Surface Of Screen-printed Carbon Electrode Research Articles

Development of Multiwalled Carbon Nanotube-Based Immunobiosensor for the Detection of Bluetongue Virus.

Bluetongue (BT) disease is a noncontagious disease of domestic and wild ruminants (mainly sheep, cattle, deer) caused by the bluetongue virus (BTV) which is an orbivirus of the Reoviridae family and transmitted by vector Culicoides biting midges. It is a reportable disease of considerable socioeconomic concern and of major importance for the international trade of animals and animal products. Conventional diagnostic methods, such as virus propagation and isolation, immunoassays and also various molecular methods have been developed for the detection of the BTV. Here, we present a novel, rapid and pen-side test for the detection of BTV using multiwalled carbon nanotube (MWCNTs) based immunosensor. Though it is not reported yet. The MWCNTs were prepared, characterized and functionalized with carboxyl group. Viral antibodies were conjugated successfully with functionalized MWCNTs and coated on screen printed carbon electrode (SPCE). These SPCE were evaluated by using electrochemical sensor with an antigen specific to BTV antibodies, resulted in the self-assembled layer of antigen-antibody on the surface of SPCE. The approach described in the present study is a prototype for the development of simple and economic diagnostic tool which will provide the routine screening of BT disease at the door of farmers, thereby increasing the income of farmers by decreasing the cost of diagnosis.

Multichannel Immunosensor Platform for the Rapid Detection of SARS-CoV-2 and Influenza A(H1N1) Virus.

The coronavirus disease 2019 (COVID-19) can present a similar syndrome to an influenza infection, which may complicate diagnosis and clinical management of these two important respiratory infectious diseases, especially during the peak season of influenza. A rapid and convenient point-of-care test (POCT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza virus is of great importance for prompt and efficient control of these respiratory epidemics. Herein, a multichannel electrochemical immunoassay (MEIA) platform was developed based on a disposable screen-printed carbon electrode (SPCE) array for the on-site detection of SARS-CoV-2 and A(H1N1). The developed MEIA was constructed with eight channels and allowed rapid detection on a single array. On the SPCE surface, monoclonal antibodies against influenza A(H1N1) hemagglutinin (HA) protein or SARS-CoV-2 spike protein were coated to capture the target antigens, which then interacted with a horseradish peroxidase (HRP)-labeled detection antibody to form an immuno-sandwich complex. The results showed that the MEIA exhibited a broader linear range than ELISA and comparable sensitivity for A(H1N1) HA and SARS-CoV-2 spike protein. The detection results on 79 clinical samples for A(H1N1) suggested that the proposed MEIA platform showed comparable results with ELISA in sensitivity (with a positive rate of 100% for positive samples) but higher specificity, with a false-positive rate of 5.4% for negative samples versus that of 40.5% with ELISA. Thus, it offers great potential for the on-the-spot differential diagnosis of infected patients, which would significantly benefit the efficient control and prevent the spread of these infectious diseases in communities or resource-limited regions in the future.

The Ultra-sensitive Electrochemical Detection of As(III) in Ground Water Using Disposable L-cysteine/Lipoic Acid Functionalised Gold Nanoparticle Modified Screen-Printed Electrodes

An ultrasensitive electrochemical sensor to detect arsenic (III), a highly toxic heavy metal ion, has been successfully developed. The sensing platform composed of L-cysteine (Lcyst) molecules conjugated to reduced lipoic acid (rLA) capped gold nanoparticles and exhibited an indirect band gap energy (Eg) of 1.96 eV. This is a characteristic of a semiconducting material; metals and semiconducting nanomaterials possess good electrochemical properties due to their trivial band gap energies. Surface ligation of the gold nanoparticles with rLA and Lcyst did not only prevent the nanoparticle agglomeration but also improved the susceptibility of the sensor to bind efficiently to heavy metal ions of interest. The electrochemical properties of the sensing platform were demonstrated by a reversible redox electron transfer reaction of the gold oxides due to the presence of gold nanoparticle clusters on the screen-printed carbon electrode surface. The sensor parameters such as the scan rate, pH and the deposition potential were optimised. The sensor was capable of detecting the arsenic (III) ions at the formal peak potential (Epa°′) of −0.307 ± 0.02 V. Subsequently, the sensor demonstrated a low limit of detection with the magnitude of 3 ppb (i.e. 3SD/SLOPE). The dynamic linear range of the developed sensing platform was between 3 and 25 ppb. The sensor was used to detect As(III) in ground water and demonstrated excellent recoveries in spiked samples. The AuNP-rLA-Lcyst sensing platform fabricated for the detection of As(III) heavy metal ion using the square-wave anodic stripping voltammetry.

Anticipating metastasis through electrochemical immunosensing of tumor hypoxia biomarkers.

Metastasis is responsible for about 90% of cancer-associated deaths. In the context of solid tumors, the low oxygen concentration in the tumor microenvironment (hypoxia) is one of the key factors contributing to metastasis. Tumor cells adapt to these conditions by overexpressing certain proteins such as programmed death ligand 1 (PD-L1) and hypoxia-inducible factor 1 alpha (HIF-1α). However, the determination of these tumor hypoxia markers that can be used to follow-up tumor progression and improve the efficiency of therapies has been scarcely addressed using electrochemical biosensors. In this work, we report the first electrochemical bioplatform for the determination of PD-L1 as well as the first one allowing its simultaneous determination with HIF-1α. The target proteins were captured and enzymatically labeled on magnetic microbeads and amperometric detection was undertaken on the surface of screen-printed dual carbon electrodes using the hydrogen peroxide/peroxidase/hydroquinone system. Sandwich immunoassays were implemented for both the HIF-1α and PD-L1 sensors and the analytical characteristics were evaluated providing LOD values of 86 and 279pg mL-1 for the amperometric determination of PD-L1 and HIF-1α standards, respectively. The developed electrochemical immunoplatforms are competitive versus the only electrochemical immunosensor reported for the determination of HIF-1α and the "gold standard" ELISA methodology for the single determination of both proteins in terms of assay time, compatibility with the simultaneous determination of both proteins making their use suitable for untrained users at the point of attention. The dual amperometric immunosensor was applied to the simultaneous determination of HIF-1α and PD-L1 in cancer cell lysates. The analyses lasted only 2h and just 0.5μg of the sample was required.

Simple pre-treatment by low-level oxygen plasma activates screen-printed carbon electrode: Potential for mass production

Screen-printed carbon electrode (SPCE) contains excessive binder which covers the graphite electrode to affect SPCE performance. Oxygen plasma treatment has the potential to remove the binder effectively to enhance electrochemical activity. However, neither the mechanism of this enhancement nor the impact on reference and auxiliary electrodes is clear. To this end, SPCEs were subject to plasma treatment as a whole, followed by scanning electron microcopy and X-ray photoelectron spectroscopy assays to investigate topological and chemical variations on the SPCE surface. Electrochemical performance of plasma-treated SPCEs is dependent primarily on the plasma power, not the duration of treatment. Lower power (50 – 100 W) facilitated binder removal and exposure of both the edge and micro-edge planes of the graphite grains, resulting in significantly improved electrochemical sensitivity of SPCE. However, higher power (200 – 300 W) triggered a coating process due to re-deposition of etched binder to cover up both the basal and edge planes of the graphite grains, resulting in poorer performance of SPCE. Under optimized treatment conditions, SPCE displayed excellent intra-electrode repeatability, inter-electrode reproducibility, and improved electroactivity with no known negative impact from the oxidation of silver reference electrode, demonstrating that oxygen plasma pre-treatment holds potential for mass production of SPCE.

Label-Free and Sensitive Determination of Cadmium Ions Using a Ti-Modified Co3O4-Based Electrochemical Aptasensor.

The current work demonstrates an electrochemical aptasensor for sensitive determination of Cd2+ based on the Ti-modified Co3O4 nanoparticles. In this unlabeled system, Ti-modified Co3O4 nanoparticles act as current signal amplifiers modified on the screen-printed carbon electrode (SPCE) surface, while the derivative aptamer of Cd2+ works as a target recognizer. In addition, the sensing is based on the increase in electrochemical probe thionine current signal due to the binding of aptamer to Cd2+ via specific recognition. In the current study, key parameters, including aptamer concentration, pH, and incubation time were optimized, respectively, to ensure sensing performance. Cyclic voltammetry was used not only to characterize each preparation and optimization step, but also to profile the bindings of aptamer to Cd2+. Under optimal conditions, Cd2+ can be determined in a linear range of 0.20 to 15 ng/mL, with a detection limit of 0.49 ng/mL, significantly below the maximum concentration limit set by the U.S. Environmental Protection Agency. Based on comparative analysis and the results of recovery test with real samples, this simple, label-free but highly selective method has considerable potential and thus can be used as an in-situ environmental monitoring platform for Cd2+ testing.

Controlled diazonium electrodeposition towards a biosensor for C-reactive protein

Electrografting of aryldiazonium species is useful for linkage between electrochemical transducer surface and biosensor recognition elements. However, the process proceeds uncontrollably to form branched/multilayer growth. This paper reports harnessing steric hindrance for controlled growth of aryldiazonium coupling agent during electrografting to screen-printed carbon electrode surface, which was subsequently used for linkage of CRP recognition elements to form a biosensor with greater sensitivity (32.0 ± 0.5 μA/(ng/mL) than that formed by way of uncontrolled growth (26.6. ± 5.3 μA/(ng/mL) across a highly sensitive operating range of 0.01–10 ng/mL. To the best of our knowledge, this is the first report of this approach demonstrated as a route for biosensor fabrication. This finding suggests the approach can be exploited in immunosensor assays.

Electrochemical investigation of zinc tungstate nanoparticles; a robust sensor platform for the selective detection of furazolidone in biological samples

Alacritous determination, linear dynamic range, quick response time, and selectivity are the pivotal indices for developing electrochemical sensors. The researchers in the society are interested in upgrading the electroanalytical performance of electroactive materials with its chemical components and structures. Therefore, we have successfully prepared zinc tungstate nanoparticles (ZW NPs) via an ultrasonic-assisted co-precipitation synthesis technique. The as-prepared ZW NPs were cast on the screen-printed carbon electrode surface (SPCE) and utilized as a new electrode material for electrochemical detection of antibiotic drug furazolidone (FUZ). The structural morphology of as-prepared ZW NPs was analyzed with the assistance of FE-SEM, HR-TEM, and purity of nanomaterial formation were characterized by PXRD, Raman, and XPS. The electrochemical experiments were carried out using CV and DPV techniques. The ZW NPs/SPCE electrocatalyst shows an excellent sensing performance towards the determination of FUZ with a wide linear range from 0.1 to 849 μM, trace LOD, and sensitivity was assessed to be 13 nM and 0.77 µA µM−1 cm−2 respectively. This article marvels at the recent findings of nitrofuran drug detection in biological samples as a resilient and reliable FUZ sensor probe with good selectivity and excellent stability, and it attains cynical importance for surveying the ecosystem.

Hybrid nanomaterial/catalase-modified electrode for hydrogen peroxide sensing

Conjugation of biomolecules with hybrid nanomaterials offer opportunities in the assembly of (bio)sensors of improved electrochemical performance. This work reports on developing a novel catalase-functionalized hybrid nanomaterial for the detection of hydrogen peroxide (H 2 O 2 ). The rationally assembled (bio)sensor consists of iron nanoparticles coated with graphene's layers supported on multi-walled carbon nanotubes (Fe@G-MWCNTs), deposited at a screen-printed carbon electrode surface and functionalized with catalase. Transmission electron microscopy, X-ray diffraction-, X-ray photoelectron- and thermogravimetric-analysis were used to characterize the physicochemical properties of the hybrid nanomaterial and better understand its electrochemical behavior. The (bio)sensor response was linear from 0.1 to 7 mM, with a sensitivity of 0.059 μA/(μM.cm 2 ), a limit of detection of 28.2 μM, a Michaelis-Menten constant of 17.9 mM, and high reproducibility. The graphene flakes acted as a protective layer that prevented the loss of the Fe nanoparticles activity, thus improving the long-term stability of the (bio)sensor. • A hybrid nanomaterial (Fe@G-MWCNTs) of enhanced electro-analytical properties with respect to the individual components alone. • The hybrid as a suitable nanoenvironment for the catalase´s direct electrochemistry, maintaining its bioactivity and stability. • Cat/Fe@G-MWCNTs/SPCE biosensor with catalytic activity towards H 2 O 2 reduction, with high sensitivity and stability.

Impedimetric DNA E-biosensor for multiplexed sensing of Escherichia coli and its virulent f17 strains.

An impedance-based DNA multiplexed biosensor was designed to simultaneously detect Escherichia coli (yaiO gene) and its virulent f17 variant. The thiolated DNA dual probe was self-assembled onto the surface of the gold nanoparticle-modified screen-printed carbon electrode (AuNPs/SPCE) to recognize selected sequences from yaiO and f17 genes. The optimal conditions to prepare the bioelectrode were determined based on the monitoring of the impedimetric response fitted to an equivalent electrical circuit model. The charge transfer resistance of the bioelectrode increased by recognizing the target DNA sequences. Thelimit ofdetection was0.8fM and 1.0fM for yaiO and f17 target DNA, respectively, and the linearity ranged from 1 × 10-15 to 1 × 10-7M with a linear regression coefficient R ≥ 0.995. The nanodevice provided a novel strategy for simultaneous detection of E. coli and its virulence f17 gene with excellent discrimination with a single-base mismatch, two-base mismatch, and non-complementary sequences. Moreover, genomic DNA extracted from E. coli bacteria isolated from diarrheic camel calves and control animals in Tunisia was successfully detected using the as-prepared biosensor with minimal treatment of the extractedDNA samples.Graphical abstract.

Fabrication of a new electrochemical sensor based on screen-printed carbon electrode/amine-functionalized graphene oxide-Cu nanoparticles for Rohypnol direct determination in drink sample

Rohypnol or Flunitrazepam belongs to benzodiazepines (Schedule IV) with much higher and long-lasting effects on the central nervous system. Unfortunately, it is used in suicide and aggression. Since it can eventually be detected in the urine within 72 h, it is essential to measure it quickly and accurately. In this work, a new electrochemical sensor for the Rohypnol measurement was fabricated based on a modified screen-printed carbon electrode (SPCE). The SPCE surface was modified with amine-functionalized graphene oxide sheets reinforced through Cu nanoparticles)SPCE/AGO-Cu(with an average size of 30 nm. At the SPCE surface, an oxidation peak was observed for Rohypnol at a potential of 0.30 V. However, an oxidation peak at a potential of 0.25 V with two reduction peaks were appeared for Rohypnol at the SPCE surface modified with AGO-Cu in the potential range of 0 to 1 V. The ability of the SPCE/AGO-Cu to measure Rohypnol was studied. A linear dependency was resulted between Rohypnol concentration and SPCE/AGO-Cu response in the range of 0.4–140 μM and a limit of detection (LOD) of 0.13 μM in aqueous solution. According to the results, the SPCE/AGO-Cu provides an accurate and precise assay pathway of Rohypnol in the fruit juice.

Activated Graphite Supported Tunable Au-Pd Bimetallic Nanoparticle Composite Electrode for Methanol Oxidation.

Methanol (CH₃OH) is a favorable fuel for direct methanol fuel cells (DMFCs) in compact devices. This work, we present a facile and simple approach to make divergent molar ratios uniform gold (Au) and palladium (Pd) nanoparticles (NPs) decoration on an activated graphite (AGR) electrode. The binary combination of these AGR/Au-Pd catalysts composition is controlled by modifying the molar ratio of the Au and Pd precursors. The AGR/Au-Pd composite was characterized by suitable microscopy and spectroscopy characterization technique. Electrochemical studies of the prepared material were also conducted by chronoamperometry (CA) and cyclic voltammetry (CV) methods. The AGR/Au-Pd composite nanoparticles were successfully prepared and decorated on an activated screen-printed carbon electrode (ASPCE) surface. The ASPCE/AGR/Au-Pd electrode has great potential and stability for DMFCs. The prepared modified electrode was compared by a Pt/C electrode, and its efficiency was better than those of previously reported modified electrodes. Additionally, the electrocatalytic reaction of methanol oxidation is a surface controlled process on the electrode surface.

Highly branched gold-copper nanostructures for non-enzymatic specific detection of glucose and hydrogen peroxide.

The development of highly sensitive and highly selective sensors for non-enzymatic glucose and hydrogen peroxide (H2O2) detection using gold-copper alloy nanoparticles (AuCu alloy NPs) is reported. The AuCu NPs are nanostructures with branches and can be used as an electrochemical catalyst. Series of AuCu alloy NPs with various metal ratios are synthesized through acoreduction reaction. The morphology of AuCu alloy NPs is altered from highly branched structures (nanourchin, nanobramble, nanostar, nanocrystal) to a spherical shape by increasing Au content in the synthesis reaction. Cu-rich AuCu nanobramble and Au-rich AuCu nanostar exhibit selective electrocatalysis behaviors toward electro-oxidation of glucose and electroreduction of H2O2, respectively. The AuCu nanobramble-based sensor holds great potential in glucose detection with a linear working range of 0.25 to 10mM. The sensor possesses a sensitivity of 339.35μAmM-1cm-2, a limit of detection (LOD) of 16.62μM, which is an acceptable selectivity and good stability. In addition, the AuCu nanostar-based sensor shows excellent electrochemical responses toward H2O2 reduction with good selectivity, reproducibility, and a short response time of about 2-3s. The linear range for H2O2 determination is 0.05 to 10mM, with LOD and sensitivity of 10.93μM and 133.74μAmM-1cm-2, respectively. The good sensing performance is a result of the synergistic surface structure and atomic composition effects, which leads AuCu alloys to be a promising nanocatalyst for sensing both glucose and H2O2. Graphical abstract Schematic illustration presents the construction of gold-copper alloy nanoparticles (AuCu alloy NPs) on the surface of screen-printed carbon electrode (SPCE). The highly branched nanostructures of AuCu alloys with different surface structure and metal ratios give selective electrocatalysis behaviors. Cu-rich AuCu nanobramble-based sensor reveals prominent electrocatalytic activity for glucose detection. Au-rich AuCu nanostar-based sensor provides good electrochemical response for H2O2 detection.

Impedimetric immunosensor for rapid and simultaneous detection of chagas and visceral leishmaniasis for point of care diagnosis

In this work, a dual detection system based on an impedimetric immunosensor was developed for the first time for the simultaneous detection of anti-Trypanosoma cruzi and anti-Leishmania infantum antibodies in human and dog serum samples. The IBMP 8.1 and rLci1A/rLci2B recombinant antigens were immobilized over the surface of dual screen-printed carbon electrodes (W1 and W2) modified with poly (4-hydroxyphenylacetic acid). Under optimized conditions, the immunosensor recognized specific interactions for anti-T. cruzi antibodies up to a dilution of 1:10,240 and for anti-L. infantum up to 1:5120 in canine serum samples. Relative standard deviation (RSD) values of 2.8% for W1 and 3.6% for W2 were obtained for T. cruzi (W1) and L. infantum antigen (W2) samples in three different electrodes for 3 days (n = 9). The immunosensor was stored at 4 °C for 8 weeks, with activity retention of 70.2% in W1 and 78.2% in W2. The results using the recombinant proteins revealed that all antigens discriminated between negative and positive samples (p < 0.0001) in both dog and human groups, as well as no cross-reactivity could be detected among sera with other infections. With this approach, immunosensor-based diagnostic tests achieved 100% accuracy, suggesting that the antigens are eligible to enter Phase-II studies.

DNA Electrochemical Biosensor Based on Iron Oxide/Nanocellulose Crystalline Composite Modified Screen-Printed Carbon Electrode for Detection of Mycobacterium tuberculosis.

Death from tuberculosis has resulted in an increased need for early detection to prevent a tuberculosis (TB) epidemic, especially in closed and crowded populations. Herein, a sensitive electrochemical DNA biosensor based on functionalized iron oxide with mercaptopropionic acid (MPA-Fe3O4) nanoparticle and nanocellulose crystalline functionalized cetyl trimethyl ammonium bromide (NCC/CTAB) has been fabricated for the detection of Mycobacterium tuberculosis (MTB). In this study, a simple drop cast method was applied to deposit solution of MPA-Fe3O4/NCC/CTAB onto the surface of the screen-printed carbon electrode (SPCE). Then, a specific sequence of MTB DNA probe was immobilized onto a modified SPCE surface by using the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling mechanism. For better signal amplification and electrochemical response, ruthenium bipyridyl Ru(bpy)32+ was assigned as labels of hybridization followed by the characteristic test using differential pulse voltammetry (DPV). The results of this biosensor enable the detection of target DNA until a concentration as low as 7.96 × 10−13 M with a wide detection range from 1.0 × 10−6 to 1.0 × 10−12 M. In addition, the developed biosensor has shown a differentiation between positive and negative MTB samples in real sampel analysis.

Green preparation of reduced graphene oxide by Bougainvillea glabra flower extract and sensing application

In this paper, we report the application of Bougainvillea glabra flower extract as a green-reducing agent for the reduction of chemically prepared graphene oxide (GO). The removal of oxygen-containing functional groups after reduction of GO was due to the presence of phenolic compounds in the flower extract of Bougainvillea glabra. Towards the sensing of Pb2+, a simple drop-casting technique was adopted to fabricate the sensing element by modifying the surface of screen-printed carbon electrode (SPCE) with rGO-nafion nanocomposite. Differential pulse voltammetry was employed as an electroanalytical technique to study the sensing capability of the proposed electrode for different concentrations of Pb2+. The fabricated SPCE exhibited a low limit of detection of 0.05 nM toward Pb2+ with an improved sensitivity of 25.273 µA nM−1 over a linear range of 0.05–8.67 nM.

Carbon surfaces for the oxidative quantification of pravastatin: Glassy-carbon vs. screen-printed carbon electrodes

The electrooxidative behavior of pravastatin (PRV) in aqueous media was studied by square-wave voltammetry at a glassy-carbon electrode (GCE) and at a screen-printed carbon electrode (SPCE). Maximum peak current intensities in a pH 5.0 buffer were obtained at +1.3 V vs. AgCl/Ag and +1.0 V vs. Ag for the GCE and SPCE surface respectively. Validation of the developed methodologies revealed good performance characteristics and confirmed their applicability to the quantification of PRV in pharmaceutical products, without significant sample pretreatment. A comparative analysis between the two electrode types showed that SPCEs are preferred as an electrode surface because of their higher sensitivity and the elimination of the need to clean the electrode's surface for its renewal, which frequently is, if not always, the rate-limiting step in voltammetric analysis.

Rapid and label-free electrochemical DNA biosensor based on a facile one-step electrochemical synthesis of rGO-PPy-(L-Cys)-AuNPs nanocomposite for the HTLV-1 oligonucleotide detection.

Human T cell leukemia virus type 1 (HTLV-1) as the first human retrovirus is currently a serious endemic health challenge. Despite the use of assorted molecular or serological assays for HTLV-1 detection, there are several limitations due to the lack of a confirmatory test that may affect the accuracy of the results. Herein, a novel label-free biosensor for the detection of HTLV-1 Tax gene has been reported. An electrochemical facile ecofriendly synthesis method has been demonstrated based on a synthesis of nanocomposite of reduced graphene oxide, polypyrrole, and gold nanoparticles (rGO-PPy-(l-Cys)-AuNPs) deposited on the surface of screen-printed carbon electrode. Electrochemical techniques were used to characterize and study the electrochemical behavior of the rGO-PPy-(l-Cys)-AuNPs, which exhibited a stable reference peak at 0.21V associated with hybridization forms by applying the differential pulse voltammetry. The designed DNA biosensor presented a wide linear range from 0.1fM to 100µM and a low detection limit of 20 atto-molar. The proposed biosensor presented in this study provides outstanding selectivity, sensitivity, repeatability, and reproducibility.

An Immunosensor for the Detection of ULBP2 Biomarker.

Pancreatic cancer (PC) is a global health problem that features a very high mortality rate. The UL16 binding protein 2 (ULBP2) is a new biomarker for PC detection. This study develops a simple, reliable, and inexpensive immunosensor for the detection of the ULBP2 antigen while also investigating the effects of an array configuration of connected sensors and zinc oxide (ZnO) nanoparticles on the immunosensor’s sensitivity. The ULBP2 antibody was immobilized onto the screen-printed carbon electrode (SPCE) surfaces of three different sensors: a simple SPCE (ULBP2-SPCE); an SPCE array, which is a series of identical SPCE connected to each other at different arrangements of rows and columns (ULBP2-SPCE-1x2 and ULBP2-SPCE-1x3); and an SPCE combined with ZnO nanoparticles (ULBP2-ZnO/SPCE). Impedance spectrum measurements for the immunosensors to ULBP2 antigen were conducted and compared. According to the result, the array configurations (ULBP2-SPCE-1x2 and ULBP2-SPCE-1x3) show an improvement of sensitivity compared to the ULBP2-SPCE alone, but the improvement is not as significant as that of the ULBP2-ZnO/SPCE configuration (ULBP2-ZnO/SPCE > ULBP2-SPCE: 18 times larger). The ULBP2-ZnO/SPCE immunosensor has a low limit of detection (1 pg/mL) and a high sensitivity (332.2 Ω/Log(pg/mL)), excellent linearity (R2 = 0.98), good repeatability (coefficients of variation = 5.03%), and is stable in long-term storage (retaining 95% activity after 28 days storage). In an array configuration, the immunosensor has an increased signal-to-noise ratio (ULBP2-SPCE-1x3 > ULBP2-SPCE: 1.5-fold) and sensitivity (ULBP2-SPCE-1x3 > ULBP2-SPCE: 2.6-fold). In conclusion, either the modification with ZnO nanoparticles onto the sensor or the use of an array configuration of sensors can enhance the immunosensor’s sensitivity. In this study, the best immunosensor for detecting ULBP2 antigens is the ULBP2-ZnO/SPCE immunosensor.

Disposable immunoplatforms for the simultaneous determination of biomarkers for neurodegenerative disorders using poly(amidoamine) dendrimer/gold nanoparticle nanocomposite.

Early diagnosis in primary care settings can increase access to therapies and their efficiency as well as reduce health care costs. In this context, we report in this paper the development of a disposable immunoplatform for the rapid and simultaneous determination of two protein biomarkers recently reported to be involved in the pathological process of neurodegenerative disorders (NDD), tau protein (tau), and TAR DNA-binding protein 43 (TDP-43). The methodology involves implementation of a sandwich-type immunoassay on the surface of dual screen-printed carbon electrodes (dSPCEs) electrochemically grafted with p-aminobenzoic acid (p-ABA), which allows the covalent immobilization of a gold nanoparticle-poly(amidoamine) (PAMAM) dendrimer nanocomposite (3D-Au-PAMAM). This scaffold was employed for the immobilization of the capture antibodies (CAbs). Detector antibodies labeled with horseradish peroxidase (HRP) and amperometric detection at - 0.20V (vs. Ag pseudo-reference electrode) using the H2O2/hydroquinone (HQ) system were used. The developed methodology exhibits high sensitivity and selectivity for determining the target proteins, with detection limits of 2.3 and 12.8pgmL-1 for tau and TDP-43, respectively. The simultaneous determination of tau and TDP-43 was accomplished in raw plasma samples and brain tissue extracts from healthy individuals and NDD-diagnosed patients. The analysis can be performed in just 1h using a simple one-step assay protocol and small sample amounts (5μL plasma and 2.5μg brain tissue extracts). Graphical abstract.