BSD has over 20 years of experience in the development of diagnostic assays. The group is technology-oriented and has worked on all kinds of target components such as proteins (biomarkers, food allergens), specific RNA/DNA sequences, microorganisms, toxins, contaminants (antibiotics / pesticides), toxic plasticizers and other quality-determining substances.
To build these assays various technologies are available:
- Preparation and production of nanoparticles. Stable carbon conjugates are prepared for a black-on-white signal. Silica nanoparticles and sol-gels are produced from scratch, whereby fluorescent lanthanoid ligand complexes are being incorporated.
- Inkjet printing of biomolecules. A Scienion S3 microarrayer is available for printing droplets down to 100 picoliter on surfaces such as nitrocellulose and glass/polystyrene slides. In addition, microarrays are printed on lateral flow membranes and in the wells of microtiter plates yielding multi-analyte diagnostics, fully-automatable in the case of ELISA plates. Printing of biomolecules and nanoparticles (e.g. carbon nanotubes) on biosensor chips is done as well.
Rapid immunoassay platforms
BSD uses and develops the following rapid immunoassay platforms:
- Lateral Flow ImmunoAssay (LFIA); up to 4 lines; 10 min.
- Slide-based protein (antibody) microarray assays; generally 100 spots (10x10 arrays); 45 min.
- Lateral flow Microarray ImmunoAssay (LMIA); up to 25 spots; 10 min.
- Microarray-ELISA (MELISA); generally 64 spots per well (8x8 arrays); 45 min.
Detection is simple and cheap by performing flatbed scanning or digital photography and is followed by image analysis. Transferring (also wirelessly) the raw data to dedicated software yields the final results in minutes.
Lateral flow Microarray ImmunoAssay (LMIA)
The LMIA is a rapid, multi-analyte test platform, comparable to the well-known pregnancy hormone test kit, but with 25 separate spots instead of two lines. Each spot represents a single test. Hence, running one sample in LMIA will give signals for up to 8 different analytes, in duplo and including control spots. Detection of DNA/RNA amplicons is possible as well (Nucleic Acid LMIA; NALMIA).
The MELISA enables the simultaneous detection of up to 20 targets in one sample, i.e. in one well of an ELISA plate. By using carbon nanoparticles the procedure can be shortened to two-steps; a 30 min incubation of sample with nanoparticles conjugated to a fusion protein of neutravidin and alkaline phosphatase (AP) followed by a 10 min incubation step with AP substrate. The examples on the right show detection of specific amplicons derived from genes encoding E.coli O157 virulence factors.
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