Ratiometric electrochemical detection of miRNA based on DNA nanomachines and strand displacement reaction

Ultrasensitive upconverting nanoprobes for in situ imaging of drug-induced liver injury using miR-122 as the biomarker

Drug-induced liver injury (DILI) is a frequent adverse drug reaction. The current clinical diagnostic methods are inadequate for accurate and early detection of DILI due to the lack of effective diagnostic biomarkers. Hepatocyte-specific miR-122 is released from injured hepatocytes promptly and its efflux is significantly correlated with the progression of DILI. Therefore, achieving precise in situ detection of miR-122 with high sensitivity is vital for early visualization of DILI. Herein, a new nanoprobe, consisting of miR-122 aptamer, upconversion nanoparticles (UCNPs) and Prussian blue nanoparticles (PBNPs) was introduced for the early and sensitive detection of DILI in situ. As the nanoprobes reached in the liver, miR-122 aptamer-based entropy-driven strand displacement (ESDR) signal amplification reaction was triggered and luminescence resonance energy transfer (LRET) between UCNPs and PBNPs was responded to achieve the high-fidelity detection of DILI. A negative correlation was observed between the intensity of upconversion luminescence (UCL) and the concentration of miR-122. UCL imaging conducted both in vivo and ex vivo indicated that a reduction in miR-122 concentration led to an increase in UCL intensity, revealing a precise state of DILI. The detection technique demonstrated a positive correlation between signal intensity and severity, offering a more straightforward and intuitive method of visualizing DILI.

Highly sensitive and facile microRNA detection based on target triggered exponential rolling-circle amplification coupling with CRISPR/Cas12a

MicroRNAs (miRNAs) play a crucial role in the regulation of gene expression and have been implicated in many diseases. Herein, we develop a target triggered exponential rolling-circle amplification coupling with CRISPR/Cas12a (T-ERCA/Cas12a) system, which can achieve the ultrasensitive detection with simple operation and no annealing procedure. In this assay, T-ERCA combines the exponential amplification with rolling-circle amplification by introducing a dumb-bell probe with two enzyme recognition sites. miRNA-155 targets are activators that trigger exponential rolling circle amplification to produce large amounts of ssDNA, which is then recognized by CRISPR/Cas12a for further amplification. Compared with single EXPAR or RCA combined with CRISPR/Cas12a, this assay shows higher amplification efficiency. Therefore, benefiting from the excellent amplification effect of T-ERCA and the high recognition specificity of CRISPR/Cas12a, the proposed strategy shows a wide detection range from 1 fM to 5 nM with a LOD (limit of detection) down to 0.31 fM. Moreover, it shows good application ability for assessing miRNA levels in different cells, indicating that the T-ERCA/Cas12a may provide a new guidance for molecular diagnosis and clinical practical application.

A novel ratiometric electrochemical aptasensor for highly sensitive detection of carcinoembryonic antigen

A novel ratiometric electrochemical aptasensor was proposed for carcinoembryonic antigen (CEA) detection based on exonuclease III (Exo III)-assisted recycling and rolling circle amplification (RCA) strategies. A thiolated ferrocene-labeled hairpin probe 2 (Fc-HP2) was fixed on the gold nanoparticles (AuNPs)-modified gold electrode (AuE) surface through Au-S bonds. The presence of CEA led to the release of trigger, which hybridized with the 3'-protruding of hairpin probe 1 (HP1) and triggered the Exo III cleavage reaction, accompanied by the releasing of trigger and generation of new DNA fragment which was used for the successive hybridization with Fc-HP2. After the Exo III cleavage process, the remaining Fc-HP2 fragments hybridized as primers with the RCA template to initiate the RCA process, and long single-stranded polynucleotides were produced for methylene blue (MB) binding. Such changes resulted in the signal of Fc (I_Fc) decreased and that of MB (I_MB) increased, achieving a linear relationship between I_MB/I_Fc and logarithm of CEA concentrations ranging from 1.0 pg mL^-1 to 100.0 ng mL^-1 with a detection limit of 0.59 pg mL^-1. Additionally, the developed aptasensor had been successfully applied to detect CEA in human serum samples. Therefore, the proposed strategy might provide a new platform for clinical detections of CEA.