Laser scanners

We have successfully used MALDI-TOF mass spectrometry to identify stacked 5-mers during CSH [10], Several samples of DNA were hybridised to different microchip-immobilised oligonucleotides in the presence of a 5-mer mixture. The molecular-mass differences among any of the four nucleotides — dAp (313.2 Da), dCp (289.2 Da), dGp (329.2 Da) and dTp (304.2 Da) — constitute at least 9 Da, which is easily resolved by using MALDI-TOF. 

---

Imaging plates are exposed similar to radiographic films. They are read out by a LASER-scanner to a digital image without any developing process. After optical erasing of the virtual picture the same IP can be used cyclic up to more than 1000 times. The life time is limited by the mechanical stability of the IP s. An IP consists of a flexible polymer carrier which is coated with the sensitive layer. This layer is covered with a thin transparent protective foil. 

P ) The system BAS 2000 (bio-imaging analyser) from Fuji Film. The system included flexible IP s, in a 20 X 40 cm and 20 X 25 cm format (type BAS ni) and an IP without proteetive layer (BAS-TR2040). With the system s laser scanner (flat bed) one can read these IP s with a resolution of 100 pm or 200 pm and a digital dynamie of 8 or 10 bits. The system is not on the market anymore. 

In a second experiment, Cy5-labelled antiBSA antibodies were immobilised on a silanised glass slide precoated with metallic nanoislands using a polydimethylsiloxane (PDMS) flow-cell. The antibody solution was left for 1 hour to attach and then the cell was flushed with deionised water. The slide was then dried with N2. For this experiment, a portion of the slide was not coated with metallic nanoislands, in order to act as a reference. Figure 20 shows the image recorded using the fluorescence laser scanner mentioned previously. The enhancement in fluorescence emission between those areas with and without nanoislands (B and A, respectively) is again evident. For both chips, an enhancement factor of approximately 8 was recorded. There is considerable interest in the elucidation and exploitation of plasmonic effects for fluorescence-based biosensors and other applications. 

In conventional chip experiments, fluorescence scanners are used for chip read-out. In the case of laser scanners, HeNe lasers are used as excitation sources and photomultiplier tubes as detectors, whereas CCD-based scanners use white light sources. The optical system can be confocal or non-confocal. Standard biochip experiments are performed using two fluorescent labels as... 

L. R. Middendorf, J. C. Bruce, R. C. Bruce, R. D. Eckles, D. L. Grone, S. C. Roemer, G. D. Sloniker, D. L. Steffens, S. L. Sutter, J. A. Brumbaugh and G. Patonay, Continuous, on-line DNA sequencing using a versatile infrared laser scanner/electrophoresis apparatus Electrophoresis 13, 487-494... 

Slide-based microarray technology was first introduced by Schena etal. (1995). The processes and equipment for preparing (arrayer) and analyzing (laser scanner) microarray slides comprised a portion of Dari Shalon s thesis work at Stanford University. Polymerase chain reaction (PCR) products (cDNA probes) were attached to PLL-coated glass microscope slides. The... 

Fragmented, biotinylated RNA prepared in this manner was hybridized to the array and the signal developed using streptavidin-R-phycoerytherin. A confocal laser scanner was used for detection. The researchers estimated that they could detect two transcripts per cell based upon labeling efficiency and an estimated 4% mRNA content in total bacterial RNA. Thus, chip detection of labeled transcripts was found to be more sensitive than detection by Northern blot. Specific genes (e.g., basal levels of cinA) undetectable on Northern blots were quantifiable on the microarray. In addition, it was... 

A modern and very exact method of growth rate measurements is the laser-scanner. The disadvantage of this method is, that it can only be used on the outside of tubes. In the industrial application the disadvantage is that by this method only one tube of a bundle of tubes can be measured at a time. 

The same accuracy as with the laser-scanner can be reached with thermocouples. However this is only a quasi-on-line measuring technique. The number of measuring points is limited by the number of thermocouples. The greatest disadvantage of this method is its interference during the build up of the crystal coat. 

Fig. 22 Basic set up of a laser scanner system for the read-out microarrays according to Schena [127]...

Middendorf, L.R., et al. (1992) Continuous, on-line DNA sequencing using a versatile infrared laser scanner / electrophoresis apparatus. Electrophoresis 13 487-94. 

The surface area of the natund fracture surface was measured using a 3-ditnensionai laser scanner (Inter Tech Co., Ltd). The surface area of the fracture surface was measured as 79.02 cm An experimental setup for the sur ce sorption experiments used in this study is shown in Hg. 1. 

When a computer prints to a laser printer, it sends a signal through a cable to the printer controller assembly. The controller assembly formats the information into a page s worth of line-by-line commands for the laser scanner. The controller sends commands to each of the components telling them to wake up and start the EP print process. 

The results herein demonstrated the successful application of parallel combinatorial methods to generate libraries of sensing SAMs covalently immobilized in the wells of a glass microtiter-plate. The fluorescence pattern after exposure of the array to different metal ion solutions allows identification of Cu2+, Co2+, Ca2+, Zn2+ and Pb2+ at 10"4 M concentration by laser confocal microscopy and fluorescence laser scanner. The collection of the unselective response of the monolayers in the presence of the cations generates a characteristic fluorescent pattern, a fingerprint of each analyte in the array. 

The methodology is highly compatible with existing formats, and if the laboratory already possesses the spotting robot and laser scanner, implementation is possible at very low cost It should be noted that the spotting and scanner facilities, as weU as other instrumentation, are not limited only to SNP analyses but may also be used for other purposes such as gene expression analyses. 

The extension substrate is an only 0.5 mm-thick composite structure of silicon and silica crystals forming regular capillaries with tube diameters below 10 pm. Extension oligonucleotides are immobilized within these capillaries, and are specific for each separate area on the chip. Once the extension solution containing the target strand is applied to one special SNP chip area, the sample is driven into the crystal by capillary forces and exposed to its complementary extension oligonucleotides. Annealing takes place inside the capillaries, and extension occurs due to the presence of dideoxynucleotides and DNA polymerase. Results can be read out with laser scanners at a resolution of about... 

RNA isolated from cells or tissue of interest and control samples are labeled with a fluorescent dye and allowed to bind in a quantitative manner to complementary sequences on the microarray. Relative expression fold of difference of the sequences in the test samples can be estimated by comparing the fluorescence intensities, measured by laser scanner, with those of the control samples. Data management and mining methods applied to microarray data analysis essentially have been correlation-based approaches that apply methods developed for the analysis of data that are more highly constrained than at the transcriptional level. 

---