A highly sensitive nonenzymatic glucose sensor based on CuO nanowires

We report on the sensitive determination of glucose using a glassy carbon electrode modified with CuO nanowires and a Nafion film. The structure and morphology of CuO nanowires were established by scanning electron microscopy and X-ray diffraction. The electrochemical performance of the modified electrode was investigated by cyclic voltammetry and chronoamperometry. Compared to a bare glassy carbon electrode, a substantial increase in efficiency of the electrocatalytic oxidation of glucose can be observed. The new glucose sensor displays two useful linear ranges of response towards glucose, is not affected by commonly interfering species, and displays a detection limit as small as 45?nM. The response time is <2?s towards 0.5?mM of glucose. Additional features include high electrocatalytic activity, high sensitivity, excellent selectivity, and good stability.

Study of the nonenzymatic glucose sensor based on highly dispersed Pt nanoparticles supported on carbon nanotubes

An amperometric biosensor for sensitive and selective detection of glucose has been constructed by using highly dispersed Pt nanoparticles supported on carbon nanotubes (Pt-MWCNTs) as sensing interface. The Pt-MWCNTs were synthesized by using the two-step pyrolysis method. This composite shows good electrocatalytic activity towards the oxidation of glucose in alkaline and thus can be used to selectively detect glucose. We found that detection potential and Nafion amount covered on the Pt-MWCNTs modified glassy carbon electrode had considerable influence on the selectivity for amperometric detection of glucose. Under optimal detection conditions (detection potential of 0.0 V versus SCE and 10 μL 1.5% Nafion), selective detection of glucose in the glucose concentration range of 1.0-26.5 mM (correlation coefficient, >0.999) can be performed. The results demonstrate that the Pt-MWCNTs composite is promising for the fabrication of nonenzymatic glucose sensors.     

基于层层组装钴铝水滑石/聚电解质包裹碳纳米管的无酶葡萄糖传感器

采用共沉淀法合成了钴铝水滑石(CoAl-LDH),将CoAl-LDH与PSS包裹的CNTs(CNTs@PSS)通过层层自组装法构筑CNTs@PSS/CoAl-LDH多层膜电极,并将其应用于葡萄糖的分析测定。X射线衍射光谱、红外光谱和SEM表明:共沉淀法合成的CoAl-LDH具有典型的水滑石特征峰及形貌。电化学阻抗谱表明:CoAl-LDH可与CNTs@PSS均匀有效地组装构筑多层膜。电化学研究表明:CNTs的引入很好地提高了CoAl-LDH修饰电极的灵敏度。研究结果表明该传感器对葡萄糖在3.0×10-6～4.98×10-4mol/L范围内呈良好的线性响应,灵敏度为1.03×10-3A.L/mol。     

一种基于多壁碳纳米管的高灵敏捕获水样中细菌的纳米富集钓竿装置

碳纳米管因其独特的性质在生物检测方面具有广泛应用.本文基于DNA与多壁碳纳米管的相互作用而制成了作为一种新型纳米钓竿并用于水样中细菌的富集和检测.该钓竿的制备首先使用戊二醛为连接剂将经硅烷化处理的方形石英毛细管与氨基修饰的DNA相连,再依据单链DNA能缠绕多壁碳纳米管的性质将多壁碳纳米管固载在石英毛细管上制成一个纳米富集的钓竿装置.由于多壁碳纳米管与细菌细胞膜有较强的天然亲和力,因而能主动捕获细菌.实验证明,以大肠杆菌为目标检测菌,＂纳米鱼竿＂最短检测时间为15min,检测限为6.25×10CFU/mL,可以对饮用水等进行实时快速的细菌总数限量检测.     

A highly sensitive non-enzymatic glucose sensor based on a simple two-step electrodeposition of cupric oxide (CuO) nanoparticles onto multi-walled carbon nanotube arrays

A novel, stable and highly sensitive non-enzymatic glucose (Glc) sensor was developed using vertically well-aligned multi-walled carbon nanotubes array (MWCNTs) incorporated with cupric oxide (CuO) nanoparticles. The MWCNTs array was prepared by catalytic chemical vapor deposition on a tantalum (Ta) substrate, while a simple and rapid two-step electrodeposition technique was used to prepare the CuO-MWCNTs nanocomposite. First, Cu nanoparticles were deposited onto MWCNTs at constant potential and then they were oxidized into CuO by potential cycling. The electrocatalytic activity of CuO-MWCNTs array was investigated for Glc under alkaline conditions using cyclic voltammetry and chronoamperometry. The sensor exhibited a linear response up to 3 mM of Glc and sensitivity of 2190 μA mM⁻¹ cm⁻², which is two to three orders of magnitude higher than that of most non-enzymatic Glc sensors reported in the literature. The sensor response time is less than 2 s and detection limit is 800 nM (at signal/noise = 3). When tested with human blood serum samples, the sensor exhibited high electrocatalytic activity, stability, fast response and good selectivity against common interfering species, suggesting its potential to be developed as a non-enzymatic Glc sensor.     

Non-enzymatic analysis of glucose on printed films based on multi-walled carbon nanotubes

We report on the fabrication of an enzyme–free electrochemical sensor for glucose based on a printed film consisting of multi–walled carbon nanotubes (MWCNTs). The MWCNT–based film can be produced by means of a flexographic printing process on a polycarbonate (PC) substrate. The electrochemical response of the MWCNT–based film (referred to as MWCNT–PC) towards the oxidation of glucose at pH 7 was studied by means of cyclic voltammetry and electrochemical impedance spectroscopy. The MWCNT–PC film exhibits substantial electrocatalytic activity towards the oxidation of glucose at an anodic potential of 0.30?V (vs. Ag/AgCl). The findings reveal that the MWCNT–PC film enables non–enzymatic sensing of glucose with a detection limit as low as 2.16?μM and a sensitivity of 1045?μA?mM^?1?cm^?2.

Synthesis of highly nitrogen-doped multi-walled carbon nanotubes

We present a new synthesis route for nitrogen doped carbon nanotubes (CNx) based on the aerosol method. Tubes with a record high concentration of nitrogen (approximately 20 atom%) have been synthesized, confirmed by electron energy loss spectroscopy (EELS). A strong correlation between the N/C ratio and morphology of the tubes is observed and discussed.     

A highly sensitive hydrogen peroxide amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes

In this report, a highly sensitive amperometric sensor based on MnO₂-modified vertically aligned multiwalled carbon nanotubes (MnO₂/VACNTs) for determination of hydrogen peroxide (H₂O₂) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO₂/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H₂O₂ at the MnO₂/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO₂/VACNTs nanocomposite electrode exhibits a linear dependence (R = 0.998) on the concentration of H₂O₂ from 1.2 × 10⁻⁶ M to 1.8 × 10⁻³ M, a high sensitivity of 1.08 × 10⁶ μA M⁻¹ cm⁻² and a detection limit of 8.0 × 10⁻⁷ M (signal/noise = 3). Meanwhile, the MnO₂/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and d-(+)-glucose, etc. In addition, the sensor based on the MnO₂/VACNTs nanocomposite electrode was applied for the determination of trace of H₂O₂ in milk with high accuracy, demonstrating its potential for practical application.     

Electrochemical chlorine sensor with multi-walled carbon nanotubes as electrocatalysts

It has been reported for the first time that an electrochemical gas sensor modified with multi-walled carbon nanotubes (MWNTs) film as electrocatalyst was fabricated for the determination of chlorine (Cl₂).Here, MWNTs and graphite were compared with each other in terms of their electrochemical properties using cyclic voltammetry. Cl₂ gas was allowed through the cathode surface of the sensor and the resulting galvanic effects were monitored. Results indicated that both of the MWNTs and graphite have the electrocatalytic activity for the reduction of Cl₂ while the MWNTs-modified electrode exhibited a higher accessible surface area in electrochemical reactions, excellent sensitivity, stable response, reproducibility and recovery for the determination of Cl₂.     

Highly selective tryptophan enantiomers electrochemical chiral sensor based on poly-lysine and functionalized multi-walled carbon nanotubes

Journal of Solid State Electrochemistry - A novel electrochemical chiral sensor was reported for recognizing tryptophan enantiomers based on multi-walled carbon nanotubes functionalized by...     

A nonenzymatic sensor for xanthine based on electrospun carbon nanofibers modified electrode

Xanthine (Xa) determination is of considerable importance in clinical analysis and food quality control. Therefore, a sensitive nonenzymatic amperometric sensor for Xa based on carbon nanofibers (CNFs) has been proposed. The CNFs, which were prepared by electrospinning technique and subsequent thermal treatment, were used to modify carbon paste electrode (CNF-CPE) to construct the amperometric sensor device without any oxidation pretreatment. In application to Xa electrochemical determination, the CNF-CPE exhibited high electrocatalytic activity and fast amperometric response. Various experimental parameters, such as pH and applied potential were optimized. Under the optimal conditions, the dynamic linear range of Xa was 0.03-21.19 μM (R = 0.9992) with the detection limit low to 20 nM (S/N = 3). With good selectivity and sensitivity, the present system was successfully applied to estimate the freshness of fish and determine Xa in human urine, which provides potential application in food quality control and clinical analysis.     

Highly sensitive and wide-range nonenzymatic disposable glucose sensor based on a screen printed carbon electrode modified with reduced graphene oxide and Pd-CuO nanoparticles

A nanocomposite consisting of reduced graphene oxide decorated with palladium-copper oxide nanoparticles (Pd-CuO/rGO) was synthesized by single-step chemical reduction. The morphology and crystal structure of the nanocomposite were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction analysis. A 3-electrode system was fabricated by screen printing technology and the Pd-CuO/rGO nanocomposite was dropcast on the carbon working electrode. The catalytic activity towards glucose in 0.2 M NaOH solutions was analyzed by linear sweep voltammetry and amperometry. The steady state current obtained at a constant potential of +0.6 V (vs. Ag/AgCl) showed the modified electrode to possess a wide analytical range (6 μM to 22 mM), a rather low limit of detection (30 nM), excellent sensitivity (3355 μA∙mM⁻¹∙cm⁻²) and good selectivity over commonly interfering species and other sugars including fructose, sucrose and lactose. The sensor was successfully employed to the determination of glucose in blood serum.

A highly sensitive nonenzymatic electrochemical sensor was fabricated using a Pd-CuO composite with reduced graphene oxide. The sensor has a wide detection range and was used to sense glucose in blood serum

     

A uric acid sensor based on electrodeposition of nickel hexacyanoferrate nanoparticles on an electrode modified with multi-walled carbon nanotubes

An electrode sensitive to uric acid was prepared by electrodeposition of nickel(II) hexacyanoferrate(III) on the surface of a glassy carbon electrode modified with multi-walled carbon nanotubes. The morphology of the material was characterized by scanning electron microscopy and Fourier transform infrared spectrometry. The modified electrode were characterized via cyclic voltammetry and amperometry (i - t). It exhibited efficient electron transfer ability and a strong and fast (< 3?s) response towards uric acid which is linear in the range from 0.1???M to 18???M, with a lower detection limit of 50 nM (at an S/N ratio of 3). In addition, the electrode exhibited good reproducibility and long-term stability.

Sensitive and selective molecularly imprinted electrochemical sensor based on multi-walled carbon nanotubes for doxycycline hyclate determination

An electrochemical sensor for doxycycline hyclate(DC)detection with high sensitivity and good selectivity is reported.The sensor was fabricated by electro-polymerization of molecularly imprinted polymers(MIPs)in the presence of DC onto multi-walled carbon nanotubes modified glassy carbon electrode(MWCNTs/GCE).The MWCNTs can significantly increase the current response of the sensor,leading to enhanced sensitivity.The MIPs provide selective recognition sites for DC detection.The experimental parameters,such as the polymer monomer concentration,supporting electrolyte pH,the time for electro-polymerization and the incubation time of the sensor with DC were optimized.Under optimized experimental conditions,the sensor displayed a linear range of 0.05μmol/L-0.5μmol/L towards DC detection,with the detection limit of 1.3×10^-2μmol/L.The sensor was successfully applied for recovery test of DC in human serum samples.     

Affinity-based elimination of aromatic VOCs by highly crystalline multi-walled carbon nanotubes

Carbon nanotubes (CNTs) are capable of adsorbing pollutant chemicals. Their adsorptive capacities and adsorbing mechanisms, however, are not fully understood. As-grown CNTs often contain both crystalline and amorphous carbon, and the ratio of carbon types can affect adsorption. In this study, highly crystalline multi-walled carbon nanotubes (HC-MWCNTs) were used as the adsorbent for volatile organic compounds (VOCs) in contaminated air samples. Air containing 23 added VOCs (1,1-dichloroethylene, dichloromethane, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, chloroform, 1,1,1-trichloroethane, carbon tetrachloride, 1,2-dichloroethane, benzene, trichloroethylene, 1,2-dichloropropane, bromodichloromethane, cis-1,3-dichloropropene, toluene, trans-1,3-dichloropropene, 1,1,2-trichloroethane, tetrachloroethylene, dibromochloromethane, m-xylene, p-xylene, o-xylene, bromoform, and p-dichlorobenzene) was used for model samples. Adsorptive experiments were carried out by passing the air samples through a cartridge packed with HC-MWCNTs. Initial results showing high selectivity and high affinity for adsorbing aromatic VOCs (benzene, toluene, m-xylene, p-xylene, o-xylene, and p-dichlorobenzene) have provided new insight into the adsorption mechanisms. Data suggest that the HC-MWCNTs, unlike conventional carbon materials, adsorb aromatic compounds according to Fukui's frontier theory, which is based on the interactions between the HOMO and LUMO of the aromatic VOCs and those of the HC-MWCNTs.     

Rich-defect carbon nanotubes for highly sensitive detection of Dopamine

Dopamine (DA) plays an essential role in the central nervous, renal, hormonal and cardiovascular systems. Various modified carbon nanotubes (CNT)-based dopamine sensors have been reported, but inexpensive, highly sensitive plain CNT-based ones are seldom studied. In this work, a facile and inexpensive CNT-based DA sensor is made by rich-defect multi-walled carbon nanotubes (RD-CNT) via an ultrasound method. The defect and elemental states of the RD-CNT are systematically studied by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), Raman spectroscopy, X-ray powder diffraction (XRD) and X-ray-photoelectron spectroscopy (XPS). Results show that massive holes and cracks exist in RD-CNT. The level of defects increases from the additional exposed edges. The electrochemical characterizations indicate that the electrochemical sensor has the highest sensitivity of 438.4 μA/(μM ⋅ cm²) among all carbon materials-based DA sensors while well meeting the clinically required detection range and selectivity. The DA sensor was further used to detect live healthy human serum and live PC12 cells with satisfactory results, thus holding great promise for an inexpensive but sensitive DA sensor in practical applications of clinical diagnosis and biological research.     

A highly sensitive and selective dimethyl ether sensor based on cataluminescence

A sensor for detecting dimethyl ether was designed based on the cataluminescence phenomenon when dimethyl ether vapors were passing through the surface of the ceramic heater. The proposed sensor showed high sensitivity and selectivity to dimethyl ether at an optimal temperature of 279 °C. Quantitative analysis were performed at a wavelength of 425 nm, the flow rate of carrier air is around 300 mL/min. The linear range of the cataluminescence intensity versus concentration of dimethyl ether is 100-6.0 × 10³ ppm with a detection limit of 80 ppm. The sensor response time is 2.5 s. Under the optimized conditions, none or only very low levels of interference were observed while the foreign substances such as benzene, formaldehyde, ammonia, methanol, ethanol, acetaldehyde, acetic acid, acrolein, isopropyl ether, ethyl acetate, glycol ether and 2-methoxyethanol were passing through the sensor. Since the sensor does not need to prepare and fix up the granular catalyst, the simple technology reduces cost, improves stability and extends life span. The method can be applied to facilitate detection of dimethyl ether in the air. The possible mechanism of cataluminescence from the oxidation of dimethyl ether on the surface of ceramic heater was discussed based on the reaction products.