Graphene Polyaniline Research Articles

Laser-Induced Electrochemical Biosensor Modified with Graphene-Based Ink for Label-Free Detection of Alpha-Fetoprotein and 17β-Estradiol.

In this research, a novel electrochemical biosensor is proposed based on inducing graphene formation on polyimide substrate via laser engraving. Graphene polyaniline (G-PANI) conductive ink was synthesized by planetary mixing and applied to the working zone of the developed sensor to effectively enhance the electrical signals. The laser-induced graphene (LIG) sensor was used to detect alpha-fetoprotein (AFP) and 17β-Estradiol (E2) in the phosphate buffer saline (PBS) buffer and human serum. The electrochemical performance of the biosensor in determining these biomarkers was investigated by differential pulse voltammetry (DPV) and chronoamperometry (CA). In a buffer environment, alpha-fetoprotein (AFP) and 17β-Estradiol detection range were 4-400 ng/mL and 20-400 pg/mL respectively. The experimental results showed a limit of detection (LOD) of 1.15 ng/mL and 0.96 pg/mL for AFP and estrogen, respectively, with an excellent linear range (R2 = 0.98 and 0.99). In addition, the designed sensor was able to detect these two types of biomarkers in human serum successfully. The proposed sensor exhibited excellent reproducibility, repeatability, and good stability (relative standard deviation, RSD = 0.96%, 1.12%, 2.92%, respectively). The electrochemical biosensor proposed herein is easy to prepare and can be successfully used for low-cost, rapid detection of AFP and E2. This approach provides a promising platform for clinical detection and is advantageous to healthcare applications.

Simulation performance of inkjet-printed polyaniline–graphene oxide nanocomposite based gas sensor

Simulation performance of inkjet-printed polyaniline–graphene oxide nanocomposite based gas sensor

Hydrodynamics-engineered polyaniline nanofibers on graphene nanosheets for high-performance pH sensors

Real-time sweat monitoring in the human body using wearable sensors is promising for noninvasive and continuous healthcare applications. For reliable and accurate sweat analysis, further improvement in the response time and long-term stability of sensors is required. This paper reports an electrochemical pH sensor based on polyaniline/graphene (PANi-Gr) with rapid electron and ion transfer. The implementation of the Taylor–Couette flow approach allowed the efficient exfoliation of graphite into Gr nanosheets and the rapid polymerization of aniline monomers on the Gr surface, resulting in nanofiber PANi-deposited Gr nanocomposites. PANi-Gr had a large surface area and porous structure, which are favorable for rapid and stable electrochemical reactions. The screen-printed PANi-Gr-based pH sensor exhibited a Nernstian sensitivity of 61.91 mV/pH, rapid response time of <1 s, and long-term stability upon monitoring with minimal potential drift (0.04 mV h−1) under strong acidic and basic conditions. Furthermore, the on-body performance of the wearable pH sensor integrated with a wireless electronic device was analyzed via the noninvasive real-time monitoring of human sweat pH during stationary cycling. The developed sensor can be used in wearable real-time sweat monitoring devices for medical and healthcare applications.

Enhancing precision in PANI/Gr nanocomposite design: robust machine learning models, outlier resilience, and molecular input insights for superior electrical conductivity and gas sensing performance

This study employs various machine learning algorithms to model the electrical conductivity and gas sensing responses of polyaniline/graphene (PANI/Gr) nanocomposites based on a comprehensive dataset gathered from over 100 references.

Fine-tunable ε′-negative response derived from low-frequency plasma oscillation in graphene/polyaniline metacomposites

Remarkable ε′-negative responses at radio-frequency endow metacomposites with revolutionary applications in electromagnetic (EM) fields. However, uncovering its regulation mechanism and subsequently achieving fine-tunable ε′-negative response remains challenging. Here, we meticulously designed graphene/polyaniline (GR/PANI) metacomposites above percolation, which directly enable tunable negative permittivity at an order of magnitude of −103. By rationally adjusting the three-dimensional GR network, we were able to form collective low-frequency plasma oscillation of free electrons in composites, which intrinsically contributes to the tunable ε′-negative response. Moreover, an ε′-near-zero (ENZ) response was surprisingly observed at ∼920 MHz due to the ineffectiveness of the plasmonic state at high frequencies. In addition, we carried out equivalent circuit analysis to demonstrate the phase relationship and electrical characteristics of these metacomposites. This work could contribute to a new category of polymer-matrix composites and enable exotic properties beyond their natural and bulk counterparts.

Conductive nerve conduit with piezoelectric properties for enhanced PC12 differentiation

Restoration of nerve tissue remains highly challenging, mainly due to the limited regeneration capacity of the nervous system and the development of fibrosis. This limitation necessitates designing new nerve guidance channel to promote nerve repairing. In this study, we developed a novel core/shell conduit to induce PC12 differentiation. Co-electrospinning method was utilized to produce a fibrous shell containing polycaprolactone/polyvinylidene fluoride PCL/PVDF, gelatin and polyaniline/graphene (PAG) nanocomposite. The core section of the conduit was filled with chitosan–gelatin hydrogel containing PAG and ZnO nanoparticles. Such conduit shows antibacterial activity, electrical conductivity and piezoelectric property. The effect of such engineered conduit on PC12 differentiation was investigated by analyzing differentiation markers Nestin and microtubule-associated protein 2 (MAP2) through immunocytochemistry and PCR-RT techniques. The result revealed that such conduit could significantly induce Nestin and MAP2 gene expression in the PC12 cells and, thus, it is a viable option for effective cell differentiation and nerve regeneration.

High-Performance Stretchable Supercapacitors Based on Centrifugal Electrospinning-Directed Hetero-structured Graphene–Polyaniline Hierarchical Fabric

High-Performance Stretchable Supercapacitors Based on Centrifugal Electrospinning-Directed Hetero-structured Graphene–Polyaniline Hierarchical Fabric

Polyaniline–Graphene Oxide Composites Decorated with ZrO2 Nanoparticles for Use in Screen-Printed Electrodes for Real-Time l-Tyrosine Sensing

Polyaniline–Graphene Oxide Composites Decorated with ZrO₂ Nanoparticles for Use in Screen-Printed Electrodes for Real-Time <scp>l</scp>-Tyrosine Sensing

Honeycomb graphene–polyaniline nanocomposites as novel electrode materials for high-performance supercapacitors

Honeycomb graphene–polyaniline (HG–PANI) nanocomposites are synthesized through a facile electrostatic self-assembly approach, and the obtained material is characterized as the electrode for supercapacitor applications.

Polyaniline—Graphene Electrodes Prepared by Electropolymerization for High-Performance Capacitive Electrodes: A Brief Review

Both polyaniline (PANI) and graphene are widely studied for their application as capacitive electrodes in energy storage devices. However, although PANI can be easy synthesized, is of low cost and has a higher specific capacitance than graphene, pristine PANI electrodes do not present long-term stability due to their large volume changes during release/doping of the electrolyte ions and surface area reduction with charge-discharge cycling. That is why a combination of PANI with carbonaceous materials, especially conductive and high-surface-area graphene as well as more widely used reduced graphene oxide (rGO), provides an effective approach to solve these problems. At the same time, the electropolymerization process is one of the possible methods for synthesis of PANI composites with G or rGO as freestanding electrodes. Therefore, no binders or additives such as carbon black or active carbon need to be used to obtain PANI/rGO electrodes by electrochemical polymerization (EP), in contrast to similar electrodes prepared by the chemical oxidative polymerization method. Thus, in this paper, we review recent advances in EP synthesis of PANI/rGO nanocomposites as high-performance capacitive electrode materials, combining the advantages of both electrical double-layer capacitance of rGO and pseudocapacitance of PANI, which hence exhibit long cycle life and high specific energy.

Preparation and characterization of self-stimuli conductive nerve regeneration conduit using co-electrospun nanofibers filled with gelatin-chitosan hydrogels containing polyaniline-graphene-ZnO nanoparticles

The core-shell structure conduit with conductive, antibacterial, and highly piezoelectric properties was designed and fabricated by a multi-step process. First, the shell structure was fabricated by rolling the co-electrospun mats of polycaprolactone/polyvinylidene fluoride and gelatin incorporated with polyaniline/graphene (PAG) nanocomposites. Then, the fabricated mats were filled with gelatin/chitosan hydrogels containing PAG and zinc oxide nanoparticles. Characterization of the intermediate materials and the final conduit revealed high electrical conductivity and remarkable output voltage for shell and core materials. MTT assay and antibacterial tests confirmed bioactivity and antibacterial properties of shells and cores. The results confirmed appropriateness of the conduit for nerve regeneration applications.

Laser‐Scribed Graphene–Polyaniline Microsupercapacitor for Internet‐of‐Things Applications

AbstractThe push toward smart technologies and the Internet‐of‐Things (IoT) demands the development of miniaturized energy storage devices. Herein, a facile and scalable strategy is presented, based on laser reduction of graphene oxide into graphene followed by electrodeposition of polyaniline (PANi), to fabricate a substrate‐free supercapacitor. The fabricated supercapacitor is part of a flexible multifunctional integrated system comprising a thin‐film humidity sensor, a resistor, and a near field communication (NFC) antenna for IoT‐linked wireless communication with a smartphone. The integrated sensory system shares laser‐scribed graphene (LSG) as the same electrode material for all the components (supercapacitor, sensor, resistor, and NFC antenna). The symmetric LSG‐PANi||LSG‐PANi supercapacitor with wireless charging capability exhibits a near record‐high energy density of 0.407 mW h cm−3, and excellent power density of 196 mW cm−3, along with an outstanding rate capability (enduring high rates of over 1 V s−1). As a humidity sensor, the device demonstrates high resistance changes from 2000 kΩ at 0% relative humidity (RH) to 497 kΩ at 100% RH (15 kΩ per RH%) with a sub‐second scale (0.87 s) response time. This research paves the way for limitless applications of IoT across a wide spectrum of fields from healthcare to chip‐based electronics to environmental monitoring.

Cold atmospheric plasma modification and electrical conductivity induction in gelatin/polyvinylidene fluoride nanofibers for neural tissue engineering.

This research follows some investigations through neural tissue engineering, including fabrication, surface treatment, and evaluation of novel self-stimuli conductive biocompatible and degradable nanocomposite scaffolds. Gelatin as a biobased material and polyvinylidene fluoride (PVDF) as a mechanical, electrical, and piezoelectric improvement agent were co-electrospun. In addition, polyaniline/graphene (PAG) nanoparticles were synthesized and added to gelatin solutions in different percentages to induce electrical conductivity. After obtaining optimum PAG percentage, cold atmospheric plasma (CAP) treatment was applied over the best samples by different plasma variable parameters. Finally, the biocompatibility of the scaffolds was analyzed and approved by in vitro tests using two different PC12 and C6 cell lines. In the present study the morphology, FTIR, dynamic light scattering, mechanical properties, wettability, contact angle tests, differential scanning calorimetric, rate of degradation, conductivity, biocompatibility, gene expression, DAPI staining, and cell proliferation were investigated. The PAG percentage optimization results revealed fiber diameter reduction, conductivity enhancement, young's modulus improvement, hydrophilicity devaluation, water uptake decrement, and degradability reduction in electrospun nanofibers by increasing the PAG concentration. Furthermore, ATR-FTIR, FE-SEM, AFM, and contact angle tests revealed that helium CAP treatment improves scaffold characterizations for 90s in duration time. Furthermore, the results of the MTT assay, FE-SEM, DAPI staining, and RT-PCR revealed that samples containing 2.5% w/w of PAG are the most biocompatible, and CAP treatment increases cell proliferation and improves neural gene expression in the differentiation medium. According to the results, the samples with the 2.5% w/w of PAG could provide a suitable matrix for neural tissue engineering in terms of physicochemical and biological.

Aptasensor for the Detection of Mycobacterium tuberculosis in Sputum Utilising CFP10-ESAT6 Protein as a Selective Biomarker.

A portable electrochemical aptamer-antibody based sandwich biosensor has been designed and successfully developed using an aptamer bioreceptor immobilized onto a screen-printed electrode surface for Mycobacterium tuberculosis (M. tuberculosis) detection in clinical sputum samples. In the sensing strategy, a CFP10-ESAT6 binding aptamer was immobilized onto a graphene/polyaniline (GP/PANI)-modified gold working electrode by covalent binding via glutaraldehyde linkage. Upon interaction with the CFP10-ESAT6 antigen target, the aptamer will capture the target where the nano-labelled Fe3O4/Au MNPs conjugated antibody is used to complete the sandwich format and enhance the signal produced from the aptamer–antigen interaction. Using this strategy, the detection of CFP10-ESAT6 antigen was conducted in the concentration range of 5 to 500 ng/mL. From the analysis, the detection limit was found to be 1.5 ng/mL, thereby demonstrating the efficiency of the aptamer as a bioreceptor. The specificity study was carried out using bovine serum albumin (BSA), MPT64, and human serum, and the result demonstrated good specificity that is 7% higher than the antibody–antigen interaction reported in a previous study. The fabricated aptasensor for M. tuberculosis analysis shows good reproducibility with an relative standard deviation (RSD) of 2.5%. Further analysis of M. tuberculosis in sputum samples have shown good correlation with the culture method with 100% specificity and sensitivity, thus making the aptasensor a promising candidate for M. tuberculosis detection considering its high specificity and sensitivity with clinical samples.

A simple procedure for fabricating graphene or modified graphene polyaniline composites for supercapacitor application

The depleting fuel resources and elevated air pollution are raising serious concerns among the global population. The fuel prices are also increasing day by day. Hence the world is more focused on maximizing conventional energy resources like solar, tidal, wind energies, etc. However, for the fullest utilization of conventional energy sources, we need efficient energy storage systems, and currently, we are using batteries as the primary energy storage elements. Nowadays, researchers are giving utmost importance to the development of supercapacitors. Graphene coming under carbon groups and polyaniline (PANI), coming under electronic conducting polymers (ECP), are two different materials mainly used for supercapacitor electrode fabrication. The normal route for synthesizing graphene-PANI composites is a time-consuming process. Here we present a simple route for synthesizing graphene-PANI composites. The same method can be adopted for fabricating modified graphene-PANI composites too. The FTIR, Raman spectroscopy, XRD, SEM, and TEM results showed that the formation of graphene-PANI composites in the current route is the same as that of the normal method. Moreover, the cyclic voltammetry (CV) and charge–discharge (CD) tests revealed excellent electrochemical performance and cyclability. The CV study reported that the specific capacitances of the supercapacitor are 235, 179, 120, 85, and 55 F/g at scan rates of 10, 20, 50, 100, and 200 mV/s.The capacitance retention ratio was more than 90% and the ESR was found to be 10.5 O.

A Principal Curves-Based Method for Electronic Tongue Data Analysis

Electronic tongues are a type of sensor inspired in the biological recognition system, where sensorial and instrumental techniques are used to determine flavors or substances present in the samples analyzed. The sensor arrays used in electronic tongues are generally non-specific and are designed to provide global information about the solution’s response. As a consequence, it usually becomes necessary to use data processing techniques that are capable of providing specific information from the samples under investigation. In this context, here we employed a Principal Curves based method to evaluate the experimental data obtained from an impedimetric electronic tongue used to evaluated distinct flavors enhancers of similar compostions. For the classification of concentrations, the best results were in the range of 88.02 to 91.15%, using electrode architectures E1 (Poly allylamine hydrochloride (PAH), reduced graphene oxide (rGO), polyaniline (PANI) and copper tetrasulfonated phthalocyanine (CuTsPc)) and E6 (PAH and CuTsPc). In the classification of substances, again the E1 architecture was highlighted, with 90.15% accuracy. These results shown that principal curves may be a promising technique for electronic tongues data analysis.

A high-performance covalently bonded self-doped polyaniline–graphene assembly film with superior stability for supercapacitors

In this study, a robust high-performance polyaniline-modified graphene electrode is successfully used to assemble a supercapacitor. Graphene is covalently bonded to self-doped polyaniline (SPANI) and used in supercapacitors, and 4-aminobenzoic acid-modified graphene (ABF-G) sheet materials are first bonded to an aniline functional group at graphene edges. Then, aniline, o-aminobenzene sulfonic acid monomers, and an oxidising agent are added into the ABF-G aqueous dispersion to achieve polymerisation on the surface of ABF-G. This covalently bonded SPANI-modified ABF-G (SPANI-ABF-G) thin-film electrode material is then used for fabricating supercapacitors. A Raman spectrometer, a scanning electron microscope, a secondary ion mass spectrometer, an X-ray electron photon spectrometer, and a specific surface area analyser are used to characterise this film. The supercapacitor with the proposed SPANI-ABF-G electrodes exhibits a high specific capacitance value of 642.6 F/g for charging and discharging at a current density of 1 A/g. After 5000 cycle-life testing, this supercapacitor exhibits a charging and discharging capacitance retention of 100% and 98.13% at a current density of 1 and 2 A/g, respectively. These capacitance retentions are higher than those of supercapacitors with conductive polymers electrodes. The results prove that electrode materials prepared using covalently bonded graphene and PANI can considerably improve supercapacitor performance.

Portable electrochemical immunosensor for detection of Mycobacterium tuberculosis secreted protein CFP10-ESAT6 in clinical sputum samples.

An early detection of Mycobacterium tuberculosis is very important to reduce the number of fatal cases and allow for fast recovery. However, the interpretation of the result from smear microscopy requires skilled personnel due to the propensity of the method to produce false-negative results. In this work, a portable, rapid, and simple sandwich-type immunosensor reader has been developed that is able to detect the presence of M. tuberculosis in sputum samples. By using sandwich-type immunosensor, an anti-CFP10-ESAT6 antibody was immobilized onto the graphene/polyaniline (GP/PANI)-modified gold screen-printed electrode. After incubation with the target CFP10-ESAT6 antigen, the iron/gold magnetic nanoparticles (Fe3O4/Au MNPs) conjugated with anti-CFP10-ESAT6 antibody were used to complete the sandwich format. Differential pulse voltammetry (DPV) technique was used to detect the CFP10-ESAT6 antigen at the potential range of 0.0-1.0V. The detection time isless than 2h. Under optimal condition, CFP10-ESAT6 antigen was detected in a linear range from 10 to 500ngmL-1 with a limit of detection at 1.5ngmL-1. The method developed from this process was then integrated into a portable reader. The performance of the sensor was investigated and compared with the standard methods (culture and smear microscopy). It provides a good correlation (100% sensitivity and 91.7% specificity) with both methods of detection for M. tuberculosis in sputum samples henceforth, demonstrating the potential of the device as a more practical screening tool.Graphical abstract.

Efficient nickel or copper oxides decorated graphene–polyaniline interface for application in selective methanol sensing

Graphene sheets decorated with nickel or copper oxides that were anchored on polyaniline (denoted as PANI-graphene/NiO and PANI-graphene/CuO) were prepared by a simple, easy to-control electrochemical method and applied as novel materials for sensitive and selective methanol sensing. The fabricated sensors exhibited good electrocatalytic activity, appropriate dynamic linear range (20–1300 mM), sensitivity (0.2–1.5 μA mM−1 cm−2) and excellent selectivity towards methanol. It should be highlighted from the selectivity tests that no significant interference was observed from ethanol and other alcohols. To our best knowledge, using inexpensive but efficient transition metals like Ni, Cu instead of Pt, Pd and their composites with PANI, graphene would be scientifically novel and practically feasible approach for sensor fabrication that could be potentially used to identify methanol adulteration in counterfeit alcoholic beverages.

Fabrication of polyaniline–graphene oxide hybrid nanocomposites by green interfacial polymerization for all-solid-state supercapacitors and enzymatic glucose sensors

PANI-GO hybrid nanocomposites by the green interfacial polymerization method for electrochemical capacitors and glucose sensors.