Multiplex readouts

There are approximately 2700 compounds per primary screening mixture, and the readout is in essence multiplexed the ligands are individually ionized and identified in the mass spectrometer according to their exact mass positions. The readout, however, does not unambiguously identify compounds, as multiple compounds in a single mixture may have the same mass, i.e., a particular peak may correspond to as many as 31 compounds with closely related masses. The protein excess over individual compounds coupled with the rarity of potent ligands within a randomly assembled library minimizes competition between ligands for... 

It is more than probable that arrays for 50-100 DNA sequences will be needed for some clinical applications. Although it is not difficult to design electrode pads with reproducible dimensions of a micron or less, the electrochemical readout requires mechanical connections to each individual electrode. Therefore, the construction of very large, multiplexed arrays presents a major engineering challenge. Electronic switches in the form of an on-chip electronic multiplexer may provide a possible solution for this problem. 

Starting with the first IPCR study, gel electrophoresis retains its potential as a fast and easy method for end-point determination of DNA amplificate for IPCR assays [10, 24, 25, 29, 31, 35, 36, 38, 39, 64], Readout is performed by intercalation fluorescence markers (e.g., ethidium bromide) and photometric/densitometric quantification of band signal intensities. The direct addition of a double-strand specific intercalation marker to the PCR amplificate and subsequent measurement of fluorescence in microwells proved to be of insufficient sensitivity for the quantification of IPCR amplificate [37]. Alternative approaches, such as radioactive labeling during PCR and subsequent imaging [33], were carried out but are not well suited for routine clinical application because of additional methodological requirements. An advantage of gel electrophoresis is the possibility of simultaneous amplificate detection for multiplex IPCR [41] and the ability to detect nonspecific amplification products. 

Exploration of IRFPA sources in early 1994 revealed that several Defense Department contract manufacturers produced InSb (1-5.5 pm) and HgCdTe (or MCT for 2-12 pm) 256 x 256 and smaller arrays (<65, 536 total pixels on 30 pm centers) with built-in multiplexers for imaging projects (21). One requirement for pulsed spectroscopic applications is that an array be run in snapshot rather than normal imaging strobing readout format. This characteristic is necessary because a constantly strobing... 

In order to efficiently bioassay large compound arrays while preserving the integrity of the SAR information content of the spatial array, we have found that multiple, parallel, high-throughput bioassays are an attractive alternative. We will review several case examples of multiplexed bioassays with spatially-addressable chemical arrays and discuss issues related to data management, prevention of readout crosstalk and multiplexing of primary and secondary assays. 

In the first example we have multiplexed two primary bioassays that utilize different reporter systems, i.e., visible and/or fluorescence readout. In... 

In the second example, two primary, in vitro serine protease assays with identical /Miitroaniline-based chromogenic (A405) readouts were either assayed separately or multiplexed. Positive control inhibitors specific to each enzyme were added to the assay at an appropriate concentration to determine assay... 

FIC. 16.24 Readout results of the polarization-multiplexed recorded data at the respective recording polarization angles 0°, 60°, and 120°. 

The setup shown in Fig. 5.49 can, in principle, be used to record fast changes in the brain at 4 laser wavelengths and 32 detector positions. However, the limited speed of the fibre switch normally allows one to record sequences only for one or two source positions at a time. The result is a total number of 128 to 256 waveforms each 50 to 100 ms or 32 to 64 per TCSPC module. The corresponding readout rate in the memory swapping mode is well within the range of currently used TCSPC modules. However, improved fibre switches may allow one to multiplex a larger number of source positions at a rate of 100 s" or faster. The data transfer rate then exceeds 10 Mbyte/s, and precautions have to be taken to sustain this rate over a longer time. 

K.T. Tang, DJ. Yao, C.M. Yang, H.C. Hao, J.S. Chao, C.H. Li, P.S.Gu, A Portable Electronic Nose Based on Bio-Chemical Surface Acoustic Wave (SAW) Array with Multiplexed Oscillator and Readout Electronics. (ISOEN, Brescia, 2009)... 

H.C. Hao, et al., Development of a portable electronic nose based on chemical surface acoustic wave array with multiplexed oscillator and readout electronics. Sensors and Actuators B Chemical 146(2) 545-553 (2010)... 

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