6 research outputs found
Recent advances in exciton based quantum information processing in quantum dot nanostructures
Recent experimental developments in the field of semiconductor quantum dot
spectroscopy will be discussed. First we report about single quantum dot
exciton two-level systems and their coherent properties in terms of single
qubit manipulations. In the second part we report on coherent quantum coupling
in a prototype "two-qubit" system consisting of a vertically stacked pair of
quantum dots. The interaction can be tuned in such quantum dot molecule devices
using an applied voltage as external parameter.Comment: 37 pages, 15 figures, submitted to New Journal of Physics, focus
issue on Solid State Quantum Information, added reference
Terbium to Quantum Dot FRET Bioconjugates for Clinical Diagnostics: Influence of Human Plasma on Optical and Assembly Properties
Förster resonance energy transfer (FRET) from luminescent terbium complexes (LTC) as donors to semiconductor quantum dots (QDs) as acceptors allows extraordinary large FRET efficiencies due to the long Förster distances afforded. Moreover, time-gated detection permits an efficient suppression of autofluorescent background leading to sub-picomolar detection limits even within multiplexed detection formats. These characteristics make FRET-systems with LTC and QDs excellent candidates for clinical diagnostics. So far, such proofs of principle for highly sensitive multiplexed biosensing have only been performed under optimized buffer conditions and interactions between real-life clinical media such as human serum or plasma and LTC-QD-FRET-systems have not yet been taken into account. Here we present an extensive spectroscopic analysis of absorption, excitation and emission spectra along with the luminescence decay times of both the single components as well as the assembled FRET-systems in TRIS-buffer, TRIS-buffer with 2% bovine serum albumin, and fresh human plasma. Moreover, we evaluated homogeneous LTC-QD FRET assays in QD conjugates assembled with either the well-known, specific biotin-streptavidin biological interaction or, alternatively, the metal-affinity coordination of histidine to zinc. In the case of conjugates assembled with biotin-streptavidin no significant interference with the optical and binding properties occurs whereas the histidine-zinc system appears to be affected by human plasma
Kohärente optische Eigenschaften einzelner Halbleiter-Quantenpunkte
von Stefan StuflerPaderborn, Univ., Diss., 200
Six-Color Time-Resolved Förster Resonance Energy Transfer for Ultrasensitive Multiplexed Biosensing
Simultaneous monitoring of multiple molecular interactions
and
multiplexed detection of several diagnostic biomarkers at very low
concentrations have become important issues in advanced biological
and chemical sensing. Here we present an optically multiplexed six-color
Förster resonance energy transfer (FRET) biosensor for simultaneous
monitoring of five different individual binding events. We combined
simultaneous FRET from one Tb complex to five different organic dyes
measured in a filter-based time-resolved detection format with a sophisticated
spectral crosstalk correction, which results in very efficient background
suppression. The advantages and robustness of the multiplexed FRET
sensor were exemplified by analyzing a 15-component lung cancer immunoassay
involving 10 different antibodies and five different tumor markers
in a single 50 μL human serum sample. The multiplexed biosensor
offers clinically relevant detection limits in the low picomolar (ng/mL)
concentration range for all five markers, thus providing an effective
early screening tool for lung cancer with the possibility of distinguishing
small-cell from non-small-cell lung carcinoma. This novel technology
will open new doors for multiple biomarker diagnostics as well as
multiplexed real-time imaging and spectroscopy