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TitleMicrofluidic immunosensor for rapid and highly-sensitive salivary cortisol quantification
Author(s)Pinto, Vânia C.
Sousa, Paulo J.
Catarino, Susana Oliveira
Neves, Margarida Correia
Minas, Graça
KeywordsMicrofluidic immunosensor
Colorimetric detection
Lab-on-a-chip (LOC)
Salivary cortisol
Issue date15-Apr-2017
JournalBiosensors and Bioelectronics
CitationPinto, V., Sousa, P., Catarino, S. O., Correia-Neves, M., & Minas, G. (2017). Microfluidic immunosensor for rapid and highly-sensitive salivary cortisol quantification. Biosensors and Bioelectronics, 90, 308-313
Abstract(s)This paper presents a novel poly(dimethylsiloxane) (PDMS) microfluidic immunosensor that integrates a complementary metal-oxide-semiconductor (CMOS) optical detection system for a rapid and highly-sensitive quantification of salivary cortisol. The simple and non-invasive method of saliva sampling provides an interesting alternative to the blood, allowing a fast sampling at short intervals, relevant for many clinical diagnostic applications. The developed approach is based on the covalent immobilization of a coating antibody (Ab), a polyclonal anti-IgG, onto a treated PDMS surface. The coating Ab binds the capture Ab, an IgG specific for cortisol, allowing its correct orientation. Horseradish peroxidase (HRP)-labelled cortisol is added to compete with the cortisol in the sample, for the capture Ab binding sites. The HRP-labelled cortisol, bonded to the capture Ab, is measured through the HRP enzyme and the tetramethylbenzidine (TMB) substrate reaction. The cortisol quantification is performed by colorimetric detection of HRP-labelled cortisol, through optical absorption at 450 nm, using a CMOS silicon photodiode as the photodetector. Under the developed optimized conditions presented here, e.g., microfluidic channels geometry, immobilization method and immunoassay conditions, the immunosensor shows a linear range of detection between 0.01-20 ng/mL, a limit of detection (LOD) of 18 pg/mL and an analysis time of 35 min, featuring a great potential for point-of-care applications requiring continuous monitoring of the salivary cortisol levels during a circadian cycle.
Publisher version
AccessOpen access
Appears in Collections:DEI - Artigos em revistas internacionais
ICVS - Artigos em Revistas Internacionais com Referee

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