Detection of microRNAs by the combination of Exonuclease-III assisted target recycling amplification and repeated-fishing strategy

Modern Methods for Assessment of microRNAs

The review discusses modern methods for the quantitative and semi-quantitative analysis of miRNAs, which are small non-coding RNAs affecting numerous biological processes such as development, differentiation, metabolism, and immune response. miRNAs are considered as promising biomarkers in the diagnosis of various diseases.

Label-free and sensitive microRNA detection method based on the locked nucleic acid assisted fishing amplification strategy

Herein, a label free and sensitive miRNA detection method with enhanced practical applicability was developed based on the locked nucleic acid (LNA) assisted repeated fishing amplification strategy. The working mechanism of the proposed method is as follows: 1) a DNA probe (i.e, L-DNA) with LNA bases is immobilized onto the surface of a gold foil. The L-DNA hybridizes with the 3' terminus of the first strands of complementary deoxyribonucleic acid (cDNA) of the target miRNA in the test samples; 2) The protruding 5' terminus of the cDNA serves as a 'fishhook' to repeatedly fish the products of a hybridization chain reaction (HCR) out from a 'reaction tube'; 3) The HCR products can be unloaded from the gold foil into a 'product tube' through temperature-controlled dehybridization; 4) The concentration of the target miRNA is determined based on the fluorescence intensity generated by the addition of SYBR-Green I (SG) into the 'product tube'. The proposed platform was applied to the detection of miRNA-122 in cell lysate samples and obtained quantitative results with accuracy comparable to the quantitative reverse transcription PCR method (qRT-PCR). It is worth pointing out that the proposed platform achieved a limit of detection value of 2.9 fM for miRNA-122 by a simple but effective LNA-assisted repeated fishing amplification strategy instead of complicated enzyme-based amplification techniques. It is reasonable to expect that the proposed method provides a competitive alternative for designing practically applicable, cost-effective and label-free miRNA detection methods.

Circulating Abnormal Extracellular Vesicles: Their Mechanism for Crossing Blood-Brain Barrier, Effects on Central Nervous System and Detection Methods

Central nervous system (CNS) diseases are difficult to treat and harmful. Many CNS diseases are secondary to peripheral diseases, such as tumor brain metastases (BMS), viral infections and inflammation of the brain, and their pathogenic factors travel through the circulatory system to the brain, eventually leading to lesions. Extracellular vesicles (EVs) play an important role in this process. Recent studies have shown that, extracellular EVs can effectively cross the blood- brain barrier (BBB) through endocytosis and they transmit molecular signals in cell-to-cell communication. Abnormal EVs produced in the lesion portion transport pathogenic factors, including miRNAs, proteins, and virions into the CNS. These pathogenic factors participate in cellular pathways to interfere with homeostasis or are themselves pathogens that directly damage CNS. In addition, different or specific pathological molecules in EVs are potential disease markers. We herein reviewed pathways through which the abnormal EVs cross BBB and adverse effects of abnormal exosomes. We also and summarized their existing detection techniques, so as to provide basis for prevention and early diagnosis of secondary diseases.

Recent Progress in Nanomaterials Modified Electrochemical Biosensors for the Detection of MicroRNA

MicroRNAs (miRNAs) are important non-coding, single-stranded RNAs possessing crucial regulating roles in human body. Therefore, miRNAs have received extensive attention from various disciplines as the aberrant expression of miRNAs are tightly related to different types of diseases. Furthermore, the exceptional stability of miRNAs has presented them as biomarker with high specificity and sensitivity. However, small size, high sequence similarity, low abundance of miRNAs impose difficulty in their detection. Hence, it is of utmost importance to develop accurate and sensitive method for miRNA biosensing. Electrochemical biosensors have been demonstrated as promising solution for miRNA detection as they are highly sensitive, facile, and low-cost with ease of miniaturization. The incorporation of nanomaterials to electrochemical biosensor offers excellent prospects for converting biological recognition events to electronic signal for the development of biosensing platform with desired sensing properties due to their unique properties. This review introduces the signal amplification strategies employed in miRNA electrochemical biosensor and presents the feasibility of different strategies. The recent advances in nanomaterial-based electrochemical biosensor for the detection of miRNA were also discussed and summarized based on different types of miRNAs, opening new approaches in biological analysis and early disease diagnosis. Lastly, the challenges and future prospects are discussed.

Ultra-sensitive MicroRNA-21 detection based on multiple cascaded strand displacement amplification and CRISPR/Cpf1 (MC-SDA/CRISPR/Cpf1)

MicroRNA-21 (miR-21) has been considered as a potential biomarker for cancer diagnosis and prognosis due to its high expression in tumors. Here, an analytical method which integrates the multiple cascaded strand displacement amplification and CRISPR/Cpf1 (MC-SDA/CRISPR/Cpf1) was proposed to ultra-sensitively detect it.