Nanobiosensorics “Lendület” research group
Head of group: Dr. Róbert Horváth
The Nanobiosensorics Research Group focuses on the development and application of label-free optical biosensors and combines these technologies with single cell manipulation techniques. Their research topics are ranging from the kinetics of cellular adhesion, migration and signalling on novel biomimetic interfaces to the mathematical modelling of the measured biological signals. In 2019 they reached the following results:
- They demonstrated that a computer controlled micropipette (CCMP) is a straightforward and high-throughput alternative to quantify the surface adhesion of functionalized microparticles. They attached polystyrene microbeads to a solid support by the avidin-biotin linkage and measured the adhesion strength of the microbeads with both a specialized robotic fluid force microscope (FluidFM BOT) and CCMP.
- The fluidic force microscope (FluidFM) can be considered as the nanofluidic extension of the atomic force microscope (AFM). In another work, their aim was to investigate the calibration accuracy of certain parameters (the inverse optical lever sensitivity (InvOLS) and the spring constant (k)) and their dependence on: (1) the aperture size (2, 4 and 8 µm) of the hollow micropipette type cantilever; (2) the position of the laser spot on the back of the cantilever; (3) the substrate used for calibration (silicon or polystyrene). It was found that both the obtained InvOLS and spring constant values depend significantly on the position of the laser spot. Their proposed method helps in reducing the error introduced via improper calibration and thus increases the reliability of subsequent cell adhesion force or elasticity measurements with FluidFM.
- Optical Waveguide Lightmode Spectroscopy (OWLS) is widely applied to monitor protein adsorption, polymer self-assembly, and living cells on the surface of the sensor in a label-free manner. Typically, to determine the optogeometrical parameters of the analyte layer (adlayer), the homogeneous and isotropic thin adlayer model is used to analyse the recorded OWLS data. However, in most practical situations, the analyte layer is neither homogeneous nor isotropic. Therefore, the measurement with two waveguide modes and the applied model cannot supply enough information about the parameters of the possible adlayer inhomogeneity and anisotropy. This year, they construct an inhomogeneous adlayer model, where the adlayer covers the waveguide surface only partially and it has a given refractive index profile perpendicular to the surface of the sensor. Using analytical and numerical model calculations, the step-index and exponential refractive index profiles are investigated with varying surface coverage’s from 0 to 100%.
- This year, their aim was to investigate the effects of antioxidant superoxide dismutase (SOD)-like enzyme substituting metal complex systems on cell processes by applying novel, label-free biosensor method. SALEN- and SALAN-based complexes with catalytically active metal centres are very promising small molecules to be utilized as part of antioxidant therapies. In their novel study, they discussed a modified SALAN-type molecule armed with two phosphonate groups that significantly increase its water solubility and aid to furnish mono- or dinuclear complexes with Cu2+ ions. They reported that phosphonate groups affect coordination of Cu(II) to a SALAN ligand and increase water solubility. Furthermore, SOD-like activity and overall cell toxicity are both affected by Cu/ligand ratio. The SOD-mimc 1Cu/ligand complex is well tolerated by living cells.
- With scientists from the Semmelweis University and ELTE, they reported a quick, reliable and sensitive test that may fill an existing gap in EV standardization. When using the optimised lipid assay reported in their study, EV lipid measurements can be more reliable than protein-based measurements. Furthermore, this novel assay is almost as sensitive and as easy as measuring proteins with a simple BCA test.
- Micropatterning of living single cells and cell clusters over millimetre–centimetre scale areas is of high demand in the development of cell-based biosensors. Micropatterning methodologies require both a suitable biomimetic support and a printing technology. In their recent study, we presented the micropatterning of living mammalian cells on carboxymethyl dextran (CMD) hydrogel layers using the FluidFM BOT technology. In contrast to the ultrathin (few nanometers thick in the dry state) CMD films generally used in label-free biosensor applications, they developed CMD layers with thicknesses of several tens of nanometers in order to provide support for the controlled adhesion of living cells.
Their newest review titled „A practical review on the measurement tools for cellular adhesion force” provides a guide to choose the appropriate technique to answer a specific biological question or to complete a biomedical test by measuring cell adhesion.