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Mikrochimica Acta

Priyal Chikhaliwala, Rakesh Rai, Sudeshna Chandra
The authors describe an electrochemical immunoassay for simultaneous determination of alpha-fetoprotein (AFP) and glypican-3 (GPC-3) which are important biomarkers for early detection of hepatocellular carcinoma (HCC). Magnetite (Fe3 O4 ) nanoparticles (NPs) were decorated with hyperbranched amino functionalized dendrimers. The modified NPs were coupled to the antibodies against AFP and GPC-3. The electrochemical behaviour of the Fe3 O4 NPs and dendrimer-modified NPs were studied. A glassy carbon electrode was then modified with the NP-conjugated antibodies and biomolecular interactions were studied by using cyclic voltammetry and electrochemical impedance spectroscopy...
March 23, 2019: Mikrochimica Acta
Yao Tong, Xueyan Liu, Lei Zhang
Magnetic porous microspheres composed of Fe3 C, MnO and graphitic carbon (Fe3 C/MnO/GC) were prepared by a one-pot method. A polycondensate obtained from urea and formaldehyde served as the carbon source and was calcined in the presence of metallic iron and manganese to yield Fe3 C/MnO/GC. The resultant hybrid has highly mesoporous architecture, large specific surface, graphitic structure and adequate saturation magnetism. It is shown to possess excellent pre-concentration ability for herbicides (monuron, chlortoluron, atrazine and terbutylhylazine)...
March 23, 2019: Mikrochimica Acta
Zhu Feng, Shaotao Zhi, Lei Guo, Yong Zhou, Chong Lei
The authors describe an integrated microfluidic chip for immunodetection of the prostate specific antigen (PSA) by using giant magnetoimpedance (GMI) sensor. This chip contains an immunoreaction platform and a biomarker detection system. The immunoreaction platform contains an incubation chamber and a reactive chamber to implement immunological reaction in microfluidics. The system can detect PSA rapidly with ultra-high sensitivity. Both are fabricated by MEMS technology. Immunomagnetic beads (If PSA binds to its antibody (that is labeled with immunomagnetic beads; IMBs) it will be trapped on the surface of self-assembled film...
March 22, 2019: Mikrochimica Acta
Dnyandeo Pawar, Sangeeta N Kale
The mesmerizing properties of nanomaterials and the features offered by optical fibers can be combined to result in an attractive new platform for chemical sensing. This review (with 230 refs.) summarizes the progress made in the past five years in the field of fiber-optic sensors: The first group comprises metals and metal oxides and their composites, and the second group comprises graphene, graphene oxides and CNTs, and its composites. By combining these nanocomposites with various optical fiber geometries, numerous sensors have been realized...
March 22, 2019: Mikrochimica Acta
Mohammad Saremi, Amir Amini, Hamid Heydari
An ultrasensitive electrochemiluminescence (ECL) disposable aptamer sensor (aptasensor) is presented for detection of myocardial infarction biomarker by quantification of troponin I in blood serum. A screen-printed electrode was modified with (a) aptamer-modified gold nanoparticles, (b) cyclometallated iridium(III)-poly-4-vinylpyridine nanoparticles, and (c) nitrogen-doped graphene in order to increase the loading capacity and conductivity of the aptasensor. If the aptasensor is exposed to troponin I, it will bind to the aptamer and desorb the aptamer from gold nanoparticles and the surface of the electrode...
March 22, 2019: Mikrochimica Acta
Chunyang Zhou, Zhi Yu, Weili Yu, Huiwen Liu, Hao Zhang, Chunlei Guo
An ultrasensitive and highly selective method is described for the determination of adenosine triphosphate (ATP) via surface-enhanced Raman scattering (SERS). Two split aptamers are used for specific recognition of ATP. They were attached to two SERS substrates. The first was placed on a nanolayer of gold nanoparticle-decorated graphene oxide (GO/Au3), and the other on gold nanoparticles (Au2). When ATP is introduced, it will interact with the split aptamers on the gold nanostructures to form a sandwich structure that brings the GO/Au3 nanolayer and the Au2 nanoparticle in close proximity...
March 20, 2019: Mikrochimica Acta
Shiqing Luo, Yanming Miao, Junping Guo, Xiaojie Sun, Guiqin Yan
Mesoporous molecularly imprinted polymers (MIPs) containing mangnanese-doped ZnS quantum dots (Mn-ZnS QDs) were prepared for specific recognition and detection of 4-nitrophenol (4-NP). The Mn-ZnS QDs display orange room-temperature phosphorescence with excitation/emission peaks at 295/590 nm and a decay time of 2.0 ms. In the presence of 4-NP, the orange phosphorescence is strongly reduced. Phosphorescence drops linearly in the 0.1-100 μM 4-NP concentration range, and the detection limit is 60 nM. The detection limit is far lower than the maximally allowed 4-NP concentrations in surface water and drinking water as specified by the U...
March 19, 2019: Mikrochimica Acta
Ran Liu, Li Zuo, Xiaorong Huang, Shimeng Liu, Guiying Yang, Shiya Li, Changyin Lv
It is shown that metallothionein-stabilized copper nanoclusters (MT-CuNCs) display catalase-like activity. In the presence of either lead(II) or mercury(II), the catalase-like activity is converted to a peroxidase-like activity. On addition of Pb(II) or Hg(II), the inhibitory effect of MT-CuNCs on the chromogenic reaction of 3,3',5,5'-tetramethylbenzidine (TMB) with H2 O2 is weakened. On the other hand, the catalytic effect of the nanoclusters on the chromogenic reaction is increased. The system MT-CuNCs-Pb(II)/Hg(II) exhibits high affinity for the substrates TMB and H2 O2 ...
March 19, 2019: Mikrochimica Acta
Taiping Qing, Caicheng Long, Xuan Wang, Kaiwu Zhang, Peng Zhang, Bo Feng
Micrococcal nuclease (MNase) is a naturally-secreted nucleic acid degrading enzyme with important role in the spread of the bacteria in an infected host. The content of MNase can be used to estimate the pathogenicity of Staphylococcus aureus (S. aureus). A fluorometric method is described here for determination of the activity of MNase and for identification of S. aureus using DNA templated fluorescent copper nanoclusters (CuNC). A double-stranded DNA (dsDNA) with AT-rich regions and protruding 3'-termini was identified as a high-selectivity substrate for MNase and as a template for CuNC...
March 18, 2019: Mikrochimica Acta
Yanying Wang, Yan Yang, Wei Liu, Fang Ding, Ping Zou, Xianxiang Wang, Qingbiao Zhao, Hanbing Rao
A dual-mode method was developed for the determination of ascorbic acid (AA) and of ascorbic acid oxidase (AA-Ox) activity. It combines the advantages of ratiometric fluorometry and colorimetry. The assay is based on the oxidation of o-phenylenediamine (OPDA) by permanganate (KMnO4 ). A yellow substance (referred to as oxOPDA) with an absorption peak at 425 nm is rapidly produced in the presence of the oxidant. oxOPDA reduces the blue fluorescence of carbon dots (C-dots) peaking at 450 nm (upon 380-nm excitation), and a new emission peak is found at 565 nm...
March 16, 2019: Mikrochimica Acta
Hanh Hong Mai, Dinh Hoang Tran, Ewald Janssens
A sensitive non-enzymatic fluorescent glucose sensor, consisting of vertically aligned ZnO nanotubes (NTs) grown on low-cost printed circuit board substrates, is described. The ZnO NTs were synthesized by a one-step hydrothermal method without using a seed layer. The sensor function is based on the photoluminescence (PL) quenching of ZnO NTs treated with different concentrations of glucose. The UV emission (emission maximum at 384 nm under 325 nm excitation) decreases linearly with increasing glucose concentration...
March 16, 2019: Mikrochimica Acta
Xinnan Liu, Wentao Zhang, Chengyuan Yang, Yuan Yao, Lunjie Huang, Sihang Li, Jianlong Wang, Yanwei Ji
The authors describe a fluorometric method for the quantification of tannic acid (TA). MoO3-x quantum dots (QDs) can selectively capture TA via the formation of an organic molybdate complex. This causes an electron transfer effect and an inner filter effect to result in synergistic quenching of the fluorescence of the QDs. TA can be detected via this effect with a linear response in the of 0.1-10 μM concentration range and a lower detection limit of 30 nM within 1 min. The use of such QDs as a quenchable fluorescent probe warrants good selectivity even in the presence of relatively high concentration of potentially interferents and makes the method suitable for real sample analysis...
March 16, 2019: Mikrochimica Acta
Xuan Yang, Xiaodong Sun, Zijie Feng, Yingxiang Du, Jiaquan Chen, Xiaofei Ma, Xiaoqi Li
Magnetic nanoparticles (MNPs) modified with β-cyclodextrin and mono-6-deoxy-6-(1-methylimidazolium)-β-cyclodextrin tosylate (an ionic liquid), which called MNP-β-CD and MNP-β-CD-IL, were coated into the capillary inner wall. Compared to an uncoated capillary, the new systems show good reproducibility and durability. The systems based on the use of MNP-β-CD or MNP-β-CD-IL as stationary phases were established for enantioseparation of Dns-modified amino acids. Improved resolutions were obtained for both CEC systems...
March 15, 2019: Mikrochimica Acta
Weidan Chang, Weipeng Liu, Ying Liu, Fangfang Zhan, Huifang Chen, Hongtao Lei, Yingju Liu
A colorimetric method is presented for the detection of specific nucleotide sequences in plant pathogens. It is based on the use of CRISPR/Cas9-triggered isothermal amplification and gold nanoparticles (AuNPs) as optical probes. The target DNA was recognized and broken up by a given Cas9/sgRNA complex. After isothermal amplification, the product was hybridized with oligonucleotide-functionalized AuNPs. This resulted in the aggregation of AuNPs and a color change from wine red to purple. The visual detection limit is 2 pM of DNA, while a linear relationship exists between the ratio of absorbance at 650 and 525 nm and the DNA concentration in the range from 0...
March 15, 2019: Mikrochimica Acta
Chu Hongxia, Li Zaijun, Li Ruiyi, Wang Guangli, Gu Zhiguo
Graphene quantum dots (GQDs) were prepared via pyrolysis of citric acid and glutamic acid, then reacted with chlorauric acid to form a gold/graphene quantum dot hybrid (Au/GQD), and finally connected with hairpin DNA probe 1 (H1) and thionine (Thi). The H1-Au/GQD-Thi composite is found to be a viable redox probe for electrochemical and aptamer-based determination of vascular endothelial growth factor VEGF165. A dual amplification strategy is employed based on the use of molecular machine and the Au/GQD. Each single VEGF165 molecule can bind two DNA probes via specific aptamer-target recognition to produce a molecular machine...
March 15, 2019: Mikrochimica Acta
Kobra Zavar Mousavi, Yadollah Yamini, Babak Karimi, Shahram Seidi, Mojtaba Khorasani, Mostafa Ghaemmaghami, Hojatollah Vali
The authors describe the preparation of two kinds of periodic mesoporous organosilicas (PMOs). The first kind is monofunctional and has a bridged alkyl imidazolium framework (PMO-IL). The other is a two-dimensional (2D) hexagonal bifunctional periodic mesoporous organosilica (BFPMO) with bridged IL-phenyl or -ethyl units. The CPMOs were utilized as highly sensitive and stable sorbents for microextraction by packed sorbent. The materials were characterized by SEM, TEM, FT-IR, and N2 adsorption-desorption analysis...
March 13, 2019: Mikrochimica Acta
Bao-Zhu Chi, Chen-Lu Wang, Zhi-Qiao Wang, Ting Pi, Xiao-Li Zhong, Chao-Qun Deng, Yu-Chuan Feng, Zhi-Mei Li
The activity of terminal deoxynucleotidyl transferase (TdTase) is a biomarker for routine diagnosis of acute leukemia. A method has been developed for the determination of TdTase activity. It is based on the use of silver nanoclusters (AgNCs) whose yellow fluorescence is enhanced by an in-situ grown DNA tail of TdTase-polymerized and guanine-rich DNA at the 3' end of a hairpin DNA. The fluorescence, best measured at excitation/emission peaks of 530/585 nm, increases linearly in the 1 to 35 mU mL-1 TdTase activity range...
March 13, 2019: Mikrochimica Acta
Jinqiong Xu, Xiujuan Qiao, Yuan Wang, Qinglin Sheng, Tianli Yue, Jianbin Zheng, Ming Zhou
An aptamer based impedimetric assay for the mycotoxin patulin (PAT) is described. A glassy carbon electrode (GCE) was modified with black phosphorus nanosheets (BP NSs) and modified with PAT aptamer by electrostatic attraction. Detection is based on the variations of electron transfer resistance at the modified electrode surface. This assay can detect PAT over a linear range that extends from 1.0 nM to 1.0 μM with a 0.3 nM detection limit. To improve the performance of the sensor, the BP NS-GCE was further modified with gold nanoparticles and then with thiolated PAT aptamer...
March 13, 2019: Mikrochimica Acta
Jiawen Wang, Zidan Wang, Nianrong Sun, Chunhui Deng
The authors are presenting a novel strategy for global phosphoproteome recognition in practical samples. It integrates metal oxide affinity chromatography (MOAC) and immobilization metal ion affinity chromatography (IMAC). This resulted in a kind of titanium dioxide/ion-based multifunctional probe (dubbed T2M). The T2M combines the features of MOAC and IMAC including their recognition preferences towards mono- and multi-phosphorylated peptides. Hence, they exhibit an outstanding recognition capability towards global phosphoproteome, high sensitivity (the limit of detection of which is merely 10 fmol) and excellent specificity in MALDI-TOF MS detection...
March 13, 2019: Mikrochimica Acta
Tingting Zhang, Haixin Xu, Zhiqian Xu, Yue Gu, Xiaoyi Yan, He Liu, Nannan Lu, Siyuan Zhang, Zhiquan Zhang, Ming Yang
An antifouling electrochemical aptasensor for ATP is described that has a zwitterionic self-assembled sensing interface on a glassy carbon electrode modified with a reduced graphene oxide carbon nanofiber (GO-CNF). The GO-CNF was first modified by self-polymerization of dopamine which provided a platform for simultaneously self-assembly of the ATP aptamer and cysteine. By using hexacyanoferrate as the electrochemical probe, in the presence of ATP, the aptamer strands fold around ATP molecules, thus leading to the variation of the electrochemical signal...
March 13, 2019: Mikrochimica Acta
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