Carboxylic Multi-walled Carbon Nanotubes Research Articles

Electrochemical Immunosensor Modified with Nitrogen-Doped Reduced Graphene Oxide@Carboxylated Multi-Walled Carbon Nanotubes/Chitosan@Gold Nanoparticles for CA125 Detection

Lung cancer is one of the malignant tumors with the highest mortality rate, and the detection of its tumor marker carcinoma antigen 125 (CA125) is significant. Here, an electrochemical immunoassay for CA125 was described. Nitrogen-doped reduced graphene oxide (N-rGO), carboxylated multi-walled carbon nanotubes (CMWCNTs) and gold nanoparticles (AuNPs) were applied to co-modify glassy carbon electrode (GCE), after incubation with Anti-CA125, the modified electrode was employed for the specific detection of CA125. The N-rGO@CMWCNTs (Nitrogen-doped reduced graphene oxide@carboxylated multi-walled carbon nanotubes) were used as a matrix, while CS@AuNPs (Chitosan@gold nanoparticles) with high conductivity and biocompatibility was immobilized on it through the reaction between carboxyl groups from CMWCNTs and amino groups, hydroxyl groups from chitosan (CS), resulting in the effect of double signal amplification. The immunosensor demonstrated excellent electrochemical performance with a linear detection range of 0.1 pg mL−1–100 ng mL−1, and the detection limit was as low as 0.04 pg mL−1 (S/N = 3). It had been verified that this method had good precision and high accuracy, and the immunosensor could remain stable for 10 days. This research provided a new method for the detection of CA125 in serum.

Carbon aerogels derived from waste paper for pipette-tip solid-phase extraction of triazole fungicides in tomato, apple and pear

In order to develop environmentally friendly, economical and facile preparation method of carbon aerogels (CAs), the waste printing paper as the raw material was combined with graphene oxide and carboxylic multi-walled carbon nanotubes to produce CAs (ρ = 44 mg cm−3). The CAs with different composition were investigated, the addition of graphene oxide led to the reduction of adsorption sites and the reduction of extraction performance. But the carbon nanotubes made CAs have a better pore structure. The CAs as adsorbent were loaded into a pipette-tip for solid-phase extraction of hexaconazole and diniconazole. Coupled with gas chromatography, an analytical method was established under the optimized conditions. The limits of detection were between 0.08 and 0.32 mg kg−1, the linear ranges were 0.96–200.0 mg kg−1 and 0.24–200.0 mg kg−1. The relative recoveries were in the range of 81.0–119%. The results indicated that the method had potential application for the determination of triazole fungicides.

Hierarchical Carbon Nanotube‐Supported Conductive Metal–Organic Framework Nanosheet toward High‐Strain Ionic Soft Actuator

AbstractConductive metal–organic frameworks (MOFs) have recently been applied in electroactive ionic actuators due to their high surface areas and fast ion migration. However, their actuation performance needs to be promoted in terms of high conversion efficiency and large strain. Here, a soft ionic actuator is assembled by designing a hierarchical Cu‐MOFs‐based active material, which is composed of conductive Cu‐catecholate (Cu‐CAT) nanosheets covalently bridged by carboxylic multiwall carbon nanotubes (Cu‐CAT@MWCNT). Benefited from the large electromechanical deformation and rapid response rate of the Cu‐CAT@MWCNT electrodes, the assembled soft actuator exhibits large displacement of 16.6 mm with high bending strain of 0.52% (AC of ±3 V) and a high energy conversion efficiency (3.02%) with cycling stability over 10 000 cycles (in frequency range of 0.1–10 Hz). In addition, it demonstrates the capacity of gripping objects when assembled on a robot. The Cu‐CAT@MWCNT hybrid material‐based electrode points out a feasible pathway to construct soft actuators with improved performance and broadens their applications.

Preparation of a hydroxyapatite–silver gradient bioactive ceramic coating with porous structure by laser cladding: A study of in vitro bioactivity

Porous coatings play a critical role in osseointegration between the artificial joint implant and host bone. Herein, a previously developed hydroxyapatite–silver (HA-Ag) gradient bioactive ceramic coating with a three-layer structure is further improved. Through laser cladding, a bioactive porous ceramic coating was prepared by adding carboxyl multi-walled carbon nanotubes (CMWCNTs) to HA powder. In this study, the effects of the added amount of CMWCNTs on the pore size, porosity, and active substance content were investigated. The results showed that the porous structure of the bioactive surface layer was gradually changed from the round hole shape to the reticular porous shape when the addition amount of CMWCNTs was increased from 5 wt % to 20 wt %, and the most appropriate amount of CMWCNTs was 10 wt %. In addition, the biocompatibility of the porous ceramic coating, as well as its effect on the alkaline phosphatase (ALP) activity of osteoblasts, were evaluated in vitro. Simulated body fluid (SBF) soaking tests were applied to determine the changes in ion concentration and calculate the concentration quotient and transfer free energy of Ca2+ and PO43− during the soaking period in SBF. The effects of the porous ceramic coating on the nucleation and growth of HA were also validated. The results showed that the preparation of the gradient porous ceramic coating was beneficial to the nucleation and growth of apatite, further improving the bioactivity of the coating to achieve osseointegration between the artificial joint implant and host bone.

In-situ growth of cerium-based metal organic framework on multi-walled carbon nanotubes for electrochemical detection of gallic acid

Gallic acid (GA) is a valuable polyphenolic compound. GA has a strong antioxidant effect, and its biological properties are anti-inflammatory, anti-histamine, anti-tumor, scavenging free radicals and protecting cardiovascular disease. Therefore, accurate and fast determination of gallic acid content is of great significance to human health. A simple and responsive electrochemical sensor for the detection of gallic acid was constructed by modifying glassy carbon electrodes with the CeMOF/MWCNTs composites synthesized by in situ growth of Ce metal organic framework (CeMOF) on carboxylic acid-functionalized multi-walled carbon nanotubes. The nanomaterials were characterized accurately by X-ray diffraction (XRD), X-ray photoelectron spectroscop (XPS) and scanning electron microscopy (SEM) and so on. Under the optimized conditions, the linear range of the sensor to detect gallic acid is 1.5 μM-200 μM, and the LOD is 0.14 μM (S/N = 3). The sensor can detect gallic acid in tea with good repeatability, stability and anti-interference.

A self-powered microbiosensor system for specific bacteria detection based on triboelectric nanogenerator

Gram-negative bacteria (Gnb) such as sulfate-reducing bacteria (SRB), as the main culprits of microbiological induced corrosion (MIC) in marine environment, cause severe problems for marine construction. Thus, the rapid and sensitive detection of Gnb is vital for environmental monitoring and metal corrosion protection. Herein, we developed a microbiosensor system based on triboelectric nanogenerator (TENG), by which Gnb such as SRB in the solution can be detected instantly. In the system, concanavalin A (ConA)-modified indium tin oxide glass (ITO-ConA) captures Gnb by specific recognition between ConA and Gnb; ConA-functionalized carboxyl multi-walled carbon nanotubes with high-conductivity serve as signal amplification material; and TENG provides a stable power supply to the microbiosensor system. Variation of Gnb concentration leads to changes in the adsorption capacity of CNT-ConA, which further results in the variation of resistance. Thus, the microbiosensor system could effectively detect the bacteria concentration based on the monitoring of output voltage. In addition, by integrating alarm circuit with microbiosensor, the detection results can be can be directly indicated by light emitting diode. Desulforibrio sp. Huiquan2017 was chosen as typical SRB for validating the performance of the as-obtained self-powered microbiosensor. In the detection range of 3 × 103 to 3 × 107 CFU mL−1, the correlation between peak voltage and bacteria concentration exhibits linear relation. Meanwhile, the detection mechanisms were further elucidated by adopting molecular simulations. This work not only offers an effective strategy for detecting Gnb, but also provides useful insights into the development of portability, specificity, and stability of TENG-based sensor systems.

Anodic Stripping Voltammetric Analysis of Trace Arsenic(III) on a Au-Stained Au Nanoparticles/Pyridine/Carboxylated Multiwalled Carbon Nanotubes/Glassy Carbon Electrode.

A Au-stained Au nanoparticle (Aus)/pyridine (Py)/carboxylated multiwalled carbon nanotubes (C-MWCNTs)/glassy carbon electrode (GCE) was prepared for the sensitive analysis of As(III) by cast-coating of C-MWCNTs on a GCE, electroreduction of 4-cyanopyridine (cPy) to Py, adsorption of gold nanoparticles (AuNPs), and gold staining. The Py/C-MWCNTs/GCE can provide abundant active surface sites for the stable loading of AuNPs and then the AuNPs-initiated Au staining in HAuCl4 + NH2OH solution, giving a large surface area of Au on the Aus/Py/C-MWCNTs/GCE for the linear sweep anodic stripping voltammetry (LSASV) analysis of As(III). At a high potential-sweep rate of 5 V s−1, sharp two-step oxidation peaks of As(0) to As(III) and As(III) to As(V) were obtained to realize the sensitive dual-signal detection of As(III). Under optimal conditions, the ASLSV peak currents for oxidation of As(0) to As(III) and of As(III) to As(V) are linear with a concentration of As(III) from 0.01 to 8 μM with a sensitivity of 0.741 mA μM−1 and a limit of detection (LOD) of 3.3 nM (0.25 ppb) (S/N = 3), and from 0.01 to 8.0 μM with a sensitivity of 0.175 mA μM−1 and an LOD of 16.7 nM (1.20 ppb) (S/N = 3), respectively. Determination of As(III) in real water samples yielded satisfactory results.

Carboxylic Multi‐Walled Carbon Nanotubes as Reinforcing Fillers in Ionic Polymer–Metal Composite Actuators with Enhanced Driving Performance

Although huge attentions are paid to the bionic robot research, preparing flexible actuators with high sensitivity, fast response, and long lifespan are still in great challenge. Herein, an enhanced actuator based on the ionic polymer–metal composite (IPMC) and carboxylic multi‐walled carbon nanotubes (CMWCNTs) is presented. The nanoscale decoration of MWCNT materials leads to the effectively application of doped and decorated carbon‐based devices for actuators. In the study, morphologies of CMWCNTs are evaluated with transmission electron microscope (TEM) and scanning electron microscope (SEM). By the home‐setup platform, the electrical conductivity and driving performance are evaluated. Using tensile‐testing machine, mechanical properties, such as the elastic modulus and tensile strength, are assessed. Results show that performances including electronic, mechanical, and driving activities of the ionic polymer–metal composite actuator are significantly improved. The maximum output force and sensitivity of the actuators are increased at rates of 24% and 130%, respectively. The mechanism is attributed to carboxylic groups in the acceleration of hydrated cations movement. Additionally, the surface conductivity, mechanical strength, and dispersion are far superior to those walled carbon nanotubes (WCNT)‐doped actuators reported previously. IPMC‐embedded nanotube designs provide a high potential for the development of robotic‐assisted manipulations, such as biomedical robots and microelectromechanical systems.

Development of cellulose acetate membrane performance by carboxylate multiwalled carbon nanotubes

Nanocomposite reverse osmosis (RO) membranes were developed using cellulose acetate (CA) and various amounts of the carboxylated multiwalled carbon nanotubes (CMWCNTs) via phase inversion procedure. The prepared membranes were investigated by Raman and infrared spectroscopies, transmission electron microscope (TEM), scanning electron microscope (SEM), atomic force microscope (AFM), and water contact angle measurement to deduce the structural, morphological, and hydrophilic properties. The incorporation of CMWCNTs improved the performance and the hydrophilicity of the CA-RO membranes. AFM images of pure CA-RO and modified CA-RO membranes with 0.059 wt% CMWCNTs revealed that the surface roughness values were 202 nm and 7.04 nm, respectively. The salt rejection and the permeate water flux of the membranes were measured at a high salt concentration of 10,000 ppm and high salinity of 35,000 ppm NaCl solution using the cross-flow technique. The performance of the nanocomposite membranes at the optimum addition of CMWCNTs (0.059 wt%) produced the highest salt rejection of 98.5%, and permeate water flux value of 5.85 l m−2 h−1. At higher CMWCNTs concentrations (0.177 wt%), the salt rejection was declined to 76%.

Facile synthesis of nickel phosphate nanorods as biomimetic enzyme with excellent electrocatalytic activity for highly sensitive detection of superoxide anion released from living cells

In this work, the superoxide dismutase (SOD) biomimetic enzyme based on nickel phosphate nanorods [Ni(PO4)NRs] was prepared by a simple and eco-friendly hydrothermal method. After further introduction of carboxylated multi-walled carbon nanotubes (C-MWCNTs), the obtained Ni(PO4)NRs/C-MWCNTs nanocomposites were utilized as the novel electrode materials to construct the electrochemical superoxide anion radicals (O2•−) biosensor with excellent electrical conductivity and unprecedented catalytic performance. The morphology of Ni(PO4)NRs/C-MWCNTs nanocomposite was examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman microscope, respectively. Under the optimum conditions, the proposed biosensor exhibits high sensitivity (5.67 × 104 μA/mM/cm2), low detection limit (0.097 μM at S/N = 3) and good selectivity to O2•−. In addition, the sensor can monitor O2•− released from MCF-7 cells with satisfactory results, which provides a great opportunity to apply it in the field of fundamental research and clinical diagnostics. Our results would promote Ni(PO4)NRs as the SOD biomimetic enzyme for designing biosensor and expand its various applications in biocatalysis and bioanalysis.

Preparation of hollow-fiber nanofiltration membranes of high performance for effective removal of PFOA and high resistance to BSA fouling

Nanofiltration (NF) process has become one of the most promising technologies to remove micro-organic combined water pollution. Developing a NF membrane material with efficient separation for perfluorooctanoic acid (PFOA) combined pollution is highly desired, this manuscript targets this unmet need specifically. In this work, hydrophilic SiO2 nanoparticles with various contents blended with carboxylic multiwalled carbon nanotube were used to modify poly (m-phenylene isophthal amide) (SiO2/CMWCNT/PMIA) hollow fiber NF membrane. The modified membrane with 0.1 wt% SiO2 doping exhibits way better fouling resistance with irreversible fouling ratio decreased dramatically from 18.7% to 2.3%, and the recovery rate of water flux increases significantly from 81.2% to 97.7%. The separation experiment results had confirmed that the modified membrane could improve the rejection from 97.2% to 98.6% for perfluorooctanoic acid (PFOA) and its combined pollution with bovine serum albumin (BSA). It is clear that this reported SiO2/CMWCNT/PMIA hollow fiber NF membrane potentially could be applied in water treatment. This research also provides a theoretical basis for efficiently removal of PFOA and its combined pollution by NF membrane.

Enhanced electrochemical hydrogen storage performance of organophosphonic carboxylic acid-modified multiwalled carbon nanotubes/Bi2S3 composite

Hydrogen energy, one of the recognized green energy sources, has many advantages, and electrochemical hydrogen storage has been regarded as one of the outstanding energy storage systems. The present research describes that the organophosphonic carboxylic acid-modified multiwalled carbon nanotubes/Bi2S3 composite (OPCAMCN/BS) has been produced successfully by a facile solution reaction method, and it has been characterized by Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), and porous structure analysis. Because of the efficient synergistic effect of organophosphonic carboxylic acid-functionalized multiwalled carbon nanotubes and bismuth sulfide, the composite displays excellent electrochemical hydrogen storage and stability performances. The electrochemical hydrogen storage performance of the OPCAMCN/BS electrodes has been measured, and its discharge capacity (950.9 mAh/g) greatly exceeds the relevant values of those two reference materials, and the cycle life of the OPCAMCN/BS electrodes is higher than that of Bi2S3 and MWCNTs/BS. Furthermore, the as-synthesized composite OPCAMCN/BS exhibits very low charge transfer resistance which signifies fast electron transfer. Therefore, OPCAMCN/BS is expected to be used as a kind of excellent electrochemical hydrogen storage material and can be applied in the areas of renewable energy to reduce the use of fossil fuels.

Flame-Retardant and Alarm-Sensitive composite films by covalent modification of MWCNT with dopamine

Carboxylic multi-walled carbon nanotubes (MWCNTs–COOH) and dopamine were combined to prepare DCNT hybrid nanostructure through amidation reaction, and as-obtained materials were further used as fire retardants introduced into graphene oxide (GO) to fabricate GO/DCNT composite films. The corresponding PHRR (up to 98.58%), THR (utmost to 20.29%), TSR (over 99.09%), SPR (above 67.66%) values were reduced remarkably. As a similar trend, significant decreases of 95.74% and 99.16% in release of CO2 and CO were achieved. Flame retardant index (FRI) increased from 1.65 to 2.43, indicating the enhanced fire safety performance of GO. These positive results are attributed to the synergistic effect of gas phase flame retardant and condensed phase flame retardant between dopamine and MWCNTs. Raman spectra confirmed that the degree of graphitization of the carbon layer has been greatly improved, contributing to insulate the transfer of oxygen and heat. Meanwhile, GO/DCNT30 composite film exhibits ultra-fast intelligent fire alarm response capability (1 s). This work will provide a new method for the preparation of high-efficiency flame-retardant and ultra-fast intelligent fire alarm response materials.

NiII NPs entrapped within a matrix of l-glutamic acid cross-linked chitosan supported on magnetic carboxylic acid-functionalized multi-walled carbon nanotube: a new and efficient multi-task catalytic system for the green one-pot synthesis of diverse heterocyclic frameworks.

In the present study, a new l-glutamic acid cross-linked chitosan supported on magnetic carboxylic acid-functionalized multi-walled carbon nanotube (Fe3O4/f-MWCNT-CS-Glu) nanocomposite was prepared through a convenient one-pot multi-component sequential strategy. Then, nickelII nanoparticles (NiII NPs) were entrapped within a matrix of the mentioned nanocomposite. Afterward, the structure of the as-prepared Fe3O4/f-MWCNT-CS-Glu/NiII nanosystem was elucidated by various techniques, including FT-IR, PXRD, SEM, TEM, SEM-based EDX and elemental mapping, ICP-OES, TGA/DTA, and VSM. In the next part of this research, the catalytic applications of the mentioned nickelII-containing magnetic nanocomposite were assessed upon green one-pot synthesis of diverse heterocyclic frameworks, including bis-coumarins (3a–n), 2-aryl(or heteroaryl)-2,3-dihydroquinazolin-4(1H)-ones (5a–r), 9-aryl-3,3,6,6-tetramethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones (7a–n), and 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles (9a–n). The good-to-excellent yields of the desired products, satisfactory reaction rates, use of water solvent or solvent-free reaction medium, acceptable turnover numbers (TONs) and turnover frequencies (TOFs), along with comfortable recoverability and satisfying reusability of the as-prepared nanocatalyst for at least eight successive runs, and also easy work-up and purification procedures are some of the advantages of the current synthetic protocols.

Effect of baking, humidity and UV radiation on hexagonal boron nitride modified c-MWCNT nanohybrid electrodes

Electrically conducting nanohybrids (NHs) of hexagonal boron nitride (h-BN) with carboxylic functional multiwalled carbon nanotubes (c-MWCNT) have shown growing interest as electrode materials in microelectronics. This has been due to their ability to serve as potential electrically conducting materialsunder harsh environmental conditions of temperature, humidity and radiations. Present investigation demonstrates the development and characterisation of working electrodes (WEs) derived by coating of NHs and polyvinyl butyryl suspension in N-methyl-2-pyrrolidone (NMP) over stainless steel current collector. Field emission scanning electron microscopy (FESEM) and thermogravimetric analysis in air were used to examine the surface morphology and thermal stability of NHs. Effect of baking time (BT), humidity exposure (HE) and photo aging (PA) on functionality and performance of WEs has been investigated. The DC conductivity (σDC) of WEs increased somewhat with BT, reaching 0.97 upto 3 hr. Increasing BT to 6.0 hr resulted in a slight fall in the σDC of WEs to 0.94, which thereafter remained static at 0.92 at 9.0 hr. Under UV exposure for 3 hr, the σDC of WEs reached to 1.12. The σDC of WEs has been reduced to 0.99 after further 6 hr of irradiation and later it has reached to 0.98 after 9 hr of irradiation of WEs. The σDC of NHs under HE conditions was found in increasing order ranging from 0.96 to 1.14 for 0 to 3 hr and further marginal reduction from 1.11 to 1.10 for 6 to 9 hr.

A Highly Sensitive Modified Glassy Carbon Electrode with a Carboxylated Multi-walled Carbon Nanotubes/Nafion Nano Composite for Voltammetric Sensing of Dianabol in Biological Fluid.

The extraordinary prerequisite for the analysis of an anabolic steroid, namely dianabol (DB), has inspired towards the development of a cost-effective and high-performance sensing probe. Thus, a simple and robust electrochemical sensor (c-MWCNTs-Nafion®lGCE) for dianabol (DB), a widely used steroid, was developed using a glassy carbon electrode (GCE) modified with functionalized carboxylated multi-walled carbon nanotubes (c-MWCNT) and Nafion®. At pH 7 - 8, differential pulse-cathodic stripping voltammetry (DP-CSV) displayed two cathodic peaks at -0.85 and -1.35 V that varied linearly over a wide range (9.0 × 10-9 (2.7 μg L-1) - 9.0 × 10-6 (2.7 × 103 μg L-1) mol L-1) and 2.9 × 10-6 (8.7 × 102 μg L-1) - 8.0 × 10-5 (2.4 × 104 μg L-1) mol L-1) of DB concentrations, respectively. The low limits of detection and quantification at peak I (-0.85 V) were 2.7 × 10-9 (8.1 × 10-1 ng mL-1) and 9.0 × 10-9 (2.7 ng mL-1) mol L-1, respectively. The repeatability and reproducibility displayed relative standard deviations lower than 5%. The method was applied for DB analysis in human urine and subsequently compared with the standard HPLC method. Interference of common metabolites in biological fluids samples to DB sensing was insignificant. This method has distinctive advantages e.g. precise, short analytical time, sensitive, economical, reproducible and miniaturized sample preparation for DB analysis in biological samples of human origin.

A multi-plug filtration (m-PFC) cleanup method based on carboxylic multi-walled carbon nanotubes for the detection of 14 perfluorinated compounds and dietary risk assessment of chicken, beef, and mutton collected from Shanghai markets

Dietary intake is a major pathway of human exposure to perfluorinated compounds (PFCs). Livestock and poultry meats (chicken, beef, mutton) account for a significant proportion of dietary consumption in China, and thus it is crucial to investigate the levels and composition profiles of PFCs in consumer meats to assess and mitigate potential health risks. However, rapid and simple analytical methods for such investigations are lacking. This study addresses this shortcoming by developing a rapid filtration clean-up method using carboxylic multi-walled carbon nanotubes (CMWCNTs) for the detection of 14 PFCs. Good linearities (R2 > 0.99) were obtained for all 14 PFCs in chicken, beef, and mutton. Recoveries ranged from 65 to 145% (except perfluorotetradecanoic acid, PFTeDA) with relative standard deviations (RSDs) lower than 16%. Method limits of detection (LODs) were between 0.12 and 0.83 ng g−1d.w. Subsequently, this method was applied for the analysis of 46 livestock and poultry meat samples collected from markets in Shanghai. PFCs were detected in all samples with total concentrations of 1.61–4.27 ng g−1 wet weight (w.w) in chicken, 1.51–5.56 ng g−1 w.w in beef and 1.61–8.15 ng g−1 w.w in mutton. Perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) were the predominant compounds in these samples and accounted for over 92% of ΣPFCs. For regulated compounds such as PFOA, risk quotients (RQs) were determined to be much lower than 1. This suggests that chicken, beef, and mutton from Shanghai market pose very low PFC exposure risk to residents. However, high detection frequency of the unregulated PFBA demands further investigation of short-chain PFCs in consumer meats.

Electrochemical Detection of Dopamine Using a Prussian Blue Carbon Nanotube Composite Decorated with Agglomerated ZnO Particles

A Prussian Blue (PB) zinc oxide (ZnO) nanoparticle carboxylic acid-functionalized multiwalled carbon nanotube (PB/ZnO/COOH-MWNT) composite was fabricated for the determination of dopamine (DA). ZnO nanoparticles were tethered to COOH-MWNTs using sonication. Upon attachment of the PB to the ZnO/COOH-MWNTs, which consisted of ZnO nanoparticles 13 nm in diameter, the ZnO coalesced to larger clusters with an average diameter of 573 ± 4 nm. The current response versus various concentrations of DA was measured using chronoamperometry. The optimum conditions for DA measurements were at pH 7.0 using the oxidation current. The sensor has a linear dynamic range from 10 to 900 μM with a limit of detection of 0.378 ± 0.015 μM, suitable for practical neuroblastoma screening at the lower concentration range and process controls for polydopamine synthesis at the upper concentration range, important for modifying polymeric membranes for water purification.

A sensitive electrochemical immunosensing interface for label-free detection of aflatoxin B1 by attachment of nanobody to MWCNTs-COOH@black phosphorene.

A label-free electrochemical immunosensor has advantages of real-time and rapid detection, but it is weak in detection of small molecular toxins such as aflatoxin B1 (AFB1). The greatest obstacle to achieving this is that small molecules bound to a common immunosensing interface cannot interfere with electron transfer effectively and the detection signal is so weak. Therefore, a sensitive electrochemical immunosensing interface for small molecules is urgently needed. Here, we employed functionalized black phosphorene (BP) as electrode modification materials and anti-AFB1 nanobody (Nb) as a biorecognition element to construct a very sensitive immunosensing interface towards small molecular AFB1. The BP functionalized by carboxylic multi-walled carbon nanotubes (MWCNTs-COOH) via P-C bonding behaved with a satisfactory stability and good catalytic performance for the ferricyanide/ferrocyanide probe, while the small-sized Nb showed good compatibility with the functionalized BP and also had less influence on electron transfer than monoclonal antibody (mAb). Expectedly, the as-prepared immunosensing interface was very sensitive to AFB1 detection by differential pulse voltammetry (DPV) in a redox probe system. Under optimized conditions, a linear range from 1.0pM to 5.0nM and an ultralow detection limit of 0.27pM were obtained. Additionally, the fabricated immunosensor exhibited satisfactory stability, specificity, and reproducibility. The strategy proposed here provides a more reliable reference for label-free sensing of small molecules in food samples.

Conducting polymer ink for flexible and printable micro-supercapacitors with greatly-enhanced rate capability

Conducting polymer ink holds great promise for wearable, flexible, and printable high-power-density micro-supercapacitors (MSCs) but chronically suffers from the poor rate capability ascribing to naturally electron-blocked transferring. Herein, we devise an air-stable, easy-fabricating and rapid electron-transferring polyaniline ink by embedding conductive carboxylic multi-walled carbon nanotubes (C-MWCNTs) networks into polyaniline nanosheets. Due to the optimized electron-transferring kinetics, the rate capability of polyaniline ink is significantly increased by 73.7%. Additionally, the large-scale printable MSCs based on this ink deliver remarkable energy density of 2.6 mWh cm −3 , large areal capacitance of 45.4 mF cm −2 and excellent mechanics-electrochemistry stability with 84.6% capacitance retention against 1000 consecutive bending cycles. Evidently, this work provides the polyaniline ink for large-scale, printable, and flexible MSCs, which can underpin the next generation printed electronics in the approaching era of Internet of Things. Conducting polymer ink with greatly enhanced rate performance is successfully devised by embedding carboxylic MWCNTs into polyaniline nanosheets for scalable printing of high-performance micro-supercapacitors. 1. Conducting polymer ink is devised for scalable printing of micro-supercapacitor. 2. Rate capability is enhanced by 73.7% through embedding carboxylic MWCNTs. 3. Micro-supercapacitor with high energy density and good cyclic stability. 4. Capacitive contribution plays a dominant role according to quantitative calculation. 5. Proof-of-concept demonstration of various electronics as practical application.