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Issue 21, 2017
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Differential detection photothermal spectroscopy: towards ultra-fast and sensitive label-free detection in picoliter & femtoliter droplets

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Abstract

Despite the growing importance of droplet-based microfluidics in high-throughput experimentation, few current methods allow the sensitive measurement of absorbance within rapidly moving droplets. To address this significant limitation, we herein present the application of differential detection photothermal interferometry (DDPI) for single-point absorbance quantification in pL- and fL-volume droplets. To assess the efficacy of our approach, we initially measure absorbance in 100 pL droplets at frequencies in excess of 1 kHz and determine a detection limit of 1.4 μmol L−1 for Erythrosin B (A = 3.8 × 10−4). Subsequently, we apply the method to the analysis of fL-volume droplets and droplets generated at frequencies in excess of 10 kHz. Finally, we demonstrate the utility of DDPI as a detection scheme for colorimetric assays. Specifically, we extract the Michaelis–Menten constant for the reaction of β-galactosidase and chlorophenol-red-β-D-galactopyranoside and monitor the metabolomic activity of a population of HL-60 cells at the single cell level. Results establish single-point absorbance detection as a powerful, sensitive and rapid alternative to fluorescence for a wide range of assays within segmented flows.

Graphical abstract: Differential detection photothermal spectroscopy: towards ultra-fast and sensitive label-free detection in picoliter & femtoliter droplets

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Publication details

The article was received on 03 Sep 2017, accepted on 27 Sep 2017 and first published on 02 Oct 2017


Article type: Paper
DOI: 10.1039/C7LC00946A
Citation: Lab Chip, 2017,17, 3654-3663
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    Differential detection photothermal spectroscopy: towards ultra-fast and sensitive label-free detection in picoliter & femtoliter droplets

    R. M. Maceiczyk, D. Hess, F. W. Y. Chiu, S. Stavrakis and A. J. deMello, Lab Chip, 2017, 17, 3654
    DOI: 10.1039/C7LC00946A

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