title: Cavity-Enhanced Immunoassay Measurements in Microtiter Plates Using BBCEAS.
abstract: We report on the first detailed use of broadband cavity enhanced absorption spectroscopy (BBCEAS) as a detection system for immunoassay. A vertical R ≥ 0.99 optical cavity was integrated with a motorized XY stage, which functioned as a receptacle for 96-well microtiter plates. The custom-built cavity enhanced microplate reader was used to make measurements on a commercially available osteocalcin sandwich ELISA kit. A 30-fold increase in path length was obtained with a minimum detectable change in the absorption coefficient, αmin(t), of 5.3 × 10(-5) cm(-1) Hz(-1/2). This corresponded to a 39-fold increase in the sensitivity of measurement when directly compared to measurements in a conventional microplate reader. Separate measurements of a standard STREP-HRP colorimetric reaction in microtiter plates of differing optical quality produced an increase in sensitivity of up to 115-fold compared to a conventional microplate reader. The sensitivity of the developed setup compared favorably with previous liquid-phase cavity enhanced studies and approaches the sensitivity of typical fluorometric ELISAs. It could benefit any biochemical test which uses single pass absorption as a detection method, through either the label free detection of biologically important molecules at lower concentrations or the reduction in the amount of expensive biochemicals needed for a particular test, leading to cheaper tests.
authors.affiliation: School of Science and Engineering, Teesside University , Borough Road, Middlesbrough, TS1 3BA, United Kingdom.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Bajuszova
authors.affiliation: School of Science and Engineering, Teesside University , Borough Road, Middlesbrough, TS1 3BA, United Kingdom.
authors.forename: Zulfiqur
authors.initials: Z
authors.lastname: Ali
authors.affiliation: School of Science and Engineering, Teesside University , Borough Road, Middlesbrough, TS1 3BA, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Scott
authors.affiliation: School of Science and Engineering, Teesside University , Borough Road, Middlesbrough, TS1 3BA, United Kingdom.
authors.forename: L Nitin
authors.initials: LN
authors.lastname: Seetohul
authors.affiliation: School of Science and Engineering, Teesside University , Borough Road, Middlesbrough, TS1 3BA, United Kingdom.
authors.forename: Meez
authors.initials: M
authors.lastname: Islam
mesh_terms: D000906:Antibodies / Q000276:immunology; D003124:Colorimetry; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D057230:Limit of Detection; D015675:Osteocalcin / Q000032:analysis* / Q000276:immunology
chemical_list: D000906:Antibodies; D015675:Osteocalcin