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Analytical Applications of Functionalized Self‐Assembled Monolayers on Gold Electrode: Voltammetric Sensing of DOPAC at the Physiological Level
Author(s) -
Raj C. Retna,
Ohsaka Takeo
Publication year - 2002
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200205)14:10<679::aid-elan679>3.0.co;2-t
Subject(s) - monolayer , chemistry , electrode , self assembled monolayer , inorganic chemistry , biochemistry
The voltammetric sensing of a dopamine metabolite, dihydroxyphenyl acetic acid (DOPAC) at the physiological level in the presence of ascorbate (AA) is achieved at the gold electrode modified with electroinacitve functionalized self‐assembled monolayers (SAM) of short chain thiol/disulfides. Substantial decrease in the overpotential for the oxidation of AA is observed at the positively charged monolayer‐modified electrodes. Electrostatic and hydrophobic interactions of negatively charged DOPAC with the positively charged monolayer facilitate its oxidation. The positively charged SAMs successfully separate the voltammetric signals of AA and DOPAC, which are indistinguishable at the bare electrode. The neutral and negatively charged monolayers failed to separate the voltammetric signals of AA and DOPAC. The sensitivities of these electrodes towards the sensing of DOPAC are found to be 0.0162±0.0005 and 0.0353±0.0003 μA/μM at the CYST‐Au and DTH‐Au electrodes, respectively. The CYST‐Au electrode is able to detect as low as 5 μM of DOPAC in the presence of 100 μM of AA whereas the DTH‐Au electrode could sense 1.6 μM of DOPAC.