Label-free detection of H1N1 virus for point of care testing

Rapid point of care tests for bacterial infection diagnosis are of great importance to reduce the misuse of antibiotics and burden of antimicrobial resistance. Here, we have successfully combined a new class of non-biological binder molecules with electrochemical impedance spectroscopy (EIS)-based sensor detection for direct, label-free detection of Gram-positive bacteria making use of the specific coil-to-globule conformation change of the vancomycin-modified highly branched polymers immobilized on the surface of gold screen-printed electrodes upon binding to Gram-positive bacteria. Staphylococcus carnosus was detected after just 20 min incubation of the sample solution with the polymer-functionalized electrodes. The polymer conformation change was quantified with two simple 1 min EIS tests before and after incubation with the sample. Tests revealed a concentration dependent signal change within an OD600 range of Staphylococcus carnosus from 0.002 to 0.1 and a clear discrimination between Gram-positive Staphylococcus carnosus and Gram-negative Escherichia coli bacteria. This exhibits a clear advancement in terms of simplified test complexity compared to existing bacteria detection tests. In addition, the polymer-functionalized electrodes showed good storage and operational stability.

Download Full-text

Comparison of DNAzyme activity for the development of an immobilized heme sensor

MRS Advances ◽

10.1557/adv.2017.637 ◽

2018 ◽

Vol 3 (26) ◽

pp. 1491-1496

Author(s):

Natalie Hughes ◽

Nancy Nguyen ◽

Deanna-Kaye Daley ◽

Justin Grennell ◽

Amira Gee ◽

...

Keyword(s):

Self Assembly ◽

Point Of Care ◽

Label Free ◽

Detection Range ◽

Chemical Complexity ◽

Detection Strategy ◽

Detection Approach ◽

Label Free Detection ◽

G Quadruplex ◽

Care Systems

ABSTRACTPoint-of-care systems require highly sensitive, quantitative and selective detection platforms for the real-time multiplexed monitoring of target analytes. To ensure facile development of a sensor, it is preferable for the detection assay to have minimal chemical complexity, contain no wash steps and provide a wide and easily adaptable detection range for multiple targets. Current studies involve label-free detection strategy for relevant clinical molecules such as heme using G-quadruplex based self-assembly. We have explored the measurement of binding and kinetic parameters of various G-quadruplex/heme complexes which are able to self-associate to form a DNAzyme with peroxidase mimicking capabilities and are critical to nucleic acid research. The detection strategy includes immobilizing the G-quadruplex sequences within a polymer matrix to provide a self-assembly based detection approach for heme that could be translated towards other clinically relevant targets.

Download Full-text

Ultrasensitive WSe2 field-effect transistor-based biosensor for label-free detection of cancer in point-of-care applications

2D Materials ◽

10.1088/2053-1583/ac1253 ◽

2021 ◽

Author(s):

Mohammad Mosarof Hossain ◽

Babar Shabbir ◽

Yingjie Wu ◽

Wenzhi Yu ◽

Vaishnavi Krishnamurthi ◽

...

Keyword(s):

Field Effect ◽

Field Effect Transistor ◽

Point Of Care ◽

Label Free ◽

Label Free Detection ◽

Effect Transistor

Download Full-text

Field-Effect Sensors for Virus Detection: From Ebola to SARS-CoV-2 and Plant Viral Enhancers

Frontiers in Plant Science ◽

10.3389/fpls.2020.598103 ◽

2020 ◽

Vol 11 ◽

Cited By ~ 2

Author(s):

Arshak Poghossian ◽

Melanie Jablonski ◽

Denise Molinnus ◽

Christina Wege ◽

Michael J. Schöning

Keyword(s):

Field Effect ◽

Point Of Care ◽

Virus Detection ◽

Fast Response ◽

Plant Viruses ◽

Clinical Samples ◽

Label Free ◽

Label Free Detection ◽

Field Effect Devices ◽

Long Time

Coronavirus disease 2019 (COVID-19) is a novel human infectious disease provoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, no specific vaccines or drugs against COVID-19 are available. Therefore, early diagnosis and treatment are essential in order to slow the virus spread and to contain the disease outbreak. Hence, new diagnostic tests and devices for virus detection in clinical samples that are faster, more accurate and reliable, easier and cost-efficient than existing ones are needed. Due to the small sizes, fast response time, label-free operation without the need for expensive and time-consuming labeling steps, the possibility of real-time and multiplexed measurements, robustness and portability (point-of-care and on-site testing), biosensors based on semiconductor field-effect devices (FEDs) are one of the most attractive platforms for an electrical detection of charged biomolecules and bioparticles by their intrinsic charge. In this review, recent advances and key developments in the field of label-free detection of viruses (including plant viruses) with various types of FEDs are presented. In recent years, however, certain plant viruses have also attracted additional interest for biosensor layouts: Their repetitive protein subunits arranged at nanometric spacing can be employed for coupling functional molecules. If used as adapters on sensor chip surfaces, they allow an efficient immobilization of analyte-specific recognition and detector elements such as antibodies and enzymes at highest surface densities. The display on plant viral bionanoparticles may also lead to long-time stabilization of sensor molecules upon repeated uses and has the potential to increase sensor performance substantially, compared to conventional layouts. This has been demonstrated in different proof-of-concept biosensor devices. Therefore, richly available plant viral particles, non-pathogenic for animals or humans, might gain novel importance if applied in receptor layers of FEDs. These perspectives are explained and discussed with regard to future detection strategies for COVID-19 and related viral diseases.

Download Full-text

Electrochemical DNA Detection Methods to Measure Circulating Tumour DNA for Enhanced Diagnosis and Monitoring of Cancer

Proceedings ◽

10.3390/iecb2020-07067 ◽

2020 ◽

Vol 60 (1) ◽

pp. 15

Author(s):

Bukola Attoye ◽

Matthew Baker ◽

Chantevy Pou ◽

Fiona Thomson ◽

Damion K. Corrigan

Keyword(s):

Point Of Care ◽

Low Cost ◽

Detection Methods ◽

Clinical Samples ◽

Label Free ◽

Ambient Conditions ◽

Liquid Biopsies ◽

Current Time ◽

Electrochemical Approach ◽

Label Free Detection

Liquid biopsies are becoming increasingly important as a potential replacement for existing biopsy procedures which can be invasive, painful and compromised by tumour heterogeneity. This paper reports a simple electrochemical approach tailored towards point-of-care cancer detection and treatment monitoring from biofluids using a label-free detection strategy. The mutations under test were the KRAS G12D and G13D mutations, which are both important in the development and progression of many human cancers and which have a presence that correlates with poor outcomes. These common circulating tumour markers were investigated in clinical samples and amplified by standard and specialist PCR methodologies for subsequent electrochemical detection. Following pre-treatment of the sensor to present a clean surface, DNA probes developed specifically for detection of the KRAS G12D and G13D mutations were immobilized onto low-cost carbon electrodes using diazonium chemistry and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide coupling. Following the functionalisation of the sensor, it was possible to sensitively and specifically detect a mutant KRAS G13D PCR product against a background of wild-type KRAS DNA from the representative cancer sample. Our findings give rise to the basis of a simple and very low-cost system for measuring ctDNA biomarkers in patient samples. The current time to result of the system was 3.5 h with considerable scope for optimisation, and it already compares favourably to the UK National Health Service biopsy service where patients can wait weeks for their result. This paper reports the technical developments we made in the production of consistent carbon surfaces for functionalisation, assay performance data for KRAS G13D and detection of PCR amplicons under ambient conditions.

Download Full-text

Super-Nernstian ion sensitive field-effect transistor exploiting charge screening in WSe2/MoS2 heterostructure

npj 2D Materials and Applications ◽

10.1038/s41699-021-00273-6 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Sooraj Sanjay ◽

Mainul Hossain ◽

Ankit Rao ◽

Navakanta Bhat

Keyword(s):

Field Effect ◽

Field Effect Transistors ◽

Point Of Care ◽

Low Cost ◽

Ph Sensor ◽

Detection Sensitivity ◽

Label Free ◽

Back Gate ◽

Dielectric Thickness ◽

Label Free Detection

AbstractIon-sensitive field-effect transistors (ISFETs) have gained a lot of attention in recent times as compact, low-cost biosensors with fast response time and label-free detection. Dual gate ISFETs have been shown to enhance detection sensitivity beyond the Nernst limit of 59 mV pH−1 when the back gate dielectric is much thicker than the top dielectric. However, the thicker back-dielectric limits its application for ultrascaled point-of-care devices. In this work, we introduce and demonstrate a pH sensor, with WSe2(top)/MoS2(bottom) heterostructure based double gated ISFET. The proposed device is capable of surpassing the Nernst detection limit and uses thin high-k hafnium oxide as the gate oxide. The 2D atomic layered structure, combined with nanometer-thick top and bottom oxides, offers excellent scalability and linear response with a maximum sensitivity of 362 mV pH−1. We have also used technology computer-aided (TCAD) simulations to elucidate the underlying physics, namely back gate electric field screening through channel and interface charges due to the heterointerface. The proposed mechanism is independent of the dielectric thickness that makes miniaturization of these devices easier. We also demonstrate super-Nernstian behavior with the flipped MoS2(top)/WSe2(bottom) heterostructure ISFET. The results open up a new pathway of 2D heterostructure engineering as an excellent option for enhancing ISFET sensitivity beyond the Nernst limit, for the next-generation of label-free biosensors for single-molecular detection and point-of-care diagnostics.

Download Full-text

Compact multichannel spectroscopic label-free biosensor platform for plant diseases point-of-care testing (POCT)

Biophotonics in Point-of-Care ◽

10.1117/12.2553216 ◽

2020 ◽

Author(s):

Jurij Hastanin ◽

Cedric Lenaerts ◽

Patrick Gailly ◽

Frédéric Rabecki ◽

Aline Roobroeck ◽

...

Keyword(s):

Point Of Care ◽

Plant Diseases ◽

Label Free ◽

Point Of Care Testing

Download Full-text

Electrical and Label-Free Detection of T-Cell Activation Against COVID-19: A Method Towards Point-of-Care Monitoring of Immune System

ECS Meeting Abstracts ◽

10.1149/ma2021-01522031mtgabs ◽

2021 ◽

Vol MA2021-01 (52) ◽

pp. 2031-2031

Author(s):

Mohsen Nami ◽

Patrick Han ◽

Douglas Hanlon ◽

Shari Yosinski ◽

Richard Edelson ◽

...

Keyword(s):

Immune System ◽

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Point Of Care ◽

Label Free ◽

Label Free Detection

Download Full-text

Rapid, label-free, and sensitive point-of-care testing of anti-SARS-CoV-2 IgM/IgG using all-fiber Fresnel reflection microfluidic biosensor

Microchimica Acta ◽

10.1007/s00604-021-04911-0 ◽

2021 ◽

Vol 188 (8) ◽

Author(s):

Wenjuan Xu ◽

Jiayao Liu ◽

Dan Song ◽

Chunsheng Li ◽

Anna Zhu ◽

...

Keyword(s):

Point Of Care ◽

Label Free ◽

Fresnel Reflection ◽

Point Of Care Testing ◽

Microfluidic Biosensor

Download Full-text

Surface Potential-Controlled Oscillation in FET-Based Biosensors

Sensors ◽

10.3390/s21061939 ◽

2021 ◽

Vol 21 (6) ◽

pp. 1939 ◽

Cited By ~ 1

Author(s):

Ji Hyun Kim ◽

Seong Jun Park ◽

Jin-Woo Han ◽

Jae-Hyuk Ahn

Keyword(s):

Surface Potential ◽

Threshold Voltage ◽

Oscillation Frequency ◽

Point Of Care ◽

Ring Oscillator ◽

Ph Sensing ◽

Label Free ◽

Point Of Care Testing ◽

Electrical Measurements ◽

Readout Circuits

Field-effect transistor (FET)-based biosensors have garnered significant attention for their label-free electrical detection of charged biomolecules. Whereas conventional output parameters such as threshold voltage and channel current have been widely used for the detection and quantitation of analytes of interest, they require bulky instruments and specialized readout circuits, which often limit point-of-care testing applications. In this study, we demonstrate a simple conversion method that transforms the surface potential into an oscillating signal as an output of the FET-based biosensor. The oscillation frequency is proposed as a parameter for FET-based biosensors owing to its intrinsic advantages of simple and compact implementation of readout circuits as well as high compatibility with neuromorphic applications. An extended-gate biosensor comprising an Al2O3-deposited sensing electrode and a readout transistor is connected to a ring oscillator that generates surface potential-controlled oscillation for pH sensing. Electrical measurement of the oscillation frequency as a function of pH reveals that the oscillation frequency can be used as a sensitive and reliable output parameter in FET-based biosensors for the detection of chemical and biological species. We confirmed that the oscillation frequency is directly correlated with the threshold voltage. For signal amplification, the effects of circuit parameters on pH sensitivity are investigated using different methods, including electrical measurements, analytical calculations, and circuit simulations. An Arduino board to measure the oscillation frequency is integrated with the proposed sensor to enable portable and real-time pH measurement for point-of-care testing applications.

Download Full-text