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Gold nanoparticles (AuNPs) decorated with thiol-modified DNA (HS-DNA) strands are an extensively studied, easily adjustable, and highly controllable material for constructing 3D nanostructures with various shapes and functions. However, few reproducible and robust methods involving DNA templates as a key reagent are available for obtaining 3D nanoparticle assemblies. It is still challenging to strictly control the number and location of DNA strands on the AuNP surface. Here, we introduce an efficient approach for the surface modification of AuNPs using unmodified DNA oligonucleotides by building DNA cages that trap the nanoparticles. This enables us to vary the process of nanostructure assembly and create anisotropic nanoparticles that are necessary for directed structure construction. This developed method simplifies the production process in comparison with conventional HS-DNA modification protocols and helps to precisely control the density and position of functional DNA strands designed for further hybridization with other AuNP conjugates.

Functionalization of gold nanoparticles (AuNPs) is one of the important techniques used in production of nanomaterials and it is necessary for successful application of AuNPs arrays in catalysis, drug delivery, sensors, plasmonics and electronics. AuNPs functionalized with thiol-modified DNA strands (HS-DNA) are a well known, easily controllable, and highly adjustable product for assembling 3D nanostructures with various shapes and functions. DNA templates are widely used for controlling and measuring the distance between objects at molecular level due to its exclusive chemical structure and physical properties. However, few reproducible and robust methods involving DNA template as a key reagent are available for obtaining anisotropic nanoparticle assemblies. It is important to strictly control the number and location of DNA strands on the AuNPs surface. In this thesis, we introduce an efficient approach for surface functionalization of AuNPs using unmodified DNA oligonucleotides by building DNA cages that trap nanoparticles. Edges of a DNA cage are used for positioning functional oligonucleotides for further application of obtained asymmetrically finctionalized AuNPs in various DNA circuits for nucleic acid detection and nanostructure assembly. This enabled us to vary the process of nanoassembly, and create anisotropic nanoparticles that are necessary for directed structure construction without involving DNA origami approach. The developed method simplifies production process in comparison with conventional HS-DNA modification protocols and helps to precisely control the density and position of functional DNA strands designed for further hybridization with other AuNP conjugates. In this work we developed a protocol for direct module assembly of nanostructures that can be applied for nucleic acid detection. The method was validated to be robust in DNA circuits and nucleic acid delivery into cell culture.

Electrochemical DNA biosensors show great potential for the sensitive and sequence-specific detection of disease pathogens. To date, although there are a large number of published articles showing various sensing strategies of an electrochemical biosensor, only a few of those studies actually reach the commercialization phase, because addressing one technical issue would usually be at the expense of another. Moreover, there are various adoptable formats in electrochemical biosensors. Current approaches may or may not use enzymes, immobilize DNA probes, label the sensing substrates with an electroactive reporter molecule, or any combination of these. Although much has been paid to individual advantages and disadvantages, there are a very limited number Review articles studying and analyzing the synergistic aspects of various detection strategies when combined with each other. It is the aim of this Review to highlight the hotspots for innovation when these strategies are used in tandem, in order to create more streamlined improvements in making a versatile biosensor platform that can be administered at point of care.

We report a low-cost Polymer-based Micro Electrochemical Sensor (PMES) system for the detection of the Cordyceps sinensis's DNA (CorDNA). With the electrochemical impedance spectroscopy (EIS), solution with different CorDNA concentrations can be significantly discriminated. Through the equivalent circuit model (ECM), CorDNA concentrations can be quantified by the solution resistance Rsol and double layer capacitance Cdl. The limit of detection (LOD) of PMES was 10 nM. Moreover, a portable electrochemical sensor system integrating MCU for CorDNA detection was built. Compared with conventional PCR-based methods, PMES has lower consumption sample volume of 5 μL, shorter response time and lower cost. © 15CBMS-0001.

In this paper, we present a nano-spike electric protein extraction (NS-EPEx) chip for highly energy-efficient protein extraction from mammalian cells. 3D periodic Nano-spikes (NSs) arrays with controllable dimensions were fabricated on low-cost Aluminum (Al) foils using scalable nano-imprinting, electrochemical anodization and etching processes. Extracted protein yield was comparable to one obtained by chemical method. By properly tuning pulsed electric field, proteins can be extracted either by keeping cells alive or lysed. For the same protein yield, NS-EPEx chip can be operated at applied voltages of 4V and save energy by 2~3 orders of magnitude (0.12kJ/kg) as compared to the other methods (10~1,000 kJ/kg).

Oceli používané na výrobu plynovodů a ropovodů musí vykazovat specifické mechanické vlastnosti i za nízkých teplot, při kterých jsou citlivější ke křehkému porušení. U zkoušky padajícím závažím (DWTT) se použitelnost těchto ocelí posuzuje podle předepsané velikosti podílu houževnatého lomu (PHL) na lomové ploše DWTT tělesa při dané teplotě. Proto zásadním krokem této zkoušky je správně vyhodnotit PHL na lomové ploše. Existuje řada mezinárodních norem, například ASTM, GOST a ČSN, popisujících provedení a hodnocení výsledků této zkoušky, tj. určení PHL. Dosažené výsledky jsou závislé na použité normě a na vlastním posouzení hodnotitelem. Cílem této práce je zkoumat lomové plochy z DWTT těles pomocí fraktální analýzy. Pro dosažení tohoto cíle byl vytvořen algoritmus k určení fraktální dimenze lomových ploch. Zkoumání bylo provedeno na souboru DWTT těles z oceli X52. Výsledky fraktální analýzy byly porovnány s PHL získaným podle postupů z norem. Byla nalezena korelace mezi fraktální dimenzí lomových ploch a jejich PHL., Steels for gas and oil pipelines must represent specific mechanical properties in low temperatures, in which they are sensitive to brittle fracture. In case drop weight tear test (DWTT) application of these steels is assessed by percentage of ductile fracture on fracture surface of DWTT specimens. Therefore the essential step of this test is the proper evaluation of percentage of ductile fracture on fracture surface. There are a lot of standards which are describing the process of this test and analyzing results, for example ASTM, GOST, CSN. Obtained results are dependent on the standard, which was used and subjective view of expert, who tested specimens. The goal of this work is to examine the fracture surfaces of the DWTT specimens by using fractal analysis. To achieve this goal was made an algorithm, which determinate fractal dimension of surfaces. Evaluation was made on DWTT specimens, fabricated by steel X52. Obtained results were compared with results by analysis according to standards. Also was founded correlation between fractal dimension of fracture surfaces and percentage of ductile component of fracture on fracture surface., Ve zpracování, Import 03/08/2012