Preparation of biomass N-doped carbon dots and detection of tioproninEI北大核心CSCD

Nitrogen-doped carbon dots (N-CDs) were prepared by one-step hydrothermal synthesis with pomegranate seeds as the carbon source and urea as the nitrogen source. Observed by transmission electron microscopy (TEM), average particle size of N-CDs was 20 nm. Observed by atomic force microscopy (AFM), the thickness of N-CDs was 0. 6-1. 4 nm. Fourier transform infra-red (FT-IR) confirmed the presence of water-soluble functional groups such as amino groups on the surface of N-CDs. With the prepared N-CDs as the target fluorophore, Hg2 + can efficiently bind to the surface of N-CDs to form a complex, and achieve static quenching. The addition of tiopronin can bind the Hg2 + in the complex to make the Hg2 + detach from the surface of N-CDs and realize fluorescence recovery. The nano fluorescence switch constructed in this work is more accurate and sensitive than the traditional detection method. The optimum conditions were determined by optimizing the pH value, reaction time, the dosage of N-CDs and Hg2 +. The relative deviation (RSD) was 4. 7%, and the detection limit was 0. 2 μmol/L. The method was used to determine the content of tiopronin in human serum samples with the recoveries of 97. 2%-101. 3%. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

The detection of bergenin based on the gold nanoparticles/chitosan/reduced graphene oxide modified electrodeEI北大核心CSCD

Gold nanoparticles (AuNPs)/chitosan (CS)/reduced graphene oxide (RGO) modified electrode was prepared. The electrochemical behaviors of bergenin on this modified electrode was investigated by cyclic voltammetry. The results showed that the proposed electrode exhibited an obvious electrocatalytic ability to the oxidation of bergenin. The differential pulse voltammetry was employed to detect bergenin in 0.1 mol/L phosphate buffer solution (pH 6.0). A good linear relationship between the oxidation peak current and the concentration of bergenin was found in the range of 2.0×10-7-1.2×10-6 mol/L with the detection limit of 6.0×10-8 mol/L (S/N=3).The prepared electrode had good anti-interference ability and potential application in the actual detection of bergenin. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Electrochemical preparation of nickel-iron hydroxide loaded on multi-walled carbon nanotubes electrode for the detection of ureaEI北大核心CSCD

A nickel-iron hydroxide/multi-walled carbon nanotubes MWCNTscomposite film electrode was prepared by electrochemical derivation of metal hexacyanoferrate in alkaline solution. MWCNTs film modified electrode was prepared by dropping methodthen Ni-Fe bimetal hexacyanoferrateNi-FeHCFnanoparticles were deposited on the surface of MWCNTs by cyclic voltammetry. This Ni-FeHCF/MWCNTs electrode was electrochemically derived in alkaline solution and a MWCNTs composite film electrodeNiOH2-FeOH3 /MWCNTs/ CCEwas obtained. The surface morphology and the electrochemical behavior of this modified electrode were characterized by scanning electron microscopeSEMand cyclic voltammetryCV. This electrode exhibited high catalytic activity for the electrochemical oxidation of urea under the synergistic action of each component. Based on thisthe non-enzymatic electrochemical sensing of urea was established. In 1.0 mol/L KOH solution the linear range of urea by amperometry was between 5.0×10−3 and 2.8 mmol/Land the detection limit was 3.6 μµmol/L. The sensitivity to urea was 54.3 μµA/mmol/L. This electrode could be used for the determination of urea in river water and human urine samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

双酚A在氮掺杂多壁碳纳米管修饰电极上的电化学行为及测定

构建了不同百分含量的氮掺杂的多壁碳纳米管化学修饰石墨电极,利用线性扫描伏安法及循环伏安法研究了双酚A(BPA)在修饰电极上的电化学行为。提出了一种灵敏、简便的直接检测双酚A的电化学分析方法。在pH6.98的PBS缓冲溶液中,在电位0.20 V富集后,该修饰电极在0.680 V出现一个灵敏的、峰形好的氧化峰。表明氮掺杂多壁碳纳米管薄膜对双酚A的氧化表现出一定的催化作用,能显著提高双酚A的氧化峰电流。在优化条件下,采用线性扫描伏安法对双酚A进行测定。双酚A的氧化峰电流与其浓度在2.5×10-7～1.0×10-4 mol/L之间有很好的线性关系(R为0.996),检出限为5.0×10-8mol/L。电极已初步用于实际样品中BPA的测定。     

Three-element doped carbon dots for the detection of p-nitrophenolEI北大核心CSCD

Based on the characteristics that heteroatom doping can improve the luminescence performance of carbon dotsa new type of three-element co-doped carbon dots NSSi-CDswas prepared. The synthesis conditions were optimizedand the morphologystructure and luminescence properties of NSSi-CDs were characterized. NSSi-CDs can emit 450 nm blue fluorescence under excitation at 370 nmand the fluorescence quantum yield reached 11%. The study found that p-nitrophenol PNPhas a strong fluorescence quenching effect on NSSi-CDsand thus a new method for the determination of PNP with NSSi-CDs fluorescent probe was constructed. When the concentration of PNP was in the range of 0.9-60 μµmol/Lit had a good linear relationship with the fluorescence quenching efficiencyF0 /Fand the detection limit was 0.36 μµmol/L. This method was used to determine PNP in actual water samples with good recoveries of 90.6%-95.2%. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

A nonenzyme glucose sensor based on Cu/Ni/CMWCNTs nanocompositesEI北大核心CSCD

Copper-nickel bimetallic nanoparticles decorated on carboxylated multi-walled carbon nanotubes （Cu/Ni/CMWCNTs）were prepared by using a simple one-pot solvothermal method,which was then employed to construct a highly sensitive non-enzymatic glucose sensor. The modified electrode showed high sensitivity and stability in glucose detection,which was mainly attributed to the synergistic effect of the compact copper-nickel nanocomposite and carboxylated multi-walled carbon nanotubes that possessing high specific surface area to increase the number of active sites and to improve the electrocatalytic activity of the modified electrode. The phase structure and morphology of the material were characterized by X-ray diffraction and scanning electron microscope; the electrochemical performance of the sensor was studied by cyclic voltammetry and chronoamperometry. The sensor had a sensitivity of 1949.1 μµA·L/（mmol·cm2）for glucose detection in the linear range of 1.0-8000 μµmol/L at a potential of 0.55 V,and the detection limit was 0.2 μµmol/L. The sensor was also applied to measure the concentration of glucose in serum samples. The developed nanocomposites sensor has the potential prospect to monitor blood glucose. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

N-doped peanut membrane carbon quantum dots as a off-on fluorescence probe determination of hydroquinoneEI北大核心CSCD

N-doped peanut membrane carbon quantum dots (N-CQDs) were prepared by one-step hydrothermal method using peanut membrane and urea as materials. On the basis of investigating the spectral characteristics of the N-CQDs, we found that KMnO4 could cause the fluorescence signal of the N-CQDs to turn-off in the B-R buffer system with pH 10. 38. Once hydroquinone was added, the fluorescence signal of the N-CQDs-KMnO4 system gradually recovered and the fluorescence signal turned on. Based on this, a new off-on fluorescence probe method for the detection of hydroquinone-N-CQDs-KMnO4 system was developed. Under the optimized conditions, the recovered fluorescence of N-CQDs was linearly related with the hydroquinone concentration in the range of 0. 10-200 mmol / L, the linear equation was ΔF = 1. 6819c + 153. 84 (r = 0. 9992), with the detection limit of 30 μmol / L. The method has been successfully applied to the determination of hydroquinone in simulated samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Surface-imprinted core–shell Au nanoparticles for selective detection of bisphenol A based on surface-enhanced Raman scattering

Surface-imprinted core–shell Au nanoparticles (AuNPs) were explored for the highly selective detection of bisphenol A (BPA) by surface-enhanced Raman scattering (SERS). A triethoxysilane-template complex (BPA-Si) was synthesized and then utilized to fabricate a molecularly imprinted polymer (MIP) layer on the AuNPs via a sol–gel process. The imprinted BPA molecules were removed by a simple thermal treatment to generated the imprint-removed material, MIP-ir-AuNPs, with the desired recognition sites that could selectively rebind the BPA molecules. The morphological and polymeric characteristics of MIP-ir-AuNPs were investigated by transmission electron microscopy and Fourier-transform infrared spectroscopy. The results demonstrated that the MIP-ir-AuNPs were fabricated with a 2 nm MIP shell layer within which abundant amine groups were generated. The rebinding kinetics study showed that the MIP-ir-AuNPs could reach the equilibrium adsorption for BPA within 10 min owning to the advantage of ultrathin core–shell nanostructure. Moreover, a linear relationship between SERS intensity and the concentration of BPA on the MIP-ir-AuNPs was observed in the range of 0.5–22.8 mg L⁻¹, with a detection limit of 0.12 mg L⁻¹ (blank ± 3 × s.d.). When applied to SERS detection, the developed surface-imprinted core–shell MIP-ir-AuNPs could recognize BPA and prevent interference from the structural analogues such as hexafluorobisphenol A (BPAF) and diethylstilbestrol (DES). These results revealed that the proposed method displayed significant potential utility in rapid and selective detection of BPA in real samples.     

Pd nanoparticles on boron doped graphene catalyst for electrochemical detection of hydrogen peroxide prepared by electroless deposition methodEI北大核心CSCD

Taking advantage of large conjugated structure and reductivity of boron-doped graphenethe palladium nanoparticles/boron-doped graphene catalyst was prepared by electroless deposition method using boron-doped graphene as reductant and stabilizer. The average size of palladium nanoparticles highly dispersed on the surface of boron-doped graphene was about 6.5 nm. The electrochemical sensor was prepared by modifying the as-formed catalyst on the surface of glassy carbon electrode. The obtained electrochemical sensor exhibited an excellent electrochemical catalytic activity for H2 O2 . It exhibited high sensitivity with the detection limit as low as 830 nmol/L and good linearity in the range of 2.5-300 μµmol/L for detection of H2 O2 . It could be utilized for the determination of H2 O2 in milk samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

构建基于rGO/AuNPs的电化学检测平台及其在双酚A检测中的应用研究

本实验以电沉积法和滴涂法制备还原氧化石墨/金纳米颗粒(rGO/AuNPs)电化学传感器用于BPA的痕量测定。首先以GO为原料,以维生素C为还原剂,一步法合成rGO。对合成材料进行扫描电镜、X射线衍射、紫外可见吸收光谱和傅里叶红外变换光谱的表征。采用IT计时电流电位法将纳米金粒子沉积于玻碳电极(GCE)表面,然后将rGO滴涂于AuNPs修饰的玻碳电极表面,依次采用循环伏安法和交流阻抗谱法对制备的传感器进行表征。探讨了不同因素对实验结果的影响,在优化实验条件下,当BPA浓度在10～400μmol·L^-1时,其浓度与峰值电流具有很好的线性关系,检出限低至1.9×10^-7 mol·L^-1(S/N=3),样品的平均加标回收率在97.6%～102.4%之间。     

Rapid detection of chlorpheniramine maleate by an electrochemical sensor based on metal-organic frameworks CHP@Cu3（BTC）2 /MWCNTsEI北大核心CSCD

Copper hydroxyphosphate@metal-organic frameworks/multi-wall carbon nanotube composites （CHP@Cu3 （BTC）2 /MWCNTs）were prepared by a new in-situ template method and then an electrochemical sensor was developed based on the composites. The crystal structure and morphology of the material were characterized by X-ray diffraction and scanning electron microscope. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical catalytic performance,and the determination conditions were optimized. The rapid and sensitive detection of chlorphenamine maleate was realized. There was a good linear relationship between the oxidation peak current and concentration of chlorphenamine maleate in the ranges from 5 to 100 µμmol/L and from 150 to 800 µμmol/L,and the linear equations were as Ipa （µμA）=0.1559c（µμmol/L）-0.3533 （R2 =0.9973）and Ipa （µμA）=0.02328c（µμmol/L）+16.63（R2 =0.9594）,and the detection limit was 1.67 µμmol/L. The recoveries of the actual drug ranged from 91.0% to 109.1%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Research progress of rapid detection of typical environmental pollutants based on chromatographic technologiesEI北大核心CSCD

对复杂环境介质中的典型污染物进行快速、精准甚至远程连续自动的检测,是控制环境污染、确保环境和生态安全的重要前提。近年来,基于色谱技术的典型环境污染物快速检测方法发展迅猛,主要包括样品快速制备和目标物快速检测两方面。辅助萃取、快速液相萃取、QuEChERS等样品前处理方法具有萃取效率高、溶剂消耗少、操作简便快速等优点。快速检测技术可在几秒到半小时内提供检测结果,主要包括实验室和现场检测。本文综述了2019年以来基于色谱技术的典型环境污染物快速检测研究新进展。介绍了萃取技术和基于试验设计的样品快速制备,实验室快速检测、便携仪器现场检测及遥感技术远程检测,提出了色谱技术快速检测环境污染物的挑战和展望。     

Construction and application of carbon nanotube/polypyrrole-based bacterial surface imprinted sensorEI北大核心CSCD

A simple and fast "non-hole" bacteria surface imprinted (SPBIP) impedance sensor was constructed for ultrasensitive detection of Salmonella. The SPBIP sensor was prepared by one step electropolymerization of pyrrole (functional monomer), single-walled carbon nanotube (SWNT, nano-modulator), and Salmonella(template) onto a glassy carbon electrode. After removing the bacterial template, "non-hole" imprinted sites were formed on the surface of the polymer matrix, allowing the target bacteria to be specifically recognized. The resulting changes in the electrode surface impedance could be used to detect the target bacteria. The effects of the amount of SWNT, polymerization cycles, eluents, elution time and recognition time on the recognition ability of the sensor were investigated. Under the optimal conditions, the sensor could be used to detect 10~1×107 CFU/mLSalmonella with the limit of detection of 3.5 CFU/mL. The sensor could be used for the detection of salmonella in drinking water and orange juice samples with the recoveries ranging from 95.4% to 109.5%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

基于多壁碳纳米管和聚十六烷基三甲基溴化铵修饰玻碳电极的电化学法快速测定水和土壤中双酚A的含量北大核心CSCD

基于多壁碳纳米管(MWCNTs)和聚十六烷基三甲基溴化铵(p-CTAB)的高导电性、高增敏性,制备了MWCNTs、p-CTAB修饰的玻碳电极(GCE),将其作为工作电极(MWCNTs/p-CTAB/GCE),用于快速测定水和土壤中双酚A(BPA)的含量。以GCE为工作电极,采用循环伏安法(CV)对0.5 g·L^(-1) CTAB溶液扫描20圈,得到p-CTAB修饰的GCE(p-CTAB/GCE);吸取1.96 g·L^(-1) MWCNTs标准溶液5μL,滴涂在p-CTAB/GCE表面,干燥后得到MWCNTs/p-CTAB/GCE。水样经过滤,分取2 mL与0.3 mol·L^(-1)磷酸盐缓冲溶液(pH 7.0)8 mL混匀后待测;土壤样品25 g经风干、研磨、过筛后,用乙醇50 mL提取两次,浓缩至约1 mL,用无水乙醇定容至10 mL,分取2 mL与0.3 mol·L^(-1)磷酸盐缓冲溶液(pH 7.0)8 mL混匀后待测。以MWCNTs/p-CTAB/GCE为工作电极,钛棒为对电极,饱和甘汞电极为参比电极,设置搅拌速率为800 r·min^(-1),于0.2 V富集待测样品溶液中的BPA 150 s,采用差分脉冲伏安法(DPV)测定BPA的含量。扫描电子显微镜表征结果显示,MWCNTs/p-CTAB/GCE表面呈多孔空隙和多孔网状结构。以DPV、CV和电化学阻抗谱法考察了BPA在MWCNTs/p-CTAB/GCE上的电化学行为,结果表明BPA在该电极上的电化学氧化反应是一个受吸附控制的不可逆反应,BPA的浓度在0.08~20μmol·L^(-1)内与其对应的氧化峰电流呈线性关系,检出限为0.02μmol·L^(-1)。用同一支MWCNTs/p-CTAB/GCE重复测定BPA标准溶液10次,测定值的相对标准偏差为5.0%。对实际样品进行加标回收试验,BPA的回收率为82.0%~106%,测定值的相对标准偏差(n=5)为1.6%~8.1%。     

Preparation and application of surface enhanced Raman scattering substrate synthesized from single walled carbon nanotubes and silver nanoparticlesEI北大核心CSCD

By hydrothermal synthesis, silver nanoparticles (AgNPs) arranged on single-walled carbon nanotubes (SWCNTs) uniformly, and a SiO2/CNTs/AgNPs surface enhanced Raman scattering (SERS) substrate with composite open structure was prepared. The synthesized SiO2/CNTs/AgNPs were characterized by transmission electron microscopy (TEM. Using rhodamine 6G(R6G) as the probe molecule, the enhancement factor (EF) was 1.23×108, and the standard deviation was 2.31. Taking the phenol red, a common water pollutant, as the practical sample, the concentration of phenol red in the range of 1×10-4 -1×10-10 mol/L had a great exponential fitting relationship with its Raman signal intensity at 1153 cm-1 and 1441 cm-1, and the correlation coefficient (R2) was 0.99991. The substrate can realize the qualitative and quantitative detection of practical samples. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Electrochemical determination of quercetin by self-assembled platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene) nanocomposite modified glassy carbon electrode

A simple and sensitive platinum nanoparticles/poly(hydroxymethylated-3,4-ethylenedioxylthiophene)nanocomposite(PtNPs/PEDOT-MeOH) modified glassy carbon electrode(GCE) was successfully developed for the electrochemical determination of quercetin.Scanning electron microscopy and energy dispersive X-ray spectroscopy results indicated that the PtNPs were inserted into the PEDOTMeOH layer.Compared with the bare GCE and poly(3,4-ethylenedioxythiophene)(PEDOT) electrodes,the PtNPs/PEDOT-MeOH/GCE modified electrode exhibited a higher electrocatalytic ability toward the oxidation of quercetin due to the synergic effects of the electrocatalytic activity and strong adsorption ability of PtNPs together with the good water solubility and high conductivity of PEDOT-MeOH.The electrochemical sensor can be applied to the quantification of quercetin with a linear range covering0.04-91 μmol L~(-1) and a low detection limit of 5.2 nmol L~(-1).Furthermore,the modified electrode also exhibited good reproducibility and long-term stability,as well as high selectivity.     

An electrochemical aptasensor based on cu2+-induced signal amplification strategy for the detection of ochratoxin aEI北大核心CSCD

A novel electrochemical aptasensor based on a Cu2+-induced signal amplification strategy was constructed for the rapid, sensitive and specific detection of ochratoxin A （OTA）. The OTA aptamer with poly （T） was hybridized with the captured DNA probe on the electrode surface. In the presence of Cu2+ and ascorbic acid, the end of poly（T） was used as a template to in situ grow copper nanoclusters （Cu NCs）. In the absence of targeted OTA, the gold electrodes after decorating Cu NCs were immersed into an acidic environment to release Cu2+. After enriching Cu2+ at a potential of − 1.6 V, the strongest current value of copper was recorded by measuring differential pulse voltammetry （DPV）. In the presence of OTA, the OTA aptamer was tightly bound to the target OTA. The OTA aptamer broke away from the electrode to reduce the growth of Cu NCs, resulting in lower DPV current response. This proposed method was employed to detect OTA with linear range from 0.1 to 50.0 ng/mL, and the detection limit was 41.2 pg/mL. The Cu2+-induced electrochemical aptasensor can be further applied in the analysis of target OTA in coffee solution samples. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

L-cysteine modified gold nanoparticles / paper chip system for rapid detection of chiral dopaEI北大核心CSCD

A new detection method for L-Dopa based on paper chips was established. The L-Cys-AuNPs were characterized by their size, zeta potential, and UV-visible absorption spectra. The system had the high selectivity for the colorimetric detection of L-Dopa with the color changing from red to blue. The results were recorded using a common cell phone and subsequently analyzed using Photoshop software. A ratiometric color intensity method was designed for the quantification analysis. The ratio of color intensity at red channel and blue channel (R / B) increases linearly with L-Dopa concentration in the range of 5 to 80 μmol / L (R = 0. 9944), with the limit of detection of 4 μmol / L. The spiked recoveries of samples were 98%-102%. The RSDs of inter-day and intraday were 3. 3% and 3. 8%, respectively. Real samples were detected, and the error between the determination and the labeled value was within 5%. The method can be used to detect L-Dopa in real samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Colorimetric and fluorescence dual-mode detection of arsenic（v） based on cobalt oxyhydroxide nanoplatesEI北大核心CSCD

The oxidase-like activity of cobalt oxyhydroxide （CoOOH） nanosheets is inhibited by arsenic （V） in the system, thereby attenuating the oxidation of p-phenylenediamine （PPD） by CoOOH nanosheets, and changing the absorbance of the solution. Based on this principle, and the fluorescence inner filter effect （IFE） of p-phenylenediamine oxide （oxPPD） on the dye acridine orange （AO）, a colorimetric and fluorescence dualmode method for the quantitative detection of As（V） was established. The variation of absorbance and fluorescence intensity of As（V） with different concentrations was investigated, and the effects of the concentrations of CoOOH nanosheet and PPD, pH of buffer solution, and temperature of reaction were optimized. The results showed that under the optimized conditions, the concentration of As（Ⅴ） had a good linear relationship with the corresponding signal intensity, and the detection limits of colorimetric and fluorescence method were 5 and 10 nmol/L, respectively. The method has been used for the determination of arsenic（V） in lake water located the city center. © 2023, Youke Publishing Co.,Ltd. All rights reserved.