Parallel fabrication of DNA-aligned metal nanostructures in microelectrode gaps by a self-organization process.
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DNA↗
Biomedical subjects
Wolfgang Fritzsche
Publications and source records attributed to Wolfgang Fritzsche.
Optimization of gold nanoparticle-based DNA detection for microarrays.
DNA microarrays are promising tools for fast and highly parallel DNA detection by means of fluorescence or gold nanoparticle labeling. However, substrate modification with silanes (as a prerequisite for capture DNA binding) often leads to inhomogeneous surfaces and/or nonspecific binding of the labeled DNA. We examined both different substrate cleaning and activating protocols and also different blocking strategies for optimizing the procedures, especially those for nanoparticle labeling. Contact angle measurements as well as fluorescence microscopy, atomic force microscopy (AFM), and a flatbed scanner were used to analyze the multiple-step process. Although the examined different cleaning and activating protocols resulted in considerably different contact angles, meaning different substrate wettability, silanization led to similar hydrophobic surfaces which could be revealed as smooth surfaces of about 2-4 nm roughness. The two examined silanes (3-glycidoxypropyltrimethoxysilane (GOPS) and 3-aminopropyltriethoxysilane (APTES)) differed in their DNA binding homogeneity, maximum signal intensities, and sensitivity. Nonspecific gold binding on APTES/PDC surfaces could be blocked by treatment in 3% bovine serum albumin (BSA).
Base Sequence↗
Enzymatic control of metal deposition as key step for a low-background electrical detection for DNA chips.
Electrical detection of DNA using nanoparticle labels in combination with metal enhancement represents an interesting alternative to fluorescence readout schemes. This electrical method is hampered by unspecific metal deposition, resulting in a lower sensitivity of the assay. A novel enhancement technique based on an enzymatic process is introduced. This approach enables highly specific metal deposition only at the enzyme label, without the background that is typical in the case of the conventional metal enhancement process of growing nanoparticles. The enzymatic enhancement leads to a significant increase in sensitivity, and the detection of single base mismatches demonstrates the high specificity of the novel enhancement approach.
Biosensing Techniques↗
Nanoparticles for biotechnology applications.
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Biotechnology↗
Pearl chain formation of nanoparticles in microelectrode gaps by dielectrophoresis.
The integration of molecular structures into microscopic electrode arrays is achieved by dielectrophoresis of gold nanoparticles in electrode gaps. Using microelectrodes realized by photolithography, we demonstrate here the generation of pearl chain arrangements of nanoparticles in structures accessible for standard technologies. To preserve the individual particle structures in the final nanowire arrangement, various strategies were employed. An electrical characterization of the pearl chains yielded an Ohmic behavior. The effect of increased current on these structures is studied at the ultramicroscopic level.
Journal Article↗
Microstructured arrays with pre-synthesized capture probes for DNA detection based on metal nanoparticles and silver enhancement.
DNA microarrays exhibiting highly defined squared spot geometry and increased homogeneity in capture DNA distribution were prepared by a combination of microfabrication and DNA spotting. The microfabricated substrates were tested using metal nanoparticles as markers. The optical absorption signal is improved by a silver enhancement step. Experiments demonstrated the specificity and the concentration-dependency of the signal.
DNA↗
Gold nanoparticles as novel label for DNA diagnostics.
The growing interest in DNA diagnostics, especially in combination with the need for highly-paralleled and miniaturized hybridization assays, is today addressed by fluorescence DNA chips. Fluorescence detection is approved and highly developed, however, it has also problematic aspects, e.g., the low stability of the dyes, the influence of the physicochemical environment onto the signal intensity and the expensive set-up for detection. A novel detection scheme based on metal nanoparticles was proposed to overcome these problems and is discussed in this review.
DNA↗