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Mikrochimica Acta

Shuo Liu, Aaron R Hawkins, Holger Schmidt
This review (with 90 refs.) covers the state of the art in optofluidic devices with integrated solid-state nanopores for use in detection and sensing. Following an introduction into principles of optofluidics and solid-state nanopore technology, we discuss features of solid-state nanopore based assays using optofluidics. This includes the incorporation of solid-state nanopores into optofluidic platforms based on liquid-core anti-resonant reflecting optical waveguides (ARROWs), methods for their fabrication, aspects of single particle detection and particle manipulation...
April 2016: Mikrochimica Acta
Yun Ding, Aaron M Fleming, Cynthia J Burrows
The α-hemolysin (α-HL) nanopore analyzes DNA as it is electrophoretically driven through the pore. The respective current vs. time (i-t) traces depends on the DNA sequence, its secondary structures, or on the physical conditions of the analysis. The current study describes analysis of a DNA hairpin with a 5'-extension with the α-HL nanopore in the presence of the polyamines spermine (Spm), spermidine (Spd), and putrescine (Put). These studies identified a new i-t trace characteristic of the DNA-polyamine complex...
March 2016: Mikrochimica Acta
Gema M Durán, Tomás E Benavidez, Ángel Ríos, Carlos D García
A simple and inexpensive method to fabricate a colloidal CdSe/ZnS quantum dots-modified paper-based assay for glucose is herein reported. The circular paper sheets were uniformly loaded and displayed strong fluorescence under a conventional hand-held UV lamp (365 nm). The assay is based on the use of glucose oxidase enzyme (GOx), which impregnated the paper sheets, producing H2O2 upon the reaction with the glucose contained in the samples. After 20 min of exposure, the fluorescence intensity changed due to the quenching caused by H2O2...
February 1, 2016: Mikrochimica Acta
Xuehua Li, Zhiwei Zhao, Chen Pan
An electrochemical approach is introduced for synthesis of carbon dots (CDs) by exfoliating graphite rods at a voltage of 15 V in an electrolyte consisting of a mixture of water and two ionic liquids. It is found that the size of the CDs can be tuned by varying the fraction of water in the mixed electrolyte; CDs in sizes of 4.9, 4.1 and 3.1 nm are obtained if the electrolyte contains water in fractions of 24, 38 and 56 %, respectively. The CDs have a quantum yield of almost 10 % and display the typical excitation wavelength-dependent maxima of photoluminescence, strongest at excitation/emission wavelengths of 360/440 nm...
2016: Mikrochimica Acta
Eda Mehmeti, Dalibor M Stanković, Sudkate Chaiyo, Ľubomir Švorc, Kurt Kalcher
A carbon paste electrode bulk was modified with MnO2 and investigated for use as an electrochemical sensor for riboflavin (vitamin B2) using differential pulse voltammetry (DPV). Riboflavin displays a well expressed oxidation peak at -0.15 V (versus Ag/AgCl) in solutions with a pH value of 2. Effects of pH value, pulse amplitude and pulse time were optimized by employing DPV. The signals obtained are linearly related to the concentrations of riboflavin in the range from 0.02 to 9 μM. Other features include a 15 nM detection limit, and good reproducibility (±3 %) and repeatability (±2 %)...
2016: Mikrochimica Acta
Nannan Liu, Zekun Yang, Xiaowen Ou, Benmei Wei, Juntao Zhang, Yongmei Jia, Fan Xia
Biological nanochannels or nanopores play a crucial role in basic biochemical processes in cells. Artificial nanopores possessing dimensions comparable to the size of biological molecules and mimicking the function of biological ion channels are of particular interest with respect to the design of biosensors with a sensitivity that can go down to the fM level and even to single molecule detection. Nanopore-based analysis (NPA) is currently a new research field with fascinating prospects. This review (with 118 refs...
2016: Mikrochimica Acta
Beata Zawisza, Anna Baranik, Ewa Malicka, Ewa Talik, Rafał Sitko
We describe a novel solid phase sorbent that was synthesized by coupling graphene oxide (GO) to ethylenediamine (EDA). This nanomaterial (referred to as GO-EDA) is capable of adsorbing the ions of iron, cobalt, nickel, copper, zinc and lead. The ethylenediamine-modified graphene oxide was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. The analytical procedure relies on (a) sorption of metal ions on GO-EDA dispersed in aqueous samples; (b) filtering, and (c) direct submission of the filter paper to energy-dispersive X-ray fluorescence spectrometry...
2016: Mikrochimica Acta
Ewa Biaduń, Monika Sadowska, Natalia Ospina-Alvarez, Beata Krasnodębska-Ostręga
Alumina (Al2O3) with an average particle size of 63 μm was modified with the anionic surfactant sodium dodecyl sulfate (SDS) and then applied to (i) solid phase extraction and separation of both thallium(I) and thallium(III), and (ii) preconcentration of Tl(III) from waste water samples. Only Tl(III), in the form of its complex with diethylenetriaminepentaacetate (DTPA), was retained on the sorbent, from where it can be eluted with 40 % nitric acid. Thallium species were then quantified by ICP MS. The method was characterized by a LOD of 25 pg of Tl(I) and 160 pg of Tl(III) in 10 mL samples...
2016: Mikrochimica Acta
Maedeh Roushan, Zubair Azad, Shuang Fang Lim, Hong Wang, Robert Riehn
Intercalating fluorescent probes are widely used to visualize DNA in studies on DNA-protein interactions. Some require the presence of adenosine triphosphate (ATP). We have investigated the mechanical properties of DNA stained with the fluorescent intercalating dyes YOYO-1 and YOYO-3 as a function of ATP concentrations (up to 2 mM) by stretching single molecules in nanofluidic channels with a channel cross-section as small as roughly 100×100 nm(2). The presence of ATP reduces the length of the DNA by up to 11 %...
June 1, 2015: Mikrochimica Acta
Winfried Nischkauer, Marie-Alexandra Neouze, Frank Vanhaecke, Andreas Limbeck
We report on the use of mesoporous silica microparticles (μPs) functionalized with quarternary amino groups for the isolation of platinum and palladium tetrachloro complexes from aqueous road dust digests. The μPs have a size ranging from 450 to 850 nm and are suspended directly in the aqueous digests, upon which the anionic Pt and Pd complexes are retained on the cationic surface. Subsequently, the μPs are separated by centrifugation. Elements that cause spectral interferences in ICP-MS determination of Pt and Pd can be quantitatively removed by adding fresh 0...
2015: Mikrochimica Acta
Melissa R Dewi, Geoffry Laufersky, Thomas Nann
Hetero-dimeric magnetic nanoparticles of the type Au-Fe3O4 have been synthesised from separately prepared, differently shaped (spheres and cubes), monodisperse nanoparticles. This synthesis was achieved by the following steps: (a) Mono-functionalising each type of nanoparticles with aldehyde functional groups through a solid support approach, where nanoparticle decorated silica nanoparticles were fabricated as an intermediate step; (b) Derivatising the functional faces with complementary functionalities (e...
2015: Mikrochimica Acta
Jinqi Wang, Na Yao, Mei Li, Jia Hu, Jianwei Chen, Qiaoling Hao, Kangbing Wu, Yikai Zhou
Micro-nano structured Cu-Co was in situ fabricated on the surface of a gold electrode via electrochemical reduction of CuCl2 and Co(NO3)2. It is shown that the shape of the particles can be controlled by variation of deposition current, deposition time, pH value and the ratio of Cu(II) and Co(II) ions. If prepared under current of -200 μA in 0.1 M, pH 4.0 acetate buffer solution, the film possesses high catalytic activity towards the electrochemical oxidation of glucose at a largely increased oxidation current compared to a non-modified surface...
2015: Mikrochimica Acta
Aleksandra Jaworska, Tomasz Wojcik, Kamilla Malek, Urszula Kwolek, Mariusz Kepczynski, Abu A Ansary, Stefan Chlopicki, Malgorzata Baranska
Fluorescence and surface-enhanced Raman scattering (SERS) spectroscopy were employed to investigate the cellular uptake of rhodamine 6G (R6G) alone and of R6G loaded with gold nanoparticles (AuNPs) by endothelial cells. R6G plays the role of a Raman reporter in SERS but also displays strong fluorescence. The presence of bare R6G molecules and R6G-AuNPs in the cytoplasm of the cells is detected via the 2D fluorescence of the dye after a 0.5 h of the incubation with R6G and R6G-AuNPs, and then the concentration of the dye increases within 4 h of exposure...
2015: Mikrochimica Acta
Bankim J Sanghavi, Otto S Wolfbeis, Thomas Hirsch, Nathan S Swami
Nanomaterial-modified detection systems represent a chief driver towards the adoption of electrochemical methods, since nanomaterials enable functional tunability, ability to self-assemble, and novel electrical, optical and catalytic properties that emerge at this scale. This results in tremendous gains in terms of sensitivity, selectivity and versatility. We review the electrochemical methods and mechanisms that may be applied to the detection of neurological drugs. We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system...
2015: Mikrochimica Acta
Ajeet Kaushik, Rajesh Kumar, Eric Huey, Shekhar Bhansali, Narayana Nair, Madhavan Nanir
This review (with 129 refs.) gives an overview on how the integration of silica nanowires (NWs) into micro-scale devices has resulted, in recent years, in simple yet robust nano-instrumentation with improved performance in targeted application areas such as sensing. This has been achieved by the use of appropriate techniques such as di-electrophoresis and direct vapor-liquid-growth phenomena, to restrict the growth of NWs to site-specific locations. This also has eliminated the need for post-growth processing and enables nanostructures to be placed on pre-patterned substrates...
November 1, 2014: Mikrochimica Acta
Jingjing Wu, Yingyue Zhu, Feng Xue, Zhanlong Mei, Li Yao, Xin Wang, Lei Zheng, Jian Liu, Guodong Liu, Chifang Peng, Wei Chen
The method referred to as "systemic evolution of ligands by exponential enrichment" (SELEX) was introduced in 1990 and ever since has become an important tool for the identification and screening of aptamers. Such nucleic acids can recognize and bind to their corresponding targets (analytes) with high selectivity and affinity, and aptamers therefore have become attractive alternatives to traditional antibodies not the least because they are much more stable. Meanwhile, they have found numerous applications in different fields including food quality and safety monitoring...
April 2014: Mikrochimica Acta
Sebastian Kersting, Valentina Rausch, Frank F Bier, Markus von Nickisch-Rosenegk
We report on the development of an on-chip RPA (recombinase polymerase amplification) with simultaneous multiplex isothermal amplification and detection on a solid surface. The isothermal RPA was applied to amplify specific target sequences from the pathogens Neisseria gonorrhoeae, Salmonella enterica and methicillin-resistant Staphylococcus aureus (MRSA) using genomic DNA. Additionally, a positive plasmid control was established as an internal control. The four targets were amplified simultaneously in a quadruplex reaction...
2014: Mikrochimica Acta
Lena Danckert, Sebastian Hoppe, Frank F Bier, Markus von Nickisch-Rosenegk
We report on an approach to rapidly screen thousands of Salmonella Enteritidis proteins with the goal of identifying novel immunodominant proteins. We used a microarray-based system that warrants high throughput and easy handling. Seven immunogenic candidates were selected after screening. Comparative analyses by ELISA and microarrays manifested their immunodominant character. The large repetitive protein (SEN4030) that plays a role as a putative adhesin in initial cell surface interaction and is highly specific to Salmonella is considered to be the most suitable protein for a diagnostic approach...
2014: Mikrochimica Acta
Jan M Ruijter, Peter Lorenz, Jari M Tuomi, Michael Hecker, Maurice J B van den Hoff
The analysis of quantitative PCR data usually does not take into account the fact that the increase in fluorescence depends on the monitoring chemistry, the input of ds-DNA or ss-cDNA, and the directionality of the targeting of probes or primers. The monitoring chemistries currently available can be categorized into six groups: (A) DNA-binding dyes; (B) hybridization probes; (C) hydrolysis probes; (D) LUX primers; (E) hairpin primers; and (F) the QZyme system. We have determined the kinetics of the increase in fluorescence for each of these groups with respect to the input of both ds-DNA and ss-cDNA...
2014: Mikrochimica Acta
Elżbieta Zambrzycka, Beata Godlewska-Żyłkiewicz
A new ruthenium ion imprinted polymer was prepared from the Ru(III) 2-thiobarbituric acid complex (the template), methacrylic acid or acrylamide (the functional monomers), and ethylene glycol dimethacrylate (the cross-linking agent) using 2,2'-azobisisobutyronitrile as the radical initiator. The ion imprinted polymer was characterized and used as a selective sorbent for the solid phase extraction of Ru(III) ions. The effects of type of functional monomer, sample volume, solution pH and flow rate on the extraction efficiency were studied in the dynamic mode...
2014: Mikrochimica Acta
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