摘要：
A novel catalyst of FeCo nanoparticles (FeCo NPs) incorporated porous nanocages (FeCo NPs@PNC) was first synthesized by encapsulating of FeCo alloy into ZIF-8 and further carbonation of the composite. The FeCo NPs@PNC displays enhanced intrinsic oxidase-like activity compared to the individual FeCo NPs and porous nanocages (PNC). The FeCo NPs@PNC can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to oxidized TMB (oxTMB) without H2O2, producing a blue color with a maximum absorption peak at 652nm. The catalytic mechanism was investigated and it found that the intermediate (O2(.-)) produced from the catalytic process in the system of TMB-O2-FeCo NPs@PNC can accelerate the oxidation of TMB to oxTMB. However, ascorbic acid (AA) can reduce the oxTMB and result in a conspicuous blue color fading. Therefore, a novel colorimetric platform was constructed to quantify AA with the linear range of 0.5-28muM and detection limit of 0.38muM (at 3sigma/m). Owing to the alkaline phosphatase (ALP) can catalyze the hydrolysis of AA 2-phosphate (AAP) into AA, ALP can also be quantified by the above method. And the linear range for ALP is 0.6-10 U L(-1) and the limit of detection is 0.49 U L(-1). The FeCo NPs@PNC also shows excellent stability and reproducibility. This study provides a new alternative oxidase mimetic on the basis of easily obtained metal-organic frameworks derivatives to replace the expensive natural enzymes and noble metal based nanoenzymes, which will show great potential in biological assays.
作者机构：
[Zhang, Youyu; Wu, Tengteng; Ma, Zhangyan; Liu, Meiling; Hou, Wenli; Yao, Shouzhuo] Hunan Normal Univ, Coll Chem & Chem Engn, Minist Educ, Key Lab Chem Biol & Tradit Chinese Med Res, Changsha 410081, Hunan, Peoples R China.;[Liu, Xiaoying] Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.
通讯机构：
[Liu, Meiling; Liu, Xiaoying] H;Hunan Normal Univ, Coll Chem & Chem Engn, Minist Educ, Key Lab Chem Biol & Tradit Chinese Med Res, Changsha 410081, Hunan, Peoples R China.;Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.
关键词：
*3,3,5,5-Tetramethylbenzidine;*Colorimetric assay;*Enzyme mimic;*Inhibition;*Nanocubes;*Peroxidase mimetic;*Prussian White
摘要：
Colorimetric methods are described for the determination of ascorbic acid (AA) and alkaline phosphatase (ALP). Both assays are based on the inhibition of the peroxidase (POx)-like activity of Prussian Blue nanocubes (PB NCs) capped with citric acid. They catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to produce a blue color with an absorption maximum at 652 nm. On addition of AA, the PB NCs are reduced to Prussian White (PW) which does not act as a POx mimic. This results in a decreased rate of the formation of the blue coloration whose intensity decreases with increasing concentration of AA. The assay allows AA to be quantified with a 35 nM detection limit (at 3sigma/m). The hydrolysis of AA phosphate by ALP leads to the formation of AA which can be quantified by the above method. Based on this, the activity of ALP can be determined by measurement of the intensity of the blue coloration thus formed. The method can be used to determine the activity of ALP with a detection limit as low as 0.23 U.L(-1). Graphical abstract Schematic presentation of a method for colorimetric determination of ALP activity. AA obtained by ALP-catalyzed hydrolysis of ascorbic acid phosphate (AAP) inhibits the intrinsic peroxidase-like activity of PB NCs by reducing Prussian Blue nanocrystals (PB NCs) to form inactive Prussian White (PW).
期刊：
Sensors and Actuators B-Chemical,2018年270:530-537 ISSN：0925-4005
通讯作者：
Liu, Xiaoying;Zhao, Peng
作者机构：
[Liu, Xiaoying; Peng, Chang; Zhang, Wei; Zhou, Suya; Zhang, Xuemei; Zeng, Tianqin] Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.;[Li, Hongmei; Zhao, Peng] Southern Med Univ, Sch Pharmaceut Sci, Guangzhou Key Lab Drug Res Emerging Virus Prevent, Guangdong Prov Key Lab New Drug Screening, 1838 Guangzhou Ave North, Guangzhou 510515, Guangdong, Peoples R China.
通讯机构：
[Liu, Xiaoying] H;[Zhao, Peng] S;Hunan Agr Univ, Coll Sci, Changsha 410128, Hunan, Peoples R China.;Southern Med Univ, Sch Pharmaceut Sci, Guangzhou Key Lab Drug Res Emerging Virus Prevent, Guangdong Prov Key Lab New Drug Screening, 1838 Guangzhou Ave North, Guangzhou 510515, Guangdong, Peoples R China.
关键词：
N-doped hollow carbon spheres;One pot synthesis;Electrical catalyst;H2O2;Human serum samples
摘要：
N-doped hollow carbon spheres (N-HCS) have been proved as efficient electrical catalytic materials with outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) ability. However, conventional approaches for the synthesis of N-HCS always involved multistep procedures. In this paper, by appropriately controlling the polymerization oft etraethoxysilane (TEOS) and resorcinol/formaldehyde (RF), N-HCS have been synthesized through "one pot" method without use of surfactant. Next, the ORR and OER of N-HCS were conducted to examine its electrocatalytic ability. Finally, it was modified on the glassy carbon electrode (GCE) as an improved electrical catalyst to monitor H2O2 in human serum samples. The linear ranges for monitoring H2O2 were from 0.05 mM to 29.5 mM and from 29.5 mM to 47.5 mM with a limit of detection of 0.02 mM. The recoveries for the assays in human serums were between 92.5% and 107.4%. Therefore, we believe that this newly synthesized N-HCS will play a significant role in the synthesis and application of electrocatalytic materials and the development of novel electrochemical sensors.
摘要：
Electron mediators have the ability to facilitate electron acceptance and donation, which can accelerate the electron transfer during the electrochemical process. Few research has been reported about electroactive polymer nanospheres as redox mediators for sensing to date. In this study, we synthesized a new electroactive ferrocene derivative polymer nanospheres (FPS) via a facile and self-assembly method. The obtained FPS was characterized by UV-Vis spectra, Fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. Based on the electroactive property of FPS, a new electrochemical sensor for acetaminophen (AP) based on the nanocomposite of multi-walled carbon nanotubes-ploy-diallyl-dimethyl-ammonium chloride-FPS (MWCNT-PDDA-FPS) was firstly developed. The greatly enhanced electrochemical performance towards AP determination can be obtained owing to the electrocatalysis of electroactive FPS and good conductivity of MWCNT. The AP sensor exhibits a wide sensing linear range from 3 to 1100 mu M and the detection limit is 0.6 mu M(S/N = 3). Therefore, these ferrocene derivative polymer nanospheres may become a new nanomaterial to construct of platforms for bioanalytical and electrochemical immune research in the future. (C) 2018 Elsevier Ltd. All rights reserved.
摘要：
A simple and efficient eletrochemical sensing platform for simultaneous detection of hydroquinone (HQ), catechol (CC) and resorcinol (RC) based on the Au-Pd bimetallic and graphene is described in this paper. The Au-Pd reduced graphene oxide (Au-Pd NF/rGO) was prepared by the electrochemical co-reduction deposition via cyclic voltammetry method (CV). The Au-Pd NF/rGO nanocomposite was examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and electrochemical methods CV and differential pulse voltammety (DPV) study showed that the three dihydroxybenzene isomers can be catalytically oxidized and discriminated simultaneously on the Au-Pd NF/rGO/GCE. The presence of Pd makes the performance of the sensor superior to that of in the absence of it. Owing to the integrated superior conductivity and excellent catalytic property of Au-Pd NF/rGO, the sensitive and simultaneous detection of HQ, CC and RC was realized in the individual or triple-components solution based on the as proposed Au-Pd NF/rGO/GCE, which shows wide linear range and low detection limit. The detection of them in tap water, river water and lake water were also successfully performed and good recovery was obtained. (C) 2017 Elsevier Ltd. All rights reserved.
摘要：
<jats:title>Abstract</jats:title><jats:p>A thiolated catechol (CA) consisting of 1,6‐Hexanedithiol (HDT) and CA was modified on a gold (Au) electrode to obtain an amperometric <jats:italic>L</jats:italic>‐cysteine sensor with detection limit of 60.6 nM. The preparation of thiolated CA was conducted via a thiol addition between HDT and electro‐oxidized CA (EOCA). Briefly, the thiol addition reaction was accomplished by potential cycling of HDT/Au electrode in 0.1 M phosphate buffer (PB, pH 7.2) containing CA, and an EOCA‐HDT/Au electrode was produced. The obtained EOCA‐HDT/Au electrode exhibits a pair of well‐defined redox peaks (at 0.22/0.10 V) of <jats:italic>o</jats:italic>‐quinone moiety, which effectively mediates the oxidation of <jats:italic>L</jats:italic>‐cysteine in a 0.1 M PB (pH 7.2), with an over‐potential decrease by ca. 0.12 V (versus bare Au electrode). Electrochemical quartz crystal microbalance, cyclic voltammetry and surface‐enhanced Raman spectra were used to study relevant processes and/or film properties. The amperometric <jats:italic>L</jats:italic>‐cysteine sensor has good anti‐interferent ability and reproducibility. It also has acceptable recovery for detection of <jats:italic>L</jats:italic>‐cysteine in urine samples.</jats:p>
摘要：
In this paper, a new multifunctional electrochemical platform for hydrogen peroxide (H2O2) and nitrite (NO2) based on silver/carbon nano-composite (Ag/C NC) was firstly proposed. Ag/C NC was synthesized by using carbon dots (C-dots) as the reductant by a facile one-step synthesis method and confirmed by UV-Vis, Fourier transforms infrared spectroscopy, transmission electron microscopy, scanning electron microscopy and dynamic light scattering. The Ag/C NC based electrodes showed excellent electrocatalytic activity toward the reduction of H2O2 and the oxidation of NO2. When Ag/C NC was dropped on the bare GCE, the electrocatalytic reduction of H2O2 occurred and showed wide linear range from 5.00 mu M to 11.05 mu M with the detection limit of 0.51 mu M. When Ag/C NC was dropped on graphene (GR) modified electrode, the Ag/C NC/GR/GCE showed extremely fast direct electron transfer and good electrocatalytic activity toward oxidation of nitrite. It showed wide linear range from 4.00 mu M to 2.00 mu M with the detection limit of 0.48 mu M. The Ag/C NC/GR/GCE was successfully applied in analysis of nitrite in real samples and gained good testing recovery. Therefore, the proposed electrochemical sensors for H2O2 and NO2 exhibited many advantages, such as operational simplicity, rapid responses, good reproducibility and stability, and can be simply tuned to utilize for electrochemical detection of H2O2 and NO2. This study will open a facial and simple synthesis method for preparing carbon based noble metal nanocomposite and utilizes them in detection for different purposes, which may provide new opportunity and prospect in the field of electrochemical biosensing. (C) 2016 Elsevier Ltd. All rights reserved.
