An inverse-designed electrochemical platform for analytical applications

Label-free electrochemical immunosensor as a reliable point-of-care device for the detection of Interleukin-6 in serum samples from patients with psoriasis

Interleukin-6 (IL-6) plays a crucial role in autoimmunity and chronic inflammation. This study aims to develop a low-cost, simple-to-manufacture, and user-friendly label-free electrochemical point-of-care device for the rapid detection of IL-6 in patients with psoriasis. Precisely, a sandwich-based format immunosensor was developed using two primary antibodies (mAb-IL6 clone-5 and clone-7) and screen-printed electrodes modified with an inexpensive recycling electrochemical enhancing material, called biochar. mAb-IL6 clone-5 was used as a covalently immobilized capture bioreceptor on modified electrodes, and mAb-IL6 clone-7 was used to recognize the immunocomplex (Anti-IL6 clone-5 and IL-6) and form the sandwich. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to conduct electrochemical characterization of the layer-by-layer assembly of the immunosensor, while square wave voltammetry (SWV) was used to perform the sensing. The developed immunosensor demonstrated robust analytical performance in buffer solution, with a wide linear range (LR) by varying from 2 to 250 pg/mL, a good limit of detection (LOD) of 0.78 pg/mL and reproducibility (RSD<7%). In addition, a spectrophotometric ELISA kit was employed to validate the results obtained with the label-free device by analyzing twenty-five serum samples from control and patients affected by psoriasis. A strong correlation in terms of pg/mL concentration of IL-6 was found comparing the two methods, with the advantage for our label-free biosensor of an ease use and a quicker detection time. Based on IL-6 levels, the proposed immunosensor is a dependable, non-invasive screening device capable of predicting disease onset, progression, and treatment efficacy.

Preparation, Modification, and Application of Biochar in the Printing Field: A Review

Biochar is a solid material enriched with carbon produced by the thermal transformation of organic raw materials under anoxic or anaerobic conditions. It not only has various environmental benefits including reducing greenhouse gas emissions, improving soil fertility, and sequestering atmospheric carbon, but also has the advantages of abundant precursors, low cost, and wide potential applications, thus gaining widespread attention. In recent years, researchers have been exploring new biomass precursors, improving and developing new preparation methods, and searching for more high-value and meaningful applications. Biochar has been extensively researched and utilized in many fields, and recently, it has also shown good industrial application prospects and potential application value in the printing field. In such a context, this article summarizes the typical preparation and modification methods of biochar, and also reviews its application in the printing field, to provide a reference for future work.

A Deep Learning Approach to Organic Pollutants Classification Using Voltammetry

This paper proposes a deep leaning technique for accurate detection and reliable classification of organic pollutants in water. The pollutants are detected by means of cyclic voltammetry characterizations made by using low-cost disposable screen-printed electrodes. The paper demonstrates the possibility of strongly improving the detection of such platforms by modifying them with nanomaterials. The classification is addressed by using a deep learning approach with convolutional neural networks. To this end, the results of the voltammetry analysis are transformed into equivalent RGB images by means of Gramian angular field transformations. The proposed technique is applied to the detection and classification of hydroquinone and benzoquinone, which are particularly challenging since these two pollutants have a similar electroactivity and thus the voltammetry curves exhibit overlapping peaks. The modification of electrodes by carbon nanotubes improves the sensitivity of a factor of about ×25, whereas the convolution neural network after Gramian transformation correctly classifies 100% of the experiments.

Cost-effective and disposable label-free voltammetric immunosensor for sensitive detection of interleukin-6

IL-6 detection is highly desirable since can monitor many diseases in humans and assess the response to treatments. Herein, two novel label-free voltammetric immunosensors for rapid and accurate interleukin-6 (IL-6) detection in human serum are presented. The immunosensors are fabricated by immobilising two different IL-6 antibodies, identified as mAb-IL-6 clone-5 and clone-7, on in-house produced screen-printed electrodes modified with inexpensive recycling biochar (Bio-SPEs). To ensure high structural fidelity and performance, an in-depth electrochemical characterization of the layer-by-layer assembly of the immunosensor was conducted by cyclic voltammetry (CV) and sensing was performed using square wave voltammetry (SWV). The two immunosensors showed good analytical performances in human serum, exhibiting a wide linear range (LR) between 26-125 and 30-138 pg/mL, a good limit of detection (LOD) of 4.8 and 5.4 pg/mL and selectivity for IL-6 over other common cytokines, including IL-1β and TNF-α. Performance comparison of IL-6 immunosensors with those of a commercial spectrophotometric ELISA kit (LOD of 20 pg/mL, RSD% of 15%) denotes a better sensitivity and reproducibility of the proposed label-free devices, associated with a reduced detection time (30 min instead of more than 3 h for ELISA test). Furthermore, the proposed immunosensors were successfully applied in blood samples (with only a dilution of 1:100 v/v in PBS and without additional treatments) with good sensitivity (LOD of 14.3 pg/mL) and reproducibility (RSD% < 11%), thus paving the way for their application as viable diagnostic and therapeutic point-of-care tools alternative to the IL-6 detection techniques routinely used (ELISA and Western Blot).

Sensitive Detection of Industrial Pollutants Using Modified Electrochemical Platforms

Water pollution is nowadays a global problem and the effective detection of pollutants is of fundamental importance. Herein, a facile, efficient, robust, and rapid (response time < 2 min) method for the determination of important quinone-based industrial pollutants such as hydroquinone and benzoquinone is reported. The recognition method is based on the use of screen-printed electrodes as sensing platforms, enhanced with carbon-based nanomaterials. The enhancement is achieved by modifying the working electrode of such platforms through highly sensitive membranes made of Single- or Multi-Walled Carbon Nanotubes (SWNTs and MWNTs) or by graphene nanoplatelets. The modified sensing platforms are first carefully morphologically and electrochemically characterized, whereupon they are tested in the detection of different pollutants (i.e., hydroquinone and benzoquinone) in water solution, by using both cyclic and square-wave voltammetry. In particular, the sensors based on film-deposited nanomaterials show good sensitivity with a limit of detection in the nanomolar range (0.04 and 0.07 μM for SWNT- and MWNT-modified SPEs, respectively) and a linear working range of 10 to 1000 ppb under optimal conditions. The results highlight the improved performance of these novel sensing platforms and the large-scale applicability of this method for other analytes (i.e., toxins, pollutants).

Powerful Electron-Transfer Screen-Printed Platforms as Biosensing Tools: The Case of Uric Acid Biosensor

The use of carbon nanomaterials (CNMs) in sensors and biosensor realization is one of the hottest topics today in analytical chemistry. In this work, a comparative in-depth study, exploiting different nanomaterial (MWNT-CO₂H, -NH₂, -OH and GNP) modified screen-printed electrodes (SPEs), is reported. In particular, the sensitivity, the heterogeneous electron transfer constant (k⁰), and the peak-to-peak separation (ΔE) have been calculated and analyzed. After which, an electrochemical amperometric sensor capable of determining uric acid (UA), based on the nano-modified platforms previously characterized, is presented. The disposable UA biosensor, fabricated modifying working electrode (WE) with Prussian Blue (PB), carbon nanotubes, and uricase enzyme, showed remarkable analytical performances toward UA with high sensitivity (CO₂H 418 μA μM^-1 cm^-2 and bare SPE-based biosensor, 33 μA μM^-1 cm^-2), low detection limits (CO₂H 0.5 nM and bare SPE-based biosensors, 280 nM), and good repeatability (CO₂H and bare SPE-based biosensors, 5% and 10%, respectively). Moreover, the reproducibility (RSD%) of these platforms in tests conducted for UA determination in buffer and urine samples results are equal to 6% and 15%, respectively. These results demonstrate that the nanoengineered electrode exhibited good selectivity and sensitivity toward UA even in the presence of interfering species, thus paving the way for its application in other bio-fluids such as simple point-of-care (POC) devices.