Photonic point-of-care detection system instead of laboratory diagnostics.

To counter multiple drug-resistant tuberculosis bacteria, suspected cases must be tested daily, and if laboratory findings are positive, quickly treated and isolated. However, the laboratory infrastructure and logistics required are usually lacking, as 95 percent of tuberculosis cases occur in developing and emerging countries. In the project "Time-resolved fluorescence detection for integrated multiparameter analysis of multiresistance exemplified by tuberculosis" (FluoResYst), the partners will develop an innovative method for accelerated diagnostics of multiresistant bacterial pathogens using tuberculosis as an example. The goal is a compact and cost-effective photonic point-of-care detection system that will enable tuberculosis diagnostics to be conducted outside laboratories and thus quickly and directly in the field.

Innovation: Combination of fast fluorescence effects with fast detectors.

The innovative method is designed to shorten complex manual laboratory steps for biochemical detection and make them available already in the instrument, on the one hand, and to achieve rapid detection and evaluation via integrated optoelectronic components, on the other.
The detection of the multi-resistance genes of the pathogens is based on a fluorescence quenching effect, suppressing the glow of a fluorescent dye coupled to a DNA fragment through the binding of antibodies. If a sample with the gene segment of interest is added, this binding dissolves and the DNA lights up.
To detect fluorescence, the corresponding fluorescent dyes are excited with light of a certain wavelength followed by the emission of light of a different wavelength, all of which are measured. To design the detection system cost-effectively, excitation and fluorescence light are to be distinguished by their decay times rather than by expensive optical filters. The fluorescent dyes used for the quenching effect have very short afterglow times in the nanosecond range. In order to measure the multiresistant genes with time resolution, a very fast image sensor and an even faster laser as excitation light, which switches off in the picosecond range, are required. For both, new integrated circuits are being developed within the project. The image sensor is realized with new single-photon avalanche diodes (SPAD). These highly sensitive photodiodes, which have so far been used mostly for applications in autonomous driving, can not only detect single photons but above all achieve the required measurement speeds up to the gigahertz range. 

Platform adaptable for other multi-resistance detection applications

The combination of these two innovations, the biochemical fluorescence quenching antibody assay with the photonic integration of time-resolved fluorescence measurement for short-lived fluorochromes, results in a new detection technology that greatly simplifies complex analyses previously only accessible at great expenses, making them widely accessible. Thus, the development of the platform will not only improve tuberculosis diagnostics and the determination of multidrug resistance but also contribute to the containment of the disease by accelerating on-site diagnostics.  Its adaptability to other multidrug resistance detection will also enable the optimization of diagnostics for other infections frequently affected by resistance.

Collaborative partners are LIONEX GmbH (collaborative coordinator), IMMS Institut für Mikroelektronik- und Mechatronik-Systeme gemeinnützige GmbH (IMMS GmbH), iC-Haus GmbH, X-FAB, DITABIS Digital Biomedical Imaging Systems AG, Fraunhofer Institute for Cell Therapy and Immunology, Institute Division Bioanalytics & Bioprocesses IZI-BB, microfluidic ChipShop GmbH and the Institute for Molecular Diagnostics and Bioanalytics (IMDB) gGmbH.