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Mikrochimica Acta

Mohammad Behbahani, Saman Bagheri, Fariborz Omidi, Mostafa Mohammadpour Amini
The authors described a new application of amino-functionalized KIT-6 for dispersive ultrasonication-assisted micro solid phase extraction of hippuric acid (HA) and methyl hippuric acid (MHA) from human urine and water samples. In the first step, an amino-functionalized mesoporous silica of type KIT-6 was synthesized. It was characterized by field emission scanning electron microscopy, Fourier transform infrared spectrometry, nitrogen adsorption-desorption analysis, thermogravimetry and X-ray diffraction. Following sorption and desorption with 1...
October 11, 2018: Mikrochimica Acta
Yi-Han Wang, Huan Xia, Ke-Jing Huang, Xu Wu, Ying-Ying Ma, Rui Deng, Yun-Fei Lu, Zi-Wei Han
A sensitive aptamer/protein binding-triggered sandwich assay for thrombin is described. It is based on electrochemical-chemical-chemical redox cycling using a glassy carbon electrode (GCE) that was modified with WSe2 and gold nanoparticles (AuNPs). The AuNPs are linked to thrombin aptamer 1 via Au-S bonds. Thrombin is first captured by aptamer 1 and then sandwiched through the simultaneous interaction with AuNPs modified with thrombin-specific aptamer 2 and signalling probe. Subsequently, the DNA-linked AuNP hybrids result in the capture of streptavidin-conjugated alkaline phosphatase onto the modified GCE through the specific affinity reaction for further signal enhancement...
October 9, 2018: Mikrochimica Acta
Azam Akbarnia, Hamid R Zare
The authors describe a DNA based voltammetric assay for the cancer biomarker microRNA-25. A glassy carbon electrode (GCE) was modified with amino-functionalized graphene quantum dots and used as an amplifier of electrochemical signals. p-Biphenol is introduced as a new electroactive probe with a fairly low working potential of 0.3 V (vs. Ag/AgCl). The stages of fabricating the electrode were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. ss-Probe DNA was immobilized on the modified GCE and then exposed to a sample containing microRNA-25...
October 9, 2018: Mikrochimica Acta
Yan Kang, Ting Wu, Xiaozhen Han, Haixin Gu, Xin Zhang
A micro surface-enhanced Raman scattering (SERS) substrate has been fabricated by electrochemical deposition of dendrite-like gold on carbon fiber needles (Au-CFNs). Scanning electron microscopy and energy dispersive spectroscopy were used to confirm the presence of the gold nanostructure on the CFNs. This substrate has a Raman scattering enhancement factor as high as 3.3 × 10^7 when using rhodamine 6G as the reporter molecule. The high SERS sensitivity is attributed to the massive hotspots on gold bulges that enhance the local surface plasmon resonance...
October 9, 2018: Mikrochimica Acta
Zehui Li, Yuheng Jiang, Zhuoya Wang, Wenbo Wang, Yi Yuan, Xiaoxue Wu, Xingchen Liu, Mingjie Li, Sobia Dilpazir, Guangjin Zhang, Dongbin Wang, Chenming Liu, Jingkun Jiang
Core-shell structured particles were prepared from carbonized zeolitic imidazolate frameworks (ZIFs) and reduced graphene oxide (rGO). The particles possess a nitrogen content of up to 10.6%. The loss of nitrogen from the ZIF is avoided by utilizing the reduction and agglomeration of graphene oxide with suitable size (>2 μm) during pyrolysis. The resulting carbonized ZIF@rGO particles were deposited on a glassy carbon electrode to give an amperometric sensor for H2 O2 , typically operated at a voltage of -0...
October 9, 2018: Mikrochimica Acta
Xiaotong Feng, Jon Ashley, Tongchang Zhou, Yi Sun
A fluorometric assay is described for doxycycline detection. It is based on the use of nitrogen-doped carbon quantum dots (NCQDs) coated with molecularly imprinted polymers (MIPs). The NCQDs were prepared by a one-step hydrothermal reaction using citric acid and ethylenediamine (EDA) as the starting materials. Afterwards, the NCQDs were incorporated into the polymer that was molecularly imprinted with doxycycline. It is found that doxycycline quenches the fluorescence of the NCQDs, and that the functional groups on the surface of NCQDs play an important role in terms of quenching efficiency...
October 6, 2018: Mikrochimica Acta
Shijia Wu, Lihong Liu, Nuo Duan, Wenyue Wang, Qianru Yu, Zhouping Wang
An aptamer-based test strip is described for visual and instrumental determination of the mycotoxin ochratoxin A (OTA). It is based on the use of NaYF4 :Yb,Er upconversion nanoparticles (UCNPs) as a label for the aptamer and on the competition between OTA and its complementary sequence for an OTA-specific aptamer. To improve the analytical performance, the optical properties of the UCNPs, the fluidity of the UCNP-aptamer conjugate, and the migration rate on the nitrocellulose membranes were investigated. Under the optimal experimental conditions and by using a 980-nm laser, the relative fluorescence intensity (test line value/control line value) is proportional to the logarithm of the OTA concentration over a range from 5 to 100 ng·mL-1 (R2  = 0...
October 5, 2018: Mikrochimica Acta
Xiao Liu, Chenghua Wei, Jing Luo, Yiping Wu, Xiaoyu Guo, Ye Ying, Ying Wen, Haifeng Yang
A photoelectrochemical (PEC) method is described for the determination of the activity of M.SssI methyltransferase (MTase). The assay relies on enzyme-linkage reactions and a DNA intercalator Ru(bpy)2 (dppz)2+ (where bpy is 2,2'-bipyridine, and dppz is dipyrido[3,2-a:2',3'-c]phenazine) which both serves as a PEC signal. The PEC electrode was obtained by immobilizing 5'-amino modified DNA strands (containing the methylation recognition site 5'-CCGG-3') on a polyethylenimine (PEI) coated ITO/SnO2 electrode with glutaraldehyde as crosslinking agent...
October 5, 2018: Mikrochimica Acta
Fangmei Zhang, Pinyi Ma, Xinyu Deng, Ying Sun, Xinghua Wang, Daqian Song
Glutathione-capped water-soluble CuInS/ZnS quantum dots (QDs) were prepared by a microwave-assisted method. Their fluorescence, with excitation/emission peaks at 380/570 nm, is found to be quenched by hydrogen peroxide (H2 O2 ) that is produced by the uricase catalyzed oxidation of uric acid (UA) and oxygen. The findings are used in a quenchometric method for the determination of UA. The effects of different ligands on the QDs, of pH value, buffers, enzyme ratio and reaction time were optimized. The detection limit for UA is 50 nM which is lower than other QD-based method, and the detection ranges extends from 0...
October 5, 2018: Mikrochimica Acta
Yanying Wang, Li Yang, Yaqin Liu, Qingbiao Zhao, Fang Ding, Ping Zou, Hanbing Rao, Xianxiang Wang
A composite consisting of NiCo2 S4 and reduced graphene oxide (rGO) was prepared via a hydrothermal process. Compared to individual NiCo2 S4 nanomaterials or reduced graphene oxide, the composite exhibits enhanced oxidase-like activity. It is found that dopamine (DA) inhibits the ability of NiCo2 S4 -rGO to oxidize the substrate 3,3',5',5'-tetramethylbenzidine (TMB) to form blue colored ox-TMB. Based on these findings, a colorimetric method for determination of DA was worked out. The absorption, best measured at 652 nm, increases linearly in the 0...
October 4, 2018: Mikrochimica Acta
Masoumeh Mohammadnejad, Zahra Gudarzi, Shokoofeh Geranmayeh, Vahideh Mahdavi
The authors describe a method for the extraction of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) from agricultural products. The metal organic framework (MOF) HKUST-1 (a copper(II) benzene-1,3,5-tricarboxylate) was used as a sorbent for efficient clean-up and preconcentration of MCPA. The effects of pH value, stirring time, amount of sorbent on extraction were optimized by central composite design. Ultrasonic waves were used for desorption procedure and its advantage was demonstrated for an increase in extraction recovery...
October 4, 2018: Mikrochimica Acta
Wei Wei, Min Wei, Lihong Yin, Yuepu Pu, Songqin Liu
The authors describe a fluorometric method for improving the determination of the cancer biomarker 8-hydroxy-2'-deoxyguanosine (8-OHdG). A nicking endonuclease (NEase)-powered 3-D DNA nanomachine was constructed by assembling hundreds of carboxyfluorescein-labeled single strand oligonucleotides (acting as signal reporter) and tens of swing arms (acting as single-foot DNA walkers) on a gold nanoparticle (AuNP). The activity of this DNA nanomachine was controlled by introducing the protecting oligonucleotides...
October 3, 2018: Mikrochimica Acta
Shengjun Bu, Kuiyu Wang, Chuanjing Ju, Ye Han, Zhongyi Li, Peng Du, Zhuo Hao, Changtian Li, Wensen Liu, Jiayu Wan
The published version of this article, unfortunately, contained error. The authors are re-writing to express their sincere apology for a mistake that a mark "10-5 , 10-4 , 10-3 , 10-2 , 10-1 CFU•mL-1 " in the legend of Fig. 2 was not corrected as "105 , 104 , 103 , 102 , 101 CFU•mL-1 ".
October 3, 2018: Mikrochimica Acta
Dan Song, Rong Yang, Shunyan Fang, Yanping Liu, Feng Long, Anna Zhu
A SERS-based aptasensor for ochratoxin A (OTA) is described. It is making use of Fe3 O4 @Au magnetic nanoparticles (MGNPs) and of Au@Ag nanoprobes modified with the Raman reporter 5,5-dithiobis-(2-nitrobenzoic acid; DTNB). Au-DTNB@Ag NPs were modified with the OTA aptamer (aptamer-GSNPs) and used as Raman signal probes. The SERS peak of DTNB at 1331 cm-1 was used for quantitative analysis. MGNPs modified with cDNA (cDNA-MGNPs) were used as capture probes and reinforced substrates. When the Au-DTNB@Ag-Fe3 O4 @Au complexes are formed through oligonucleotide hybridization, the Raman signal intensity of the Raman probe is significantly enhanced...
October 3, 2018: Mikrochimica Acta
Mohammad Mahdi Bordbar, Bahram Hemmateenejad, Javad Tashkhourian, S F Nami-Ana
A colorimetric array, which can discriminate 20 food antioxidants of natural, synthetic and biological groups, is described. It consists of gold and silver nanoparticles that were synthesized using six different reducing and/or capping agents. The function of the array relies on the interaction of the antioxidants with the nanoparticles which causes aggregation or morphological changes. This, in turn, causes a change in the sensors' colors. The array produces a unique combination of colors for each antioxidant...
October 3, 2018: Mikrochimica Acta
Shengnan Xu, Ligang Chen, Ling Ma
The authors describe a fluorescent probe for sensitive and selective determination of quercetin, an indicator for the freshness of drinks. The probe consists of silica ball encapsulated graphitic carbon nitride (g-C3 N4 ) modified with a molecularly imprinted polymer (MIP). It was synthesized via reverse microemulsion. The resulting MIP@g-C3 N4 nanocomposite was characterized by fluorescence spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction...
October 3, 2018: Mikrochimica Acta
Lude Wang, Yang Chen
A colorimetric and fluorescent pH probe was designed by doping carbon dots (C-dots) with Eu(III), Tb(III) and 2,6-pyridinedicarboxylic acid (DPA). The resulting nanoparticles were applied as fluorescent indicators for pH values (best detected at excitation/emission wavelengths of 272/545, 614 nm). The pH induced optical effects are due to pH induced variations in energy transfer. The fluorescence of the probe shows a continuous color variation, and a linear change with pH values in the range from 3.0 to 10...
October 2, 2018: Mikrochimica Acta
Caiyun Kong, Linna Gao, Zhengbo Chen
An aptamer based assay is described for the colorimetric detection of adenosine. The presence of adenosine triggers the deformation of hairpin DNA oligonucleotide (HP1) containing adenosine aptamer and then hybridizes another unlabeled hairpin DNA oligonucleotide (HP2). This leads to the formation of a double strand with a blunt 3' terminal. After exonuclease III (Exo III)-assisted degradation, the guanine-rich strand (GRS) is released from HP2. Hence, the adenosine-HP1 complex is released to the solution where it can hybridize another HP2 and initiate many cycles of the digestion reaction with the assistance of Exo III...
October 2, 2018: Mikrochimica Acta
Hongyu Chen, Kaili He, Huan Li, Youyu Zhang, Shouzhuo Yao
The authors describe an upconversion nanoparticle-based (UCNP-based) fluorometric method for ultrasensitive and selective detection of Cu2+ . The UCNPs show a strong emission band at 550 nm under near-infrared excitation at 980 nm. The principle of the strategy is that gold nanoparticles (AuNP) can quench the fluorescence of UCNP. In contrast, the addition of L-cysteine (Cys) can induce the aggregation of AuNP, resulting in a fluorescence recovery of the UCNPs. On addition of Cu2+ , it oxidizes Cys to cystine and is reduced to Cu+ ...
October 1, 2018: Mikrochimica Acta
Liang Ma, Ting Guo, Shuli Pan, Yuhao Zhang
A fluorometric patulin (PAT) assay is presented that is based on the use of magnetic reduced graphene oxide (rGO) and DNase I. The fluorescence of the PAT aptamer labelled with 6-carboxyfluorescein (FAM) is quenched by magnetized reduced graphene oxide (rGO-Fe3 O4 ) due to fluorescence resonance energy transfer (FRET). However, in the presence of PAT, the labelled aptamer is stripped off from rGO-Fe3 O4 . The rGO-Fe3 O4 is then magnetically separated so that the fluorescence of free labelled PAT aptamer is restored...
October 1, 2018: Mikrochimica Acta
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