Design and Development of a Nanostructure Sensor for Determination of LDopawith MIP and Carbon Ceramic Composite

Parkinson’s disease is an age related neurological non-genetic disorder associated with theprogressive degeneration of dopamine containing component of the nigro-striated neurons andthe subsequent loss of dopamine in the corpus striatum which affects the mobility and control ofthe muscular system skeletal [1]. L-Dopa ([3-(3, 4-dihydroxylphenyl)-L-alanine] is a medicationused to treat Parkinson s disease [2]. This is an unusual amino acid, an importantneurotransmitter, and has been used for the treatment of neural disorders such as Parkinson’sdisease [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-costand fast response time [4]. The application of MIPs in electrochemistry is rather recent and wasdirected to combine their intrinsic properties to selected electrochemical reactions, in order toimprove the response of the electrode [5]. MIP based sensors compared to natural receptors haveseveral advantages such as suitable (proper or accurate) selectivity, high robust and reusable, andis less expensive to prepare [6]. Therefore, use of MIP modified electrodes has been consideredby the researchers [7]. In previous work, we optimized preparation condition of the MIP basedcarbon paste electrode for determination L-Dopa [8]. This study presented the ability ofMIP/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. Molecularlyimprinted polymer were prepared using L-Dopa as template, methacrylic acid as functionalmonomer, ethylene glycol dimethacrylate as cross linker and 2,2–azobis (2–methyl propionitrile) as initiator. The MIP was embedded in the multi walled carbon nanotube modified carbonceramic 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 amountsat preparation of electrode, also pH of pre-concentration solution and time of L-dopaaccumulation on oxidation current of accumulated L-dopa at electrode surface were investigatedand optimized with Central Composite Design. The optimum conditions for construction of MIPbased sensor including 0.01 g MIP and 0.01 g MWCNT, also best condition for accumulation andpre-concentration of L-Dopa on sensor surface were found to be solution pH of 2.38 duration14.5 min. The results showed that MIP/MWCNT/CCE has enough capability for accumulationand trapping of L-Dopa molecules available in solution. The linear response range and detectionlimit were found to be 0.5 to 450.0 nM and 0.13 nM, respectively using the differential pulsevoltammetry method (DPV). The results showed that the proposed sensor is highly selective,sensitive with a fast response for L-Dopa analysis.

کلیدواژه ها:

Molecularly Imprinted Polymer ، Nano–sensor ، L-dopa ، Carbon ceramic electrode ، Central Composite Design