Selection of DNA aptamer and its application as an electrical biosensor for Zika virus detection in human serum

Printed circuit boards: system automation and alternative matrix for biosensing

Circuit integration has revolutionized the diagnostic sector by improving the sensing ability and rapidity of biosensors. Bioelectronics has led to the development of point-of-care (PoC) devices, offering superior performance compared with conventional biosensing systems. These devices have lower production costs, are smaller, and have greater reproducibility, enabling the construction of compact sensing modules. Flexible upgrades to the fabrication pattern of the printed circuit board (PCB) remains the most reliable and consistent means so far, offering portability, wearability, a lower detection limit, and smart output integration to these devices. This review summarizes the advances in PCB technology for biosensing devices for introducing automation and their emerging application as an alternative matrix material for detecting various analytes.

Programmable Aptasensor for Regulating CRISPR/Cas12a Activity

CRISPR-mediated aptasensors have gained prevalence for detecting non-nucleic acid targets. However, there is an urgent need to develop an easily customizable design to improve the signal-to-noise ratio, enhance universality, and expand the detection range. In this article, we report a CRISPR-mediated programmable aptasensor (CPAS) platform. The platform includes single-stranded DNA comprising the aptamer sequence, locker DNA, and a crRNA recognition region, forming a hairpin structure through complementary hybridization. With T4 DNA polymerase, the crRNA recognition region was transformed into a complete double-stranded DNA through stem-loop extension, thereby activating the trans-cleavage activity of Cas 12a and generating fluorescence signals. The specific binding between the target molecule and aptamer disrupted the formation of the hairpin structure, altering the fluorescence signals. Notably, the CPAS platform allows for easy customization by simply changing the aptamer sequence and locker DNA, without entailing adjustments to the crRNA. The optimal number of bases in the locker DNA was determined to be seven nucleotides for the SARS-CoV-2 spike (S) protein and four nucleotides for ATP. The CPAS platform exhibited high sensitivity for S protein and ATP detection. Integration with a lateral flow assay enabled sensitive detection within 1 h, revealing its excellent potential for portable analysis.

A sensitive electrochemical aptasensor for zearalenone detection based on target-triggered branched hybridization chain reaction and exonuclease I-assisted recycling

Traditional methods for detecting antibiotic and mycotoxin residues rely on large-scale instruments, which are expensive and require complex sample pretreatment processes and professional operators. Although aptamer-based electrochemical sensors have the advantages of simplicity, speed, low cost, and high sensitivity, most aptamer-based sensors lack a signal amplification strategy due to their direct use of aptamers as probes, resulting in insufficient sensitivity. To solve the sensitivity problem in the electrochemical detection process, a novel electrochemical sensing strategy was established for ultrasensitive zearalenone (ZEN) detection on the basis of exonuclease I (Exo I) and branched hybridization chain reaction (bHCR) to amplify the signal. The amplification strategy showed excellent analytical performance towards ZEN with a low detection limit at 3.1×10-12 mol/L and a wide linear range from 10-11 to 10-6 mol/L. Importantly, the assay was utilized in the corn powder samples with satisfactory results, holding promising applications in food safety detection and environmental monitoring.

Progress in Nano-Biosensors for Non-Invasive Monitoring of Stem Cell Differentiation

Non-invasive, non-destructive, and label-free sensing techniques are required to monitor real-time stem cell differentiation. However, conventional analysis methods, such as immunocytochemistry, polymerase chain reaction, and Western blot, involve invasive processes and are complicated and time-consuming. Unlike traditional cellular sensing methods, electrochemical and optical sensing techniques allow non-invasive qualitative identification of cellular phenotypes and quantitative analysis of stem cell differentiation. In addition, various nano- and micromaterials with cell-friendly properties can greatly improve the performance of existing sensors. This review focuses on nano- and micromaterials that have been reported to improve sensing capabilities, including sensitivity and selectivity, of biosensors towards target analytes associated with specific stem cell differentiation. The information presented aims to motivate further research into nano-and micromaterials with advantageous properties for developing or improving existing nano-biosensors to achieve the practical evaluation of stem cell differentiation and efficient stem cell-based therapies.

Fabrication of Rapid Electrical Pulse-Based Biosensor Consisting of Truncated DNA Aptamer for Zika Virus Envelope Protein Detection in Clinical Samples

Zika virus (ZV) infection causes fatal hemorrhagic fever. Most patients are unaware of their symptoms; therefore, a rapid diagnostic tool is required to detect ZV infection. To solve this problem, we developed a rapid electrical biosensor composed of a truncated DNA aptamer immobilized on an interdigitated gold micro-gap electrode and alternating current electrothermal flow (ACEF) technique. The truncated ZV aptamer (T-ZV apt) was prepared to reduce the manufacturing cost for biosensor fabrication, and it showed binding affinity similar to that of the original ZV aptamer. This pulse-voltammetry-based biosensor was composed of a T-ZV apt immobilized on an interdigitated micro-gap electrode. Atomic force microscopy was used to confirm the biosensor fabrication. In addition, the optimal biosensor performance conditions were investigated using pulse voltammetry. ACEF promoted aptamer-target binding, and the target virus envelope protein was detected in the diluted serum within 10 min. The biosensor waveform increased linearly as the concentration of the Zika envelope in the serum increased, and the detection limit was 90.1 pM. Our results suggest that the fabricated biosensor is a significant milestone for rapid virus detection.

Recent Developments in DNA-Nanotechnology-Powered Biosensors for Zika/Dengue Virus Molecular Diagnostics

Zika virus (ZIKV) and dengue virus (DENV) are highly contagious and lethal mosquito-borne viruses. Global warming is steadily increasing the probability of ZIKV and DENV infection, and accurate diagnosis is required to control viral infections worldwide. Recently, research on biosensors for the accurate diagnosis of ZIKV and DENV has been actively conducted. Moreover, biosensor research using DNA nanotechnology is also increasing, and has many advantages compared to the existing diagnostic methods, such as polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). As a bioreceptor, DNA can easily introduce a functional group at the 5' or 3' end, and can also be used as a folded structure, such as a DNA aptamer and DNAzyme. Instead of using ZIKV and DENV antibodies, a bioreceptor that specifically binds to viral proteins or nucleic acids has been fabricated and introduced using DNA nanotechnology. Technologies for detecting ZIKV and DENV can be broadly divided into electrochemical, electrical, and optical. In this review, advances in DNA-nanotechnology-based ZIKV and DENV detection biosensors are discussed.

Aptamer-Based Electrochemical Biosensors for the Detection of Salmonella: A Scoping Review

The development of rapid, accurate, and efficient detection methods for Salmonella can significantly control the outbreak of salmonellosis that threatens global public health. Despite the high sensitivity and specificity of the microbiological, nucleic-acid, and immunological-based methods, they are impractical for detecting samples outside of the laboratory due to the requirement for skilled individuals and sophisticated bench-top equipment. Ideally, an electrochemical biosensor could overcome the limitations of these detection methods since it offers simplicity for the detection process, on-site quantitative analysis, rapid detection time, high sensitivity, and portability. The present scoping review aims to assess the current trends in electrochemical aptasensors to detect and quantify Salmonella. This review was conducted according to the latest Preferred Reporting Items for Systematic review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A literature search was performed using aptamer and Salmonella keywords in three databases: PubMed, Scopus, and Springer. Studies on electrochemical aptasensors for detecting Salmonella published between January 2014 and January 2022 were retrieved. Of the 787 studies recorded in the search, 29 studies were screened for eligibility, and 15 studies that met the inclusion criteria were retrieved for this review. Information on the Salmonella serovars, targets, samples, sensor specification, platform technologies for fabrication, electrochemical detection methods, limit of detection (LoD), and detection time was discussed to evaluate the effectiveness and limitations of the developed electrochemical aptasensor platform for the detection of Salmonella. The reported electrochemical aptasensors were mainly developed to detect Salmonella enterica Typhimurium in chicken meat samples. Most of the developed electrochemical aptasensors were fabricated using conventional electrodes (13 studies) rather than screen-printed electrodes (SPEs) (two studies). The developed aptasensors showed LoD ranges from 550 CFU/mL to as low as 1 CFU/mL within 5 min to 240 min of detection time. The promising detection performance of the electrochemical aptasensor highlights its potential as an excellent alternative to the existing detection methods. Nonetheless, more research is required to determine the sensitivity and specificity of the electrochemical sensing platform for Salmonella detection, particularly in human clinical samples, to enable their future use in clinical practice.