title: Sub-nanomolar detection of thrombin activity on a microfluidic chip.
abstract: Bioluminescence resonance energy transfer (BRET) is a form of Förster resonance energy transfer. BRET has been shown to support lower limits of detection than fluorescence resonance energy transfer (FRET) but, unlike FRET, has not been widely implemented on microfluidic devices for bioanalytical sensing. We recently reported a microscope-based microfluidic system for BRET-based biosensing, using a hybrid, high quantum-efficiency, form of BRET chemistry. This paper reports the first optical fiber-based system for BRET detection on a microfluidic chip, capable of quantifying photon emissions from the low quantum-efficiency BRET(2) system. We investigated the effects of varying core diameter and numerical aperture of optical fibers, as well as varying microfluidic channel design and measurement conditions. We optimized the set-up in order to maximize photon counts and minimize the response time. The optimized conditions supported measurement of thrombin activity, with a limit of detection of 20 pM, which is lower than the microscope-based system and more than 20 times lower than concentrations reported to occur in plasma clots.
authors.affiliation: Microfluidics Laboratory , CSIRO Materials Science and Engineering and CSIRO Food Futures Flagship, Clayton South MDC, Victoria 3169, Australia.
authors.forename: Nam Cao Hoai
authors.initials: NC
authors.lastname: Le
authors.affiliation: Microfluidics Laboratory , CSIRO Materials Science and Engineering and CSIRO Food Futures Flagship, Clayton South MDC, Victoria 3169, Australia.
authors.forename: Murat
authors.initials: M
authors.lastname: Gel
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: CSIRO Ecosystem Sciences and CSIRO Food Futures Flagship , GPO Box 1700, Canberra ACT 2601, Australia.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: CSIRO Ecosystem Sciences and CSIRO Food Futures Flagship , GPO Box 1700, Canberra ACT 2601, Australia.
authors.forename: Helen
authors.initials: H
authors.lastname: Dacres
authors.affiliation: CSIRO Ecosystem Sciences and CSIRO Food Futures Flagship , GPO Box 1700, Canberra ACT 2601, Australia.
authors.forename: Alisha
authors.initials: A
authors.lastname: Anderson
authors.affiliation: CSIRO Ecosystem Sciences and CSIRO Food Futures Flagship , GPO Box 1700, Canberra ACT 2601, Australia.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Trowell