Dufen Hu

Facile synthesis of the necklace-like graphene oxide-multi-walled carbon nanotube nanohybrid and its application in electrochemical sensing of Azithromycin

A novel electrochemical platform was designed for the determination of Azithromycin (Azi), a widely used macrolide antibiotic, by combining the hydrophilic properties of graphene oxide (GO) and the excellent electronic and antifouling properties of multi-walled carbon nanotubes (MWCNTs). Stable MWCNTs aqueous dispersion has been prepared using GO nano-sheets as surfactant and the obtained GO-MWCNTs nanohybrid was characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy, which confirmed that GO nano-sheets were attached onto the wall of MWCNTs to form a necklace-like structure. 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.

Synthesis of novel chiral L-leucine grafted PEDOT derivatives with excellent electrochromic performances

Two amino acid-functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives, poly(N-(tert-butoxycarbonyl)-L-leucyl(3,4-ethylenedioxythiophene-2′-yl)methylamide) (PEDOT–Boc–Leu) and poly(L-leucyl(3,4-ethylenedioxythiophene-2′-yl)methylamide) (PEDOT–Leu) were synthesized electrochemically via potentiostatic polymerization of corresponding monomers N-(tert-butoxycarbonyl)L-leucyl(3,4-ethylenedioxythiophene-2′-yl)methylamide (EDOT–Boc–Leu) and L-leucyl(3,4-ethylenedioxythiophene-2′-yl)methylamide (EDOT–Leu), which were synthesized by grafting Boc-L-leucine and L-leucine into a 3,4-ethylenedioxythiophene (EDOT) side chain. The electrochemical behaviors, structural characterization, circular dichroism, spectroscopic properties, surface morphology, electrochromic properties and thermal stabilities of PEDOT–Boc–Leu and PEDOT–Leu films were systematically investigated. These L-leucine grafted PEDOT derivatives displayed excellent reversible redox activities, rough and compact surface, and good thermal stability. The circular dichroism spectra suggested the chirality of these polymers. Importantly, the introduction of the L-leucine group enhanced the electrochromic properties of PEDOT and resulted in high contrast ratios (ΔT% = 49% at 600 nm for PEDOT–Boc–Leu) and high coloration efficiencies (431 cm2 C−1 at 960 nm for PEDOT–Leu). Satisfactory results implied that the obtained polymer films can probably be further developed in various applications, such as electrochromic devices, optical displays and chiral recognition.

Electrosynthesis and characterization of aminomethyl functionalized PEDOT with electrochromic property

We herein report the electrosynthesis of an aminomethyl functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) derivative, poly(2′-aminomethyl-3,4-ethylenedioxythiophene) (PEDOT-MeNH2), in CH2Cl2-Bu4NPF6 (0.1 mol·L-1) system containing 2% boron trifluoride diethyl etherate (BFEE). The electrochemical behavior, structure characterization, thermal properties and surface morphology of this novel polymer were systematically investigated by cyclic voltammetry (CV), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG) and scanning electron microscopy (SEM), respectively. Electrochemistry results demonstrated that PEDOT-MeNH2 film displayed good redox properties and high electrochemical stability. Besides, PEDOT-MeNH2 films exhibited the electrochromic nature with obvious color changing from purple in the reduced form to blue upon oxidation. By further investigation, kinetic studies revealed that PEDOT-MeNH2 film had decent contrast ratio (41.8%), favorable coloration efficiency (152.1 cm2·C-1), low switching voltages and moderate response time (2.4 s). Satisfactory results implied that the obtained PEDOT-MeNH2 film is a promising optoelectronic material and holds promise for electrochromic devices and display applications.

Synthesis and characterization of D-/L-methionine grafted PEDOTs for selective recognition of 3,4-dihydroxyphenylalanine enantiomers

Two pairs of amino-acid functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives, namely, poly(N-(tert-butoxycarbonyl)-L-methionyl (3,4-ethylenedioxythiophene-2’-yl)methylamide) (L-PEDOT-Boc-Met) and poly(N-(tert-butoxycarbonyl)-D-methionyl (3,4-ethylenedioxythiophene-2’-yl)methylamide) (D-PEDOT-Boc-Met); poly(L-methionyl (3,4-ethylenedioxythiophene-2’-yl)methylamide) (L-PEDOT-Met) and poly(D-methionyl (3,4-ethylenedioxythiophene-2’-yl)methylamide) (D-PEDOT-Met) were synthesized via chemical oxidative polymerization of corresponding monomers. The structural characterization, spectroscopic properties and thermal stability of these monomers and polymers were systematically explored by FTIR spectra, Raman spectra, XRD spectra, UV-Vis spectra and thermogravimetric analysis. As chiral electrode materials, these polymers were employed to successfully recognize 3,4-dihydroxyphenylalanine (DOPA) enantiomers by cyclic voltammetry (CV) in sulphuric acid solution. The measurement results reveal that the tendency was hetero-chiral interaction between L-PEDOT-Met/PVA/GCE and D-DOPA, D-PEDOT-Met/PVA/GCE and L-DOPA, respectively. Also, the mechanism of chiral discrimination was discussed. All the results implied that the combination of electrochemical molecular recognition technology and chiral PEDOT materials can be a promising approach for chiral recognition and may open new opportunities for facile, biocompatible, sensitive and robust chiral assays in biochemical applications.