Fabrication Of Screen-printed Electrodes Research Articles

Disposable graphene-oxide screen-printed electrode integrated with portable device for detection of SARS-CoV-2 in clinical samples

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnosis is the need of the hour, as cases are persistently increasing, and new variants are constantly emerging. The ever-changing nature of the virus leading to multiple variants, has brought an imminent need for early, accurate and rapid detection methods. Herein, we have reported the design and fabrication of Screen-Printed Electrodes (SPEs) with graphene oxide (GO) as working electrode and modified with specific antibodies for SARS-CoV-2 Receptor Binding Domain (RBD). Flexibility of design, and portable nature has made SPEs the superior choice for electrochemical analysis. The developed immunosensor can detect RBD as low as 0.83 fM with long-term storage capacity. The fabricated SPEs immunosensor was tested using a miniaturized portable device and potentiostat on 100 patient nasopharyngeal samples and corroborated with RT-PCR data, displayed 94 % sensitivity. Additionally, the in-house developed polyclonal antibodies detected RBD antigen of the mutated Omicron variant of SARS-CoV-2 successfully. We have not observed any cross-reactivity/binding of the fabricated immunosensor with MERS (cross-reactive antigen) and Influenza A H1N1 (antigen sharing common symptoms). Hence, the developed SPEs sensor may be applied for bedside point-of-care diagnosis of SARS-CoV-2 using miniaturized portable device, in clinical samples.

Fabrication of screen-printed electrodes: opportunities and challenges

In recent times, wearable electronics, real-time sensing devices and point-of-care device applications have seen a surge in demand. This demand inherently calls for a more economic and reliable method of mass production. One such robust technique is screen printing that offers advantages in terms of being versatile, economical and easy to use. This technique has been proclaimed to be the best amongst the other additive manufacturing techniques by many research groups. This can be solely attributed to its simple equipment design, requiring a paste for printing purpose, a meshwork for housing the design and a squeegee to carry out printing through an up-and-down motion. This subsequently calls for optimising the parameters such as ink rheology, pore size of the mesh, proper choice of mesh design and motion of the squeeze in order to fabricate electrodes for desired purpose. Due to this technique’s immense potential to open up broad inroads in the domain of flexible electronics, whose concept has radically redefined the perception towards the field of electronics, a review article encompassing an elaborate description on the science and other quintessential parameters involved in this mass printing technique would prove to be extremely useful. In this purview, the review article is compartmentalised into sections encompassing discussion on the manufacturing of different kinds of inks for screen printing applications, substrates used, electrode design and pre-treatment procedures.

A Study of Optimization of Various Parameters in the Fabrication of Screen-Printed Electrodes

Screen-printed electrode (SPE) is now a very well-established approach for the development of electrochemical sensors owing to their disposability, sensitivity, low sample volume requirement, rapid analysis time, and low-cost batch production. The main challenge associated with the fabrication of SPEs is their reproducibility. Various parameters are involved in the fabrication of SPEs. It is very important to optimize the fabrication parameters in such a way so as to ensure both interbatch as well as intrabatch reproducibility. Analyzing the cause behind the best electrochemical performance at optimized parameters is another very important area of research as it leads to the understanding and development of superior electrode materials. This paper discusses certain vital fabrication parameters, their optimization and characterizations, so as to obtain an insight into the underlying causes that might affect the electrochemical performance of SPEs.

Magnetron Sputter-Coated Nanoparticle MoS2 Supported on Nanocarbon: A Highly Efficient Electrocatalyst toward the Hydrogen Evolution Reaction.

The design and fabrication of inexpensive highly efficient electrocatalysts for the production of hydrogen via the hydrogen evolution reaction (HER) underpin a plethora of emerging clean energy technologies. Herein, we report the fabrication of highly efficient electrocatalysts for the HER based on magnetron-sputtered MoS2 onto a nanocarbon support, termed MoS2/C. Magnetron sputtering time is explored as a function of its physiochemical composition and HER performance; increased sputtering times give rise to materials with differing compositions, i.e., Mo4+ to Mo6+ and associated S anions (sulfide, elemental, and sulfate), and improved HER outputs. An optimized sputtering time of 45 min was used to fabricate the MoS2/C material. This gave rise to an optimal HER performance with regard to its HER onset potential, achievable current, and Tafel value, which were −0.44 (vs saturated calomel electrode (SCE)), −1.45 mV s–1, and 43 mV dec–1, respectively, which has the highest composition of Mo4+ and sulfide (MoS2). Electrochemical testing toward the HER via drop casting MoS2/C upon screen-printed electrodes (SPEs) to electrically wire the nanomaterial is found to be mass coverage dependent, where the current density increases up to a critical mass (ca. 50 μg cm–2), after which a plateau is observed. To allow for a translation of the bespoke fabricated MoS2/C from laboratory to new industrial applications, MoS2/C was incorporated into the bulk ink utilized in the fabrication of SPEs (denoted as MoS2/C-SPE), thus allowing for improved electrical wiring to the MoS2/C and resulting in the production of scalable and reproducible electrocatalytic platforms. The MoS2/C-SPEs displayed far greater HER catalysis with a 450 mV reduction in the HER onset potential and a 1.70 mA cm–2 increase in the achievable current density (recorded at −0.75 V (vs SCE)), compared to a bare/unmodified graphitic SPE. The approach of using magnetron sputtering to modify carbon with MoS2 facilitates the production of mass-producible, stable, and effective electrode materials for possible use in electrolyzers, which are cost competitive to Pt and mitigate the need to use time-consuming and low-yield exfoliation techniques typically used to fabricate pristine MoS2.

Affinity Methods to Immobilize Acetylcholinesterases for Manufacturing Biosensors

Two new affinity methods to immobilize acetylcholinesterase (AChE) onto screen‐printed electrodes (SPE) are described and compared for the fabrication of SPE: one based on metal chelate affinity (MCA) and one based on the Concanavalin A (Con A), a sugar residue binding lectine. The manufacturing and the optimization procedure for each type of biosensor are discussed with respect to no‐specific binding, functionalization of the SPE surface and the amount of enzyme used. A linear response range to acetylthiocholine substrate between 10 and 100 µmol L−1 was obtained for Con A sensors and between 1 and 60 µmol L−1 with the MCA sensors. The possibilities to reuse the sensors fabricated using both affinity immobilization chemistries were also discussed. The optimized sensors were used to study the inhibitory effects of organophosphorus pesticides on immobilized AChE activity. A detection limit of 5 × 10−7 mol L−1 chlorpyrifos methyl‐oxon (ee AChE sensor) and 2 × 10−9 mol L−1 paraoxon (dm AChE sensor) was achieved for the sensors with the enzyme attached via Con A and NTA–Ni, respectively.

Development of Highly Sensitive Sensor Based on Bioengineered Acetylcholinesterase Immobilized by Affinity Method†

A new method for the immobilization of a bioengineered His-tagged acetylcholinesterase onto a chemically modified graphite is described for the fabrication of screen-printed electrodes. The choice of the enzyme, the functionalization of the graphite and the analytical characteristics of the electrodes were studied. The nonspecific binding and the effect of the pH were also evaluated. A sensitivity of 4 mA L mol−1 was obtained between 1–60 μmol L−1 acetylthiocholine, one order of magnitude higher than in the case of entrapment in PVA-SbQ or Sol-Gel. The acetylcholinesterase sensors remained fully stable after 80 days storage at 4°C under vacuum, with a response of 327 nA, with 1 mM substrate. In the absence of vacuum the electrodes lose more than 30% of the initial value after 15 days and they have completely lost their activity after 30 days. The sensors can be reused by elution of inhibited enzyme either with a solution of imidazole or with ethylenediaminetetraacetic acid (EDTANa2H2). The developed system was applied for the detection of an acetylcholinesterase inhibitor, paraoxon, a detection limit of 2 nmol L−1 being obtained following a 10 min incubation. † This article is dedicated to Professor Pierre Coulet, University Lyon 1.

Electrochemical study of chemically modified and screen-printed graphite electrodes with

The preparation and electrochemical characterization of graphite electrodes modified with hexadecylpyridinium-bis(chlorilato)-antimonyl(V), [SbVO(CHL)2]Hex, (CMEs) as well as their behavior as electrocatalysts toward the oxidation of sulfide are described. The self-exchange rate constant ko of immobilized [SbVO(CHL)2]Hex and the effect of the surface coverage were evaluated. [SbVO(CHL)2]Hex is a new compound. Synthesis protocol and some identification studies are given. The fabrication of screen-printed electrodes (SPEs) with a mixture of 5% (w/ w) [SbVO(CHL)2]Hex/graphite powder in 1.5% (w/v) ethyl cellulose in 2-butoxyethyl acetate is also described. SPEs, poised at +0.08 mV versus Ag/AgCl, at pH 6.5 were utilized for the determination of sulfide in simulated wastewater samples. Interference of various compounds was also tested. The proposed method correlates well with a colorimetric method. Calibration graphs were linear over the range 0.01-0.7 mM sodium sulfide and the CV was 2.8% (n = 8) for 0.1 mM sodium sulfide. Recovery ranged from 94 to 102%. Both [SbVO(CHL)2]Hex CMEs and SPE showed very good storage stability. [SbVO(CHL)2]Hex CMEs showed poor working stability in contrast to printed electrodes, which operated with no remarkable loss of their initial activity for more than 100 runs.

Screen-printable surfactant-induced sol–gel graphite composites for electrochemical sensors

Abstract A novel procedure to prepare sol–gel graphite composite electrodes is presented. This procedure uses the surfactant bis(2-ethylhexyl) sulfosuccinate (AOT) and eliminates the need for a cosolvent, an acidic catalyst, a cellulose binder and thermal curing. Cobalt phthalocyanine (CoPC), diphenylthiocarbazone (DPT) and glucose oxidase (GOx)/ferrocene (Fc) were encapsulated during the surface preparation to study the utility of these composites as catalytic surfaces and biochemical sensors. The glucose sensor has a useful working range up to 30 mM with a 10 s response time. The DPT-modified electrode has been applied for lead determination based on a complexing/voltammetric strategy. The CoPC modified surface was catalytically active for reduced glutathione (GSH) reducing the onset potential for its oxidation by 400 mV. Fabrication of screen-printed electrodes by this method proved to be a simple approach for electroanalytical applications in aqueous and nonaqueous solvents.