Ending the tuberculosis epidemic by 2030 is one of the goals of the United Nations. In 2020, around ten million cases were registered worldwide, around 1.5 million people died as a result of the disease. This makes tuberculosis the second deadliest infectious disease worldwide after Covid-19. Multi-resistant variants of the bacterium Mycobacterium tuberculosis are an increasing problem in diagnosis and thus in successful treatment, mainly due to a lack of laboratory infrastructure in developing countries. A national network of eight companies and non-university research institutions wants to counter this with the help of photonics and has its solution approaches presented at the kick-off meeting of the three-year FluoResYst project funded by the BMBF. The aim is to develop a compact detection system for multi-resistance in tuberculosis infections for rapid diagnosis and efficient treatment of those affected.

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

In order to counter multi-resistance from tuberculosis bacteria, suspected cases must be tested daily and, if the laboratory results are positive, treated and isolated quickly. As a rule, however, there is a lack of the necessary laboratory infrastructure and logistics, because 95 percent of tuberculosis diseases occur in developing and emerging countries. In the project “Time-resolved fluorescence detection for the integrated multi-parameter analysis of multi-resistances, for example in tuberculosis”, FluoResYst for short, the partners will develop an innovative method for accelerated diagnosis of multi-resistances of bacterial pathogens using the example of tuberculosis. The goal is a compact and cost-effective photonic point-of-care detection system that will also enable tuberculosis diagnostics outside of laboratories and thus quickly and directly on site.

Innovation: Combination of fast fluorescence effects with fast detectors

On the one hand, the innovative method is intended to shorten time-consuming manual laboratory steps for biochemical detection and already make them available in the device and, on the other hand, to achieve rapid detection and evaluation via integrated optoelectronic components.

The detection of the multi-resistance genes of the pathogen is based on a fluorescence quenching effect. The glow of a fluorescent dye that is coupled to a DNA fragment is suppressed by the binding of an antibody. If a sample with the gene segment you are looking for is added, this bond is broken and the DNA lights up.

In order to be able to detect fluorescence, the corresponding fluorescent dyes are excited with light of a specific wavelength and then emit light of a different wavelength, which is measured. In order to design the detection system cheaply, excitation and fluorescence light should not be differentiated by expensive optical filters, but by their decay times. The fluorescent dyes used for the quenching effect have very short afterglow times in the nanosecond range. In order to be able to measure the multi-resistance genes in a time-resolved manner, a very fast image sensor and an even faster laser that switches off in the picosecond range as the excitation light are required. New integrated circuits are being developed for both in the project. The image sensor is realized with new single photon avalanche diodes (SPAD). These highly sensitive photodiodes, which have so far mostly been used for applications in autonomous driving, can not only detect individual photons, but above all achieve the required measurement speeds up to the gigahertz range.

Platform also adaptable for other multi-resistance tests

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, leads to a new detection technology that greatly simplifies complex analyzes that were previously difficult to access and thus makes them widely accessible. The development of the platform will not only improve tuberculosis diagnostics and the determination of multidrug resistance, but also contribute to containing the disease through accelerated on-site diagnostics. Their adaptability to other multidrug resistance tests will also make it possible to optimize the diagnosis of other infections frequently affected by resistance phenomena.

Network partners are Lionex GmbH (network coordinator), IMMS Institute for Microelectronic and Mechatronic Systems, iC-Haus GmbH, X-Fab, Ditabis Digital Biomedical Imaging Systems AG, Fraunhofer Institute for Cell Therapy and Immunology, Department of Bioanalytics & Bioprocesses IZI-BB, the microfluidic ChipShop GmbH and the Institute for Molecular Diagnostics and Bioanalysis (IMDB) gGmbH.

The FluoResYst project is funded by the Federal Ministry of Education and Research as part of the photonics research funding program (funding code iC-Haus: 13N15808).