MicroRNAs (miRNAs) hold potential as biomarkers for numerous cancer types, including myelodysplastic neoplasms (MDS). Here, we present a highly sensitive assay based on the oligonucleotide-triggered release of gold nanoparticles (AuNPs) for the detection of hsa-miR-451a with a surface plasmon resonance biosensor. The performance of the assay is in large part determined by the size and functional coating of AuNPs. Therefore, we investigate AuNPs in a size range from 43 to 170 nm, functionalized with thiol- or biotin-terminated oligonucleotides (AuNPsSdT or AuNPsBdT). Our study reveals that 103 nm AuNPsSdT are the best option to improve the assay performance due to their high colloidal stability, a release efficiency exceeding 90%, and a sensor response enhancement factor exceeding 105. We demonstrate that in conjunction with 103 nm AuNPsSdT, the AuNP release assay can detect hsa-miR-451a at levels down to 40 aM and quantify hsa-miR-451a physiological levels in human blood plasma. Moreover, we use the assay to demonstrate a significant down-regulation of hsa-miR-451a in blood plasma of MDS patients compared to healthy individuals, suggesting the potential relevance of hsa-miR-451a as a prospective MDS biomarker.

Institute of Hematology and Blood Transfusion U Nemocnice 2094 1 128 20 Prague Czech Republic

Institute of Photonics and Electronics of the Czech Academy of Sciences Chaberská 1014 57 182 00 Prague Czech Republic

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