Martin Jönsson-Niedziółka

Ion transfer voltammetry using arrays of micro-interfaces between two immiscible electrolyte solutions (μITIES) has emerged as a promising tool for analysis of environmental samples. Here we show that using a gelled organic phase, we can combine μITIES electrochemistry with ex situ techniques, such as confocal fluorescence microscopy. By investigating the transfer of the ionized fluorophore fluorescein, we can use fluorescence confocal microscopy to evaluate the distribution of ions in the organic phase after transfer. We show that the concentration of the fluorophore close to the ITIES after transfer using a constant applied potential is substantially higher than in the aqueous phase, even after a short transfer period. This demonstrates that the use of a high-viscosity organic phase is very promising for analysis and also allows for the combination of ITIES electrochemistry with an array of ex situ measurement techniques.

Electrochemical studies of the interface between two immiscible liquids (ITIES) are gaining increasing importance due to the biomimetic nature of ion transfer processes and their broad potential for analytical applications. Despite their numerous advantages, classical ITIES systems exhibit significant limitations, primarily due to the low mechanical stability of the phase boundary and the use of toxic, poorly conducting organic solvents. In response to these challenges, we have developed a compact ITIES system based on a paper, in which the paper serves as a carrier for both liquid phases. The porous structure of cellulose stabilizes the solutions and enables controlled liquid transport. Furthermore, the incorporation of an organogel results in a more stable and miniaturizable phase boundary with well-defined geometry, leading to high repeatability in electrochemical measurements. This platform presents a promising solution for low-cost, single-use analytical systems based on ITIES electrochemistry, making it suitable for point-of-need applications and compatible with portable potentiostats.

Ion transfer voltammetry using arrays of micro-interfaces between two immiscible electrolyte solutions (µITIES) has emerged as a promising tool for analysis of environmental samples. Here we show that using a gelled organic phase, we can combine µITIES electrochemistry with ex situ techniques, such as confocal fluorescence microscopy. By investigating the transfer of the ionized fluorophore fluorescein, we can use fluorescence confocal microscopy to evaluate the distribution of ions in the organic phase after transfer. We show that the concentration of the fluorophore close to the ITIES after transfer using a constant applied potential is substantially higher than in the aqueous phase, even after a short transfer period. This demonstrates that the use of a high-viscosity organic phase is very promising for analysis and also allows for the combination of ITIES electrochemistry with an array of ex situ measurement techniques.

Co ²⁺ -doping increases the electrocatalytic performance of MnO ₂ films for the determination of H ₂ O ₂ .

Electroconductive hydrogels offer a unique combination of conductivity and biocompatibility, mimicking the extracellular matrix for bioelectronic applications. Herein, we present a homogeneous, conductive, and cytocompatible hydrogel-based organic electrochemical transistor (OECT) composite, combining methacrylated gelatin (GelMA), PEDOT:PSS, and tetramethacrylated PEDOT:TOS (PEDOT-TMA:TOS). This three-component hydrogel overcomes challenges in PEDOT aggregation, low conductivity, and cytotoxicity. The hydrogel exhibited remarkable electrochemical performance with a five-order impedance reduction, sheet resistance of 1.53 kΩ sq^–1, and conductivity of 2.9 S m^–1. OECTs fabricated with the hydrogel showed a threshold voltage of 0.216 V, transconductance of 2.1 mS, and an on/off ratio of 156.7. Live/dead assays confirmed excellent cytocompatibility due to efficient radical scavenging during cross-linking. This 3D conductive hydrogel network, compatible with cellular integration, establishes a foundation for next-generation bioelectronics, including sensors, neural interfaces, and tissue engineering.

Polymer-controlled spacing between NaYF ₄ :Er ³⁺ /Yb ³⁺ nanocrystals and silver nanowires switches up-conversion from quenching to plasmon enhancement and decoupling.

Understanding protein and peptide adsorption at interfaces is crucial to unravel their physiological behavior in cellular environments, where they govern key biological processes, including aggregation mechanisms implicated in neurodegenerative diseases such as Alzheimer’s. In this study, we investigate the adsorption behavior of amyloid-β (Aβ) peptides and their Cu(II) complexes at the water/1,2-dichloroethane (DCE) interface by cyclic voltammetry (CV) and electrochemical impedance techniques, including alternating current (AC) voltammetry. The interface between two immiscible electrolyte solutions (ITIES) serves herein as a biomimetic platform that offers a controlled system to study early-stage adsorption and ion transfer phenomena. We specifically examine Aβ₁₋₁₆ and Aβ₄₋₁₆ peptides, the N-terminal fragments involved in Cu(II) coordination, to deconvolute interfacial electrochemical signals and elucidate the molecular-scale mechanisms of adsorption. The electrochemical data are complemented by molecular dynamics (MD) simulations, enabling a structurally resolved understanding of peptide adsorption and Cu(II) binding at the interface. Our results highlight the impact of interfacial charge regulation, ion-ion interaction, and peptide conformational flexibility on Aβ adsorption, offering mechanistic insights with potential implications for Alzheimer’s disease pathology. By integrating electrochemical techniques with computational modeling, this study establishes a framework for probing and modulating peptide behavior at soft interfaces, paving the way for targeted therapeutic strategies.