Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 20 de 382
Filter
1.
Hybrid Advances ; : 100023, 2023.
Article in English | ScienceDirect | ID: covidwho-2210409

ABSTRACT

A sensitive biological system and a detector system with appropriate transducers for obtaining the output signals make up a biosensor. These devices have a wide range of uses, including disease screening, the detection of environmental pollutants, agriculture, and routine medical examinations. The product's selectivity, sensitivity, stability, and lower production costs will all be critical factors in its widespread commercialisation. Recently, scientists have tackled the issue of developing a nano biosensor with a high degree of sensitivity and selectivity for the recognition of biomarkers of immune responses and cancer. The fact that electrochemical nano biosensors may successfully be employed for detecting medications in addition to pathogen biomarkers has significantly altered the covid picture in our favour. During the worldwide epidemic, a number of cutting-edge SARS - CoV-2 biosensors with portable, smartphone-connected instant detection devices were helpful. This article provides a concise summary of the underlying working principle, generations of developments and numerous detection methods employed by electrochemical biosensors.The difficulties, knowledge gaps, and possible solutions in the field of electrochemical biosensors are all discussed in the context of this categorisation.This novel overview also sheds light on the different kinds of electrochemical biosensors and the tasks they perform, as well as recent developments in the "smart biosensor” industry with potential future directions and challenges for this growing subject.

2.
Biosensors and Bioelectronics: X ; : 100307, 2023.
Article in English | ScienceDirect | ID: covidwho-2209882

ABSTRACT

Here we present a sensitive method for the detection and quantification of two (IL -10 and CRP) immuno-responsive biomarkers in various biofluids. The significance of these immune response biomarkers lies in them displaying elevated levels in critically ill COVID -19 patients. The developed electrochemical sensor contains a gold film electrode with ZnO nanoparticles deposited on its surface to increase the surface area of the working electrode while integrating antibody-antigen interactions into the detection system. This multiplex biosensor has a wide linear range from 0.01 μg/mL to 100 μg/mL and 0.1pg/mL to 1000 pg/mL for CRP and IL10, respectively. The cross-reactivity of this multiplex sensor platform was evaluated between these two proteins and was <20%. Recovery studies were performed by spiking known concentrations in serum and urine samples. The recovery was calculated and ranged from 80% to 100%, confirming clinical applicability. This electrochemical sensing platform can aid in the early screening of COVID -19 patients to monitor for the development of more serious and potentially lethal symptoms.

3.
Biosensors and Bioelectronics ; 225:115101, 2023.
Article in English | ScienceDirect | ID: covidwho-2209881

ABSTRACT

The electrochemical biosensor with outstanding sensitivity and low cost is regarded as a viable alternative to current clinical diagnostic techniques for various disease biomarkers. However, their actual analytical use in complex biological samples is severely hampered due to the biofouling, as they are also highly sensitive to nonspecific adsorption on the sensing interfaces. Herein, we have constructed a non-fouling electrochemical biosensor based on antifouling peptides and the electroneutral peptide nucleic acid (PNA), which was used as the recognizing probe for the specific binding of the viral RNA of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Different from the negatively charged DNA probes that will normally weaken the biosensors' antifouling capabilities owing to the charge attraction of positively charged biomolecules, the neutral PNA probe will generate no side-effects on the biosensor. The biosensor demonstrated remarkable sensitivity in detecting SARS-CoV-2 viral RNA, possessing a broad linear range (1.0 fM - 1.0 nM) and a detection limit down to 0.38 fM. Furthermore, the sensing performance of the constructed electrochemical biosensor in human saliva was nearly similar to that in pure buffer, indicating satisfying antifouling capability. The combination of PNA probes with antifouling peptides offered a new strategy for the development of non-fouling sensing systems capable of assaying trace disease biomarkers in complicated biological media.

4.
Bioelectrochemistry ; 151:108375, 2023.
Article in English | ScienceDirect | ID: covidwho-2209868

ABSTRACT

Accurate detection of SARS-CoV-2 spike (SARS-CoV-2-S) protein is of clinical significance for early diagnosis and timely treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein, a surface molecularly imprinted miniature biosensor was fabricated. Au nanoparticles (AuNPs), reduced graphene oxide (rGO), poly(methylene blue)/poly(ionic liquids) and poly(ionic liquids) were successively electrodeposited onto the pinpoint of an acupuncture needle (AN). The molecularly imprinted miniature biosensor was obtained after the template of SARS-CoV-2-S protein was removed, which could be used for sensitive detection of SARS-CoV-2-S protein. The linear range and limit of detection (LOD) were 0.1 ∼ 1000 ng mL−1 and 38 pg mL−1, respectively, which were superior to other molecularly imprinted biosensors previously reported. The developed miniature biosensor also exhibited high specificity and stability. The reliability of the biosensor was evaluated by the detection of SARS-CoV-2-S protein in clinical serum samples.

5.
Chemistryselect ; 8(1), 2023.
Article in English | Web of Science | ID: covidwho-2173451

ABSTRACT

A single-chain variable fragment (scFv) is an antibody fragment composed of VH and VL linked by a hydrophilic linker that can be designed according to the shape of the target molecule and synthesized in prokaryotic or eukaryotic cells via biotechnology engineering. This study developed an electrochemical immunosensor that detects the RBD of SARS-CoV-2 using a screen-printed carbon electrode modified with gold nanoparticles, and scFv as a bioreceptor. Electrochemical impedance spectroscopy was employed to measure specific interactions of antigens with antibodies. The developed immunosensor had a limit of detection and a quantification limit of 4.86 ng mL(-1) and 16.20 ng mL(-1), respectively. The immunosensor was stable at room temperature for up to 30 days' storage. The immunosensor was assessed at biosafety level 3 using 33 nasopharyngeal swab specimens (clinical samples);the pieces of data were compared with quantitative Reverse Transcriptase-PCR. The agreement of the data, the low detection limit achieved, the rapid analysis (30 min), the miniaturization, and the portability of the instrument combined with the easiness to use has the potential to become Point of Care (POC) for diagnosing the COVID-19 disease.

6.
Prakticky Lekar ; 102(4):171-176, 2022.
Article in Czech | Scopus | ID: covidwho-2168132

ABSTRACT

Aim: The review provides basic practical information about the use of biosensors in the rapid diagnosis of viral pathogens. Results: Thanks to evolutionary changes in the genome, viruses jump into the human population, where they cause serious epi-demics. Rapid POCT diagnostic tools based on biosensors will enable their use for clinical diagnosis needs outside of specialized laboratories. The combination of these devices with the techniques of 3D printing, microfluidic systems, nanotechnology and electrochemical detection significantly increases the usability of biosensors. Intensive research is carried out on a wide range of viruses, e.g. HIV, Ebola, influenza, hepatitis viruses. In connection with the global covid-19 pandemic, the development of nanobio-sensors is currently focused primarily on the detection of SARS-CoV-2. Conclusion: Available literature data suggest that fast sensors and biosensors have considerable clinical potential for the use in POCT. © 2022, Czech Medical Association J.E. Purkyne. All rights reserved.

7.
2022 International Conference on Compound Semiconductor Manufacturing Technology, CS MANTECH 2022 ; : 165-168, 2022.
Article in English | Scopus | ID: covidwho-2167790

ABSTRACT

This paper describes the Qorvo Biotechnologies Omnia testing system using bulk acoustic wave (BAW) sensor technology and performance data generated in a study conducted by the National Institutes of Health (NIH) as part of the RADx initiative for SARS-CoV-2 antigen testing. The Qorvo Omnia SARS-CoV-2 Antigen test was granted Emergency Use Authorization (EUA) for the qualitative detection of SARS-CoV-2 nucleocapsid viral antigens from direct anterior nasal swab specimens without transport media from symptomatic individuals who are suspected of COVID-19 by their healthcare provider within the first six days of symptom onset. The study illustrates the ease-of-use of the system and provides specific performance data: Limit of Detection (LoD) determination and a prospective study in two patient cohorts versus two high sensitivity real time polymerase chain reaction (RT-PCR) comparative methods, the Roche cobas® 6800 RT-PCR system (1800 NDU/mL) and the Hologic Panther® RT-PCR system (600 NDU/mL). © 2022 MANTECH 2022. All rights reserved.

8.
Malaysian Journal of Medical Sciences ; 29(6):15-33, 2022.
Article in English | EMBASE | ID: covidwho-2204905

ABSTRACT

Diagnostic testing to identify individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays a key role in selecting appropriate treatments, saving people's lives and preventing the global pandemic of COVID-19. By testing on a massive scale, some countries could successfully contain the disease spread. Since early viral detection may provide the best approach to curb the disease outbreak, the rapid and reliable detection of coronavirus (CoV) is therefore becoming increasingly important. Nucleic acid detection methods, especially real-time reverse transcription polymerase chain reaction (RT-PCR)-based assays are considered the gold standard for COVID-19 diagnostics. Some non-PCR-based molecular methods without thermocycler operation, such as isothermal nucleic acid amplification have been proved promising. Serologic immunoassays are also available. A variety of novel and improved methods based on biosensors, Clustered-Regularly Interspaced Short Palindromic Repeats (CRISPR) technology, lateral flow assay (LFA), microarray, aptamer etc. have also been developed. Several integrated, random-access, point-of-care (POC) molecular devices are rapidly emerging for quick and accurate detection of SARS-CoV-2 that can be used in the local hospitals and clinics. This review intends to summarize the currently available detection approaches of SARS-CoV-2, highlight gaps in existing diagnostic capacity, and propose potential solutions and thus may assist clinicians and researchers develop better technologies for rapid and authentic diagnosis of CoV infection. Copyright © 2022, Penerbit Universiti Sains Malaysia. All rights reserved.

9.
Journal of Prevention of Alzheimer's Disease ; 9(Supplement 1):S158-S159, 2022.
Article in English | EMBASE | ID: covidwho-2203888

ABSTRACT

Background: Chronic neuroinflammation has been implicated in alzheimer's disease (AD) pathology. JAK kinases play a central role in innate immune signaling, often triggering an interferon response. These finding converged with our independent, laboratory study that discovered a strong interferon response in autopsied AD and ALS brains with cytoplasmic TAR DNA-binding protein 43 (TDP-43) inclusions. We found that cytoplasmic inclusions of TDP-43 were associated with cytoplasmic double stranded RNA (cdsRNA), a root cause of interferon signaling and JAK kinase activation. Baricitinib, an FDA approved JAK inhibitor FDA-approved for rheumatoid arthritis, COVID-19, and alopecia, is a top hit in an orthogonal machine learning approach to repurpose drugs in alzheimer's disease. Baricitinib rescued differentiated human neural cell death and neuroinflammation evoked by cdsRNA in a dose dependent manner. In animal models, activation of type I interferon signaling by cdsRNA leads to propagated neurodegeneration within a neural circuit. The interferon response gene, PKR, is a biosensor for dsRNA in neurons. Elevated levels of activated PKR are associated with cognitive decline and progression of disease. Baricitinib lowered PKR levels in human neural cells and baricitinib structural analog lowers levels of PKR in an AD patient. Moreover, we further validated that baricitinib rescues neuroinflammation and neuronal death in a mouse model of cdsRNA-evoked neurodegeneration. We seek to further validate this mechanism of action in patients with AD, mild cognitive decline (MCI), or subjective cognitive decline (SCD) who have elevated markers of interferon signaling in their cerebrospinal fluid (CSF). Objective(s): The primary objectives of the study are: 1. to assess whether an oral dose of baricitinib 2 mg and 4 mg per day achieves measurable levels of baricitinib in the CSF of patients with AD. 2. To determine whether an oral dose of baricitinib 2 mg or 4 mg per day decreases levels of the inflammatory biomarker chemokine ligand 2 (CCL2) in the CSF of patients with AD, MCI, or SCD. The secondary objectives of the study are: 1. to determine whether an oral doses of baricitinib 2 mg and 4 mg per day decrease levels of the inflammatory biomarkers, phospho-protein kinase R (pPKR), PKR, the pPKR / PKR ratio, C-X-C motif chemokine ligand 10 (CXCL10), and Interferon Gamma (IFNG) in the CSF of patients with AD, MCI, or SCD;2. to determine whether the oral doses of baricitinib 2 mg and 4 mg per day decrease levels of neuronal death biomarkers of neurofilament light chain (NfL), tau, and phospho-tau in CSF and TDP-43 levels in the plasma in patients with AD, MCI, or SCD. 3. to determine whether the measured concentration of baricitinib in the CSF or blood (pharmacokinetics) correlates with the changes in CSF biomarkers (pharmacodynamics);4. to demonstrate that baricitinib 2 mg and 4 mg by mouth daily is safe and tolerable in patients with AD, MCI, and SCD. Method(s): This is a leadin, open-label, biomarker-driven trial of baricitinib in patients with AD, MCI, and SCD (NCT05189106). All participants will have a lumbar puncture (LP) at screening, and if their CSF level of CCL2 is >= 250 pg/mL, participants will be enrolled. After 8 weeks, a baseline LP will be performed, and each participant will treated with open-label baricitinib 2 mg by mouth daily for 8 weeks. A third LP will be performed after 8 weeks on the drug. CSF examination will be conducted to measure levels of study drug in the plasma and CSF two to four hours after dosing and levels of CCL2 (MCP1), pPKR, PKR, pPKR/PKR, CXCL10, IFNG, nNfL, Abeta, tau, and phospho-tau as well as exploratory biomarkers. Blood will be collected for safety labs, and to measure levels of TDP-43 and exploratory biomarkers in the plasma. The baricitinib dose will be increased to 4 mg by mouth daily with a fourth LP and CSF examination will be conducted at the Week 16 Visit. Clinical endpoints such as the ADAS-COG, a cognitive battery will be collected at final clinic visit at 24 weeks. Result(s): CCL2 vels are elevated in about 50% of patients diagnosed with AD, MCI, and SCD from the Massachusetts alzheimer's Disease Research Center BioBank, which is consistent with the prevalence of TDP-43 inclusions in AD brains. Conclusion(s): We are conducting a pilot clinical trial to determine whether baricitinib 1. significantly reduces inflammatory and/or neuronal death biomarkers in the CSF, 2. is safe and tolerable in AD, MCI, and SCD patients. Unbiased analysis of proteomics of CSF samples may refine the biomarker profile of patients that responded to baricitinib. Regardless if the clinical trial achieves its endpoints, this biomarker discovery work can be incorporated into future AD clinical trials to offer more precise eligibility criteria and deep phenotyping.

10.
Frontiers in Cellular and Infection Microbiology ; 12, 2022.
Article in English | Web of Science | ID: covidwho-2198724

ABSTRACT

The number of words: 4645, the number of figures: 4, the number of tables: 1The outbreak of COVID-19 in December 2019 caused a global pandemic of acute respiratory disease, and with the increasing virulence of mutant strains and the number of confirmed cases, this has resulted in a tremendous threat to global public health. Therefore, an accurate diagnosis of COVID-19 is urgently needed for rapid control of SARS-CoV-2 transmission. As a new molecular biology technology, loop-mediated isothermal amplification (LAMP) has the advantages of convenient operation, speed, low cost and high sensitivity and specificity. In the past two years, rampant COVID-19 and the continuous variation in the virus strains have demanded higher requirements for the rapid detection of pathogens. Compared with conventional RT-PCR and real-time RT-PCR methods, genotyping RT-LAMP method and LAMP plus peptide nucleic acid (PNA) probe detection methods have been developed to correctly identified SARS-CoV-2 variants, which is also why LAMP technology has attracted much attention. LAMP detection technology combined with lateral flow assay, microfluidic technology and other sensing technologies can effectively enhance signals by nucleic acid amplification and help to give the resulting output in a faster, more convenient and user-friendly way. At present, LAMP plays an important role in the detection of SARS-CoV-2.

11.
Current pharmaceutical biotechnology ; 02, 2023.
Article in English | EMBASE | ID: covidwho-2197790

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), commonly known as COVID-19, created rack and ruin and erupted as a global epidemic. Nearly 482.3 million cases and approximately 6.1 million deaths have been reported. The World Health Organization (WHO) designated it an international medical emergency on January 30, 2020;shortly in March 2020, it was declared a pandemic. To address this situation, governments and scientists around the globe were urged to combat and prevent its spread, mainly when no treatment was available. Presently, quantitative real-time polymerase chain reaction (qRT-PCR) is the most widely utilized technique for diagnosing SARS-CoV-2. But this method is cumbersome, tedious, and might not be quickly accessible in isolated areas with a circumscribed budget. Therefore, there is a quest for novel diagnostic techniques which can diagnose the disease in a lesser time in an economical way. This paper outlines the potential of biosensors in the diagnosis of SARS-CoV-2. This review highlights the current state of presently available detection techniques, expected potential limits, and the benefits of biosensor-implicated tests against SARS-Cov-2 diagnosis. CRISPR-Cas9 implanted paper strip, field-effect transistor (FET) implanted sensor, nucleic-acid centric, aptamers-implanted biosensor, antigen-Au/Ag nanoparticles-based electrochemical biosensor, surface-enhanced Raman scattering (SERS)-based biosensor, Surface Plasmon Resonance, potential electrochemical biosensor, optical biosensor, as well as artificial intelligence (AI) are some of the novel biosensing devices that are being utilized in the prognosis of coronaviruses. Copyright© Bentham Science Publishers;For any queries, please email at epub@benthamscience.net.

12.
New Journal of Chemistry ; 2022.
Article in English | EMBASE | ID: covidwho-2186152

ABSTRACT

The separation of highly pure single-chirality single-walled carbon nanotubes (SWCNTs) is challenging and also in demand due to their intrinsic physical, optical, and electronic properties. The use of single-chirality and their performance characteristics makes them a selective candidate for multifunctional applications and opens a new front in nanotube development. It has previously been reported that SWCNTs can be separated in various ways by employing direct control and post-synthesis approaches. Herein, we review the separation of single-chiralities of SWCNTs on account of simplicity and time/cost effectiveness by using gel chromatography. The most recent progress in the controlled synthesis of SWCNTs is comprehensively reviewed in terms of selective-diameter, single-chirality, and specific geometric shape. The method to achieve the single-chirality of SWCNTs is also highlighted. Besides addressing COVID-19 characteristics, epidemiology, and pathology, we also review the most recent developments in nano-biosensors for the rapid and early detection of COVID-19. Furthermore, the photothermal/bioimaging response of single-chirality is reviewed in order to enhance the cytotoxicity of drugs against cancer cells over simple carbon nanotubes (CNTs). The single-chirality allows for precise imaging (due to efficient absorption and emission) of tumors/blood vessels up to ~10-fold higher by injecting a low dose. We hope this review stimulates further study on single-chirality controlled SWCNTs for practical applications. Copyright © 2023 The Royal Society of Chemistry.

13.
Nanoscale Advances ; 2022.
Article in English | Web of Science | ID: covidwho-2186150

ABSTRACT

The current COVID-19 pandemic, with its numerous variants including Omicron which is 50-70% more transmissible than the previously dominant Delta variant, demands a fast, robust, cheap, and easily deployed identification strategy to reduce the chain of transmission, for which biosensors have been shown as a feasible solution at the laboratory scale. The use of nanomaterials has significantly enhanced the performance of biosensors, and the addition of CNTs has increased detection capabilities to an unrivaled level. Among the various CNT-based detection systems, CNT-based field-effect transistors possess ultra-sensitivity and low-noise detection capacity, allowing for immediate analyte determination even in the presence of limited analyte concentrations, which would be typical of early infection stages. Recently, CNT field-effect transistor-type biosensors have been successfully used in the fast diagnosis of COVID-19, which has increased research and commercial interest in exploiting current developments of CNT field-effect transistors. Recent progress in the design and deployment of CNT-based biosensors for viral monitoring are covered in this paper, as are the remaining obstacles and prospects. This work also highlights the enormous potential for synergistic effects of CNTs used in combination with other nanomaterials for viral detection.

14.
ACS Appl Nano Mater ; 5(12):17503-17507, 2022.
Article in English | Web of Science | ID: covidwho-2185499

ABSTRACT

In this work, we report a 5-min magnetic particle spectroscopy (MPS)-based bioassay strategy. In our approach, surface-functionalized magnetic nanoparticles are incubated with target analytes at 37 degrees C with agitation for 3 min, and the MPS reading is then taken at the fifth minute. We prove the feasibility of 5 min ultrafast detection of SARS-CoV-2 spike protein with a detection limit below 5 nM (0.2 pmol). Our proposed 5-min bioassay strategy may be applied to reduce the assay time for other liquid-phase, volumetric biosensors such as NMR, quantum dots, fluorescent biosensors, etc.

15.
Talanta ; 254:124167, 2023.
Article in English | Scopus | ID: covidwho-2183602

ABSTRACT

Outbreaks of emerging viral respiratory infectious diseases (VRIDs) including coronavirus disease 2019 (COVID-19) seriously endanger people's health. However, the traditional nucleic acid detection required professionals and larger instruments and antigen-antibody detection suffered a long window period of target generation. To facilitate the VRIDs detection in time for common populations, a smartphone-controlled biosensor, which integrated sample preparation (electromembrane extraction), biomarker detection (red-green-blue model) and remote response technology (a built-in APP), was developed in this work. With the intelligent biosensor, VRIDs could be recognized in the early stage by using endogenous hydrogen sulfide as the biomarker. Importantly, it only took 15 min to accomplish the whole process of screening and response to VRIDs. Moreover, the experimental data showed that this smartphone-controlled biosensor was suitable for ordinary residents and could successfully differentiate non-communicable respiratory diseases from VRIDs. To the best of our knowledge, this is the first time that a smartphone-controlled biosensor for screening and response to VRIDs was reported. We believe that the present biosensor will help ordinary residents jointly deal with the challenges brought by COVID-19 or other VRIDs in the future. Copyright © 2022 Elsevier B.V. All rights reserved.

16.
Sensors and Actuators B: Chemical ; : 133387, 2023.
Article in English | ScienceDirect | ID: covidwho-2183394

ABSTRACT

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 11min and shows pronounced sensitivity with a detection limit of 0.31pgmL–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.

17.
Sensing and Bio-Sensing Research ; : 100549, 2023.
Article in English | ScienceDirect | ID: covidwho-2183030

ABSTRACT

Viral outbreaks, which include the ongoing coronavirus disease 2019 (COVID-19) pandemic provoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are a major global crisis that enormously threaten human health and social activities worldwide. Consequently, the rapid and repeated treatment and isolation of these viruses to control their spread are crucial to address the COVID-19 pandemic and future epidemics of novel emerging viruses. The application of cost-efficient, rapid, and easy-to-operate detection devices with miniaturized footprints as a substitute for the conventional optic-based polymerase chain reaction (PCR) and immunoassay tests is critical. In this context, semiconductor-based electrical biosensors are attractive sensing platforms for signal readout. Therefore, this study aimed to examine the electrical sensing of patient-derived SARS-CoV-2 samples by harnessing the activity of DNA aptamers directed against spike proteins on viral surfaces. We obtained rapid and sensitive virus detection beyond the Debye length limitation by exploiting aptamers coupled with alkaline phosphatases, which catalytically generate free hydrogen ions which can readily be measured on pH meters or ion-sensitive field-effect transistors. Furthermore, we demonstrated the detection of the viruses of approximately 100 copies/μL in 10 min, surpassing the capability of typical immunochromatographic assays. Therefore, our newly developed technology has great potential for point-of-care testing not only for SARS-CoV-2, but also for other types of pathogens and biomolecules.

18.
International Journal of Mechanical Sciences ; 238, 2023.
Article in English | Web of Science | ID: covidwho-2179592

ABSTRACT

This research examines on a new class of MEMS inertia mass sensors that are simple, sensitive, and selective in possibly detecting tiny objects. The sensor consists of two beams attached by an end-plate and is mounted on an electrostatically actuated shallow micro-arch. The presence of the end-plate overcomes the shortcoming of building inertia mass sensors using in-plane beam resonators. It gives more room to deposit detector material and, therefore, controls and mobilizes the quantity of the detector toward sensing a target. The design exploits the bistable behavior, resulting from the combination of the snap-through instability and the nonlinear force to move from one stable equilibrium to another. The transition can be controlled statically or dynamically depending on an operational modes. The eigenvalue problem assessment shows a considerable reduction in the first and third symmetrical resonant frequencies under DC voltage when a few picograms of the object substance are introduced. It is also corroborating that placing the added mass at the center of the end-plate and operating the sensor at vibration mode shape that dominated by the platform are more effective for mass detection through measuring the change in its frequency and bifurcation points. We found that superimposing the excitation signal to a small AC harmonic load, linear dynamic responses show a shift in the neighborhood of the first resonant frequency. On the other hand, increasing the actuation signal, dynamic responses show nonlinear trends offering possibilities to use the proposed design as a bifurcation-based type inertia sensor. This added mass leads to significant shifts at the locations of the bifurcation points compared to those in the absence of the object.

19.
Current Research in Biotechnology ; 4:564-578, 2022.
Article in English | EMBASE | ID: covidwho-2177931

ABSTRACT

Electrochemical biosensors are analytical devices that hold a current across the surface of an electrode on which biological receptors are immobilized. These devices enable the conversion of physio-biochemical reactions by biological molecules into electron movements, so the output can be observed as the flow of charge across the electrode. These biosensing platforms detect changes in the reactive and resistive properties of the electrode surface when an alternating current (AC) or voltage is applied to output signals. Impedance-based electrochemical biosensors have advantages compared with other biosensors, such as high sensitivity, low cost, and ease of operation. In addition to uses as miniature detection tools, biosensors and microfluidics play vital roles in nano-diagnostics. Many sensors have been developed at the nanoscale by exploiting the greater conductivity across the electrodes and improved specificity for biorecognition element-receptor binding in biosensing devices. Several of these sensors have been assessed in trials and emerged as clinical products for detecting and diagnosing diseases, bacteria, viruses, deficiencies, and biofluid malfunctions in the human body. This review summarizes advances in impedance-based biosensors and their working principles and classifications, as well as providing relevant illustrations by focusing on the essential biorecognition elements, receptors, and target molecules during diagnosis. Copyright © 2022 The Authors

20.
Anal Biochem ; : 115046, 2023.
Article in English | PubMed | ID: covidwho-2175673

ABSTRACT

The early diagnosis of coronavirus disease 2019 (COVID-19) is dependent on the specific and sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. Herein, we develop a highly sensitive and specific electrochemical biosensor for SARS-CoV-2 target RNA detection based on the integration of protospacer adjacent motif (PAM)-free cascaded toehold-mediated strand displacement reactions (TSDRs) and CRISPR-Cas12a (PfTSDR-CRISPR). In this study, each target is transformed into multiple DNA substrates with bubble structure in the seed region by the cascaded TSDRs, which can directly hybridize with guide RNA (gRNA) without PAM requirement and then activate CRISPR-Cas12a's trans-cleavage activity. Subsequently, the hairpin DNA modified with methylene blue (MB-HP) is cleaved by activated CRISPR-Cas12a. Therefore, as MB leaves the electrode surface, a decreased current signal is obtained. With the involvement of PAM-free cascaded TSDRs and CRISPR-Cas12a amplification strategy, the PfTSDR-CRISPR-based electrochemical biosensor achieves the detection of target RNA as low as 40 aM. The biosensor has high sequence specificity, reliability and robustness. Thanks to the PAM-free cascaded TSDRs, the biosensor can achieve universal detection of different target RNA without redesigning gRNA sequence of CRISPR-Cas12a. In addition, this biosensor successfully detects SARS-CoV-2 target RNA in complex samples, which highlights its potential for diagnosing COVID-19.

SELECTION OF CITATIONS
SEARCH DETAIL