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Mikrochimica Acta

Chaoqiao Liu, Jianzhi Huang, Lishi Wang
The authors describe a method for electrochemical synthesis of a nanocomposite consisting of carboxylated multi-walled carbon nanotubes, polythionine and platinum nanoparticles (denoted as cMWCNT@pTh@Pt). The composite was placed on a glassy carbon electrode (GCE) to obtain a sensor for simultaneous determination of myricetin and rutin by differential pulse voltammetry, with typical peak voltages of 0.16 and 0.34 V (vs. SCE). Under optimal conditions, the modified GCE has a linear response in the range of 0...
August 16, 2018: Mikrochimica Acta
Karen Yasmim Pereira Dos Santos Avelino, Isaac Aarón Morales Frías, Norma Lucena-Silva, César Augusto Souza de Andrade, Maria Danielly Lima de Oliveira
A label-free impedimetric biosensor was developed for determination of BCR/ABL transcripts. Specific DNA primers were covalently immobilized on a gold electrode modified with carboxylated multiwalled carbon nanotubes (cMWCNTs) and zinc oxide nanoparticles (ZnO-NPs). Aggregation of the ZnO-NPs is prevented by the introduction of an amino-modified silica coating, which also allows a subsequent covalent linkage to cMWCNTs. The impedimetric biosensor was typically operated at a working voltage of +10 mV vs. Ag/AgCl, in a frequency range from 100 mHz to 100 kHz...
August 16, 2018: Mikrochimica Acta
Zina Fredj, MounirBen Ali, Baljit Singh, Eithne Dempsey
The authors describe a method for simultaneous voltammetric determination of 5-hydroxytryptamine (serotonin; 5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA). A glassy carbon electrode was modified with poly(pyrrole-3-carboxylic acid) and with platinised carbon nanofibers to obtain a sensor that can quantify 5-HT and 5-HIAA with detection limits of 10 nM and 20 nM, respectively. The peak currents, best measured at voltages of 170 mV and 500 mV (vs. Ag/AgCl) for 5-HT and 5-HIAA, increase linearly in the 0...
August 13, 2018: Mikrochimica Acta
Na Liu, Kai Xu, Liquan Liu, Xin Chen, Yufan Zou, Xianjin Xiao
A star-shaped fluorescent DNA probe (S-probe) is described that can recognize target DNA and discriminate it from interfering DNA via strand displacement including branch migration and toehold exchange. The artificially designed S-probe does not harm the strand displacement while it allows the fluorescently labelled strand and the quencher-labelled strand to be shared among different S-probes targeting different genetic variations. Generally, multiplexed detection of different MT/WT pairs requires different fluorophore-labelled and quencher-labelled strands...
August 13, 2018: Mikrochimica Acta
Karunagaran Selvarani, Amrutha Prabhakaran, Palaniappan Arumugam, Sheela Berchmans, Pranati Nayak
Delaminated 2D sheets of MoSe2 were prepared by liquid phase exfoliation and were embedded over high surface area hydrogen exfoliated graphene (HEG) by a simple technique. The MoSe2 /HEG hybrid composite exhibits fast heterogeneous electron-transfer (HET) and a high electrochemically active surface area compared to only HEG. When employed for detection of NADH, it exhibits electrooxidation at a low potential of 150 mV (vs. Ag/AgCl) with high sensitivity of 0.0814 µA⋅µM-1 ⋅cm2 over a wide linear range (1-280 μM), good selectivity, and a low limit of detection (1 μM)...
August 11, 2018: Mikrochimica Acta
Jing Wang, Haigang Li, Tingting Li, Liansheng Ling
A one-step, one-tube colorimetric assay is described for the detection of bacterial double-stranded DNA (dsDNA). It utilizes a G-quadruplex DNAzyme produced by an asymmetric polymerase chain reaction (As-PCR) that catalyzes the oxidation of cysteine to form cystine. This results in the formation of oligonucleotide-modified gold nanoparticles via triplex formation, and eventually in a color change from red to blue that occurs within about 10 mins. This can be measured by ratiometric colorimetric (at 525 and 600 nm)...
August 11, 2018: Mikrochimica Acta
Titilope John Jayeoye, Wilairat Cheewasedtham, Chatchai Putson, Thitima Rujiralai
The authors describe a rapid, sensitive and selective colorimetric assay for sialic acid (SA) based on the use of gold nanoparticles (AuNPs) modified with 3-aminophenylboronic acid (3-APBA) which acts as the recognition probe for SA. 3-APBA contains amino groups and boronic acid groups through which it can assemble on citrate stabilized AuNPs. It reacts with the cis-diol groups of SA by reversible formation of a cyclic boronate ester in slightly acidic buffer. Detection involves the sequential addition of AuNPs, phosphate buffer, 3-APBA and SA in a tube, vortex mixing, acquisition of photographic images or absorption spectra, and calculation of the result...
August 10, 2018: Mikrochimica Acta
Jing Peng, Tao He, Yulian Sun, Yawen Liu, Qianqian Cao, Qiong Wang, Hao Tang
A method is described for the determination of microRNA. It is based on the use of organic electrochemical transistors (OECTs) fabricated on a flexible poly(ethylene terephthalate) substrate. A gold electrode was modified with gold nanoparticles to immobilize the capture DNA probe and then served as the gate of the device. The detection of microRNA21 was realized by monitoring the change of the drain-source current after hybridization of capture DNA with microRNA21. Under optimal conditions, this biosensor exhibits good sensitivity and specificity...
August 10, 2018: Mikrochimica Acta
Bei Qin, Kuan Yang
A sensitive electrochemical aptasensor was developed for the determination of thrombin. It is based on signal amplification by using graphene oxide (GO) decorated with silver nanoparticles (AgNP) and placed on a microelectrode. The graphene oxide decorated with silver nanoparticles (AgNP-GO) was synthesized by chemical reduction and then modified with a thrombin-binding aptamer 1 (TBA1; a 29-mer) carrying a 3'-terminal thiol group. It was immobilized on the AgNP-GO by self-assembled monolayer technique to form the signaling probe (TBA1-AgNP-GO)...
August 9, 2018: Mikrochimica Acta
Samira Yazdanparast, Ali Benvidi, Maryam Banaei, Habib Nikukar, Marzieh Dehghan Tezerjani, Mostafa Azimzadeh
This paper reports on a sensitive and selective method for the detection of Michigan Cancer Foundation-7 (MCF-7) human breast cancer cells and MUC1 biomarker by using an aptamer-based sandwich assay. A biocompatible nanocomposite consisting of multiwall carbon nanotubes (MWCNT) and poly(glutamic acid) is placed on a glassy carbon electrode (GCE). The sandwich assay relies on the use of a mucin 1 (MUC1)-binding aptamer that is first immobilized on the surface of modified GCE. Another aptamer (labeled with silver nanoparticles) is applied for secondary recognition of MCF-7 cells in order to increase selectivity and produce an amplified signal...
August 9, 2018: Mikrochimica Acta
Ebrahim Naghian, Mostafa Najafi
Several nanocomposites of tin oxide with CuS, SnS or Cu@SnS were prepared and used to modify carbon paste electrodes (CPEs). The structure and morphology of the materials were studied by XRD and SEM techniques. Cyclic voltammetry and electrochemical impedance spectroscopy were applied to investigate their electrochemical properties. The modified CPEs exhibit superior voltammetric response to paracetamol (PAT) and hydroquinone (HQ) (when compared to a bare CPE) in terms of onset oxidation potential and current density...
August 9, 2018: Mikrochimica Acta
Wei Sheng, Qing Chang, Yingjie Shi, Wenxia Duan, Yan Zhang, Shuo Wang
A fluorometric immunochromatographic assay (FICA) is described where ZnCdSe/ZnS quantum dots (QDs) act as fluorescent label and gold nanoparticles (AuNPs) act as quencher. The assay works in the "turn-on" mode, i.e. the fluorescent signal (best measured at excitation/emission wavelengths of 302/525 nm) increases with the increase of analyte concentration. This assay can detect tetracycline antibiotics including tetracycline, oxytetracycline, chlortetracycline, and doxycycline. It is not interfered by other veterinary drugs...
August 7, 2018: Mikrochimica Acta
Mohammed Awad Abedalwafa, Yan Li, De Li, Noor Sanbhal, Jianmao Yang, Lu Wang
The authors describe colorimetric test strips by using electrospun nanofiber membranes (NFMs) carrying gold/silver core/shell nanoparticles (Au/Ag NPs). The Au/Ag NPs were immobilized on aminated porous polyacrylonitrile NFMs to obtain test strips with a tortuous porous structure and a large surface area (38.6 m2  g-1 ). The color of the resultant NFMs, measured at a wavelength of 420 nm, is red-shifted when exposed to copper ions (Cu2+ ) with a color change from yellow to pink to colorless. The effect is due to leaching Au/Ag NPs from the NFMs in the presence of ammonium chloride, thiosulfate and Cu2+ upon which soluble thiosulfate complexes of Ag+ , Au3+ and Cu2+ are formed...
August 6, 2018: Mikrochimica Acta
Xiaolu Yan, Jing Sun, Xian-En Zhao, Renjun Wang, Xiao Wang, Ya-Nan Zuo, Wei Liu, Rongmei Kong, Shuyun Zhu
The authors describe a molecular beacon-based fluorescent probe for the determination of the cancer drug bleomycin (BLM). The probe was tagged with DNA-templated silver nanoclusters (DNA-AgNCs) and guanine-rich sequences (GRSs) at two terminals serving as signal reporter with a loop. In the absence of the BLM-iron(II) complex [BLM-Fe(II)], the probe has a hairpin shape and displays strong fluorescence because the AgNCs are close to the GRSs. In the presence of the BLM-Fe(II) complex, it will selectively cleave the probe at the 5'-GC-3' scission site of the loop...
August 6, 2018: Mikrochimica Acta
Yang Peng, Huawei Shen, Sitian Tang, Zhenglan Huang, Yixiong Hao, Zhenhong Luo, Fangzhu Zhou, Teng Wang, Wenli Feng
A colorimetric assay is described for the detection of BCR/ABL fusion genes. Polyamidoamine (PAMAM) dendrimers were placed on peroxidase (POx) mimicking Au@Pt nanoparticles to form a nanocomposite of type Au@Pt-PAMAM. Capture DNA probe is a designed nucleic acid strand that specifically binds target DNA to the surface of the electrode. The capture probe was attached to magnetic beads via biotin and avidin interaction. The hairpin structure of the capture probe can only be opened by the complementary BCR/ABL DNA...
August 4, 2018: Mikrochimica Acta
Hao-Hua Deng, Kai-Yuan Huang, Qiong-Qiong Zhuang, Quan-Quan Zhuang, Hua-Ping Peng, Yin-Huan Liu, Xing-Hua Xia, Wei Chen
Water-soluble and non-aggregating gold nanoclusters (AuNCs) were obtained by modification of the AuNCs with dithiothreitol (DTT) and then coating them with carboxylated chitosan. This process remarkably enhances the dispersibility of DTT-coated AuNCs in water. The resulting AuNCs, on photoexcitation at 285 nm, display strong red emission with a maximum at 650 nm and a 23% quantum yield. Fluorescence is strongly and selectively suppressed in the presence of 6-mercaptopurine (6-MP). Photoluminescence drops linearly in the 0...
August 3, 2018: Mikrochimica Acta
Rinky Sha, Nandimalla Vishnu, Sushmee Badhulika
The authors report on a composite based electrocatalyst for methanol oxidation and H2 O2 sensing. The composite consists of Pt nanoparticles (NPs), Pd nanoflakes, and MoS2 . It was synthesized by chemical reduction followed by template-free electro-deposition of Pt NPs. FESEM images of the Pd nanoflakes on the MoS2 reveal nanorod-like morphology of the Pd NPs on the MoS2 support, whilst FESEM images of the Pt-Pd/MoS2 composite show Pt NPs in high density and with the average size of ~15 nm, all homogeneously electrodeposited on the Pd-MoS2 composite...
August 2, 2018: Mikrochimica Acta
Fanyu Meng, Yuanyuan Xu, Wenfei Dong, Yuguo Tang, Peng Miao
The paper describes a voltammetric method for the quantitation of the activity of telomerase extracted from cancer cells. A thiolated single-stranded telomerase substrate primer was firstly immobilized on a gold electrode. In the presence of a mixture of telomerase and deoxynucleotide triphosphates, the primer becomes elongated and contains repetitive nucleotide sequences (TTAGGG)n . After hybridization with blocker DNA, gold nanoparticles are added and captured by the elongated single-stranded DNA. This reduces the charge transfer resistance of the gold electrode...
August 1, 2018: Mikrochimica Acta
Yanbo Hou, Kuang Sheng, Yang Lu, Cui Ma, Wei Liu, Xiaoju Men, Lin Xu, Shengyan Yin, Biao Dong, Xue Bai, Hongwei Song
The authors describe a chemical sensor for dopamine (DA). It is based on the use of three-dimensional graphene oxide (3D rGO) loaded with varying amounts of AuPd bimetallic nanoparticles (3D rGO/AuPd NPs). The 3D rGO acts as an effective substrate providing a large surface area and allowing fast electron transfer. The interaction between 3D rGO and surface AuPd NPs increases the activity of the sensing material. These composites were fabricated as the active layer on an indium tin oxide for DA determination...
August 1, 2018: Mikrochimica Acta
Paramasivam Balasubramanian, Ramki Settu, Shen-Ming Chen, Tse-Wei Chen
A voltammetric sensor is described for the determination the antibiotic sulfamethoxazole (SMZ). It is based on the use of a glassy carbon electrode (GCE) modified with a nanocomposite prepared from graphitic carbon nitride and zinc oxide (g-C3 N4 /ZnO). The nanorod-like ZnO nanostructure were synthesized sonochemically. The g-C3 N4 /ZnO nanocomposite was then prepared by mixing g-C3 N4 with ZnO, followed by ultrasonication. The morphology and structure of the nanocomposite were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy and transmission electron microscopy...
July 31, 2018: Mikrochimica Acta
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