Herein we demonstrate the first example of oligonucleotidetemplated reaction (OTR) performed on paper, using lateral flow to capture and concentrate specific nucleic acid biomarkers on a test line. Quantitative analysis, using a low-cost benchtop fluorescence reader showed very high specificity down to the single nucleotide level and proved sensitive enough for amplification-free, on-chip, detection of endogenous concentrations of miR-150-5p, a recently identified predictive blood biomarker for preterm birth. † Electronic supplementary information (ESI) available: Including experimental information, PNA synthesis, coumarin probe concentration, optimization of the LFA parameters and information on the clinical samples. See Scheme 1 Schematic of the OTR-based lateral flow assay. Biotinylated PNA thiols (capture probe, green) are immobilised on a streptavidin test line (red) on a paper strip (panel 2). A mixture of PNA coumarin (sensing probe, red) and miRNA target (blue) is then added to the sample loading pad (dark grey, panel 1). Upon wicking, the miRNA of interest is retained on the test line via hybridisation to the capture thiol probe, whilst also hybridising to the sensing probe (panel 3). The excess of sensing probe and all non-complementary miRNAs are then eluted off. Fluorescence, resulting from the product of the Michael addition OTR, is then measured using either a benchtop reader or a fluorescence scanner (panel 4). Fig. 1Fluorescence scanned images (top) and traces (bottom) of LFA strips for OTR in the presence (blue, (+) DNA) and absence (green, (À) DNA) of 0.5 mM miR-150-5p DNA, and a blank strip with only buffer added (orange, Blank). The dark spot on the (À) DNA sample loading pad is background fluorescence from the excess of PNA coumarin which remains adsorbed to the paper unless hybridized to a complementary DNA. CommunicationChemComm

Correction for ‘Oligonucleotide-templated lateral flow assays for amplification-free sensing of circulating microRNAs’ by Suraj Pavagada et al., Chem. Commun., 2019, 55, 12451–12454.

The exponential improvements made in DNA sequencing technologies, together with the rapidly declining associated costs, has increasingly led to the expansion of the field of personalised genomic medicine. Changes in the sequence or copy number of specific deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) molecules represent key signatures for the diagnosis, prognosis, classification and monitoring of a broad range of pathologies, most notably cancer. Technologies that can detect these changes require analytical tools that can detect DNA or RNA with high sensitivity and high specificity. Sensing based on bio-orthogonal oligonucleotide-templated reactions (OTRs) has been recognised as an elegant strategy that satisfies these criteria and was successfully used for the quantitative detection of nucleic acids both in vitro and in vivo. Herein, we will focus on recent efforts to implement bio-orthogonal OTRs into clinically useful biosensors using probes immobilised on or embedded in customised materials and platforms.