پديدآورندگان :
Masoumi Mehrnoosh Islamic Azad University , Nasirizadeh Navid Islamic Azad University , Koosha Mojtaba Islamic Azad University
كليدواژه :
Molecularly Imprinted Polymer , Nano–sensor , L , dopa , Carbon ceramic electrode , Central Composite Design.
چكيده فارسي :
Parkinson’s disease is an age related neurological non-genetic disorder associated with the
progressive degeneration of dopamine containing component of the nigro-striated neurons and
the subsequent loss of dopamine in the corpus striatum which affects the mobility and control of
the muscular system skeletal [1]. L-Dopa ([3-(3, 4-dihydroxylphenyl)-L-alanine] is a medication
used to treat Parkinson s disease [2]. This is an unusual amino acid, an important
neurotransmitter, and has been used for the treatment of neural disorders such as Parkinson’s
disease [3]. Accordingly, there is a need for a method to assess and determine a particular drug.
Electrochemical sensor may serve the purpose due to its relative simplicity, selectivity, low-cost
and fast response time [4]. The application of MIPs in electrochemistry is rather recent and was
directed to combine their intrinsic properties to selected electrochemical reactions, in order to
improve the response of the electrode [5]. MIP based sensors compared to natural receptors have
several advantages such as suitable (proper or accurate) selectivity, high robust and reusable, and
is less expensive to prepare [6]. Therefore, use of MIP modified electrodes has been considered
by the researchers [7]. In previous work, we optimized preparation condition of the MIP based
carbon paste electrode for determination L-Dopa [8]. This study presented the ability of
MIP/MWCNT/ carbon ceramic electrode for determination of L-Dopa in solution. Moreover,
comparison between performance of different four electrodes including CCE, MIP/CCE,
MWCNT/CCE and MIP/MWCNT/CCE in measurement of L-Dopa was carried out. Molecularly
imprinted polymer were prepared using L-Dopa as template, methacrylic acid as functional
monomer, ethylene glycol dimethacrylate as cross linker and 2,2–azobis (2–methyl propionitrile)
400
as initiator. The MIP was embedded in the multi walled carbon nanotube modified carbon
ceramic electrode (MWCNT–CCE), which acted as the selective recognition element and pre–
concentrator agent for L-dopa. The effect of different factors such as MIP and MWCNT amounts
at preparation of electrode, also pH of pre-concentration solution and time of L-dopa
accumulation on oxidation current of accumulated L-dopa at electrode surface were investigated
and optimized with Central Composite Design. The optimum conditions for construction of MIP
based sensor including 0.01 g MIP and 0.01 g MWCNT, also best condition for accumulation and
pre-concentration of L-Dopa on sensor surface were found to be solution pH of 2.38 duration
14.5 min. The results showed that MIP/MWCNT/CCE has enough capability for accumulation
and trapping of L-Dopa molecules available in solution. The linear response range and detection
limit were found to be 0.5 to 450.0 nM and 0.13 nM, respectively using the differential pulse
voltammetry method (DPV). The results showed that the proposed sensor is highly selective,
sensitive with a fast response for L-Dopa analysis.
Fig 1: Differential pulse voltammograms of MIP/MWCNT/CCE in a 0.1-M phosphate-buffered solution (pH
7.0) containing different concentrations of L-Dopa. Insets show the plots of the electrocatalytic peak current
as a function of L-Dopa concentration in the range of 0.5–450 nM
