Bogdan Feier

Nouveaux types d'électrodes modifiés pour la détection de métaux lourds et leur application dans le domaine pharmaceutique: Le but de cette thèse a été le développement de capteurs électrochimiques en flux, basés sur l'utilisation du feutre de graphite comme électrode de travail pour l'analyse pharmaceutique et environnementale du cuivre (II) et du zinc (II), deux métaux lourds essentiels pour l'homéostasie de l'organisme humain, mais toxiques en excès. Pour la détection des ions zinciques (II), une cellule d'analyse en flux, bien adaptée pour l'utilisation du feutre de graphite utilisé comme électrode de travail a été élaborée. Les conditions analytiques ont été optimisées et ont conduit à la détection du zinc (II) avec de bonnes sensibilités. Ces résultats montrent l'intérêt de réaliser en flux l'étape de pré-concentration pour augmenter la cinétique d'électrodéposition. Nous avons réalisé une étude complète sur une électrode en feutre de graphite modifiée par réduction d'un sel de diazonium, conduisant à la formation d'un film organique ayant une forte affinité pour les ions cuivriques. L'électrode modifiée combinée avec une étape de pré-concentration en flux permet la réalisation d'un capteur d'ions Cu2+ avec une grande sensibilité et une bonne sélectivité. Nous avons développé, aussi, un capteur électrochimique en flux pour l'analyse des traces d'ions cuivriques à l'aide d'une électrode en feutre de graphite modifiée avec un récepteur capable de complexer de façon sélective les ions de cuivre (II) dans des solutions aqueuses. Enfin, nous avons testé la détection électrochimique du cuivre (II) à l'aide d'électrodes modifiées bidimensionnelles, CPE et SPE. Les résultats préliminaires montrent une bonne capacité de ces électrodes pour la complexation et la détection des ions cuivriques (II).

Introduction: Recent legislative amendments in Romania mandate that qualified pharmacy personnel undertake the centralized compounding of cytotoxic infusions and the handling of cytotoxic drugs. Nevertheless, numerous hospitals continue to depend on inadequately trained nursing staff to perform these critical tasks, thereby heightening the risk of contamination and procedural errors. It is imperative that compounding occurs within a designated room equipped with a laminar airflow hood and that appropriate protective equipment is utilized, adhering to stringent work procedures to mitigate associated risks. This study assesses the outcomes resulting from the implementation of these work procedures and the efficacy of closed transfer systems. Additionally, it compares surface contamination levels of cytotoxic drugs and bacterial presence prior to and following the establishment of these procedures. Methods: Before this study, written work procedures were absent, and the application of closed transfer systems was limited. Comprehensive compounding and administration procedures were thus developed. After a two-year period of implementing these interventions, surface contamination levels were re-evaluated. Surface samples for cytotoxic drug contamination were collected on July 15, 2022, and on May 14, 2024. The presence of four cytotoxic drugs were evaluated initially and seven in the second period from six tested areas. In September 2023, microbial surface contamination inside the hood was assessed using the surface wipe method, then analysed with a commercially available bioluminescence kit and the sterility of the final compounded infusion was checked using the incubation method, using BacT/ALERT ^® PF Plus culture bottles. Results: Wipe samples taken in 2022 indicate contamination with two to three drugs on all tested surfaces. Out of 24 samples collected, 10 tested negative. Contamination levels were detected for 5-fluorouracil, gemcitabine and paclitaxel on different surfaces. However, wipe samples taken in 2024 show contamination levels only for cyclophosphamide and 5-fluorouracil on two surfaces. Out of 42 samples tested, 40 were negative. Three surfaces exhibited no bacterial contamination, while one surface recorded a low level. All three compounded infusion samples for microbial contamination yielded negative results, indicating the absence of bacteria or fungi in the final infusions. Conclusions: The findings indicate that centralized compounding performed by trained pharmacy personnel, in compliance with established work procedures, significantly reduced surface contamination levels and ensured the sterility of the compounded infusions. Similar studies must be conducted across other hospitals to enhance the understanding of contamination dynamics in the compounding of cytotoxic infusions.

A label-free, flexible, and disposable aptasensor was designed for the rapid on-site detection of vancomycin (VAN) levels. The electrochemical sensor was based on lab-printed carbon electrodes (C-PE) enriched with cauliflower-shaped gold nanostructures (AuNSs), on which VAN-specific aptamers were immobilized as biorecognition elements and short-chain thiols as blocking agents. The AuNSs, characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), enhanced the electrochemical properties of the platform and the aptamer immobilization active sites. The developed disposable aptasensor allowed label-free detection of VAN via electrochemical impedance spectroscopy (EIS) across a wide range of concentrations (50–1000 nM), with a limit of detection (LOD) of 1.721 nM. The aptasensor presented good selectivity against some commonly found interferences in human serum and milk and was successfully applied to the analysis of these samples. Graphical Abstract

Introduction: Healthcare-associated infections (HAIs) are associated with increased mortality, antimicrobial resistance, and high antibiotic use. Methods: The characteristics of bacterial resistance and antibiotic consumption in the intensive care unit (ICU) of a clinical hospital in Romania were evaluated. Demographic data of patients, identified bacteria, antibiotics administered, and their sensitivity profiles were collected and analyzed. Results: One hundred and twenty-five patients, with a median age of 68 years, mostly male (60%), were included in the study. More than one-third of the patients died. The deceased patients were older (median age of 74 years), had longer hospitalization (median of 9 days) and bacteria detected (55.3%), and had higher antibiotic consumption than the discharged patients. The most frequent bacteria identified in our cohort were Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa in deceased patients and Klebsiella pneumoniae, Escherichia coli, Staphylococcus hemolyticus, and Enterococcus faecalis in the survived group. The top three antibiotics used were ceftriaxone, metronidazole, and meropenem. Resistance to antibiotics was observed in 44.3% of the deceased group and 37.5% of patients who were discharged (χ² = 5.5, p = 0.0628). Discussion: A positive monotonic association was observed between the number of hospitalization days and the number of antibiotic doses, with a higher correlation coefficient for deceased patients (0.6327, p < 0.0001) than in survived group (0.4749, p < 0.0001). Conclusions and Future Trends: This study provides a real picture of HAIs, the characteristics of bacteria, and the consumption of antibiotics in an ICU of a clinical hospital in Romania. The data obtained are similar to those from other international studies, but further studies are needed to reflect the real situation in Romania.

Synthetic cathinones (SCs) are a group of new psychoactive substances often referred to as “legal highs” or “bath salts”, being characterized by a dynamic change, new compounds continuously emerging on the market. This creates a lack of fast screening tests, making SCs a constant concern for law enforcement agencies. Herein, we present a fast and simple method for the detection of four SCs (alpha-pyrrolidinovalerophenone, N-ethylhexedrone, 4-chloroethcathinone, and 3-chloromethcathinone) based on their electrochemical profiles in a decentralized manner. In this regard, the voltametric characterization of the SCs was performed by cyclic and square wave voltammetry. The elucidation of the SCs redox pathways was successfully achieved using liquid chromatography coupled to (tandem) mass spectrometry. For the rational identification of the ideal experimental conditions, chemometric data processing was employed, considering two critical qualitative and quantitative variables: the type of the electrochemical platform and the pH of the electrolyte. The analytical figures of merit were determined on standard working solutions using the optimized method, which exhibited wide linear ranges and LODs suitable for confiscated sample screening. Finally, the performance of the method was evaluated on real confiscated samples, the resulting validation parameters being similar to those obtained with another portable device (i.e., Raman spectrometer).

The rapid diagnosis of Pseudomonas aeruginosa infection is very important because this bacterium is one of the main sources of healthcare-associated infections. Pseudomonas quinolone signal (PQS) is a specific molecule for quorum sensing (QS) in P. aeruginosa, a form of cell-to-cell bacterial communication and its levels can allow the determination of the bacterial population. In this study, the development of the first electrochemical detection of PQS using screen-printed electrodes modified with carbon nanotubes (CNT-SPE) is reported. The electrochemical fingerprint of PQS was determined using different electrode materials and screen-printed electrodes modified with different nanomaterials. The optimization of the method in terms of electrolyte, pH, and electrochemical technique was achieved. The quantification of PQS was performed using one of the anodic peaks in the electrochemical fingerprint of the PQS on the CNT-SPE. The sensor exhibited a linear range from 0.1 to 15 µM, with a limit of detection of 50 nM. The sensor allowed the selective detection of PQS, with low interference from other QS molecules. The sensor was successfully applied to analysis of real samples (spiked urine and human serum samples, spiked microbiological growth media, and microbiological cultures).

Pseudomonas aeruginosa, an opportunistic Gram-negative bacterium, is one of the main sources of infections in healthcare environments, making its detection very important. N-3-oxo-dodecanoyl L-homoserine lactone (3-O-C₁₂-HSL) is a characteristic molecule of quorum sensing—a form of cell-to-cell communication between bacteria—in P. aeruginosa. Its detection can allow the determination of the bacterial population. In this study, the development of the first electrochemical aptasensor for the detection of 3-O-C₁₂-HSL is reported. A carbon-based screen-printed electrode modified with gold nanoparticles proved to be the best platform for the aptasensor. Each step in the fabrication of the aptasensor (i.e., gold nanoparticles’ deposition, aptamer immobilization, incubation with the analyte) was optimized and characterized using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Different redox probes in solution were evaluated, the best results being obtained in the presence of [Fe(CN)₆]⁴⁻/[Fe(CN)₆]³⁻. The binding affinity of 106.7 nM for the immobilized thiol-terminated aptamer was determined using surface plasmon resonance. The quantification of 3-O-C₁₂-HSL was performed by using the electrochemical signal of the redox probe before and after incubation with the analyte. The aptasensor exhibited a logarithmic range from 0.5 to 30 µM, with a limit of detection of 145 ng mL⁻¹ (0.5 µM). The aptasensor was successfully applied for the analysis of real samples (e.g., spiked urine samples, spiked microbiological growth media, and microbiological cultures).

Healthcare-associated infections can occur in different care units and can affect both patients and healthcare professionals. Bacteria represent the most common cause of nosocomial infections and, due to the excessive and irrational use of antibiotics, resistant organisms have appeared. The most important healthcare-associated infections are central line-associated bloodstream infections, catheter-associated urinary tract infections, surgical site, soft tissue infections, ventilator-associated pneumonia, hospital acquired pneumonia, and Clostridioides difficile colitis. In Europe, some hospitalized patients develop nosocomial infections that lead to increased costs and prolonged hospitalizations. Healthcare-associated infection prevalence in developed countries is lower than in low-income and middle-income countries such as Romania, an Eastern European country, where several factors contribute to the occurrence of many nosocomial infections, but official data show a low reporting rate. For the rapid identification of bacteria that can cause these infections, fast, sensitive, and specific methods are needed, and they should be cost-effective. Therefore, this review focuses on the current situation regarding healthcare-associated infections in Europe and Romania, with discussions regarding the causes and possible solutions. As a possible weapon in the fight against the healthcare-associated infections, the diagnosis methods and tests used to determine the bacteria involved in healthcare-associated infections are evaluated.

Food safety and quality control pose serious issues to food industry and public health domains, in general, with direct effects on consumers. Any physical, chemical, or biological unexpected or unidentified food constituent may exhibit harmful effects on people and animals from mild to severe reactions. According to the World Health Organization (WHO), unsafe foodstuffs are especially dangerous for infants, young children, elderly, and chronic patients. It is imperative to continuously develop new technologies to detect foodborne pathogens and contaminants in order to aid the strengthening of healthcare and economic systems. In recent years, peptide-based sensors gained much attention in the field of food research as an alternative to immuno-, apta-, or DNA-based sensors. This review presents an overview of the electrochemical biosensors using peptides as molecular bio-recognition elements published mainly in the last decade, highlighting their possible application for rapid, non-destructive, and in situ analysis of food samples. Comparison with peptide-based optical and piezoelectrical sensors in terms of analytical performance is presented. Methods of foodstuffs pretreatment are also discussed.