For screening applications in pharmaceutical research and in environmental analysis, homogeneous ... more For screening applications in pharmaceutical research and in environmental analysis, homogeneous and heterogeneous phase assays are already well-established. The large number of samples to be examined requires the measurement of a multisample arrangement by means of parallel techniques which are improved by miniturization. This has the additional advantage of reducing the volume of samples and reagents, coming close to nanoliter
A variety of optical transducers is presented in the literature based on just a few given optical... more A variety of optical transducers is presented in the literature based on just a few given optical principles. Based on principles like microrefractometry and -reflectivity, a classification is approached, especially for sensors used in bioanalytics. Two methods are discussed in detail, which are favoured in the group known as integrated optical Mach-Zehnder interferometers and reflectometric interference spectroscopy (RIfS) . Recent applications as chemical sensors and biochemical probes in the fields of hydrocarbon monitoring and immunoreactions are demonstrated. Perspectives in routine interaction analysis, microstructuring of devices, direct detection of low-molecular-weight ligands, and parallel high-throughput screening are discussed. . ' Plenary lecture. 0925-4005/97/$17.00 0 1997 Elsevier Science S.A. All rights reserved Prrs0925-4005(97)00042-7 2 A. Brecht, G. Gauglitz/Sensors
Optimised layer systems for immunosensors based on the RIFS transducer
Fresenius Journal of Analytical Chemistry, 1994
Several approaches to direct affinity sensing are currently under investigation. Prominent approa... more Several approaches to direct affinity sensing are currently under investigation. Prominent approaches based on optical transducers are surface plasmon resonance (SPR), grating couplers and interferometers. In this paper, investigations on the reflectometric interference spectroscopy (RIFS), a transducer based on thin dielectric films, are presented and discussed. The main advantages of the RIFS transducer are its ruggedness, the small active area
Modified Surface for Carrying Out or Detecting Affinity Reactions
Validation of an optical immunoprobe for pesticide detection in natural water samples
Proceedings of SPIE - The International Society for Optical Engineering
ABSTRACT
<title>Spectral interferometric immunoassay with synthetic lipid-anchored polypeptide antigens</title>
Chemical, Biochemical, and Environmental Fiber Sensors IV, 1993
ABSTRACT
Reflectometric interference spectroscopy for direct affinity sensing
Frontiers in Biosensorics II, 1996
<title>Interferometric biochemical and chemical sensors</title>
Chemical, Biochemical, and Environmental Fiber Sensors VII, 1995
ABSTRACT
Theoretical and Experimental Detectivity of the RIFS-transducer in Affinity-sensing
Biosensors '94, 1944
<title>Array configurations based on read-out techniques</title>
Biomedical Sensors, Fibers, and Optical Delivery Systems, 1999
ABSTRACT
Resonant Energy Transfer Detection for Low Volume Immunoassay in Environmental Applications
Teubner-Reihe UMWELT, 1998
Modification of Glass Type Surfaces for Direct Immunosensing
Biosensors '94, 1994
<title>Multianalyte determination with a direct optical miltiantibody detection system</title>
Environmental Monitoring and Hazardous Waste Site Remediation, 1995
Sequence-specific detection and quantification of nucleic acids are central steps in many molecul... more Sequence-specific detection and quantification of nucleic acids are central steps in many molecular biology procedures which have also been transferred to chip-based procedures. Hybridization-based assays can be used to quantify and discriminate between DNA target sequences down to the level of single base mismatches. Arrays of DNA probes immobilized on a support enable simultaneous testing of multiple sequences of a single sample. DNA arrays can be produced either by in-situ synthesis of oligonucleotides or by immobilization of pre-assembled DNA probes. Covalent and directed immobilization improves the reproducibility and stability of DNA arrays. This is especially interesting with repeated use of transducers or chips. Procedures are described for effective covalent immobilization of pre-assembled amino-linked oligonucleotides, by use of ink-jet techniques, on a modified and heated glass surface, with addressable surface areas ranging from 0.01 mm2 to a few mm2. Almost immediate ev...
Many therapeutic drugs exert their effects by interaction with well defined molecular targets. In... more Many therapeutic drugs exert their effects by interaction with well defined molecular targets. Increasing knowledge in molecular biology allows identification of more and more molecular key compounds and in consequence a molecular approach to disease and therapy. As binding of drugs to their target compounds is a key event, binding assays with an appropriate target molecule are useful means for primary screening of novel substances. We have investigated the potential of thin film interference spectroscopy (RIFS) as a label free detection method for pharmaceutical screening in a binding inhibition assay. To meet the throughput requirements in pharmaceutical screening a parallel detection system based on imaging spectroscopy was constructed. Thrombin/thrombin inhibitor interaction was investigated as a model system. The thin film transducer was covalently modified with a thrombin inhibitor. Specific binding of thrombin and binding inhibition by inhibitor compounds could be observed. A test cycle of less than 10 min could be reached. The parallel setup allows the simultaneous detection of 96 binding curves and can reach a throughput of more than 10 6 samples per year.
Spectral interferometry is presented as a tool to monitor the swelling of polymers caused by orga... more Spectral interferometry is presented as a tool to monitor the swelling of polymers caused by organic gases or hydrocarbons in waste water as well as the adsorption and interaction of antigens and antibodies in immunoreactions. Modem diode-array technology allows the consequent observation of changes in optical pathlength on a fractional nanometer scale with subsecond repetition times. The theory of multiple-reflection principles in white-li&t interferometry determines the possibilities and limitations of this method. The optical set-up and some applications in gas sensing and label-free immunosensing are discussed with respect to the sensitivity, selectivity and limits of detection at present.
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Papers by Andreas Brecht