Disposble electrochemical aptasensors: From design strategies, signal amplification, to applications and future perspectives.

T-2 mycotoxin: From occurrence and toxicokinetics to recent advances in aptasensor-based detection strategies and future perspectives for enhanced food safety

Carcinoembryonic antigen (CEA) is a critical biomarker for diagnosing and monitoring cancers such as liver, colon, and breast cancer. This study presents a highly sensitive surface plasmon resonance (SPR) sensor incorporating 2D materials—graphene and MXene (Ti3C2TX)— in a Kretschmann configuration. The sensor, comprising a BK7 prism, gold (Au), graphene, aluminum oxide (Al₂O₃), and MXene, is optimized for detecting CEA in aqueous solutions with high precision. The performance of the proposed sensor was evaluated using the finite difference time domain (FDTD) numerical method, focusing on key parameters such as sensitivity and figure of merit (FOM). Operating at a wavelength of 633 nm, the sensor achieved an exceptional sensitivity of 163.63 deg/RIU and an FOM of 17.52 RIU⁻¹, marking a significant improvement over previously reported SPR biosensors. Comparative analysis further underscores the superior performance of this design, establishing it as a cutting-edge tool for applications in biosensing, medical diagnostics, food safety, and environmental monitoring. The proposed sensor offers significant potential for real-world applications, including clinical diagnostics for early cancer detection, food safety monitoring, and environmental sensing.

A sensitive electrochemical aptasensor for multiplex antibiotics detection based on high-capacity magnetic hollow porous nanotracers coupling exonuclease-assisted cascade target recycling

Disposable electrochemical aptasensor with mesoporous carbon spheres modified screen-printed dual-working electrodes for Pb2+ and Hg2+ detection

Immobilization-free electrochemical homogeneous aptasensor for highly sensitive detection of carcinoembryonic antigen by dual amplification strategy

With the development of technologies in printed electronics, they are perfect for low performance applications, such as displays, labels, clothing, and batteries. Flexible, electrical circuits can be printed using functional inks and printing methods, such as screen printing, gravure and inkjet. Uniform ink surface, smoothness, fine lines, and registration are keys in determining the capability of printed electronics. Screen mesh count, printing methods and emulsion thickness are all variables that are involved in screen printing and need to be quantified in order to determine optimal operational conditions. Inkjet printing is used to conductive traces based on its tiny drop. This study attempted to control human errors during operation that might influence electrical conductivity with inkjet and screen printing.

In the present study, an electronic tongue (e-tongue) system based on cyclic voltammetry (CV) with three electrodes (pencil graphite (PG), screen printed (SP), and glassy carbon (GC)) was fabricated to investigate and detect heavy metals, such as cadmium (Cd), lead (Pb), tin (Sn), and nickel (Ni) (at three concentrations of 0.05, 0.1, and 0.25 ppm) in sunflower edible oil. The results from cyclic voltammograms showed that GC, PG, and SP electrodes have the highest cathodic current peaks and show higher sensitivity to the presence of heavy metals in sunflower edible oil, respectively. Moreover, the principal component analysis method was used to classify heavy metals. The obtained results showed that the three intended electrodes were capable of well detecting data. Overall, PG, SP, and GC electrodes account for 84%, 98%, and 88% of the variance between data, respectively. Additionally, a support vector machine (SVM) and K-nearest neighbor (K-NN) were used for classification. High accuracies were obtained for the PG, SP, and GC electrodes. Besides, The K-NN method combined with the intended electrodes could well perform classification, and GC was the best electrode. In the following, the partial least square method could predict data for PG, SP, and GC electrodes with an accuracy of 98%, 99%, and 81%, respectively. Finally, it can be said that the fabricated e-tongue combined with chemometric methods could classify heavy metals, in edible oil with high accuracy. Practical applications In this research, an e-tongue system was developed based on three electrodes (PG, SP, and GC) to identify heavy metals in sunflower edible oil using chemometric methods. According to results, e-tongue combined with chemometric method has high ability for food quality monitoring.

Even though a plethora of printing technologies are currently available and their potential for the fabrication of low-cost and flexible sensors has been widely investigated, systematically based, and statistically sustained comparative studies are missing in the literature. In this work, we compare screen, inkjet, and dispense printing for the fabrication of carbon nanotube (CNT)-based ammonia (NH3) chemiresistive flexible gas sensors for the first time. Moreover, we report the first CNT-based gas sensor fabricated via Voltera printer. The devices were made of a thin layer of spray-coated CNTs and printed silver-based interdigitated electrodes. To draw a thoughtful comparison the same sensor layout, materials, and fabrication flow were used. The device morphological features were acquired through microscopic, atomic force microscope, and 3D images; additionally, the response to NH3 as well as the printing process characteristics for each technique was analyzed. From 300 µm nominal spacing between lines, we obtained a decrease of 25%, 13%, and 5% on the printed spacings with dispense, screen, and inkjet printing, respectively. At 100 ppm of NH3, a maximum response of 33%, 31%, and 27% with the dispense-, inkjet-, and screen-printed sensors were found, respectively. Statistical differences were observed between the mean values on the NH3 response of dispense- compared to the inkjet- and screen-printed sensors, which in effect showed the highest response in the Tukey test. This demonstrated that the fabrication technique employed can induce a different response mainly driven by the printed outcomes. Following a holistic approach that includes the sensor response, the application, the market perspective, and the process versatility, we suggest screen printing as the most suitable method for CNT-based NH3 gas sensor fabrication.

Enzyme-free electrochemical aptasensor by using silver nanoparticles aggregates coupling with carbon nanotube inducing signal amplification through electrodeposition

Carbon monoxide (CO) sensors are critical for safety applications in residential settings, industrial workplaces, environmental monitoring, and healthcare diagnostics. Additionally, CO serves as a biomarker for respiratory and inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Therefore, the development of a highly sensitive CO sensor capable of detecting trace concentrations is of significant importance. In this study, we present, for the first time, a highly selective and stable chemiresistive CO sensor based on yttrium iron garnet (Y₃Fe₅O₁₂). The material was synthesized via a sol-gel method under varying pH conditions and characterized using XRD, FESEM, EDX, XPS, BET, and UV-vis spectroscopy. XRD analysis confirmed that a pure garnet phase formed under highly acidic conditions, whereas a mixed phase appeared at neutral or less acidic pH. Gas sensing studies demonstrated that the phase-pure Y₃Fe₅O₁₂ sensor exhibited an ultrafast response (3s) and recovery (4s) with a ∼37-fold p-type sensing response toward 100ppm CO. It maintained high sensitivity even at 500 ppb CO (∼5-fold response) and showed exceptional selectivity against common interfering gases. The sensor remained stable for over 120 days, highlighting its potential for real-world applications in environmental monitoring and medical diagnostics.

Amplified oxygen reduction signal at a Pt-Sn-modified TiO2 nanocomposite on an electrochemical aptasensor

Ultra-sensitive, on-site pesticide detection for environmental and food safety monitoring using flexible cellulose nano fiber/Au nanorod@Ag SERS sensor.

Simple and sensitive aptasensor based on quantum dot-coated silica nanospheres and the gold screen-printed electrode

A sandwich electrochemical sensor was fabricated based on multi-walled carbon nanotubes/ordered mesoporous carbon/AuNP (MWCNTs/CMK-3/AuNP) nanocomposites and porous core-shell nanoparticles Au@PdNPs to achieve rapid and sensitive detection of AFB1 in complex matrices. MWCNTs/CMK-3/AuNP nanocomposite, which was prepared by self-assembly method, served as a substrate material to increase the aptamer loading and improve the conductivity and electrocatalytic activity of the electrode for the first signal amplification. Then, Au@PdNPs, which were synthesized by one-pot aqueous phase method, were applied as nanocarriers loaded with plenty of capture probe antibody (Ab) and signal molecule toluidine blue (Tb) to form the Au@PdNPs-Ab-Tb bioconjugates for secondary signal amplification. The sensing system could still significantly improve the signal output intensity even in the presence of ultra-low concentration target compounddue to the dual signal amplification of MWCNTs/CMK-3/AuNP nanocomposites and Au@PdNPs-Ab-Tb. The method exhibited high selectivity, low detection limit (9.13fg/mL), and strong stability to differentiate AFB1 from other mycotoxins. Furthermore, the sensor has been successfully applied to the quantitative determination of AFB1 in corn, malt, and six herbs, which has potential applications in food safety, quality control, and environmental monitoring.

Prussian Blue (PB) is commonly incorporated into screen-printed enzymatic devices since it enables the determination of the enzymatically produced hydrogen peroxide at low potentials. Inkjet printing is gaining popularity in the development of electrochemical sensors as a substitute for screen printing. This work presents a fully inkjet-printed graphene-Prussian Blue platform, which can be paired with oxidase enzymes to prepare a biosensor of choice. The graphene electrode was inkjet-printed on a flexible polyimide substrate and then thermally and photonically treated with intense pulsed light, followed by inkjet printing of a PB nanoparticle suspension. The optimization of post-printing treatment and electrode deposition conditions was performed to yield a platform with minimal sheet resistance and peak potential differences. A thorough study of PB deposition was conducted: the fully inkjet-printed system was compared against sensors with PB deposited chemically or by drop casting the PB suspension on different kinds of carbon electrodes (glassy carbon, commercial screen-printed, and in-house inkjet-printed electrodes). For hydrogen peroxide detection, the fully inkjet-printed platform exhibits excellent sensitivity, a wider linear range, better linearity, and greater stability towards higher concentrations of peroxide than the other tested electrodes. Finally, lactate oxidase was immobilized in a chitosan matrix, and the prepared biosensor exhibited analytical performance comparable to other lactate sensors found in the literature in a wide, physiologically relevant linear range for measuring lactate concentration in sweat. The development of mediator-modified electrodes with a single fabrication technology, as demonstrated here, paves the way for the scalable production of low-cost, wearable, and flexible biosensors.