Electropolymerization Of O-phenylenediamine Research Articles

Selective and sensitive molecularly imprinted polymer-based electrochemical sensor for detection of deltamethrin

Electrochemical sensors have a broad range of industrial applications due to their sensitivity, speed, and cost-effectiveness. These sensors enable the continuous monitoring and control of critical parameters in various industrial processes. For instance, they are essential in food safety, environmental monitoring, biomedical applications, and pharmaceutical production. In the food industry, electrochemical sensors facilitate the rapid and reliable detection of contaminants and pathogens in food products, thus enhancing product quality and consumer safety. An electrochemical sensor was developed with the molecularly imprinted polymer (MIP) technique to detect deltamethrin with high sensitivity and selectivity. The sensor was fabricated by electrodeposition of Co3O4 on indium tin oxide (ITO), followed by electropolymerization of o-phenylenediamine with deltamethrin as a template molecule. The template molecules were then removed from the modified electrode by a methanol. The MIP-based electrochemical sensor exhibited high sensitivity and selectivity towards deltamethrin. Under the optimized conditions, the LOD values for the MIP/Co3O4/ITO electrode in the first and second linear regressions were 1.53 nM for linear range of 2.82 nM to 56.5 nM and 0.34 μM for linear range of 0.25 μM to 3.98 μM. Moreover, the LOD values for the NIP/Co3O4/ITO electrode in the first and second regressions were 2.43 nM for the linear range of 3.91 nM to 65.0 nM and 726.0 nM for the linear range of 0.023 μM to 4.5 μM. The developed electrochromic pesticide sensor, being an electrochemical-based molecularly imprinted polymer (MIP) sensor incorporating electrochromic materials, enables both target-specific pesticide detection and visual pesticide identification based on color changes dependent on pesticide concentration. Consequently, this system is more advantageous compared to electrochemical-based MIP sensors, as it provides both qualitative and quantitative determinations. The qualitative assessment aims to enhance the ease of use of the sensor, thereby increasing the potential for it to become a commercially viable product by reducing the need for instrumental devices.

Molecular imprinting sensors based on laser-induced graphene for tigecycline sensing

A highly sensitive and selective molecular imprinting sensor based on laser-induced graphene (LIG) and gold nanoparticles (AuNPs) was fabricated for the sensing of tigecycline in food samples. The LIG electrodes were fabricated using a CO2 laser, and the optimal parameters of 8.6 W power and 10 cm/s scanning speed yielded a low sheet resistance of 18.2 ± 0.8 Ω/sq. The MIP-AuNP-LIG sensor was prepared by electropolymerization of o-phenylenediamine in the presence of tigecycline template. The sensor exhibited a wide linear range (0.01–800 nM) and a low detection limit (0.003 nM) in buffer solution. In milk and meat samples, the sensor showed good sensitivity with LODs of 0.15 nM and 0.21 nM, respectively. The sensor demonstrated excellent selectivity, reproducibility (RSD = 3.6 %), stability (90 % response after 1 month), and reusability (6 cycles, RSD = 4.2 %). The MIP-AuNP-LIG sensor offers a promising tool for monitoring tigecycline residues in complex food matrices, with advantages over other methods in terms of facile fabrication, robustness, and practicality.

Development of ratiometric molecularly imprinted electrochemical sensor based on biomass aerogel derived from UiO-66-NH2 and CNTs doped lotus root powder for the effective detection of imidacloprid

Herein, a ratiometric molecularly imprinted electrochemical sensor for imidacloprid (IMI) detection is developed. The sensor is fabricated by modifying glassy carbon electrode with anthraquinone/ZrO2-carbon nanotube-biomass derived aerogel (AQ/ZrO2-CNTs-BA) composite, followed by electropolymerization of o-phenylenediamine in the presence of IMI. The BA prepared from lotus root powder possesses large specific surface area and plentiful active sites, beneficial for the immobilization of reference probe AQ and catalytic component ZrO2. CNTs can improve the composite stability and conductivity. When IMI is present, IMI molecules are rebound and its reduction peak appears. At the same time, as the occupied imprinted sites hinder the electrochemical reaction of AQ, the reduction peak of AQ decreases. Furthermore, under the optimized conditions their peak-current ratio (IIMI/IAQ) and IMI concentration shows a good linear relationship over the range of 0.05 − 10 μM. The detection limit is ca. 0.014 μM (S/N = 3). In addition, the ratiometric electrochemical sensor has good repeatability and selectivity. It has been applied to the detection of IMI in spiked samples and the recoveries are 82.0 % − 104 %.

Development of an MIP based electrochemical sensor for TGF-β1 detection and its application in liquid biopsy.

Oral cancer is one of the most common types of cancer in Europe and its large diffusion requires, together with prevention, the development of low-cost and reliable portable platforms for its diagnosis, with features of high selectivity and sensitivity. In this study, the development and characterization of a molecularly imprinted polymer (MIP)-based electrochemical sensor for TGF-β1 detection are reported. The optimized biosensor is a potential tool for the early screening of oral cancer. A biomimetic surface has been obtained by electropolymerization of o-phenylenediamine (o-PD) on platinum electrodes, in the presence of TGF-β1 as a template molecule. MIP synthesis, template removal and TGF-β1 rebinding have been monitored by Differential Pulse Voltammetry (DPV). Atomic Force Microscopy (AFM) has been performed to investigate and characterize the surface morphology and the influence of the washing step on MIP and NIP (non-imprinted polymer as the control) while the thickness of the polymer layer has been measured by Scanning Transmission Electron Microscopy (STEM) analysis. The MIP sensor performance has been tested in both buffer solution and saliva samples with TGF-β1, showing a linear response in the considered range (from 20 ng ml-1 down to 0.5 ng ml-1), an outstanding LOD of 0.09 ng mL-1 and affinity and selectivity to TGF-β1 also in the presence of interfering molecules. The sensor was used also for the detection of target molecules in spiked saliva samples with good recovery results suggesting the possibility of the use of the proposed system for large scale fast screening in oral cancer diagnosis.

An Ascorbic Acid-Imprinted Poly(o-phenylenediamine)/AuNPs@COFTFPB-NBPDA for Electrochemical Sensing Ascorbic Acid

An electrochemical sensor based on a molecularly imprinted polymer membrane (MIP) was developed. The electrochemical sensor was prepared by electropolymerization of o-phenylenediamine (O-PD) on the surface of glassy carbon electrode (GCE), modified by AuNPs@covalent organic framework (COF) microspheres with ascorbic acid (AA) as template molecule. First, ultrasmall polyvinylpyrrolidone (PVP)-coated AuNPs were prepared by a chemical reduction method. Then, 1,3,5-tri(p-formylphenyl)benzene (TFPB) and N-boc-1,4-phenylene diamine (NBPDA) underwent an ammonaldehyde condensation reaction on PVP-coated AuNPs to form AuNPs@COFTFPB-NBPDA microspheres. The porous spherical structure of AuNPs@ COFTFPB-NBPDA could accelerate the mass transfer, enlarge the specific surface area, and enhance the catalytic activity of PVP-coated AuNPs. The electrochemical sensors, based on AuNPs@ COFTFPB-NBPDA/GCE and nMIPs/AuNPs@COFTFPB-NBPDA/GCE, were applied for the detection of AA, with a detection limit of 1.69 and 2.57 μM, as well as linear ranges of 5.07 to 60 mM and 7.81 to 60 mM. The nMIPs/AuNPs@COFTFPB-NBPDA sensor had satisfactory stability, selectivity, and reproducibility for AA detection.

Molecularly imprinted electrochemical sensor for the ultrasensitive detection of cytochrome c

Cytochrome c (Cyt c) is an important biomarker for the early stage of apoptosis that plays a role in the diagnosis and therapy of several diseases including cancer. Here, an electrochemical sensor based on molecularly imprinted polymer (MIP) for the ultrasensitive detection of Cyt c is studied. It is prepared by electropolymerization of o-phenylenediamine in the presence of Cyt c as template, followed by solvent extraction, resulting in the formation of Cyt c recognition sites. The MIP is characterised by cyclic voltammetry and differential pulse voltammetry, using ferrocenecarboxylic acid as redox probe. Voltammetric data indicates that the MIP-sensor behaves as an electrode with partially blocked surface. The partition isotherm obtained fits the Langmuir model, indicating a high affinity for Cyt c, with an association constant Ka = 5 × 10 11 M−1. DPV measurements allow to achieve extremely high analytical sensitivity and low detection limit, in the femtomolar range, with negligible unspecific adsorption. Satisfactory analytical recovery tests performed in the presence of possible interfering proteins and in diluted human serum confirmed the selectivity of the MIP-sensor as well as its potential applicability for real samples analysis.

Electrochemical detection of uric acid in undiluted human saliva using uricase paper integrated electrodes

In this study, we introduce a uricase-immobilized paper (UOx­-paper) integrated electrochemical sensor for detection of uric acid (UA) in saliva. The UOx was immobilized on the detection zone in the wax-patterned paper substrate. This UOx-paper was integrated with a Prussian blue­-modified, screen-printed carbon electrode after electropolymerization of o-phenylenediamine to construct an electrochemical cell for small-volume (20 μL) of samples. First, we optimized the fabrication conditions of UOx-paper. Next, the amperometric response of the UOx-paper-based electrochemical UA sensor was analyzed using a known concentration of UA standard solution in artificial saliva at an applied potential of − 0.1 V (versus Ag pseudo-reference electrode). The UOx-­paper based electrochemical UA sensor showed a sensitivity of 4.9 μA·mM−1 in a linear range of 50 to 1000 μM (R2 = 0.998), high selectivity and good reproducibility, as well as a limit of detection of 18.7 μM (0.31 mg/dL) UA. Finally, we quantified the UA levels in undiluted saliva samples of healthy controls (n = 20) and gout patients (n = 8). The levels were correlated with those measured with conventional salivary UA enzymatic assays as well as serum UA levels. The UOx-paper-based electrochemical UA sensor is a user-friendly and convenient tool to assess salivary UA levels.

A “signal on/off” biomimetic electrochemiluminescence sensor using titanium carbide nanodots as co-reaction accelerator for ultra-sensitive detection of ciprofloxacin

It is of great significance to explore an efficient and sensitive method for the detection of ciprofloxacin (CIP) for the protection of human health and ecological environment. In this study, a novel molecularly imprinted electrochemiluminescence sensor (MIECLS) was constructed using amino-functional titanium carbide nanodots (TNDs) as co-reactant accelerator in the cathodic electrochemiluminescence system. With K2S2O8 as co-reactant, the obvious cathode luminescence signal of carbon nitride nanosheets (CNNS) can be observed under the synergistic effect of TNDs. TNDs not only advanced the conductivity of CNNS, and the presence of amino group accelerated the reduction of the co-reactant S2O82−, which generated a rich ECL reaction intermediate SO4−• near CNNS, thus greatly enhancing the ECL signal of CNNS. In addition, the proposed MIECLS have good anti-interference, high sensitivity and selectivity by electropolymerization of o-phenylenediamine as functional monomer to form molecularly imprinted polymer (MIP) with specific recognition sites on electrode surface. The MIECLS was applied for determination of CIP, and its ECL intensity was linearly quenched with the increasing concentration of CIP from 5 × 10−9 to 5 × 10−6 mol L−1 with a detection limit of 1.20 × 10−9 mol L−1 (S/N = 3). Futhermore, in the actual sample analysis, the detection results of MIECLS showed good consistency with those of HPLC, indicating that MIECLS has a broad application prospect in the rapid and sensitive analysis of CIP in food samples.

Molecularly Imprinted Sensor for Ascorbic Acid Based on Gold Nanoparticles and Multiwalled Carbon Nanotubes

Background: L-Ascorbic acid (AA) is a kind of water soluble vitamin, which is mainly present in fruits, vegetables and biological fluids. As a low cost antioxidant and effective scavenger of free radicals, AA may help to prevent diseases such as cancer and Parkinson’s disease. Owing to its role in the biological metabolism, AA has also been utilized for the therapy of mental illness, common cold and for improving the immunity. Therefore, it is very necessary and urgent to develop a simple, rapid and selective strategy for the detection of AA in various samples. Methods: The molecularly imprinted poly(o-phenylenediamine) (PoPD) film was prepared for the analysis of L-ascorbic acid (AA) on gold nanoparticles (AuNPs) - multiwalled carbon nanotubes (MWCNTs) modified glass carbon electrode (GCE) by electropolymerization of o-phenylenediamine (oPD) and AA. Experimental parameters including pH value of running buffer and scan rates were optimized. Scanning electron microscope (SEM), fourier-transform infrared (FTIR) spectra, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were utilized for the characterization of the imprinted polymer film. Results: Under the selected experimental conditions, the DPV peak currents of AA exhibit two distinct linear responses ranging from 0.01 to 2 μmol L-1 and 2 to 100 μmol L-1 towards the concentrations of AA, and the detection limit was 2 nmol L-1 (S/N=3). Conclusion: The proposed electrochemical sensor possesses excellent selectivity for AA, along with good reproducibility and stability. The results obtained from the analysis of AA in real samples demonstrated the applicability of the proposed sensor to practical analysis.

AgNPs–PDA–GR nanocomposites-based molecularly imprinted electrochemical sensor for highly recognition of 2,4,6-trichlorophenol

A molecularly imprinted electrochemical sensor for high recognition of 2,4,6-trichlorophenol based on molecular imprinted polymers (MIPs) was successfully constructed. The sensitive and selective layer was Ag nanoparticles-polydopamine-reduced graphene oxide modified glassy carbon electrode (AgNPs-PDA-GR/GCE), which was following coupled with electro-polymerization of o-phenylenediamine (o-PD) on the surface of AgNPs-PDA-GR/GCE in the presence of 2,4,6-trichlorophenol as a template molecule. Due to the enhanced electron transfer rate of AgNPs-PDA-GR composites, the specific recognition of imprinted cavities, as well as the strong π–π stacking and hydrogen bonding between PDA-graphene and 2,4,6-TCP, MIPs/AgNPs-PDA-GR/GCE showed highly sensitive and selective recognition for 2,4,6-TCP. The electrochemical responses of imprinted sensor presents two dynamic linear relationships across the range of 2.0 ~ 10.0 nM and 10.0 ~ 100.0 nM with a detection limit of 0.7 nM. Further, the concentration of 2,4,6-TCP in water was determined by MIPs/AgNPs-PDA-GR/GCE and the recovery was about 96.4 ~ 103.3%. This study provides a new platform and design concept for the quantitative analysis of 2,4,6-TCP in real samples.

Au-Pt nanoparticles based molecularly imprinted nanosensor for electrochemical detection of the lipopeptide antibiotic drug Daptomycin

In this work, a novel electrochemical molecularly imprinted polymer (MIP) sensor for the detection of the lipopeptide antibiotic Daptomycin (DAP) is presented which integrates gold decorated platinum nanoparticles (Au-Pt NPs) into the nanocomposite film. The sensor was prepared by electropolymerization of o-phenylenediamine (o-PD) in the presence of DAP using cyclic voltammetry. Cyclic voltammetry and differential pulse voltammetry were applied to follow the changes in the MIP-layer related to rebinding and removal of the target DAP by using the redox marker [Fe(CN)6]3−/4–. Under optimized operational conditions, the MIP/Au-Pt NPs/GCE nanosensor exhibits a linear response in the range of 1-20 pM towards DAP. The limit of detection and limit of quantification were determined to be 0.161pM±0.012 and 0.489pM±0.012, respectively. The sensitivity towards the antibiotics Vancomycin and Erythromycin and the amino acids glycine and tryptophan was below 7 percent as compared with DAP. Moreover, the nanosensor was also successfully used for the detection of DAP in deproteinated human serum samples.

Voltammetric determination of adefovir dipivoxil by using a nanocomposite prepared from molecularly imprinted poly(o-phenylenediamine), multi-walled carbon nanotubes and carbon nitride.

An electrochemical sensor for adefovir dipivoxil (ADV) detection was prepared by electropolymerization of o-phenylenediamine in the presence of ADV on a glassy carbon electrode modified with multi-walled carbon nanotubes and carbon nitride. The electrode was characterized by field emission scanning electron microscopy and differential pulse voltammetry. The performance was optimized by response surface methodology. The changes in differential pulse voltammetric peak currents of the redox probe, ferricyanide, were linear to ADV concentrations in the range from 0.1 to 9.9 μmol L-1, with the detection limit of 0.05 μmol L-1 (S/N = 3). The sensor was applied to the determination of ADV in drug formulations, human serum and urine samples. It is selective due to the use of an imprinted material, well reproducible, long-term stable, and regenerable. Graphical abstract By merging the unique properties of carbon nitride with intrinsic properties of MWCNTs, and molecularly imprinted polymers, a novel electrochemical sensor with selective binding sites was prepared for determination of adefovir dipivoxil in pharmaceutical and biological samples.

Tailor-made 3D-nanoelectrode ensembles modified with molecularly imprinted poly(o-phenylenediamine) for the sensitive detection of L-arabitol

A highly selective and sensitive sensor for L-arabitol is developed combining the advantages of three-dimensional nanostructrured electrodes, namely, 3D-ensembles of gold nanowires (3DNEE), with the recognition capability of molecularly imprinted polymer (MIP). The MIP/3DNEE is prepared by controlled etching of polycarbonate templated nanoelectrode ensembles, followed by electropolymerization of o-phenylenediamine on the gold nanowires in the presence of L-arabitol as molecular imprinting template. For activating the sensor, L-arabitol is removed from the MIP with an ethanol/water mixture. The sensor is characterized by scanning electron microscopy and dispersive energy X-ray spectroscopy while its electrochemical properties are examined by cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy. Analytically usefull signals are obtained using the ferrocenylmethytrimethylammonium cation as an electroactive probe which can access the MIP cavities, furnishing voltammetric signals which scale inversely with the L-arabitol concentration. The sensor is characterized by a low detection limit (7.5 × 10−10 mol L-1), satisfactory quantification range, selectivity, reproducibility and repeatability. The applicability of the MIP/3DNEE in real samples is demonstrated by successfully quantifying L-arabitol concentration in sugarcane vinasse.

Effect of combination therapy with pcsk9 inhibitors and lipoprotein apheresis

Cytochrome c (Cyt c) is an important biomarker for the early stage of apoptosis that plays a role in the diagnosis and therapy of several diseases including cancer. Here, an electrochemical sensor based on molecularly imprinted polymer (MIP) for the ultrasensitive detection of Cyt c is studied. It is prepared by electropolymerization of o-phenylenediamine in the presence of Cyt c as template, followed by solvent extraction, resulting in the formation of Cyt c recognition sites. The MIP is characterised by cyclic voltammetry and differential pulse voltammetry, using ferrocenecarboxylic acid as redox probe. Voltammetric data indicates that the MIP-sensor behaves as an electrode with partially blocked surface. The partition isotherm obtained fits the Langmuir model, indicating a high affinity for Cyt c, with an association constant Ka = 5 × 10 11 M−1. DPV measurements allow to achieve extremely high analytical sensitivity and low detection limit, in the femtomolar range, with negligible unspecific adsorption. Satisfactory analytical recovery tests performed in the presence of possible interfering proteins and in diluted human serum confirmed the selectivity of the MIP-sensor as well as its potential applicability for real samples analysis.

Fully electrochemical MIP sensor for artemisinin

This study aims to develop a rapid, sensitive and cost-effective biomimetic electrochemical sensor for artemisinin determination in plant extracts and for pharmacokinetic studies. A novel molecularly imprinted polymer (MIP)-based electrochemical sensor was developed by electropolymerization of o-phenylenediamine (o-PD) in the presence of artemisinin on gold wire surface for sensitive detection of artemisinin. The experimental parameters, including selection of functional monomer, polymerization conditions, template extraction after polymerization, influence of pH and buffer were all optimized. Every step of imprinted film synthesis were evaluated by employing voltammetry techniques, surface-enhanced infrared absorption spectroscopy (SEIRAS) and atomic force microscopy (AFM). The specificity was further evaluated by investigating non-specific artemisinin binding on non-imprinted polymer (NIP) surfaces and an imprinting factor of 6.8 was achieved. The artemisinin imprinted polymers using o-PD as functional monomer have provided highly stable and effective binding cavities for artemisinin. Cross-reactivity studies with drug molecules showed that the MIPs are highly specific for artemisinin. The influence of matrix effect was further investigated both in artificial plant matrix and diluted human serum. The results revealed a high affinity of artemisinin-MIP with dissociation constant of 7.3 × 10−9 M and with a detection limit of 0.01 μM and 0.02 μM in buffer and plant matrix, respectively.

Electrodeposition of Both Carbon Nanotube and Glucose Oxidase on Pt Eectrode Using a Dispersed Electrolytic Solution

Immobilization of the enzyme is one of the most critical processes for the fabrication of an enzyme sensor, since it will highly influence properties of the obtained sensor. Various procedure have been proposed for a the preparation of glucose sensor, such as covalent attachment, cross-linking, hydrogel entrapment, polymer film entrapment, and the combination of two or more methods. Among the various techniques, the electrodeposition method is interesting owing to its simple preparation, miniaturization, and precise localization of enzyme. On the other hand, nanocarbons (NCs), such as carbon nanotubes (CNTs) and graphenes, are extremely attractive in biosensor application, since they can combine properties of the high surface area, high stability and good electrical conductivity. However, NCs is not soluble in aqueous solution, which is the least media to dissolve enzyme without reducing its activity. The use of surfactants is a candidate to preparer a disperse NCs in enzyme solution, while this may also reduce the enzyme activity. Therefore, processes of enzyme immobilization and NCs immobilization are commonly performed separately using different solutions. In this study, stable dispersed solutions of glucose oxidase (GOx) and multi-walled CNT were developed using gellan gum, which is a polysaccharide manufactured by microbial fermentation used widely as a gelling agents. By using this CNT/GOx dispersed solution, both CNT and GOx were successfully immobilized on Pt-Ir electrode by a simple step of applying a constant potential of 1.3 V（vs. Ag/AgCl) to the electrode in this solution. The electropolymerization of o-phenylenediamine was followed in order to increase the stability of enzyme-immobilized electrode. The CNT/GOx immobilized electrode performed as a glucose sensor with a high sensor sensitivity. This indicate that the introduction of CNT in GOx-immobilized film increased the efficiency of electron transfer between the electrode and generated hydrogen peroxide. In addition, the reproducibility of electrode fabrication was satisfactorily improved by the use of gellan gum compared with that using Triton X-100 as a dispersing agent.

Electrochemical determination of thrombin with molecularly imprinted polymers and multiwalled carbon nanotubes

The preparation and application of reagentless electrochemical thrombin molecularly imprinted sensors were studied using multiwalled carbon nanotubes as sensitivity-enhanced materials. The molecularly imprinted polymer film was prepared by the electropolymerization of o-phenylenediamine with thrombin as the template molecule onto the surface of multiwalled carbon nanotubes modified glassy carbon electrode. After removing thrombin, the poly-o-phenylenediamine molecularly imprinted film was obtained with specific recognition for thrombin. Using the poly-o-phenylenediamine molecularly imprinted polymers as the electron probe, the electrochemical molecularly imprinted sensor was fabricated for the detection of the protein thrombin. Under optimized experimental conditions, the sensor exhibited a good linear response from 10.0 fg/mL to 1.0 μg/mL for thrombin, with correlation coefficient 0.999 and a low detection limit of 1.7 fg/mL. The fabricated molecularly imprinted sensor can be applied to the detection of thrombin in actual sample bovine serum with satisfactory results.

Molecularly imprinted electrochemical sensor for daidzein recognition and detection based on poly(sodium 4-styrenesulfonate) functionalized graphene

A high sensitive and selective electrochemical sensor for detection of daidzein based on molecular imprinted polymer (MIP) modified electrode was established. The sensitive layer was prepared by electropolymerization of o-phenylenediamine (o-PD) on the surface of Poly (sodium 4-styrenesulfonate)-reduced graphene oxide (PSS-rGO) modified glassy carbon electrode (PSS-rGO/GCE) in the presence of daidzein as a template molecule. The negatively charged poly(sodium 4-styrenesulfonate) units and benzene rings of PSS-rGO can attract positive charged o-PD and provide π-π stacking effect of o-PD and daidzein, which makes the compact imprinted film and more imprinted points. The MIP/PSS-rGO composite could specifically recognize daidzein in aqueous solutions which result in the decrease of peak current of K3[Fe(CN)6]/K4[Fe(CN)6] at the MIP/PSS-rGO/GCE. Under the optimized conditions, the decrease of the peak current was linear with the concentration of daidzein in the range of 1.0-20.0nM. The detection limit was calculated as 0.5nM (S/N=3). Relative to the other structurally similar substances, the current response of the MIP/PSS-rGO/GCE toward daidzein was about 6.0, 3.1, 6.9 and 5.2 times higher than those of puerarin, quercetin, genistein and chrysin which suggesting the high selectivity of MIP/PSS-rGO/GCE. The modified electrode was successfully applied to determine daidzein in human serum and pueraria extraction with satisfied recovery suggesting the potential applications in the daidzein determination of clinical samples and nature products.

D-mannitol sensor based on molecularly imprinted polymer on electrode modified with reduced graphene oxide decorated with gold nanoparticles

An electrochemical sensor for D-mannitol based on molecularly imprinted polymer on electrode modified with reduced graphene oxide decorated with gold nanoparticles was developed in this present work. The sensor was constructed for the first time via the electropolymerization of o-phenylenediamine (o-PD) over a surface containing reduced graphene oxide (RGO) and gold nanoparticles (AuNP) in the presence of D-mannitol molecules. The surface modification with AuNP/RGO-GCE facilitated the charge transfer processes of [Fe(CN)6]3−/4−, which was used as an electrochemical probe. It also contributed meaningfully towards the increase in the surface/volume ratio, creating more locations for imprinting, and providing greater sensitivity to the sensor. The MIP/AuNP/RGO-GCE sensor was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray Photoelectron Spectroscopy (XPS). Important parameters that exert control over the performance of the molecularly imprinted sensor (such as number of cycles, pH, monomer and template concentration and extraction and rebinding conditions) were investigated and optimized. The imprinting factor was 4.9, showing greater response to the D-mannitol molecule compared to the interfering molecules. The limit of detection, limit of quantification and amperometric sensitivity were 7.7×10–13molL−1, 2.6×10–12molL−1 and 3.9×1010µALmol−1 (n=3) respectively. The MIP/AuNP/RGO-GCE sensor was successfully applied towards the selective determination of D-mannitol in sugarcane vinasse, thus making it, in essence, a valuable tool for the accurate and reliable determination of this molecule.

Ag/N-doped reduced graphene oxide incorporated with molecularly imprinted polymer: An advanced electrochemical sensing platform for salbutamol determination

In this work, the metallic silver and non-metallic nitrogen co-doped reduced graphene oxide (Ag-N-RGO) was first synthesized by a simple and cost-effective strategy, and then a molecularly imprinted polymer (MIP) was formed in situ at the surface of the prepared composite via electropolymerization of o-phenylenediamine in the presence of salbutamol as the template molecule. The electrochemical characterizations demonstrate that the bifunctional graphene-based composite shows improved catalytic performance than that of pristine graphene doped with one-component or none. The MIP sensor based on Ag-N-RGO owns high porous surface structure, resulting in the increased current response and enhanced recognition capacity than that of non-imprinted sensor. The outstanding performance of the developed sensor derives from the combined advantages of Ag-N-RGO with effective catalytic property and MIP with excellent selectivity. Under the optimal conditions, the electrochemical response of the developed sensor is linearly proportional to the concentration of salbutamol in the range of 0.03–20.00µmolL−1 with a low detection limit of 7 nmol L−1. The designed sensor has exhibited the multiple advantages such as low cost, simple manufacture, convenient use, excellent selectivity and good reproducibility. Finally, the proposed method has been extended for the determinations of salbutamol in human urine and pork samples, and the satisfactory recoveries between 98.9–105.3% are achieved.