Issue 6, 2016

Wash-free magnetic immunoassay of the PSA cancer marker using SERS and droplet microfluidics

Abstract

We report a novel wash-free magnetic immunoassay technique for prostate-specific antigen (PSA) that uses a surface-enhanced Raman scattering (SERS)-based microdroplet sensor. The magnetic bar embedded in a droplet-based microfluidic system segregates the free and bound SERS tags by splitting the droplets into two smaller parts. The presence of PSA targets leads more SERS tags to immunocomplex in one droplet so that fewer SERS tags remain in another supernatant solution droplet. Thus, SERS signal measurement enables the quantitative evaluation of PSA markers. This approach can provide a rapid and sensitive assay that is applicable for PSA cancer markers in serum without any washing. Specifically, SERS signals were measured at 174 droplets per minute and averaged for quantitative evaluation of PSA. The limit of detection (LOD) determined by our SERS-based microdroplet sensor was estimated to be below 0.1 ng mL−1, which is significantly below the clinical cut-off value for the diagnosis of prostate cancer. In addition, because the entire assay can be carried out automatically, only a minimal amount of sample is needed. Accordingly, the approach is expected to be useful as a potential clinical tool for the early diagnosis of prostate cancer.

Graphical abstract: Wash-free magnetic immunoassay of the PSA cancer marker using SERS and droplet microfluidics

Supplementary files

Article information

Article type
Paper
Submitted
10 Oct 2015
Accepted
31 Jan 2016
First published
01 Feb 2016

Lab Chip, 2016,16, 1022-1029

Wash-free magnetic immunoassay of the PSA cancer marker using SERS and droplet microfluidics

R. Gao, Z. Cheng, A. J. deMello and J. Choo, Lab Chip, 2016, 16, 1022 DOI: 10.1039/C5LC01249J

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