Insights of Life Molecules' Dynamic Distribution in Live Cells via Sequence-Structure Bispecific Fluorescent RNA

Near-infrared light-induced homogeneous photoelectrochemical biosensor based on 3D walking nanomotor-assisted CRISPR/Cas12a for ultrasensitive microRNA-155 detection

The dysregulation of microRNA (miRNA) expression levels is intricately linked to a myriad of human diseases, and the precise and delicate detection thereof holds paramount significance in the realm of clinical diagnosis and therapy. Herein, a near-infrared (NIR) light-mediated homogeneous photoelectrochemical (PEC) biosensor was constructed for miRNA-155 detection based on NaYF4: Yb, Tm@ZnIn2S4 (NYF@ ZIS) coupled with a three-dimensional (3D) walking nanomotor-assisted CRISPR/Cas12a strategy. The upconverted light emitted by the NYF in the visible and UV region upon NIR light excitation could be utilized to excite ZIS to produce a photocurrent response. The presence of target miRNA-155 initiated an amplification reaction within the 3D walking nanomotor, resulting in the production of multiple nucleic acid fragments. These fragments could activate the collateral cleavage capability of CRISPR/Cas12a, leading to the indiscriminate cleavage of single-stranded DNA (ssDNA) on ALP-ssDNA-modified magnetic beads and the subsequent liberation of alkaline phosphatase (ALP). The released ALP facilitated the catalysis of ascorbic acid 2-phosphate to generate ascorbic acid as the electron donor to capture the photogenerated holes on the NYF@ZIS surface, resulting in a positively correlated alteration in the photocurrent response. Under optimal conditions, the NIR light-initiated homogeneous PEC biosensor had the merits of good linear range (0.1 fM to 100 pM), an acceptable limit of detection (65.77 aM) for miRNA-155 detection. Considering the pronounced sensitivity, light stability, and low photodamage, this strategy presents a promising platform for detecting various other miRNA biomarkers in molecular diagnostic practice.

A universal orthogonal imaging platform for living-cell RNA detection using fluorogenic RNA aptamers

MicroRNAs (miRNAs) are crucial regulators of gene expression at the post-transcriptional level, offering valuable insights into disease mechanisms and prospects for targeted therapeutic interventions. Herein, we present a class of miRNA-induced light-up RNA sensors (miLS) that are founded on the toehold mediated principle and employ the fluorogenic RNA aptamers Pepper and Squash as imaging modules. By incorporating a sensor switch to disrupt the stabilizing stem of these aptamers, our design offers enhanced flexibility and convertibility for different target miRNAs and aptamers. These sensors detect multiple miRNA targets (miR-21 and miR-122) with detection limits of 0.48 and 0.2 nM, respectively, while achieving a robust signal-to-noise ratio of up to 44 times. Capitalizing on the distinct fluorescence imaging channels afforded by Pepper-HBC620 (red) and Squash-DFHBI-1T (green), we establish an orthogonal miRNA activation imaging platform, enabling the simultaneous visualization of different intracellular miRNAs in living cells. Our dual-color orthogonal miLS imaging platform provides a powerful tool for sequence-specific miRNA imaging in different cells, opening up new avenues for studying the intricate functions of RNA in living cells.