Characterization of gold-thiol-8-hydroxyquinoline self-assembled monolayers for selective recognition of aluminum ion using voltammetry and electrochemical impedance spectroscopy.
Gold electrode surface is modified via covalent attachment of a synthesized thiol functionalized with 8-hydroxyquinoline, p-((8-hydroxyquinoline)azo) benzenethiol (SHQ), for the first time. The behavior of the nanostructured electrode surface (Au-SHQ) is characterized by electrochemical techniques including cyclic and differential pulse voltammetry (CV and DPV), and electrochemical impedance spectroscopy (EIS). The modified surface is stable in a wide range of potentials and pHs. A surface pKa of 6.0±0.1 is obtained for Au-SHQ electrode using surface acid/base titration curves constructed by CV and EIS measurements as a function of pH. These results helped to determine the charge state of the surface as a function of pH. The gold modified electrode surface showed good affinity for sensing the Al(III) ion at pH 5.5. The sensing process is based on (i) accumulation and complex formation between Al(III) from the solution phase and 8HQ function on the Au electrode surface (recognition step) and (ii) monitoring the impedance of the Au-SHQ-Al(III) complex against redox reaction rate of parabenzoquinone (PBQ) (signal transduction step). The PBQ is found to be a more suitable probe for this purpose, after testing several others. Thus, the sensor was tested for quantitative determination of Al(III) from the solution phase. At the optimized conditions, a linear response, from 1.0×10(-11) to 1.2×10(-5) M Al(III) in semi-logarithmic scale, with a detection limit of 8.32×10(-12) M and mean relative standard deviation of 3.2% for n=3 at 1.0×10(-7) M Al(III) is obtained. Possible interferences from coexisting cations and anions are also studied. The results show that many ions do not interfere significantly with the sensor response for Al(III). Validity of the method and applicability of the sensor are successfully tested by determination of Al(III) in human blood serum samples.
Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran. Electronic address: rkarimi@sci.ui.ac.ir.
Reza Karimi
RK
Shervedani
Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.
Zeinab
Z
Rezvaninia
Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.
Hassan
H
Sabzyan
Department of Chemistry, University of Isfahan, Isfahan 81746-73441, Iran.
Hassan Zali
HZ
Boeini
D000327:Adsorption; D000535:Aluminum / Q000097:blood / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D016227:Benzoquinones / Q000737:chemistry; D058266:Dielectric Spectroscopy; D004563:Electrochemistry; D004566:Electrodes; D006046:Gold / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006912:Hydroxyquinolines / Q000737:chemistry*; D010084:Oxidation-Reduction; D011804:Quinolines / Q000737:chemistry*; D013499:Surface Properties
D001391:Azo Compounds; D016227:Benzoquinones; D006912:Hydroxyquinolines; D011804:Quinolines; C004532:quinone; D006046:Gold; D000535:Aluminum; C037219:quinoline
8-Hydroxyquinolin; Aluminum ion detection; Electrochemical impedance spectroscopy; Human blood serum; Self-assembled monolayers; Voltammetry