A double-tetrahedral DNA framework based electrochemical biosensor for ultrasensitive detection and release of circulating tumor cells

DNA/RNA-based electrochemical nanobiosensors for early detection of cancers

Nucleic acids, like DNA and RNA, serve as versatile recognition elements in electrochemical biosensors, demonstrating notable efficacy in detecting various cancer biomarkers with high sensitivity and selectivity. These biosensors offer advantages such as cost-effectiveness, rapid response, ease of operation, and minimal sample preparation. This review provides a comprehensive overview of recent developments in nucleic acid-based electrochemical biosensors for cancer diagnosis, comparing them with antibody-based counterparts. Specific examples targeting key cancer biomarkers, including prostate-specific antigen, microRNA-21, and carcinoembryonic antigen, are highlighted. The discussion delves into challenges and limitations, encompassing stability, reproducibility, interference, and standardization issues. The review suggests future research directions, exploring new nucleic acid recognition elements, innovative transducer materials and designs, novel signal amplification strategies, and integration with microfluidic devices or portable instruments. Evaluating these biosensors in clinical settings using actual samples from cancer patients or healthy donors is emphasized. These sensors are sensitive and specific at detecting non-communicable and communicable disease biomarkers. DNA and RNA's self-assembly, programmability, catalytic activity, and dynamic behavior enable adaptable sensing platforms. They can increase biosensor biocompatibility, stability, signal transduction, and amplification with nanomaterials. In conclusion, nucleic acids-based electrochemical biosensors hold significant potential to enhance cancer detection and treatment through early and accurate diagnosis.

Utilizing Electrochemical Biosensors as an Innovative Platform for the Rapid and On-Site Detection of Animal Viruses

Animal viruses are a significant threat to animal health and are easily spread across the globe with the rise of globalization. The limitations in diagnosing and treating animal virus infections have made the transmission of diseases and animal deaths unpredictable. Therefore, early diagnosis of animal virus infections is crucial to prevent the spread of diseases and reduce economic losses. To address the need for rapid diagnosis, electrochemical sensors have emerged as promising tools. Electrochemical methods present numerous benefits, including heightened sensitivity and selectivity, affordability, ease of use, portability, and rapid analysis, making them suitable for real-time virus detection. This paper focuses on the construction of electrochemical biosensors, as well as promising biosensor models, and expounds its advantages in virus detection, which is a promising research direction.

Circulating Tumor Cells Adhesion: Application in Biosensors

The early and non-invasive diagnosis of tumor diseases has been widely investigated by the scientific community focusing on the development of sensors/biomarkers that act as a way of recognizing the adhesion of circulating tumor cells (CTCs). As a challenge in this area, strategies for CTCs capture and enrichment currently require improvements in the sensors/biomarker's selectivity. This can be achieved by understanding the biological recognition factors for different cancer cell lines and also by understanding the interaction between surface parameters and the affinity between macromolecules and the cell surface. To overcome some of these concerns, electrochemical sensors have been used as precise, fast-response, and low-cost transduction platforms for application in cytosensors. Additionally, distinct materials, geometries, and technologies have been investigated to improve the sensitivity and specificity properties of the support electrode that will transform biochemical events into electrical signals. This review identifies novel approaches regarding the application of different specific biomarkers (CD44, Integrins, and EpCAm) for capturing CTCs. These biomarkers can be applied in electrochemical biosensors as a cytodetection strategy for diagnosis of cancerous diseases.

Electrochemical Biosensors for Whole Blood Analysis: Recent Progress, Challenges, and Future Perspectives

Whole blood, as one of the most significant biological fluids, provides critical information for health management and disease monitoring. Over the past 10 years, advances in nanotechnology, microfluidics, and biomarker research have spurred the development of powerful miniaturized diagnostic systems for whole blood testing toward the goal of disease monitoring and treatment. Among the techniques employed for whole-blood diagnostics, electrochemical biosensors, as known to be rapid, sensitive, capable of miniaturization, reagentless and washing free, become a class of emerging technology to achieve the target detection specifically and directly in complex media, e.g., whole blood or even in the living body. Here we are aiming to provide a comprehensive review to summarize advances over the past decade in the development of electrochemical sensors for whole blood analysis. Further, we address the remaining challenges and opportunities to integrate electrochemical sensing platforms.

Tetrahedral DNA framework based CRISPR electrochemical biosensor for amplification-free miRNA detection

microRNA (miRNA) is a kind of small non-coding RNA that has been regarded as potential biomarkers for cancers. Sensitive and specific detection of miRNA at low expression levels is highly desirable but remains challenging, especially for amplification-free and portable point of care (POC) diagnostics. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas13a has been recently discovered and used in the field of RNA detection. Nonetheless, most CRISPR/Cas13a-based methods were burdened with expensive equipment, time-consuming procedures, and complicated operations which were not suitable for POC analysis. In this work, we constructed a three-dimensional tetrahedral DNA framework based CRISPR-electrochemical biosensor (CRISPR-E). By combining tetrahedral DNA framework, CRISPR, and electrochemical biosensor, the process of activation, cleavage of Cas13a, and signal readout were all finished on the chip, and a simple, amplification-free and sensitive detection of miRNA-19b was realized. Under the optimal experimental conditions, a linear range from 10 pM to 10⁴ pM with detection limit of 10 pM for miRNA-19b in buffer solution was achieved. Selectivity analysis indicated that our CRISPR-E had good distinguishing ability between miRNA-19b and miRNA-197. The results of miRNA-19b detection in mimic serum samples were consistent with that of the buffer solution. This all-on-chip strategy of our CRISPR-E is very suitable for POC testing.

Dual DNAzyme-catalytic assembly of G-quadruplexes for inducing the aggregation of gold nanoparticles and developing a novel antibiotic assay method

By utilizing a target biorecognition reaction to induce the self-assembly of G-quadruplexes and the aggregation of gold nanoparticles (Au NPs), this work develops a novel colorimetric biosensing method for kanamycin (Kana) antibiotic detection. The compact G-quadruplex structure was assembled from its two half-split sequences which were designed in two hairpin substrates of the Mg²⁺-dependent DNAzyme (MNAzyme). Besides hybridizing with the aptamer strand, the MNAzyme sequence was also split into two half fragments to be designed in the two substrates. Upon the aptamer-recognition reaction toward Kana, the MNAzyme strand could be quantitatively released to cause the exposure of the split G-quadruplex-sequences on two hairpin substrate-modified Au NPs and simultaneous release of two half fragments of the MNAzyme-sequence. Thus, the K⁺-assisted self-folding of G-quadruplexes causes the cross-linking of the two Au NPs to realize the Au NP aggregation-based colorimetric signal output (measured at the largest absorption peak near 520 nm). Meanwhile, the self-assembled formation of the second MNAzyme drastically amplified the signal response. Under the optimal conditions, a wide linear range from 0.1 pg mL^-1 to 10 ng mL^-1 and an ultrahigh sensitivity with the detection limit of 76 fg mL^-1 were obtained. The dose-recovery experiments in real samples showed satisfactory results with recoveries from 98.4 to 105.4% and relative errors compared with the ELISA method less than 4.1%. Due to the high selectivity, excellent repeatability and stability, and simple manipulation, this method indicates a promising potential for practical applications. A novel homogeneous biosensing method was developed for the convenient detection of the kanamycin antibiotic. The target biorecognition-induced and dual DNAzyme-catalytic assembly of G-quadruplexes enabled the amplified aggregation of gold nanoparticles for the simple, cheap, stable, and ultrasensitive colorimetric signal transduction of the method.