A novel entropy-driven dual-output mode integrated with DNAzyme for enhanced microRNA detection.

Accurate microRNA (miRNA) detection is pivotal in the diagnosis and monitoring of cancer. Entropy-driven catalysis (EDC) has attracted widespread attention as an enzyme-free, isothermal technique for miRNA detection owing to its inherent simplicity and reliability. However, conventional EDC is a single-output mode, limiting the efficiency of signal amplification. In this study, a novel EDC dual-output mode was employed in conjunction with DNAzyme, resulting in the development of an EDC dual-end DNAzyme (EDC-DED) approach for highly sensitive miRNA detection. In this system, miRNA-21 initiated the EDC reaction, producing a large amount of catalytically active dual-end Mg2+-dependent DNAzyme. The DNAzyme further cleaved the reporter cyclically, generating a notably amplified fluorescence signal. The proposed method achieved a low detection limit of 2 pM. Compared with the traditional EDC single-end DNAzyme (EDC-SED) strategy, the present method exhibited superior amplification efficiency, enhancing detection sensitivity by approximately 46.5-fold. Furthermore, this platform demonstrated ideal specificity, satisfactory reproducibility and acceptable detection capabilities in clinical serum samples. Therefore, the straightforward and convenient strategy is a potential tool for miRNA analysis, which may provide a new perspective for biological analysis and clinical application.

A review on recent advances in assays for DNMT1: a promising diagnostic biomarker for multiple human cancers.

The abnormal expression of human DNA methyltransferases (DNMTs) is closely related with the occurrence and development of a wide range of human cancers. DNA (cytosine-5)-methyltransferase-1 (DNMT1) is the most abundant human DNA methyltransferase and is mainly responsible for genomic DNA methylation patterns. Abnormal expression of DNMT1 has been found in many kinds of tumors, and DNMT1 has become a valuable target for the diagnosis and drug therapy of diseases. Nowadays, DNMT1 has been found to be involved in multiple cancers such as pancreatic cancer, breast cancer, bladder cancer, lung cancer, gastric cancer and other cancers. In order to achieve early diagnosis and for scientific research, various analytical methods have been developed for qualitative or quantitative detection of low-abundance DNMT1 in biological samples and human tumor cells. Herein, we provide a brief explication of the research progress of DNMT1 involved in various cancer types. In addition, this review focuses on the types, principles, and applications of DNMT1 detection methods, and discusses the challenges and potential future directions of DNMT1 detection.

Fluorimetric monitoring of vancomycin using an allosteric probe-initiated sensing platform.

Vancomycin is the first-line drug for infections of methicillin-resistant Staphylococcus aureus (MRSA) and multi-drug-resistant bacteria. The effective therapeutic concentration range of vancomycin is narrow, so it's essential to implement vancomycin therapeutic drug monitoring. However, conventional detection methods have disadvantages of expensive equipment, complicated operation, or poor reproducibility. Herein, a fluorescent sensing platform initiated by an allosteric probe was constructed for simple and sensitive monitoring of vancomycin at a low cost. The key point of this platform is the well-designed allosteric probe, which comprises an aptamer and a trigger sequence. When vancomycin exists, the combination of vancomycin and the aptamer will lead to a conformational change of the allosteric probe, thus exposing the trigger sequence. The trigger can react with the molecular beacon (MB) to generate fluorescent signals. In addition, the allosteric probe combined with hybridization chain reaction (HCR) was applied to develop an amplified platform, the linear range is from 0.5 µg mL-1 to 50 µg mL-1 with the limit of detection (LOD) of 0.26 µg mL-1. Most importantly, this allosteric probe-initiated sensing platform shows good detection ability in human serum samples, and it also indicates great correlation and accuracy compared with HPLC. The present simple and sensitive allosteric probe-initiated platform has the potential to support the therapeutic drug monitoring of vancomycin, which is of great significance to promote the rational use of antibiotics in clinics.

A novel fluorescence biosensor based on double-stranded DNA branch migration-induced HCR and DNAzyme feedback circuit for sensitive detection of Pseudomonas aeruginosa (clean version).

Pseudomonas aeruginosa (P. aeruginosa) is one of the most common bacteria in nosocomial infection. Here, a novel fluorescence biosensor based on double-stranded DNA branch migration-induced hybridization chain reaction (HCR) and DNAzyme feedback circuit was constructed for sensitive detection of P. aeruginosa. The binding of P. aeruginosa with its aptamer on a DNA three-way junction structure initiated the double-stranded DNA branch migration to form two DNA "Y" junction structures. One DNA "Y" junction structure opened the fluorescence-labelled DNA hairpins and triggered the HCR. The other DNA "Y" junction structure formed a double-stranded DNAzyme and cleaved the specific ribonucleotide site, producing new triggering probes to start the next cycle of the double-stranded DNA branch migration. Ultimately, a large number of DNA "Y" junction structures were produced, which greatly promoted signal amplification. Under optimized conditions, the proposed biosensor detected a wide linearity range of 102-107 CFU mL-1, and the limit of detection was 37 CFU mL-1 (S/N = 3). The recovery test results indicated that the biosensor has promising clinical application potential. Because of the simultaneous initiation of the HCR and the DNAzyme feedback circuit through the double-stranded DNA branch migration, the constructed biosensor provided an ideal platform for pathogenic bacteria detection without protein enzymes and complex signal amplification procedures.

Cooperative strand displacement circuit with dual-toehold and bulge-loop structure for single-nucleotide variations discrimination.

Nucleic acid nanotechnologies based on toehold-mediated strand displacement are ideally suited for single-nucleotide variations (SNVs) detection. But only a limited number of means could be used to construct selective hybridization probes via finely designed toehold and regulation of branching migration. Herein, we present a cooperative hybridization strategy relying on a dual-toehold and bulge-loop (DT&BL) probe, coupled with the strand displacement catalytic (SDC) cycle to identify SNVs. The dual-toehold can simultaneously hybridize the 5' and 3' ends of the target, so that it possessed the mutual correction function for improving the specificity in comparison with the single target-binding domain. Insertion of BLs into the dual-toehold probe allows tuning of Gibbs free energy change (ΔG) and control of the reaction rate during branching migration. Using the SDC cycle, the reactivity and selectivity of the DT&BL probe were increased drastically without elaborate competitive sequences. The feasibilities of this platform were demonstrated by the identification of three cancer-related genes. Moreover, the applicability of this biosensor to detect clinical samples showed satisfactory accuracy and reliability. We envision it would offer a new perspective for the construction of highly specific probes based on dynamic DNA nanotechnology, and serves as a promising tool for clinical diagnostics.