On June 18, 2026, Gazy Khatmi, a doctoral student at Kaunas University of Technology, defended his doctoral dissertation “Photophysical Synthesis of Plasmonic Nanostructures and Their Applications in Lateral Flow Immunoassay Biosensors” in the field of Natural Sciences, Physics.
The dissertation focused on enhancing the sensitivity and limit of detection of lateral flow assays dedicated to the detection of SARS-CoV-2 and bacterial β-lactamases. This was achieved by employing photophysically synthesized ligand-free nanomaterials, delaying capillary flow wicking in nitrocellulose membranes, and performing digital colorimetric signal readout analysis.
Ligand-free Au, Pt, and Pt–Au nanoparticles produced by pulsed laser ablation in water were investigated as clean optical labels for rapid point-of-care diagnostics. The nanoparticles were characterized using dynamic light scattering, electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and transient absorption spectroscopy to evaluate their size, stability, composition, crystallinity, optical response, and ultrafast relaxation dynamics.
In β-lactamase lateral flow immunoassays, laser-synthesized Au, Pt, and Pt–Au nanoparticles enabled detection down to 1 ng/mL, showing improved low-concentration performance compared with commercial gold labels. The work also demonstrated that femtosecond laser micromachining of nitrocellulose membranes can delay capillary flow and enhance assay sensitivity by approximately 40%.
Machine-learning-based image analysis was applied for objective lateral flow test-line detection and quantification, supporting more reliable evaluation of weak biosensor signals.
This research was conducted at Kaunas University of Technology under the supervision of Prof. Dr. Tomas Tamulevičius, with important contributions from the Institute of Biotechnology, Life Sciences Centre, Vilnius University, particularly in the development and application of lateral flow immunoassay biosensors.
