Metal-Organic Frameworks Functionalized Porous Screen-Printed Electrodes for Label-Free Ratiometric Electrochemical Immunosensing of Mycotoxin.

A label-free impedimetric immunosensor for zearalenone based on CS-CNT-Pd nanocomposite modified screen-printed disposable electrodes

Flexible electrodes fabricated through cost-effective thick-film strategies are important for developing electrochemical devices, such as sensors. Properly engineered nanocomposite electrodes can enhance the electrochemically active surface area, facilitate mass and charge transport, and allow for tailored surface chemistry and structure. Although great efforts have been devoted to developing porous nanocomposite electrodes, a facile method to achieve screen-printed porous nanocomposite electrodes in the form of flexible electrodes with tunable electrochemical performance has been overlooked. This article introduces a strategy for fabricating flexible porous electrodes using screen printing and electrochemical surface treatments, resulting in enhanced surface chemistry and electrochemical properties. By applying selective etching and anodization, the electrode's surface area increases by 214% compared to a nontreated electrode, enabling programmable sensitivity to specific molecules. The engineered electrode improves the hydroquinone-to-salicylic acid detection ratio from less than 1 to over 10, allowing selective detection of neutral and positively charged molecules while rendering the electrode inactive for negatively charged species. This flexible sensor can be integrated into a wearable glove for rapid analysis and has also been successfully implemented in a second-generation glucose biosensor. This approach holds significant potential for advancing surface electrochemistry, offering new possibilities for tailoring electrode surfaces for diverse analytical applications.

Bismuth-based porous screen-printed carbon electrode with enhanced sensitivity for trace heavy metal detection by stripping voltammetry

A porous layer of copper was formed on the surface of screen-printed carbon electrodes via the colloidal crystal templating technique. An aqueous suspension of monodisperse polystyrene spheres of 500 nm particle diameter was drop-casted on the carbon tracks printed on the substrate made of alumina ceramic. After evaporation, the electrode was carefully dipped in copper plating solution for a certain time to achieve a sufficient penetration of solution within the polystyrene spheres. The metal was then electrodeposited galvanostatically over the self-assembled colloidal crystal. Finally, the polystyrene template was dissolved in toluene to expose the porous structure of copper deposit. The morphology of porous structures was investigated using scanning electron microscopy. Electroanalytical properties of porous copper film electrodes were evaluated in amperometric detection of selected saccharides, namely glucose, fructose, sucrose, and galactose. Using hydrodynamic amperometry in stirred alkaline solution, a current response at +0.6 V vs. Ag/AgCl was recorded after addition of the selected saccharide. These saccharides could be quantified in two linear ranges (0.2–1.0 μmol L−1 and 4.0–100 μmol L−1) with detection limits of 0.1 μmol L−1 glucose, 0.03 μmol L−1 fructose, and 0.05 μmol L−1 sucrose or galactose. In addition, analytical performance of porous copper electrodes was ascertained and compared to that of copper film screen-printed carbon electrodes, prepared ex-situ by the galvanostatic deposition of metal in the plating solution. After calculating the current densities with respect to the geometric area of working electrodes, the porous electrodes exhibited much higher sensitivity to changes in concentration of analytes, presumably due to the larger surface of the porous copper deposit. In the future, they could be incorporated in detectors of flow injection systems due to their long-term mechanical stability.

In order to identify carcinoembryonic antigen (CEA) in serum samples, an innovative smartphone-based, label-free electrochemical immunosensor was created without the need for additional labels or markers. This technology presents a viable method for on-site cancer diagnostics. The novel smartphone-integrated, label-free immunosensing platform was constructed by nanostructured materials that utilize the layer-by-layer (LBL) assembly technique, allowing for meticulous control over the interface. Detection relies on direct interactions without extra tagging agents, where ordered graphene oxide (GO), carbon nanotubes (CNTs), and copper oxide nanoparticles (CuONPs) were sequentially deposited onto a screen-printed carbon electrode (SPCE), designated as CuONPs/CNTs/GO/SPCE. This significantly amplifies the electrochemical signal, allowing for the detection of low concentrations of target molecules of CEA. The LBL approach enables the precise construction of multi-layered structures on the sensor surface, enhancing their activity and optimizing the electrochemical performance for CEA detection. These nanostructured materials serve as efficient carriers to significantly increase the surface area, conductivity, and structural support for antibody loading, thus improving the sensitivity of detection. The detection of carcinoembryonic antigen (CEA) in this electrochemical immunosensing transducer is based on a decrease in the current response of the [Fe(CN)6]3-/4- redox probes, which occurs in proportion to the amount of the immunocomplex formed on the sensor surface. Under the optimized conditions, the immunosensor exhibited good detection of CEA with a linear range of 0.1-5.0 ng mL-1 and a low detection limit of 0.08 ng mL-1. This label-free detection approach, based on signal suppression due to immunocomplex formation, is highly sensitive and efficient for measuring CEA levels in serum samples, with higher recovery ranges of 101% to 112%, enabling early cancer diagnosis. The immunosensor was successfully applied to determine CEA in serum samples. This immunosensor has several advantages, including simple fabrication, portability, rapid analysis, high selectivity and sensitivity, and good reproducibility with long-term stability over 21 days. Therefore, it has the potential for point-of-care diagnosis of lung cancer.

Direct electron transfer of Horseradish peroxidase on porous structure of screen-printed electrode

Label-free electrochemical impedance immunosensor based on modified screen-printed gold electrodes for the diagnosis of canine visceral leishmaniasis

Electrochemical processes are poised to play a pivotal role in the evolving global power system as the efficient interconversion of electrical and chemical energy can enable the deployment of sustainable technologies that support the decarbonization of the electric grid, power the automotive fleet, and offer new opportunities in chemical manufacturing. However, advances in electrochemical science and engineering are needed to address the stringent performance, cost, and scale requirements of these emerging application spaces. Many prominent electrochemical technologies (e.g., flow batteries, fuel cells, electrolyzers) leverage forced convection to increase volumetric productivity. Of particular importance to these systems are porous electrodes which provide surfaces for electrochemical reactions, manage reactant distribution, facilitate mechanical compression, and conduct electrons and heat. Accordingly, the systematic design and engineering of porous electrodes can greatly improve cell performance and durability.In this presentation, I will describe methods for disaggregating and quantifying resistive losses in porous electrodes using redox probes, diagnostic flow cells, and electrochemical modeling. I will then discuss how these tools can be used to guide the design of new electrode architectures with tailored property sets. Specifically, using redox flow batteries as an example, I will offer three vignettes. First, I will discuss the role of electrode microstructure and surface chemistry in balancing electrochemical and fluid dynamic performance within flow cells. Second, building on these results, I will describe efforts to develop electrodes using non-solvent induced phase separation, a synthetic approach which enables property combinations difficult to achieve via current manufacturing processes. Third and finally, I will highlight the potential of conductive particle suspensions as flowable, reconfigurable electrodes whose unusual electrochemical, rheological, and transport properties may unlock more versatile reactor designs.

3-Mercapto propionic acid self-assembled on gold nano-particles applied for modification of screen-printed electrode as a new digoxin electrochemical aptasensor using graphene oxide-based signal-on strategy

Porous boron doped diamond for dopamine sensing: Effect of boron doping level on morphology and electrochemical performance

Fabrication of high-performance non-enzymatic sensor by direct electrodeposition of nanomaterials on porous screen-printed electrodes

Thedesign and fabrication of a surface-enhanced Raman scattering (SERS) aptasensor forsimultaneous detection of zearalenone (ZEN) and ochratoxin A (OTA) in wheat and corn samplesis described. The capture and reporter probes were SH-cDNA-modified gold nanorods and SH-Apt-modified Au@Ag core-shell nanoparticles, respectively. After recognizing OTA and ZEN aptamers and complementary strands (SH-cDNA), the reporter probe generated a strong SERS signal. The preferred binding of OTA and ZEN aptamers to OTA and ZEN, respectively, caused reporter probes to release the capture probes, resulting in a linear decrease in SERS intensity. The detection of OTA showed good linearity with an R2 value of 0.986, which could be maintained across a wide concentration range (0.01 to 100 ng/mL), with the limit of detection of 0.018 ng/mL. Fordetection of ZEN, good linearity with an R2 value of 0.987 could be maintained across a wide concentration range (0.05 to 500 ng/mL), with 0.054 ng/mL as the limit of detection. Goodaccuracy (relative standard deviation < 4.2%) during mycotoxin determination as well as excellent quantitative recoveries (96.0-110.7%) during the analysis of spiked real samples was achieved. The proposed SERS aptasensor exhibited excellent performance in the detection of OTA and ZEN in real food samples. Hence, by simply changing the aptamer, this new model can be applied tothe detection of multiple mycotoxins in the food industry.

A novel PPtNPs/rGO@Cu(BDC-NH2) MOF/PEDOT@PB/SPCE platform for ultra-sensitive label-free electrochemical immunosensor for prostate-specific antigen.

Sequential injection-differential pulse voltammetric immunosensor for hepatitis B surface antigen using the modified screen-printed carbon electrode

A toluidine blue/porous organic polymer/2D MoSe2 nanocomposite as an electrochemical signaling platform for a sensitive label-free aflatoxin B1 bioassay in some crops