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SERS-active metal-dielectric nanostructures integrated in microfluidic devices for label-free quantitative detection of miRNA

Abstract

In this work, SERS-based microfluidic PDMS chips integrating silver-coated porous silicon membranes were used for the detection and quantitation of microRNAs (miRNAs), which consist of short regulatory non-coding RNA sequences typically over- or under-expressed in connection with several diseases such as oncogenesis. In detail, the metal-dielectric nanostructures, which provide noticeable Raman enhancements, were functionalized according to a biological protocol, adapted and optimized from an enzyme-linked immunosorbent assay (ELISA), for the detection of miR-222. Two set of experiments, based on different detection approaches were designed and performed, yielding a critical comparison. In the first one, the labelled target miRNA is revealed through the hybridization to a complementary thiolated DNA probe, immobilized on the silver nanoparticles. In the second one, the probe is halved in shorter strands (half1 and half2) that interact with the complementary miRNA in two steps of hybridization. Such approach, taking advantage of the Raman labelling of half2, provides a label-free analysis of the target. After a suitable optimisation of the procedures, two calibration curves allowing quantitative measurements were obtained and compared on the basis of the SERS maps acquired on the samples loaded with several miRNA concentrations. The selectivity of the two-step assay was confirmed by the detection of target miR-222 mixed with different synthetic oligos, simulating the hybridization interference coming from similar sequences in real biological samples. Finally, that protocol was applied, by using the optofluidic multichamber biosensor, to the analysis of miR-222 in cellular extracts, confirming the potentialities of the SERS-microfluidic chips for early-cancer diagnosis.

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Publication details

The article was accepted on 04 May 2017 and first published on 09 May 2017


Article type: Paper
DOI: 10.1039/C7FD00140A
Citation: Faraday Discuss., 2017, Accepted Manuscript
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    SERS-active metal-dielectric nanostructures integrated in microfluidic devices for label-free quantitative detection of miRNA

    C. Novara, A. Chiadò, N. Paccotti, S. Catuogno, C. L. Esposito, G. Condorelli, V. de Franciscis, F. Geobaldo, P. Rivolo and F. Giorgis, Faraday Discuss., 2017, Accepted Manuscript , DOI: 10.1039/C7FD00140A

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