Bidimensional Spectroelectrochemistry with Tunable Thin-Layer Thickness.

Bidimensional spectroelectrochemistry (Bidim-SEC) is an instrumental technique that provides operando UV/vis absorption information on electrochemical processes from two different points of view, using concomitantly a parallel and a normal optical configuration. The parallel configuration provides information about chemical species present in the diffusion layer, meanwhile the normal arrangement supplies information about changes occurring both in the diffusion layer and, mainly, on the electrode surface. The choice of a suitable cell to perform Bidim-SEC experiments is critical, especially while working under a thin-layer regime. So far, most of the proposed Bidim-SEC cells rely on the use of spacers to define the thin-layer thickness, which leads to working with constant thickness values. Herein, we propose a novel Bidim-SEC cell that enables easy-to-use micrometric control of the thin-layer thickness using a piezoelectric positioner. This device can be used for the study of complex interfacial systems and also to easily measure the key parameters of an electrochemical process. As a proof of concept, the study of the roughening of a gold electrode in KCl medium is performed, identifying key steps in the passivation and nanoparticle generation on the gold surface.

Raman, UV-Vis Absorption, and Fluorescence Spectroelectrochemistry for Studying the Enhancement of the Raman Scattering Using Nanocrystals Activated by Metal Cations.

Raman signal enhancement is fundamental to develop different analytical tools for chemical analysis, interface reaction studies, or new materials characterization, among others. Thus, phenomena such as surface-enhanced Raman scattering (SERS) have been used for decades to increase the sensitivity of Raman spectroscopy, leading to a huge development of this field. Recently, an alternative method to SERS for the amplification of Raman signals has been reported. This method, known as electrochemical surface oxidation-enhanced Raman scattering (EC-SOERS), has been experimentally described. However, to date, it has not yet been fully understood. In this work, new experimental data that clarify the origin of the Raman enhancement in SOERS are provided. The use of a complete and unique set of combined spectroelectrochemistry techniques, including time-resolved operando UV-vis absorption, fluorescence, and Raman spectroelectrochemistry, reveals that such enhancement is related to the generation of dielectric or semiconductor nanocrystals on the surface of the electrode and that the interaction between the target molecule and the dielectric substrate is mediated by metal cations. According to these results, the interaction metal electrode-nanocrystal-metal cation-molecule is proposed as being responsible for the Raman enhancement in Ag and Cu substrates. Elucidation of the origin of the Raman enhancement will help to promote the rational design of SOERS substrates as an attractive alternative to the well-known SERS phenomenon.

Simultaneous Scanning Electrochemical Microscopy and UV-Vis Absorption Spectroelectrochemistry.

The combination of instrumental techniques allows obtaining precise and reliable information about the reactions taking place at the electrode/solution interface. Although UV-Vis absorption spectroelectrochemistry (UV-Vis SEC) provides a molecular insight about the species involved in the electrode process, obtaining information about the redox state of the products generated in this process is not always accessible by this technique. In this sense, scanning electrochemical microscopy (SECM) has a clear advantage, since it provides additional information on the oxidation state of the intermediates/products. Therefore, the combination of these two techniques facilitates obtaining a more complete picture of the electrochemical reaction studied from two different points of view, but under exactly the same experimental conditions. In this work, the combination of UV-Vis SEC in parallel configuration and SECM is carried out for the first time. This new technique allows distinguishing between those species that are electrochemically active and, at the same time, exhibit changes in the UV-Vis absorption spectra during the electrochemical reaction. The new experimental setup is first validated using ferrocenemethanol as a standard probe, concomitantly obtaining spectroscopic and electrochemical information that accurately describes the oxidation process. Finally, the strength of this combined technique is demonstrated by studying the antioxidant activity of o-vanillin (o-HVa) in the presence of electrogenerated superoxide. The information extracted from the new UV-Vis SEC/SECM technique makes it possible to identify, beyond any doubt, not only the origin of the electrochemical signals recorded in the SECM tip but also to evaluate the antioxidant effect of o-HVa at different concentrations.

Thoracic Osteomyelitis and Eustachian Valve Endocarditis: A Case Report and Literature Review.

Infective endocarditis and vertebral osteomyelitis are rare infections, most commonly caused by methicillin-sensitive Staphylococcus aureus (MSSA). The eustachian valve is an embryological remnant of the inferior vena cava that has the potential to harbor a nidus leading to infective endocarditis. Eustachian valve endocarditis has been documented in the literature on less than 50 occasions and has yet to be documented in the presence of concomitant vertebral osteomyelitis. In this case, we present a 43-year-old male presenting with vertebral osteomyelitis caused by methicillin-resistant Staphylococcus aureus (MRSA). Persistent bacteremia prompted the identification of vegetative growth on a eustachian valve remnant. This case helps mend the gap in the literature by documenting the treatment considerations in a patient with eustachian valve endocarditis in the presence of osteomyelitis caused by MRSA.

Atypical Neuroleptic Malignant Syndrome in the Setting of Quetiapine Overdose: A Case Report and Review of the Literature.

Neuroleptic malignant syndrome (NMS) is a rare and life-threatening emergency. The condition is largely iatrogenic and is often precipitated by medications such as antipsychotics. First-generation antipsychotics are more likely to cause NMS than second-generation antipsychotics. The literature lacks an objective measure for NMS diagnosis. Instead, the diagnosis relies largely on the recognition of characteristic symptoms in the presence of an inciting medication. Additional challenges exist with concomitant disease processes and toxicities that may distort the clinical picture. Here, we report a case of a 44-year-old Caucasian man who presented with atypical NMS in the setting of quetiapine overdose. The patient remained uncharacteristically afebrile throughout his admission. Although the patient recovered, extended delays in identification and management can contribute to an increased risk of morbidity and mortality.

Determination of uric acid in synthetic urine by using electrochemical surface oxidation enhanced Raman scattering.

In this work, a new and easy methodology to determine uric acid in relevant samples using Raman spectroelectrochemistry is presented. The spectroelectrochemistry experiment is based on the in-situ formation of a suitable substrate that enables the enhancement of the Raman signal of an analyte during the oxidation stage of a silver electrode. This phenomenon is known as electrochemical surface oxidation enhanced Raman scattering (EC-SOERS) and has proved to be useful in quantitative analysis using disposable screen printed electrodes. The successful combination of EC-SOERS with PARAFAC analysis allows the determination of uric acid in a relevant complex sample avoiding the use of standard addition method and without using a baseline correction, which simplifies the application of such methodology in routine analysis.