Electrochemical synthesis of molecularly imprinted poly(p-aminobenzene sulphonic acid) on carbon nanodots coated pencil graphite electrode for selective determination of folic acid
Graphical abstract
Introduction
Folic acid (FA) is the synthetic form of folate; vitamin B9 and found in vitamin tablets and fortified foods. FA is vital for making red blood cells, helping rapid cell division and growth, enhancing brain health, age-related hearing loss as well as the synthesis and repair of DNA and RNA. FA is especially important for women who are pregnant or planning to become pregnant since it might help prevent the fetus from developing major congenital deformities of the brain or spine, including neural tube defects, such as spina bifida and anencephaly. Therefore, the selective and sensitive determination of FA in biological system is very important task. However, the analysis of FA in low concentrations is not easy procedure due to the low solubility in acidic conditions, light and temperature sensitive properties, and complex extraction and detection methods [1]. Although there are several analytical techniques for the determination of FA such as high-performance liquid chromatography [2], capillary electrophoresis [3], LC-MS [4], spectrophotometry [5], fluorimetric [6], and flow injection chemiluminescence [7], these methods are time-consuming, expensive and requires complicated pre-treatment steps. On the other hand, the electrochemical methods are very promising way for determination of FA [[8], [9], [10]] due to easy fabrication, low cost and rapid analysis compared to other analytical methods. However, the lack of selectivity is an important aspect in most of the sensors fabricated by electrochemical methods. Therefore, the molecular imprinted polymers (MIPs) based electrochemical sensors have taken great attention recently due to their high selectivity to the target molecule. MIPs are synthetic polymers that have remarkable specific adsorption capability for the analyte detected under interference effect of complex matrix [11]. The molecular imprinting procedure includes the polymerization of a functional monomers in the presence of a template (target) molecule, and then removal of the template creates highly selective recognizing cavities with appropriate size and shape in the polymer backbone [12,13].
Molecular Imprinting Technology (MIT), which concerns formation of selective sites in a polymer matrix with the memory of a template, is a technique to design artificial receptors called MIPs. This technology usually refers to a progress that the template molecules interact with the selected functional monomer to form main host-guest complexes and then a certain amount of cross-linking agent and initiator were added together into the complexes to obtain macromolecule polymers [14]. MIPs have several advantages such as stability at different temperatures and pH’s, relatively inexpensive synthesis and facile preparation compared with natural recognition receptors like antibodies [15,16]. Moreover, to some extent, MIPs are similar to natural recognition receptors due to the high selectivity to the target molecule and the recognition mechanism [17]. These superior features allow MIPs to be used as a recognition element or modifying agents in various nanosensor applications such as ultra-trace level determination of antibiotics [18,19], antioxidants [20], drugs [21,22], and toxic compounds [23,24] with a long lifetime, high reproducibility and repeatability. The conversion of the specific binding to electrical signals is affirmative for this type of sensor applications [25,26].
MIPs could be synthesized by photopolymerization, free radical polymerization or electropolymerization [27]. Comparing to other methods, the electropolymerization have some superior features since the thickness and morphology of the polymer film could be controlled through electropolymerization conditions such as applied cycle number and voltage. However, the relatively low conductivity and electrocatalytic activity of MIPs reduce the sensitivity of the electrochemical sensor [28]. Therefore, the electrodes are modified with conductive nanomaterials especially carbon-based materials and a thin MIP layer formed on the surface of the electrodes increase the conductivity of the sensor [[29], [30], [31], [32]]. Additionally, the electrochemical sensor combined with the MIP could effectively prevent the interference of impurity, which is the major problem of electrochemical detection.
Recently, carbon nanodots (CNDs) have attracted growing interest as a new carbon nanomaterial to fabricate the electrochemical sensor due to the suitable conductivity, small particle size, increasing surface area, easy synthesis, low toxicity and cost [[33], [34], [35], [36]]. CNDs could be synthesized by different methods such as electrochemical oxidation of graphene oxide [37], microwave synthesis [38], and from natural sources like corn [39], orange peel [40] and sugarcane [41]. However, these methods require high temperature and acid usage in large quantities that cause environmental pollution by producing chemical waste. Unlike the other methods, the synthesis of CNDs with electrochemical exfoliation of graphite is a green method that could be carried out at room temperature with high yield [42]. In spite of the superiority of MIPs for electrochemical sensor applications, the most of the studies about the synthesis of MIP for FA sensing are still in initial stage since the large size of FA molecule could inhibit the creation of active sites in the polymer backbone during the polymer formation [43,44].
Herein, a new electrochemical sensor based on MIP, which was synthesized by electropolymerization of p-aminobenzosulphonic acid on CNDs modified pencil graphite electrode, was developed for sensitive and selective recognition of FA. The electrochemical polymerization was achieved by employing of ABSA as a monomer and FA as a template. CNDs were synthesized in an electrochemical cell containing two graphite pencil rods as anode and cathode by applying a constant potential. The double modification of the electrode with CNDs and MIP increased the electroactive surface area, and therefore electrochemical signal of the electrode. To our knowledge, no prior study was done with CNDs and PABSA, which were used at the same time for developing a FA-imprinted electrochemical sensor. Therefore, this paper addresses the need for selective and sensitive determination of FA, so far lacking in the scientific literature. The results showed that the developed sensor provides a successful way in producing effective solution to selective and sensitive determination of FA in drug and human urine samples compared to other analytical techniques as well as rapid analysis time, low cost, and efficient analytical signal.
Section snippets
Reagents and solutions
All chemicals used in study were of analytical reagent grade and used as received without further purification. Folic acid (FA) and p-aminobenzosulfonic acid (ABSA) were purchased from Alfa Aesar (Lancaster, UK). Methotrexate, folinic acid, tetrahydofolic acid, pyridoxine, 5-methyltetrahydrofolate were obtained from Sigma-aldrich (Darmstadt, Germany). Acetonitrile and triethanolamine were purchased from Merck (Darmstadt, Germany). Deionized water from Millipore Milli-Q system (resistivity
Spectral characterizations of CNDs
UV–visible absorption and fluorescence spectra of electrochemically produced CNDs were depicted in Fig. 1. UV–visible spectrum of CNDs exhibited two absorption bands appeared at 283 nm and broad shoulder around 360 nm. When excited at 360 nm, the fluorescence spectrum of CNDs exhibits intense and symmetrical emission peak at 470 nm.
The quantum yield of CNDs was calculated by measuring the integrated fluorescence area of spectrum in aqueous dispersion against quinine sulphate (as a standard one
Conclusion
In this study, a new electrochemical sensor for selective and sensitive determination FA was developed by electro-polymerization of FA-imprinted film on carbon nanodots coated pencil graphite electrode. The experiments revealed that FA-imprinted electrode generated by electro-polymerization of ABSA exhibited a superior selectivity and stability compared to both of the electrodes modified with only carbon nanodots and non-imprinted film. After incubation with FA molecules, the reduction peak
References (65)
- et al.
Folate: methods of analysis
Trends Food Sci. Technol.
(2005) - et al.
Photochemical-fluorimetric determination of folic acid in a multicommutated flow system
Anal. Chim. Acta
(1997) - et al.
Determination of folic acid by chemiluminescence based on peroxomonosulfate-cobalt(II) system
Talanta
(2008) - et al.
Selective electrochemical sensor for folic acid at physiological pH using ultrathin electropolymerized film of functionalized thiadiazole modified glassy carbon electrode
Biosens. Bioelectron.
(2009) - et al.
Single-walled carbon nanotubeionic liquid paste electrode for the sensitive voltammetric determination of folic acid
Sens. Actuators, B
(2008) - et al.
Novel 2,2-[1,2-ethanediylbis(nitriloethylidyne)]-bis-hydroquinone double-wall carbon nanotubepaste electrode for simultaneous determination of epinephrine, uric acid and folic acid
Biosens. Bioelectron.
(2008) - et al.
Electrochemical sensors based on molecularly imprinted polymers
TrAC Trends Anal. Chem
(2004) - et al.
A novel capacitive biosensor for cholesterol assay that uses an electropolymerized molecularly imprinted polymer
Electrochim. Acta
(2010) - et al.
Selective determination of sucrose based on electropolymerized molecularly imprinted polymer modified multiwall carbon nanotubes/glassy carbon electrode
Mater. Sci. Eng. C
(2013) - et al.
On the thermal and chemical stability of molecularly imprinted polymers
Anal. Chim. Acta
(2001)
An azithromycin electrochemical sensor based on an aniline MIP film electropolymerized on a gold nano urchins/graphene oxide modified glassy carbon electrode
J. Electoanal. Chem.
Nano-MIP based sensor for penicillin G: sensitive layer and analytical validation
Sens. Actuators B Chem.
Electrochemical sensor for dodecyl gallate determination based on electropolymerized molecularly imprinted polymer
Sens. Actuators B Chem.
Ultra-trace detection of methamphetamine in biological samples using FFT-square wave voltammetry and nano-sized imprinted polymer/MWCNTs -modified electrode
Talanta
A new carbon paste electrode modified with MWCNTs and nano-structured molecularly imprinted polymer for ultratrace determination of trimipramine: the crucial effect of electrode components mixing on its performance
Biosens. Bioelectron.
Molecularly imprinted polymer nano-sphere/multi-walled carbon nanotube coated glassy carbon electrode as an ultra-sensitive voltammetric sensor for picomolar level determination of RDX
Talanta
Synthesis of nano-sized timolol-imprinted polymer via ultrasonication assisted suspension polymerization in silicon oil and its use for the fabrication of timolol voltammetric sensor
Mater. Sci. Eng. C
A novel electrochemical sensor for selective determination of uranyl ion based on imprinted polymer sol–gel modified carbon paste electrode
Sens. Actuators, B
Generalized electrical conductivity relaxation approach to determine electrochemical kinetic properties for MIECs
Solid State Ion.
Fabrication of an electrochemical molecularly imprinted polymer triamterene sensor based on multivariate optimization using multi-walled carbon nanotubes
J. Electroanal. Chem.
A novel electrochemical 4-nonyl-phenolsensor based on molecularly imprinted poly(o-phenylenediamine-co-o-toluidine)-nitrogen-doped grapheme nano ribbons-ionic liquid composite film
Electrochim. Acta
Development of SudanII sensor based on modified treated pencil graphite electrode with DNA, o-phenylenediamine, and gold nanoparticle bioimprinted polymer
Sens. Actuators B Chem.
Combination of molecularly imprinted polymers and carbon nanomaterials as a versatile biosensing tool in sample analysis: recent applications and challenges
TrAC Trends Anal. Chem. (Reference Ed.)
A facile onepot synthesis of fluorescent carbon dots from degrease cotton for the selective determination of chromium ions in water and soil samples
J. Lumin.
A novel molecularly imprinted electrochemical sensor modified with carbon dots, chitosan, gold nanoparticles for the determination of patulin
Biosens. Bioelectron.
One-pot green synthesis of carbon dots by using Saccharum officinarum juice for fluorescent imaging of bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae) cells
Mater. Sci. Eng. C
Electrochemical sensor for folic acid based on a hyperbranched molecularly imprinted polymer-immobilized sol–gel-modified pencil graphite electrode
Sens. Actuators B Chem.
A novel electrochemical sensor based on poly(p-aminobenzene sulfonic acid)-reduced graphene oxide composite film for the sensitive and selective detection of levofloxacin in human urine
J. Electroanal. Chem.
Sensitive determination of domperidone in biological fluids using a conductive polymer modified glassy carbon electrode
Electrochim. Acta
Poly(p-aminobenzene sulfonic acid)-modified glassy carbon electrode for simultaneous detection of dopamine and ascorbic acid
Sens. Actuators, B
Imprinting molecular recognition sites on multiwalled carbon nanotubes surface for electrochemical detection of insulin in real samples
Electrochim. Acta
General expression of the linear potential sweep voltammogram in the case of diffusionless electrochemical systems
Electroanal. Chem.
Cited by (17)
Recent progress on electroanalytical sensing of small molecules and biomolecules using carbon dots: A review
2023, Journal of Industrial and Engineering ChemistryIon-imprinted CDs-Pc nanohybrid sensor for ratiometric fluorescence and electrochemical detection of Pd(II)
2023, Sensors and Actuators B: ChemicalCitation Excerpt :The imprinted factor (f), which is the ratio of current intensities of Pd-imp@CDs-Pc (ΔIMIP) to N-imp@CDs-Pc (ΔINIP), was also calculated (Table S1). The higher f-value for Pd(II) proves that the designed sensor is more responsive to the target ion compared to the interfering ions [44]. Moreover, when the f-value of a sensor approaches 1.0, it means less imprinting behavior of the sensor and the sensing process is unaffected by the interfering metal ions.
Development of a molecularly imprinted polymer for uric acid sensing based on a conductive azopolymer: Unusual approaches using electrochemical impedance/capacitance spectroscopy without a soluble redox probe
2021, Sensors and Actuators, B: ChemicalCitation Excerpt :During the first potential cycle, an anodic peak of +0.87 V (vs. SCE) was observed and attributed to the oxidation of the primary aromatic amines of the Bismarck Brown Y monomer, starting the polymerization process [33,34]. In the later cycles, there was a decrease in the current magnitude values of the monomer oxidation peak and an increase in the magnitude of the anodic and cathodic currents in the potential range of −0.30 to +0.60 V (vs. SCE), indicating the formation of the polymer on the surface of the FTO electrode [33,35]. At the end of the 40th applied potential cycle, a redox pair with an anodic peak potential of +0.39 V and a cathodic peak potential of −0.05 V was evident, characteristic of the redox equilibrium of azopolymers [36].
Highly sensitive molecular imprinted voltammetric sensor for resveratrol assay in wine via polyaniline/gold nanoparticles signal enhancement and polyacrylamide recognition
2021, Journal of Electroanalytical ChemistryElectropolymerized molecularly imprinted polymers: perceptions based on recent literature for soon-to-be world-class scientists
2021, Current Opinion in ElectrochemistryCitation Excerpt :Pyrrole [1,15–19] is the most common FM, but there are other molecules often used such as o-aminophenol [20–23], o-phenylenediamine [7,24–27], p-aminobenzoic acid [8,9,28], or aniline [29,30]. Other less common examples include 2-mercaptobenzimidazole [6], scopoletin [31], 3-thiophene acetic acid [32,33], m-aminophenylboronic acid [34], nicotinamide [2], dopamine [4,35], gallic acid [36], p-aminothiophenol [37], p-aminobenzene sulphonic acid [38], 5-amino-8-hydroxyquinoline [39], and 2-amino-5-mercapto-1,3,4-thiadiazole [3]. As it can be observed in Figure 2, aniline derivates are quite common.
Electrochemical vitamin sensors: A critical review
2021, TalantaCitation Excerpt :The sensor provided an effective method to investigate VB9 in different natural samples, including broccoli, orange, and tomato juice, among others. Güney applied a molecularly-imprinted ploy(p-aminobenzenesulphonic acid) (ABSA) film onto the surface of carbon nanodot (CND)-modified PGE (MIP/CNDs/PGE) for the detection of VB9 [107]. Differential pulse cathodic stripping voltammetry (DPCSV) was conducted to detect VB9 in PBS (pH 6.2).