Probe Attachment

The environmental appHcations of infrared spectrometry are many and varied. Many appHcations at industrial sites are analogous to those for on-line process analysis waste streams and recycling processes can be monitored in the same way. Commercial infrared stack-gas monitors are based on either an extractive probe attached to a long-path gas ceU or an open-path (across stack) configuration (69). Stack plume and flare monitoring can be done externally... 

Jeffcoat MK, Reddy MS Progression of probing attachment loss in adult periodontitis. J Periodontol 1991 62 185-189. 

Automatic interface detection probes attached near the intakes of both pumps provide an operating logic. The upper probe is adjusted to detect both air-product... 

The highest efficiency for probe attachment was found for the reaction of carboxylated probe with an aminosilane surface. However, the level obtained by simple adsorption (without the addition of ED AC) was equally as high (mean probe density = 600 to 700 fmoles/cm ). Conversely, the attachment of an amine-modified probe to a carboxyl surface was much less efficient (mean probe density = 300 fmoles/cm ). The least efficient coupling was obtained using aldehyde surfaces (mean probe density = 150 fmole/cm ). 

Liu and Rauch (2003) of Motorola investigated oligonucleotide probe attachment onto polystyrene (PS), polycarbonate (PC), polymethyl methacrylate (PMMA), and polypropylene (PP) plastic surfaces. They utilized three different immobilization processes SurModics surface modification solution (that allows attachment of adsorbed reactive groups to a surface by photoactivation of polymers at 254 nm). Pierce Reactive-Bind coating solution, and CTAB (cetyltrimethylammonium bromide, a cationic detergent). Not surprisingly, the microarray performances on these plastics varied. 

Figure 3.15 Oligonucleotide probe attachment with charged and uncharged spacer arms. (From Shchepinov, M.S. et al.. Nucleic Acid Res., 25(6), 1155-1161, 1997. With permission.)...

Table 3.2 Common Coupling Chemistries Employed for Nucleic Acid and Protein Probe Attachments... 

Liu, Y. and Rauch, C.B., DNA probe attachment on plastic surfaces and microfluidic hybridization array channel devices with sample oscillation. Anal. Biochem., 317, 76-84, 2003. 

Fig.9 Typical F/R vs. D curve between the PMMA brush (L = 87nm, Mn = 121700, Mw/Mn = 1.39) and the sUica probe (attached on an AFM cantilever). The arrowheads indicate critical distances is the equilibrium thickness at which a repulsive force is detectable, and Do is the offset distance beyond which the brush was no more compressible...

In atomic force microscopy (AFM), the sharp tip of a microscopic probe attached to a flexible cantilever is drawn across an uneven surface such as a membrane (Fig. 1). Electrostatic and van der Waals interactions between the tip and the sample produce a force that moves the probe up and down (in the z dimension) as it encounters hills and valleys in the sample. A laser beam reflected from the cantilever detects motions of as little as 1 A. In one type of atomic force microscope, the force on the probe is held constant (relative to a standard force, on the order of piconewtons) by a feedback circuit that causes the platform holding the sample to rise or fall to keep the force constant. A series of scans in the x and y dimensions (the plane of the membrane) yields a three-dimensional contour map of the surface with resolution near the atomic scale—0.1 nm in the vertical dimension, 0.5 to 1.0 nm in the lateral dimensions. The membrane rafts shown in Figure ll-20b were visualized by this technique. 

It is also possible that the properties of the solution induce some modifications of eq. (17). This is the case for example of a fluorescent probe attached onto a polyelectrolyte in this case, the high local concentration of ions strongly influences the rate constant so that eq. (17) is no longer valid. For one typical recent example of such a phenomenon with phenanthrene, see Morrison et al. (1996). 

Jullien, M., Garel, J-R., Merola, F. and Brochon J.-C. (1986). Quenching by acrylamide and temperature of a fluorescent probe attached to the active site of ribonuclease. European Biophysical Journal, 13, 131-137. 

In the latter case, solution entering a vaporizer probe attached to the electrochemical cell is rapidly vaporized by resistive heating and sucked into the MS by the vacuum. Applications of ECMS have been in mechanistic analysis, and in the fields of electrocatalysis, batteries, sensors, and corrosion. 

Femoral blood flow and coronary flow are measured with electromagnetic flow probes attached to the femoral artery and the circumflex branch of the left coronary artery (LCX), respectively. 

In addition to the originally described method, it is possible to measure blood flow by means of an ultrasonic flow probe, attached distally to the position of the cotton threads on the vein. 

An interesting new approach to DNA detection involves probes attached to polymer microspheres loaded with a scintil-lant (25). The hybridization of a complementary, radiolabeled target DNA leads to strong signal amplification because of the close proximity of the scintillant and the radiolabel. Another appealing aspect of this method is that the PNA probe can be synthesized directly on the scintillant-loaded microspheres. 

Another appealing technique used often to image lipid structures is fluorescence microscopy and imaging (24). By using fluorescent probes attached covalently to lipid molecules, the fluorescence microscopy provides a wealth of spatially resolved... 

The amino acid module performs the dissolution, activation, and delivery of amino adds to the synthesis cabinet. This is accomplished via a robotic arm with a probe attachment. Liquids can be dispensed or withdrawn from amino acid vials through the probe. In addition, nitrogen can be bubbled to aid in the dissolution of the amino acid. After each amino acid coupling the probe is thoroughly washed, both internally and externally, to eliminate cross contamination. The amino acid module can hold up to 72 anoino acids in three 24-position racks. A rack can be assigned to each colunm or all 72 can be used for single column synthesis. 

Figure 5. Self-assembled monolayers as rigid electrochemical spacers. Close packing of the SAM enforces a precise distance between the redox probes and the electrode. (A) In a tethered redox probe system, the probes are covalently attached to the outer surface of the monolayer. The probes may be undiluted (a probe attached to each chain in the monolayer) or mixed (probe-modified chains are diluted with nonelectroactive chains). (B) In a soluble redox probe system, the monolayer typically contains a single component that provides a well-defined separation between the soluble probe and the electrode surface.

Several simplifying cases may now be considered. In general, for excitation into the lowest singlet state, the absorption and emission dipoles are parallel. This condition will be assumed in the following discussion. For a typical experiment in which a macromolecule is labelled with a fluorescent probe attached to random sites, the expression for r(t) is reduced to... 

---