This paper presents a stochastic theory for the interpretation of photon counting histograms in fluorescence fluctuation spectroscopy (FFS). New concepts of an effective volume and a single molecule probability distribution are introduced to characterize a molecular species. Whereas the effective volume corresponds to the visibility of a molecular species in a given confocal setup, the single molecule probability distribution gives the signal measured for a single visible molecule. Specific properties of the effective volume and the single molecule probability distribution are discussed. Advantages arise for the high precision measurements of concentrations, mixtures, and binding constants especially for complex molecular environment, e.g. in flow systems and cell compartments.
In this paper we present a novel highly sensitive detection system for diagnostic applications. The system is designed to
meet the needs of medical diagnostics for reliable measurements of pathogens and biomarkers in the low concentration
regime. It consists of a confocal detection unit, micro-structured sampling cells, and a "Virtual lab" analysis software.
The detection unit works with laser induced fluorescence and is designed to provide accurate and highly sensitive
measurement at the single molecule level. Various sampling cells are micro-structured in glass, silicon or polymers to
enable measurements under flow and nonflow conditions. Sampling volume is below one microliter. The "Virtual lab"
software analyzes the light intensity online according to the patent pending "Accurate Stochastic Fluorescence
Spectroscopy" (ASFS) developed by FluIT Biosystems GmbH. Tools for simulation and experiment optimization are
included as well. Experimental results for various applications with relevance for in vitro diagnostics will be presented.
The interdisciplinary project IMIKRID targets the "proof of concept" of a novel technological platform for the development of customised complete diagnostic systems of ultra high sensitivity for in-vitro diagnostics. For this purpose, an integrated microfluidic diagnostic platform is developed and its application concerning diagnostic problems in the area of oncology and cardiovascular diseases as well as in environmental applications will be demonstrated.
This work focuses on the development of an online programmable microfluidic bioprocessing unit (BioModule) using digital logic microelectrodes for rapid pipelined selection and transfer of DNA molecules and other charged biopolymers. The design and construction technique for this hybrid programmable biopolymer processing device is presented along with the first proof of principle functionality. The electronically controlled collection, separation and channel transfer of the biomolecules is monitored by a sensitive fluorescence setup. This hybrid reconfigurable architecture couples electronic and biomolecular information processing via a single module combination of fluidics and electronics and opens new fields of applications not only in DNA computing and molecular diagnostics but also in applications of combinatorial chemistry and lab-on-a-chip biotechnology to the drug discovery process. Fundamentals of the design and silicon-PDMS-based construction of these electronic microfluidic devices and their functions are described as well as the experimental results.