Iontophoretically controlled insulin delivery via water-soluble conductive polymer PANI:PSS and thermoplastic polyurethane matrix

Transdermal insulin delivery is an alternative route to deliver insulin through the body skin with the challenges to overcome the low drug skin permeability and high molecular weight. Polyaniline doped with poly(4-styrenesulfonic acid) (PANI:PSS), a conductive polymer with the high electrical conductivity, was synthesized and utilized as a drug carrier to improve the drug delivery capability from a porous thermoplastic polyurethane (TPU) matrix. The insulin was electrostatically attached to PANI:PSS based on the ion exchange between insulin and PSS. For the in vitro drug release of insulin loaded PANI:PSS relative to the pristine insulin alone, the amount of insulin released was improved to 84.70% with the time to equilibrium of 2 h under the electrical field of 6 V. For the ex vivo release-skin permeation, the amount insulin released and permeated became lower at 57.02% with time to equilibrium of 2 h, due to the pig skin acting as a barrier for insulin permeation. The modified insulin transdermal delivery, with PANI:PSS as the drug carrier and drug enhancer relative to without, is shown here to influence the insulin release rate, amount, and duration, suitable to treat diabetes patients.

Boron and nitrogen co-doped carbon nanospheres for supercapacitor electrode with excellent specific capacitance

At present, carbon materials derived from biomass precursors have many limitations in the field of energy storage. In this study, boron and nitrogen (B/N) co-doped carbon nanospheres are successfully prepared by emulsion crosslinking method using chitosan and boric acid as raw materials. After carbonization at high temperature, the carbon nanospheres can be facilely prepared with controllable particle size, showing excellent structural stability and sphericity. In addition, the heteroatoms co-doping endows the carbon nanospheres with large specific surface area, high graphitization degree and excellent electrochemical performance. Applying the carbon nanospheres for supercapacitors, the specific capacitance can reach up to 336.7 F g^-1at a current density of 1 A g^-1. Even after 10,000 cycles, the Coulomb efficiency and specific capacitance still remain at 98.61% and 96.8%, respectively, demonstrating the great promise of B/N co-doped carbon nanospheres for the state-of-the-art supercapacitor electrodes applications.

A Flexible and Transparent Zinc-Nanofiber Network Electrode for Wearable Electrochromic, Rechargeable Zn-Ion Battery

The flexible electrochromic Zn-ion battery (FE-ZiB), a newly born energy-storage technology having both electrochromic characteristics and energy-storage capability in a single device, will be a promising technology for the future transparent wearable electronics. However, the current technology limits the fabrication of FE-ZIB because the zinc (Zn) anode material is opaque and rigid. The development of a flexible and transparent Zn anode is the key factor to overcoming the current limitation. Here, for the first time, a flexible, transparent zinc-nanofiber network anode electrode (Zn@Ni@AgNFs) is reported for an FE-ZiB device that yields a remarkable electrochemical performance of a high areal capacity of 174.82 mA h m² at 0.013 mA cm^-2 applied current density, high optical contrast (50%), and excellent mechanical flexibility. The fabricated FE-ZiB device also exhibits a high volumetric energy density of 378.8 W h m^-3 at a power density of 562.7 W m^-3 . Besides, the FE-ZiB demonstrates excellent electrochromic capability with a reversible color transition from a transparent in a discharged state (0.3 V) to a dark bluish-violet in a charged state (1.6 V). These results highlight a new pathway for the development of transparent batteries for smart wearable electronic devices.

Boosting the Electrochemical Performance of Polyaniline by One-Step Electrochemical Deposition on Nickel Foam for High-Performance Asymmetric Supercapacitor

Energy generation can be clean and sustainable if it is dependent on renewable resources and it can be prominently utilized if stored efficiently. Recently, biomass-derived carbon and polymers have been focused on developing less hazardous eco-friendly electrodes for energy storage devices. We have focused on boosting the supercapacitor's energy storage ability by engineering efficient electrodes in this context. The well-known conductive polymer, polyaniline (PANI), deposited on nickel foam (NF) is used as a positive electrode, while the activated carbon derived from jute sticks (JAC) deposited on NF is used as a negative electrode. The asymmetric supercapacitor (ASC) is fabricated for the electrochemical studies and found that the device has exhibited an energy density of 24 µWh/cm² at a power density of 3571 µW/cm². Furthermore, the ASC PANI/NF//KOH//JAC/NF has exhibited good stability with ~86% capacitance retention even after 1000 cycles. Thus, the enhanced electrochemical performances of ASC are congregated by depositing PANI on NF that boosts the electrode's conductivity. Such deposition patterns are assured by faster ions diffusion, higher surface area, and ample electroactive sites for better electrolyte interaction. Besides advancing technology, such work also encourages sustainability.

Exploring the Functional Properties of Sodium Phytate Doped Polyaniline Nanofibers Modified FTO Electrodes for High-Performance Binder Free Symmetric Supercapacitors

The performance of high-rate supercapacitors requires fine morphological and electrical properties of the electrode. Polyaniline (PANI), as one of the most promising materials for energy storage, shows different behaviour on different substrates. The present study reports on the surface modification of fluorine doped tin oxide (FTO) with the sodium phytate doped PANI without any binder and its utilization as a novel current collector in symmetric supercapacitor devices. The electrochemical behaviour of the sodium phytate doped PANI thin film with and without a binder on fluorine doped tin oxide (FTO) as current collector was investigated by cyclic voltammetry (CV). The electrode without a binder showed higher electrocatalytic efficiency. A symmetrical cell configuration was therefore constructed with the binder-free electrodes. The device showed excellent electrochemical performance with high specific capacities of 550 Fg⁻¹ at 1 Ag⁻¹ and 355 Fg⁻¹ at 40 Ag⁻¹ calculated from galvanostatic discharge curves. The low charge transfer and solution resistances (R_CT and R_S) of 7.86 Ωcm² and 3.58 × 10⁻¹ Ωcm², respectively, and superior rate capability of 66.9% over a wide current density range of 1 Ag⁻¹ to 40 Ag⁻¹ and excellent cycling stability with 90% of the original capacity over 1000 charge/discharge cycles at 40 Ag⁻¹, indicated it to be an efficient energy storage device. Moreover, the gravimetric energy and power density of the supercapacitor was remarkably high, providing 73.8 Whkg⁻¹ at 500 Wkg⁻¹, respectively. The gravimetric energy density remained stable as the power density increased. It even reached up to 49.4 Whkg⁻¹ at a power density of up to 20 Wkg⁻¹.

Kinetic properties of sodium-ion transfer at the interface between graphitic materials and organic electrolyte solutions

Graphitic materials cannot be applied for the negative electrode of sodium-ion battery because the reversible capacities of graphite are anomalously small. To promote electrochemical sodium-ion intercalation into graphitic materials, the interfacial sodium-ion transfer reaction at the interface between graphitized carbon nanosphere (GCNS) electrode and organic electrolyte solutions was investigated. The interfacial lithium-ion transfer reaction was also evaluated for the comparison to the sodium-ion transfer. From the cyclic voltammograms, both lithium-ion and sodium-ion can reversibly intercalate into/from GCNS in all of the electrolytes used here. In the Nyquist plots, the semi-circles at the high frequency region derived from the Solid Electrolyte Interphase (SEI) resistance and the semi-circles at the middle frequency region owing to the charge-transfer resistance appeared. The activation energies of both lithium-ion and sodium-ion transfer resistances were measured. The values of activation energies of the interfacial lithium-ion transfer suggested that the interfacial lithium-ion transfer was influenced by the interaction between lithium-ion and solvents, anions or SEI. The activation energies of the interfacial sodium-ion transfer were larger than the expected values of interfacial sodium-ion transfer based on the week Lewis acidity of sodium-ion. In addition, the activation energies of interfacial sodium-ion transfer in dilute FEC-based electrolytes were smaller than those in concentrated electrolytes. The activation energies of the interfacial lithium/sodium-ion transfer of CNS-1100 in FEC-based electrolyte solutions were almost the same as those of CNS-2900, indicating that the mechanism of interfacial charge-transfer reaction seemed to be the same for highly graphitized materials and low-graphitized materials each other.

Graphic abstract

Hydrothermally Assisted Synthesis of Porous Polyaniline@Carbon Nanotubes-Manganese Dioxide Ternary Composite for Potential Application in Supercapattery

In this study, ternary composites of polyaniline (PANI) with manganese dioxide (MnO₂) nanorods and carbon nanotubes (CNTs) were prepared by employing a hydrothermal methodology and in-situ oxidative polymerization of aniline. The morphological analysis by scanning electron microscopy showed that the MnO₂ possessed nanorod like structures in its pristine form, while in the ternary PANI@CNT/MnO₂ composite, coating of PANI over CNT/MnO₂, rods/tubes were evidently seen. The structural analysis by X-ray diffraction and X-ray photoelectron spectroscopy showed peaks corresponding to MnO₂, PANI and CNT, which suggested efficacy of the synthesis methodology. The electrochemical performance in contrast to individual components revealed the enhanced performance of PANI@CNT/MnO₂ composite due to the synergistic/additional effect of PANI, CNT and MnO₂ compared to pure MnO₂, PANI and PANI@CNT. The PANI@CNT/MnO₂ ternary composite exhibited an excellent specific capacity of 143.26 C g^-1 at a scan rate of 3 mV s^-1. The cyclic stability of the supercapattery (PANI@CNT/MnO₂/activated carbon)-consisting of a battery type electrode-demonstrated a gradual increase in specific capacity with continuous charge-discharge over ~1000 cycles and showed a cyclic stability of 119% compared to its initial value after 3500 cycles.

Carboxymethyl Cellulose (CMC) as a Template for Laccase-Assisted Oxidation of Aniline

Polyaniline (PANi) is a conducting polymer which has been subject of intensive research on the exploitation of new products and applications. The main aim of the work is the development of a conductive bacterial cellulose (BC)-based material by enzymatic-assisted polymerization of aniline. For this, we study the role of carboxymethyl cellulose (CMC) as a template for the in situ polymerization of aniline. Bacterial cellulose was used as the supporting material for the entrapment of CMC and for the in situ oxidation reactions. The amount of CMC entrapped inside BC was optimized as well as the conditions for laccase-assisted oxidation of aniline. The new oligomers were evaluated by spectrometric techniques, namely 1H NMR and MALDI-TOF, and the functionalized BC surfaces were analyzed by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and reflectance spectrophotometry. The conductivity of the developed materials was evaluated using the four-probe methodology. The oligomers obtained after reaction in the presence of CMC as template display a similar structure as when the reaction is conducted only in BC. Though, after oxidation in the presence of this template, the amount of oligomers entrapped inside BC/CMC is considerably higher conferring to the material greater electrical conductivity and coloration. The use of CMC as a template for aniline oxidation on BC seems to be a promising and cheap strategy to improve the yield of functionalization and increment the properties of the materials, namely electrical conductivity and coloration.

Progress in Conductive Polyaniline-Based Nanocomposites for Biomedical Applications: A Review

Inherently conducting polymers (ICPs) are a specific category of synthetic polymers with distinctive electro-optic properties, which involve conjugated chains with alternating single and double bonds. Polyaniline (PANI), as one of the most well-known ICPs, has outstanding potential applications in biomedicine because of its high electrical conductivity and biocompatibility caused by its hydrophilic nature, low-toxicity, good environmental stability, and nanostructured morphology. Some of the limitations in the use of PANI, such as its low processability and degradability, can be overcome by the preparation of its blends and nanocomposites with various (bio)polymers and nanomaterials, respectively. This review describes the state-of-the-art of biological activities and applications of conductive PANI-based nanocomposites in the biomedical fields, such as antimicrobial therapy, drug delivery, biosensors, nerve regeneration, and tissue engineering. The latest progresses in the biomedical applications of PANI-based nanocomposites are reviewed to provide a background for future research.

Facile Synthesis of Nitrogen-Doped Microporous Carbon Spheres for High Performance Symmetric Supercapacitors

Nitrogen-doped microporous carbon spheres (NMCSs) are successfully prepared via carbonization and KOH activation of phenol-formaldehyde resin polymer spheres synthesized by a facile and time-saving one-step hydrothermal strategy using triblock copolymer Pluronic F108 as a soft template under the Stöber-like method condition. The influence of the ethanol/water volume ratios and carbonation temperatures on the morphologies, pore structures and electrochemical performances of the prepared NMCSs are investigated systematically. The optimal NMCSs have a large specific surface area of 1517 m2 g- 1 with a pore volume of 0.8 cm3 g- 1. The X-ray photo-electron spectroscopy analysis reveals a suitable nitrogen-doped content of 2.6 at.%. The as-prepared NMCSs used as supercapacitor electrode materials exhibit an outstanding specific capacitance of 416 F g- 1 at a current density of 0.2 A g- 1, also it shows an excellent charge/discharge cycling stability with 96.9% capacitance retention after 10,000 cycles. The constructed symmetric supercapacitors using PVA/KOH as the gel electrolyte can deliver a specific capacitance of 60.6 F g- 1 at current density of 1 A g- 1. A maximum energy density of 21.5 Wh kg- 1 can be achieved at a power density of 800 W kg- 1, and the energy density still maintains 13.3 Wh kg- 1 even at a high power density of 16 kW kg- 1. The results suggest that this work can open up a facile and effective way to synthesize the NMCSs for electrode materials of high performance energy storage devices.

High-performance asymmetric supercapacitor based on hierarchical nanocomposites of polyaniline nanoarrays on graphene oxide and its derived N-doped carbon nanoarrays grown on graphene sheets

Activated carbon (AC), as a material for asymmetric supercapacitor (ASC), is the most widely used as negative electrode. However, AC has some electrode kinetic problems which are corresponded to inner-pore ion transport that restrict the maximum specific energy and power that can be attained in an energy storage system. Therefore, it is an important topic for researchers to extend the carbonaceous material with qualified structure for negative electrode supercapacitor. In this work, novel promoted ASC have been fabricated using nanoarrays of polyaniline grown on graphene oxide sheets (PANI-GO) as positive electrode and also, carbonized nitrogen-doped carbon nanoarrays grown on the surface of graphene (CPANI-G) as negative electrode. The porous structure of the as-synthesized CPANI-G can enlarge the specific surface area and progress ion transport into the interior of the electrode materials. From the other point of view, nitrogen doping can impressively improve the wettability of the carbon surface in the electrolyte and upgrade the specific capacitance by a pseudocapacitive effect. Because of the high specific capacitance and distinguished rate performance of PANI-GO and CPANI-G and moreover, the synergistic effects of the two electrodes with the optimum potential window, the ASC display excellent electrochemical performances. In comparison with the symmetric cell based on PANI-GO (40 Wh kg^-1), the fabricated PANI-GO//CPANI-G ASC exhibits a remarkably enhanced maximum energy density of 52 Wh kg^-1. Furthermore, ASC electrode exhibits excellent cycling durability, with 90.3% specific capacitance preserving even after 5000 cycles. These admirable results show great possibilities in developing energy storage devices with high energy and power densities for practical applications.

A voltammetric biosensor based on poly(o-methoxyaniline)-gold nanocomposite modified electrode for the simultaneous determination of dopamine and folic acid

Dopamine (DA) and Folic acid (FA) are co-existing compounds in biological fluids that plays a vital role in central nervous system and human metabolism. DA is an important neurotransmitter in the brain's neural circuits and its diminution often results in Parkinson's disease. Folate is another form of folic acid, which is known as one of the B vitamins. It is utilized as an additive by women during pregnancy in order to prevent the neural tube defects. The present study reports on the fabrication of electrochemical sensor for the simultaneous determination of DA and FA using poly(o-methoxyaniline)-gold (POMA-Au) nanocomposite. The POMA-Au nanocomposite was prepared via insitu chemical oxidative polymerization method and characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The suitability of POMA-Au nanocomposite as a modifier for the electrocatalytic detection of DA and FA in aqueous solution was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CA) techniques. The fabricated POMA-Au/GCE sensor exhibited sharp and intense peaks towards the electro-oxidation of DA and FA as compared to bare electrode. The sensor exhibited the promising electron mediating behavior with well separated oxidation peaks with a potential difference of about 350.0 mV. The linear calibration plots of DA and FA were obtained from 10.0 to 300.0 μM and 0.5 to 900.0 μM with the detection limits of 0.062 μM and 0.090 μM, respectively. The reliability of this sensor was verified to be precise as well as sensitive for the determination of DA and FA in pharmaceutical samples and human urine samples.

A strategy to promote the electroactive platform adopting poly(o-anisidine)-silver nanocomposites probed for the voltammetric detection of NADH and dopamine

A study on the voltammetric detection of NADH (β-nicotinamide adenine dinucleotide), Dopamine (DA) and their simultaneous determination is presented in this work. The electrochemical sensor was fabricated with the hybrid nanocomposites of poly(o-anisidine) and silver nanoparticles prepared by simple and cost-effective insitu chemical oxidative polymerization technique. The nanocomposites were synthesized with different (w/w) ratios of o-anisidine and silver by increasing the amount of o-anisidine in each, by keeping silver at a fixed quantity. The XRD patterns revealed the semi-crystalline nature of poly(o-anisidine) and the face centered cubic structure of silver. The presence of silver in its metallic state and the formation of nanocomposite were established by XPS analysis. Raman studies suggested the presence of site-selective interaction between poly(o-anisidine) and silver. HRTEM studies revealed the formation of polymer matrix type nanocomposite with the embedment of silver nanoparticles. The sensing performance of the materials were studied via cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques. Fabricated sensor with 3:1 (w/w) ratio of poly(o-anisidine) and silver exhibited good catalytic activity towards the detection of NADH and DA in terms of potential and current response, when compared to others. Several important electrochemical parameters regulating the performance of the sensor have been evaluated. Under the optimum condition, differential pulse voltammetry method exhibited the linear response in the range of 0.03 to 900μM and 5 to 270μM with a low detection limit of 0.006μM and 0.052μM for NADH and DA, respectively. The modified electrodes exhibited good sensitivity, stability, reproducibility and selectivity with well-separated oxidation peaks for NADH and DA in the simultaneous determination of their binary mixture. The analytical performance of the nanocomposite as an electrochemical sensor was also established for the determination of NADH in human urine and water samples and DA in pharmaceutical dopamine injections with satisfactory coverage.

Sponge integrated highly compressible all-solid-state supercapacitor with superior performance

The capacitance and compressibility of the as-fabricated integrated compressible all-solid-state supercapacitor are well maintained after repeated compressing-releasing.

Polyaniline-based carbon nanospheres and redox mediator doped robust gel films lead to high performance foldable solid-state supercapacitors

As-fabricated foldable solid-state supercapacitors are suitable for highly fold-tolerant high-energy-density energy storage device applications.

Heteroatom-Doped Carbon Nanostructures Derived from Conjugated Polymers for Energy Applications

Heteroatom-doped carbon materials have been one of the most remarkable families of materials with promising applications in fuel cells, supercapacitors, and batteries. Among them, conjugated polymer (CP)-derived heteroatom-doped carbon materials exhibit remarkable electrochemical performances because the heteroatoms can be preserved at a relatively high content and keep stable under harsh working conditions. In this review, we summarized recent advances in the rational design and various applications of CP-derived heteroatom-doped carbon materials, including polyaniline (PANI), polypyrrole (PPy), and their ramification-derived carbons, as well as transition metal-carbon nanocomposites. The key point of considering CP-derived heteroatom-doped carbon materials as important candidates of electrode materials is that CPs contain only nonmetallic elements and some key heteroatoms in their backbones which provide great chances for the synthesis of metal-free heteroatom-doped carbon nanostructures. The presented examples in this review will provide new insights in designing and optimizing heteroatom-doped carbon materials for the development of anode and cathode materials for electrochemical device applications.

Colloidal and micro-carbon spheres derived from low-temperature polymerization reactions

Carbon spheres (CSs) have recently attracted major interest due to their new applications, mainly in energy storage and conversion but also in hard-templating, sorption/catalysis processes, and drug delivery systems. This is attributable to their physico-chemical properties, including their tunable morphology (solid, hollow and core-shell), size, surface area/porosity, good electrical conductivity, low external surface-to-volume ratio, high packing density, enhanced mass transport, robust mechanical stability, low cytotoxicity, and excellent biocompatibility. They can be obtained from a wide variety of carbon precursors and methods. This review covers their production by carbonization of polymer spheres from low-temperature polymerization reactions, considered here as below 250°C. This is a very important method because it allows the synthesis of CSs with different morphologies and doped with other elements or chemical compounds. The preparation of polymer spheres by this technique is well documented in the literature, and the objective of this review is to summarize and give an overview of the most significant publications, proposing a novel classification based on the formation mechanism of the polymer spheres. This classification includes the following polymerization processes: emulsion polymerization and its derivatives, seeded emulsion and inverse emulsion polymerization; precipitation polymerization and its derivative, dispersion polymerization; hard-templating; spray-drying; and hydrothermal or solvothermal treatment of carbohydrates and biomass in general. This review also reports on the morphology and surface characteristics of the CSs obtained by different synthetic approaches. The final section of the review describes the current applications of these CSs, notably in energy storage (supercapacitors and rechargeable batteries) and energy conversion (fuel cells and dye-sensitized solar cells). Besides the numerous applications listed above, they are utilized as sacrificial hard templates to prepare single- and multi-shell hollow spheres of metal oxides and other inorganic compounds and filters, as well as in adsorption and catalysis processes, drug delivery systems, and other minority applications (e.g., lubricants, black pigment in e-papers, and microwave absorber).

Ultrahigh specific surface area porous carbon nanospheres and its composite with polyaniline: preparation and application for supercapacitors

Porous carbon nanospheres (PCNSs) with an ultrahigh specific surface were prepared by carbonizing polypyrrole nanospheres and subsequent active treatment. Hierarchical composite (PCNSs/PANI) were further synthesized via in situ polymerization.

Nitrogen-doped heterostructure carbon functionalized by electroactive organic molecules for asymmetric supercapacitors with high energy density

The organic molecules (TCBQ, AQ) with multi-electron redox center are selected to modify nitrogen-doped heterostructure carbon (NHC) by noncovalent interaction and the electrode materials show good performances and potential self-matching behaviors.