A cost-effective method for the sensitive detection of levofloxacin using a 3D composite electrode composed of nail polish, graphite and aluminium oxide.

The potential impact on human health and the environment has spurred significant interest in detecting and quantifying pharmaceutical compounds across various matrices, from environmental to biological samples. Here, we present an electrochemical approach for determining levofloxacin in drug, synthetic urine, water, and breast milk samples. An affordable sensor was constructed using 3D printing and composite material based on nail polish, graphite, and aluminum oxide. The conductive composite material was characterized spectroscopically, electrochemically, and by imaging techniques. Subsequently, an electrochemical method based on square wave voltammetry was optimized and applied. The method exhibited good sensitivity (5.11 ± 0.0912 µA L µmol-1 cm-2) and enhanced stability (RSD = 7.2%), with electrochemical responses correlating with the concentration of levofloxacin in the samples tested, yielding recovery values in the range of 98 to 111%. The developed method demonstrated a robust linear working range from 2 to 100 µmol L-1 and a nanomolar detection limit of 128 nmol L-1, rendering it suitable for quantitative analysis. The sensor also shows promise as a platform for the sensitive detection of pharmaceutical compounds, contributing to greater safety and sustainability in these domains.

Electrochemical monitoring of levofloxacin using a silver nanoparticle-modified disposable device based on a lab-made conductive ink.

The emergence of bacteria genetically resistant to first- and second-generation fluoroquinolones has resulted in increased consumption of levofloxacin (LEV) in human and veterinary medicine. In this regard, the development of low cost and good sensitivity electrochemical devices has been highly required. Thus, in this work, we propose the development of a disposable electrochemical device (DED) using a lab-made conductive ink based on graphite powder and nail polish immobilized on a rigid polyvinyl chloride support (transparent sheet). Additionally, a simple and quick protocol for the electrodeposition of silver nanoparticles was used in order to improve the electroanalytical performance of the sensor (2.75-fold). A differential pulse voltammetry (DPV) method was optimized and the sensor was applied for LEV monitoring in pharmaceutical formulation samples, synthetic urine and simulated body fluid. The method showed a wide linear working range ranging from 0.5 to 50 µmol L-1 and a detection limit of 68.3 nmol L-1. Furthermore, the precision was adequate (RSD < 4.7%), while the accuracy was evaluated through spiked samples with percent recovery ranging from 93 to 103%. The sensor was also shown to be selective for LEV against other electroactive antibiotic species, thus demonstrating suitable characteristics for electroanalytical applications.

A pencil graphite-based disposable device for electrochemical monitoring of sulfanilamide in honey and water samples.

The present paper reports a simple, fast, and inexpensive process of manufacturing a disposable pencil graphite electrode (PGE) from widely available materials, which showed a reproducibility of at least 7.5%. The electrode was compared to the commercial glassy carbon electrode (GCE) and showed superior electroanalytical performance for sulfanilamide (SFA) with approximately 3.9-fold higher current density. Additionally, a displacement of the oxidation peak from approximately 80 mV to more cathodic regions was observed. Therefore, a method based on square wave voltammetry (SWV) was developed for the determination of the antimicrobial SFA in honey and tap water samples using the proposed sensor. The optimized method presented good detectability (LOD = 2.37 µmol L-1), with excellent precision and accuracy (relative standard deviation < 4.2%) and percent recovery from spiked samples ranging from 92 to 97%. In addition, the sensor did not suffer significant interference from sample matrix components and other commonly evaluated antimicrobials, which demonstrates the potential of these electrodes for implementation in routine analysis and quality control.