Oligonucleotide sensor based on magnetic capture and photoligation of upconverting nanoparticles in solid surfaces

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In this work, we present a luminescence platform that can be used as point of care system for determining the presence and concentration of specific oligonucleotide sequences. This sensor exhibited a limit of detection as low as 50 fM by means of: i) the use of single-stranded DNA (ssDNA) functionalized magnetic microparticles that captured and concentrated ssDNA-upconverting nanoparticles (ssDNA-UCNPs) on a solid support, when the target sequence (miR-21-5p DNA-analogue) was in the sample, and ii) a photoligation reaction that covalently linked the ssDNA-UCNPs and the ssDNA magnetic microparticles, allowing stringent washes. The presented sensor showed a similar limit of detection when the assays were conducted in samples containing total miRNA extracted from human serum, demonstrating its suitability for detecting small specific oligonucleotide sequences under real-like conditions. The strategy of combining UCNPs, magnetic microparticles, and photoligation reaction provides new insight into low-cost, rapid, and ultra-sensitive detection of oligonucleotide sequences.
Received 6 October 2020, Accepted 21 February 2021, Available online 11 March 2021.