CRISPR/Cas12a-Derived electrochemical aptasensor for ultrasensitive detection of COVID-19 nucleocapsid protein

Electrochemical Sensor for the Detection and Accurate Early Diagnosis of Ovarian Cancer

Ovarian cancer (OC) has the highest mortality rate among malignant tumors, primarily because it is difficult to diagnose early. Exosomes, a type of extracellular vesicle rich in parental information, have garnered significant attention in the field of cancer diagnosis and treatment. They play an important regulatory role in the occurrence, development, and metastasis of OC. Consequently, exosomes have emerged as noninvasive biomarkers for early cancer detection. Therefore, identifying cancer-derived exosomes may offer a novel biomarker for the early detection of OC. In this study, we developed a metal-organic frameworks assembled "double hook"-type aptamer electrochemical sensor, which enables accurate early diagnosis of OC. Under optimal experimental conditions, electrochemical impedance spectroscopy technology demonstrated a good linear relationship within the concentration range of 31-3.1 × 106 particles per microliter, with a detection limit as low as 12 particles per microliter. The universal exosome detection platform is constructed, and this platform can not only differentiate between high-grade serous ovarian cancer (HGSOC) patients and healthy individuals but also distinguish between HGSOC patients and nonhigh-grade serous OC (non-HGSOC). Consequently, it provides a novel strategy for the early diagnosis of OC and holds great significance in clinical differential diagnosis.

A universal electrochemical biosensor based on CRISPR/Cas12a and a DNA tetrahedron for ultrasensitive nucleic acid detection

Herein, a universal nucleic acid analysis platform was constructed for sensitive and accurate detection of miRNA-155 and ctDNA using isothermal amplification-assisted CRISPR/Cas12a and a tetrahedral DNA nanostructure (TDN) supported sensing interface. Under the optimal experimental conditions, the prepared sensor achieved specific detection of miRNA-155 and ctDNA at as low as aM levels in 2.6 h. Furthermore, the platform was also successfully applied to human serum sample recovery experiments and cancer cell lysates, demonstrating outstanding reliability and accuracy. We firmly believe that this work provides a universal, sensitive, and practical tool for early clinical diagnosis.

Aptamer-based assembly systems for SARS-CoV-2 detection and therapeutics

Nucleic acid aptamers are oligonucleotide chains with molecular recognition properties. Compared with antibodies, aptamers show advantages given that they are readily produced via chemical synthesis and elicit minimal immunogenicity in biomedicine applications. Notably, aptamer-encoded nucleic acid assemblies further improve the binding affinity of aptamers with the targets due to their multivalent synergistic interactions. Specially, aptamers can be engineered with special topological arrangements in nucleic acid assemblies, which demonstrate spatial and valence matching towards antigens on viruses, thus showing potential in the detection and therapeutic applications of viruses. This review presents the recent progress on the aptamers explored for SARS-CoV-2 detection and infection treatment, wherein applications of aptamer-based assembly systems are introduced in detail. Screening methods and chemical modification strategies for aptamers are comprehensively summarized, and the types of aptamers employed against different target domains of SARS-CoV-2 are illustrated. The evolution of aptamer-based assembly systems for the detection and neutralization of SARS-CoV-2, as well as the construction principle and characteristics of aptamer-based DNA assemblies are demonstrated. The typically representative works are presented to demonstrate how to assemble aptamers rationally and elaborately for specific applications in SARS-CoV-2 diagnosis and neutralization. Finally, we provide deep insights into the current challenges and future perspectives towards aptamer-based nucleic acid assemblies for virus detection and neutralization in nanomedicine.

Improving synthesis and binding affinities of nucleic acid aptamers and their therapeutics and diagnostic applications

Nucleic acid aptamers have captivated the attention of analytical and medicinal scientists globally due to their several advantages as recognition molecules over conventional antibodies because of their small size, simple and inexpensive synthesis, broad target range, and high stability in varied environmental conditions. These recognition molecules can be chemically modified to make them resistant to nuclease action in blood serum, reduce rapid renel clearance, improve the target affinity and selectivity, and make them amenable to chemically conjugate with a support system that facilitates their selective applications. This review focuses on the development of efficient aptamer candidates and their application in clinical diagnosis and therapeutic applications. Significant advances have been made in aptamer-based diagnosis of infectious and non-infectious diseases. Collaterally, the progress made in therapeutic applications of aptamers is encouraging, as evident from their use in diagnosing cancer, neurodegenerative diseases, microbial infection, and in imaging. This review also updates the progress on clinical trials of many aptamer-based products of commercial interests. The key development and critical issues on the subject have been summarized in the concluding remarks.

COVID-19 electrochemical immunosensor with Ag-MOF: Rapid and high-selectivity nasal swab testing for effective detection

Early detection of the coronavirus is acknowledged as a crucial measure to mitigate the spread of the pandemic, facilitating timely isolation of infected individuals, and disrupting the transmission chain. In this study, we leveraged the properties of synthesized Ag-MOF, including high porosity and increased flow intensity. Electrochemical techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to develop an economical and portable sensor with exceptional selectivity for COVID-19 detection. The methodology involves the deposition of Ag-MOF onto the surface of a Glassy Carbon Electrode (GCE), which resulted in a progressive augmentation of electric current. Subsequently, the targeted antibodies were applied, and relevant tests were conducted. The sensor demonstrated the capacity to detect the virus within a linear range of 100 fM to 10 nM, boasting a noteworthy Limit of Detection (LOD) of 60 fM. The entire detection process could be completed in a brief duration of 20 min, exhibiting high levels of accuracy and precision, outperforming comparable techniques in terms of speed and efficacy.

Rapid and Sensitive Detection of Inactivated SARS-CoV-2 Virus via Fiber-Optic and Electrochemical Impedance Spectroscopy Based Aptasensors

The development of rapid detection tools for viruses is vital for the prevention of pandemics and biothreats. Aptamers that target inactivated viruses are attractive for sensors due to their improved biosafety. Here, we evaluated a DNA aptamer (named as 6.9) that specifically binds to the inactivated SARS-CoV-2 virus with a low dissociation constant (KD = 9.6 nM) for the first time. Based on aptamer 6.9, we developed a fiber-optic evanescent wave (FOEW) biosensor. Inactivated SARS-CoV-2 and the Cy5.5-tagged short complementary strand competitively bound with the aptamer immobilized on the surface of the sensor. The detection of the inactivated SARS-CoV-2 virus was realized within six minutes with a limit of detection (LOD, S/N = 3) of 740 fg/mL. We also developed an electrochemical impedance aptasensor which exhibited an LOD of 5.1 fg/mL and high specificity. We further demonstrated that the LODs of the FOEW and electrochemical impedance aptasensors were, respectively, more than 1000 and 100,000 times lower than those of commercial colloidal gold test strips. We foresee that the facile aptamer isolation process and sensor design can be easily extended for the detection of other inactivated viruses.

CRISPR-Cas12a-based colorimetric aptasensor for aflatoxin M1 detection based on oxidase-mimicking activity of flower-like MnO2 nanozymes

Given the highly mutagenic and carcinogenic nature of Aflatoxin M1 (AFM1), the quantity assessment of AFM1 residues in milk and dairy products is necessary to maintain consumer health and food safety. Herein, CRISPR-Cas12a-based colorimetric aptasensor was developed using the catalytic activity of flower-like nanozymes of MnO2 and trans-cleavage property of CRISPR-Cas12a system to quantitatively detect AFM1. The basis of the developed colorimetric aptasensor relies on whether or not the CRISPR-Cas12a system is activated, as well as the contrast in oxidase-mimicking capability exhibited by flower-like MnO2 nanozymes when AFM1 is absent or present. When AFM1 is not present in the sample, single-stranded DNA (ssDNA) is degraded by the activated CRISPR-Cas12a, and the solution turns into yellow due to the catalytic activity of the nanozymes. While, in the attendance of AFM1, ssDNA degradation does not occur due to the inactivation of the CRISPR-Cas12a. Therefore, with the adsorption of the ssDNA on the MnO2 nanozymes, their catalytic activity decreases, and the solution color becomes pale yellow due to less oxidation of the chromogenic substrate. In this aptasensor, the relative absorbance changes increased linearly from 6 to 160 ng L-1, and the detection limit was 2.1 ng L-1. The developed aptasensor displays a selective detection performance and a practical application for quantitative analysis of AFM1 in milk samples. The results of the introduced aptasensor open up the way to design other selective and sensitive aptasensors for the detection of other mycotoxins by substitution of the used sequences.

Solid-Phase Extraction and Enhanced Amplification-Free Detection of Pathogens Integrated by Multifunctional CRISPR-Cas12a

Public healthcare demands effective and pragmatic diagnostic tools to address the escalating challenges in infection management in resource-limited areas. Recent advances in clustered regularly interspaced short palindromic repeat (CRISPR)-based biosensing promise the development of next-generation tools for disease diagnostics, including point-of-care (POC) testing for infectious diseases. The currently prevailing strategy of developing CRISPR/Cas-based diagnostics exploits only the target identification and trans-cleavage activity of a CRISPR-Cas12a/Cas13a system to provide diagnostic results, and they need to be combined with an additional preamplification reaction to enhance sensitivity. In contrast to this dual-function strategy, here, we present a new approach that collaboratively integrates the triple functions of CRISPR-Cas12a: target identification, sequence-specific enrichment, and signal generation. With this approach, we develop a nucleic acid assay termed Solid-Phase Extraction and Enhanced Detection Assay integrated by CRISPR-Cas12a (SPEEDi-CRISPR) that negates the need for preamplification but significantly improves the detection of limit (LOD) from the pM to fM level. Specifically, using Cas12a-coated magnetic beads, this assay combines efficient solid-phase extraction and enrichment of DNA targets enabled by the sequence-specific affinity of CRISPR-Cas12a with fluorogenic detection by activated Cas12a on beads. SPEEDi-CRISPR, for the first time, leverages the possibility of employing CRISPR/Cas12a in nucleic acid extraction and integrates the ability of both enrichment and detection of CRISPR/Cas into a single platform. Our proof-of-concept studies revealed that the SPEEDi-CRISPR assay has great specificity to distinguish HPV-18 from HPV-16, and Parvovirus B19, in addition to being able to detect HPV-18 at a concentration as low as 2.3 fM in 100 min and 4.7 fM in 60 min. Furthermore, we proved that this assay can be coupled with two point-of-care testing strategies: the smartphone-based fluorescence detector and the lateral flow assay. Overall, these results suggested that our assay could pave a new way for developing CRISPR diagnostics.

Recent advances in electrochemical aptasensors and genosensors for the detection of pathogens

In recent years, pathogenic microorganisms have caused significant mortality rates and antibiotic resistance and triggered exorbitant healthcare costs. These pathogens often have high transmission rates within human populations. Rapid diagnosis is crucial in controlling and reducing the spread of pathogenic infections. The diagnostic methods currently used against individuals infected with these pathogens include relying on outward symptoms, immunological-based and, some biomolecular ones, which mainly have limitations such as diagnostic errors, time-consuming processes, and high-cost platforms. Electrochemical aptasensors and genosensors have emerged as promising diagnostic tools for rapid, accurate, and cost-effective pathogen detection. These bio-electrochemical platforms have been optimized for diagnostic purposes by incorporating advanced materials (mainly nanomaterials), biomolecular technologies, and innovative designs. This review classifies electrochemical aptasensors and genosensors developed between 2021 and 2023 based on their use of different nanomaterials, such as gold-based, carbon-based, and others that employed other innovative assemblies without the use of nanomaterials. Inspecting the diagnostic features of various sensing platforms against pathogenic analytes can identify research gaps and open new avenues for exploration.

CRISPR/Cas12-based electrochemical biosensors for clinical diagnostic and food monitoring

Each organism has a unique sequence of nitrogenous bases in in the form of DNA or RNA which distinguish them from other organisms. This characteristic makes nucleic acid-based detection extremely selective and compare to other molecular techniques. In recent years, several nucleic acid-based detection technology methods have been developed, one of which is the electrochemical biosensor. Electrochemical biosensors are known to have high sensitivity and accuracy. In addition, the ease of miniaturization of this electrochemical technique has garnered interest from many researchers. On the other hand, the CRISPR/Cas12 method has been widely used in detecting nucleic acids due to its highly selective nature. The CRISPR/Cas12 method is also reported to increase the sensitivity of electrochemical biosensors through the utilization of modified electrodes. The electrodes can be modified according to detection needs so that the biosensor's performance can be improved. This review discusses the application of CRISPR/Cas12-based electrochemical biosensors, as well as various electrode modifications that have been successfully used to improve the performance of these biosensors in the clinical and food monitoring fields.

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.

Ultrasensitive Point-of-Care Detection of Protein Markers Using an Aptamer-CRISPR/Cas12a-Regulated Liquid Crystal Sensor (ALICS)

Despite extensive efforts, point-of-care testing (POCT) of protein markers with high sensitivity and specificity and at a low cost remains challenging. In this work, we developed an aptamer-CRISPR/Cas12a-regulated liquid crystal sensor (ALICS), which achieved ultrasensitive protein detection using a smartphone-coupled portable device. Specifically, a DNA probe that contained an aptamer sequence for the protein target and an activation sequence for the Cas12a-crRNA complex was prefixed on a substrate and was released in the presence of target. The activation sequence of the DNA probe then bound to the Cas12a-crRNA complex to activate the collateral cleavage reaction, producing a bright-to-dark optical change in a DNA-functionalized liquid crystal interface. The optical image was captured by a smartphone for quantification of the target concentration. For the two model proteins, SARS-CoV-2 nucleocapsid protein (N protein) and carcino-embryonic antigen (CEA), ALICS achieved detection limits of 0.4 and 20 pg/mL, respectively, which are higher than the typical sensitivity of the SARS-CoV-2 test and the clinical CEA test. In the clinical sample tests, ALICS also exhibited superior performances compared to those of the commercial ELISA and lateral flow test kits. Overall, ALICS represents an ultrasensitive and cost-effective platform for POCT, showing a great potential for pathogen detection and disease monitoring under resource-limited conditions.

A magnetic control enrichment technique combined with terahertz metamaterial biosensor for detecting SARS-CoV-2 spike protein

The highly contagious SARS-CoV-2 virus, responsible for the COVID-19 pandemic continues to pose significant challenges to public health. Developing new methods for early detection and diagnosis is crucial in combatting the disease, mitigating its impact and be prepared for future challenges in pandemic diseases. In this study, we propose a terahertz (THz) biosensing technology that capitalizes on the properties of THz metamaterial in conjunction with magnetic nanoparticles. This approach can accurately identify the SARS-CoV-2 spike protein by pinpointing its location on the THz resonance sources grooved surface. The magnetic nanoparticles are employed to selectively bind with target molecules, and migrate towards the THz metamaterial unit cell when exposed to an applied magnetic field. The presence of target molecules in to the metamaterial variation in the frequency, amplitude, and phase of the resonance response, thus enabling swift, accurate and sensitive detection. To assess the effectiveness of the proposed technique, we have conducted a comparative analysis between real samples on platforms controlled by magnetic manipulation and those without the control. It was confirmed that the proposed THz sensing method demonstrated a linear detection range spanning from 0.005 ng mL-1 to 1000 ng mL-1 with a detection limit of 0.002 ng mL-1. Furthermore, it exhibited a frequency shift of 24 GHz and a stability index of 95%. The THz biosensing technique may pave a new avenue in identifying and preempting the spread of potential pandemic diseases.

Recent advances in aptamer-based platforms for cortisol hormone monitoring

The stressful conditions of today-life make it urgent the timely prevention and treatment of many physiological and psychological disorders related to stress. According to the significant progress made in the near future, rapid, accurate, and on-spot measurement of cortisol hormone as a dominant stress biomarker using miniaturized digital devices is not far from expected. With a special potency in the fields of diagnosis and healthcare monitoring, aptamer-mediated biosensors (aptasensors) are promising for the quantitative monitoring of cortisol levels in the different matrices (sweat, saliva, urine, cerebrospinal fluid, blood serum, etc.). Accordingly, this in-depth study reviews the superior achievements in the aptasensing strategies to detect cortisol hormone with the synergism of diverse two/three dimensional nanostructured materials, enzymatic amplification components, and antibody motifs. The represented discussions offer a universal perspective to achieve lab-on-chip aptasensing arrays as future user-friendly skin-patchable electronic gadgets for on-site and real-time quantification of cortisol levels.

Combining hybrid nanoflowers with hybridization chain reaction for highly sensitive detection of SARS-CoV-2 nucleocapsid protein

BACKGROUND

COVID-19 (coronavirus disease 2019) pandemic has had enormous social and economic impacts so far. The nucleocapsid protein (N protein) is highly conserved and is a key antigenic marker for the diagnosis of early SARS-CoV-2 infection.

RESULTS

In this study, the N protein was first captured by an aptamer (Aptamer 58) coupled to magnetic beads (MBs), which in turn were bound to another DNA sequence containing the aptamer (Aptamer 48-Initiator). After adding 5'-biotinylated hairpin DNA Amplifier 1 and Amplifier 2 with cohesive ends for complementary hybridization, the Initiator in the Aptamer 48-Initiator began to trigger the hybridization chain reaction (HCR), generating multiple biotin-labeled DNA concatamers. When incubated with synthetic streptavidin-invertase-Ca3(PO4)2 hybrid nanoflower (SICa), DNA concatamers could specifically bind to SICa through biotin-streptavidin interaction with high affinity. After adding sucrose, invertase in SICa hydrolyzed sucrose to glucose, whose concentration could be directly read with a portable glucometer, and its concentration was positively correlated with the amount of captured N protein. The method is highly sensitive with a detection limit as low as 1 pg/mL.

SIGNIFICANCE

We believe this study provided a practical solution for the early detection of SARS-CoV-2 infection, and offered a new method for detecting other viruses through different target proteins.

Diverse applications and development of aptamer detection technology

Aptamers have received extensive attention in recent years because of their advantages of high specificity, high sensitivity and low immunogenicity. Aptamers can perform almost all functions of antibodies through the combination of spatial structure and target, which are called "chemical antibodies". At present, aptamers have been widely used in cell imaging, new drug development, disease treatment, microbial detection and other fields. Due to the diversity of modifications, aptamers can be combined with different detection technologies to construct aptasensors. This review focuses on the diversity of aptamers in the field of detection and the development of aptamer-based detection technology and proposes new challenges for aptamers in this field.

Recent Advances in DNA Nanotechnology-Enabled Biosensors for Virus Detection

Virus-related infectious diseases are serious threats to humans, which makes virus detection of great importance. Traditional virus-detection methods usually suffer from low sensitivity and specificity, are time-consuming, have a high cost, etc. Recently, DNA biosensors based on DNA nanotechnology have shown great potential in virus detection. DNA nanotechnology, specifically DNA tiles and DNA aptamers, has achieved atomic precision in nanostructure construction. Exploiting the programmable nature of DNA nanostructures, researchers have developed DNA nanobiosensors that outperform traditional virus-detection methods. This paper reviews the history of DNA tiles and DNA aptamers, and it briefly describes the Baltimore classification of virology. Moreover, the advance of virus detection by using DNA nanobiosensors is discussed in detail and compared with traditional virus-detection methods. Finally, challenges faced by DNA nanobiosensors in virus detection are summarized, and a perspective on the future development of DNA nanobiosensors in virus detection is also provided.

Utility of CRISPR/Cas mediated electrochemical biosensors

Electrochemical biosensors represent a class of sensors that employ biological materials as sensitive elements, electrodes as conversion elements, and potential or current as detection signals. The integration of CRISPR/Cas systems into electrochemical biosensors holds immense potential, offering enhanced versatility, heightened sensitivity and specificity, reduced recovery time, and the ability to capture and identify analytes at low concentrations. In this review, we provided a succinct summary of the fundamental principles underlying electrochemical biosensors and CRISPR/Cas systems, and new progress of electrochemical biosensors based on CRISPR/Cas systems in virus, bacteria, and cancer detections. Besides, we discussed its pros and cons, present gaps, potential problem-solvers, and future prospects. To sum up, CRISPR/Cas mediated electrochemical biosensors will surely benefit us a lot in the detection of cells and microorganisms, and of course in other promising fields.

Harnessing aptamers against COVID-19: a therapeutic strategy

The novel coronavirus crisis caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) was a global pandemic. Although various therapeutic approaches were developed over the past 2 years, novel strategies with more efficient applicability are required to target new variants. Aptamers are single-stranded (ss)RNA or DNA oligonucleotides capable of folding into unique 3D structures with robust binding affinity to a wide variety of targets following structural recognition. Aptamer-based theranostics have proven excellent capability for diagnosing and treating various viral infections. Herein, we review the current status and future perspective of the potential of aptamers as COVID-19 therapies.

Customization of aptamer to develop CRISPR/Cas12a-derived ultrasensitive biosensor

The CRISPR/Cas systems have provided wide biosensing applications. Particularly, the aptamer-involved CRISPR/Cas sensor system powerfully expanded to non-nucleic-acid targets. However, tailoring the sequence of the aptamer to explore the relationship between affinity and the activation of CRISPR/Cas12a trans-cleavage activity has not been reported yet. Herein, we developed a series of new aptamers toward the spike protein 1(S1) of SARS-CoV-2. Surface plasmon resonance measurements showed that the affinity of these aptamers to S1 was at the nM level. Subsequently, a "SET" effect (Sequence Essential Trans-cleavage activity) is discovered for the activation of CRISPR/Cas12a trans-cleavage activity. That is, an aptamer, as the activator, sequence needs to be tailored to activate CRISPR/Cas12a efficiently. A balance should be reached between affinity and activation ability. On the one hand, high affinity ensures target recognition performance, and on the other hand, activation can achieve adequate amplification and output of recognition signals. The optimized sequence (with 27 nucleotides, for short 27-nt) not only recognizes the target with a high affinity and specificity but also can trigger the CRISPR/Cas12a trans-cleavage activity efficiently, showing an excellent detection performance in electrochemical biosensors. The detection limit for SARS-CoV-2 S1 can be low at 1.5 pg mL^-1. The new CRISPR/Cas12a-derived aptasensor also displays a remarkable ability to detect Beta, Delta, and Omicron variants but is selective toward other kinds of proteins. Above all, it is robust for point-of-care testing (POCT) in complex biological fluids, such as saliva, urine, and serum, and provides a universal and scalable detecting platform. Our results provide new insights into aptamer development and a different strategy for COVID-19 antigen detection and biosensor development.

Solid-Phase Extraction and Enhanced Amplification-Free Detection of Pathogens Integrated by Dual-Functional CRISPR-Cas12a

Public healthcare demands effective and pragmatic diagnostic tools to address the escalating challenges in infection management in resource-limited areas. Recent advance in CRISPR-based biosensing promises the development of next-generation tools for disease diagnostics, including point-of-care (POC) testing for infectious diseases. Currently prevailing strategy of developing CRISPR assays exploits only the non-specific trans-cleavage function of a CRISPR-Cas12a/Cas13a system for detection and combines it with an additional pre-amplification reaction to enhance the sensitivity. In contrast to this single-function strategy, here we present a new approach that collaboratively integrates the dual functions of CRISPR-Cas12a: sequence-specific binding and trans-cleavage activity. With this approach, we developed a POC nucleic acid assay termed Solid-Phase Extraction and Enhanced Detection assay Integrated by CRISPR-Cas12a (SPEEDi-CRISPR) that negates the need for preamplification but significantly improves the detection of limit (LOD) from the pM to fM level. Specifically, using Cas12a-coated magnetic beads, this assay combines efficient solid-phase extraction and enrichment of DNA targets enabled by the sequence-specific affinity of CRISPR-Cas12a with the fluorogenic detection by the activated Cas12a on beads. Our proof-of-concept study demonstrated that the SPEEDi-CRISPR assay affords an improved detection sensitivity for human papillomavirus (HPV)-18 with a LOD of 2.3 fM and excellent specificity to discriminate HPV-18 from HPV-16, Parvovirus B19, and scramble HPV-18. Furthermore, this robust assay was readily coupled with a portable smartphone-based fluorescence detector and a lateral flow assay for quantitative detection and visualized readout, respectively. Overall, these results should suggest that our dual-function strategy could pave a new way for developing the next-generation CRISPR diagnostics and that the SPEEDi-CRISPR assay provides a potentially useful tool for point-of-care testing.

Aptamers Targeting Membrane Proteins for Sensor and Diagnostic Applications

Many biological processes (physiological or pathological) are relevant to membrane proteins (MPs), which account for almost 30% of the total of human proteins. As such, MPs can serve as predictive molecular biomarkers for disease diagnosis and prognosis. Indeed, cell surface MPs are an important class of attractive targets of the currently prescribed therapeutic drugs and diagnostic molecules used in disease detection. The oligonucleotides known as aptamers can be selected against a particular target with high affinity and selectivity by iterative rounds of in vitro library evolution, known as Systematic Evolution of Ligands by EXponential Enrichment (SELEX). As an alternative to antibodies, aptamers offer unique features like thermal stability, low-cost, reuse, ease of chemical modification, and compatibility with various detection techniques. Particularly, immobilized-aptamer sensing platforms have been under investigation for diagnostics and have demonstrated significant value compared to other analytical techniques. These "aptasensors" can be classified into several types based on their working principle, which are commonly electrochemical, optical, or mass-sensitive. In this review, we review the studies on aptamer-based MP-sensing technologies for diagnostic applications and have included new methodological variations undertaken in recent years.

Aptamers targeting SARS-COV-2: a promising tool to fight against COVID-19

SARS-CoV-2, the causative agent of COVID-19, remains among the main causes of global mortality. Although antigen/antibody-based immunoassays and neutralizing antibodies targeting SARS-CoV-2 have been successfully developed over the past 2 years, they are often inefficient and unreliable for emerging SARS-CoV-2 variants. Novel approaches against SARS-CoV-2 and its variants are therefore urgently needed. Aptamers have been developed for the detection and inhibition of several different viruses such as HIV, influenza viruses, Middle East respiratory syndrome coronavirus (MERS-CoV), and SARS-CoV. Aptamers targeting SARS-CoV-2 represent a promising tool in the fight against COVID-19, which is of paramount importance for the current and any future pandemics. This review presents recent advances and future trends in the development of aptamer-based approaches for SARS-CoV-2 diagnosis and treatment.

Aptamers dimerization inspired biomimetic clamp assay towards impedimetric SARS-CoV-2 antigen detection

Antigen-detecting rapid diagnostic testing (Ag-RDT) has contributed to containing the spread of SARS-CoV-2 variants of concern (VOCs). In this study, we proposed a biomimetic clamp assay for impedimetric SARS-CoV-2 nucleocapsid protein (Np) detection. The DNA biomimetic clamp (DNA-BC) is formed by a pair of Np aptamers connected via a T₂₀ spacer. The 5'- terminal of the DNA-BC is phosphate-modified and then anchored on the surface of the screen-printed gold electrode, which has been pre-coated with Au@UiO-66-NH₂. The integrated DNA-material sensing biochip is fabricated through the strong Zr-O-P bonds to form a clamp-type impedimetric aptasensor. It is demonstrated that the aptasensor could achieve Np detection in one step within 11 min and shows pronounced sensitivity with a detection limit of 0.31 pg mL^-1. Above all, the aptasensor displays great specificity and stability under physiological conditions as well as various water environments. It is a potentially promising strategy to exploit reliable Ag-RDT products to confront the ongoing epidemic.

CRISPR/Cas-based Aptasensor as an Innovative Sensing Approaches for Food Safety Analysis: Recent Progresses and New Horizons

Food safety is one of the greatest public problems occurring around the world. Chemical, physical, and microbiological hazards could lead to food safety problems, which might occur at all stages of the supply chain. To tackle food safety problems and protect consumer health, specific, accurate, and rapid diagnosis techniques meeting various requirements are the imperative measures to ensure food safety. CRISPR-Cas system, a novel emerging technology, is effectively repurposed in (bio)sensing and has shown a tremendous capability to develop on-site and portable diagnostic methods with high specificity and sensitivity. Among numerous existing CRISPR/Cas systems, CRISPR/Cas13a and CRISPR/Cas12a are extensively employed in the design of biosensors, owing to their ability to cleave both non-target and target sequences. However, the specificity limitation in CRISPR/Cas has hindered its progress. Nowadays, nucleic acid aptamers recognized for their specificity and high-affinity characteristics for their analytes are incorporated into CRISPR/Cas systems. With the benefits of reproducibility, high durability, portability, facile operation, and cost-effectiveness, CRISPR/Cas-based aptasensing approaches are an ideal choice for fabricating highly specific point-of-need analytical tools with enhanced response signals. In the current study, we explore some of the most recent progress in the CRISPR/Cas-mediated aptasensors for detecting food risk factors including veterinary drugs, pesticide residues, pathogens, mycotoxins, heavy metals, illegal additives, food additives, and other contaminants. The nanomaterial engineering support with CRISPR/Cas aptasensors is also signified to achieve a hopeful perspective to provide new straightforward test kits toward trace amounts of different contaminants encountered in food samples.

CRISPR/Cas12a-Assisted Chemiluminescence Sensor for Aflatoxin B1 Detection in Cereal Based on Functional Nucleic Acid and In-Pipet Rolling Circle Amplification

Herein, we report a CRISPR/Cas12a-assisted chemiluminescence sensor for aflatoxin B₁ (AFB₁) detection based on functional nucleic-acid-mediated target recognition and in-pipet rolling circle amplification-mediated signal amplification. In this sensor, we performed rolling circle amplification on the inside of the pipet to enrich horseradish peroxidase (pipet-poly-HRP). When AFB₁ is present, it interacts with functional nucleic acids and results in the release of the activator. The activator is designed to activate the CRISPR/Cas12a system, which cleaves the pipet-poly-HRP to liberate HRP. The freed HRP can then be measured by chemiluminescence to quantify AFB₁. This CRISPR/Cas12a-assisted chemiluminescence sensor enables facile, highly sensitive, and specific detection of AFB₁, with a linear range from 50 pg/mL to 100 ng/mL and a detection limit of 5.2 pg/mL. Furthermore, it exhibits satisfactory recovery and has successfully challenged AFB₁ detection in cereal samples. The proposed sensor offers a novel rapid screening approach that holds great promise for food security monitoring.

CRISPR-Cas based molecular diagnostics for foodborne pathogens

Foodborne pathogenic infection has brought multifaceted issues to human life, leading to an urgent demand for advanced detection technologies. CRISPR/Cas-based biosensors have the potential to address various challenges that exist in conventional assays such as insensitivity, long turnaround time and complex pretreatments. In this perspective, we review the relevant strategies of CRISPR/Cas-assisted diagnostics on foodborne pathogens, focusing on biosensing platforms for foodborne pathogens based on fluorescence, colorimetric, (electro)chemiluminescence, electrochemical, and surface-enhanced Raman scattering detection. It summarizes their detection principles by the clarification of foodborne pathogenic bacteria, fungi, and viruses. Finally, we discuss the current challenges or technical barriers of these methods against broad application, and put forward alternative solutions to improve CRISPR/Cas potential for food safety.

Magnetic/fluorescent dual-modal lateral flow immunoassay based on multifunctional nanobeads for rapid and accurate SARS-CoV-2 nucleocapsid protein detection

The SARS-CoV-2 pandemic has posed a huge challenge to rapid and accurate diagnosis of SARS-CoV-2 in the early stage of infection. In this work, we developed a novel magnetic/fluorescent dual-modal lateral flow immunoassay (LFIA) based on multifunctional nanobeads for rapid and accurate determination of SARS-CoV-2 nucleocapsid protein (NP). The multifunctional nanobeads were fabricated by using polyethyleneimine (PEI) as a mediate shell to combine superparamagnetic Fe₃O₄ core with dual quantum dot shells (MagDQD). The core-shell structure of MagDQD label with high loading density of quantum dots (QDs) and superior magnetic content realized LFIA with dual quantitative analysis modal from the assemblies of individual single nanoparticles. The LFIA integrated the advantages of magnetic signal and fluorescent signal, resulting excellent accuracy for quantitative analysis and high elasticity of the overall detection. In addition, magnetic signal and fluorescent signal both had high sensitivity with the limit of detection (LOD) as 0.235 ng mL^-1 and 0.012 ng mL^-1, respectively. The recovery rates of the methods in simulated saliva samples were 91.36%-103.60% (magnetic signal) and 94.39%-104.38% (fluorescent signal). The results indicate the method has a considerable potential to be an effective tool for diagnose SARS-CoV-2 in the early stage of infection.

Target Recognition- and HCR Amplification-Induced In Situ Electrochemical Signal Probe Synthesis Strategy for Trace ctDNA Analysis

An electrochemical-DNA (E-DNA) sensor was constructed by using DNA metallization to produce an electrochemical signal reporter in situ and hybridization chain reaction (HCR) as signal amplification strategy. The cyclic voltammetry (CV) technique was used to characterize the electrochemical solid-state Ag/AgCl process. Moreover, the enzyme cleavage technique was introduced to reduce background signals and further improve recognition accuracy. On the basis of these techniques, the as-prepared E-DNA sensor exhibited superior sensing performance for trace ctDNA analysis with a detection range of 0.5 fM to 10 pM and a detection limit of 7 aM. The proposed E-DNA sensor also displayed excellent selectivity, satisfied repeatability and stability, and had good recovery, all of which supports its potential applications for future clinical sample analysis.

A novel photoelectrochemical immunosensor based on TiO2@Bi2WO6 hollow microspheres and Ag2S for sensitive detection of SARS-COV-2 nucleocapsid protein

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2) is a cluster of β coronaviruses. The 2019 coronavirus disease (COVID-19) caused by SARS-COV-2 is emerging as a global pandemic. Thus, early diagnosis of SARS-COV-2 is essential to prevent severe outbreaks of the disease. In this experiment, a novel label-free photoelectrochemical (PEC) immunosensor was obtained based on silver sulfide (Ag₂S) sensitized titanium dioxide@bismuth tungstate (TiO₂@Bi₂WO₆) nanocomposite for quantitative detection of SARS-COV-2 nucleocapsid protein. The constructed TiO₂@Bi₂WO₆ hollow microspheres had large specific surface area and could produce high photocurrent intensity under visible light illumination. Ag₂S was in-situ grown on the surface of thioglycolic acid (TGA) modified TiO₂@Bi₂WO₆. In particular, TiO₂@Bi₂WO₆ and Ag₂S formed a good energy level match, which could effectively enhance the photocurrent conversion efficiency and strength the photocurrent response. Ascorbic acid (AA) acted as an effective electron donor to effectively eliminate photogenerated holes. Under optimal experimental conditions, the constructed immunosensor presented a supersensitive response to SARS-COV-2 nucleocapsid protein, with a desirable linear relationship ranged from 0.001 to 50 ng/mL for nucleocapsid protein and a lower detection limit of 0.38 pg/mL. The fabricated sensor exhibited a wide linear range, excellent selectivity, specificity and stability, which provided a valuable referential idea for the detection of SARS-COV-2.

Point-of-care CRISPR/Cas biosensing technology: A promising tool for preventing the possible COVID-19 resurgence caused by contaminated cold-chain food and packaging

The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused great public health concern and has been a global threat due to its high transmissibility and morbidity. Although the SARS-CoV-2 transmission mainly relies on the person-to-person route through the respiratory droplets, the possible transmission through the contaminated cold-chain food and packaging to humans has raised widespread concerns. This review discussed the possibility of SARS-CoV-2 transmission via the contaminated cold-chain food and packaging by tracing the occurrence, the survival of SARS-CoV-2 in the contaminated cold-chain food and packaging, as well as the transmission and outbreaks related to the contaminated cold-chain food and packaging. Rapid, accurate, and reliable diagnostics of SARS-CoV-2 is of great importance for preventing and controlling the COVID-19 resurgence. Therefore, we summarized the recent advances on the emerging clustered regularly interspaced short palindromic repeats (CRISPR)/Cas system-based biosensing technology that is promising and powerful for preventing the possible COVID-19 resurgence caused by the contaminated cold-chain food and packaging during the COVID-19 pandemic, including CRISPR/Cas system-based biosensors and their integration with portable devices (e.g., smartphone, lateral flow assays, microfluidic chips, and nanopores). Impressively, this review not only provided an insight on the possibility of SARS-CoV-2 transmission through the food supply chain, but also proposed the future opportunities and challenges on the development of CRISPR/Cas system-based detection methods for the diagnosis of SARS-CoV-2.

CRISPR/Cas Systems-Inspired Nano/Biosensors for Detecting Infectious Viruses and Pathogenic Bacteria

Infectious pathogens cause severe human illnesses and great deaths per year worldwide. Rapid, sensitive, and accurate detection of pathogens is of great importance for preventing infectious diseases caused by pathogens and optimizing medical healthcare systems. Inspired by a microbial defense system (i.e., CRISPR/ CRISPR-associated proteins (Cas) system, an adaptive immune system for protecting microorganisms from being attacked by invading species), a great many new biosensors have been successfully developed and widely applied in the detection of infectious viruses and pathogenic bacteria. Moreover, advanced nanotechnologies have also been integrated into these biosensors to improve their detection stability, sensitivity, and accuracy. In this review, the recent advance in CRISPR/Cas systems-based nano/biosensors and their applications in the detection of infectious viruses and pathogenic bacteria are comprehensively reviewed. First of all, the categories and working principles of CRISPR/Cas systems for establishing the nano/biosensors are simply introduced. Then, the design and construction of CRISPR/Cas systems-based nano/biosensors are comprehensively discussed. In the end, attentions are focused on the applications of CRISPR/Cas systems-based nano/biosensors in the detection of infectious viruses and pathogenic bacteria. Impressively, the remaining opportunities and challenges for the further design and development of CRISPR/Cas system-based nano/biosensors and their promising applications are proposed.

Research progress of CRISPR-based biosensors and bioassays for molecular diagnosis

CRISPR/Cas technology originated from the immune mechanism of archaea and bacteria and was awarded the Nobel Prize in Chemistry in 2020 for its success in gene editing. Molecular diagnostics is highly valued globally for its development as a new generation of diagnostic technology. An increasing number of studies have shown that CRISPR/Cas technology can be integrated with biosensors and bioassays for molecular diagnostics. CRISPR-based detection has attracted much attention as highly specific and sensitive sensors with easily programmable and device-independent capabilities. The nucleic acid-based detection approach is one of the most sensitive and specific diagnostic methods. With further research, it holds promise for detecting other biomarkers such as small molecules and proteins. Therefore, it is worthwhile to explore the prospects of CRISPR technology in biosensing and summarize its application strategies in molecular diagnostics. This review provides a synopsis of CRISPR biosensing strategies and recent advances from nucleic acids to other non-nucleic small molecules or analytes such as proteins and presents the challenges and perspectives of CRISPR biosensors and bioassays.

CRISPR-Cas12a-Empowered Electrochemical Biosensor for Rapid and Ultrasensitive Detection of SARS-CoV-2 Delta Variant

Coronavirus disease 2019 (COVID-19) is a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The gold standard method for the diagnosis of SARS-CoV-2 depends on quantitative reverse transcription-polymerase chain reaction till now, which is time-consuming and requires expensive instrumentation, and the confirmation of variants relies on further sequencing techniques. Herein, we first proposed a robust technique-methodology of electrochemical CRISPR sensing with the advantages of rapid, highly sensitivity and specificity for the detection of SARS-CoV-2 variant. To enhance the sensing capability, gold electrodes are uniformly decorated with electro-deposited gold nanoparticles. Using DNA template identical to SARS-CoV-2 Delta spike gene sequence as model, our biosensor exhibits excellent analytical detection limit (50 fM) and high linearity (R² = 0.987) over six orders of magnitude dynamic range from 100 fM to 10 nM without any nucleic-acid-amplification assays. The detection can be completed within 1 h with high stability and specificity which benefits from the CRISPR-Cas system. Furthermore, based on the wireless micro-electrochemical platform, the proposed biosensor reveals promising application ability in point-of-care testing.

Progress in Electrochemical Biosensing of SARS-CoV-2 Virus for COVID-19 Management

Rapid and early diagnosis of lethal coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important issue considering global human health, economy, education, and other activities. The advancement of understanding of the chemistry/biochemistry and the structure of the SARS-CoV-2 virus has led to the development of low-cost, efficient, and reliable methods for COVID-19 diagnosis over “gold standard” real-time reverse transcription-polymerase chain reaction (RT-PCR) due to its several limitations. This led to the development of electrochemical sensors/biosensors for rapid, fast, and low-cost detection of the SARS-CoV-2 virus from the patient’s biological fluids by detecting the components of the virus, including structural proteins (antigens), nucleic acid, and antibodies created after COVID-19 infection. This review comprehensively summarizes the state-of-the-art research progress of electrochemical biosensors for COVID-19 diagnosis. They include the detection of spike protein, nucleocapsid protein, whole virus, nucleic acid, and antibodies. The review also outlines the structure of the SARS-CoV-2 virus, different detection methods, and design strategies of electrochemical SARS-CoV-2 biosensors by highlighting the current challenges and future perspectives.

Photoswitchable CRISPR/Cas12a-Amplified and Co3O4@Au Nanoemitter Based Triple-Amplified Diagnostic Electrochemiluminescence Biosensor for Detection of miRNA-141

In this work, a CRISPR/Cas12a initiated switchable ternary electrochemiluminescence (ECL) biosensor combined with a Co3O4@Au nanoemitter is presented for the in vitro monitoring of miRNA-141. Benefiting from the advantages of high-throughput cargo payload capability and superconductivity, three-dimensional reduced graphene oxide (3D-rGO) was designated as an introductory conducting stratum of a paper working electrode (PWE). With the collaborative participation of Co3O4@Au NPs, the transmutation of TPrA in the Ru(bpy)32+/TPrA system can be riotously expedited into exorbitant free radical ions TPrA•, which provoked the exaggeration of the ECL signal. Moreover, the programmable enzyme-free hybrid chain reaction (HCR) amplifier on the PWE surface accurately anchored the assembly of nucleic acid tandem and accomplished the secondary recursion of the signal. Impressively, the multifunctional CRISPR/Cas12a with nonspecific cis/trans-splitting decomposition manipulated the photoswitch of the "on-off" signal state that avoided the false-positive diagnosis. The presented multistrategy cooperative biosensor demonstrated extraordinary sensitivity and specificity, with a low detection limit of 3.3 fM (S/N = 3) in the concentration scope from 10 fM to 100 nM, which fully corresponded to the expectation. Overall, this innovative methodology paved a generous avenue for evaluating multifarious biotransformations and provided a tremendous impetus to the development of real-time diagnosis and clinical detection of other biomarkers.

Recent Progresses in Electrochemical DNA Biosensors for SARS-CoV-2 Detection

Coronavirus disease 19 (COVID-19) is still a major public health concern in many nations today. COVID-19 transmission is now controlled mostly through early discovery, isolation, and therapy. Because of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the contributing factor to COVID-19, establishing timely, sensitive, accurate, simple, and budget detection technologies for the SARS-CoV-2 is urgent for epidemic prevention. Recently, several electrochemical DNA biosensors have been developed for the rapid monitoring and detection of SARS-CoV-2. This mini-review examines the latest improvements in the detection of SARS-COV-2 utilizing electrochemical DNA biosensors. Meanwhile, this mini-review summarizes the problems faced by the existing assays and puts an outlook on future trends in the development of new assays for SARS-CoV-2, to provide researchers with a borrowing role in the generation of different assays.

Aptamers as Recognition Elements for Electrochemical Detection of Exosomes

Exosome analysis is emerging as an attractive noninvasive approach for disease diagnosis and treatment monitoring in the field of liquid biopsy. Aptamer is considered as a promising molecular probe for exosomes detection because of the high binding affinity, remarkable specificity, and low cost. Recently, many approaches have been developed to further improve the performance of electrochemical aptamer based(E-AB) sensors with a lower limit of detection. In this review, we focus on the development of using aptamer as a specific recognition element for exosomes detection in electrochemical sensors. We first introduce recent advances in evolving aptamers against exosomes. Then, we review methods of immobilization aptamers on electrode surfaces, followed by a summary of the main strategies of signal amplification. Finally, we present the insights of the challenges and future directions of E-AB sensors for exosomes analysis.

Hydrophobic Wafer-Scale High-Reproducibility SERS Sensor Based on Silicon Nanorods Arrays Decorated with Au Nanoparticles for Pesticide Residue Detection

High sensitivity and reproducibility are highly desirable to a SERS sensor in diverse detection applications. Moreover, it is a great challenge to determine how to promote the target molecules to be more concentrated on the hotspots of the SERS substrate by engineering a surface with switching interfacial wettability. Along these lines, wafer-scale uniformly hydrophobic silicon nanorods arrays (SiNRs) decorated with Au nanoparticles were designed as the SERS substrate. Typically, the SERS substrate was fabricated by enforcing the polystyrene (PS) sphere self-assembly, as well as the plasma etching and the magnetron sputtering techniques. Consequently, the SERS substrate was treated by soaking within a n-dodecyl mercaptan (NDM) solution at different times in order to obtain adjustable wettabilities. By leveraging the electromagnetic enhancement resulted from the Au nanostructures and enrichment effect induced by the hydrophobicity, the SERS substrate is endowed with efficient SERS capabilities. During the detection of malachite green (MG), an ultralow relative standard deviation (RSD) 4.04-6.14% is achieved and the characteristic signal of 1172 cm^-1 can be detected as low as 1 ng/mL. The proposed SiNRs' structure presents outstanding SERS activity with sensitivity and reproducibility rendering thus an ideal candidate for potential application in analytical detection fields.

CRISPR-Cas12a-mediated label-free electrochemical aptamer-based sensor for SARS-CoV-2 antigen detection

Serological antigen testing has emerged as an important diagnostic paradigm in COVID-19, but often suffers from potential cross-reactivity. To address this limitation, we herein report a label-free electrochemical aptamer-based sensor for the detection of SARS-CoV-2 antigen by integrating aptamer-based specific recognition with CRISPR-Cas12a-mediated signal amplification. The sensing principle is based on the competitive binding of antigen and the preassembled Cas12a-crRNA complex to the antigen-specific aptamer, resulting in a change in the collateral cleavage activity of Cas12a. To further generate an electrochemical signal, a DNA architecture was fabricated by in situ rolling circle amplification on a gold electrode, which serves as a novel substrate for Cas12a. Upon Cas12a-based collateral DNA cleavage, the DNA architecture was degraded, leading to a significant decrease in impedance that can be measured spectroscopically. Using SARS-CoV-2 nucleocapsid antigen as the model, the proposed CRISPR-Cas12a-based electrochemical sensor (CRISPR-E) showed excellent analytical performance for the quantitative detection of nucleocapsid antigen. Since in vitro selection can obtain aptamers selective for many SARS-CoV-2 antigens, the proposed strategy can expand this powerful CRISPR-E system significantly for quantitative monitoring of a wide range of COVID-19 biomarkers.

An Update of Nucleic Acids Aptamers Theranostic Integration with CRISPR/Cas Technology

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas system is best known for its role in genomic editing. It has also demonstrated great potential in nucleic acid biosensing. However, the specificity limitation in CRISPR/Cas has created a hurdle for its advancement. More recently, nucleic acid aptamers known for their high affinity and specificity properties for their targets have been integrated into CRISPR/Cas systems. This review article gives a brief overview of the aptamer and CRISPR/Cas technology and provides an updated summary and discussion on how the two distinctive nucleic acid technologies are being integrated into modern diagnostic and therapeutic applications

The role of electrochemical biosensors in SARS-CoV-2 detection: a bibliometrics-based analysis and review

The global pandemic of COVID-19, which began in late 2019, has resulted in extremely high morbidity and severe mortality worldwide, with important implications for human health, international trade, and national politics. Severe acute respiratory syndrome coronavirus (SARS-CoV-2) is the primary pathogen causing COVID-19. Analytical chemistry played an important role in this global epidemic event, and detection of SARS-CoV-2 even became a part of daily life. Analytical chemists have devoted much effort and enthusiasm to this event, and different analytical techniques have shown very rapid development. Electrochemical biosensors are highly efficient, sensitive, and cost-effective and have been used to detect many highly pathogenic viruses long before this event. However, another fact is that electrochemical biosensors are not the technology of choice for most detection applications. This review describes for the first time the role played by electrochemical biosensors in SARS-CoV-2 detection from a bibliometric perspective. This paper analyzed 254 relevant research papers up to June 2022. The contributions of different countries and institutions to this topic were analyzed. Keyword analysis was used to explore different methodological attempts of electrochemical detection techniques. More importantly, we are trying to find an answer to the question: do electrochemical biosensors have the potential to become a genuinely employable detection technology in an outbreak of infectious disease?

This review describes for the first time the role played by electrochemical biosensors in SARS-CoV-2 detection from a bibliometric perspective.