scholarly journals Label-Free Electrochemical Sensor for Rapid Bacterial Pathogen Detection Using Vancomycin-Modified Highly Branched Polymers

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1872
Author(s):  
Holger Schulze ◽  
Harry Wilson ◽  
Ines Cara ◽  
Steven Carter ◽  
Edward N. Dyson ◽  
...  
Keyword(s):  
Pathogen Detection ◽  
Electrochemical Impedance ◽  
Point Of Care ◽  
Branched Polymers ◽  
Label Free ◽  
Conformation Change ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Staphylococcus Carnosus ◽  
Label Free Detection

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.

scholarly journals Microfluidic Impedance Biosensor Chips Using Sensing Layers Based on DNA-Based Self-Assembled Monolayers for Label-Free Detection of Proteins

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 80
Author(s):  
Khaled Alsabbagh ◽  
Tim Hornung ◽  
Achim Voigt ◽  
Sahba Sadir ◽  
Taleieh Rajabi ◽  
...  
Keyword(s):  
Troponin I ◽  
Electrochemical Impedance ◽  
Specific Binding ◽  
Self Assembled Monolayers ◽  
Significant Shift ◽  
Label Free ◽  
Label Free Detection ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Biosensor Chip

A microfluidic chip for electrochemical impedance spectroscopy (EIS) is presented as bio-sensor for label-free detection of proteins by using the example of cardiac troponin I. Troponin I is one of the most specific diagnostic serum biomarkers for myocardial infarction. The microfluidic impedance biosensor chip presented here consists of a microscope glass slide serving as base plate, sputtered electrodes, and a polydimethylsiloxane (PDMS) microchannel. Electrode functionalization protocols were developed considering a possible charge transfer through the sensing layer, in addition to analyte-specific binding by corresponding antibodies and reduction of nonspecific protein adsorption to prevent false-positive signals. Reagents tested for self-assembled monolayers (SAMs) on gold electrodes included thiolated hydrocarbons and thiolated oligonucleotides, where SAMs based on the latter showed a better performance. The corresponding antibody was covalently coupled on the SAM using carbodiimide chemistry. Sampling and measurement took only a few minutes. Application of a human serum albumin (HSA) sample, 1000 ng/mL, led to negligible impedance changes, while application of a troponin I sample, 1 ng/mL, led to a significant shift in the Nyquist plot. The results are promising regarding specific detection of clinically relevant concentrations of biomarkers, such as cardiac markers, with the newly developed microfluidic impedance biosensor chip.

scholarly journals Nitrocellulose-bound achromopeptidase for point-of-care nucleic acid tests

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Georgios Chondrogiannis ◽  
Shirin Khaliliazar ◽  
Anna Toldrà ◽  
Pedro Réu ◽  
Mahiar M. Hamedi
Keyword(s):  
Nucleic Acid ◽  
Sample Preparation ◽  
Point Of Care ◽  
Dna Amplification ◽  
Recombinase Polymerase Amplification ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Enzymatic Function ◽  
Modern Biotechnology ◽  
Nucleic Acid Tests

AbstractEnzymes are the cornerstone of modern biotechnology. Achromopeptidase (ACP) is a well-known enzyme that hydrolyzes a number of proteins, notably proteins on the surface of Gram-positive bacteria. It is therefore used for sample preparation in nucleic acid tests. However, ACP inhibits DNA amplification which makes its integration difficult. Heat is commonly used to inactivate ACP, but it can be challenging to integrate heating into point-of-care devices. Here, we use recombinase polymerase amplification (RPA) together with ACP, and show that when ACP is immobilized on nitrocellulose paper, it retains its enzymatic function and can easily and rapidly be activated using agitation. The nitrocellulose-bound ACP does, however, not leak into the solution, preventing the need for deactivation through heat or by other means. Nitrocellulose-bound ACP thus opens new possibilities for paper-based Point-of-Care (POC) devices.

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

MRS Advances ◽  
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.

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

2D Materials ◽  
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

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

2020 ◽  
Vol 11 ◽  
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.

scholarly journals Impedimetric Immunosensor Utilizing Polyaniline/Gold Nanocomposite-Modified Screen-Printed Electrodes for Early Detection of Chronic Kidney Disease

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3990 ◽  
Author(s):  
Muhammad Omar Shaikh ◽  
Boyanagunta Srikanth ◽  
Pei-Yu Zhu ◽  
Cheng-Hsin Chuang
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Early Detection ◽  
Electrochemical Impedance ◽  
High Specificity ◽  
Homogeneous Distribution ◽  
Label Free ◽  
Gold Nanocrystals ◽  
Working Electrode ◽  
Label Free Detection

The presence of small amounts of human serum albumin (HSA) in urine or microalbuminuria (30–300 µg/mL) is a valuable clinical biomarker for the early detection of chronic kidney disease (CKD). Herein, we report on the development of an inexpensive and disposable immunosensor for the sensitive, specific, and label-free detection of HSA using electrochemical impedance spectroscopy (EIS). We have utilized a simple one-step screen-printing protocol to fabricate the carbon-based three-electrode system on flexible plastic substrates. To enable efficient antibody immobilization and improved sensitivity, the carbon working electrode was sequentially modified with electropolymerized polyaniline (PANI) and electrodeposited gold nanocrystals (AuNCs). The PANI matrix serves as an interconnected nanostructured scaffold for homogeneous distribution of AuNCs and the resulting PANI/AuNCs nanocomposite synergically improved the immunosensor response. The PANI/AuNCs-modified working electrode surface was characterized using scanning electron microscopy (SEM) and the electrochemical response at each step was analyzed using EIS in a ferri/ferrocyanide redox probe solution. The normalized impedance variation during immunosensing increased linearly with HSA concentration in the range of 3–300 µg/mL and a highly repeatable response was observed for each concentration. Furthermore, the immunosensor displayed high specificity when tested using spiked sample solutions containing different concentrations of actin protein and J82 cell lysate (a complex fluid containing a multitude of interfering proteins). Consequently, these experimental results confirm the feasibility of the proposed immunosensor for early diagnosis and prognosis of CKD at the point of care.

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

Proceedings ◽  
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.

scholarly journals A liquid-crystal-based DNA biosensor for pathogen detection

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Mashooq Khan ◽  
Abdur Rahim Khan ◽  
Jae-Ho Shin ◽  
Soo-Young Park
Keyword(s):  
Liquid Crystal ◽  
Pathogen Detection ◽  
Grid Cell ◽  
High Specificity ◽  
Erwinia Carotovora ◽  
Optical Microscope ◽  
Label Free ◽  
Label Free Detection ◽  
Homeotropic Orientation ◽  
Tem Grid

Abstract A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.

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

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.

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