Nafion Composite Film Research Articles

Preparation of CoFe@C composite modified electrode for neohesperidin dihydrochalcone sensing and its application in Chinese medicine.

CoFe@C was first prepared by calcining the precursor of CoFe-metal-organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for anelectrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range0.08 ~ 20µmol/L, and the linear regressioncoefficient was 0.9957. The detection limit was as low as 14.2nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC).

Large-area 11.75% efficient vertical graphene nanowalls/textured silicon Schottky junction solar cell based on PEDOT:Nafion doping scheme

Preparing large areas of graphene on textured silicon is necessary for the industrialization of graphene/silicon solar cells. However, many passivation films with insulating properties prepared by the solution method are not applicable for the textured structures as the insulation areas are easily formed at the bottom of the pyramid. In this paper, we prepare large-area vertical graphene nanowalls (VGNWs) on textured c-Si by plasma-enhanced chemical vapor deposition (PECVD) and introduce conductive-passivating poly(3,4-ethylenedioxythiophene) (PEDOT):Nafion composite thin films to modify the textured VGNWs/Si Schottky junction. The formation of insulation areas was avoided. Moreover, the reflectivity was reduced to less than 7% as the superposition of textured structures and PEDOT:Nafion film. After applying an interfacial layer of Al2O3, the cell efficiency was increased to 11.75%, with a large active area of 0.64 cm2. This work will promote the industrialization of VGNWs/Si solar cells.

Energy harvesting properties of the Nafion thin films

In this report, energy harvesting properties of Nafion films were investigated using piezoionic generator (PIOG) and triboelectric generator (TEG) devices. Nafion films were prepared by simple doctor blade deposition of a Nafion ionomer solution onto the aluminum electrode. The Nafion films were characterized for their surface morphology, composition, and crystallinity. Furthermore, the Nafion film exhibited strong substrate adhesion, a smooth surface, and amorphous nature. The deposited Nafion film was used directly as an active layer to fabricate the PIOG and TEG devices with ITO electrodes. Output voltages of ∼450 mV and ∼1.9 V have been observed for the PIOG and TEG devices against biomechanical energy. The maximum instantaneous power produced by these devices is approximately ∼0.205 μW cm−2, and ∼0.128 μW cm−2 for the PIOG and TEG, respectively. The PIOG performance can be further improved using Nafion composite films. Similarly, the TEG performance can be enhanced with other friction layers such as PVDF, PDMS, PMMA, and PVC films instead of ITO. Therefore, the proposed nanogenerators can be used as touch sensors and energy sources for wearable electronic devices in the future.

A Flexible and Regenerative Aptameric Graphene–Nafion Biosensor for Cytokine Storm Biomarker Monitoring in Undiluted Biofluids toward Wearable Applications

AbstractWearable sensors that can conveniently detect cytokine levels in human biofluids are essential for assisting hospitals to maximize the benefits of anti‐inflammatory therapies and avoid cytokine storms. Measurement of cytokine levels in biofluids still remains challenging for existing sensors due to high interference from the background. Here, this challenge is overcome through developing a flexible and regenerative aptameric field‐effect transistor biosensor, consisting of a graphene–Nafion composite film, for detecting cytokine storm biomarkers in undiluted human biofluids. The composite film enables the minimization of nonspecific adsorption and empowers the renewability to the biosensor. With these capabilities, the device is capable of consistently and sensitively monitoring cytokines (e.g., IFN‐γ, an inflammatory and cancer biomarker) in undiluted human sweat with a detection range from 0.015 to 250 nm and limit of detection down to 740 fm. The biosensor is also shown to incur no visible mechanical damage and maintain a consistent sensing response throughout the regenerative (up to 80 cycles) and crumpling (up to 100 cycles) tests. Experimental results demonstrate that the biosensor is expected to offer opportunities for developing wearable biosensing systems for distinguishing acute infectious disease patients and monitoring of patients’ health conditions in daily life.

Conductive Hole‐Selective Passivating Contacts for Crystalline Silicon Solar Cells

AbstractDefect state passivation and conductivity of materials are always in opposition; thus, it is unlikely for one material to possess both excellent carrier transport and defect state passivation simultaneously. As a result, the use of partial passivation and local contact strategies are required for silicon solar cells, which leads to fabrication processes with technical complexities. Thus, one material that possesses both a good passivation and conductivity is highly desirable in silicon photovoltaic (PV) cells. In this work, a passivation‐conductivity phase‐like diagram is presented and a conductive‐passivating‐carrier‐selective contact is achieved using PEDOT:Nafion composite thin films. A power conversion efficiency of 18.8% is reported for an industrial multicrystalline silicon solar cell with a back PEDOT:Nafion contact, demonstrating a solution‐processed organic passivating contact concept. This concept has the potential advantages of omitting the use of conventional dielectric passivation materials deposited by costly high‐vacuum equipment, energy‐intensive high‐temperature processes, and complex laser opening steps. This work also contributes an effective back‐surface field scheme and a new hole‐selective contact for p‐type and n‐type silicon solar cells, respectively, both for research purposes and as a low‐cost surface engineering strategy for future Si‐based PV technologies.

Fabrication of Non-Enzymatic Sensor Utilizing Carbon Nanotubes- Nafion Film for Nanoscale Determination of Antiviral Drug

Rapid emergence of viral diseases has posed a consequential threat to all human and veterinary health. Over past two decades these diseases are major cause of death among all infectious diseases worldwide. Acyclovir (ACV) which is a synthetic purine based nucleoside analogue plays a pivotal role in the therapy of viral diseases and possesses the best safety profile of all antivirals licensed so far. ACV is an emerging drug for the clinical treatment against herpes simplex virus, hepatitis B virus, varicella zoster virus and epstein-barr virus. ACV is marketed in the form of ophthalmic ointments, dermal cream, injections, capsules and oral tablets which have been extensively and effectively used for the treatment of herpes virus infections. The drug provides remarkable therapeutic benefit in the therapy of viral diseases like cold sores, keratitis, corneal blindness, encephalitis and virally infected central nervous system. Several adverse outcomes like neurotoxicity, nephrotoxicity, urticaria, phlebophlogosis, diarrhoea, cephalalgia, emesis and swoon are associated with higher intake of ACV and its abuse. Various analytical techniques other than electrochemical have several inconveniences which include lengthy and tedious sample preparation procedures, long analysis time and need of trained technicians. Chromatographic methods suffer from consumption of large volumes of high purity organic solvents and requirement of expensive sophisticated instruments. These methods also suffer from lack of selectivity and sensitivity which makes them unsuitable for routine analysis. In recent years, much attention has been focused on the preparation of a variety of nanomaterials with highly controllable size, shape, surface charge and physicochemical characteristics. The alluring properties of nanomaterial exhibit signal amplification due to which they are prodigiously used for the fabrication of a wide range of electrochemical sensors. Single walled carbon nanotubes (SWNTs) displaying quantum dots and wires at very low temperatures enhances the electrode conductivity and facilitates the electron transfer between myriad electroactive species and the underlying electrode. Nafion which is a sulfonated tetrafluorethylene copolymer possessing pronounced antifouling capacity, chemical inertness, strong adsorption ability, thermal stability and biocompatibility renders it to be extensively employed as an electrode modifier. A simple and sensitive approach is proposed for the accurate monitoring of antiviral drug ACV utilizing glassy carbon electrode (GCE) fabricated with SWNTs and nafion composite film employing square wave voltammetry for the first time. The developed sensor exhibits effective and sustained electron mediating behavior displaying higher peak currents at lower potential than those obtained at bare GCE. The developed sensor engendered ∼2.5 fold larger electroactive surface area in comparison to bare GCE which substantially accelerated the rate of electron transfer via improved electrical conductivity. At optimal experimental conditions, oxidation current showed a wide linear response for ACV in the concentration range from 10 nM to 30 µM. The proposed sensor exhibited pronounced analytical performance for the determination of ACV with limit of detection corresponding to 1.8 nM and high sensitivity of 15.4 µA µM-1. The modified sensor showcased high recognition selectivity, fair reproducibility and long term stability of signal response in the physiological environment. The developed prototype was successfully implemented to quantify ACV in several commercially available pharmaceuticals. The versatile method described herein was efficaciously applied further in detecting ACV in real human urine sample of patient undergoing pharmacological treatment with ACV. The results explicitly demonstrate the applicability of the developed sensor in quality control, pharmacokinetic studies and clinical analysis.

Sensing Platform for Antiviral Drug in Pharmaceuticals and Human Physiology Exploiting Electrocatalytic Properties of Carbon Nanomaterials

In recent years, much attention has been focused on the preparation of a variety of nanomaterials with highly controllable size, shape, surface charge and physicochemical characteristics. The alluring properties of nanomaterial exhibit signal amplification due to which they are prodigiously used for the fabrication of a wide range of electrochemical sensors. Single walled carbon nanotubes (SWNTs) displaying quantum dots and wires at very low temperatures enhances the electrode conductivity and facilitates the electron transfer between myriad electroactive species and the underlying electrode. Nafion which is a sulfonated tetrafluorethylene copolymer possessing pronounced antifouling capacity, chemical inertness, strong adsorption ability, thermal stability and biocompatibility renders it to be extensively employed as an electrode modifier. Rapid emergence of viral diseases has posed a consequential threat to all human and veterinary health. Over past two decades these diseases are major cause of death among all infectious diseases worldwide. Acyclovir (ACV) which is a synthetic purine based nucleoside analogue plays a pivotal role in the therapy of viral diseases and possesses the best safety profile of all antivirals licensed so far. ACV is an emerging drug for the clinical treatment against herpes simplex virus, hepatitis B virus, varicella zoster virus and epstein-barr virus. ACV is marketed in the form of ophthalmic ointments, dermal cream, injections, capsules and oral tablets which have been extensively and effectively used for the treatment of herpes virus infections. The drug provides remarkable therapeutic benefit in the therapy of viral diseases like cold sores, keratitis, corneal blindness, encephalitis and virally infected central nervous system. Several adverse outcomes like neurotoxicity, nephrotoxicity, urticaria, phlebophlogosis, diarrhoea, cephalalgia, emesis and swoon are associated with higher intake of ACV and its abuse. Various analytical techniques other than electrochemical have several inconveniences which include lengthy and tedious sample preparation procedures, long analysis time and need of trained technicians. Chromatographic methods suffer from consumption of large volumes of high purity organic solvents and requirement of expensive sophisticated instruments. These methods also suffer from lack of selectivity and sensitivity which makes them unsuitable for routine analysis. A simple and sensitive approach is proposed for the accurate monitoring of antiviral drug ACV utilizing glassy carbon electrode (GCE) fabricated with SWNTs and nafion composite film employing square wave voltammetry for the first time. The developed sensor exhibits effective and sustained electron mediating behavior displaying higher peak currents at lower potential than those obtained at bare GCE. The developed sensor engendered ∼2.5 fold larger electroactive surface area in comparison to bare GCE which substantially accelerated the rate of electron transfer via improved electrical conductivity. At optimal experimental conditions, oxidation current showed a wide linear response for ACV in the concentration range from 10 nM to 30 µM. The proposed sensor exhibited pronounced analytical performance for the determination of ACV with limit of detection corresponding to 1.8 nM and high sensitivity of 15.4 µA µM-1. The modified sensor showcased high recognition selectivity, fair reproducibility and long term stability of signal response in the physiological environment. The developed prototype was successfully implemented to quantify ACV in several commercially available pharmaceuticals. The versatile method described herein was efficaciously applied further in detecting ACV in real human urine sample of patient undergoing pharmacological treatment with ACV. The results explicitly demonstrate the applicability of the developed sensor in quality control, pharmacokinetic studies and clinical analysis.

Preparation and luminescent properties of CaF2:Ln3+ (Ln:Er, Er/Yb)/Nafion composite films

In this work, CaF2:Ln3+ (Ln:Er,Er/Yb)/Nafion composite films were prepared using Nafion as modifications and matrices by dripping method. The composite films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Composite films are transparent and CaF2:Ln3+ (Ln:Er,Er/Yb) nanoparticles are well dispersed in Nafion films. The thicknesses of CaF2:Er3+/Nafion and CaF2:Er3+,Yb3+/Nafion composite film are about 77 and 73 μm, respectively. The nanoparticles in composite film possess cubic phase. CaF2:Er3+,Yb3+/Nafion composite film has stronger characteristic emission of Er3+ around 1530 nm with full width at half-maximum (FWHM) of 73 nm and longer luminescence lifetimes of 22.04 μs (25.03%) and 100.77 μs (74.97%).

Nanoscale determination of antiviral drug acyclovir engaging bifunctionality of single walled carbon nanotubes – nafion film

An elementary and exemplary approach is proposed for the accurate monitoring of antiviral drug acyclovir (ACV) utilizing glassy carbon electrode (GCE) fabricated with single-walled carbon nanotubes and nafion composite film employing square wave voltammetry for the first time. The developed sensor exhibits effective and sustained electron mediating behavior displaying higher peak currents at lower potential than those obtained at bare GCE. At optimal experimental conditions, oxidation current showed a wide linear response for ACV in the concentration range from 10 nM to 30 μM. The proposed sensor exhibited pronounced analytical performance for the determination of ACV with limit of detection corresponding to 1.8 nM and high sensitivity of 15.4 μA μM−1. The modified sensor showcased high recognition selectivity, fair reproducibility and long term stability of signal response in the physiological environment. The developed prototype was successfully implemented to quantify ACV in several commercially available pharmaceuticals. The versatile method described herein was efficaciously applied further in detecting ACV in real human urine sample of patient undergoing pharmacological treatment with ACV. The results explicitly demonstrate the applicability of the developed sensor in quality control, pharmacokinetic studies and clinical analysis.

Sensitive detection of brucine an anti-metastatic drug for hepatocellular carcinoma at carbon nanotubes – nafion composite based biosensor

A neoteric approach for the electrochemical analysis of brucine in biological environment has been developed. The glassy carbon electrode modified with single walled carbon nanotubes and nafion composite film is delineated for the first time to determine brucine employing square wave voltammetry. The quantification of brucine at physiological pH 7.2 manifests remarkable performance at the developed biosensor. The effect of several operational parameters has been studied in the present investigation. Under optimized conditions, a dynamic linear range from 1nM to 8µM with a high sensitivity of 340.8µAµM−1 and limit of detection corresponding to 0.11nM was achieved. The interfering effect of some coexisting metabolites on the current response of brucine has been reported. The method was successfully applied for the detection of brucine in traditional pharmaceutical formulations. The biological relevance of the present method has been demonstrated by the analysis of the alkaloid in human serum and urine samples. The analytical utility was further assessed by the selective determination of brucine in Strychnos nux-vomica seeds exhibiting considerable potential as a diagnostic tool.

Very sensitive electrochemical determination of diuron on glassy carbon electrode modified with reduced graphene oxide–gold nanoparticle–Nafion composite film

In this work, a very sensitive electrochemical sensor based on glassy carbon electrode (GCE) modified with reduced graphene oxide–gold nanoparticles/Nafion (rGO–AuNPs/Nafion) composite film was applied to determine diuron. Synthesized GO was characterized using X-ray diffraction (XRD) and UV–visible spectroscopy. The surface morphology of the rGO–AuNPs/Nafion film was also characterized using scanning electron microscopy and electrochemical impedance spectroscopy. Cyclic voltammetry (CV) and adsorptive differential pulse voltammetry (AdDPV) were applied to investigate the electrochemical response of the diuron on the modified electrode. The electrode showed a linear response at 1.0×10−9−1.0×10−7 M and a detection limit of 0.3nM under the optimized conditions. The effect of some other species on the determination of diuron was investigated and the sensor showed good selectivity for determination of diuron. The constructed sensor was applied to determine diuron in enriched samples of orange juice, mineral and tap water which statistical t-test showed accuracy of method. Also the sensor was applied to obtain diuron content in the tea sample. The reliability of the proposed sensor was confirmed after comparing the results with those obtained using high performance liquid chromatography (HPLC) as a comparative method.

Correlation between the proton conductivity and diffusion coefficient of sulfonic acid functionalized chitosan and Nafion composites via impedance spectroscopy measurements

Electrochemical Impedance Spectroscopy (EIS) was employed to estimate the global transverse proton diffusion coefficient, D H +, in sulfonic acid functionalized sustainable chitosan (CS-SO3H)/Nafion composite films. In contrast to conventional conductivity measurements, EIS measurements were performed at room temperature with a film/liquid interface. In this configuration, the measure of the bulk proton transport is correlated to the D H + of the membranes which is close to 1.1 × 10−6 cm2 s−1 and 0.33 × 10−6 cm2 s−1 with and without CS-SO3H, respectively. These D H + values permitted the proton conductivity (σ H +) ratio (∼3.9) between the Nafion/CS-SO3H composite and pristine Nafion films to be estimated by using the Nernst-Einstein relationship. This ratio presents a good agreement with that obtained for the σ H + of bulk membranes (∼3.2) measured at 30 °C and 90% RH. The agreement between the σ H + ratios validates our methodology for D H + estimation by EIS and suggests that the more than three times enhanced $$ {\sigma}_H^{+} $$ is governed by the ∼3 times higher D H + in the presence of CS-SO3H.

Electrochemistry and electrocatalysis of myoglobin immobilized in sulfonated graphene oxide and Nafion films

In this study, sulfonated graphene oxide (SGO) was synthesized and characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was used to make Mb–SGO–Nafion composite films by coating myoglobin (Mb) on the glassy carbon electrodes (GCE). Positions of the Soret absorption bands suggested that Mb retained its native conformation in the films. Mb–SGO–Nafion film modified electrode showed a pair of well-defined and nearly reversible cyclic voltammetry peaks at around −0.39 V versus saturated calomel electrode (SCE) in pH 7.0 buffers, characteristic of heme Fe(III)/Fe(II) redox couples. Electrochemical parameters such as electron transfer rate constant (ks) and formal potential (Eo′) were estimated by fitting the data of square-wave voltammetry with nonlinear regression analysis. Experimental data demonstrated that the electron transfer between Mb and electrode was greatly facilitated and showed good electrocatalytic properties toward various substrates, such as H2O2 and NaNO2, with significant lowering of reduction overpotential.

Electrochemiluminescent detection of methamphetamine and amphetamine

Direct detection of amphetamine type stimulants (ATSs) including methylamphetamine (MA) in street samples and biological matrices without the need for pretreatment or extraction is a great challenge for forensic drug analysis. Electrochemical techniques, such as electrochemiluminescence (ECL), are promising tools for this area of analysis. This contribution focuses on the electrochemical and photochemical properties of [Ru(bpy)3]2+ Nafion composite films and their subsequent use for the detection of ATS in particular MA. Under optimised conditions, the response linearly increased with the concentration over the concentration range 50pM≤[MA]≤1mM while an equivalent dynamic range was obtained for amphetamine with a correlation coefficient of 0.9903 and 0.9948 respectively. The ECL signal was monitored at ∼620nm, representing the λmax for the [Ru(bpy)3]2+ Nafion composite films. This wavelength is shifted by approximately 15nm compared to the photoexcited λmax for the same system. The modified films were formed by direct interaction with the electrode surface without the need for surface modification or chain linkers. This is a major advantage for the fabrication of any sensor as it reduces the synthesis times resulting in more economically and cheaper production costs. This technique is simple, rapid, selective and sensitive, and shows potential for the high-throughput quantitation of ATS as well as possibilities for adaptation with other techniques such as FIA or LC systems.

Voltammetry and Flow Injection Analysis with Amperometric Detection for Sensitive Sodium Metamizole Determination on Glassy Carbon Electrode Modified with SWCNTs/Nafion

Novel, rapid and high sensitive voltametric methods and flow injection analysis were proposed for the determination of sodium metamizole on glassy carbon electrode modified with single-walled carbon nanotube with Nafion composite film. The results showed that SWCNT/Nafion remarkably enhanced the oxidation of metamizole which improved the anodic peak current of metamizole significantly. Under the optimized conditions peak current was proportional to sodium metamizole concentration in the range from 0.15 to 5 μM (DPV method) and from 20 to 100 μM (FIA method). The detection limit was 13 nM for DPV and 0.4 μM for FIA determination. The RSD for proposed methods were equal to 4.1% (n = 9) and 2.4% (n = 7) for voltammetry and FIA measurement respectively. Proposed methods were successfully validated by studying the recovery of metamizole in drugs and urine.

Electrochemiluminescence sensor for melamine based on a [formula omitted]-doped silica nanoparticles/carboxylic acid functionalized multi-walled carbon nanotubes/Nafion composite film modified electrode

In this work, a sensitive electrochemiluminescence (ECL) sensor for the determination of melamine (MEL) was developed based on a Ru(bpy)32+-doped silica nanoparticles (RUDS)/carboxylic acid functionalized multi-walled carbon nanotubes (CMWCNTs)/Nafion composite film modified electrode. The homogeneous spherical RUDS were synthesized by a reverse microemulsion method. As Ru(bpy)32+ were encapsulated in the RUDS, Ru(bpy)32+ dropping from the modified electrode can be greatly prevented, which is helpful for obtaining a stable ECL signal. Moreover, to improve the conductivity of the film and promote the electron transfer rate on electrode surface, CMWCNTs with excellent electrical conductivity and large surface area were applied in the construction of the sensing film. As CMWCNTs acted as electron bridges making more Ru(bpy)32+ participate in the reaction, the ECL intensity was greatly enhanced. Under the optimum conditions, the relative ECL signal (△IECL) was proportional to the logarithmic MEL concentration ranging from 5×10−13 to 1×10−7molL−1 with a detection limit of 1×10−13molL−1. To verify the reliability, the thus-fabricated ECL sensor was applied to determine the concentration of MEL in milk. Based on these investigations, the proposed ECL sensor exhibited good feasibility and high sensitivity for the determination of MEL, promising the applicability of this sensor in practical analysis.

Fabrication of metal-organic single crystalline nanowires and reduced graphene oxide enhancement for an ultrasensitive electrochemical biosensor.

A novel strategy is first presented here to design and construct a good selective and highly sensitive dopamine (DA) biosensor based on single-crystalline CuPc nanowires with a reduced graphene oxide-Nafion film (rGON/CuPcNWs). Metal-organic semiconductor single-crystalline CuPc nanowires with excellent electronic properties and large surface-to-volume ratios were prepared using a physical vapor transport technique and modified onto a glassy carbon electrode (GCE), and exhibited high electrocatalytic activity for DA detection by immobilizing it onto a GCE with a film of the rGON composite. The introduction of a rGO-Nafion film can significantly improve the electrochemical signal of the CuPcNWs. The relevant detection limit toward dopamine is 0.3 nM with a wide linear range from 0.001 μM to 200 μM. The results of the demonstrated biosensor could provide important enlightenment for the design of more sensitive electrochemical biosensors.

Highly Sensitive Electrochemical Sensor for the Determination of 8-Hydroxy-2′-deoxyguanosine Incorporating SWCNTs-Nafion Composite Film

8-Hydroxy-2′-deoxyguanosine (8-OHdG) is a typical biomarker of oxidative DNA damage and has attracted much attention in recent years since the level of 8-OHdG in body fluids is typically associated with various diseases. In this work, a simple and highly sensitive electrochemical sensor for the determination of 8-OHdG was fabricated incorporating single wall carbon nanotubes- (SWCNTs-) Nafion composite film coated on glassy carbon electrode. Nafion was chosen as an optimal adhesive agent from a series of adhesive agents and acted as a binder, enrichment, and exclusion film. Due to the strong cation-exchange ability of Nafion and the outstanding electronic properties of SWCNTs, the prepared SWCNTs-Nafion film can strongly enhance the electrochemical response to oxidation of 8-OHdG and efficiently alleviate the interferences from uric acid and ascorbic acid. The oxidation peak currents are linear with the concentration of 8-OHdG in the range of 0.03 to 1.25 μM with a detection limit of 8.0 nM (S/N = 3). This work demonstrates that SWCNTs-Nafion film can improve the sensitivity, selectivity, reproducibility, and stability, making it an ideal candidate for electrochemical detection of 8-OHdG.

Sensitive voltammetric detection of caffeine in tea and other beverages based on a DNA-functionalized single-walled carbon nanotube modified glassy carbon electrode

An electrochemical sensor, based on a DNA-functionalized single-walled carbon nanotube (DNA-SWCNT) and Nafion composite film modified GCE, was developed and used for detection of caffeine.

Square-wave stripping voltammetric determination of caffeic acid on electrochemically reduced graphene oxide–Nafion composite film

An electrochemical sensor composed of Nafion–graphene nanocomposite film for the voltammetric determination of caffeic acid (CA) was studied. A Nafion graphene oxide-modified glassy carbon electrode was fabricated by a simple drop-casting method and then graphene oxide was electrochemically reduced over the glassy carbon electrode. The electrochemical analysis method was based on the adsorption of caffeic acid on Nafion/ER-GO/GCE and then the oxidation of CA during the stripping step. The resulting electrode showed an excellent electrocatalytical response to the oxidation of caffeic acid (CA). The electrochemistry of caffeic acid on Nafion/ER-GO modified glassy carbon electrodes (GCEs) were studied by cyclic voltammetry and square-wave adsorption stripping voltammetry (SW-AdSV). At optimized test conditions, the calibration curve for CA showed two linear segments: the first linear segment increased from 0.1 to 1.5 and second linear segment increased up to 10µM. The detection limit was determined as 9.1×10−8molL−1 using SW-AdSV. Finally, the proposed method was successfully used to determine CA in white wine samples.