Based on biomolecular methods, rapid and selective identification of human pathogenic water organisms becomes an important issue. Legionella spp., are pathogenic water bacteria with worldwide significance. Prevalent detection methods for these microorganisms are time and/or cost intensive. We describe a detection setup and relating DNA assay. A miniaturized real‐time polymerase chain reaction (real‐time PCR) for direct on‐line discrimination of Legionella pneumophila and Legionella spp. was established and integrated into a real‐time PCR‐chip‐system. The PCR‐chip device combines a temperature controlling unit and a fluorescence intensity measurement. It was designed to achieve rapid amplification, using an approach of real‐time fluorescence read out with the intercalating dye EvaGreen® and melting curve analysis, without requiring multiple probes. The presented results exhibit reproducibility and good sensitivity, showing that the setup is suitable for robust, rapid and cost‐efficient detection and monitoring of a variety of Legionella spp.in urban water samples.

Novel point-of-care compatible methods such as colorimetric assays have become increasingly important in the field of early pathogen detection. A simple and hand-held prototype device for carrying out DNA-amplification assay based on plasmonic nanoparticles in the colorimetric detection is presented. The low-cost device with two channels (sample and reference) consists of two spectrally different light emitting diodes (LEDs) for detection of the plasmon shift. The color change of the gold-nanoparticle-DNA conjugates caused by a salt-induced aggregation test is examined in particular. A specific and sensitive detection of the waterborne human pathogen Legionella pneumophila is demonstrated. This colorimetric assay, with a simple assay design and simple readout device requirements, can be monitored in real-time on-site.

Biosensors are used for the specific and sensitive detection of biomolecules. In conventional approaches, the suspected target molecules are bound to selected capture molecules and successful binding is indicated by additional labelling to enable optical readout. This labelling requires additional processing steps tailored to the application. While numerous label-free interaction assays exist, they often compromise on detection characteristics. In this context, we introduce a novel diffractometric biosensor, comprising a diffractive biosensor chip and an associated optical reader assembly. This innovative system can capture an entire assay, detecting various types of molecules in a label-free manner and present the results within in a single, comprehensive image. The applicability of the biosensor is assessed for the detection of viral DNA as well as proteins directly in human plasma, investigating different antigens. In our experiments, we achieve a detection limit of 4.2 pg/mm², which is comparable to other label-free optical biosensors. The simplicity and robustness of the method make it a compelling option for advancing biosensing technologies. This work contributes to the development of an imaging diffractometric biosensor with the potential for multiple applications in molecular interaction analysis.

This microfluidic device for generic digital droplet-based bioassays (ddAssays) combines on-chip droplet generation and storage for droplet incubation and optical readout, due to its unique retainer structure.

The differential count of leukocyte subpopulations from peripheral blood smears remains a cornerstone of clinical hematology but relies on staining protocols or flow cytometry, that introduce variability and obscure native biochemistry. This study presents label-free workflows that distinguish leukocytes from erythrocytes in full blood smears and classifies the leukocyte subtypes as granulocytes, lymphocytes and monocytes using their single cell optical photothermal infrared (OPTIR) spectra. The first approach uses discrete wavenumber images using two key bands at 1546 and 2922 cm ^-1 to screen leukocytes. The second approach using intrinsic fluorescence imaging of leukocytes offers approximately 1000 times faster screening. Multiple OPTIR spectra are acquired per leukocyte followed by post-acquisition Giemsa staining for cytological cell verification. Full blood smears were prepared on calcium fluoride and standard glass slides to compare substrate effects, and OPTIR spectra were collected with 532 and 785 nm probe lasers to assess probe wavelengths effects. Principal component–linear discriminant analysis separated granulocytes from mononuclear subtypes under all substrate–probe laser combinations tested on the basis of lipid, nucleic-acid and protein bands in OPTIR spectra. Lymphocytes and monocytes were better distinguished on calcium fluoride than on glass. The OPTIR spectra stayed stable over 14 days of storage on both substrates, whereas the intrinsic fluorescence used for cell localization was weak in fresh smears and increased with storage. The non-destructive, fixation-free measurement preserves native protein and lipid composition and allows subsequent cytological staining, supporting OPTIR on routine glass slides for future label-free hematological screening.