Levofloxacin capped Ag-nanoparicles: A new highly selective sensor for cations under joint experimental and DFT investigation

Facile Synthesis of Ag/AgVO3/N-rGO Hybrid Nanocomposites for Electrochemical Detection of Levofloxacin for Complex Biological Samples Using Screen-Printed Carbon Paste Electrodes

Silver vanadate nanorods (β-AgVO₃) with silver nanoparticles (Ag-NPs) decorated on the surface of the rods were synthesized by using simple hydrothermal technique and later anchored onto nitrogen-doped reduced graphene oxide (N-rGO) to make a novel nanocomposite. Experimental analyses were carried out to identify the electronic configuration by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analysis, which revealed monoclinic patterns of the C12/m1 space group with Wulff construction forming beta silver vanadate (β-AgVO₃) crystals with optical density and phase transformations. Ag nucleation showed consistent results with metallic formation and electronic changes occurring in [AgO₅] and [AgO₃] clusters. Transmission electron microscopy and field-emission scanning electron microscopy with elemental mapping and EDX analysis of the morphology reveals the nanorod structure for β-AgVO₃ with AgNPs on the surface and sheets for N-rGO. Additionally, a novel electrochemical sensor is constructed by using Ag/AgVO₃/N-rGO on screen-printed carbon paste electrodes for the detection of antiviral drug levofloxacin (LEV) which is used as a primary antibiotic in controlling COVID-19. Using differential pulse voltammetry, LEV is determined with a low detection limit of 0.00792 nm for a linear range of 0.09-671 μM with an ultrahigh sensitivity of 152.19 μA μM^-1 cm^-2. Furthermore, modified electrode performance is tested by real-time monitoring using biological and river samples.

Voltammetric determination of levofloxacin using silver nanoparticles deposited on a thin nickel oxide porous film

The authors describe a simplified chemical precipitation method and silver mirror reaction to synthesize a nanocomposite consiting of silver nanoparticles on a thin and porous nickel oxide film. Placed on a glassy carbon electrode (GCE), it allows for the determination of levofloxacin (LEV) via square wave voltammetry (SWV). Under optimal detection conditions, the voltammetric signal (typically measured at around 0.96 V vs. SCE) increases linearly in the 0.25-100 μM LEV concentration range. And the detection limit was calculated as 27 nM (at S/N = 3). The sensor is highly selective, stable and repeatable. It was applied to the determination of LEV in spiked human serum samples, and the satisfactory results confirm the applicability of this sensor to practical analyses. Graphical abstract Schematic of a two-step method to synthesize a nanocomposite consisting of nickel oxide porous thin-film supported silver nanoparticles. The composite was used for improved voltammetric determination of levofloxacin.

Rapid Colorimetric Detection of Cartap Residues by AgNP Sensor with Magnetic Molecularly Imprinted Microspheres as Recognition Elements

The overuse of cartap in tea tree leads to hazardous residues threatening human health. A colorimetric determination was established to detect cartap residues in tea beverages by silver nanoparticles (AgNP) sensor with magnetic molecularly imprinted polymeric microspheres (Fe₃O₄@mSiO₂@MIPs) as recognition elements. Using Fe₃O₄ as supporting core, mesoporous SiO₂ as intermediate shell, methylacrylic acid as functional monomer, and cartap as template, Fe₃O₄@mSiO₂@MIPs were prepared to selectively and magnetically separate cartap from tea solution before colorimetric determination by AgNP sensors. The core-shell Fe₃O₄@mSiO₂@MIPs were also characterized by FT-IR, TEM, VSM, and experimental adsorption. The Fe₃O₄@mSiO₂@MIPs could be rapidly separated by an external magnet in 10 s with good reusability (maintained 95.2% through 10 cycles). The adsorption process of cartap on Fe₃O₄@mSiO₂@MIPs conformed to Langmuir adsorption isotherm with maximum adsorption capacity at 0.257 mmol/g and short equilibrium time of 30 min at 298 K. The AgNP colorimetric method semi-quantified cartap ≥5 mg/L by naked eye and quantified cartap 0.1–5 mg/L with LOD 0.01 mg/L by UV-vis spectroscopy. The AgNP colorimetric detection after pretreatment with Fe₃O₄@mSiO₂@MIPs could be successfully utilized to recognize and detect cartap residues in tea beverages.