [[Laboratory|laboratories]] and with automated organization of the procedure, from ordering an assay to pre-analytic sample processing (sample collection, necessary manipulations e.g. [[Centrifuge|spinning for separation]], [[sample_(material)#Aliquot_part|aliquoting]] if necessary, storage, retrieval, [[Pipette|pipetting]], [[Suction|aspiration]], etc.). Analytes are generally tested in high-[[throughput]] [[autoanalyzer]]s, and the results are verified and automatically returned to ordering service providers and [[End user|end-users]]. These are made possible through the use of an advanced [[laboratory informatics system]] that [[Interface (computing)|interfaces]] with multiple [[computer terminal]]s with end-users, central [[Server (computing)|servers]], the physical autoanalyzer instruments, and other automata.{{Clarify|reason=I assume "automata" doesn't mean "robots" in this context, so what does it mean?|date=October 2021}}

==Etymology==
According to Etymology Online,<ref>{{cite web |url= http://www.etymonline.com/index.php?term=assay|title=Online Etymology Dictionary - Assay |author=<!--Staff writer(s); no by-line.--> |date= 2016|website= etymonline|publisher=Douglas Harper |access-date= 13 Aug 2016}}</ref> the verb ''assay'' means "to try, endeavor, strive, test the quality of"; from Anglo-French ''assaier'', from ''assai'' (noun), from Old French ''essai'', "trial". Thus the noun ''assay'' means "trial, test of quality, test of character" (from mid-14th century), from Anglo-French ''assai''; and its meaning "analysis" is from the late 14th century.

For [[Metallurgical assay|assay of currency coins]] this literally meant analysis of the purity of the gold or silver (or whatever the precious component) that represented the true value of the coin. This might have translated later (possibly after the 14th century) into a broader usage of "analysis",{{citation needed|date=August 2016}} e.g., in pharmacology, analysis for an important component of a target inside a mixture—such as the [[active ingredient]] of a drug inside the inert [[excipient]]s in a formulation that previously was measured only grossly by its observable action on an organism (e.g., a lethal dose or inhibitory dose).

==General steps==
An assay (analysis) is never an isolated process, as it must be accompanied with pre- and post-analytic procedures. Both the communication order (the request to perform an assay plus related information) ''and'' the handling of the specimen itself (the collecting, documenting, transporting, and processing done before beginning the assay) are pre-analytic steps. Similarly, after the assay is completed the results must be documented, verified and communicated—the post-analytic steps. As with any multi-step [[information]] handling and [[Information transmission|transmission]] system, the variation and errors in reporting final results entail not only  those intrinsic to the assay itself but also those occurring in the pre-analytic and post-analytic procedures.

While the analytic steps of the assay itself get much attention,<ref>{{cite journal|last1=Bonini|first1=P|last2=Plebani|first2=M|last3=Ceriotti|first3=F|last4=Rubboli|first4=F|title=Errors in laboratory medicine.|journal=Clinical Chemistry|date=May 2002|volume=48|issue=5|pages=691–8|doi=10.1093/clinchem/48.5.691|pmid=11978595|doi-access=free}}</ref> it is those that get less attention of the chain of users—the pre-analytic and post-analytic procedures—that typically accumulate the most errors; e.g., pre-analytic steps in medical laboratory assays may contribute 32–75% of all lab errors.<ref>{{cite journal|last1=Hammerling|first1=Julie A.|title=A Review of Medical Errors in Laboratory Diagnostics and Where We Are Today: Table 1|journal=Laboratory Medicine|date=1 February 2012|volume=43|issue=2|pages=41–44|doi=10.1309/LM6ER9WJR1IHQAUY|doi-access=free}}</ref>

Assays can be very diverse, but generally involve the following general steps: 
# '''Sample processing and manipulation''' in order to selectively present the target in a discernible or measurable form to a discrimination/identification/detection system. It might involve a simple centrifugal separation or washing or filtration or capture by some form of selective binding or it may even involve modifying the target e.g. epitope retrieval in immunological assays or cutting down the target into pieces e.g. in [[Mass Spectrometry]]. Generally there are multiple separate steps done before an assay and are called preanalytic processing. But some of the manipulations may be inseparable part of the assay itself and will not thus be considered pre-analytic.
# '''Target-specific discrimination/identification principle''': to discriminate from background (noise) of similar components and specifically identify a particular target component ("analyte") in a biological material by its specific attributes. (e.g. in a [[Polymerase chain reaction|PCR]] assay a specific oligonucleotide primer identifies the target by [[base pairing]] based on the specific nucleotide sequence unique to the target).
# '''Signal (or target) amplification system''': The presence and quantity of that analyte is converted into a detectable signal generally involving some method of signal amplification, so that it can be easily discriminated from noise and measured - e.g. in a [[Polymerase chain reaction|PCR]] assay among a mixture of DNA sequences only the specific target is amplified into millions of copies by a [[DNA polymerase]] enzyme so that it can be discerned as a more prominent component compared to any other potential components. Sometimes the concentration of the analyte is too large and in that case the assay may involve sample dilution or some sort of signal diminution system which is a negative amplification.
# '''Signal detection (and interpretation) system''': A system of deciphering the amplified signal into an interpretable output that can be quantitative or qualitative. It can be visual or manual very crude methods or can be very sophisticated electronic digital or analog detectors.
#'''Signal enhancement and noise filtering''' may be done at any or all of the steps above. Since the more downstream a step/process during an assay, the higher the chance of carrying over noise from the previous process and amplifying it, multiple steps in a sophisticated assay might involve various means of signal-specific sharpening/enhancement arrangements and noise reduction or filtering arrangements. These may simply be in the form of a narrow [[band-pass]] optical filter, or a blocking reagent in a binding reaction that prevents nonspecific binding or a [[quencher|quenching]] reagent in a fluorescence detection system that prevents "autofluorescence" of background objects. {{citation needed|date=September 2013}}

==Assay types based on the nature of the assay process==
===Time and number of measurements taken===
Depending on whether an assay just looks at a single time point or timed readings taken at multiple time points, an assay may be:
#An '''end point assay''', in which a single measurement is performed after a fixed incubation period; or
#A '''kinetic assay''', in which measurements are performed multiple times over a fixed time interval. Kinetic assay results may be visualized numerically (for example, as a slope parameter representing the rate of signal change over time), or graphically (for example, as a plot of the signal measured at each time point). For kinetic assays, both the magnitude and shape of the measured response over time provide important information.
#A '''high throughput assay''' can be either an endpoint or a kinetic assay usually done on an automated platform in 96-, 384- or 1536-well microplate formats ('''High Throughput Screening'''). Such assays are able to test large number of compounds or analytes or make functional biological readouts in response to a stimuli and/or compounds being tested.<ref>{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK343428/ |title=Assay Guidance Manual [Internet] |last1=Sittampalam |first1= GS|date=2004 |website=ncbi.nlm.com |publisher=Eli Lilly & Company and the [[National Center for Advancing Translational Sciences]] |access-date= 12 Aug 2016}}</ref>

===Number of analytes detected===
Depending on how many targets or analytes are being measured:
#Usual assays are simple or ''single target assays'' which is usually the default unless it is called multiplex.
#[[Multiplex assay]]s are used to simultaneously measure the presence, concentration, activity, or quality of multiple analytes in a single test. The advent of ''multiplexing'' enabled rapid, efficient sample testing in many fields, including immunology, cytochemistry, genetics/genomics, pharmacokinetics, and toxicology.<ref>{{cite web |url=http://www.biotek.com/resources/articles/multiplexed-assays-life-sciences.html |title=Multiplexed Assays in the Life Sciences |last1= Banks|first1= Peter |date=7 Jun 2010 |website= biotek.com|publisher=[[BioTek]] Instruments Inc |access-date= 13 Aug 2016}}</ref>

===Result type===
Depending on the quality of the result produced, assays may be classified into:
# '''Qualitative assays''', i.e. assays which generally give just a pass or fail, or positive or negative or some such sort of only small number of qualitative gradation rather than an exact quantity.
#'''Semi-quantitative assays''', i.e. assays that give the read-out in an approximate fashion rather than an exact number for the quantity of the substance. Generally they have a few more gradations than just two outcomes, positive or negative, e.g. scoring on a scale of 1+ to 4+ as used for blood grouping tests based on RBC [[Agglutination (biology)|agglutination]] in response to grouping reagents (antibody against blood group antigens).
# '''Quantitative assays''', i.e. assays that give accurate and exact numeric quantitative measure of the amount of a substance in a sample. An example of such an assay used in coagulation testing laboratories for the most common inherited bleeding disease - [[Von Willebrand disease]] is [[Von Willebrand Factor|VWF]] antigen assay where the amount of VWF present in a blood sample is measured by an immunoassay.
# '''Functional assays''', i.e. an assay that tries to quantify functioning of an active substance rather than just its quantity. The functional counterpart of the VWF antigen assay is [[Ristocetin]] Cofactor assay, which measures the functional activity of the VWF present in a patient's plasma by adding exogenous [[Formaldehyde#Tissue fixative and embalming agent|formalin-fixed]] [[platelet]]s and gradually increasing quantities of drug named ristocetin while measuring agglutination of the fixed platelets. A similar assay but used for a different purpose is called [[Ristocetin Induced Platelet Aggregation]] or RIPA, which tests response of endogenous live platelets from a patient in response to Ristocetin (exogenous) & VWF (usually endogenous).

===Sample type and method===
Depending on the general substrate on which the assay principle is applied:
#'''Bioassay''': when the response is biological activity of live objects. Examples include
##''in vivo'', whole organism (e.g. mouse or other subject injected with a drug)
##''ex vivo'' body part (e.g. leg of a frog)
##''ex vivo'' organ (e.g. heart of a dog)
##''ex vivo'' part of an organ (e.g. a segment of an intestine).
##tissue (e.g. limulus lysate)
##cell (e.g. platelets)
#'''[[Ligand binding assay]]''' when a ligand (usually a small molecule) binds a receptor (usually a large protein).
#'''[[Immunoassay]]''' when the response is an antigen antibody binding type reaction.

===Signal amplification===
Depending on the nature of the signal amplification system assays may be of numerous types, to name a few:
#'''[[Enzyme assay]]''': Enzymes may be tested by their highly repeating activity on a large number of substrates when loss of a substrate or the making of a product may have a measurable attribute like color or [[absorbance]] at a particular wavelength or light or [[Electrochemiluminescence]] or electrical/redox activity.
#Light detection systems that may use amplification e.g. by a [[photodiode]] or a [[photomultiplier tube]] or a cooled [[charge-coupled device]].
#'''[[Radioisotope]]''' labeled substrates as used in [[radioimmunoassay]]s and equilibrium dialysis assays and can be detected by the amplification in [[Gamma counter]]s or [[X-ray plate]]s, or [[Photostimulated luminescence|phosphorimager]]
#'''[[Polymerase Chain Reaction]]''' Assays that amplify a DNA (or RNA) target rather than the signal
#'''Combination Methods''' Assays may utilize a combination of the above and other amplification methods to improve sensitivity. e.g. [[ELISA|Enzyme-linked immunoassay]] or EIA, [[enzyme linked immunosorbent assay]].

===Detection method or technology===
Depending on the nature of the Detection system assays can be based on:
#'''Colony forming''' or [[virtual colony count]]: e.g. by multiplying bacteria or proliferating cells.
#'''[[Photometry (optics)|Photometry]]''' / '''[[spectrophotometry]]''' When the absorbance of a specific wavelength of light while passing through a fixed path-length through a cuvette of liquid test sample is measured and the absorbance is compared with a blank and standards with graded amounts of the target compound. If the emitted light is of a specific visible wavelength it may be called '''[[colorimetry]]''', or it may involve specific wavelength of light e.g. by use of [[laser]] and emission of [[fluorescent]] signals of another specific wavelength which is detected via very specific wavelength optical filters.
#'''[[Transmittance]]''' of light may be used to measure e.g. clearing of opacity of a liquid created by suspended particles due to decrease in number of clumps during a platelet [[Agglutination (biology)|agglutination]] reaction.
#'''[[Turbidimetry]]''' when the opacity of straight-transmitted light passing through a liquid sample is measured by detectors placed straight across the light source.
#'''[[Nephelometry]]''' where a measurement of the amount of light scattering that occurs when a beam of light is passed through the solution is used to determine size and/or concentration and/or size distribution of particles in the sample.<ref>{{cite web |url= http://medical-dictionary.thefreedictionary.com/nephelometry|title=Nephelometry |date=2016 |website=The Free Dictionary |publisher=Farlex |access-date=9 September 2016 }}</ref>
#'''[[Reflectometry]]''' When color of light reflected from a (usually dry) sample or reactant is assessed e.g. the automated readings of the strip urine dipstick assays.
#Viscoelastic measurements e.g. viscometry, elastography (e.g. [[thromboelastography]])
#Counting assays: e.g. optic [[Flow cytometry|Flow cytometric]] cell or particle counters, or [[Coulter principle|coulter]]/impedance principle based cell counters
#Imaging assays, that involve image analysis manually or by software:
##'''[[Cytometry]]''': When the size statistics of cells is assessed by an image processor.
#Electric detection e.g. involving [[amperometry]], [[Voltammetry]], [[coulometry]] may be used directly or indirectly for many types of quantitative measurements.
#Other physical property based assays may use
##[[Osmometer]]
##[[Viscometer]]
##[[Ion Selective electrode]]s
##[[Syndromic testing]]

==Assay types based on the targets being measured==
===DNA===
Assays for studying [[Protein–protein interaction|interactions]] of [[proteins]] with [[DNA]] include:
*[[DNase footprinting assay]]
*[[Filter binding assay]]
*[[Gel shift assay]]

===Protein===
*[[Bicinchoninic acid assay]] (BCA assay)
*[[Bradford protein assay]]
*[[Lowry protein assay]]<ref>{{cite journal |vauthors=Lowry OH, Rosebrough NJ, Farr AL, Randall RJ |title=Protein measurement with the Folin phenol reagent |journal=J. Biol. Chem. |volume=193 |issue=1 |pages=265–75 |date=November 1951 |doi=10.1016/S0021-9258(19)52451-6 |pmid=14907713 |url=http://www.jbc.org/cgi/pmidlookup?view=long&pmid=14907713|doi-access=free }}</ref>
*[[Secretion assay]]

===RNA===
*[[Nuclear run-on]]
*[[Ribosome profiling]]

===Cell counting, viability, proliferation or cytotoxicity assays===
A cell-counting assay may determine the number of living cells, the number of dead cells, or the ratio of one cell type to another, such as enumerating and typing [[red blood cell|red]] versus different types of [[white blood cell|white]] blood cells. This is measured by different physical methods (light transmission, electric current change). But other methods use biochemical probing cell structure or physiology (stains). Another application is to monitor [[cell culture]] ([[Cell culture assays|assays]] of cell proliferation or [[Cytotoxicity#Measuring cytotoxicity|cytotoxicity]]).
A cytotoxicity assay measures how toxic a chemical compound is to cells.
*[[MTT assay]]
*Cell Counting Kit-8 (WST-8 based cell viability assay)
*SRB ([[Sulforhodamine B]]) assay
*CellTiter-Glo® Luminescent Cell Viability Assay 
*Cell counting instruments and methods: [[CASY cell counting technology]], [[Coulter counter]], [[Electric cell-substrate impedance sensing]]
*Cell [[viability assay]]s: [[Resazurin#Cell viability applications|resazurin method]], [[ATP test]], [[Ethidium homodimer assay]] (detect dead or dying cells), [[Bacteriological water analysis]], [[Clonogenic assay]]s, ...

===Environmental or food contaminants===
*[[Bisphenol F#Environmental contamination|Bisphenol F]]
*[[Aquatic toxicology#Aquatic toxicity tests|Aquatic toxicity tests]]

===Surfactants===
*An [[MBAS assay]] indicates [[Ion#Anions and cations|anionic]] [[surfactant]]s in water with a bluing reaction.

=== Other cell assays ===
Many cell assays have been developed to assess specific parameters or response of cells ([[biomarker]]s, cell physiology). [[Cell biology#Techniques|Techniques used to study cells]] include :
*reporter assays using i.e. [[Luciferase]], calcium signaling assays using [[Coelenterazine]], [[Carboxyfluorescein succinimidyl ester|CFSE]] or [[Calcein]]
*[[Immunostaining]] of cells on slides by [[Microscopy]] ([[Immunohistochemical staining|ImmunoHistoChemistry or Fluorescence]]), on [[microplate]]s by [[Photometry (optics)|photometry]] including the [[ELISpot]] (and its variant [[ELISpot|FluoroSpot]]) to enumerate B-Cells or antigen-specific cells, in solution by [[Flow cytometry]]
*[[Molecular biology]] techniques such as [[DNA microarray]]s, [[in situ hybridization]], combined to [[Polymerase chain reaction|PCR]], [[Computational genomics]], and [[Transfection]]; [[Cell fractionation]] or [[Immunoprecipitation]]
*[[Migration assay]]s, [[Chemotaxis assay]]
*[[Secretion assay]]s
*[[Apoptosis]] assays such as the [[DNA laddering]] assay, the [[Nicoletti assay]], [[caspase]] activity assays, and [[Annexin V]] staining
*[[Chemosensitivity assay]] measures the number of tumor cells that are killed by a cancer drug
*[[Tetramer assay]] detect the presence of antigen specific T-cells
*[[Gentamicin protection assay]] or survival assay or invasion assay to assess ability of pathogens (bacteria) to invade eukaryotic cells
* [[Metastasis Assay]]
* [[Enhancer-FACS-seq]], the technique using a cell sorting process before DNA sequencing

===Petrochemistry===
*[[Crude oil assay]]

===Virology===
The [[HPCE-based viral titer assay]] uses a proprietary, high-performance [[capillary electrophoresis]] system to determine [[baculovirus]] [[titer]].

The [[Trofile assay]] is used to determine [[HIV tropism]].

The viral [[plaque assay]] is to calculate the number of [[virus]]es present in a sample. In this technique the number of [[viral plaque]]s formed by a viral inoculum is counted, from which the actual virus concentration can be determined.

===Cellular secretions===
A wide range of cellular secretions (say, a specific [[antibody]] or [[cytokine]]) can be detected using the [[ELISA]] technique.  The number of cells which secrete those particular substances can be determined using a related technique, the [[ELISPOT]] assay.

===Drugs===
*[[Drug test|Testing for Illegal Drugs]]
*[[Schild regression#Radioligand binding assays|Radioligand binding assay]]

==Quality==
When multiple assays measure the same target their results and utility may or may not be comparable depending on the natures of the assay and their methodology, reliability etc. Such comparisons are possible through study of general quality attributes of the assays e.g. principles of measurement (including identification, amplification and detection), dynamic range of detection (usually the range of linearity of the ''standard curve''), [[analytic sensitivity]], [[functional sensitivity]], [[analytic specificity]], [[Positive predictive value|positive]], [[negative predictive value]]s, turn around time i.e. time taken to finish a whole cycle from the preanalytic steps till the end of the last post analytic step (report dispatch/transmission), [[throughput]] i.e. number of assays done per unit time (usually expressed as per hour) etc. Organizations or laboratories that perform Assays for professional purposes e.g. medical diagnosis and prognostics, environmental analysis, forensic proceeding, pharmaceutical research and development must undergo well regulated [[quality assurance]] procedures including [[method validation]], regular [[calibration]], [[analytical quality control]], [[proficiency testing]], test [[accreditation]], test [[licensing]] and must document appropriate certifications from the relevant regulating bodies in order to establish the reliability of their assays, especially to remain legally acceptable and accountable for the quality of the assay results and also to convince customers to use their assay commercially/professionally.

==List of BioAssay databases ==

=== Bioactivity databases ===

Bioactivity databases correlate structures or other chemical information to bioactivity results taken from [[bioassays]] in literature, patents, and screening programs.

<!-- Do not add new entries without at least one reliable secondary third-party source that supports the addition, provided as an inline citation by clicking the "Cite" button of the editor. Alternatively, link to an existing Wikipedia article. Additions that depend entirely on the official web presence of the product will be removed, as Wikipedia is an encyclopedia, not a directory. -->
{| class="wikitable sortable"
|-
! Name
! Developer(s)
! Initial release
|-
| [[ScrubChem]]
| [[Jason Bret Harris]]
| 2016<ref>{{cite book |last1=Harris |first1=JB |chapter=Post-processing of Large Bioactivity Data |title=Bioinformatics and Drug Discovery |series=Methods in Molecular Biology |date=2019 |volume=1939 |pages=37–47 |doi=10.1007/978-1-4939-9089-4_3 |pmid=30848455 |isbn=978-1-4939-9088-7 |s2cid=73493315 }}</ref>
|-
|-
| [[PubChem|PubChem-BioAssay]]
| [[NIH]] 
| 2004<ref name="Wang et al 2017">{{cite journal |last1=Wang |first1=Yanli |last2=Bryant |first2=Stephen H. |last3=Cheng |first3=Tiejun |last4=Wang |first4=Jiyao |last5=Gindulyte |first5=Asta |last6=Shoemaker |first6=Benjamin A. |last7=Thiessen |first7=Paul A. |last8=He |first8=Siqian |last9=Zhang |first9=Jian |title=PubChem BioAssay: 2017 update |journal=Nucleic Acids Research |date=4 January 2017 |volume=45 |issue=D1 |pages=D955–D963 |doi=10.1093/nar/gkw1118 |pmid=27899599 |pmc=5210581 }}</ref>
|-
| [[ChEMBL]]
| [[EMBL-EBI]]
| 2009
|-
|}

=== Protocol databases ===

Protocol databases correlate results from [[bioassays]] to their metadata about experimental conditions and protocol designs.

<!-- Do not add new entries without at least one reliable secondary third-party source that supports the addition, provided as an inline citation by clicking the "Cite" button of the editor. Alternatively, link to an existing Wikipedia article. Additions that depend entirely on the official web presence of the product will be removed, as Wikipedia is an encyclopedia, not a directory. -->
{| class="wikitable sortable"
|-
! Name
! Developer(s)
! Initial release
|-
| [[BioMetaData]] or [[BioAssay Express]]
| [[Collaborative Drug Discovery]]
| 2016<ref>{{cite web |url=https://assay.biometadata.com/ |title=Home |website=assay.biometadata.com}}</ref>
|-
|-
| [[PubChem|PubChem-BioAssay]]
| [[NIH]] 
| 2004<ref name="Wang et al 2017"/>
|-
|}

==See also==
*[[Analytical chemistry]]
*[[MELISA]]
*[[Multiplex (assay)]]
*[[Pharmaceutical chemistry]]
*[[Titration]]

==References==
{{Reflist}}

==External links==
*{{Cite EB1911|wstitle=Assaying|volume=2|pages=776–778|first=Andrew Alexander|last=Blair}} This includes a detailed, technical explanation of contemporaneous metallic ore assay techniques.
*{{Wiktionary-inline|assay}}
{{Use dmy dates|date=April 2017}}
{{Authority control}}

[[Category:Biochemistry]]
[[Category:Laboratory techniques]]
[[Category:Titration]]