Enhancing the Linear Dynamic Range in Multi-Channel Single Photon Detector beyond 7OD.

We present design, implementation, and characterization of a single photon detector based on 32-channel PMT sensor [model H7260-20, Hamamatsu]. The developed high speed electronics enables the photon counting with linear dynamic range (LDR) up to 10count/s per detector's channel. The experimental characterization and Monte-Carlo simulations showed that in the single photon counting mode the LDR of the PMT sensor is limited by (i) "photon" pulse width (current pulse) of 900ps and (ii) substantial decrease of amplitudes of current pulses for count rates exceeding 10 count/s.

Detection of multi-color fluorescent objects with single photon spectrometer.

Single photon counting is the most sensitive and accurate method for detection of very weak fluorescent signals obtained in many applications such as DNA sequencing, detection of biological reporters on micro-beads, detection of droplets in micro-fluidic systems, etc. In this paper we describe the use of single photon spectrometer for detection and characterization of very weak multicolor fluorescence produced by mixtures of various fluorescent dyes and quantum dots.

Highly sensitive revealing of PCR products with capillary electrophoresis based on single photon detection.

Post-PCR fragment analysis was conducted using our single photon detection-based DNA sequencing instrument in order to substantially enhance the detection of nucleic biomarkers. Telomerase Repeat Amplification Protocol assay was used as a model for real-time PCR-based amplification and detection of DNA. Using TRAPeze XL kit, telomerase-extended DNA fragments were obtained in extracts of serial 10-fold dilutions of telomerase-positive cells, then amplified and detected during 40-cycle real-time PCR.

Dynamic range of fluorescence detection and base-calling accuracy in DNA sequencer based on single-photon counting.

Recently, we developed a family of high-performance automated capillary DNA sequencing instruments based on a single-photon detection of fluorescently labeled DNA fragments. Our machines employ digital and broadband techniques, essential for achieving superior instrument sensitivity and dynamic range. In the present paper, we discuss limitations of the instrument's performance caused by the nonlinearity of single-photon detectors as well as methods for nonlinearity compensation which increase the detection dynamic range and base-calling accuracy.

Formation of a resistive region at the anode end in DNA capillary electrophoresis.

We have studied the formation of a resistive region in the capillary during DNA separation. This effect is caused by an unequal change in the mobilities of cations and anions at the interface between the running buffer solution and the capillary. We studied the motion of the resistive region boundary by sequential removal of portions of the affected capillary end.