Electrochemical Biosensor System Research Articles

Fabrication of ultra-sensitive and disposable electrochemical biosensor: Detection of kidney injury molecule-1 protein in urine for diagnosis of kidney injury

This research study indicates the development of the indium tin oxide-polyethylene terephthalate (ITO-PET) coated electrode-based electrochemical biosensor system to sensitively and specifically detect kidney injury molecule-1 (KIM-1), an acute kidney injury (AKI) biomarker. The ITO-PET electrode surface was modified with 3-(Trimethoxysilyl)-1-propanethiol (3-TMESP) silane agent. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and single frequency impedance (SFI) techniques were utilized to examine the interactions between anti-KIM-1 antibody and KIM-1 antigen. The ITO-PET electrode surface was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to analyze the morphological characterization at each electrode development stage. Optimization studies have been conducted to determine the optimal concentrations for detecting the 3-TMESP silane agent, the NHS crosslinker, the anti-KIM-1 antibody, and the optimum incubation period for the anti-KIM-1 antibody and the KIM-1 antigen. Analytical characteristic properties of the developed biosensor, including linear determination range, and the studies of reproducibility, regeneration, repeatability, storage life, and selectivity were investigated. The KIM-1 biosensor system, based on 3-TMESP, has a broad linear range and is capable of providing sensitive measurements between 0.1 fg/mL and 1000 fg/mL. The values of low limits of detection (0.26 fg/mL) and of quantification (0.87 fg/mL) were calculated, highlighting its high sensitivity and precision in detecting KIM-1. In addition, five different commercially purchased human urine samples were tested to validate the practicability of the developed biosensor.

Low noise signal processing for electrochemical biosensor using narrow bandwidth filter

Abstract Biosensor has an important role in several domains, including medical and environmental applications. The improvement of biosensor measurement system therefore offers a better measurement quality. The objective of this work is the development of the signal processing of electrochemical biosensor for advanced analysis and use. The noise of electrochemical sensor is considered rather higher than the other sensor due to many factors such as electrode area, solution velocity, and particle size in solution, which affect adsorption-desorption process. Moreover, the sensor signal processing also makes contribution to noise level. Therefore, it must be reduced and suppressed to obtain better measurement result. In this paper, a bandwidth optimisation method is proposed and used to improve measurement quality. The system is realized with a transimpedance circuit and low-pass and high-pass filter, so that it offers low noise characteristics. The developed proposed system has provided better improvement than the standard electrochemical biosensor system. The noise of the system can be suppressed to be lower up to 14.3% of the standard transimpedance circuit. This development is promising to give better biosensor measurement.

A single-use electrochemical biosensor system for ultrasensitive detection of Aflatoxin B1 in rice, corn, milk, peanut, chili pepper samples

Aflatoxin B1, a common food contaminant in peanuts and corn and a genotoxic carcinogen in humans poses a significant risk for hepatocellular carcinoma, making its detection crucial; this study aims to develop a label-free electrochemical biosensor using a disposable indium tin oxide polyethylene terephthalate (ITO-PET) electrode modified with 3-Aminopropyltriethoxysilane for detecting Aflatoxin B1 in real food samples. Initially, optimization steps for the proposed biosensor were conducted using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. Characterization steps such as storage capacity, regeneration, and single frequency impedance (SFI) were completed for the proposed disposable biosensor after the optimization steps. The electrochemical biosensor, based on AFB1, exhibited excellent repeatability and reproducibility. It had a broad dynamic detection range from 0.1 fg/mL to 500 fg/mL, with low limits of detection (LOD) and quantitation (LOQ) at 0.19 fg/mL and 0.65 fg/mL, respectively. Finally, the proposed AFB1-based biosensor system was applied to real food samples (rice, chili pepper, milk, corn, and peanuts) for testing and validation.

An electrochemical biosensor with homogeneous dual amplification strategy for sensitive analysis of Pb2+

Herein, a homogeneous double amplified electrochemical biosensing system was designed on the basis of rolling circle amplification (RCA) and DNAzyme-assisted Pb2+ recycling amplification with the assistance of the signal molecule methylene blue (MB), which was used for highly sensitive analysis of Pb2+. In comparison with the conventional electrochemical biosensor, the homogeneous strategy adopted in this work can avoid the complex electrode modification and immobilization processes, and address the issues of the large steric hindrance and the restricted probe freedom on the sensing interface, thus achieving high recognition efficiency between recognition unit and target molecule as well as excellent detection performance of biosensor. In addition, the double amplified method assembling RCA and DNAzyme-assisted Pb2+ recycling amplification can convert a handful of target Pb2+ into abundant signal molecule MB, which would lead to the double amplification of output signal and the significantly enhanced detection sensitivity. Taking advantages of homogeneous dual amplification strategy, the constructed electrochemical biosensor for Pb2+ analysis emerged a good linear range of 50 fM to 500 nM and a detection limit of 16.7 fM with significant selectivity and desirable stability. Impressively, the result presented herein comprise a valuable reference for establishing homogeneous multiple amplification model and constructing innovative biosensing system for sensitive detection of heavy metal ions.

Immobilization-free and label-free electrochemical DNA biosensing based on target-stimulated release of redox reporter and its catalytic redox recycling

Herein, we demonstrate a simple, homogenous and label-free electrochemical biosensing system for sensitive nucleic acid detection based on target-responsive porous materials and nuclease-triggered target recycling amplification. The Fe(CN)63− reporter was firstly sealed into the pores of Fe3O4 nanoparticles by probe DNA. Target DNA recognition triggered the controllable release of Fe(CN)63− for the redox reaction with the electron mediator of methylene blue enriched in the dodecanethiol assembled electrode and thereby generating electrochemical signal. The exonuclease III (Exo III)-assisted target recycling and the catalytic redox recycling between Fe(CN)63− and methylene blue contributed for the enhanced signal response toward target recognition. The low detection limit toward target was obtained as 478 fM and 1.6 pM, respectively, by square wave voltammetry and cyclic voltammetry methods. It also possessed a well-discrimination ability toward mismatched strands and high tolerance to complex sample matrix. The coupling of bio-gated porous nanoparticles, nuclease-assisted target amplification and catalytic redox recycling afforded the sensing system with well-controllable signal responses, sensitive and selective DNA detection, and good stability, reusability and reproducibility. It thus opens a new avenue toward the development of simple but sensitive electrochemical biosensing platform.

Electrochemical aptasensor for ultrasensitive cadmium detection through hybridization chain-amplified reaction

Detection of cadmium ion (Cd2+) is of great necessity in safeguarding public health by providing accurate information about its presence in food matrices. A signal amplification electrochemical biosensor system with DNA cascade reaction was designed for ultrasensitive determination of Cd2+, in which in-situ synthesized Ag nanoclusters (Ag NCs) were identified as signal reporters. The highly conductive electrode with large active area, produced by gold deposition on the screen-printed electrodes (SPE), was regarded as an electrochemical platform. Cd2+ aptamer (Apt) was immobilized on the Au NPs modified SPE (Au-SPE) through the Au-S bound to capture Cd2+ by conformational change. Meanwhile, the unoccupied Apt was able to be paired with H1 and H2 by base complementation to accelerate the hybridization chain reaction (HCR) cascade, and the in-situ synthesis of Ag NCs on cytosine-rich sequence of H1 to achieve the quantification of Cd2+ according to the linear sweep voltammetry (LSV). The constructed electrochemical aptasensor exhibited a linear range from 0.1 ng/mL to 100 ng/mL, and the detection limit was 0.088 ng/mL for Cd2+ under optimal conditions. This HCR-based electrochemical aptasensor allowed practical application to tea and vegetable samples with satisfactory accuracy, confirming its promising application for rapid detection of targets in complex systems. Therefore, this platform holds promise for the rapid detection of heavy metals.

Construction of a label-free electrochemical biosensing system utilizing Fe3O4/α-Fe2O3@Au with magnetic-induced self-assembly for the detection of EGFR glycoprotein

A label-free electrochemical biosensing system was developed for the sensitive detection of epidermal growth factor receptor (EGFR), which was frequently overexpressed in lung cancer, breast cancer, and glioblastoma. Magnetic Fe3O4/α-Fe2O3@Au nanocomposites were utilized as the signal amplifiers and for the immobilization matrix of specific probes (ssDNA-APT) in the biosensors. The Fe3O4/α-Fe2O3@Au/ssDNA-APT biosensors were formed through Au–S binding on this matrix and were immobilized onto a magnetic glassy carbon electrode (MGCE) using magnetic-induced self-assembly. The performance of the EGFR detection system was verified using differential pulse voltammetry (DPV). The system exhibited a wide linear range from 0.1 ng/mL to 1000 ng/mL (R2 = 0.9947), with a limit of detection (LOD) of 0.18 ng/mL. Furthermore, the repeatability, stability, selectivity, and ability for real sample analysis were investigated. With its simplicity and reliability, this biosensing system has the potential to be developed as a valuable tool in clinical EGFR detection, offering a promising candidate for point-of-care (POC) testing.

Aggregation-induced signal amplification strategy based on peptide self-assembly for ultrasensitive electrochemical detection of melanoma biomarker

The detection of melanoma circulating biomarker in liquid biopsies is current under evaluation for being potentially utilized for earlier cancer diagnosis and its metastasis. Herein, we developed a non-invasive electrochemical approach for ultrasensitive detection of the S100B, serving as a potential promising blood circulating biomarker of melanoma, based on an aggregation-induced signal amplification (AISA) strategy via in-situ peptide self-assembly. The fundamental principle of this assay is that the designed amphiphilic peptides (C16-Pep-Fc), fulfilling multiple functions, feature both a recognition region for specific binding to S100B and an aggregation (self-assembly) region for the formation of peptide nanomicelles under mild conditions. The C16 tails were encapsulated within the hydrophobic core of the aggregates, while the relatively hydrophilic recognition fragment Pep and Fc tag were exposed on the outer surface for subsequent recognition of S100B and signal output. AISA provided remarkable accumulation of electroactive Fc moieties that enabled ultrasensitive S100B detection of as low as 0.02 nM, which was 10-fold lower than un-amplified approach and better than previously reported assays. As a proof-of-concept study, further experiments also highlighted the good reproducibility and stability of AISA and demonstrated its usability when applied to simulated serum samples. Hence, this work not only presented a valuable assay tool for ultrasensitive detecting protein biomarker, but also advocated for the utilization of aggregation-induced signal amplification in electrochemical biosensing system, given its considerable potential for future practical applications.

A portable label-free electrochemical DNA biosensor for rapid detection of Salmonella Typhi.

A highly accurate, rapid, portable, and robust platform for detecting Salmonella enterica serovar Typhi (S. Typhi) is crucial for early-stage diagnosis of typhoid to avert and control the outbreaks of this pathogen, which threaten global public health. This study presents a proof-of-concept for our developed label-free electrochemical DNA biosensor system for S. Typhi detection, which employs a printed circuit board gold electrode (PCBGE), integrated with a portable potentiostat reader. Initially, the functionalized DNA biosensor and target detection were characterized using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) methods using a benchtop potentiostat. Interestingly, the newly developed DNA biosensor can identify target single-stranded DNA concentrations ranging from 10 nM to 20 μM, achieving a detection limit of 7.6 nM within a brief 5 minute timeframe. Under optimal detection conditions, the DNA biosensor exhibits remarkable selectivity, capable of distinguishing a single mismatch base pair from the target single-stranded DNA sequence. We then evaluated the feasibility of the developed DNA biosensor system as a diagnostic tool by detecting S. Typhi in 50 clinical samples using a portable potentiostat reader based on the DPV technique. Remarkably, the developed biosensor can distinctly distinguish between positive and negative samples, indicating that the miniaturised DNA biosensor system is practical for detecting S. Typhi in real biological samples. The developed DNA biosensor device in this work proves to be a promising point-of-care (POC) device for Salmonella detection due to its swift detection time, uncomplicated design, and streamlined workflow detection system.

11-(triethoxysilyl) undecanal agent-based biosensor system using disposable ITO-PET electrode for tumour necrosis factor-alpha detection

In this study, a label-free electrochemical biosensor system based on a disposable indium tin oxide polyethylene terephthalate (ITO-PET) electrode modified with the 11-(triethoxysilyl) undecanal (11-TESU) agent was developed for the detection of tumour necrosis factor-alpha (TNF-α) in serum. The developed biosensor was observed with electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) techniques, square wave voltammetry (SWV) and single frequency impedance (SFI) technique which is utilized for the specific interaction between anti-TNF-α and TNF-α antigen. In addition, scanning electron microscopy was used to look at how the morphology of each ITO-PET surface changed (SEM). All parameters such as 11-TESU concentration, anti-TNF-α concentration and anti-TNF-α incubation time, were optimized. The biosensor system was characterized by measuring its linear determination range, repeatability, reproducibility, reusability, storage stability, and surface coverage. The TNF-αelectrochemical biosensor showed high levels of repeatability and reproducibility as well as a large dynamic range of detection (from 0.03 pg mL-1 to 3 pg mL-1). The LOD and LOQ for the biosensor were extremely low at 1x10-4 pg mL-1 and 5x10-4 pg mL-1, respectively. It was applied to real samples to determine whether the proposed biosensor would be useful in clinical settings.

Highly sensitive and label-free detection of influenza H5N1 viral proteins using affinity peptide and porous BSA/MXene nanocomposite electrode

Influenza viruses are known to cause pandemic flu through inter-human and animal-to-human transmissions. Neuraminidase (NA), which is a surface glycoprotein of both influenza A and B viruses, is a minor immunogenic determinant; however, it has been proposed as an ideal candidate for a real testing. We successfully identified an affinity peptide which is specific to the influenza H5N1 virus NA via phage display technique and observed initially its binding affinities using enzyme-linked immunosorbent assay (ELISA). In addition, four synthetic peptides were chemically synthesized to develop an affinity peptide-based electrochemical biosensing system. Among all peptides tested, INA BP2 was selected as a potential candidate and subjected to square-wave voltammetry (SWV) for evaluating their detection performance. To enhance analytical performance, a three-dimensional porous bovine serum albumin (BSA)–MXene (BSA/MXene) matrix was applied. The surface morphology of the BSA/MXene film-deposited electrode was analyzed using X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Using SWV measurement, the BSA/MXene nanocomposite-based peptide sensor exhibited significant the dissociation constant (Kd = 9.34 ± 1.20 nM) and the limit of detection (LOD, 0.098 nM), resulting in good reproducibility, stability and recovery, even in the presence with spiked human plasma. These results demonstrate an alternative way of new bioanalytical sensing platform for developing more desirable sensitivity in other virus detection.

Self-Assembled Microfiber-Like Biohydrogel for Ultrasensitive Whole-Cell Electrochemical Biosensing in Microdroplets.

A novel microfiber-like biohydrogel was fabricated by a facile approach relying on electroactive bacteria-induced graphene oxide reduction and confined self-assembly in a capillary tube. The microfiber-like biohydrogel (d = ∼1 mm) embedded high-density living cells and activated efficient electron exchange between cells and the conductive graphene network. Further, a miniature whole-cell electrochemical biosensing system was developed and applied for fumarate detection under -0.6 V (vs Ag/AgCl) applied potential. Taking advantage of its small size, high local cell density, and excellent electron exchange, this microfiber-like biohydrogel-based sensing system reached a linear calibration curve (R2 = 0.999) ranging from 1 nM to 10 mM. The limit of detection obtained was 0.60 nM, which was over 1300 times lower than a traditional biosensor for fumarate detection in 0.2 μL microdroplets. This work opened a new dimension for miniature whole-cell electrochemical sensing system design, which provided the possibility for bioelectrochemical detection in small volumes or three-dimensional local detection at high spatial resolutions.

Bipedal DNAzyme walker triggered dual-amplification electrochemical platform for ultrasensitive ratiometric biosensing of microRNA-21

Circulating microRNAs (miRNAs) can be regarded as reliable noninvasive biomarkers in body fluids for the early diagnosis, prognosis, and monitoring of cancers. By combining target triggered bipedal DNAzyme walker cleavage cycling amplification and planar intercalated methylene blue (MB) molecules amplification, a versatile ratiometric electrochemical biosensing system is constructed for miRNAs detection. Using the microRNA-21 (miRNA-21) as a triggered model target from breast cancer cells (MCF-7) and cervical cancer cells (HeLa), the sensitivity and feasibility of the ratiometric biosensing strategy were verified on the basis of decreased streptavidin-conjugated cupric sulfide@platinum (CuS@Pt-SA) nanozyme signal with cleaved Zn2+-dependent DNAzyme walkers as well as enhanced duplex section of MB signal, which were assisted by the modification of high electronic conductivity and specific surface area of metallic WSe2 nanoflowers on the electrode. Hence, the introduced sensing strategy of higher cleavage activity of the bipedal DNAzyme walker cyclic amplification resulted into the remarkable sensitive measurement which had a detection limit of 0.16 fM from 1 fM to 1 nM for miRNA-21. Benefiting from the precise design of the capture Hairpin DNA, this proposed method showed excellent specificity to distinguish miRNA-21 from other miRNAs sequences, in addition to possessing good stability and reproducibility. Thus, this versatility platform can be utilized to sense various miRNAs biomarkers by simple of the redesigning the capture Hairpin DNA, hence presents a great promise in clinical application towards early cancer diagnosis, biological analysis and prognosis.

An electrochemical immunosensor based on graphite paper electrodes for the sensitive detection of creatine kinase in actual samples

• The electrochemical immunosensor designed very stable, low-cost and sensitive method for determination of Creatine Kinase. • CK immunosensor exhibited high analytical performance with a linear range 0.150 pg/mL and low detection limit (0.045 pg/mL). • Disposable graphite paper electrodes were firstly used to detection CK antigen for a novel biosensor system. • The optimization was performed for all fabrication steps of the electrochemical biosensor system. The enzyme creatine kinase (CK) is one of the most well-established biomarkers in cardiovascular disease. For acute myocardial infarction (AMI) diagnosis, CK has a clinical comorbidity rate of 90%. This study has developed a novel electrochemical immunosensor using disposable graphite paper electrodes (GP). The GP electrodes were modified with gold nanoparticles (AuNP) to facilitate CK detection. Afterwards, GP electrodes were covalently immobilized with 6-mercapto-1-hexanol (6-MH), resulting in self-assembled monolayers (SAMs). Then, the electrodes were formed with a 3-Glycidyloxypropyltrimethoxysilane (3-GOPE) agent. Afterwards, the electrodes were immobilized with anti-CK (antibody creatine kinase) protein. In the final immobilization step, BSA (bovine serum albumin) protein was used to block non-covalent interactions. All parameters of the proposed immunosensor were optimized, including concentrations and incubation times. Analytical characteristics such as square wave voltammetry, linear determination range, repeatability, reproducibility, and regeneration of biosensors were determined. All characterization steps were monitored by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV). Moreover, the single frequency impedance (SFI) technique interacted with anti-CK and CK antigens. Furthermore, the proposed immunosensor was characterized using scanning electron microscopy (SEM). The proposed immunosensor exhibited a wide detection range (0.1–50 pg mL −1 ), and low limit of detection (LOD), and a low limit of quantification (LOQ); 0.045 pg mL −1 and 0.171 pg mL −1 , respectively. Finally, the developed biosensor was tried in an actual blood sample, which showed it could be utilized in clinical applications.

Impedimetric CRISPR-dCas9 Based Biosensor System for Sickle Cell Anemia Mutation

Sickle cell anemia is one of the single point mutation diseases with symptoms such as stroke, lethargy, chronic anemia, and increased mortality, and it causes red blood cells to become sickle-shaped. In the study, a biosensor system was developed to detect this mutation quickly and cost-effectively. This biosensor system was prepared by forming a SAM layer with 4-Aminothiophenol (4-ATP) on the gold electrode, and coating it with amino graphene. It was then modified with SG-RNA with the sequence of the target mutation after CRISPR-dCas9 immobilization. The nanomaterial used in the preparation of the biosensor increased the sensitivity of the method by increasing the surface area. The biosensor prepared in this way was optimized and made to perform DNA analysis. As a measurement method, electrochemical impedance spectroscopy (EIS) was used. Electrochemical measurements were carried out in 50 mM pH 7.0 phosphate buffer solution, which includes 5 mM Fe(CN)64- /3- and 10 mM KCl, as redox probe solution by CV and EIS in this redox probe solution. EIS parameters were 10,000–0.05 Hz frequency, 10 mV AC and 180 mV DC potentials, and CV parameters were between - 0.2 to 0.5 V potential, 100 mV/s scan rate for 5 cycles. The DNA measurement time of the biosensor system was determined by the chronoimpedance measurements taken by applying a frequency of 500 Hz under 200 mV DC current. Measurement time of the biosensor was found to be 100 seconds. With the CRISPR-Cas9 based electrochemical biosensor system, which gives faster results compared to the measurement methods in the literature, a linear measurement between 40 pM and 1000 pM with a length of 400 base pairs was taken.

XNA probe and CRISPR/Cas12a-powered flexible fluorescent and electrochemical dual-mode biosensor for sensitive detection of m6A site-specific RNA modification

N6-methyladenosine (m6A) in RNAs is closely related to various biological progresses, but the specific regulatory mechanisms are still unclear. The existing m6A single-base resolution analysis techniques have problems of specificity and sensitivity to be improved, which can hardly meet the urgent needs of basic research and clinical applications. This work proposes a new strategy based on xeno nucleic acid (XNA) probe and CRISPR/Cas12a signal amplification for the sensitive detection of site-specific m6A modifications. According to the difference in the thermodynamic stability of hybridization between XNA probe with m6A-RNA and A-RNA, XNA was designed as a block probe to mediate m6A-RNA specific reverse transcription polymerase chain reaction (MsRT-PCR). Therefore, m6A can be specifically distinguished by converting difficult-to-test m6A modifications into easily detectable dsDNA fragments. Integration of CRISPR/Cas12a technology, skilfully designed sequences of crRNAs targeting m6A site-specific amplification dsDNA. The specificity was significantly improved through dual specific recognition of XNA probe and crRNA. Furthermore, the sensitivity of the assay was also greatly increased by the combined signal amplification of PCR and CRISPR/Cas12a. Additionally, we extend the application of CRISPR/Cas12a to flexible fluorescent and electrochemical biosensing system, which can accurately detect m6A modifications with different ranges of methylation fractions. The analysis results of m6A sites in MALAT1, ACTB and TPT1 further demonstrated the feasibility of the constructed biosensor for the accurate detection of hypomethylated samples in cells. The implementation of this work will provide strong technical support to promote the in-depth research on m6A in disease regulation mechanisms and in vitro molecular diagnosis.

A Versatile Electrochemical Biosensor for the Detection of Circulating MicroRNA toward Non‐Small Cell Lung Cancer Diagnosis (Small 22/2022)

Cancer Diagnostics In article number 2200784, Kun Qian, Jiayi Wang, and co-workers develop a versatile electrochemical biosensing system for circulating miRNA detection by DNAzyme cleavage cycling amplification and hybridization chain reaction amplification. By profiling miRNA in a non-small-cell lung cancer cohort, this designed liquid biopsy strategy shows high efficiency and sensitivity for early diagnosis and prognosis toward clinical use.

Farklı Elektropolimerizasyon Koşulları Kullanılarak Hazırlanan Polianilin ile Elektrokimyasal Biyosensör Geliştirilmesi

Because of its excellent electrochemical properties, extreme redox performance, and ability to mediate the electron transfer between the electrode surface and the reaction site, polyaniline (PANI) is one of the most ideal and well-known conductive polymers for biosensor design. This research developed an electrochemical enzymatic biosensor system with PANI film-coated screen printed electrodes (SPE) using the one-step direct electropolymerization process. PANI electropolymerization was performed in different acidic solutions, and the effects on the electrodeposition of the potential range, potential scan rate, and cycle number are discussed depending on these acidic solutions. The surface morphologies of films prepared with different processes were characterized by usıng the SEM (scanning electron microscopy) technique. A sensitive and selective catechol biosensor was developed by immobilizing the tyrosinase (Tyr) enzyme into PANI film combined with glutaraldehyde as a cross-linking agent. After optimizing the biosensor performance conditions, the developed biosensor measured catechol in green tea samples.

Rapid and label-free detection of Aflatoxin-B1 via microfluidic electrochemical biosensor based on manganese (III) oxide (Mn3O4) synthesized by co-precipitation route at room temperature

Aflatoxin B1 (AFB1) is the most toxic mycotoxin, naturally occurring in food items, and it causes several types of lethal diseases. Therefore, a rapid and convenient detection method for AFB1 is the first step toward overcoming the effect of AFB1. The current work presents the development of an efficient microfluidic electrochemical-based biosensor using tri-manganese tetroxide nanoparticles (Mn3O4 nps) for AFB1 detection. The Mn3O4 nps were synthesized at room temperature through the co-precipitation route. Its phase purity, structural and morphological studies have been characterized through x-ray diffraction, Raman spectroscopy, energy-dispersive x-ray, Fourier transform infrared spectroscopy and transmission electron microscopy. The mask-less UV-lithography was carried out to fabricate the three-electrode chip and microfluidic channel of the microfluidic electrochemical biosensing system. The designed microfluidic immunosensor (BSA/Ab-AFB1/Mn3O4/ITO) was fabricated using the three-electrode chip, microfluidic channel in poly-dimethyl siloxane. The fabricated sensor exhibited the 3.4 μA ml ng−1 cm−2 sensitivity and had the lowest lower detection limit of 0.295 pg ml−1 with the detection range of 1 pg ml−1 to 300 ng ml−1. Additionally, the spiked study was also performed with this immunoelectrode and a recovery rate was obtained of 108.2%.

Smartphone-Based and Miniaturized Electrochemical Biosensing System for L-Lactate Detection

Real-time detection of L-lactate is crucial in monitoring tissue oxygenation and organ metabolism in surgery patients during the perioperative period. Traditional commercial L-lactate detection techniques using bulky and expensive instruments are time-consuming, hindering timely feedback in the operating room. Herein, utilizing the modified screen-printed carbon electrode, a portable and user-friendly smartphone-based electrochemical biosensing system, integrated with a miniaturized potentiostat via wireless transmission, was successfully constructed for bedside detection of L-lactate. It has a wide sensing range from 0.05–10 mM and a low limit of detection (9.1 μM). Bland–Altman analysis shows an acceptable agreement with the values of a mean difference (0.114 ± 0.3482) between results obtained with the commercial blood gas analysis instrument and the developed portable system. Accordingly, the developed portable system exhibits a great potential in point-of-care testing owing to its portability and rapid response in L-lactate detection during perioperative monitoring.