Curvature-Mediated Surface Accessibility Enables Ultrasensitive Electrochemical Human Methyltransferase Analysis

Research progress of human key DNA and RNA methylation-related enzymes assay

Gene methylation-related enzymes (GMREs) are disfunction and aberrantly expressed in a variety of cancers, such as lung, gastric, and pancreatic cancers and have important implications for human health. Therefore，it is critical for early diagnosis and therapy of tumor to develop strategies that allow rapid and sensitive quantitative and qualitative detection of GMREs. With the development of modern analytical techniques and the application of various biosensors, there are numerous methods have been developed for analysis of GMREs. Therefore, this paper provides a systematic review of the strategies for level and activity assay of various GMREs including methyltransferases and demethylase. The detection methods mainly involve immunohistochemistry, colorimetry, fluorescence, chemiluminescence, electrochemistry, etc. Then, this review also addresses the coordinated role of various detection probes, novel nanomaterials, and signal amplification methods. The aim is to highlight potential challenges in the present field, to expand the analytical application of GMREs detection strategies, and to meet the urgent need for future disease diagnosis and intervention.

A label-free fluorescence sensing strategy based on GlaI-assisted EXPAR for rapid and accurate quantification of human methyltranferase activity

DNA methylation plays an important role in epigenetic modification. DNA methyltransferase (DNMT) is essential in the DNA methylation process, and its abnormal expression is closely related to cancer. In this study, we propose a novel biosensor platform (DS-GlaI-EXPAR) that combines hemi-methylated double-stranded DNA (dsDNA) as the substrate for DNMT1 with GlaI-assisted isothermal exponential amplification reaction (EXPAR) for rapid, simple, and sensitive detection of DNMT1 activity. The hemi-methylated dsDNA is fully methylated by DNMT1, and GlaI recognizes and cleaves the fully methylated sequence, generating terminal fragments that trigger EXPAR for efficient signal amplification. Whereas hemi-methylated dsDNA without DNMT1 will keep intact and cannot initiate EXPAR. DNMT1 activity can therefore be sensitively quantified by the real-time fluorescence signal of the DS-GlaI-EXPAR platform. The high-efficiency amplification of EXPAR and the recognition of GlaI enable the platform to overcome the inherent cumbersome and time-consuming shortcomings of traditional methods while meeting specificity and sensitivity. This DS-GlaI-EXPAR platform offers an impressively low limit of detection of 0.86 pg/μL and the entire detection process can be completed in a short time of 2.5 h in a single tube. Furthermore, DNMT1 activity detected by this platform in MCF-7 cells was significantly higher than that of HEK293 cells, and the inhibition of Apt. #9 was verified. This DNMT1 activity detection platform is very convenient and effective for the discovery of inhibitors and early cancer diagnosis.

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.

Silicon microfabrication technologies for biology integrated advance devices and interfaces

Miniaturization is the trend to manufacture ever smaller devices and this process requires knowledge, experience, understanding of materials, manufacturing techniques and scaling laws. The fabrication techniques used in semiconductor industry deliver an exceptionally high yield of devices and provide a well-established platform. Today, these miniaturized devices are manufactured with high reproducibility, design flexibility, scalability and multiplexed features to be used in several applications including micro-, nano-fluidics, implantable chips, diagnostics/biosensors and neural probes. We here provide a review on the microfabricated devices used for biology driven science. We will describe the ubiquity of the use of micro-nanofabrication techniques in biology and biotechnology through the fabrication of high-aspect-ratio devices for cell sensing applications, intracellular devices, probes developed for neuroscience-neurotechnology and biosensing of the certain biomarkers. Recently, the research on micro and nanodevices for biology has been progressing rapidly. While the understanding of the unknown biological fields -such as human brain- has been requiring more research with advanced materials and devices, the development protocols of desired devices has been advancing in parallel, which finally meets with some of the requirements of biological sciences. This is a very exciting field and we aim to highlight the impact of micro-nanotechnologies that can shed light on complex biological questions and needs.

A label-free and ultrasensitive electrochemical biosensor for oral cancer overexpressed 1 gene via exonuclease III-assisted target recycling and dual enzyme-assisted signal amplification strategies

A label-free and ultrasensitive electrochemical biosensor for ORAOV1 gene via exonuclease III-assisted target recycling and dual enzyme-assisted signal amplification strategies. The detection limit of ORAOV1 gene was as low as 0.019 fM.

Dendritic porous silica nanoparticles with high-curvature structures for a dual-mode DNA sensor based on fluorometer and person glucose meter

A dual-mode DNA sensor was constructed to detect nucleic acid sensitively and selectively. Based on dendritic porous silica nanoparticles (DPSNs) and hybridization chain reaction (HCR) amplification strategy, the fabricated DNA sensor showed good sensitivity with low detection limits down to 2.18 pM and 4.02 pM by fluorescence (excited at 488 nm and emitted at 508 nm) and personal glucose meter (PGM) assays, respectively. This dual-mode detection of DNA offered superior reliability and accuracy and could meet the requirements of different testing environments, including laboratory confirmation and portable detection. Moreover, the impact of nanoparticles morphology on detection performance was also discussed. Due to the center-radial pores, DPSNs had high curvature morphology, which improved the coverage capacity, footprint, and deflection angle of probes. This work fabricated a dual-mode DNA sensor and revealed the relationship between morphology and detection performance, which brought new insights in novel biosensor development.

Immunoglobulin G-Based Steric Hindrance Assay for Protein Detection

With the imminent needs of rapid, accurate, simple point-of-care systems for global healthcare industry, electrochemical biosensors have been widely developed owing to their cost-effectiveness and simple instrumentation. However, typical electrochemical biosensors for direct analysis of proteins in the human biological sample still suffer from complex biosensor fabrication, lack of general method, limited sensitivity, and matrix-caused biofouling effect. To resolve these challenges, we developed a general electrochemical sensing strategy based on a designed steric hindrance effect on an antibody surface layer. This strategy utilizes the interaction pattern of protein-G and immunoglobulin G (Fc and Fab regions), providing a steric hindrance effect during the target capturing process. The provided steric hindrance effect minimizes the matrix effect-caused fouling surface and altered the path of electron transfer, delivering a low-fouling and high-sensitivity detection of protein in complex matrices. Also, an enzyme-based horseradish peroxidase/hydroquinone/H₂O₂ transduction system can also be applied to the system, demonstrating the versatility of this sensing strategy for general electrochemical sensing applications. We demonstrated this platform through the detection of Tau protein and programming death ligand 1 with a subpico molar detection limit within 10 min, satisfying the clinical point-of-care requirements for rapid turnaround time and ultrasensitivity.

Electrochemical DNA Biosensing via Electrochemically Controlled Reversible Addition-Fragmentation Chain Transfer Polymerization

Sensitive and selective sensing of biological molecules is fundamental to disease diagnosis and infectious disease surveillance. Herein, an ultrasensitive and highly selective electrochemical DNA biosensor is described by exploiting the electrochemically controlled reversible addition-fragmentation chain-transfer (eRAFT) polymerization as a signal amplification strategy and the peptide nucleic acid (PNA) probes as the recognition elements. Specifically, the PNA probes with a thiol at their 5'-terminals are anchored to a gold electrode surface (via gold-sulfur self-assembly) for sequence-specific recognition of target DNA (tDNA) fragments, of which the phosphate sites serve as the anchorages for the targeted labeling (via the well-established phosphate-Zr⁴⁺-carboxylate chemistry) of the carboxyl-group-containing chain-transfer agents (CTAs) for the succedent eRAFT polymerization, wherein the initiating radicals are generated through electrochemical reduction of aryl diazonium salts under a potentiostatic condition. In the presence of ferrocenylmethyl methacrylate (FcCH═CH₂) as the monomer, the grafting of polymer chains from the CTA-anchored sites as a result of the eRAFT polymerization brings numerous electroactive Fc tags to the electrode surface, outputting a high electrochemical sensing signal even in the presence of trace amounts of tDNA fragments. Under the optimized conditions, the linear range of the described electrochemical DNA biosensor spans from 10 aM to 10 pM ( R² = 0.998), with an attomolar detection limit (4.1 aM) being achieved. Moreover, the described electrochemical DNA biosensor is highly selective and applicable to the sensing of tDNA fragments in complex serum samples. Given its high efficiency, easy operation, and low cost, this biosensor shows great promise in real applications.