Arrays in biological and chemical analysis.

Recently a dramatic change has happened for biological and biochemical analysis. Originally developed as an academic massive parallel screening tool, industry has caught the idea as well of performing all kinds of assays in the new format of microarrays. From food manufacturers over water supply plants to the omnipresent pharmaceutical industry, the buzz-word is bioarrays, attracting scientific funding and investor capital.

Quantification of small molecules using microarray technology.

Small molecule detection poses special problems during analysis whether hormones in a clinical setting or pesticides from environmental monitoring. Traditional analysis involves procedures like high-pressure liquid chromatography, gas chromatography, or mass spectrometry, or a combination of the three. Microarray procedures have recently evolved into a technique capable of replacing many of these assays, utilizing the strong and specific binding of a binder (e.

Optimization of oligonucleotide DNA microarrays.

Optimization of oligonucleotide DNA microarrays is a multiparametric problem. The goal of the optimization process is to get conditions that capture target DNA with high sensitivity and selectivity. Parameters determining the performance of the microarray are spot morphology, probe and target density, background, and selectivity.

Detection of mutations using microarrays of poly(C)10-poly(T)10 modified DNA probes immobilized on agarose films.

Allele-specific hybridization to a DNA microarray can be a useful method for genotyping patient DNA. In this article, we demonstrate that 13- to 17-base oligonucleotides tagged with a poly(T)10-poly(C)10 tail (TC tag), but otherwise unmodified, can be crosslinked by UV light irradiation to an agarose film grafted onto unmodified glass. Microarrays of TC-tagged probes immobilized on the agarose film can be used to diagnose mutations in the human beta-globin gene, which encodes the beta-chains in hemoglobin.

Transparent polymeric cell culture chip with integrated temperature control and uniform media perfusion.

Modern microfabrication and microfluidic technologies offer new opportunities in the design and fabrication of miniaturized cell culture systems for online monitoring of living cells. We used laser micromachining and thermal bonding to fabricate an optically transparent, low-cost polymeric chip for long-term online cell culture observation under controlled conditions. The chip incorporated a microfluidic flow equalization system, assuring uniform perfusion of the cell culture media throughout the cell culture chamber.

Immobilisation of DNA to polymerised SU-8 photoresist.

SU-8 is an epoxy-based photosensitive resist, which is currently used for a large variety of MEMS and lab-on-a-chip applications. Here, we demonstrate a one-step process to functionalize SU-8 with DNA probes. The immobilisation procedure relies on direct coupling of DNA to SU-8 and resulted in surfaces with functional capture probe densities of approximately 10 fmol/mm(2) as determined by hybridisation assays with fluorescent labelled target molecules.

Diagnostic and analytical applications of protein microarrays.

DNA microarrays have changed the field of biomedical sciences over the past 10 years. For several reasons, antibody and other protein microarrays have not developed at the same rate. However, protein and antibody arrays have emerged as a powerful tool to complement DNA microarrays during the past 5 years.

Use of culture, PCR analysis, and DNA microarrays for detection of Campylobacter jejuni and Campylobacter coli from chicken feces.

A DNA microarray for detection of Campylobacter spp. was recently developed and applied to detect Campylobacter spp. directly from chicken feces.

Characterization of an inexpensive, nontoxic, and highly sensitive microarray substrate.

An agarose film has been proposed as an efficient substrate for producing microarrays. The original film preparation procedure was simplified significantly by grafting the agarose layer directly onto unmodified microscope glass slides instead of aminated glass slides, and the blocking procedure was replaced with a wash in 0.1x standard saline citrate (SSC) and 0.

Quantitative microarray pesticide analysis.

To replace a pesticide immunoassay based on microtiter plates, we have developed a quantitative, competitive microarray immunoassay, which permits rapid and highly sensitive quantification of the dichlobenil degradation product 2,6-dichlorobenzamide (BAM), and the prominently used herbicide atrazine. The pesticide analysis is based on the competitive binding of fluorescence conjugated monoclonal antibodies (mAb) to their respective analytes. Lowest detection limits were calculated to 1 ng/l (5 pM) for BAM and 3 ng/l (10 pM) for atrazine.

Development of a multiplex microarray microsystem.

A hybrid multiplex microarray microsystem has been developed that consists of 32 individually addressable array reaction chambers, supporting the use of multichannel pipettes for addition of up to 8 samples simultaneously. Discrimination between Campylobacter jejuni and Campylobacter coli bacteria was observed in DNA samples containing Campylobacter spp., with the same specificity and sensitivity as when compared to a full-size microarray.

Detection of analyte binding to microarrays using gold nanoparticle labels and a desktop scanner.

Microarray hybridization or antibody binding can be detected by many techniques, however, only a few are suitable for widespread use since many of these detection techniques rely on bulky and expensive instruments. Here, we describe the usefulness of a simple and inexpensive detection method based on gold nanoparticle labeled antibodies visualized by a commercial, office desktop flatbed scanner. Scanning electron microscopy studies showed that the signal from the flatbed scanner was proportional to the surface density of the bound antibody-gold conjugates, and that the flatbed scanner could detect six attomoles of antibody-gold conjugates.

Quantitative assessment of factors affecting the sensitivity of a competitive immunomicroarray for pesticide detection.

Analytical protein microarrays offering highly parallel analysis can become an invaluable tool for a wide range of immunodiagnostic applications. Here we describe factors that influence the sensitivity of a competitive immunomicroarray that quantifies small molecules; in this case, the pesticides dichlobenil metabolite 2,6-dichlorobenzamide (BAM) and atrazine. Free pesticide concentrations in solution are quantified by the competitive binding of fluorescence-conjugated monoclonal antibodies to either surface-immobilized pesticide hapten-protein conjugates or pesticides in solution.

Development of a sensitive DNA microarray suitable for rapid detection of Campylobacter spp.

Campylobacter is the most common cause of human acute bacterial gastroenteritis worldwide, widely distributed and isolated from human clinical samples as well as from many other different sources. To comply with the demands of consumers for food safety, there is a need for development of a rapid, sensitive and specific detection method for Campylobacter. In this study, we present the development of a novel sensitive DNA-microarray based detection method, evaluated on Campylobacter and non-Campylobacter reference strains, to detect Campylobacter directly from the faecal cloacal swabs.

Adsorption kinetics and mechanical properties of thiol-modified DNA-oligos on gold investigated by microcantilever sensors.

Immobilised DNA-oligo layers are scientifically and technologically appealing for a wide range of sensor applications such as DNA chips. Using microcantilever-based sensors with integrated readout, we demonstrate in situ quantitative studies of surface-stress formation during self-assembly of a 25-mer thiol-modified DNA-oligo layer. The self-assembly induces a surface-stress change, which closely follows Langmuir adsorption model.