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sFIDA – particles count

Dr Oliver Bannach, Forschungszentrum Jülich GmbH; Prof. Dieter Willbold, Forschungszentrum Jülich GmbH; Dr Christian Zafiu, Forschungszentrum Jülich GmbH; Dr Andreas Kulawik, Forschungszentrum Jülich GmbH

Forschungszentrum Jülich GmbH


Protein misfolding is a common hallmark of many neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD) and prion diseases. Mounting evidence argues that especially smaller aggregates, so called oligomers, are the pathological culprits in these proteinopathies. Therefore the pathological oligomers might be the most direct and reliable biomarker of the respective disorder. To quantify oligomers in body fluids like blood plasma and cerebrospinal fluid (CSF), however, two major technical challenges have to be addressed: i) the extremely low concentration of oligomers and ii) the ubiquitous presence of an excess of monomers.


sFIDA stands for surface-based fluorescence intensity distribution analysis and is a platform technology for quantitation and sizing of single protein aggregates, e.g. single oligomers of amyloid beta, alpha-synuclein and prion protein, respectively. sFIDA combines the selectivity of an immunological assay with the sensitivity of high-resolution fluorescence microscopy. First, protein aggregates are captured from the sample and fixed to a glass surface. After unbound sample components are removed, detection antibodies labeled with two fluorescent dyes are added. A laser focus scans the surface and the highly decorated aggregates show bursts of fluorescent light in two color channels. It features single particle sensitivity, absolute specificity for aggregates and a 4 log dynamic range of size and concentration.

Commercial Opportunity

The sFIDA assay can be employed for biomarker-based monitoring of therapeutic success in drug trials and further adapted for differential diagnostics of other protein misfolding diseases. The technology can be applied to oligomer based diagnostics of Alzheimer’s and Parkinson’s disease as well as counting of single viral particles. Furthermore, sFIDA is perfectly suited for development and QC of biologicals.

Development Status

The assay is currently in the process of validation and optimization for the demands of high-throughput measurements.

Patent Situation

8 patent applications filed (PCT).

Further Reading

Surface-based fluorescence intensity distribution analysis (sFIDA): Ein neues Verfahren zur Frühdiagnose der Alzheimerschen Demenz. Biospektrum 07.2015, DOI: 10.1007/s12268-015-0642-3


sFIDA – particles count