Biomedical subjects

Mikkel Noerholm

Publications and source records attributed to Mikkel Noerholm.

3 recordsLinked to original sources

PubMed2006

A sensitive array for microRNA expression profiling (miChip) based on locked nucleic acids (LNA).

MicroRNAs represent a class of short (approximately 22 nt), noncoding regulatory RNAs involved in development, differentiation, and metabolism. We describe a novel microarray platform for genome-wide profiling of mature miRNAs (miChip) using locked nucleic acid (LNA)-modified capture probes. The biophysical properties of LNA were exploited to design probe sets for uniform, high-affinity hybridizations yielding highly accurate signals able to discriminate between single nucleotide differences and, hence, between closely related miRNA family members. The superior detection sensitivity eliminates the need for RNA size selection and/or amplification. MiChip will greatly simplify miRNA expression profiling of biological and clinical samples.

Animals↗

PubMed2003

Polymer microfluidic chip for online monitoring of microarray hybridizations.

A disposable single use polymer microfluidics chip has been developed and manufactured by micro injection molding. The chip has the same outer dimensions as a standard microscope slide (25 x 76 x 1.1 mm) and is designed to be compatible with existing microscope slide handling equipment like microarray scanners. The chip contains an inlet, a 10 microL hybridization chamber capable of holding a 1000 spot array, a waste chamber and a vent to allow air to escape when sample is injected. The hybridization chamber ensures highly homogeneous hybridization conditions across the microarray. We describe the use of this chip in a flexible setup with fluorescence based detection, temperature control and liquid handling by computer controlled syringe pumps. The chip and the setup presented in this article provide a powerful tool for highly parallel studies of kinetics and thermodynamics of duplex formation in DNA microarrays. The experimental setup presented in this article enables the on-chip microarray to be hybridized and monitored at several different stringency conditions during a single assay. The performance of the chip and the setup is demonstrated by on-line measurements of a hybridization of a DNA target solution to a microarray. A presented numerical model indicates that the hybridization process in microfluidic hybridization assays is diffusion limited, due to the low values of the diffusion coefficients D of the DNA and RNA molecules involved.

Automation↗

PubMed2003

Microstructure fabrication with a CO2 laser system: characterization and fabrication of cavities produced by raster scanning of the laser beam.

In this paper we describe the use of a CO(2) laser for production of cavities and microstructures in poly(methyl methacrylate) (PMMA) by moving the laser beam over the PMMA surface in a raster pattern. The topography of the cavities thus produced is studied using stylus and optical profilometry and scanning electron microscopy (SEM). The microstructures display artifacts from the laser ablation process and we describe how the laser ablation parameters can be optimized in order to minimize these artifacts. Using this technique it is possible to generate structures with a depth from 50 microm and a minimum width of approximately 200 microm up to depth and widths of several mm, governed by the beam size and the laser settings.

Journal Article↗