How many molecules are required to measure a cyclic voltammogram?

An innovative experimental and mathematical approach in electrochemical sensing for mapping a drug sensor landscape

Our study delves into the examination of an electrochemical sensor through both experimentation and mathematical analysis. The sensor demonstrates the ability to identify a specific antipsychotic medication, namely Chlorpromazine Hydrochloride (CPH), even at incredibly low concentrations, reaching the picomolar level. The identification process relies on the utilization of a Glassy Carbon Electrode (GCE) that has been modified with a ceria-doped zirconia (CeO2/ZrO2) nanocomposite. The nanocomposite was synthesized using the co-precipitation technique and extensively characterized through various analytical methods. It is crucial to detect the presence of CPH as an overdose can result in hyperactivity and severe bipolar disorders among both children and adults. The average size of the nanocomposite was estimated to be 10 nm. The electrode surface area after CeO2/ZrO2 modification of the GCE was found to be 0.059 cm2, which was significantly higher than the electrode surface area of the bare GCE (0.0307 cm2). The limit of detection and limit of quantification for CPH were calculated to be 99.3 pM and 3.010 nM, respectively, with the linear dynamic range of CPH detection found to be between 0.10 and 1.90 μM. The modified sensor electrode was tested on human urine samples with good recoveries and exhibited high selectivity, repeatability, reproducibility, and long-term stability. The experimental voltammograms and the simulated stochastic voltammograms exhibited a fair amount of agreement. Examination of the experimental findings alongside analytical and numerical solutions enables a comprehensive analysis of the factors influencing the outcome of electrochemical measurements. The precise findings can be leveraged for the development of efficient sensing devices for medical diagnostics and environmental monitoring.

Ballistic Brownian Motion of Nanoconfined DNA

Theoretical treatments of polymer dynamics in liquid generally start with the basic assumption that motion at the smallest scale is heavily overdamped; therefore, inertia can be neglected. We report on the Brownian motion of tethered DNA under nanoconfinement, which was analyzed by molecular dynamics simulation and nanoelectrochemistry-based single-electron shuttle experiments. Our results show a transition into the ballistic Brownian motion regime for short DNA in sub-5 nm gaps, with quality coefficients as high as 2 for double-stranded DNA, an effect mainly attributed to a drastic increase in stiffness. The possibility for DNA to enter the underdamped regime could have profound implications on our understanding of the energetics of biomolecular engines such as the replication machinery, which operates in nanocavities that are a few nanometers wide.

Recent Advances in Voltammetry

Recent progress in the theory and practice of voltammetry is surveyed and evaluated. The transformation over the last decade of the level of modelling and simulation of experiments has realised major advances such that electrochemical techniques can be fully developed and applied to real chemical problems of distinct complexity. This review focuses on the topic areas of: multistep electrochemical processes, voltammetry in ionic liquids, the development and interpretation of theories of electron transfer (Butler-Volmer and Marcus-Hush), advances in voltammetric pulse techniques, stochastic random walk models of diffusion, the influence of migration under conditions of low support, voltammetry at rough and porous electrodes, and nanoparticle electrochemistry. The review of the latter field encompasses both the study of nanoparticle-modified electrodes, including stripping voltammetry and the new technique of 'nano-impacts'.