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J&uuml;rgen Wolfrum

Karl-Heinz Drexhage

In order to carry out optical detection and identification of individual tumor markers in undiluted blood plasma, said tumor markers are marked with fluorescent dyes which are characterized by specific fluorescent lifetimes ranging from 0.5 to 6. The blood plasma is exposed to pulsed diode laser radiation emitted in the 630 to 670 nm wavelength range. The emission wavelengths of the dyes are selected in such a way that they are 10 to 60 nm longer than the wavelength of the diode laser. Blood plasma decay curves are detected using time-correlated single photon counts. Said curves are described by a bi-exponential model wherein it is assumed that a fixed fluorescent lifetime for blood plasma emission is 300 ps and that the marked tumor markers have a variable fluorescent lifetime. The relative amount of fluorescent photons in the marked tumors is determined in relation to the overall number of photons detected. If this value exceeds 0.3, a tumor marker is present in the observed volume. The tumor markers can also be identified by the lifetimes which are determined through bi-exponential evaluation. In this manner, individual tumor markers can be detected and identified in undiluted blood plasma.

Method for optical detection of analyte molecules in a natural biological medium

An extended fibre point (,) is coated with photbiotin and irradiated with U.V. light, causing the photobiotin to bind with the fibre pint. The fibre point is then brounght into contact with streptavidin and submerged in a solution containing dyed copies of the DNA molecule to be sequenced. Biotin is also bonded to the 5&prime; end of the dyed DNA molecules (,A). the biotin coupled to individual DNA molecules binds with the streptavidin at the fibre point. Light is coupled into the fibre to detect the thus obtained bonds. The evanescent field of said light excites a dyed DNA molecule to emit fluorescent light as soon as it binds with the fibre point. When a bond is deteccted, the fibre is immediately remvoded from the solution, and the fibre point is inserted into a microcapillary (,). The microcapillary is filled with a buffer solution containing exonucleases which decompose the DNA colecule base after base. The outlet (,) of the capillaries is located in the observation zone of individual molecule detection equipment. In order to improve the signal-noise ratio for individual molecule detection, the walls of the microcapillaries have a thickness in the area of their outlet which is distinctly smaller than &frac14; the wavelenght of the exciting light.

Growing community of inventors

Rosdorf, Germany

Jürgen Wolfrum

Growing community of inventors

Rosdorf, Germany

J&uuml;rgen Wolfrum

Jürgen Wolfrum