Carboxylated Carbon Nanotubes Research Articles

Touch–based potentiometric sensors for simultaneous detection of urea and ammonium from fingertip sweat

Urea is a biomarker for diagnosis and management of multiple disorders. The measurement of urea could help in the diagnosis of patients with kidney dysfunction. Despite their attractive analytical performances, the existing urea measurement methods are still limited to sophisticated and time–consuming or require invasive blood sampling. Herein, a reliable noninvasive, simple, and disposable touch–based potentiometric sensor is fabricated for rapid monitoring of fingertip sweat urea. Novel touch–based urea detection relies on immobilized urease recognition and a solid–contact ammonium–ion–selective electrode, along with a screen–printed carbon working electrode modified carboxylated carbon nanotubes for enhancing sensor’s sensitivity. The fingertip sweat under sedentary rest conditions can be instantaneously collected on customized porous polyvinyl alcohol hydrogel transporting sweat to working electrode surface where the hydrolysis of urea is catalyzed, generating bicarbonate and ammonium. The resulting ammonium can be detected with ion–selective transducer, enabling indirect monitoring of sweat urea. Potential interference from co–existing ammonium in human sweat is addressed by developing a dual disposable potentiometric sensor, consisting of urea and ammonium sensors on a single strip platform allowing for simultaneous touch–based detection of sweat urea and ammonium. The resulting dual disposable sensing system offers rapid urea and ammonium monitoring within a group of healthy human subjects, along with a good correlation with R2 = 0.974 between the sweat urea and capillary blood urea levels. Additional confirmation among a broad sample of individuals along with the validation of sensor data through centralized laboratory tests will establish the practicality of simultaneously monitoring urea and ammonium levels.

Ultrasensitive electrochemical detection of bile acids via ZIF-67-MOF-derived CoNi(OH)x/CeO2/COOH-MWCNTs composite electrodes

Fast and ultra-sensitive assays are essential for the assessment of the efficacy of traditional Chinese medicines. Here, an ultrasensitive and rapid electrochemical detection of bile acid in traditional Chinese medicine using composite electrodes is presented. Cobalt-nickel hydroxide and cerium dioxide (CoNi(OH)x/CeO2) nanomaterials were synthesized in situ by a two-step reflux method with cobalt-containing metal–organic framework (ZIF-67), as precursor. It was ultrasonically complexed with carboxylated carbon nanotubes (COOH-MWCNTs) to form CoNi(OH)x/CeO2/COOH-MWCNTs composites, for facile direct detection of bile acids in traditional Chinese medicine. Characterization methods were used to verify the successful creation of the composite CoNi(OH)x/CeO2/COOH-MWCNTs, a material which demonstrated excellent electrochemical properties. The experimental results showed that the electrode responded well when bile acids, nicotinamide adenine dinucleotide, and 3α hydroxysteroid dehydrogenase were simultaneously present in the solution, and that the peak current had a good linear relationship (R2 = 0.988) with the concentration of bile acids (0.05–10.0 µM). The sensor has an outstanding detection limit of 1.0 nM, 2–3 orders of magnitude more sensitive than the concentration. Therefore, it can be used for rapid on-site detection of bile acids in real traditional Chinese medicines.

3D porous conductive matrix based on phase-transited BSA and covalent coupling-stabilized transition ZnS-CNT for antifouling and on-site detection of nitrite in soil

Nitrite plays a critical role in a variety of nitrification and denitrification processes in the nitrogen cycle. Due to the high surface energy, tendency to aggregate, and poor conductivity, current nitrite ZnS-based sensing platform could not meet the need of on-site nitrite detection in smart agriculture. In order to address these issues, the carboxylated carbon nanotube (CNT) was introduced to reduce the surface energy and prevented aggregation of ZnS, while ZnS-carboxylated CNT (ZnS-CNT) composite also provided excellent electrochemical conductivity. Furthermore, the introduction of phase transition BSA (PTB) created a three-dimensional porous conductive matrix without interfering with the mass transfer process of nitrite. The resulting sensing platform exhibited a linear detection range of 10 nM to 0.4 mM for nitrite, with a detection limit of 0.73 nM. And this sensing platform had the excellent antifouling ability to direct detection nitrite in real soil suspension. In addition, the sensing platform demonstrated remarkable resistance to interferences from pH variations, microbial presence, and organic pollutants that usually present in soil environment. Therefore, on-site detection of nitrite ions in soil environment was realized no needing complex pretreatments.

Ultrastrong and Reusable Solar‒Thermal‒Electric Generators by Economical Starch Vitrimers.

In frigid regions, it is imperative to possess functionality materials that are ultrastrong, reusable, and economical, providing self-generated heat and electricity. One promising solution is a solar‒thermal‒electric (STE) generator, composed of solar‒thermal conversion phase change composites (PCCs) and temperature-difference power-generation-sheets. However, the existing PCCs face challenges with conflicting requirements for solar‒thermal conversion efficiency and mechanical robustness, mainly due to monotonous functionalized aerogel framework. Herein, a novel starch vitrimer aerogel is proposed that incorporates orientational distributed carboxylated carbon nanotubes (CCNT) to create PCC. This innovative design integrates large through-holes, mechanical robustness, and superior solar‒thermal conversion. Remarkably, PCC with only 0.8 wt.% CCNT loading achieves 85.8MPa compressive strength, 102.4°C at 200mW cm-2 irradiation with an impressive 92.9% solar-thermal conversion efficiency. Noteworthy, the STE generator assembled with PCC harvests 99.1W m-2 output power density, surpassing other reported STE generators. Strikingly, even under harsh conditions of -10°C and 10mW cm‒2 irradiation, the STE generator maintains 20°C for PCC with 325mV output voltage and 45mA current, showcasing enhanced electricity generation in colder environments. This study introduces a groundbreaking STE generator, paving the way for self-sufficient heat and electricity supply in cold regions.

Effect of functionalized carbon nanotube on cement mortar: From experiment to DFT research

In this paper, functionalized nanotube-reinforced cementitious composites were prepared, and the mechanical property test results showed that the 28d flexural strength of the composite was increased by 41.58% at a hydroxylated carbon nanotube mass fraction of 0.08[Formula: see text]wt.% compared to the original cement mortar. Carboxylated carbon nanotubes with a mass fraction of 0.02%, on the other hand, increased the 28d compressive strength by 99.12%. Probing the effect of the presence of functional groups on carbon nanotubes on the CNT/C–S–H interface by first principles. The results showed that the shear strengths (11.392[Formula: see text]MPa and 14.130[Formula: see text]MPa) of hydroxylated carbon nanotubes and plain carbon nanotubes at the interface with cementitious (CNT-OH/CSH and CNT/CSH) were lower than the shear strengths (21.584[Formula: see text]MPa) of carboxylated carbon nanotubes at the interface with cementitious (CNT-COOH/CSH). The adsorption of functional groups on carbon nanotubes changes the electron distribution on the surface of carbon nanotubes. The introduction of carboxyl groups exacerbates the charge transfer between carbon nanotubes and cementitious groups and promotes the generation of solid chemical bonds. This is the reason that carboxylated nanotubes added as reinforcement to cement mortar give better strength to the composite than hydroxylated nanotubes.

Self-Healing and Self-Adhesion Conductive Hydrogels Reinforced by Carboxylated Carbon Nanotubes for High-Performance Wearable Strain Sensors

Self-Healing and Self-Adhesion Conductive Hydrogels Reinforced by Carboxylated Carbon Nanotubes for High-Performance Wearable Strain Sensors

Affinity-based engineering of carbon nanotube embedded polyamide membranes for simultaneous desalination and boron removal

Reverse osmosis (RO) is the leading technology for obtaining drinking and irrigation water from seawater. Although currently developed RO membranes achieve high salt rejection; several challenges exist, such as permselectivity trade-off, biological/chemical contamination, and insufficient retention of small and neutral molecules like boric acid. Due to its toxicity to living organisms and strictly monitored levels in potable water, removal of boron has gained considerable attention in RO industry. Thin film nanocomposite (TFN) membranes have emerged by incorporating nanomaterials with superior water/salt selectivity into polyamide (PA) layer of composite membranes. For the first time, our group investigated the potential of carboxylated carbon nanotube (CNT) embedding in the selective layer of TFN membranes for boron removal. Within this frame, we hypothesize that embedding fillers with low boron affinity accompanied by high water permeability in the selective layer of TFN membranes improves boron removal without suffering from the permselectivity trade-off. In this study, we investigated the boron removal performance of functionalized CNT (f-CNT) embedded TFN membranes. Initially, CNTs were functionalized with three different functional groups (namely, biotin (BIO), 8-amino caprylic acid (ACA), and zwitterion (ZWT)) to narrow down the tube entrance, provide repulsive electrostatic interactions with boron, and interfere with the hydrogen bonding between water and boric acid molecules. Then, TFN membranes incorporating f-CNTs were fabricated, characterized, and tested. Showing high compatibility with PA, ZWT functionalization has increased water/boron selectivity of TFN membranes by 66% and water permeability by 44%, while maintaining the salt rejection at 98%. Furthermore, we employed molecular dynamics simulations and potential of mean force calculations to elucidate the boron exclusion mechanism in f-CNTs. With its flexible structure and “gate-keeper” ability, ZWT functional group was found to show the highest energy barrier against boron transport. Hence, engineering CNT/PA TFN membranes to promote steric hindrance and decrease solute affinity is promising for efficient removal of detrimental small molecules from seawater.

Synthesis, characterization and application of tangerine peel-derived Fe3C/Fe-encapsulated biochar for electrochemical removal of environmental pollutant

Conforming to the principles of green chemistry and sustainable environmental progress, this work demonstrated the concept of “treating waste with waste”, i.e. treating atmospheric pollutant sulfur dioxide (SO2) with agricultural waste of tangerine peel. SO2 electro-catalytic oxidation is the key technique in this endeavor, which utilizes SO2 as reaction raw material in the anode to remove it. The anodic SO2 electro-catalytic oxidation could be coupled to the cathodic hydrogen evolution to achieve the simultaneous SO2 removal and hydrogen production. Anodic catalyst plays a vital role in this SO2 transformation. In this work, tangerine peel has been re-utilized to afford tangerine peel-derived biochar (TPB) to prepare TPB/CNT-derived Fe3C/Fe/C (N-doped) as a capable anodic catalyst to achieve this goal. With help of various characterization techniques and electrochemical testing, the optimal iron mass fraction and pyrolysis temperature were found to be 16 wt% Fe under 800 °C, with carboxylated carbon nanotube as carbon additive. Transmission electron microscopy (TEM) image showed that the as-prepared TPB/CNT-derived Fe3C/Fe/C (N-doped) featured a unique morphology to encapsulate Fe3C/Fe with a layer of protecting carbon, which should contribute to the enhanced electro-catalytic performances. A flow electrolyzer was also assembled to illustrate practical application of the anodic catalyst in the real scenario. Owing to its lower cost, the as-prepared TPB/CNT-derived Fe3C/Fe/C (N-doped) will be advantageous to replace precious metals to mediate SO2 electro-catalytic oxidation as one of promising environmental treatment techniques in the future.

Dual–network carboxymethyl chitosan conductive hydrogels for multifunctional sensors and high–performance triboelectric nanogenerators

With the development of technology, there is a growing demand for wearable electronics that can fulfill different application scenarios. Hydrogel–based sensors are considered ideal candidates for realizing multifunctional wearable flexible devices. However, there are great challenges in preparing hydrogel–based sensors with both superior mechanical and electrical properties. Herein, we report a composite conductive hydrogel prepared by using a dynamically crosslinked carboxymethyl chitosan network and a covalently crosslinked polymer network, and carboxylated carbon nanotubes as conductive filler. The carboxymethyl chitosan–based hydrogels had excellent mechanical properties and strength (tensile strength of 475.4 kPa, and compressive strength of 1.9 MPa) and ultra–high conductivity (0.19 S·cm−1). Based on the above characteristics, the hydrogel could accurately identify the movement signals of the human body and different writing signals, and achieve encrypted transmission of signals, broadening the application scenarios. In addition, a triboelectric nanogenerator (TENG) was fabricated based on the hydrogel, which had an outstanding output performance with open–circuit voltage of 336 V, short–circuit current of 18 μA, transferred charge of 52 nC and maximum power density of 340 mW·m−2, and could power small devices. This work is expected to provide new ideas for the development of self–powered, multi–functional wearable, and flexible polysaccharide–based devices.

Enhanced rheological properties of carbon nanotubes reinforced natural rubber/butadiene rubber nanocomposites

AbstractEffects of carbon nanotubes (CNTs) content and the in situ surface modification via bis(triethoxysilylpropyl) disulfide (Si75) and (3‐aminopropyl) triethoxysilane (KH550) on the rheological properties of rubber nanocomposites are explored. Results from the strain sweep demonstrate that the filler network of the nanocomposite is enhanced when the hydroxylated CNT (HCNT) is incorporated. The promotion of filler–rubber interaction in nanocomposite reinforced with modified CNT is validated by both stress relaxation and strain sweep measurements. The die swell ratio (B) declines with increasing HCNT content and rises with a heightened shear rate. Compared to those without HCNT, B of the nanocomposites, which contained 5 phr HCNT, decreased by 5.4%, 7.0%, and 17.3% at 50, 200, and 500 s−1, respectively. The Si75‐modified HCNT and the carboxylated CNT (CCNT) reduce the B‐value of the extrudates at 500 s−1 by 3.7% and 3.0%, respectively. However, the extrudates filled with KH550‐modified HCNT or CCNT showed a larger B due to pre‐crosslinking, as demonstrated by stress relaxation and swelling tests. Furthermore, it is also found that the application of KH550 has an acceleration effect on the curing reaction, increasing the curing efficiency by 8.5%.Highlights The promotion of filler–rubber interaction is validated by RPA. The dimensional stability of the composites is improved after incorporating CNT. The extrudates with Si75 exhibit a reduced B and improved surface morphology. CNT content increase raises MH, ML, and shortens the t10 of the composite.

The orchestration of sustained drug delivery by bacterial cellulose/gelatin nanocomposites reinforced with carboxylic carbon nanotubes

Recently, modifying bacterial cellulose (BC) by compositing it with other nano-biomaterials has become inevitable to achieve its desired properties in drug delivery. To address this, our study endeavors to utilize an in-situ fabrication method for the creation of a multifunctional BC/gelatin (BC/Gel) platform reinforced with carboxylic multi-walled carbon nanotubes (cMWCNTs) as a sustainable delivery model of biomolecules. Incipiently, cMWCNTs were loaded with human serum albumin (HSA) as a drug model, with an optimized nanoparticle-to-protein ratio of 1:5 and loading efficiency of 90.0 ± 1.0 % before incorporation into BC/Gel hydrogels. By comparison, nanocomposition improved the surface area and overall porosity of BC/Gel up to 58.0 ± 1.3 m2/g and 85.5 ± 1.1 %, respectively. Likewise, significant wettability of 44.0 ± 0.1° and dramatic biodegradation rate of 36.9 ± 1.2 % were other exceptionally gained attributes. Meanwhile, with a Zero-order kinetic mechanism, CNT-HSA integration facilitated the controlled release of 56.0 ± 0.9 % HSA over 7 days. Drug-loaded nanocomposites showcased >70 % viability during in vitro cellular trials using Human Foreskin Fibroblasts (HFF). Overall, BC/Gel/CNT-HSA nanocomposite exhibited favorable cell behavior, devoid of cytotoxic manifestations. Consequently, this BC-based nanocomposite scaffold implicates the premiere capability in the sustained delivery of an extended range of protein biomolecules, offering a promising therapeutic avenue for bolstering tissue regeneration.

Relationship between the aging thermal oxygen and mechanical properties of nitrile butadiene rubber reinforced by RD-loaded carboxylated carbon nanotubes

A novel functional carbon nanofiller CNTs-COOH-RD resistant to thermal-oxidative aging was prepared by grafting 1,2-dihydro-2,2,4-trimethyl-quinoline (antioxidant RD) onto the surface of carboxylated carbon nanotubes (CNTs-COOH) using γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560). Five groups of nitrile butadiene rubber (NBR) composites were prepared by mechanical blending, and the effects of CNTs-COOH-RD on the mechanical and tribological properties of NBR composites were investigated. The results showed that compared to pure NBR and free antioxidant RD-loaded samples, the tensile and tear strengths increased by approximately 23%, 5%, 18%, and 4%, respectively. The wear surfaces of the NBR composites were characterized using scanning electron microscopy and X-ray energy spectroscopy, which revealed the reinforcing mechanism of CNTs-COOH-RD. Molecular dynamics simulations were used to explain the thermal-oxidative aging mechanism of CNTs-COOH-RD from an atomic mechanism perspective. The results showed that the mobility of CNTs-COOH-RD within the NBR matrix was significantly reduced compared with that of the free antioxidant RD. The proposed functional carbon nanofiller enabled the NBR composites to exhibit superior mechanical and thermal-oxidative aging properties during the aging failure process.

Unravelling pH/pKa influence on pH-responsive drug carriers: Insights from ibuprofen-silica interactions and comparative analysis with carbon nanotubes, sulfasalazine, and alendronate

This study employs density functional theory to explore the interaction between ibuprofen (IBU) and silica, emphasizing the influence of the trimethylsilyl (TMS) functional group for designing pH-responsive drug carriers. The surface (S) and drug (D) molecules' neutral (0) or deprotonated (−1) states were taken into consideration during the investigation. The likelihood of these states was determined based on the pKa values and the desired pH conditions. To calculate the pH-dependent interaction energy (EintpH), four different situations have been identified: S0D0, S0D−1, S−1D0, and S−1D−1.The electrostatic component of interaction energy aligns favorably with its theoretical value in both the Debye-Hückel and Grahame models. The investigation has gathered first-hand experimental data on the drug loading and release of pH-responsive mesoporous silica nanoparticles. Effective drug loading was observed in the acidic environment of the stomach (pH 2–5), followed by a release in the slightly basic to neutral pH of the small intestine (pH 7.4), These findings align with existing literature. The results revealed horizontal drug adherence on silica surfaces, improving binding capabilities. Comparisons were made with combinations involving carboxylated carbon nanotubes and ibuprofen, silica, and sulfasalazine, and silica and alendronate, exploring drug loading/release dynamics associated with positive/negative interaction energies. The investigation, supported by experimental data, contributes valuable insights into pH-responsive mesoporous silica nanoparticles, offering new design possibilities for drug carriers.

Molecular dynamics study of the mechanical properties of hydrated calcium silicate enhanced by functionalized carbon nanotubes.

The incorporation of functionalized carbon nanotubes can enhance the mechanical properties of cement-based materials. However, the types of functional groups and their roles in composite materials are not yet clear. In this study, molecular dynamics (MD) simulation methods were employed to investigate the mechanical performance of hybridized calcium silicate hydrate gel reinforced with pure carbon nanotubes, epoxy-coated carbon nanotubes, carboxylated carbon nanotubes, and hydroxylated carbon nanotubes. The results indicate that the addition of all four types of nanotubes can enhance the mechanical properties of hydrated calcium silicate gel compared to pure C-S-H. Tensile loading results show that carbon nanotubes can act as bridges for microcracks in the composite material, and functionalized nanotubes exhibit a better reinforcing effect than pure carbon nanotubes. Under tensile stress, hydroxylated nanotubes are more effective in increasing the toughness of the composite material, while carboxylated nanotubes tend to enhance the strength of the composite material. The compressive loading results indicate that the compressive strength of cement-based materials is higher than their tensile strength. Overall, carboxylated nanotubes show particularly remarkable performance in enhancing the mechanical properties of cement-based materials. Compared to pure C-S-H gel, the tensile and compressive elastic moduli of carboxylated nanotube/C-S-H composite material increased by 18.13% and 34.78%, respectively. Its tensile and compressive strengths also increased by 30.40% and 40.23%, respectively. All molecular dynamics simulations were performed on the classical computational simulation platform LAMMPS. In this paper, the parameters in the ClayFF force field are chosen to simulate calcium hydrated silicate (/C-S-H), and the ClayFF-CVFF combined force field is used to simulate the mechanical properties of the CNT/C-S-H molecular model structure.

Highly stretchable, environmentally stable, self-healing and adhesive conductive nanocomposite organohydrogel for efficient multimodal sensing

Conductive hydrogel (CH) has drawn widespread interest in flexible electronics, human–computer interaction, and electronic skins (e-skins). However, it is challenging to integrate satisfactory self-adhesion, self-healing, environmental stability, and multi-stimulus response into a single CH system. Herein, a conductive nanocomposite organohydrogel with the above characteristics is well-designed and developed via incorporating carboxylic cellulose nanofibers-carrying carboxylic carbon nanotubes (C-CNTs) and phytic acid (PA) into polyacrylamide network through free-radical polymerization plus glycerol solvent displacement strategy, aiming for a high-performance multimodal sensing platform. Here, the coupling of C-CNTs and ionization of PA contributes a favorable conductivity, and the coexistence of glycerol and PA is beneficial for the formation of amounts of hydrogen bonds that endow the organohydrogel with outstanding stretchability, self-healing, and favorable adhesion in a wide temperature range of −30 to 60 °C. Besides, the resultant organohydrogel can effectively detect multiple external stimuli, manifesting high strain sensitivity over a broad strain range (0–1566 %), good humidity detectability at 0–85 % RH, and reliable thermosensation capability over a wide temperature window (−30 to 60 °C). Significantly, the application of the organohydrogel as e-skins are conducted to detect full-range human activity movements even in the extreme environments, identify hand gestures, and recognize the spatial distribution of humidity in noncontact sensing. All these indicate the preponderance of our organohydrogel in the fields of flexible smart electronics.

Synergistic enhancement of the robustness of multifunctional polyurethane via an ionic noncovalent cross-linking network and aromatic disulfides

The preparation of functional polyurethane materials with high strength, toughness, and excellent self-healing ability is currently challenging. In this study, a multifunctional bi-dynamic supramolecular crosslinked network PU elastomer was successfully prepared by introducing ionic bonds and aromatic disulfide bonds into a PU matrix. The resulting ionic PU elastomers exhibited impressive mechanical properties, including high tensile strength (39.9 ± 4.4 MPa) and excellent elongation at break (1930 ± 345 %). They also demonstrated efficient self-healing capability (94.4 %), recyclability and processability. The distribution of hydrophilic ion bonds within the polymer networks enabled the elastomers to possess water-induced shape memory and antibacterial activity. Additionally, the hydrophilicity of the elastomers provided a self-cleaning ability when used as a coating material. The covalent bonding of the cations with the PU matrix prevented the leaching of bactericidal substances, ensuring good biocompatibility of the ionic PU. Furthermore, a double-layered self-healing composite flexible sensor was developed using the ionic PU as the substrate and carboxylated carbon nanotubes (CNTs-COOH) as the conductive medium to detect human motion. These multifunctional ionic PU elastomers offer great potential for the design and preparation of robust materials with self-healing ability for various applications across multiple fields.

The effect of chemical etching and nanostructure additive epoxy coating technique on adhesion strength in aluminum joints bonded with nanostructure additive adhesive

In the present study, in order to increase the strength of adhesively bonded joints, the surface of the adherend was chemically etched with an anodizing treatment process at different temperatures and the surface was coated with nanostructure doped epoxy. Additionally, carbon nanostructures were added to the adhesive at different ratios to increase the strength of both the adhesive and the joint. In the study, in order to clean the surfaces of AA2024-T3 aluminum alloy plates and eliminate the oxide layer, the plates were chemically treated with a sodium hydroxide solution. Afterwards, the surfaces of these aluminum alloy plates were chemically etched with an anodizing treatment process at temperatures of 25, 40 and 60 °C. The aim here is to create different surface roughness and surface energy on the aluminum alloy surface. Epoxy pre-coating (EPC) was applied to the chemically etched aluminum alloy surfaces. Furthermore, a single-lap joint was produced by adding 0.5 %, 1 % and 2 % carboxylated carbon nanotube (CNT-COOH) by weight to the EPC and adhesive applied to the surfaces and the failure loads of the joints were examined. As a result, when the failure load obtained from the experiments was examined, it was found that chemical etching alone increased the joint strength by 22 % while the chemical etching and EPC application increased it by 46 %, the chemical etching and nanostructure doped EPC application increased it by 61 % and nanostructure addition to the adhesive increased it by 93 %. However, these increases in joint strength vary depending on the duration of the anodizing treatment process and the nanostructure additive ratio. In the chemical analyses performed to interpret these results, surface roughness test, surface contact angle test, X-ray photoelectron spectroscopy (XPS), fourier-transform-infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and images obtained from the failure surfaces were used, respectively.

Electrocatalysts composed of amorphous red phosphorous nanosheets coupled with carboxylic group carbon nanotubes for Li[sbnd]S batteries

The large-scale applications of lithium sulfur batteries have been limited by their rapid capacity loss, which can be attributed to the dissolution of polysulfide intermediates and subsequent irreversible shuttling effect. Several strategies have been attempted to the solve these problems by designing novel cell structure, including the modification of separator. Herein, a hybrid is obtained via a ball-milling with red phosphorous and carboxylic group carbon nanotubes (CNTs), in which bulk red phosphorous are simultaneous grounded into an overview of red phosphorous nanosheets (NP) and distribution the hybrid. Moreover, the P-O-C and PC chemical bonds are formed between red phosphorous and CNTs upon ball-milling, which enable an intimate and robust contact between red phosphorous and CNTs, and thus facilitates the electron transfer and enhances the surface polarity of NP@CNTs. The red phosphorous nanosheets also possess a strong affinity to sulfur species, which could effectively adsorb lithium polysulfides, and boost their redox reaction catalytically-accelerate the reversible soluble/insoluble phases conversion. Benefiting from this unique nanostructures, the lithium‑sulfur (LiS) cell based on NP@CNTs hybrid modified separator has an initial discharge capacity of 895.8 mAh g−1 at 0.3C and sustain a capacity of 704.2 mAh g−1 after 300 cycles, corresponding to a retention rate of 78.6 %. The cell with a high sulfur loading of 8.9 mg cm−2, it shows a discharge capacity of 7.6 mAh cm−2 and still maintains 6.5 mAh cm−2 over 100 cycles.

Novel bone cement based on calcium phosphate composited CNT curcumin with improved strength and antitumor properties.

In this study, carboxylated carbon nanotube (CNT)-loaded curcumin (CUR) was blended into calcium phosphate cement (CPC) owing to the poor mechanical properties and single function of CPC as a bone-filling material, and CNT-CUR-CPC with improved strength and antitumor properties was obtained. The failure strength, hydrophilicity, in vitro bioactivity, bacteriostatic activity, antitumor activity, and cell safety of CNT-CUR-CPC were evaluated. The experimental results indicated that the failure strength of CNT-CUR-CPC increased from 25.05 to 45.05 MPa (p < 0.001) and its contact angle decreased from 20.37° to 15.27° (p < 0.001) after the CNT-CUR complex was added into CPC at the rate of 5 wt% and blended. Following soaking in simulated body fluid (m-SBF), the main components of CNT-CUR-CPC were hydroxyapatite (HA) and carbonate hydroxyapatite (HCA). The incorporation of CNT-CUR was beneficial for the deposition of PO43- and CO32-, and it promoted the crystallization of HA and HCA. For CNT-CUR-CPC, the inhibition zone diameter on Staphylococcus aureus was 10.2 ± 1.02 mm (p < 0.001) and it exhibited moderate sensitivity, whereas the inhibition zone diameter on Escherichia coli was 8.3 ± 0.23 mm (p < 0.001) and it exhibited low sensitivity. When compared with the CPC, the cell proliferation rate (RGR %) of the CNT-CUR-CPC decreased by 7.73% (p > 0.05) at 24 h, 17.89% (p < 0.05) at 48 h, and 24.43% (p < 0.001) at 72 h when MG63 cells were cultured on it. In particular, after the MG63 cells were cultured with the CNT-CUR-CPC for 48 h, the number of newly proliferating MG63 cells was significantly reduced, and their growth and adhesion on the surface of the CNT-CUR-CPC were inhibited when compared with the CPC. When 3T3-E1 cells were exposed to the m-SBF immersion solution of CNT-CUR-CPC, the cell proliferation rate (RGR %) was ≥80% (p > 0.05) and the cytotoxicity grade was 0-1. The 3T3-E1 cells were cultured with the m-SBF soaking solution of CNT-CUR-CPC for 24 h, and no significant changes in cell morphology or cytotoxicity were observed. After the 3T3-E1 cells were cultured on CNT-CUR-CPC for 48 h, they could stick to and grow on its surface without adverse reactions. CNT-CUR-CPC had a hemolysis rate of 4.3% (p > 0.05) and did not result in hemolysis and hemagglutination. The obtained CNT-CUR-CPC scaffold material exhibited effective antibacterial activity and cell safety, and could achieve a certain antitumor effect, which has a wide application potential in bone tissue engineering.

Noninvasive glucose monitoring using portable GOx-Based biosensing system

Wearable biosensors have gained huge interest due to their potential for real-time physiological information. The development of a non-invasive blood glucose device is of great interests for health monitoring in reducing the diabetes incidence. Here, we report a sandwich-structured biosensor that is designed for glucose levels detection by using sweat as the means of monitoring. The Prussian blue nanoparticles (PBNPs) and carboxylated carbon nanotubes (MWCNT-COOH) were self-assembled on the electrode to improve the electrochemical performance and as the sensor unit, glucose oxidase (GOx) was immobilized by chitosan (CS) as the reaction catalysis unit, and finally encapsulated with Nafion to ensure a stable performance. As a result, the GOx/PBNPs/MWCNT-COOH sensor displays a low detection limit (7.0 μM), high sensitivity (11.87 μA mM−1 cm−2), and excellent interference resistance for a full sweat glucose application range (0.0–1.0 mM) for both healthy individuals and diabetic patients. Additionally, the glucose sensor exhibits stable stability for two weeks and can be successfully applied to screen-printed carbon electrodes (SPCE), demonstrating its great potential for personalized medical detection and chronic disease management.