Pavol Gemeiner

Composition of conductive inks plays a decisive role in determining both printability and electrochemical performance of screen-printed electrochemical sensors. In this work, composite conductive inks based on graphitic carbon nitride (g-C ₃ N ₄ ) and activated carbon (AC) were prepared with systematically varied filler ratios and evaluated by rheological measurements, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. All inks exhibited shear-thinning behavior suitable for screen printing, while increasing the g-C ₃ N ₄ content enhanced the low-shear viscosity and promoted rapid structural recovery after shear. Scanning electron microscopy revealed that nanosized g-C ₃ N ₄ filled the interparticle voids between larger AC particles, producing a denser and more homogeneous composite microstructure. Electrochemical performance was evaluated using a [Fe(CN) ₆ ] ^3−/4− redox probe. Increasing the AC fraction reduced the peak-to-peak separation from 130 mV for pure g-C ₃ N ₄ electrode to 100 mV for the 50:50 and 25:75 composites, indicating more facile interfacial charge-transfer kinetics, although the associated Faradaic peak currents decreased with the increasing AC content due to lower density of g-C ₃ N ₄ -associated redox-active sites. Electrochemical impedance spectroscopy showed a substantial decrease in charge-transfer resistance from 148.5 Ω cm ² for pure g-C ₃ N ₄ to 7.2 Ω・cm ² for g-C ₃ N ₄ :AC (25:75) composite, outperforming even pure AC electrode (16.9 Ω・cm ² ). The results demonstrate synergistic interaction between both conductive components. Both materials, g-C ₃ N ₄ and AC, provide electrochemically active surface sites that promote the Faradaic response, whereas AC establishes an efficient conductive network that facilitates charge transport. The optimized g-C ₃ N ₄ :AC (25:75) represents a promising conductive ink for the fabrication of low-cost, reliable, screen-printed electrodes that can be readily modified through further surface or bulk functionalization for diverse electrochemical sensing applications.

[This corrects the article DOI: 10.1021/acsomega.5c05879.].

This study presents a rapid, environmentally friendly, and scalable activation method for 3D-printed poly­(lactic acid)/carbon black (PLA/CB) electrodes using atmospheric air plasma under ambient conditions. The goal was to optimize the plasma activation time and compare its efficiency with conventional activation techniques using N,N-dimethylformamide (DMF) and sodium hydroxide (NaOH). Surface morphology, chemical composition, wettability, and electrochemical performance were systematically evaluated through scanning electron microscopy (SEM), Raman spectroscopy, XPS, contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Plasma treatment, as short as 5 s, effectively removed the PLA matrix from the electrode surface, enhanced surface roughness, hydrophilicity, and exposure of conductive carbon black particles, leading to increased electrochemical performance. Compared to chemical activation, 40 s of plasma activation yielded comparable performance with significantly shorter processing times (vs NaOH) and without hazardous solvents (such as DMF). Finally, the activated electrodes were successfully applied in the development, optimization, and validation of a novel electrochemical protocol for the determination of the antihypertensive drug amlodipine, revealing high sensitivity, a low limit of detection of 0.09 μM, precision (RSD of 6.6%), and recovery (97.1 and 105.4%) in pharmaceutical formulations. The findings demonstrate the promising potential of air plasma activation as a sustainable and efficient approach for preparing 3D-printed electrodes for analytical and sensing applications.

Silver nanoparticles (AgNPs) have attracted tremendous attention in recent years due to their unique physicochemical properties, including pronounced surface plasmon resonance, tunable size, and amenability to functionalization. These attributes underpin the growing interest in AgNPs as SMART nanocarriers for targeted drug delivery and as active components in biosensing platforms. In this work, we discuss various synthesis strategies for AgNPs—ranging from conventional chemical methods to green approaches—and highlight their subsequent functionalization with anticancer drugs, notably doxorubicin (DOX). We also examine the potential of AgNPs in biosensor applications, emphasizing electrochemical and optical detection modalities capable of monitoring drug release, oxidative stress, and relevant biomarkers. Our experimental data support the conclusion that AgNPs can effectively improve therapeutic efficacy by exploiting tumor-specific conditions (e.g., lower pH) while also enhancing biosensor sensitivity via surface plasmon resonance and electrochemical signal amplification. We provide a thorough discussion of the results, including mechanistic aspects of reactive oxygen species (ROS) generation, drug release kinetics, and sensor performance metrics. Overall, AgNP-based nanocarriers emerge as a powerful platform to address current challenges in precision oncology and medical diagnostics.

Pad printing is not a widely used printing technique, but it offers the possibility of a simple, fast, and low‐cost production of various high‐resolution electrode structures. Here, the pad‐printed reduced graphene oxide (rGO) electrodes are prepared from pad‐printable inks containing rGO powder and different concentrations of two cellulose‐based polymers: ethylcellulose and cellulose acetate butyrate. The applicability of rGO inks for pad printing is analyzed according to their rheological parameters and printability. Based on viscosity, storage (G′) and loss modulus (G″) values, 10 wt% of ethylcellulose and 15 wt% of cellulose acetate butyrate appear to be most suitable for pad printing. The effect of polymer concentration on rGO electrodes homogeneity and mechanical stability is also evaluated. Cyclic voltammetry measurements for [Fe(CN)₆]^3−/4− redox system are performed with rGO/cellulose inks pad‐printed onto transparent conductive oxide substrates with the best results when using ethylcellulose as a binder. Finally, the square‐wave voltammetric method assesses the viability of rGO electrodes for the fast detection of ascorbic acid (detection limit of 15 μM) coupled with satisfactory precision (4.5%, n = 5) and long‐term stability during electrochemical measurements.

Biochar, a biologically originated carbon-rich material derived from the oxygen-limited pyrolysis of biomass, is usually added to the soil for its enrichment, increasing its water-holding capacity and pH. This revolutionary material thus contributes to a reduction in the overall environmental impact and mitigation of climate change. Due to the beneficial properties of this material, especially for electrochemical applications (large active surface area, conductivity, etc.), biochar demonstrates an extremely high capacity for the adsorption and detection of micropollutants simultaneously. However, finding the optimal conditions for the adsorptive and electrochemical properties of prepared biochar-based sensors is crucial. The adsorption efficiency should be sufficient to remove pollutants, even from complex matrices; on the other hand, the electrochemical properties, such as conductivity and charge transfer resistance, are key factors concerning the sensing ability. Therefore, the balanced design of biochar can ensure both the usability and the effectiveness of sensing. To enhance levels of electroactivity that are already high, the pre- or post-modification of biochar can be performed. Such recycled carbon-based materials could be promising candidates among other electrochemical sensing platforms. In this study, different biochar modifications are presented. Utilizing important biochar properties, it should be possible to create a bifunctional platform for removing micropollutants from water systems and simultaneously confirming purification levels via their detection. We reviewed the use of biochar-based materials for the effective removal of micropollutants and the methods for their detection in water matrices.