Electrochemical Sensors Based On Novel Carbon Nanocomposites For Detection Of Macrolides And Phenolic Drugs

Currently, the traditional analytical methods such as biological analysis, electrophoresis, fluorescence spectroscopy, ultraviolet spectroscopy, high performance liquid chromatography, gas chromatography, chromatography-mass spectrometry, become the mainstream, which have been widely used in drug detection, and effective pharmaceutical ingredients and drug residues analysis. These techniques show high sensitivity, but they require expensive instruments, time-consuming pretreatment steps, skilled operators and large quantity of organic solvents. Moreover, these techniques can not be used for in situ assay. Electrochemical methods provide useful alternatives due to their simplicity, high sensitivity, good stability, low-cost instrumentation, and on-site monitoring. Thus, the advantages of electrochemical sensors in pharmaceutical analysis are increasingly recognized by researcher. In the present work, due to the excellent properties of GO (large surface area and high adsorption capability) and MWCNTs (excellent electrocatalytic activity), GO and MWCNTs based materials have been used to fabricate a series of macrolides antibiotics and phenols drug electrochemical sensors. Specific content is as follows:(1) A stable aqueous dispersion of hydrophobic GO-MWCNTs nanohybrid was prepared by sonication methods without assistance of any surfactant. Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM) suggested that GO nano-sheets were attached onto the wall of MWCNTs to form a necklace-like structure. The GO-MWCNTs nanohybrid was then used to fabricate a novel electrochemical sensor for Azi. Electrochemical results obviously reveal that the oxidation peak currents of Azi obtained at the GC electrode modified with GO-MWCNTs hybrid are much higher than those at the MWCNTs/GC, GO/GC and bare GC electrodes. Under optimized conditions, the anodic peak current was linear to the concentration of Azi in the range from 0.1 to 10 μM with the detection limit of 0.07 μM. To further validate its possible application, the proposed method was successfully used for the determination of Azi in pharmaceutical formulations with satisfactory results.(2) GO/PEDOT nanocomposites were synthesized via a liquid-liquid interfacial polymerization method. The synthesized composites were characterized by using Fourier transform infrared (FT-IR), Raman spectroscopic studies, EIS, and their morphology were analyzed by TEM. Characterization and surface morphology results indicated that PEDOT with a nanorods-like structure successfully anchored on the surface of GO sheets. Then the obtained GO/PEDOT nanocomposites were utilized to modify glassy carbon electrode and designed for the trace level sensing of rutin and the oxidation mechanism of rutin was explored. Electrochemical results revealed that the GO/PEDOT nanocomposites modified electrode exhibited larger oxidation peak currents of rutin than pure PEDOT and GO. Under optimized conditions, the anodic peak current was linear to the concentration of rutin in the range from 0.004 to 60 uM with the detection limit of 0.00125 μM. To further validate its possible application, the proposed method was successfully used for the determination of rutin in pharmaceutical formulations with satisfactory results.(3) Compared with GO, MWCNTs based nanomaterials modified electrode can exhibit stronger catalytic to some certain drug molecules, therefore, MWCNTs/PEDOT nanofibers were synthesized through an interfacial polymerization technique. The synthesized composites were characterized by using FT-IR, Raman spectroscopic, EIS, and TEM. Characterization and surface morphology results indicated that PEDOT film successfully anchored on the surface of MWCNTs. Then the obtained MWCNTs/PEDOT nanocomposites were utilized to modify glassy carbon electrode and designed for the trace level sensing of magnolol. By optimizing the detection of experimental conditions, when the pH of buffer solution was 7.0, the fabricated electrochemical sensor can get the best detection results. Under optimized conditions, the anodic peak current was linear to the concentration of magnolol in the range from 0.1 to 10 μM with the detection limit of 0.003 μM. Then the electrochemical sensor can be applied to the determination of the content of magnolol in Magnolia Bark Extraction.(4) Nanostructured GO-MWCNTs were incorporated into PEDOT matrix for the synthesis of GO-MWCNTs/PEDOT nanocomposite by using one-step electropolymerization method. Then the obtained nanocomposite was used to fabricate the diethylstilbestrol (DES) electrochemical sensor. The parameters of constructed electrochemical sensor were optimized, it indicated that when the pH of buffer solution was 7.0 and the accumulation time was 120 s, the electrochemical sensor can get the best detection results. Under optimized conditions, the anodic peak current was linear to the concentration of DES in the range from 0.01 to 20 μM with the detection limit of 0.003 μM. To further validate its possible application, the proposed method was successfully used for the determination of DES in pharmaceutical formulations with satisfactory results.