Chlorpyrifos is a commonly used organophosphorus pesticide in agriculture. However, its neurotoxicity poses a huge threat to human health. To detect trace amounts of chlorpyrifos, we herein developed ...a regenerative electrochemical aptasensor for the sensitive detection of chlorpyrifos. The nanocomposite consisting of copper oxide nanoflowers (CuO NFs) and carboxyl-functionalized single walled carbon nanotubes (c-SWCNTs) was prepared to improve the sensing performance for chlorpyrifos detection. Various characterization methods such as scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) were used to demonstrate the successful fabrication of biosensor. Differential pulse voltammetry (DPV) was utilized to optimize test conditions and quantify chlorpyrifos. Under optimal conditions, the biosensor obtained a good linearity for chlorpyrifos ranging from 0.1 to 150ng/mL, with a lower detection limit of 70pg/mL. This aptasensor also exhibited high selectivity and outstanding repeatability, and was successfully applied to the determination of chlorpyrifos in spiked apple and celery cabbage with satisfactory recoveries. Furthermore, the sensor can be easily regenerated by urea for continuous application. With all the features, the proposed strategy provides an excellent platform for regenerative and selective detection of chlorpyrifos.
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•The synergic effect of CuO NFs and SWCNTs improved sensing performances of the electrochemical aptasensor.•The LOD of the aptasensor was as low as 70pg/mL.•The sensor can be easily regenerated by urea for continuous application.
Despite their potential as a next‐generation alternative to current state‐of‐the‐art lithium (Li)‐ion batteries, rechargeable aqueous zinc (Zn)‐ion batteries still lag in practical use due to their ...low energy density, sluggish redox kinetics, and limited cyclability. In sharp contrast to previous studies that have mostly focused on materials development, herein, a new electrode architecture strategy based on a 3D bicontinuous heterofibrous network scaffold (HNS) is presented. The HNS is an intermingled nanofibrous mixture composed of single‐walled carbon nanotubes (SWCNTs, for electron‐conduction channels) and hydrophilic cellulose nanofibers (CNFs, for electrolyte accessibility). As proof‐of‐concept for the HNS electrode, manganese dioxide (MnO2) particles, one of the representative Zn‐ion cathode active materials, are chosen. The HNS allows uniform dispersion of MnO2 particles and constructs bicontinuous electron/ion conduction pathways over the entire HNS electrode (containing no metallic foil current collectors), thereby facilitating the redox kinetics (in particular, the intercalation/deintercalation of Zn2+ ions) of MnO2 particles. Driven by these advantageous effects, the HNS electrode enables substantial improvements in the rate capability, cyclability (without structural disruption and aggregation of MnO2), and electrode sheet‐based energy (91 Wh kgelectrode−1)/power (1848 W kgelectrode−1) densities, which lie far beyond those achievable with conventional Zn‐ion battery technologies.
A 3D bicontinuous heterofibrous network scaffold (HNS), consisting of single‐walled carbon nanotubes and cellulose nanofibers, is presented as a new electrode architecture strategy for rechargeable aqueous Zn–MnO2 batteries. It allows the formation of bicontinuous electron/ion conduction pathways, thereby facilitating the redox kinetics of MnO2 particles without structural disruption and aggregation. The HNS‐based MnO2 electrode offers improvement in energy/power densities.
The development of omnidirectionally stretchable pressure sensors with high performance without stretching‐induced interference has been hampered by many challenges. Herein, an omnidirectionally ...stretchable piezoresistive pressure‐sensing device is demonstrated by combining an omniaxially stretchable substrate with a 3D micropattern array and solution‐printing of electrode and piezoresistive materials. A unique substrate structural design and materials mean that devices that are highly sensitive are rendered, with a stable out‐of‐plane pressure response to both static (sensitivity of 0.5 kPa−1 and limit of detection of 28 Pa) and dynamic pressures and the minimized in‐plane stretching responsiveness (a small strain gauge factor of 0.17), achieved through efficient strain absorption of the electrode and sensing materials. The device can detect human‐body tremors, as well as measure the relative elastic properties of human skin. The omnidirectionally stretchable pressure sensor with a high pressure sensitivity and minimal stretch‐responsiveness yields great potential to skin‐attachable wearable electronics, human–machine interfaces, and soft robotics applications.
An omnidirectionally stretchable, piezoresistive pressure‐sensing device is realized by combining a stress‐relieving and omniaxially stretchable substrate having regular 3D micropattern arrays with a solution‐processed silver‐paste electrode and a piezoresistive nanocomposite. This enables highly sensitive pressure responses while the in‐plane stretching responsivity is minimized. The device is demonstrated to detect body tremors and measure the relative elastic properties of human skin.
Programmed cell death-ligand 1 positive (PD-L1+) exosomes play a crucial role in the realm of cancer diagnosis and treatment. Nevertheless, due to the intricate nature of biological specimens, ...coupled with the heterogeneity, low refractive index (RI), and scant surface coverage density of exosomes, traditional surface plasmon resonance (SPR) sensors still do not meet clinical detection requirements. This study utilizes the exceptional electrical and optical attributes of single-walled carbon nanotubes (SWCNTs) as the substrate for SPR sensing, thereby markedly enhancing sensitivity. Furthermore, sp2 hybridized SWCNTs have the ability to load specific recognition elements. Additionally, through the coordination interaction of Ti with phosphate groups and the ferromagnetism of Fe3O4, efficient exosomes isolation and enrichment in complex samples are achievable with the aid of an external magnetic field. Owing to the high-quality and high-RI of Fe3O4@TiO2, the response signal experiences amplification, thus further improving the performance of the SPR biosensor. The linear range of the SPR biosensor constructed by this method is 1.0 × 103 to 1.0 × 107 particles/mL, with a limit of detection (LOD) of 31.9 particles/mL. In the analysis of clinical serum samples, cancer patients can be differentiated from healthy individuals with an Area Under Curve (AUC) of 0.9835. This study not only establishes a novel platform for exosomes direct detection but also offers new perspectives for the sensitive detection of other biomarkers.
The widespread adoption of e-nose devices based on chemiresistive materials has been hindered by issues related to sensor device complexity and reliability, specifically sensor drift, necessitating ...frequent recalibration and retraining of pattern recognition models. This study introduces a method for thermocycling a single sensor based on a free-standing network of single-walled carbon nanotubes (SWCNTs) to acquire signal patterns for selective analyte detection. Additionally, it employs a data filtering technique to compensate for the sensor drift. A free-standing SWCNT film, only a few nanometers thick, is thermally cycled via Joule heating between room temperature and 120 °C. Under these conditions, the sensitivity was tested towards NO2, H2S, and acetone vapors (10–25 ppm) in the mixture with dry air. Signal patterns produced through thermocycling were processed using CatBoost and LSTM algorithms. The accuracy of detection reached 90 % in the classification task, and the average root mean squared error of analyte concentration detection in the multioutput regression task was below 4 ppm. By combining original sensor design, thermocycling, signal filtering for drift compensation, and advanced pattern recognition models, this work contributes to overcoming the challenges in multivariate sensing systems, paving the way for practical applications of the more reliable chemiresistive sensors.
•A novel free-standing SWCNT film sensor design is reported.•Free-standing architecture facilitates efficient thermocycling through Joule heating.•NO2, H2S, and acetone at 10 – 25 ppm concentrations in dry air were detected.•Analyte detection accuracy using CatBoost for pattern recognition was 91 %.
Enzymes play a pivotal role in regulating numerous bodily functions. Thus, there is a growing need for developing sensors enabling real‐time monitoring of enzymatic activity and inhibition. The ...activity and inhibition of cholinesterase (CHE) enzymes in blood plasma are fluorometrically monitored using near‐infrared (NIR) fluorescent single‐walled carbon nanotubes (SWCNTs) as probes, strategically functionalized with myristoylcholine (MC)– the substrate of CHE. A significant decrease in the fluorescence intensity of MC‐suspended SWCNTs upon interaction with CHE is observed, attributed to the hydrolysis of the MC corona phase of the SWCNTs by CHE. Complementary measurements for quantifying choline, the product of MC hydrolysis, reveal a correlation between the fluorescence intensity decrease and the amount of released choline, rendering the SWCNTs optical sensors with real‐time feedback in the NIR biologically transparent spectral range. Moreover, when synthetic and naturally abundant inhibitors inhibit the CHE enzymes present in blood plasma, no significant modulations of the MC‐SWCNT fluorescence are observed, allowing effective detection of CHE inhibition. The rationally designed SWCNT sensors platform for monitoring of enzymatic activity and inhibition in clinically relevant samples is envisioned to not only advance the field of clinical diagnostics but also deepen further understanding of enzyme‐related processes in complex biological fluids.
Cholinesterase (CHE) activity is monitored in buffer and blood plasma using NIR fluorescent SWCNTs as probes. The SWCNTs are rationally functionalized with myristoylcholine (MC), a substrate of CHE, which, upon undergoing hydrolysis by CHE, leads to a decrease in the fluorescence intensity of SWCNTs. The decrease in the SWCNTs’ fluorescence is correlated to the amount of products formed due to MC hydrolysis.
A detailed analysis of TUBALL single‐walled carbon nanotubes (SWCNTs) after two‐step purification involving acid purification treatment with concentrated HCl, HNO3, H2SO4 and solution of HNO3:H2SO4 ...followed by magnetic processing is presented. The purity degree from iron higher than 99% is achieved, and the yield obtained by the above process is about 75 wt.%. Such high purity of the resultant sample is achieved by removing of the external iron nanoparticles by acid treatment and following extraction of nanotubes containing encapsulated nanoparticles under applied magnetic field. A comprehensive characterization of SWCNTs by Raman, optical absorption, and X‐ray photoelectron spectroscopies reveals purification‐induced changes in the integrity, composition, and electronic properties of SWCNT.
Contamination of single‐walled carbon nanotubes (SWCNTs) with residual catalyst particles restricts their practical applications. Here the effective post‐synthesis method for purification of SWCNTs from iron‐contained nanoparticles by an acid treatment followed by magnetic processing has been demonstrated. This route produces SWCNTs with high purity (≈99%) and yield (≈76%). Depending on acid used, defectiveness and length of nanotubes and entanglement of their bundles can be changed.
Infrared (IR) photodetection is important for light communications, military, agriculture, and related fields. Organic transistors are investigated as photodetectors. However, due to their large band ...gap, most organic transistors can only respond to ultraviolet and visible light. Here high performance IR phototransistors with ternary semiconductors of organic donor/acceptor complex and semiconducting single‐walled carbon nanotubes (SWCNTs), without deep cooling requirements are developed. Due to both the ultralow intermolecular electronic transition energy of the complex and charge transport properties of SWCNTs, the phototransistor realizes broadband photodetection with photoresponse up to 2600 nm. Moreover, it exhibits outstanding performance under 2000 nm light with photoresponsivity of 2.75 × 106 A W−1, detectivity of 3.12 × 1014 Jones, external quantum efficiency over 108%, and high Iphoto/Idark ratio of 6.8 × 105. The device exhibits decent photoresponse to IR light even under ultra‐weak light intensity of 100 nW cm−2. The response of the phototransistor to blackbody irradiation is demonstrated, which is rarely reported for organic phototransistors. Interestingly, under visible light, the device can also be employed as synaptic devices, and important basic functions are realized. This strategy provides a new guide for developing high performance IR optoelectronics based on organic transistors.
High performance ternary organic phototransistors with a photoresponse up to 2600 nm at room temperature are developed. The device exhibits a photoresponsivity of 2.75 × 106 A W−1 at 2000 nm. Moreover, the functions as synaptic devices are achieved. The overall performance is superior to that of previously reported organic infrared phototransistors.
Flexible photo‐thermoelectric (PTE) devices have great application prospects in the fields of solar energy conversion, ultrabroadband light detection, etc. A suitable manufacturing process to avoid ...the substrate effects as well as to create a narrow transition area between p–n modules for high‐performance freestanding flexible PTE devices is highly desired. Herein, an automated laser fabrication (ALF) method is reported to construct the PTE devices with rylene‐diimide‐doped n‐type single‐walled carbon nanotube (SWCNT) films. The wet‐compressing approach is developed to improve the thermoelectric power factors and figure of merit (ZT) of the SWCNT hybrid films. Then, the films are cut and patterned automatically to make PTE devices with various structures by the proposed ALF method. The freestanding PTE device with a narrow transition area of ≈2–3 µm between the p and n modules exhibits a high‐power density of 0.32 µW cm−2 under the light of 200 mW cm−2, which is among the highest level for freestanding‐film‐based PTE devices. The results pave the way for the automatic production process of PTE devices for green power generation and ultrabroadband light detection.
An all‐automated laser fabrication technique is reported for the preparation of flexible and freestanding photo‐thermoelectric (PTE) devices with single‐walled carbon nanotube films. The achieved PTE devices with a narrow p–n transition area of 2–3 µm exhibit high‐performance among the highest level for freestanding‐film‐based PTE devices.
Spontaneous exfoliation of single‐walled carbon nanotubes on dilution of dispersions in a common solvent, N‐methyl‐pyrrolidone, is demonstrated. The free‐energy of mixing is negative, confirming ...athermal solubility. Scanning tunneling microscopy measurements show physisorption of the solvent to the nanotube (see figure). Experiments, supported by a simple model, show that successful solvents for nanotubes are those with surface tensions close to that of graphite.
