Single-excited double-emission CdTe@CdS quantum dots for use in a fluorometric hybridization assay for multiple tumor-related microRNAs

Signal differentiation models for multiple microRNA detection: a critical review

MicroRNAs (miRNAs) are a class of small, single-stranded non-coding RNAs which have critical functions in various biological processes. Increasing evidence suggested that abnormal miRNA expression was closely related to many human diseases, and they are projected to be very promising biomarkers for non-invasive diagnosis. Multiplex detection of aberrant miRNAs has great advantages including improved detection efficiency and enhanced diagnostic precision. Traditional miRNA detection methods do not meet the requirements of high sensitivity or multiplexing. Some new techniques have opened novel paths to solve analytical challenges of multiple miRNA detection. Herein, we give a critical overview of the current multiplex strategies for the simultaneous detection of miRNAs from the perspective of two different signal differentiation models, including label differentiation and space differentiation. Meanwhile, recent advances of signal amplification strategies integrated into multiplex miRNA methods are also discussed. We hope this review provides the reader with future perspectives on multiplex miRNA strategies in biochemical research and clinical diagnostics.

DNA functionalized double quantum dots-based fluorescence biosensor for one-step simultaneous detection of multiple microRNAs

The disease diagnosis by detecting single microRNAs (miRNAs) can produce high false positive rate. Herein, a novel fluorescence biosensor method for one-step simultaneous detection of multiple miRNAs was proposed by using single-stranded DNA (ssDNA) functionalized double quantum dots (QDs) and black hole quencher (BHQ)-decorated magnetic nanobeads (MNs). MNs were linked with two black hole quenchers (BHQ1 and BHQ3) via a complementary DNA (cDNA). The ssDNA/cDNA hybridization contributed to the fluorescence quenching of double QDs due to the fluorescence resonance energy transfer (FRET) between double QDs and BHQ. In the presence of target miRNA-33 (miR-33) and miRNA-125b (miR-125b), the ssDNA₁ and ssDNA₂ were respectively hybridized with miR-33 and miR-125b to form more stable duplexes. Thus, the double QDs were released into supernatant after the magnetic separation, leading to the fluorescence signals recovery at 537 nm and 647 nm. A wide linear range (0.5 nM-320 nM for miR-33 and 0.1 nM-250 nM for miR-125b) and low limits of detection (0.09 nM for miR-33 and 0.02 nM for miR-125b) were achieved. Moreover, our approach has been demonstrated to simultaneously detect miR-33 and miR-125b in cell extracts. With advantages of high sensitivity, strong specificity, low background and low cost, the strategies show great potentials for the detection of various targets in bioanalysis and disease diagnosis.