Search Results (51)

In this study, electrically conductive polymer composites based on repellent N,N-diethyl-3-methylbenzamide with concentrations ranging from 6 to 30 wt% were developed. The electrical resistivity of repellent composites, as determined by electrochemical impedance spectra, ranges from 150 to 171 Ohm, which allows such materials to be used when a low voltage is applied. The study of the rheological properties of the obtained repellent composites and the analysis of the TGA curves demonstrated that the dynamic viscosity of the materials has a significant effect on the thermal diffusion of the repellent. The study of the thermal diffusion of N,N-diethyl-3-methylbenzamide demonstrated that a higher yield of repellent (up to 36.4 × 10⁻⁸ mol) is achieved when the material is applied in the form with the shortest conductor length of 14 mm. The graphs showing the relationship between the electrical flux and the concentration of N,N-diethyl-3-methylbenzamide, which was calculated via the Peltier and Thompson equations, show that, according to Onsager’s theory, the total flux of the substance is highest when a voltage is applied to the material with the shortest conductor length. Thus, the developed repellent composite is a promising material for protection against blood-sucking insects. Full article

Multifunctional polymer composites containing micro/nano hybrid reinforcements have attracted intensive attention in the field of materials science and engineering. This paper develops a multi-phase analytical model for investigating the effective electrical conductivity of micro-silicon carbide (SiC) whisker/nano-carbon black (CB) polymer composites. First, CB nanoparticles are dispersed within the non-conducting epoxy to achieve a conductive CB-filled nanocomposite and its electrical conductivity is predicted. Some critical microstructures such as volume percentage and size of nanoparticles, and interphase characteristics surrounding the CB are micromechanically captured. Next, the electrical conductivity of randomly oriented SiC-containing composites in which the nanocomposite and whisker are considered as the matrix and reinforcement phases, respectively, is estimated. Influences of whisker aspect ratio and volume fraction on the effective electrical conductivity of the SiC/CB-containing polymer composites are explored. Some comparison studies are performed to validate the accuracy of the model. It is observed before the percolation threshold that the addition of nanoparticles with a uniform dispersion can improve the electrical conductivity of the polymer composites containing SiC/CB hybrids. Moreover, the results show that the electrical conductivity is more enhanced by the decrease in nanoparticle size. Interestingly, the composite percolation threshold is significantly reduced when SiC whiskers with a higher aspect ratio are added. This work will be favorable for the design of electro-conductive polymer composites with high performances. Full article

Hydrogel nanocomposites that respond to external stimuli and possess switchable electrical properties are considered as emerging materials with potential uses in electrical, electrochemical, and biological devices. This work reports the synthesis and characterization of thermo-responsive and electroconductive hydrogel nanocomposites based on poly(N-isopropylacrylamide) (PNiPAAm) and gold nanoparticles (nanospheres—AuNPs and nanorods—AuNRs) using two different synthetic techniques. Method I involved γ-irradiation-induced crosslinking of a polymer matrix (hydrogel), followed by radiolytic in situ formation of gold nanoparticles, while Method II included the chemical synthesis of nanoparticles, followed by radiolytic formation of a polymer matrix around the gold nanoparticles. UV–Vis spectral studies revealed the presence of local surface plasmon resonance (LSPR) bands characteristic of nanoparticles of different shapes, confirming their formation and stability inside the polymer matrix. Morphological, structural, and physicochemical analyses indicated the existence of a stable porous polymer matrix, the formation of nanoparticles with a face-centered cubic structure, increased swelling capacity, and a slightly higher volume phase transition temperature (VPTT) for the hydrogel nanocomposites. Comparative electrochemical impedance spectroscopy (EIS) showed an increase in conductivity for the nano Au-PNiPAAm hydrogel nanocomposites compared to the PNiPAAm hydrogel, with a considerable rise detected above the VPTT. By reverting to room temperature, the conductivity decreased, indicating that the investigated hydrogel nanocomposites exhibited a remarkable reversible “on–off” thermo-switchable mechanism. The highest conductivity was observed for the sample with rod-shaped gold nanoparticles. The research findings, which include optical, structural, morphological, and physicochemical characterization, evaluation of the efficiency of the chosen synthesis methods, and conductivity testing, provide a starting point for future research on the given nanocomposite materials with integrated multifunctionality. Full article

The current study explores, for the first time, an eco-friendly solution casting method using a green solvent, ethyl acetate, to prepare feedstock/filaments from polylactic acid (PLA) biopolymer reinforced with carbon nanotubes (CNTs), followed by 3D printing and surface activation for biosensing applications. Comprehensive measurements of thermal, electrical, rheological, microstructural, and mechanical properties of developed feedstock and 3D-printed parts were performed and analyzed. Herein, adding 2 wt.% CNTs to the PLA matrix marked the electrical percolation, achieving conductivity of 8.3 × 10⁻³ S.m⁻¹, thanks to the uniform distribution of CNTs within the PLA matrix facilitated by the solution casting method. Rheological assessments paralleled these findings; the addition of 2 wt.% CNTs transitioned the nanocomposite from liquid-like to a solid-like behavior with a percolated network structure, significantly elevating rheological properties compared to the composite with 1 wt.% CNTs. Mechanical evaluations of the printed samples revealed improvement in tensile strength and modulus compared to virgin PLA by a uniform distribution of 2 wt.% CNTs into PLA, with an increase of 14.5% and 10.3%, respectively. To further enhance the electrical conductivity and sensing capabilities of the developed samples, an electrochemical surface activation treatment was applied to as-printed nanocomposite samples. The field-emission scanning electron microscopy (FE-SEM) analysis confirmed that this surface activation effectively exposed the CNTs to the surface of 3D-printed parts by removing a thin layer of polymer from the surface, thereby optimizing the composite’s electroconductivity performance. The findings of this study underscore the potential of the proposed eco-friendly method in developing advanced 3D-printed bio-nanocomposites based on carbon nanotubes and biopolymers, using a green solution casting and cost-effective material extrusion 3D-printing method, for electrochemical-sensing applications. Full article

Electro-conductive films with excellent flexibility and thermal behavior have great potential in the fields of wearable electronics, artificial muscle, and soft robotics. Herein, we report a super-elastic and electro-conductive composite film with a sandwich structure. The composite film was constructed by spraying Polyvinyl alcohol (PVA) polymers onto a buckled conductive carbon nanotube-polydimethylsiloxane (CNTs-PDMS) composite film. In this system, the PVA and PDMS provide water sensing and stretchability, while the coiled CNT film offers sufficient conductivity. Notably, the composite film possesses high stretchability (205%), exceptional compression sensing ability, humility sensing ability, and remarkable electrical stability under various deformations. The produced CNT composite film exhibited deformation (bending/twisting) and high electro-heating performance (108 °C) at a low driving voltage of 2 V. The developed CNT composite film, together with its exceptional sensing and electrothermal performance, provides the material with promising prospects for practical applications in wearable electronics. Full article

A coenzyme A (CoA-SH)-responsive dual electrochemical and fluorescence-based sensor was designed utilizing an MnO₂-immobilized-polymer-dot (MnO₂@D-PD)-coated electrode for the sensitive detection of osteoarthritis (OA) in a peroxisomal β-oxidation knockout model. The CoA-SH-responsive MnO₂@D-PD-coated electrode interacted sensitively with CoA-SH in OA chondrocytes, triggering electroconductivity and fluorescence changes due to cleavage of the MnO₂ nanosheet on the electrode. The MnO₂@D-PD-coated electrode can detect CoA-SH in immature articular chondrocyte primary cells, as indicated by the significant increase in resistance in the control medium (R_24h = 2.17 MΩ). This sensor also sensitively monitored the increase in resistance in chondrocyte cells in the presence of acetyl-CoA inducers, such as phytol (Phy) and sodium acetate (SA), in the medium (R_24h = 2.67, 3.08 MΩ, respectively), compared to that in the control medium, demonstrating the detection efficiency of the sensor towards the increase in the CoA-SH concentration. Furthermore, fluorescence recovery was observed owing to MnO₂ cleavage, particularly in the Phy- and SA-supplemented media. The transcription levels of OA-related anabolic (Acan) and catabolic factors (Adamts5) in chondrocytes also confirmed the interaction between CoA-SH and the MnO₂@D-PD-coated electrode. Additionally, electrode integration with a wireless sensing system provides inline monitoring via a smartphone, which can potentially be used for rapid and sensitive OA diagnosis. Full article

Hydrogels made from conductive organic materials have gained significant interest in recent years due to their wide range of uses, such as electrical conductors, freezing resistors, biosensors, actuators, biomedical engineering materials, drug carrier, artificial organs, flexible electronics, battery solar cells, soft robotics, and self-healers. Nevertheless, the insufficient level of effectiveness in electroconductive hydrogels serves as a driving force for researchers to intensify their endeavors in this domain. This article provides a concise overview of the recent advancements in creating self-healing single- or multi-network (double or triple) conductive hydrogels (CHs) using a range of natural and synthetic polymers and monomers. We deliberated on the efficacy, benefits, and drawbacks of several conductive hydrogels. This paper emphasizes the use of natural polymers and innovative 3D printing CHs-based technology to create self-healing conductive gels for flexible electronics. In conclusion, advantages and disadvantages have been noted, and some potential opportunities for self-healing single- or multi-network hydrogels have been proposed. Full article

An electrochemical sensor sensitive to coenzyme A (CoA) was designed using a CoA-responsive polyallylamine–manganese oxide–polymer dot nanogel coated on the electrode surface to detect various genetic models of osteoarthritis (OA). The CoA-responsive nanogel sensor responded to the abundance of CoA in OA, causing the breakage of MnO₂ in the nanogel, thereby changing the electroconductivity and fluorescence of the sensor. The CoA-responsive nanogel sensor was capable of detecting CoA depending on the treatment time and distinguishing the response towards different OA genetic models that contained different levels of CoA (wild type/WT, NudT7 knockout/N7KO, and Acot12 knockout/A12KO). The WT, N7KO, and A12KO had distinct resistances, which further increased as the incubation time were changed from 12 h (R_12h = 2.11, 2.40, and 2.68 MΩ, respectively) to 24 h (R_24h = 2.27, 2.59, and 2.92 MΩ, respectively) compared to the sensor without treatment (R_control = 1.63 MΩ). To simplify its application, the nanogel sensor was combined with a wireless monitoring device to allow the sensing data to be directly transmitted to a smartphone. Furthermore, OA-indicated anabolic (Acan) and catabolic (Adamts5) factor transcription levels in chondrocytes provided evidence regarding CoA and nanogel interactions. Thus, this sensor offers potential usage in simple and sensitive OA diagnostics. Full article

Due to their electroconductive properties, flexible open-cell polyurethane foam/silver nanowire (PUF/AgNW) structures can provide an alternative for the construction of cheap pressure transducers with limited lifetimes or used as filter media for air conditioning units, presenting bactericidal and antifungal properties. In this paper, highly electroconductive metal-polymer hybrid foams (MPHFs) based on AgNWs were manufactured and characterized. The electrical resistance of MPHFs with various degrees of AgNW coating was measured during repeated compression. For low degrees of AgNW coating, the decrease in electrical resistance during compression occurs in steps and is not reproducible with repeated compression cycles due to the reduced number of electroconductive zones involved in obtaining electrical conductivity. For high AgNW coating degrees, the decrease in resistance is quasi-linear and reproducible after the first compression cycle. However, after compression, cracks appear in the foam cell structure, which increases the electrical resistance and decreases the mechanical strength. It can be considered that PUFs coated with AgNWs have a compression memory effect and can be used as cheap solutions in industrial processes in which high precision is not required, such as exceeding a maximum admissible load or as ohmic seals for product security. Full article

Fish skin is a by-product of the fishing industry, which has become a significant environmental pollutant in recent years. Therefore, there is an emerging interest in developing novel technologies to utilize fish skin as a versatile raw material for the clothing and biomedical industries. Most research on finishing procedures is conducted on cattle leather, and practically very limited information on fish leather finishing is found in the literature. We have developed three functional surface finishing treatments on chromium (CL)- and vegetable (VL)- tanned salmon leather. These treatments include hydrophobic, oil repellent, and electro-conductive ones. The hydroxyl functional groups present on the surface of the leather were covalently grafted with bi-functional aliphatic small molecule, 10-undecenoylchloride (UC), by esterification reaction forming hydrophobic coating. The surface hydrophobicity was further increased via covalent binding of perfluorodecanethiol (PFDT) to the double bond end-groups of the UC-modified leather via thiol-ene click chemistry conditions. The oleophobic coating was successfully developed using synthesized fluorinated silica nanoparticles (FSN) and polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), showing oil repellency with a contact angle of about 100° for soybean oil and n-hexadecane. The electrically conductive coating was realized by the incorporation of conjugated polymer, polyaniline (PANI), via in situ polymerization method. The treated leather exhibited surface resistivity of about 5.2 (Log (Ω/square)), much lower than untreated leather with a resistivity of 11.4 (Log (Ω/square)). Full article

This study describes, for the first time, the successful incorporation of poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) in Poly(acrylonitrile) (PAN) fibers. While electroconductive PEDOT:PSS is extremely challenging to electrospun into fibers. Therefore, PAN, a polymer easy to electrospun, was chosen as a carrier due to its biocompatibility and tunable chemical stability when cross-linked, particularly using strong acids. PAN:PEDOT:PSS blends, prepared from PEDOT:PSS Clevios PH1000, were electrospun into fibers (PH1000) with a diameter of 515 ± 120 nm, which after being thermally annealed (PH1000 24H) and treated with heated sulfuric acid (PH1000 H₂SO₄), resulted in fibers with diameters of 437 ± 109 and 940 ± 210 nm, respectively. The fibers obtained over the stepwise process were characterized through infra-red/Raman spectroscopy and cyclic voltammetry. The final fiber meshes showed enhanced electroconductivity (3.2 × 10⁻³ S cm⁻¹, four-points-assay). Fiber meshes biocompatibility was evaluated using fibroblasts and neural stem cells (NSCs) following, respectively, the ISO10993 guidelines and standard adhesion/proliferation assay. NSCs cultured on PH1000 H₂SO₄ fibers presented normal morphology and high proliferation rates (0.37 day⁻¹ vs. 0.16 day⁻¹ for culture plate), indicating high biocompatibility for NSCs. Still, the low initial NSC adhesion of 7% calls for improving seeding methodologies. PAN:PEDOT:PSS fibers, here successful produced for the first time, have potential applications in neural tissue engineering and soft electronics. Full article

Composites based on polyacrylic acid gels as matrices and conducting polymers (polyaniline and polypyrrole) as functional components have been obtained. It has been shown that the dependence of the equilibrium degree of swelling on the pH medium for the matrices demonstrates its pronounced maximum at pH = 11. The reversibility of the processes of swelling/contraction for the matrices and composites over a wide variation of swelling medium acidities was studied and analyzed. The effect of the crosslinking degree of the matrix on the content of the conducting components in the composites was determined. The electric conductivity of the composites depended on the degree of crosslinking of the matrices, and the content of the conducting component was measured. Deformational characteristics at compression were measured for the matrices and composites prepared in block-shaped cylinders. It was proven that the formation of a rigid-chain conducting polymer phase in the composites led to an increase in the elastic modulus as compared with the one for the matrix gel, but it did not cause a noticeable decrease in elasticity. It was observed that the new composites were characterized by a combination of swelling capacity, pH sensitivity, and electroconductivity. Full article

Electrical stimulation is a powerful strategy to improve the differentiation of neural stem cells into neurons. Such an approach can be implemented, in association with biomaterials and nanotechnology, for the development of new therapies for neurological diseases, including direct cell transplantation and the development of platforms for drug screening and disease progression evaluation. Poly(aniline):camphorsulfonic acid (PANI:CSA) is one of the most well-studied electroconductive polymers, capable of directing an externally applied electrical field to neural cells in culture. There are several examples in the literature on the development of PANI:CSA-based scaffolds and platforms for electrical stimulation, but no review has examined the fundamentals and physico-chemical determinants of PANI:CSA for the design of platforms for electrical stimulation. This review evaluates the current literature regarding the application of electrical stimulation to neural cells, specifically reviewing: (1) the fundamentals of bioelectricity and electrical stimulation; (2) the use of PANI:CSA-based systems for electrical stimulation of cell cultures; and (3) the development of scaffolds and setups to support the electrical stimulation of cells. Throughout this work, we critically evaluate the revised literature and provide a steppingstone for the clinical application of the electrical stimulation of cells using electroconductive PANI:CSA platforms/scaffolds. Full article

The preparation of an electroactive matrix for the immobilization of the bioprobe shows great promise to construct the label-free biosensors. Herein, the electroactive metal-organic coordination polymer has been in-situ prepared by pre-assembly of a layer of trithiocynate (TCY) on a gold electrode (AuE) through Au-S bond, followed by repetitive soaking in Cu(NO₃)₂ solution and TCY solutions. Then the gold nanoparticles (AuNPs) and the thiolated thrombin aptamers were successively assembled on the electrode surface, and thus the electrochemical electroactive aptasensing layer for thrombin was achieved. The preparation process of the biosensor was characterized by an atomic force microscope (AFM), attenuated total reflection-Fourier transform infrared (ATR-FTIR), and electrochemical methods. Electrochemical sensing assays showed that the formation of the aptamer-thrombin complex changed the microenvironment and the electro-conductivity of the electrode interface, causing the electrochemical signal suppression of the TCY-Cu²⁺ polymer. Additionally, the target thrombin can be label-free analyzed. Under optimal conditions, the aptasensor can detect thrombin in the concentration range from 1.0 fM to 1.0 μM, with a detection limit of 0.26 fM. The spiked recovery assay showed that the recovery of the thrombin in human serum samples was 97.2–103%, showing that the biosensor is feasible for biomolecule analysis in a complex sample. Full article

In this study, morphology and in vitro response of electroconductive composite nanofibers were explored for biomedical use. The composite nanofibers were prepared by blending the piezoelectric polymer poly(vinylidene fluoride–trifluorethylene) (PVDF-TrFE) and electroconductive materials with different physical and chemical properties such as copper oxide (CuO), poly(3-hexylthiophene) (P3HT), copper phthalocyanine (CuPc), and methylene blue (MB) resulting in unique combinations of electrical conductivity, biocompatibility, and other desirable properties. Morphological investigation via SEM analysis has remarked some differences in fiber size as a function of the electroconductive phase used, with a reduction of fiber diameters for the composite fibers of 12.43% for CuO, 32.87% for CuPc, 36.46% for P3HT, and 63% for MB. This effect is related to the peculiar electroconductive behavior of fibers: measurements of electrical properties showed the highest ability to transport charges of methylene blue, in accordance with the lowest fibers diameters, while P3HT poorly conducts in air but improves charge transfer during the fiber formation. In vitro assays showed a tunable response of fibers in terms of viability, underlining a preferential interaction of fibroblast cells to P3HT-loaded fibers that can be considered the most suitable for use in biomedical applications. These results provide valuable information for future studies to be addressed at optimizing the properties of composite nanofibers for potential applications in bioengineering and bioelectronics. Full article