Voltammetric analysis of nitroxoline in tablets and human serum using modified carbon paste electrodes incorporating mesoporous carbon or multiwalled carbon nanotubes

Abstract

Mesoporous carbon (MC) was synthesized using a mesoporous SiO 2 template material (SBA-15) and sucrose as the carbon source. SBA-15, MC as well as commercially obtained multi-walled carbon nanotubes (MWCNTs) were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 sorption isotherms and electrochemical impedance spectra. A carbon paste (CP) electrode modified with either MC or MWCNTs was used as a sensor for sensitive and selective determination of the nitroxoline drug. Using cyclic voltammetry, linear sweep and square-wave adsorptive stripping voltammetry, nitroxoline was found to oxidize via one developed peak at MWCNT/ CP and MC/CP electrodes compared to unmodified one. This is attributed to the stronger adsorptive character, lower charge transfer resistances and higher electrocatalytic activities of modified CP electrodes than the unmodified CP electrode. A well-defined peak and high current response were observed in a B-R universal buffer (pH 2.5) following preconcentration of nitroxoline by adsorption accumulation at À0.2 V (vs. Ag/AgCl/KCl s ). Limits of detection of 3.0 Â 10 À11 , 1.5 Â 10 À11 and 3.0 Â 10 À12 M nitroxoline, were obtained using the unmodified CP, MWCNT/CP and MC/CP electrodes, respectively. The utility of these sensors was examined for the determination of nitroxoline in its pharmaceutical dosage form (Nibiol® tablets) and human serum.

Protonation–Activity Relationship of Bioinspired Ionizable Glycomimetics for the Growth Inhibition of Bacteria

“…Both NQ and ciprofloxacin are fluoroquinolone antibacterial agents, which display the same antibacterial activity by the inhibition of the bacterial DNA synthesis. − To unambiguously demonstrate the pH-responsive release behavior of three types of nanoparticles, we further chose ciprofloxacin as a guest molecule. The same results were obtained when observing the release process of ciprofloxacin at pH 7.4.…”

Recent Trends on Electrochemical Sensors Based on Ordered Mesoporous Carbon

“…OMC materials by themselves are attractive electrode substrates for electrochemical sensing owing to their attractive properties (large conducting surface area, regular and widely open nanostructure, catalytic edge-plane-like sites, or oxygenated surface functions). Table 1 gathers all applications of unmodified OMC-based electrochemical sensors reported to date [ 23 , 25 , 43 , 44 , 45 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , <...>…”

“…Several drugs and biologically-relevant molecules, as well as some pesticides, have been detected after accumulation at OMC-modified electrodes. The preconcentration mechanism is not always described but it is possibly due to hydrophobic and/or π–π interactions as most of the investigated species possess aromatic moieties in their molecular structure (i.e., phenol [ 57 , 59 , 72 , 79 , 98 ], nitrophenyl or nitroaromatic groups [ 64 , 78 , 85 , 87 , 89 , 90 ], catechol [ 65 , 97 ], or other aromatic groups [ 60 , 96 , 99 ]). Due to the non-specific nature of these interactions, the sensor selectivity is expected to be rather poor (only controlled by the detection potential) and thus limited in real environmental monitoring (except for spiked samples) but useful to the analysis of drug formulations (pharmaceutical tablets) or foodstuffs, for instance.…”

“…These applications were mostly based on OMC film electrodes ( Table 1 ), but also on carbon paste [ 59 , 89 ] and ionic liquid-based carbon paste electrodes [ 57 , 60 , 65 , 92 , 97 ]. In this last case, the ionic liquid serves as a binder but it could also contribute to accumulate the target analyte.…”

A magnetic core–shell Fe3O4@SiO2/MWCNT nanocomposite modified carbon paste electrode for amplified electrochemical sensing of amlodipine and hydrochlorothiazide

“…In order to overcome these problems, a fascinating and effective way is to modify it by mixing with some other unique substances. [21][22][23] Recently, room temperature ionic liquids (RTILs) have received great attention due to their specic characteristics such as negligible vapor pressure, high polarity, high solvation, non-coordination and non-ammability, and they are used as acidic catalysts in many reactions by reason of their tunable acidity. 24 As a novel "green" solvent, RTILs have been used in synthetic chemistry, materials science, catalytic chemistry and electrochemistry.…”