A review of the interfacial characteristics of polymer nanocomposites containing carbon nanotubes

Advancements in carbon nanotube-polymer composites: Enhancing properties and applications through advanced manufacturing techniques

Carbon nanotube (CNT)-polymer composites exhibit significant advancements in mechanical, electrical, and thermal properties, enabling numerous promising applications. This review delves into recent research on manufacturing methods, filament extrusion, additive manufacturing (AM), properties, and applications of CNT polymer composites. Factors like processing conditions, polymer types, and CNT concentrations determine the ultimate properties of the composite material. The dispersion of CNT within various manufacturing techniques, such as melt mixing, solution mixing, and in-situ polymerization, significantly impacts the properties of the composite material. These composite materials are extensively used in AM, particularly in 3D printing, where filament blends are extruded and printed to custom-shaped objects. The finding underscores the effect of CNT content on the properties of CNT-polymer composite material in different applications. However, gaps remain in optimizing manufacturing processes and AM techniques, essential for tailoring these composites to specific application needs. Future research should focus on developing cost-effective and scalable manufacturing methods to unlock the full potential of CNT-polymer composites in various industries.

Composite Nanomaterials Based on Polymethylmethacrylate Doped with Carbon Nanotubes and Nanoparticles: A Review

Composite polymer materials have high strength and lightness, which makes them attractive for use in a variety of structures and products. The present article contains an overview of modern works devoted to the production of composite materials based on poly(methyl methacrylate) (PMMA) with improved characteristics. The possibility of obtaining such materials can be a key area for creating more efficient and durable products in various industries. Various methods were considered to improve the characteristics of PMMA by doping the polymer matrix with carbon nanotubes (CNTs), graphite, nanohydroxyapatite particles, micro-zirconia nanoparticles, titanium dioxide, etc. The possibilities of using the obtained composite materials in various industries such as aviation, automotive, construction, medical and others are discussed. This article also presents the results of our own research on the mechanisms of interaction of PMMA with single-layer CNTs, leading to the creation of a composite polymer system "PMMA+CNT", achieved using the modern quantum chemical method DFT. This article presents a review of the recent research on the effect of CNTs on the mechanical and electrically conductive properties of nanocomposite materials. The outcomes of this study can be important for the development of science and technology in various fields, from fundamental chemistry to applied scientific research.

Metal oxide nanomaterials based electrochemical and optical biosensors for biomedical applications: Recent advances and future prospectives

The amalgamation of nanostructures with modern electrochemical and optical techniques gave rise to interesting devices, so-called biosensors. A biosensor is an analytical tool that incorporates various biomolecules with an appropriate physicochemical transducer. Over the past few years, metal oxide nanomaterials (MONMs) have significantly stimulated biosensing research due to their desired functionalities, versatile chemical stability, and low cost along with their unique optical, catalytic, electrical, and adsorption properties that provide an attractive platform for linking the biomolecules, for example, antibodies, nucleic acids, enzymes, and receptor proteins as sensing elements with the transducer for the detection of signals or signal amplifications. The signals to be measured are in direct proportionate to the concentration of the bioanalyte. Because of their simplicity, cost-effectiveness, portability, quick analysis, higher sensitivity, and selectivity against a broad range of biosamples, MONMs-based electrochemical and optical biosensing platforms are exhaustively explored as powerful early-diagnosis tools for point of care applications. Herein, we made a bibliometric analysis of past twenty years (2004-2023) on the application of MONMs as electrochemical and optical biosensing units using Web of Science database and the results of which clearly reveal the increasing number of publications since 2004. Geographical area distribution analysis of these publications shows that China tops the list followed by the United States of America and India. In this review, we first describe the electrochemical and optical properties of MONMs that are crucial for the creation of extremely stable, specific, and sensitive sensors with desirable characteristics. Then, the biomedical applications of MONMs-based bare and hybrid electrochemical and optical biosensing frameworks are highlighted in the light of recent literature. Finally, current limitations and future challenges in the field of biosensing technology are addressed.

Hydrogen bond-mediated self-assembly of Tin (II) oxide wrapped with Chitosan/[BzPy]Cl network: An effective bionanocomposite for textile wastewater remediation

A novel and efficient bionanocomposite was synthesized by incorporating SnO into chitosan (Ch) and a room-temperature ionic liquid (RTIL). The bionanocomposite was synthesized in benzoyl pyridinium chloride [BzPy]Cl to maintain the unique properties of SnO, chitosan, and the ionic liquid. Adsorption and photodegradation processes were applied to evaluate the bionanocomposite for removing azo and anthraquinone dyes and textile wastewater. SnO/[BzPy]Cl and SnO/[BzPy]Cl/Ch samples were prepared and characterized using various techniques, including FT-IR, SEM, XRD, EDAX, XPS, DSC, TGA, nitrogen adsorption/desorption isotherm, and DRS analysis. SEM analysis revealed a hierarchical roughened rose flower-like morphology for the biocomposite. The band gap energies of SnO/[BzPy]Cl and SnO/[BzPy]Cl/chitosan were found to be 3.9 and 3.3 eV, respectively, indicating a reduction in the band gap energy with the introduction of [BzPy]Cl and chitosan. SnO/[BzPy]Cl/Ch showed high removal rates (92-95 %) for Fast Red, Blue 15, Red 120, Blue 94, Yellow 160, and Acid Orange 7 dyes. The adsorption kinetics followed a pseudo-second-order model. In addition, the effect of different photodegradation parameters such as solution pH, dye concentrations, contact time, and amount of photocatalyst, was studied. Given the optimal results obtained in removing azo and anthraquinone dyes, the SnO/[BzPy]Cl/Ch nanocomposite was used as an efficient nanocomposite for removing dyes from textile wastewater. The highest removal efficiency was found to be 95.8 %, obtained under ultraviolet and visible light. Furthermore, BOD and COD reduction analysis showed significant reductions, indicating the excellent performance of the photocatalyst.

Interlocking Matrix and Filler for Enhanced Individualization and Reinforcement in Polymer-Single-Walled Carbon Nanotube Composites

Poor individualization and interfacial adhesion prevent single-walled carbon nanotube (SWNT)-polymer composites from reaching outstanding mechanical properties. With much larger diameters, but common structural features (high aspect ratio and absence of functional groups for covalent or supramolecular attachment with the polymer), carbon fibers face similar problems, which are addressed by covering the fibers with a thin layer of polymer. This sizing strategy has allowed carbon fibers to become the filler of choice for the highest performing materials. Inspired by this, here we investigate the use of the mechanical bond to wrap SWNTs with a layer of polymeric material to produce SWNTs mechanically interlocked with a layer of polymer. We first validate the formation of mechanically interlocked nanotubes (MINTs) using mixtures of SWNTs of relatively large average diameter (1.6 ± 0.4 nm), which are commercially available at reasonable prices and therefore could be technologically relevant as polymer fillers. We then design and synthesize by ring-opening metathesis polymerization (ROMP) a polymer decorated with multiple U-shaped molecules, which are later ring-closed around the SWNTs using metathesis. The obtained hybrids contain a high degree of individualized SWNTs and exhibit significantly increased mechanical properties when compared to the matrix polymer. We envision that this strategy could be employed to produce SWNTs interlocked with polymer layers with various designs for polymer reinforcement.

Dynamic Assembly of Strong and Conductive Carbon Nanotube/Nanocellulose Composite Filaments and Their Application in Resistive Liquid Sensing

The continuous flow assembly of colloidal nanoparticles from aqueous suspensions into macroscopic materials in a field-assisted double flow focusing system offers an attractive way to bridge the outstanding nanoscale characteristics of renewable cellulose nanofibrils (CNFs) at scales most common to human technologies. By incorporating single-walled carbon nanotubes (SWNTs) during the fabrication process, high-performance functional filament nanocomposites were produced. CNFs and SWNTs were first dispersed in water without any external surfactants or binding agents, and the resulting nanocolloids were aligned by means of an alternating electric field combined with extensional sheath flows. The nanoscale orientational anisotropy was then locked by a liquid-gel transition during the materials assembly into macroscopic filaments, which greatly improved their mechanical, electrical, and liquid sensing properties. Significantly, these findings pave the way toward the environmentally friendly and scalable manufacturing of a variety of multifunctional fibers for diverse applications.

Exploring thermodynamic and structural properties of carbon nanotube/thermoplastic polyurethane nanocomposites from atomistic molecular dynamics simulations

Carbon nanotubes (CNTs) and thermoplastic polyurethane (TPU) nanocomposites have emerged as promising materials for various applications in the field of nanotechnology. An understanding of the thermodynamic and structural properties is of fundamental significance in designing and fabricating CNT/TPU nanocomposites with desired properties. To this end, this work has employed atomistic molecular dynamics (MD) simulations to study the thermal properties and interfacial characteristics of TPU composites filled with pristine or functionalized single-walled carbon nanotubes (SWNTs). Simulations reveal that the introduction of SWNTs suppresses TPU chain dynamics and favors the hydrogen bond formation induced by the wrapping of TPU chains around SWNTs, leading to an increase of glass transition temperature (T_g) and a reduction of volumetric coefficient of thermal expansion (CTE) in the rubbery state. Compared to pristine and hydrogenated SWNTs, SWNTs featuring polar groups, such as carboxyl (-COOH), oxhydryl (-OH) and amine (-NH₂) groups, show improved affinity for TPU molecules, suppressing polymer mobility. Analysis of SWNT/TPU binding energy and solubility parameter suggests that electrostatic interactions are responsible for such a functionalized SWNT/TPU interface enhancement. Furthermore, the amine groups exhibit the highest potential for forming hydrogen bonds with the urethane carbonyl (-C[double bond, length as m-dash]O) of TPU chains, resulting in lowest polymer mobility and highest T_g. In general, this research work could provide some guidance for material design of polymer nanocomposites and future simulations relevant to TPUs.

Thermal and Dielectric Investigations of Polystyrene Nanoparticles as a Viable Platform-Toward the Next Generation of Fillers for Nanocomposites

Nanoparticles are often used as fillers for enhancing various properties of polymer composites such as mechanical, electrical, or dielectric. Among them, polymer nanoparticles are considered ideal contenders because of their compatibility with a polymer matrix. For this reason, it is important that they are synthesized in a surfactant-free form, to obtain predictable surface and structural properties. Here, we synthesized a series of polystyrene nanoparticles (PS NPs), by emulsion polymerization of styrene, using varying amounts of divinylbenzene as a crosslinking agent and sodium 4-vinylbenzenesulfonate as a copolymerizing monomer surfactant-"surfmer". Using "surfmers" we obtained surfactant-free nanoparticles that are monodisperse, with a high degree of thermal stability, as observed by scanning electron microscopy and thermogravimetric investigations. The prepared series of NPs were investigated by means of broadband dielectric spectroscopy and we demonstrate that by fine-tuning their chemical composition, fine changes in their dielectric and thermal properties are obtained. Further, we demonstrate that the physical transformations in the nanoparticles, such as the glass transition, can be predicted by performing the first derivative of dielectric permittivity for all investigated samples. The glass transition temperature of PS NPs appears to be inversely correlated with the dielectric permittivity and the average diameter of NPs.

Influence of the type of substrate on the properties of carbon nanotubes layer studied by Raman spectroscopy

The development of nanomaterials technology allows to design a novel medical strategies, and could also be useful in the field of regenerative medicine. The paper presents a study on the functionalized multi-walled carbon nanotubes (MWCNTs-f) layers deposited by electrophoretic method (EPD) on the surfaces of two types of substrates: titanium (Ti) and stainless steel. SEM and EDS analyses confirm that incubation in a simulated body fluid (SBF) caused a formation of hydroxyapatite on the surface of the Ti/MWCNTs-f. Raman micro-spectroscopy was a method of choice to study presented materials. The MWCNTs-f layer on the surface of the titanium plate shows better layer order than the corresponding layer deposited on the stainless steel. The structure and ordering of the nanocarbon layer play a key role in the biological activity of the materials. This was confirmed by the incubation of the plates with deposited layer of carbon nanotubes in SBF. A titanium substrate with a MWCNTs-f layer supports the deposition of some components from the environment, while a stainless steel substrate promotes the formation of a carbon film that inhibits the deposition of certain components from the environment. A two-trace two-dimensional (2T2D) analysis confirmed a different effect of SBF on the MWCNTs-f layer depending on the type of substrate. The MWCNTs-f layer on titanium substrate seems to represent an interesting proposition for novel bioactive strategies.

MWCNTs-GNPs Reinforced TPU Composites with Thermal and Electrical Conductivity: Low-Temperature Controlled DIW Forming

As an effective technique for fabricating conductive and thermally conductive polymer composites, a multi-filler system incorporates different types and sizes of multiple fillers to form interconnected networks with improved electrical, thermal, and processing properties. In this study, DIW forming of bifunctional composites was achieved by controlling the temperature of the printing platform. The study was based on enhancing the thermal and electrical transport properties of hybrid ternary polymer nanocomposites with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplates (GNPs). With thermoplastic polyurethane (TPU) used as the matrix, the addition of MWCNTs, GNPs and both mixtures further improved the thermal conductivity of the elastomers. By adjusting the weight fraction of the functional fillers (MWCNTs and GNPs), the thermal and electrical properties were gradually explored. Here, the thermal conductivity of the polymer composites increased nearly sevenfold (from 0.36 W·m^-1·k^-1 to 2.87 W·m^-1·k^-1) and the electrical conductivity increased up to 5.49 × 10^-2 S·m^-1. It is expected to be used in the field of electronic packaging and environmental thermal dissipation, especially for modern electronic industrial equipment.

Framing of Poly(arylene-ethynylene) around Carbon Nanotubes and Iodine Doping for the Electrochemical Detection of Dopamine

Dopamine (DA), an organic biomolecule that acts as both a hormone and a neurotransmitter, is essential in regulating emotions and metabolism in living organisms. The accurate determination of DA is important because it indicates early signs of serious neurological disorders. Covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) have received considerable attention in recent years as promising porous materials with an unrivaled degree of tunability for electrochemical biosensing applications. This study adopted a solvothermal strategy for the synthesis of a conjugated microporous poly(arylene ethynylene)-4 (CMP-4) network using the Sonagashira-Hagihara cross-coupling reaction. To increase the crystallinity and electrical conductivity of the material, CMP-4 was enveloped around carbon nanotubes (CNTs), followed by iodine doping. When used as an electrochemical probe, the as-synthesized material (I2-CMP-CNT-4) exhibited excellent selectivity and sensitivity to dopamine in the phosphate-buffered solution. The detection limits of the electrochemical sensor were 1 and 1.7 μM based on cyclic voltammetry (CV) and differential pulse voltammetry (DPV).

A study of the interactions between human osteoblast-like cells and polymer composites with functionalized graphene derivatives using 2D correlation spectroscopy (2D-COS)

In response to the growing need for development of modern biomaterials for applications in regenerative medicine strategies, the research presented here investigated the biological potential of two types of polymer nanocomposites. Graphene oxide (GO) and partially reduced graphene oxide (rGO) were incorporated into a poly(ε-caprolactone) (PCL) matrix, creating PCL/GO and PCL/rGO nanocomposites in the form of membranes. Proliferation of osteoblast-like cells (human U-2 OS cell line) on the surface of the studied materials confirmed their biological activity. Fluorescence microscopy was able to distinguish the different patterns of interaction between cells (depending on the type of material) after 15 days of the test run. Raman micro-spectroscopy and two-dimensional correlation spectroscopy (2D-COS) applied to Raman spectra distinguished the nature of cell-material interactions after only 8 days. Combination of these two techniques (Raman micro-spectroscopy and 2D-COS analysis) facilitated identification of a much more complex cellular response (especially from proteins) on the surface of PCL/GO. The presented approach can be regarded as a method for early study of the bioactivity of membrane materials.

Non-covalent modification of single wall carbon nanotubes (SWCNTs) by thienothiophene derivatives

Non-covalent functionalization of single wall carbon nanotubes (SWCNTs) has been conducted using several binding agents with surface π-interaction forces in recent studies. Herein, we present the first example of non-covalent functionalization of sidewalls of SWCNTs using thienothiophene (TT) derivatives without requiring any binding agents. Synthesized TT derivatives, TT-CN-TPA, TT-CN-TPA2 and TT-COOH-TPA, were attached directly to SWCNTs through non-covalent interactions to obtain new TT-based SWCNT hybrids, HYBRID 1-3. Taking advantage of the presence of sulfur atoms in the structure of TT, HYBRID 1, as a representative, was treated with Au nanoparticles for the adsorption of Au by sulfur atoms, which generated clear TEM images of the particles. The images indicated the attachment of TTs to the surface of SWCNTs. Thus, the presence of sulfur atoms in TT units made the binding of TTs to SWCNTs observable via TEM analysis through adsorption of Au nanoparticles by the sulfur atoms. Surface interactions between TTs and SWCNTs of the new hybrids were also clarified by classical molecular dynamic simulations, a quantum mechanical study, and SEM, TEM, AFM and contact angle (CA) analyses. The minimum distance between a TT and a SWCNT reached up to 3.5 Å, identified with strong peaks on a radial distribution function (RDF), while maximum interaction energies were raised to -316.89 kcal mol^-1, which were determined using density functional theory (DFT).

Thermal, Mechanical, and Morphological Characterisations of Graphene Nanoplatelet/Graphene Oxide/High-Hard-Segment Polyurethane Nanocomposite: A Comparative Study

The current work investigates the effect of the addition of graphene nanoplatelets (GNPs) and graphene oxide (GO) to high hard-segment polyurethane (75% HS) on its thermal, morphological, and mechanical properties. Polyurethane (PU) and its nanocomposites were prepared with different ratios of GNP and GO (0.25, 0.5, and 0.75 wt.%). A thermal stability analysis demonstrated an enhancement in the thermal stability of PU with GNP and GO incorporated compared to pure PU. Differential Scanning Calorimetry (DSC) showed that both GNP and GO act as heterogeneous nucleation agents within a PU matrix, leading to an increase in the crystallinity of PU. The uniform dispersion and distribution of GNP and GO flakes in the PU matrix were confirmed by SEM and TEM. In terms of the mechanical properties of the PU nanocomposites, it was found that the interaction between PU and GO was better than that of GNP due to the functional groups on the GO's surface. This leads to a significant increase in tensile strength for 0.5 wt.% GNP and GO compared with pure PU. This can be attributed to interfacial interaction between the GO and PU chains, resulting in an improvement in stress transferring from the matrix to the filler and vice versa. This work sheds light on the understanding of the interactions between graphene-based fillers and their influence on the mechanical properties of PU nanocomposites.

Fabrication and characterization of novel polyhydroxybutyrate-keratin/nanohydroxyapatite electrospun fibers for bone tissue engineering applications

The role of scaffolds in bone regeneration is of great importance. Here, the electrospun scaffolds of poly (3-hydroxybutyrate)-keratin (PHB-K)/nanohydroxyapatite (nHA) with different morphologies (long nanorods (HAR) and very short nanorods (HAP)) and weight percentages (up to 10 w/w%) of nHA were fabricated and characterized. The fibers integrity, the porosity of above 80%, and increase in pore size up to 16 μm were observed by adding nHA. The nanofibers crystallinity increased by 13.5 and 22.8% after the addition of HAR and HAP, respectively. The scaffolds contact angle decreased by almost 20° and 40° after adding 2.5 w/w% HAR and HAP, respectively. The tensile strength of the scaffolds increased from 2.99 ± 0.3 MPa for PHB-K to 6.44 ± 0.16 and 9.27 ± 0.04 MPa for the scaffolds containing 2.5 w/w% HAR and HAP, respectively. After immersing the scaffolds into simulated body fluid (SBF), the Ca concentration decreased by 55% for HAR- and 73% for HAP-containing scaffolds, showing the bioactivity of nHA-containing scaffolds. The results of cell attachment, proliferation, and viability of MG-63 cells cultured on the nanocomposites showed the positive effects of nHA. The results indicate that the nanocomposite scaffolds, especially HAP-containing ones, can be suitable for bone tissue engineering applications.

Wearable Sensors for Healthcare: Fabrication to Application

This paper presents a substantial review of the deployment of wearable sensors for healthcare applications. Wearable sensors hold a pivotal position in the microelectronics industry due to their role in monitoring physiological movements and signals. Sensors designed and developed using a wide range of fabrication techniques have been integrated with communication modules for transceiving signals. This paper highlights the entire chronology of wearable sensors in the biomedical sector, starting from their fabrication in a controlled environment to their integration with signal-conditioning circuits for application purposes. It also highlights sensing products that are currently available on the market for a comparative study of their performances. The conjugation of the sensing prototypes with the Internet of Things (IoT) for forming fully functioning sensorized systems is also shown here. Finally, some of the challenges existing within the current wearable systems are shown, along with possible remedies.

UV-LED Curable Acrylic Films Containing Phosphate Glass Powder: Effect of the Filler Loading on the Thermal, Optical, Mechanical and Flame Retardant Properties

In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading was changed within 10 and 50 wt.%. UV-LED initiated curing was selected as a fast and reliable system, as the standard UV-curing process was not suitable because of the presence of the glass powder that decreased the quantum efficiency during the UV exposure, hence preventing the transformation of the liquid system into a solid network. The glass powder slightly increased the glass transition temperature of the acrylic network, hence showing a limited effect on the chain segments mobility; besides, increasing filler loadings were responsible for a progressive decrease of the transparency of films, irrespective of a marginal effect on their refractive index. Conversely, the presence of increasing amounts of phosphate glass improved the thermal and thermo-oxidative stability of the cured products. Besides, phosphate glass was capable of remarkably enhancing the flame retardance of the acrylic network at 50 wt.% loading, which achieved self-extinction in vertical flame spread tests (and was V-0 rated). This formulation, as assessed by forced-combustion tests, also displayed a remarkable decrease of peak of Heat Release Rate and Total Heat Release (by 44 and 33%, respectively) and of Total Smoke Release and Specific Extinction Area (by 53 and 56%, respectively). Further, the filler promoted an increase of the stiffness and surface hardness of the films, at the expense of a decrease in ductility. All these findings may justify the potential use of these composite films as flame retardant coatings for different flammable substrates.

Fabrication, thermal analysis, and heavy ion irradiation resistance of epoxy matrix nanocomposites loaded with silane-functionalized ceria nanoparticles

This paper describes a detailed understanding of how nanofillers function as radiation barriers within the polymer matrix, and how their effectiveness is impacted by factors such as composition, size, loading, surface chemistry, and dispersion. We designed a comprehensive investigation of heavy ion irradiation resistance in epoxy matrix composites loaded with surface-modified ceria nanofillers, utilizing tandem computational and experimental methods to elucidate radiolytic damage processes and relate them to chemical and structural changes observed through thermal analysis, vibrational spectroscopy, and electron microscopy. A detailed mechanistic examination supported by FTIR spectroscopy data identified the bisphenol A moiety as a primary target for degradation reactions. Results of computational modeling by the Stopping Range of Ions in Matter (SRIM) Monte Carlo simulation were in good agreement with damage analysis from surface and cross-sectional SEM imaging. All metrics indicated that ceria nanofillers reduce the damage area in polymer nanocomposites, and that nanofiller loading and homogeneity of dispersion are key to effective damage prevention. The results of this study represent a significant pathway for engineered irradiation tolerance in a diverse array of polymer nanocomposite materials. Numerous areas of materials science can benefit from utilizing this facile and effective method to extend the reliability of polymer materials.

Recent Progress in Graphene- and Related Carbon-Nanomaterial-based Electrochemical Biosensors for Early Disease Detection

Graphene- and carbon-based nanomaterials are key materials to develop advanced biosensors for the sensitive detection of many biomarkers owing to their unique properties. Biosensors have attracted increasing interest because they allow efficacious, sensitive, selective, rapid, and low-cost diagnosis. Biosensors are analytical devices based on receptors for the process of detection and transducers for response measuring. Biosensors can be based on electrochemical, piezoelectric, thermal, and optical transduction mechanisms. Early virus identification provides critical information about potentially effective and selective therapies, extends the therapeutic window, and thereby reduces morbidity. The sensitivity and selectivity of graphene can be amended via functionalizing it or conjoining it with further materials. Amendment of the optical and electrical features of the hybrid structure by introducing appropriate functional groups or counterparts is especially appealing for quick and easy-to-use virus detection. Various techniques for the electrochemical detection of viruses depending on antigen-antibody interactions or DNA hybridization are discussed in this work, and the reasons behind using graphene and related carbon nanomaterials for the fabrication are presented and discussed. We review the existing state-of-the-art directions of graphene-based classifications for detecting DNA, protein, and hormone biomarkers and summarize the use of the different biosensors to detect several diseases, like cancer, Alzheimer's disease, and diabetes, to sense numerous viruses, including SARS-CoV-2, human immunodeficiency virus, rotavirus, Zika virus, and hepatitis B virus, and to detect the recent pandemic virus COVID-19. The general concepts, mechanisms of action, benefits, and disadvantages of advanced virus biosensors are discussed to afford beneficial evidence of the creation and manufacture of innovative virus biosensors. We emphasize that graphene-based nanomaterials are ideal candidates for electrochemical biosensor engineering due to their special and tunable physicochemical properties.

Biomaterials Based on Carbon Nanotube Nanocomposites of Poly(styrene-b-isobutylene-b-styrene): The Effect of Nanotube Content on the Mechanical Properties, Biocompatibility and Hemocompatibility

Nanocomposites based on poly(styrene-block-isobutylene-block-styrene) (SIBS) and single-walled carbon nanotubes (CNTs) were prepared and characterized in terms of tensile strength as well as bio- and hemocompatibility. It was shown that modification of CNTs using dodecylamine (DDA), featured by a long non-polar alkane chain, provided much better dispersion of nanotubes in SIBS as compared to unmodified CNTs. As a result of such modification, the tensile strength of the nanocomposite based on SIBS with low molecular weight (Mn = 40,000 g mol-1) containing 4% of functionalized CNTs was increased up to 5.51 ± 0.50 MPa in comparison with composites with unmodified CNTs (3.81 ± 0.11 MPa). However, the addition of CNTs had no significant effect on SIBS with high molecular weight (Mn~70,000 g mol-1) with ultimate tensile stress of pure polymer of 11.62 MPa and 14.45 MPa in case of its modification with 1 wt% of CNT-DDA. Enhanced biocompatibility of nanocomposites as compared to neat SIBS has been demonstrated in experiment with EA.hy 926 cells. However, the platelet aggregation observed at high CNT concentrations can cause thrombosis. Therefore, SIBS with higher molecular weight (Mn~70,000 g mol-1) reinforced by 1-2 wt% of CNTs is the most promising material for the development of cardiovascular implants such as heart valve prostheses.

Troponin I as a Biomarker for Early Detection of Acute Myocardial Infarction

Acute myocardial infarction (AMI) as the main cause of death among cardiovascular diseases is defined as a deficiency of oxygen that generates irreversible tissue necrosis in the heart muscle. For diagnostic measurements, the evaluation of cardiac markers concentration like cardiac triponin I (cTnI) in plasma or saliva thought the use of biosensors has become one of the most commonly applied strategies for prognosis of AMI. Inside this diagnostic devices, electrochemical (ECL) ones have been highly encourage to improve sensing capabilities by using different materials and configurations. In this review, the authors presents a summary of studies that involves cTnI detection using ECL biosensors modified with nanomaterials and related mechanisms.

Effect of Cyrtostachys renda Fiber Loading on the Mechanical, Morphology, and Flammability Properties of Multi-Walled Carbon Nanotubes/Phenolic Bio-Composites

This research focuses on evaluating the effect of Cyrtostachys renda (CR) fiber and the impact of adding multi-walled carbon nanotubes (MWCNT) on the morphological, physical, mechanical, and flammability properties of phenolic composites. MWCNT were supplemented with phenolic resin through a dry dispersion ball milling method. Composites were fabricated by incorporating CR fiber in 0.5 wt.% MWCNT-phenolic matrix by hot pressing. Nevertheless, the void content, higher water absorption, and thickness swelling increased with fiber loading to the MWCNT/phenolic composites. The presence of MWCNT in phenolic enhanced the tensile, flexural, and impact strength by as much as 18%, 8%, and 8%, respectively, compared to pristine phenolic. The addition of CR fiber, however, strengthened MWCNT-phenolic composites, improving the tensile, flexural, and impact strength by as much as 16%, 16%, and 266%, respectively, for 50 wt.% loading of CR fiber. The CR fiber may adhere properly to the matrix, indicating that there is a strong interface between fiber and MWCNT-phenolic resin. UL-94 horizontal and limiting oxygen index (LOI) results indicated that all composite materials are in the category of self-extinguishing. Based on the technique for order preference by similarity to the ideal solution (TOPSIS) technique, 50 wt.% CR fiber-reinforced MWCNT-phenolic composite was chosen as the optimal composite for mechanical and flammability properties. This bio-based eco-friendly composite has the potential to be used as an aircraft interior component.

Carbon Nanotube Scaffolds Entrapped in a Gel Matrix for Realizing the Improved Cycle Life of Zinc Bromine Redox Flow Batteries

Herein, we have successfully demonstrated a nanofiller (such as multiwalled carbon nanotubes (MWCNT)) dispersed in a polymer matrix (such as polyacrylonitrile (PAN)) as an effective pore filling agent to a microporous Daramic membrane for inhibiting bromine diffusion in zinc bromine redox flow batteries. A simple protocol of the MWCNT/PAN-Daramic membrane renders a major benefit for inhibiting bromine diffusion relative to the conventional microporous membrane. As a result, the MWCNT/PAN composite Daramic membrane exhibits remarkable electrochemical performance in zinc bromine redox flow batteries at various current densities. More impressively, the MWCNT/PAN composite Daramic membrane shows a 90% Coulombic efficiency compared to the pristine Daramic membrane and the PAN composite Daramic membrane with only 68.53 and 71.20% efficiencies at 160 mA cm^-2, respectively. Moreover, the MWCNT/PAN composite Daramic membrane displays an extraordinary long cycling performance with a >97% Coulombic efficiency, whereas the Daramic membrane withstands only 200 cycles due to severe water transport from the catholyte to the anolyte. The zinc bromine redox flow battery assembled with the MWCNT/PAN composite Daramic membrane significantly reduces the self-discharge rate and retains an open circuit voltage of 1.69 V for 13.40 h in comparison to the Daramic membrane (10.83 h) and the PAN composite membrane (11.13 h). Thus, the extraordinary flow cell performance and stability of the MWCNT/PAN composite Daramic membrane lead to the development of an alternative to the microporous Daramic membrane in zinc bromine redox flow batteries.

Interaction between Filler and Polymeric Matrix in Nanocomposites: Magnetic Approach and Applications

In recent years, polymer nanocomposites produced by combining nanofillers and a polymeric matrix are emerging as interesting materials. Polymeric composites have a wide range of applications due to the outstanding and enhanced properties that are obtained thanks to the introduction of nanoparticles. Therefore, understanding the filler-matrix relationship is an important factor in the continued growth of this scientific area and the development of new materials with desired properties and specific applications. Due to their performance in response to a magnetic field magnetic nanocomposites represent an important class of functional nanocomposites. Due to their properties, magnetic nanocomposites have found numerous applications in biomedical applications such as drug delivery, theranostics, etc. This article aims to provide an overview of the filler-polymeric matrix relationship, with a special focus on magnetic nanocomposites and their potential applications in the biomedical field.

Tunable Multilevel Data Storage Bioresistive Random Access Memory Device Based on Egg Albumen and Carbon Nanotubes

In this paper, a tuneable multilevel data storage bioresistive memory device is prepared from a composite of multiwalled carbon nanotubes (MWCNTs) and egg albumen (EA). By changing the concentration of MWCNTs incorporated into the egg albumen film, the switching current ratio of aluminium/egg albumen:multiwalled carbon nanotubes/indium tin oxide (Al/EA:MWCNT/ITO) for resistive random access memory increases as the concentration of MWCNTs decreases. The device can achieve continuous bipolar switching that is repeated 100 times per cell with stable resistance for 104 s and a clear storage window under 2.5 × 104 continuous pulses. Changing the current limit of the device to obtain low-state resistance values of different states achieves multivalue storage. The mechanism of conduction can be explained by the oxygen vacancies and the smaller number of iron atoms that are working together to form and fracture conductive filaments. The device is nonvolatile and stable for use in rewritable memory due to the adjustable switch ratio, adjustable voltage, and nanometre size, and it can be integrated into circuits with different power consumption requirements. Therefore, it has broad application prospects in the fields of data storage and neural networks.

Electrochemical Biosensing of Dopamine Neurotransmitter: A Review

Neurotransmitters are biochemical molecules that transmit a signal from a neuron across the synapse to a target cell, thus being essential to the function of the central and peripheral nervous system. Dopamine is one of the most important catecholamine neurotransmitters since it is involved in many functions of the human central nervous system, including motor control, reward, or reinforcement. It is of utmost importance to quantify the amount of dopamine since abnormal levels can cause a variety of medical and behavioral problems. For instance, Parkinson's disease is partially caused by the death of dopamine-secreting neurons. To date, various methods have been developed to measure dopamine levels, and electrochemical biosensing seems to be the most viable due to its robustness, selectivity, sensitivity, and the possibility to achieve real-time measurements. Even if the electrochemical detection is not facile due to the presence of electroactive interfering species with similar redox potentials in real biological samples, numerous strategies have been employed to resolve this issue. The objective of this paper is to review the materials (metals and metal oxides, carbon materials, polymers) that are frequently used for the electrochemical biosensing of dopamine and point out their respective advantages and drawbacks. Different types of dopamine biosensors, including (micro)electrodes, biosensing platforms, or field-effect transistors, are also described.

Magnetic Properties Study of Iron Oxide Nanoparticles-Loaded Poly(ε-caprolactone) Nanofibres

Magnetic nanofibres have attracted more and more attention recently due to their possible applications e.g., in spintronics and neuromorphic computing. This work presents the synthesis and physicochemical characterization of the electrospun nanofibres of poly(ε-caprolactone) (PCL) doped by iron oxide nanoparticles with diameters of 5 nm. PCL is a semi-crystalline, hydrophilic polymer showing controllable biodegradation rates, biocompatibility, and flexible mechanical properties. In the composite material, two different concentrations of magnetic nanoparticles were used: 2 and 6 wt.%. PCL-based composites were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry (TGA). Although in the literature one can find many studies on magnetic polymeric composites, the investigation of their magnetic properties is usually limited to measuring the magnetization curve. Detailed analysis of dynamic magnetic susceptibility is rather rare. In this report, special attention was paid to the detailed analysis of magnetic properties, where we followed the evolution of changes in the magnetic behavior of the material depending on the concentration of magnetic nanoparticles.

Hollow cellulose-carbon nanotubes composite beads with aligned porous structure for fast methylene blue adsorption

Polysaccharide based beads with unique porous structure have gained considerable interests due to their specific adsorption behaviors and biodegradability. The purpose of this paper was to develop hollow cellulose/carbon nanotubes composite beads with aligned porous structure which have potential applications in fast adsorption field. The composite beads were fabricated by ice template and freeze-drying technology. Different characterizations have proved that the carbon nanotubes and magnetic nanoparticles have been incorporated into the cellulose beads. Higher concentration of carbon nanotubes and cellulose would result in a larger diameter of the composite beads. The composite beads can effectively adsorb the methylene blue (MB). The pseudo-second-order model and Langmuir isotherm were best fitted to the adsorption. The composite beads showed a fast adsorption behavior towards MB with a t_1/2 of 1.07 min obtained from pseudo-second-order model. The maximum adsorption capacity was 285.71 mg g^-1 at pH 7.0. The composite beads also showed good reusability and biodegradability. We anticipate that different polysaccharides based composite beads with aligned porous structure can be obtained through the similar methods and applied in adsorption fields.

Fabrication, Functionalization, and Application of Carbon Nanotube-Reinforced Polymer Composite: An Overview

A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. This is evidence that the development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. As a promising material with a wide range of applications, their poor solubility in aqueous and organic solvents has hindered the utilizations of CNTs. The current state of research in CNTs-both single-wall carbon nanotubes (SWCNT) and multiwalled carbon nanotube (MWCNT)-reinforced polymer composites-was reviewed in the context of the presently employed covalent and non-covalent functionalization. As such, this overview intends to provide a critical assessment of a surging class of composite materials and unveil the successful development associated with CNT-incorporated polymer composites. The mechanisms related to the mechanical, thermal, and electrical performance of CNT-reinforced polymer composites is also discussed. It is vital to understand how the addition of CNTs in a polymer composite alters the microstructure at the micro- and nano-scale, as well as how these modifications influence overall structural behavior, not only in its as fabricated form but also its functionalization techniques. The technological superiority gained with CNT addition to polymer composites may be advantageous, but scientific values are here to be critically explored for reliable, sustainable, and structural reliability in different industrial needs.

Electronic structure of polypyrrole composited with a low percentage of graphene nanofiller

The low concentration of graphene (<5%) in graphene/polypyrrole composites makes it quite challenging to devise a theoretical model for these composites. Thus, herein, we present theoretical calculations to determine the geometric electronic and optical properties of graphene/polypyrrole composites. Ribbon and sheet models of various sizes were considered for graphene. Oligopyrrole of various lengths was deposited in the graphene model in different orientations including π-stacking, tilted and vertical orientations. Theoretical calculations at the M062X/def2-SVP level revealed that π-stacking is the preferred orientation. To model a lower concentration of graphene, sandwich complexes of oligopyrrole were considered with graphene nanoribbons. Interaction energies revealed that sandwich complexes possessed superior additivity. The NCI analysis established that weak van der Waals interactions existed in all composites. Moreover, the HOMO-LUMO gap decreases as the concentration of graphene increases. Thus, the computed optical band gap of the C₅₈H₂₄-based composite is about 1.7 eV, which is consistent with the reported experimental value (2.1-1.81 eV). The computed band gap further decreases to ∼1.6 eV when the proportion of graphene increases to C₆₄H₂₆. Thus, our results for the graphene nanoribbon-based polypyrrole composites are in good agreement with experimental results. The UV/visible spectra revealed that as the concentration of graphene increases, a red shift is observed for all the configurations, which is consistent with experimental results.

Carbon Nanomaterials Embedded in Conductive Polymers: A State of the Art

Carbon nanomaterials are at the forefront of the newest technologies of the third millennium, and together with conductive polymers, represent a vast area of indispensable knowledge for developing the devices of tomorrow. This review focusses on the most recent advances in the field of conductive nanotechnology, which combines the properties of carbon nanomaterials with conjugated polymers. Hybrid materials resulting from the embedding of carbon nanotubes, carbon dots and graphene derivatives are taken into consideration and fully explored, with discussion of the most recent literature. An introduction into the three most widely used conductive polymers and a final section about the most recent biological results obtained using carbon nanotube hybrids will complete this overview of these innovative and beyond belief materials.

Functional Polymer Hybrid Nanocomposites Based on Polyolefins: A Review

For the last twenty years, polymer hybrid nanocomposites have enjoyed unflagging interest from numerous scientific groups and R&D departments, as they provide notable enhancement of properties, even at low nanofillers’ content. Their performance results from many factors, the most important of which is the uniform distribution in the entire volume of the matrix, that still is very challenging, but is the right choice of two types of nanoparticles that can lead to an increase of dispersion stability and even more uniform distribution of fillers. The incorporation of two types of nanofillers, especially when they differ in aspect ratio or chemical nature, allows to additively reduce the price of the final composite by replacing the more expensive filler with the cheaper one, or even synergistically improving the properties, e.g., mechanical, thermal, and barrier, etc., that can extend their usage in the industry. Despite numerous review papers on nanocomposites, there is no review on how the introduction of a hybrid system of nanofillers affects the properties of polyolefins, which are the most commonly used engineering plastics. This review deeply focuses on the structure–properties relationship of polyolefins-based hybrid nanocomposites, especially based on two types of polyethylenes (low-density polyethylenes (LDPE) and high-density polyethylenes (HDPE)) and polypropylene.