Broad Linear Detection Range Research Articles

Anisotropic Elastomer Ionomer Composite-Based Strain Sensors: Achieving High Sensitivity and Wide Detection for Human Motion Detection and Wireless Transmission.

Anisotropic strain sensors capable of multidirectional sensing are crucial for advanced sensor applications in human motion detection. However, current anisotropic sensors encounter challenges in achieving a balance among high sensitivity, substantial stretchability, and a wide linear detection range. To address these challenges, a facile freeze-casting strategy was employed to construct oriented filler networks composed of carbon nanotubes and conductive carbon black within a brominated butyl rubber ionomer (iBIIR) matrix. The resulting anisotropic sensor based on the iBIIR composites exhibited distinct gauge factors (GF) in the parallel and vertical directions (GF∥ = 4.91, while GF⊥ = 2.24) and a broad linear detection range over a strain range of 190%. This feature enables the sensor to detect various human activities, including uniaxial pulse, finder bending, elbow bending, and cervical spine movements. Moreover, the ion-cross-linking network within the iBIIR, coupled with strong π-cation interactions between the fillers and iBIIR macromolecules, imparted high strength (12.3 MPa, nearly twice that of pure iBIIR) and an ultrahigh elongation at break (>1800%) to the composites. Furthermore, the sensor exhibited exceptional antibacterial effectiveness, surpassing 99% against both Escherichia coli and Staphylococcus aureus. Notably, the sensor was capable of wireless sensing. It is anticipated that anisotropic sensors will have extensive application prospects in flexible wearable devices.

Label-free and sensitive fluorescent detection of Escherichia coli O157: H7 in milk based on cascade strand displacement amplification and G-quadruplex-thioflavin T

The development of a simple, rapid, sensitive, and accurate method for detecting Escherichia coli O157:H7 in complex matrices is critical for ensuring food safety. In this study, a fluorescent biosensor employing aptamer (Apt) -functionalized magnetic beads and cascade strand displacement amplification (SDA) was devised for the detection of E. coli O157:H7 in milk samples. E. coli O157:H7 is captured by the aptamer, causing the complementary DNA (cDNA) to not bind to the aptamer and to be released into the supernatant. Following magnetic separation, the cDNA present in the supernatant initiates the opening of the hairpin (HP) structures. This enables primers to attach to the opened HP, triggering the initial SDA process, which generates a substantial quantity of double-stranded DNA (dsDNA) and recycles cDNA to open more HP structures. The dsDNA activates a second SDA, producing single-stranded DNA (ssDNA) for template binding and instigating a third SDA process. Triple SDA leads to the production of numerous G-quadruplex sequences and the formation of a G-quadruplex structure in the presence of K+. The inclusion of ThT into the G-quadruplex significantly enhances fluorescence. Under optimal conditions, this approach can detect E. coli O157:H7 at levels as low as 101 CFU/mL in pure cultures within 2.5 h, with a broad linear detection range of 101–106 CFU/mL. This method exhibits remarkable specificity towards the target bacteria over non-target bacteria. Furthermore, the technique has been effectively utilized for the detection of E. coli O157:H7 in milk samples. Notably, the method involves only two main steps, identification and amplification, significantly reducing contamination risks and minimizing operational steps.

A novel molecularly imprinted photoelectrochemical sensor utilizing Ag/SnO2 for the highly sensitive and selective detection of 2,4-dichlorophenoxyacetic acid

The pervasive use of herbicides in agriculture has necessitated the development of sensitive and selective detection methods for environmental monitoring. In this work, a novel photoelectrochemical sensor based on molecular imprinting technology was engineered to specifically detect 2,4-dichlorophenoxyacetic acid (2,4-D) using an Ag/SnO2 composite. The SnO2 was chosen as the photoelectric material due to its abundant surface defects, excellent thermal stability, and high electron carrier density, which are essential for enhanced photoelectrochemical reactions. The introduction of Ag to the SnO2 matrix exploited the surface plasmon resonance effect to bridge its wide band gap, thereby improving the photoelectric conversion efficiency. This Ag/SnO2 composite was then deposited onto an indium tin oxide (ITO) substrate to utilize its high conductivity and optical transparency, followed by the strategic layering of molecularly imprinted polymers (MIPs) that offer selective recognition sites for 2,4-D. To ensure the robustness of the sensor, a Nafion solution was meticulously applied dropwise, which served to immobilize the MIPs/Ag/SnO2 complex on the ITO surface and enhance the sensor's durability. Under optimized conditions, the sensor exhibited a broad linear detection range from 3 × 10-12 to 3 × 10-5 mol/L and a low detection limit of 1.13 × 10-12 mol/L (S/N = 3). The sensor also demonstrated exceptional performance in the analysis of 2,4-D in complex matrices, such as milk, tap water, and beef, highlighting its potential for practical applications in the accurate monitoring of herbicide contamination. These findings affirm the sensor's superior photoelectrochemical properties and introduce an innovative method for the sensitive detection of 2,4-D in environmental and food samples.

Detection of Pseudomonas aeruginosa infection using a sustainable and selective polydopamine-based molecularly imprinted electrochemical sensor

Pyocyanin, a redox-active secondary metabolite produced by Pseudomonas aeruginosa, serves as a crucial virulence factor. Detection and quantification of pyocyanin can aid early diagnosis of infection. A selective and sensitive molecularly imprinted electrochemical sensor was constructed by using a green polymerization technique to deposit an ultrathin polydopamine film on an electrode modified with gold nanoparticles and chitosan. Target recognition was facilitated by specific binding sites within the imprinted polymer matrix that are complementary to the structure of pyocyanin. Various techniques, including cyclic voltammetry, electrochemical impedance spectroscopy, and square wave voltammetry, were employed to characterize the electrochemical behavior of the sensor. We investigated the influence of fabrication components, including chitosan concentration, monomer concentration, electro-polymerization conditions, pH, and rebinding time. Demonstrating a high degree of specificity and sensitivity, the sensor showcased a broad linear detection range of 1–100 µM and a low detection limit of 0.74 µM for pyocyanin. Moreover, the sensor successfully detected pyocyanin in real bacterial culture samples, exhibiting a recovery of the spiked standard ranging from 93 to 103 %. The electrochemical sensor displayed satisfactory stability lasting for at least 5 weeks. We demonstrated the sensor's applicability for clinical measurements by detecting pyocyanin in infected burn wounds using an ex vivo porcine skin model. Leveraging the synergistic advantages of molecularly imprinted polymer and the specific redox window for pyocyanin detection, the electrochemical sensor presents a promising approach for early-stage infection identification, thus contributing to enhanced treatment and more effective healthcare for patients.

Ultrasensitive Flexible Pressure Sensors with Broad Linear Detection Range Enabled by Magnetically Induced Self‐Assembled Parallel Circuit

AbstractFlexible pressure sensors have attracted intensive interest for promising applications in healthcare monitoring and flexible electronic devices. Nonetheless, designing flexible pressure sensors to achieve both ultrahigh sensitivity (>1000 kPa−1) and an extensive linear range (>50 kPa) poses a significant challenge. In this study, a facile magnetic‐facilitated self‐assembly parallel circuit strategy to prepare high‐performance flexible pressure sensors in Nickel particles/polydimethylsiloxane (Ni/PDMS) matrices is proposed. The optimized magnetic‐induced Ni/PDMS piezoresistive sensor (MANPS) exhibits an ultrahigh sensitivity of 3707 kPa−1 over a wide broad linear range (0–80 kPa), and excellent durability with the capability of withstanding 2000 pressure cycles. The MANPS is able to detect a broad range of pressures from pulse to plantar pressures (≈60 kPa), demonstrating great potential for whole‐body healthcare monitoring. Additionally, the sensor is further assembled into an array configuration (2 × 5 pixels) for the assessment of plantar pressure distribution. Importantly, the sensitivity and linear range of the MANPS can be readily adjusted by modifying the mixing ratio of the curing agent, thereby significantly broadening its potential applications.

A label-free fluorescent magnetic dual-aptasensor based on aptamer allosteric regulation of β-lactoglobulin

We presented a label-free fluorescent biosensor based on magnetic dual-aptamer allosteric regulation of β-lactoglobulin (β-LG) detection. The bovine serum albumin (BSA) acted as the bridge to connect amino-modified magnetic beads and aptamer, which synthesized pyramid-type probes (MBAP) with high capture and reduced nonspecific adsorption. Moreover, the original aptamer was tailored and then designed as a bivalent aptamer to fabricate allosteric signal probes (ASP). The ASP can both specifically capture β-LG and output the fluorescence signal. The detection mechanism is as follows. The combination of the dual-aptamer and β-LG triggered the allosteric change, resulting in the release of SYBR Green (SG I) from the allosteric signal probe and change signals. This method exhibits a broad linear detection range from 10 ng/mL to 1 mg/mL and the limit of detection reaches as low as 8.06 ng/mL. This study provides a highly generalizable strategy for protein biomolecular detection via replacing different target aptamers.

Synergistic electrochemical sensing of 2,4-dinitrotoluene via bimetallic nickel-cobalt oxide nanoparticles

This study presents a comprehensive investigation into the synthesis, characterization, and application of an exceptionally sensitive electrochemical sensor designed for the ultrasensitive detection of 2,4-dinitrotoluene (DNT), a notorious explosive compound. The sensor employs bimetallic nickel-cobalt oxide (NiCo2O4) nanoparticles, synthesized through a facile hydrothermal method. Extensive analytical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS), were employed to validate the crystallinity and purity of the NiCo2O4 nanoparticles. These nanoparticles, possessing remarkable properties, form the core of our electrochemical sensor, enabling it to offer heightened sensitivity and selectivity even under ambient conditions. Most notably, this sensor boasts an impressively low limit of detection (LOD) of 18 nM, coupled with a broad linear detection range (LDR) spanning from 10 nM to 100 nM. The sensor exhibits robust sensitivity, excellent selectivity, and an outstandingly low detection threshold, collectively demonstrating its potential for precise and accurate detection of DNT. This research underscores the significant potential of bimetallic oxide nanoparticles, specifically NiCo2O4, in the precise quantification of nitro-aromatic analytes. This study opens up promising avenues for assessing hazardous compounds in complex environmental matrices, thereby contributing to the advancement of electrochemical sensing. Additionally, this novel sensing platform holds substantial promise for enhancing security measures and environmental monitoring through its improved sensitivity and selectivity in the detection of explosives.

P-incorporated CuO/Cu2S heteronanorods as efficient electrocatalysts for the glucose oxidation reaction toward highly sensitive and selective glucose sensing.

Currently, tremendous efforts have been made to explore efficient glucose oxidation electrocatalysts for enzymeless glucose sensors to meet the urgent demands for accurate and fast detection of glucose in the fields of health care and environmental monitoring. In this work, an advanced nanostructured material based on the well-aligned CuO/Cu2S heteronanorods incorporated with P atoms is successfully synthesized on a copper substrate. The as-synthesized material shows high catalytic behavior accompanied by outstanding electrical conductivity. This, combined with the unique morphology of unstacked nanorod arrays, which endow the entire material with a greater number of exposed active sites, make the proposed material act as a highly efficient electrocatalyst for the glucose oxidation reaction. Density functional theory calculations demonstrate that P doping endows P-doped CuO/Cu2S with excellent electrical conductivity and glucose adsorption capability, significantly improving its catalytic performance. As a result, a non-enzymatic glucose sensor fabricated based on our proposed material exhibits a broad linear detection range (0.02-8.2 mM) and a low detection limit (0.95 μM) with a high sensitivity of 2.68 mA mM-1 cm-2 and excellent selectivity.

Nanohybrid nanozyme based colourimetric immunosensor for porcine gelatin

Enzyme mimicking nanomaterials, nanozymes, have gained considerable interest in the scientific community because of their superior properties compared to natural enzymes, including their high stability at extreme conditions, cheaper availability, and ease of synthesis. Herein, we report novel colloidal gold nanoparticles – graphene nanoplatelets – chitosan (CS) with peroxidase mimicking properties used to carry out highly sensitive and selective immunoassay for porcine gelatin detection. The interaction between anti-gelatin antibody conjugated nanozyme with porcine gelatin proteins produced an ultrasensitive immunoassay response in the form of a colourimetric signal directly proportional to the porcine gelatin protein concentration. The nanozyme produced a colourimetric response in the presence of its substrate, 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2), demonstrating its peroxidase mimicking properties. The results revealed that the nanozyme exhibited remarkable selectivity and sensitivity in the assay, detecting proteins at concentrations as low as 86.42 pg/mL. Additionally, the immunosensor demonstrated a broad linear detection range spanning from 200 pg/mL to 2 ng/mL.

A Polyamidoamine-Based Electrochemical Aptasensor for Sensitive Detection of Ochratoxin A.

Sensitive detection of ochratoxin A (OTA) is significant and essential because OTA may pose risks to human and animal health. Here, we developed an electrochemical aptasensor for OTA analysis using polyamidoamine (PAMAM) dendrimers as a signal amplifier. As a carrier, PAMAM has numerous primary amino groups that can be coupled with thiolated complementary strand DNA (cDNA), allowing it to recognize aptamers bound to the surface of horseradish peroxidase (HRP)-modified gold nanoparticles (AuNPs), thereby improving the sensitivity of the aptasensor. When monitoring the positive samples, OTA was captured by the aptamer fixed on the HRP-conjugated AuNP surface by specific recognition, after which the formed OTA-aptamer conjugates were detached from the electrode surface, ultimately decreasing the electrochemical signal monitored by differential pulse voltammetry. The novel aptasensor achieved a broad linear detection range from 5 to 105 ng L-1 with a low detection limit of 0.31 ng L-1. The proposed aptasensor was successfully applied for OTA analysis in red wine, with recovery rates ranging from 94.15 to 106%. Furthermore, the aptasensor also exhibited good specificity and storage stability. Therefore, the devised aptasensor represents a sensitive, practical and reliable tool for monitoring OTA in agricultural products, which can also be adapted to other mycotoxins.

Rapid and sensitive electrochemical detection of oxidized form of glutathione in whole blood samples using Bi-metallic nanocomposites

We report a facile one-pot synthesis of bimetallic nickel-gold (Ni–Au) nanocomposite for ultra-sensitive and selective electrochemical detection of oxidized glutathione (GSSG) by electrochemical deposition on fluorine doped tin oxide (FTO) substrate. The electrodeposition of Ni–Au nanocomposite on FTO was confirmed by various characterization techniques such as field emission scanning electron microscopy (FE-SEM), X-ray diffractometer (XRD) and Fourier transform infra-red (FTIR) spectroscopy. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) was utilized for the electrochemical characterization of glutathione reductase (GR)/Ni–Au/FTO working electrode at each stage of modification. The GR enzyme immobilized on the Ni–Au/FTO working electrode via glutaraldehyde cross-linking exhibited excellent selectivity against GSSG in the presence of nicotinamide adenine dinucleotide phosphate (NADPH). The immobilized GR enzyme breaks down the GSSG to reduced glutathione (GSH) and converting NADPH to NADP+ whereby generating an electron for the electrochemical sensing of GSSG. The synergistic behavior of bimetals and good electro-catalytic property of the fabricated sensor provided a broad linear detection range from 1 fM to 1 μM with a limit of detection (LOD) of 6.8 fM, limit of quantification (LOQ) of 20.41 fM and sensitivity of 0.024 mA/μM/cm2. The interference with other molecules such as dopamine, glycine, ascorbic acid, uric acid and glucose was found to be negligible due to the better selectivity of GR enzyme towards GSSG. The shelf-life and response time of the fabricated electrode was found to be 30 days and 32 s, respectively. The real sample analysis of GSSG in whole blood samples showed average recovery percentage from 95 to 101% which matched well with the standard calibration plot of the fabricated sensor with relative standard deviation (RSD) below 10%.

Highly stable electrochemical sensing platform for the selective determination of pefloxacin in food samples based on a molecularly imprinted-polymer-coated gold nanoparticle/black phosphorus nanocomposite

The overuse of pefloxacin (PEF) leaves residues in foods. Therefore, the development of robust analytical techniques for the selective detection of PEF is of great importance. In this study, a highly stable electrochemical sensing platform has been constructed, using molecularly imprinted polymer (MIP)-coated gold nanoparticle/black phosphorus nanocomposites (BPNS-AuNPs), for the selective detection of PEF. BPNS-AuNPs significantly enhance the black phosphorus (BP) stability and electrochemical activity and offer a larger surface area to accommodate more imprinted sites for selective PEF binding. MIP/BPNS-AuNPs exhibit a broad linear detection range (0.005–10 μM), low detection limit (0.80 nM), and high sensitivity (3.199 μA μM−1). The MIP/BPNS-AuNPs show a high binding affinity for PEF, even in the presence of structural analogs, and maintain stable voltammetric signals for at least 35 d. The MIP sensor exhibits consistent high sensitivity in the detection of PEF in real milk and orange juice samples.

Highly sensitively detection of amine vapors released during shrimp spoilage by fluorescent molecules locked in covalent organic frameworks.

The fluorescent sensors allow sensitive detection of amine vapors for assessing the safety and quality of seafood products. However, high diffusion resistance and insufficient recognition sites usually limit the sensitivity of the sensors. Here, we employed an emulsion-confined assembly strategy to uniform encapsulate fluorescent molecules perylene diimide (PDI) molecules into covalent organic frameworks (COFs) to achieve ultrasensitive detection of amine vapors. The detection mechanism is based on the photoinduced electron transfer from amine to the excited PDI. This method exhibits a broad linear detection range from 8ppb to 800ppm and the limit of detection reaches as low as 1.2ppb. The real-time detection of the amine vapors produced during shrimp spoilage is successfully achieved with excellent performance. This provides a versatile method for the on-demand synthesis of functional materials with high fluorescence properties for the development of chemical sensors via encapsulating different fluorescent molecules into COFs.

B-267 Validation of a New Molecular Test to Quantify Plasma Cytomegalovirus Load

Abstract Background Cytomegalovirus (CMV) is a DNA virus that often causes severe disease in immunosuppressed or immunocompromised patients. With the expanding indications for immune-modulating agents and transplant patients, the number of patients at risk for developing CMV disease is increasing. Test results are used to determine active CMV disease, risk of developing active disease, response to therapy, risk of relapsed infection, and/or appropriate time to discontinue therapy. For this purpose, molecular assays are attractive because of their broad linear range and low limits of detection. CerTest Biotec has developed a quantitative real time PCR assay for the detection and quantification of cytomegalovirus in plasma samples. Methods Plasma-EDTA samples characterized as positive or negative and quantified by IU/ml were selected. The selected samples were collected from both male and female adults (except 1 sample of an infant) between July 2016 and December 2020. Two CE-marked molecular reference assays were used for the comparative analysis: RealStar® CMV PCR Kit 1.0 (Altona), using the CFX96™ Real-Time PCR Detection System (Bio-Rad) and extracted with the QIAamp® MinElute® Virus Spin Kit (QIAGEN); and cobas® CMV (Roche Diagnostics), using the cobas® 8800 system. VIASURE analysis was performed using the following workflow: the automated extraction method MagDEA® Dx SV with magLEAD® 12gC and CFX96™ Real-Time PCR Detection System (Bio-Rad). Results A total of 273 EDTA-plasma clinical samples were analysed, 120 samples were reported as CMV positive samples and quantified and 153 samples were reported as CMV negative samples. Comparative analysis determined >99% sensitivity and specificity. Regarding quantification, all methods obtained a correlation value of R2 ≥ 0.77. Conclusion With this study it was possible to observe that the VIASURE CMV q Real Time PCR Detection Kit present good clinical sensitivity and specificity compared to reference molecular assays results. No false positive results were observed. However, all variables employed on the workflow contribute to final quantification results and therefore should be taken into account as accumulative error in the calculation.

Repurposing of waste ammonium sulfate as S,N-doped carbon quantum dots: A sensitive and selective fluorescent probe for the determination of tetracycline

BackgroundCurrently, many types of pharmaceuticals are used to treat disease and bacterial infections. Tetracycline (TC) is a widely applied human and veterinary medicine. However, the widespread usage and lack of awareness in the management of TC lead to its unavoidable discharge into the environment. The consequences include the proliferation of resistant strains of bacteria and adverse impacts on nontarget organisms and microbial ecosystems, which means that TC is an emerging substance of concern and that it is crucial to develop determination platforms with cost-effective and fast-response features. MethodsCarbon quantum dots (CQDs) have received tremendous attention owing to their great performance in fluorescent probing. In the present work, ammonium sulfate-doped carbon quantum dots (S,NCQDs) are fabricated through a facile hydrothermal synthesis pathway. Significant FindingsThe results illustrate that the S,NCQDs exhibit sensitive determination ability toward tetracycline via a static quenching mechanism and possess several superior features, including a rapid response, good sensitivity and stability, broad linear detection range (1–100 μM), and low LOD value (0.1203 μM), when applied in the determination of TC. Additionally, the application of S,NCQDs valorizes ammonium sulfate waste from semiconductor manufactory waste and has great potential in fluorescence sensing.

Fabrication of Electrochemical Sensor for the Detection of Mg(II) Ions Using CeO2 Microcuboids as an Efficient Electrocatalyst

In human blood serum, the concentration of magnesium ions typically ranges from 0.7 mM to 1.05 mM. However, exceeding the upper limit of 1.05 mM can lead to the condition known as hypermagnesemia. In this regard, a highly sensitive and selective electrochemical sensor for Mg(II) ion detection was successfully fabricated by immobilizing cerium oxide (CeO2) microcuboids, synthesized via microwave radiation method, onto the surface of glassy carbon electrode (GCE). Cyclic voltammetry studies revealed the exceptional electrocatalytic effect of CeO2 microcuboid-modified GC electrode, particularly in relation to the irreversible reduction signal of Mg(II). The microcuboid-like structure of CeO2 microparticles facilitated enhanced adsorption of Mg(II) ion (Γ=2.17×10−7mol cm−2) and electron transfer (ks=8.94 s−1) between the adsorbed Mg(II) ions and GCE. A comprehensive analysis comparing the performance characteristics of amperometry, differential pulse voltammetry, cyclic voltammetry, and square wave voltammetry was conducted. The square wave voltammetry-based Mg(II) sensor exhibited remarkable sensitivity of 2.856 μA mM−1, encompassing a broad linear detection range of 0–3 mM. The detection and quantification limits were impressively low, with values of 19.84 and 66.06 μM, respectively. Remarkably, the developed electrode showed a rapid response time of less than 140 s. Multiple linear regression and partial least squares regression models were employed to establish a mathematical relationship between magnesium ion levels and electrochemical parameters. Notably, the proposed sensor exhibited excellent anti-interferent ability, repeatability, stability, and reproducibility, enabling the fabricated electrode to be used effectively for Mg(II) ion sensing in real-world samples.

Sponge-inspired MXene@CeO2 detector for ultra-sensitive detection of glucose

Non-invasive sweat detectors can monitor the glucose level of diabetes in a painless way. However, most detectors need to collect enough sweat through external exercise or active stimulation, which increases the inconvenience of the user and reduces the applicable population. In this study, we propose an ultra-sensitive biomimetic glucose detector to detect the sweat produced by thermoregulation without additional exercise and stimulation. Inspired by the predator process of sponge in the sea, the sensing material of MXene (Ti3C2Tx) @CeO2 hydrogels employed the “laminae-trestle-laminae” (L-T-L) structure of sponge to adsorb and transport glucose molecules in sweat. CeO2 grafted onto the MXene surface can detect glucose by the catalytic activity of CeO2. The glucose detector with an ultra-low limit of detection (LOD = 0.004 μM), excellent sensitivity (801.27 μA⋅μM−1⋅cm−2), and a broad linear detection range (LDR = 0.01–2.5 μM) can satisfy detection requirements in human sweat after dilution. In real applications, the detector can detect glucose in the sweat of diabetic patients for five consecutive days and detect the glucose content in the daily drinks of patients. Our findings demonstrate the high potential of sponge-inspired MXene@CeO2 glucose detector for routine medical testing.

Electrochemical sensor based on polydopamine-molecularly imprinted polymer for detection of 4-ethylphenyl sulfate “a novel gut metabolite”: Fabrication, characterization, and performance evaluation in human urine

The 4-ethylphenyl sulfate (4-EPS) is considered a well-known gut microbiota derived metabolite that is involved in various human diseases and ailments. Thus, in the present work, an electrochemical sensor was developed using a polydopamine (PDA) based molecularly imprinted polymer (MIP) for the detection of 4-EPS, a gut metabolite using cyclic voltammetry (CV) for the first time. The synthesized PDA-MIP was characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques. The PDA-MIP was drop casted on the surface of screen-printed carbon electrode (SPCE) to fabricate an electrochemical sensor. The developed PDA-MIP/SPCE sensor showed a broad linear detection range of 0.1–300 ng/mL (correlation, R2 = 0.982) with a high sensitivity of 153.88 μA (log ng/mL)−1cm−2 and a low limit of detection (LOD) of 0.018 ng/mL. The selectivity studies were also performed against the possible interfering compounds in human urine. The reproducibility of fabricated PDA-MIP/SPCE shows relative standard deviation (RSD) of 5.34%. For demonstrating the effectiveness of the sensor, the real sample analysis was performed in human urine and it shows the good recovery range of 98.1–121.8% with a RSD of 1.35–13.93%. Therefore, the MIP based electrochemical sensor is economically feasible, which may propose a new diagnostic method for identifying diseases associated with the concentration of 4-EPS in other body fluids.

Effect of Magnesium Chloride in Supporting Electrolyte for Enhancing Sensitive and Selective Electrochemical Sensor: An Approach for Anti-Rheumatic Sulfasalazine Detection

In this work, an electroanalytical evaluation for voltammetric sensing of the anti-rheumatic sulfasalazine (SSZ) at an unmodified screen-printed graphene electrode (SPGE) is demonstrated. By using the differential pulse (DPV) technique, the SSZ produced a well-defined peak of around −0.3 V (vs Ag AgCl−1) in Britton-Robinson (BR) buffer pH 4. Supporting electrolytes, pH, and salts all significantly impact SSZ reduction. Therefore, their impact on the working solutions was assessed. We discovered that using a mixture of Britton–Robinson (BR) buffer with pH 4 and MgCl2 as a supporting electrolyte can enhance SSZ sensitivity by approximately 1.7 times while simultaneously increasing detection selectivity. Under optimal conditions, the proposed assay demonstrated the ultrasensitive determination of SSZ with a broad linear detection range from 0.01 to 100 μM and a low detection limit of 4.7 nM (S/N = 3). To demonstrate the impact of the proposed method, the sensor has been successfully applied for the quantitative determination of SSZ in pharmaceutical, urine, and artificial serum sample. Therefore, this approach could offer simplicity, and rapidity, and serve as an alternative to the SSZ detection in practical applications.

Biocompatible epoxysilane substituted polymer-based nano biosensing platform for label-free detection of cancer biomarker SP17 in patient serum samples

Herein, we report the results of the studies relating to developing a simple, sensitive, cost-effective, and disposable electrochemical-based label-free immunosensor for real-time detection of a new cancer biomarker, sperm protein-17 (SP17), in complex serum samples. An indium tin oxide (ITO) coated glass substrate modified with self-assembled monolayers (SAMs) of 3-glycidoxypropyltrimethoxysilane (GPTMS) was functionalized via covalent immobilization of monoclonal anti-SP17 antibodies using EDC(1-(3-(dimethylamine)-propyl)-3-ethylcarbodiimide hydrochloride) - NHS (N-hydroxy succinimide) chemistry. The developed immunosensor platform (BSA/anti-SP17/GPTMS@SAMs/ITO) was characterized via scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA), Fourier transform infrared (FT-IR) spectroscopic, and electrochemical techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) techniques. The fabricated BSA/anti-SP17/GPTMS@SAMs/ITO immunoelectrode platform was used to measure changes in the magnitude of the current of the electrodes through an electrochemical CV and DPV technique. A calibration curve between current and SP17 concentrations exhibited a broad linear detection range of (100–6000 & 50–5500 pg mL−1), with enhanced sensitivity (0.047 & 0.024 μA pg mL−1 cm−2), limit of detection (LOD) and limit of quantification (LOQ) of 47.57 & 142.9 pg mL−1 and 158.58 & 476.3 pg mL−1, by CV and DPV technique, respectively with a rapid response time of 15 min. It possessed exceptional repeatability, outstanding reproducibility, five-time reusability, and high stability. The biosensor's performance was evaluated in human serum samples, giving satisfactory findings obtained via the commercially available enzyme-linked immunosorbent assay (ELISA) technique, proving the clinical applicability for early diagnosis of cancer patients. Moreover, various in vitro studies in murine fibroblast cell line L929 have been performed to assess the cytotoxicity of GPTMS. The results demonstrated that GPTMS has excellent biocompatibility and can be used for biosensor fabrication.