The goal of this research group is to investigate biosensors and integrate them into point-of-care and benchtop devices. Biosensors are powerful tools for developing biological analysis devices with improved performance. Depending on the transducer, four major classes of biosensors exist: optical, electrochemical, mass-based and magnetical sensing. The latter three are currently being studied in this group.
LFA (Lateral Flow Assay) is a mature point-of-care diagnostics technology already used worldwide both in healthcare (e.g. pregnancy test, Covid self-test), agro-food and environment (e.g. milk contaminants) thanks to their user friendly and convenient format (no need of bulky equipment). More generally, paper-based analytical devices gain in popularity in the development of future on-site detection. However, they lack performance (sensitivity, limit of detection) and quantitative analysis.
This technology relies on the unidirectionnal capillary flow of the sample through a series of sequential paper pads. Each of the papers has different microstructures (pores) and functionalities (biointerfaces), aiming to generate a signal to indicate the absence/presence of the target analyt through the colour emitted by gold nanoparticles (AuNP). In our group, we are designing and developping LFA applications through the optimization of its multiple, interconnected parameters, with the goal to keep a user-friendly operation.
Although antibodies are still the "gold standard" for bio-interfaces in LFA, they have shown limitations for their use as diagnostic tool (low specificity and stability, high price,...). To circumvent these problems, we propose the use of bacteriophage proteins in LFA for the highly specific capture and detection of pathogens (e.g. Bacillus thuringiensis).
Paper-based microfluidic devices overcome the one-directional flow limitation of lateral flow assays to achieve complex and innovative architectures. From that, different functions can be formed with many possibilities for sampling (e.g. multiplexing, sample pre-treatment, stationary flow rate, blood separation, …). It can be seen as a whole laboratory integrated on a single Paper Chip. The paper-based microfluidic research focuses on the development of both new functionalities and on the deep understanding of microfluidic (e.g. modelling, fabrication methods, experimental measurements) for future integration in point-of-care devices.
An example of previous work is the development of a battery based on paper and water, which required a staionnary flow rate
The research group is also leveraging its scientific expertise in the design and characterisation of impedimetric and capacitive microelectronic biosensors to integrate dielectric (impedimetric) characterization of cellulose-based substrates towards the electrical detection of pathogens on paper.
Due to the unique advantages of using magnetic nanoparticles (MNP) for sample pretreatment, and the negligible magnetic background of biological samples, magnetic biosensor methods are considered to be promising tools for Point-of-Care biodetection. We develop lateral flow assays with magnetic nanoparticles and a volumetric magnetic sensor that can exactly quanitify how much MNP are present at the test- or control-line, thus enabling precise quantification of the analyte present in the sample.
Finally, electrochemical detection monitors the change of electrical properties associated with analyte binding at the surface of an electrode. This method, contrary to impedimetric and magnetic detection presented above, is a label-free detection method resulting in easier quantitative analysis. However, new challenges appear, namely the lower emitted signal and the reusability of the electrodes. Our research group focuses on these two challenges by investigating microfabrication and modelling, in order to achieve a blood biosensor for medical applications.
Application of the optical detection of bacteria from their lysate.
In order to improve limit of detection of porous silicon biosensors, the surface enhanced raman spectrosocpy (SERS) is investigated. SERS is a powerful bio-molecular characterisation technique that significatively amplifies the signal of an analyte by several orders of magnitude without using any label. To this end, the biosensor have to be decorated with plasmonic nanostructures. These plasmonic nanostructures (synthetized in the MOST laboratory) are composed of gold, silver or copper nanoparticles with different controlled morphologies (nanorods, branched nanostars, nanodentrites etc.). This anisotropy allows to increase locally the electric field at the tips of these nanostructures. FEM simulations on COMSOL are done alongside with experiments to combine theory with experiments.
Our research group benefits from the pluridisciplinal resources and skills available in different technological platforms of UCLouvain which are necessary for the success ofour projects :
This complementarity and proximity with the different platforms on the same site encourages fruitful collaborations. Many research groups, spin-offs and SMEs take advantage of these technological platforms to carry out their sensor tests or to characterize their characterization of their nanomaterials.