Chemiresistive Biosensor Research Articles

Development of a TLR1/TLR2-Based Chemiresistive Biosensor for Ultra-Sensitive Gram-Positive Bacterial Detection Using Amine-Terminated Carbon Surfaces

Development of a TLR1/TLR2-Based Chemiresistive Biosensor for Ultra-Sensitive Gram-Positive Bacterial Detection Using Amine-Terminated Carbon Surfaces

Cost-effective chemiresistive biosensor with MWCNT-ZnO nanofibers for early detection of tuberculosis (TB) lipoarabinomannan (LAM) antigen.

Thedevelopment of an affordable chemiresistive biosensor enhanced with a multi-walled carbon nanotube-zinc oxide (MWCNT-ZnO) nanofiber compositeis presented. The sensor leverages the precise interaction between lipoarabinomannan (LAM) tuberculosis (TB) antigens and antibodies to achieve high sensitivity and specificity. The MWCNT-ZnO nanofibers have a larger surface area and better electrical conductivity, which makes it easier for TB antibodies to stick to them. The binding of LAM TB antigens to the fixed Monoclonal Antibody-MBS320597 induces significant resistance changes in the chemiresistive sensor, enabling accurate TB detection. Performance evaluation reveals a linear detection range from 1.0 to 100.0pg/mL in the lower concentration range and up to 6.0ng/mL in the higher concentration range, with a sensitivity of 79.750mApgmL-1cm-2 and a lower limit of detection of 40.54fg/mL. The sensor exhibits a response time of 102s. Featuring rapid response time and high sensitivity, this biosensor is ideally suited for point-of-care (PoC) applications. The incorporation of MWCNT-ZnO nanofibers shows great potential for enhancing the development of sensitive and cost-effective TB diagnostic tools, which could play a crucial role in advancing global TB control and management efforts.

High performance Pt-anchored MoS2 based chemiresistive ascorbic acid sensor

Ascorbic acid (AA), known as vitamin C, is a vital bioactive compound that plays a crucial role in several metabolic processes, including the synthesis of collagen and neurotransmitters, the removal of harmful free radicals, and the uptake of iron by cells in the human intestines. As a result, there is an absolute need for a highly selective, sensitive, and economically viable sensing platform for AA detection. Herein, we demonstrate a Pt-decorated MoS2 for efficient detection of an AA biosensor. MoS2 hollow rectangular structures were synthesized using an easy and inexpensive chemical vapor deposition approach to meet the increasing need for a reliable detection platform. The synthesized MoS2 hollow rectangular structures are characterized through field effect scanning electron microscopy (FESEM), energy-dispersive spectroscopy elemental mapping, Raman spectroscopy, and x-ray photoelectron spectroscopy. We fabricate a chemiresistive biosensor based on Pt-decorated MoS2 that measures AA with great precision and high sensitivity. The experiments were designed to evaluate the response of the Pt-decorated MoS2 biosensor in the presence and absence of AA, and selectivity was evaluated for a variety of biomolecules, and it was observed to be very selective towards AA. The Pt-MoS2 device had a higher response of 125% against 1 mM concentration of AA biomolecules, when compared to that of all other devices and 2.2 times higher than that of the pristine MoS2 device. The outcomes of this study demonstrate the efficacy of Pt-decorated MoS2 as a promising material for AA detection. This research contributes to the ongoing efforts to enhance our capabilities in monitoring and detecting AA, fostering advancements in environmental, biomedical, and industrial applications.

A disposable immunosensor array using cellulose paper assembled chemiresistive biosensor for simultaneous monitoring of mycotoxins AFB1 and FB1

Due to the common contamination of multiple mycotoxins in food, which results in stronger toxicity, it is particularly important to simultaneously test for various mycotoxins for the protection of human health. In this study, a disposable immunosensor array with low-cost was designed and fabricated using cellulose paper, polydimethylsiloxane (PDMS), and semiconducting single-walled carbon nanotubes (s-SWCNTs), which was modified with specific antibodies for mycotoxins AFB1 and FB1 detection. The strategy for fabricating the immunosensor array with two individual channels involved a two-step protocol starting with the form of two kinds of carbon films by depositing single-wall carbon nanotubes (SWCNTs) and s-SWCNTs on the cellulose paper as the conductive wire and sensing element, followed by the assembly of chemiresistive biosensor with SWCNTs strip as the wire and s-SWCNTs as the sensing element. After immobilizing AFB1-bovine serum albumin (AFB1-BSA) and FB1-bovine serum albumin (FB1-BSA) separately on the different sensing regions, the formation of mycotoxin-BSA-antibody immunocomplexes transfers to electrochemical signal, which would change with the different concentrations of free mycotoxins. Under optimal conditions, the immunosensor array achieved a limit of detection (LOD) of 0.46 pg/mL for AFB1 and 0.34 pg/mL for FB1 within a wide dynamic range from 1 pg/mL to 20 ng/mL. Furthermore, the AFB1 and FB1 spiked in the ground corn and wheat extracts were detected with satisfactory recoveries, demonstrating the excellent practicality of this established method for simultaneous detection of mycotoxins.

Facile chemiresistive biosensor functionalized with PANI/GOx and novel green synthesized silver nanoparticles for glucose sensing

This article presents a Glossy Photo-Paper (GPP) based Screen-Printed Chemiresistive Interdigitate Electrode (SPCIDE) for enzymatic glucose sensing. A facile inexpensive screen-printing method was used to print the low sheet resistance Interdigitate Electrodes (IDEs) with graphene as conductive ink on the proposed GPP. The screen-printed IDE was functionalized with Polyaniline (PANI) material by drop-cast technique to create a chemiresistive matrix. Further, for selective sensing of glucose, Glucose Oxidase (GOx) enzymes with Green Synthesized Silver Nanoparticles (GS-AgNPs) were immobilized on the PANI material. The proposed GPP-based SPCIDE sensor was used to detect glucose using amperometric measurements. With a correlation coefficient (R2) of 0.9803 and a lower Limit of Detection (LOD) equal to 198 nM, the proposed SPCIDE glucose sensor displays a linear association between change in current and corresponding glucose concentration in the range of 198 nM to 30 mM. An experimental result shows that the created SPCIDE sensor has a sensitivity of 291.19 µA mM−1 cm−2. The study shows that the proposed method may be used to produce facileGPP-based glucose sensors that are inexpensive, eco-friendly, bio-synthesizable, and biodegradable. This may result in developing a Point-of-Care (PoC) diagnostic kit for glucose testing as needed.

Crumpled graphene induced by commercial Heat-Shrinkable material for chemiresistive biosensors toward cancer biomarker detection

Chemiresistive biosensors have revolutionized the field of biomedical diagnosis owing to the novel properties of graphene layered materials that can enhance their sensitivity. We propose a commercial heat-shrinkable material (polystyrene) induced crumpled graphene for cancer biomarker detection. After heating polystyrene, the thermally induced transformation causes the shrinkage and deformation of graphene, resulting in the graphene structure becoming crumpled and thus increasing the surface area. Low-damage plasma treatment is used to oxidize the surface of crumpled graphene with high controllability, forming the bioactive graphene oxide. The DNA probe is then immobilized on graphene oxide via a chemical covalent-amide bond to facilitate hybridization with the biological target miRNA-21. Because the attachment of the miRNA-21 on the oxidized crumpled graphene alters the conductivity, we measure its electrical resistance change rate as a sensor response. The results demonstrate that the sensor response linearity increases with miRNA-21 concentration (10 nM to 1 pM) with the linearity of 0.988 and the limit of detection of 1.74 pM. The results of the real-time applicability test reveal a very high performance with low interference. Therefore, a crumpled graphene-based chemiresistive biosensor has good sensitivity with valuable selectivity, and its biomarker detection raises the possibility of using these sensors for real-time cancer determination and other screening applications in the future.

A Flexible and Wearable Chemiresistive Biosensor Fabricated by Laser Inducing for Real‐Time Glucose Analysis of Sweat (Adv. Mater. Interfaces 22/2023)

A Flexible and Wearable Chemiresistive Biosensor Fabricated by Laser Inducing for Real‐Time Glucose Analysis of Sweat (Adv. Mater. Interfaces 22/2023)

A Flexible and Wearable Chemiresistive Biosensor Fabricated by Laser Inducing for Real‐Time Glucose Analysis of Sweat

AbstractIn this study, a flexible and wearable chemiresistive biosensor (FWCB) is developed for the real‐time analysis of glucose in sweat on the human skin surface based on a novel detection strategy of p‐type reduced graphene oxide (rGO) sensing film, which met the requirements of rapid, nondestructive testing. The proposed FWCB is fabricated in the form of interdigital electrodes (IEs) made of laser‐induced graphene (LIG) synthesized by the laser inducing of a polyimide (PI) film. Additionally, a semiconducting rGO sensing film modified on the surface of IEs is synthesized by thermal reduction of graphene oxide (GO), which is functionalized with glucose oxidase (GOx) by chemical cross‐linking to obtain GOx/FWCB. Moreover, the key parameters for FWCB fabrication are optimized, and the sensing strategy of the proposed GOx/FWCB is also investigated. The results show that the proposed GOx/FWCB can be used for the detection of glucose in the range of 0.01–3.0 mM with satisfactory selectivity, and the limit of detection (LOD) is calculated to be as low as 0.8 µM (S/N = 3). These dramatic advantages endow the proposed FWCB with broad application prospects in the field of portable, wearable, and real‐time detection of glucose in human sweat for health monitoring.

Tear-based MMP-9 detection: A rapid antigen test for ocular inflammatory disorders using vanadium disulfide nanowires assisted chemi-resistive biosensor

A sensitive, non-invasive, and biomarker detection in tear fluids for inflammation in potentially blinding eye diseases could be of great significance as a rapid diagnostic tool for quick clinical decisions. In this work, we propose a tear-based MMP-9 antigen testing platform using hydrothermally synthesized vanadium disulfide nanowires. Also, various factors contributing to baseline drifts of the chemiresistive sensor including nanowire coverage on the interdigitated microelectrode of the sensor, sensor response duration, and effect of MMP-9 protein in different matrix solutions were identified. The drifts on the sensor baseline due to nanowire coverage on the sensor were corrected using substrate thermal treatment providing a more uniform distribution of nanowires on the electrode which brought the baseline drift to 18% (coefficient of variations, CV = 18%). This biosensor exhibited sub-femto level limits of detection (LODs) of 0.1344 fg/mL (0.4933 fmoL/l) and 0.2746 fg/mL (1.008 fmoL/l) in 10 mM phosphate buffer saline (PBS) and artificial tear solution, respectively. For a practical tear MMP-9 detection, the proposed biosensor response was validated with multiplex ELISA using tear samples from five healthy controls which showed excellent precision. This label-free and non-invasive platform can serve as an efficient diagnostic tool for the early detection and monitoring of various ocular inflammatory diseases.

A chemiresistive biosensor for detection of cancer biomarker in biological fluids using CVD-grown bilayer graphene.

A chemiresistive biosensor is described for simple and selective detection of miRNA-21. We developed chemical vapor deposition (CVD) and low-damage plasma treatment (LDPT)-treated bilayer graphene composite of graphene oxide/graphene (GO/GR) for the determination of a reliable biomarker. We have successfully overcome the self-limiting growth mechanism by using CVD method to grow more than one layer of graphene on copper foil. In addition, LDPT can be used to form GO/GR structures for chemiresistive biosensor applications. Due to the direct formation of BLGR (bilayer graphene), the coupling between graphene layers is theoretically superior to that of stacked BLGR, which is also confirmed by the blue shift of the characteristic peak of graphene in Raman spectroscopy. The shift is about double compared with that of stacked BLGR. Based on the results, the limit of detection for the target miRNA-21 was calculated to be 5.20 fM and detection rage is calculated as 100 fM to 10 nM, which is obviously better performance. Compared with previous work, this chemiresistive biosensor has good selectivity, and stability towards detection of miRNA-21. The ability to detect miRNA-21 in different biological fluids was almost identical to that in pH 7.4 phosphate-buffered saline (PBS). Thus, the proposed bilayer GO/GR of modified chemiresistive biosensor may potentially be applied to detect cancer cells in clinical examinations.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00604-022-05463-7.

Isolating Specific vs. Non-Specific Binding Responses in Conducting Polymer Biosensors for Bio-Fingerprinting.

A longstanding challenge for accurate sensing of biomolecules such as proteins concerns specifically detecting a target analyte in a complex sample (e.g., food) without suffering from nonspecific binding or interactions from the target itself or other analytes present in the sample. Every sensor suffers from this fundamental drawback, which limits its sensitivity, specificity, and longevity. Existing efforts to improve signal-to-noise ratio involve introducing additional steps to reduce nonspecific binding, which increases the cost of the sensor. Conducting polymer-based chemiresistive biosensors can be mechanically flexible, are inexpensive, label-free, and capable of detecting specific biomolecules in complex samples without purification steps, making them very versatile. In this paper, a poly (3,4-ethylenedioxyphene) (PEDOT) and poly (3-thiopheneethanol) (3TE) interpenetrating network on polypropylene–cellulose fabric is used as a platform for a chemiresistive biosensor, and the specific and nonspecific binding events are studied using the Biotin/Avidin and Gliadin/G12-specific complementary binding pairs. We observed that specific binding between these pairs results in a negative ΔR with the addition of the analyte and this response increases with increasing analyte concentration. Nonspecific binding was found to have the opposite response, a positive ΔR upon the addition of analyte was seen in nonspecific binding cases. We further demonstrate the ability of the sensor to detect a targeted protein in a dual-protein analyte solution. The machine-learning classifier, random forest, predicted the presence of Biotin with 75% accuracy in dual-analyte solutions. This capability of distinguishing between specific and nonspecific binding can be a step towards solving the problem of false positives or false negatives to which all biosensors are susceptible.

A high sensitive chemiresistive-biosensor based on self-assembly grown GaN porous layer

As 3rd generation semiconductor, GaN material is promising for biosensor application, owing to its excellent chemical stability and high carrier mobility. Herein, GaN porous-layer (GNP) was self-assembly grown on GaN-coated sapphire substrate without doping by using simple low-temperature (LT) growth. The GNP with a pore density as high as ∼2.1 × 103 μm−2 can be realized by optimizing the growth temperature (620 °C) and layer thickness (22.4 nm), and its normalized conductivity can be tuned by simply changing the thickness. The optimized GNP was applied to chemiresistive detection of Cu2+ with a limit of detection (LOD) as low as 8 fM, a fast response speed of 1.5 min, a wide linear range (8 fM∼8 nM) and good repeatability. The LOD was improved 1.25∼106 fold compared with that of previously reported biosensor. The GNP biosensor features high sensitivity, simple structure, integratability, and low-cost. To our knowledge, it is the first time that GaN material was used for chemiresistive biosensor.

Laser-etched grooves for rapid fluid delivery for a paper-based chemiresistive biosensor

Paper-based microfluidic devices are an attractive option for developing low-cost, point-of-care diagnostic tools. To incorporate more complex assays into paper, these devices must become more sophisticated, through the sequential delivery of different liquids or reagents without user intervention. Many flow control strategies focus on slowing the fluid down. However, this can lead to increased assay times and sample loss due to evaporation. We report the use of a CO2 laser to create etched grooves on paper to accelerate wicking speeds in paper-based microfluidic devices. We explored different laser settings to determine the optimal configuration. Our findings showed that simply cutting a slit into the paper created the fastest wicking channels. The slit acted as a macro capillary, allowing fluid to bypass the paper and speed it up. Further studies determined an ideal groove pitch of 0.75 mm (spacing in between grooves) for a paper channel. Additional experiments documented how sealing grooved channels with different adhesives can influence wicking. Overall, sealing the channels with tape made them wick faster. However, sealing methods such as lamination had a negative effect on wicking. Laser-etched grooves were successfully used to design a fluid-handling architecture for a chemiresistive paper-based biosensor. The grooves facilitated rapid, sequential delivery of sample and wash buffer. Human serum albumin spiked in phosphate buffer, artificial urine, and artificial saliva was successfully detected at as low as 15 pM. Etching grooves in paper is a simple process that requires no additional materials or chemicals, allowing single-step fabrication of paper-based microfluidic channels.

A chemiresistive biosensor based on a layered graphene oxide/graphene composite for the sensitive and selective detection of circulating miRNA-21

In this study we developed a uniform, large-area, layered graphene composite of graphene oxide/graphene (GO/G) for the detection of circulating miRNA-21, a reliable biomarker for early cancer diagnosis. We prepared this layered composite of GO/G through low-damage plasma treatment of bilayer G. The top layer of G was oxidized (i.e., atomic layer oxidation) to form a GO layer, which acted as the bio-receptor, while retaining the properties of the bottom layer of G, which acted as an electrical response medium. With this structure, we fabricated a simple chemiresistive biosensor that could detect miRNA-21. The electrical resistance of the sensor varied linearly (R2 = 0.986) with respect to concentrations of the target miRNA-21 in the range from 10 pM to 100 nM in phosphate-buffered saline (PBS); the limit of detection was 14.6 pM. Hall measurements revealed that the mobility and concentration of the hole carriers both decreased upon increasing the target concentration, leading to the measured increase in resistivity of our chemiresistive biosensor. Furthermore, the sensor could discriminate the complementary target miRNA-21 from its single- and four-base-mismatched counterparts and another non-complementary miRNA. The ability to detect miRNA-21 in human serum albumin and bovine serum albumin was almost identical to that in PBS.

Monolayer graphene chemiresistive biosensor for rapid bacteria detection in a microchannel

Bacteria, such as Escherichia coli (E. coli), can cause food poisoning and serious diseases. In fact, E. coli has emerged multiple times as a severe public health concern in recent years. Therefore, it is important to detect bacteria like E. coli in simple, rapid and sensitive approaches. In this study, a gate-free chemiresistive biosensor based on monolayer graphene (MG) is proposed to detect E. coli, thanks to the high sensitivity stemming from the anti-E. coli antibody-coated graphene. The immobilization of the antibodies is performed via streptavidin and biotin conjugation on the graphene surface. Compared to conventional bacterial biosensors, the proposed chemiresistive biosensor captures the E. coli bacteria on the surface of the sensor and performs the detection through electric readouts, other than optical signals. That is the resistance measured in the biosensor increases along with the increase of concentration of the bacteria. To further extend the capabilities of this biosensor and provide a controllable test flow, a microchannel is integrated on the graphene surface. The results show that the developed chemiresistive biosensor is able to detect E. coli in trace concentration down to 12 cfu mL−1, indicating an excellent sensing performance. The proposed monolayer graphene based chemiresistive biosensor clearly manifest its advantages of low-cost, ease of fabrication, portability and good sensitivity, as well as the potential for rapid in-situ bacterial detection.

Detection of a secreted protein biomarker for citrus Huanglongbing using a single-walled carbon nanotubes-based chemiresistive biosensor

Citrus greening, or Huanglongbing (HLB), is currently the most devasting disease of citrus, creating unprecedented crisis for the multibillion-dollar global citrus industry. To-date, there is no effective cure and disease management relies on early detection and removal of infected trees. Thus, it is imperative that accurate, timely, and robust disease detection and diagnosis technologies are available to minimize the spread of disease. This study reports a sensitive and selective label-free biosensor that combines the physical and chemical advantages of carbon nanomaterials like single-walled carbon nanotubes (SWNTs) in a field-effect transistor (FET)/chemiresistor architecture with selective antibodies against Sec-delivered effector 1 (SDE1), a secreted protein biomarker, for the detection of HLB. The biosensor detected SDE1 biomarkers for citrus greening in plant tissue extracts with the dynamic range over three orders of magnitude in the low nanomolar to micromolar concentration range and limit of detection of 5 nM. The study also demonstrated the use of the standard additions assay method with the biosensor to attain a 90-percent signal recovery in concentrated plant tissue extract, allowing for quantitative detection without an external calibration. Adopting the novel detection strategy targeting the secreted protein biomarker, SDE1, addresses some of the challenges faced by current methods of nucleic acid-based assays and symptom-based diagnosis, which have been found prone to false negatives and misdiagnoses, respectively.

A paper-based chemiresistive biosensor employing single-walled carbon nanotubes for low-cost, point-of-care detection

Paper-based biosensors are promising for low-cost diagnostics. However, its widespread use has been hampered due to a lack of sensitive detection methods that can be easily implemented on paper substrates. On the other hand, single-walled carbon nanotubes (SWNTs) -based chemiresistive biosensors are gaining popularity as label-free, highly sensitive biosensors. However, traditional SWNT-based chemiresistors need to be more affordable for use in resource-limited settings. In this study, we report fabrication, optimization and analytical characterization of a chemiresistive biosensor on paper for label-free immunosensing. We synthesized a water-based ink using pyrene carboxylic acid (PCA) through non-covalent π-π stacking interaction between PCA and SWNTs. The PCA/SWNTs ink concentration can reach ~4 mg mL−1 and was stable at room temperature for one month. We introduced a combination of wax printing and vacuum filtration to fabricate the hydrophilic channels and the well-defined PCA/SWNTs ink deposition on paper in a facile manner requiring no additional masks or stencils. Specific antibodies were then functionalized on the PCA/SWNTs. Quantitative and selective detection of human serum albumin (HSA) is demonstrated with a limit of detection (LOD) of 1 pM. This low LOD is attributed to the porous structure of the paper surface, which can accommodate more SWNTs. Furthermore, the hydroxyl group-containing cellulose fibers help connect the SWNTs into an electrical network. The paper-based chemiresistive biosensor proposed here is easy to fabricate, and designed for rapid, sensitive and selective detection of HSA. This work provides a potential platform for automated, disposable paper-based biosensors with multiplexed detection capability and microfluidic controls.

A multi-walled carbon nanotube-zinc oxide nanofiber based flexible chemiresistive biosensor for malaria biomarker detection.

We report the fabrication of a flexible, lightweight and disposable multi walled carbon nanotube (MWCNT)-zinc oxide (ZnO) nanofiber based chemiresistive biosensor for label free detection of the malaria biomarker, histidine rich protein II (HRP2). The sensing platform is formed by depositing nanofibers in between the source and drain electrodes patterned on a thin, flexible polyethylene terephthalate (PET) substrate. MWCNT-ZnO nanofibers are synthesized via the electrospinning technique followed by a calcination process. This approach creates functional groups on the nanofiber surface that are used for the one step immobilization of HRP2 antibodies without further surface modification. The device exhibits a good sensitivity of 8.29 kΩ g-1 mL and a wide detection range of 10 fg mL-1-10 ng mL-1, and it is specific towards the targeted HRP2 biomarker. To the best of our knowledge, this is the first report on a flexible chemiresistive biosensor explored for the detection of the malaria biomarker and can be extended in the future to several other biomarker detection systems towards smart point-of-care (POC) diagnostics.

Conducting polymer functionalized single-walled carbon nanotube based chemiresistive biosensor for the detection of human cardiac myoglobin

We report the fabrication of a single-walled carbon nanotube (SWNT) based ultrasensitive label-free chemiresistive biosensor for the detection of human cardiac biomarker, myoglobin (Ag-cMb). Poly(pyrrole-co-pyrrolepropylic acid) with pendant carboxyl groups was electrochemically deposited on electrophoretically aligned SWNT channel, as a conducting linker, for biomolecular immobilization of highly specific cardiac myoglobin antibody. The device was characterized by scanning electron microscopy, source-drain current-voltage (I-V), and charge-transfer characteristic studies. The device exhibited a linear response with a change in conductance in SWNT channel towards the target, Ag-cMb, over the concentration range of 1.0 to 1000 ng ml−1 with a sensitivity of ∼118% per decade with high specificity.

Label-free detection of cardiac troponin-I using gold nanoparticles functionalized single-walled carbon nanotubes based chemiresistive biosensor

We report a specific and ultrasensitive, label-free chemiresistive biosensor based on mercaptopropionic acid capped gold nanoparticles (GNP) functionalized single walled carbon nanotube (SWNT) hybrid for the detection of cardiac specific biomarker troponin-I (cTnI). GNPs were attached to SWNTs through a molecular linker 1-pyrenemethylamine. The highly specific cTnI antibody was covalently immobilized on GNPs through capping agent using carbodiimide coupling reaction. The cTnI interaction to its corresponding antibody was studied with respect to changes in conductance in SWNTs channel, and a detailed field-effect transistor characteristic was delineated. The device exhibited a linear response to cTnI from 0.01 to 10 ng ml−1.