Pauline ZIMMER defended her PhD on Sept. 03rd, 2026.
Place : Amphitheatre 1bis in the W1 building of École Centrale de Lyon in Ecully
Jury :
Rapporteuses :
Hou-Broutin YANXIA, Directrice de recherche, SYMMES- CEA GRENOBLE
Aude BOLOPION, Directrice de recherche, Institut FEMTO-ST
Examinateurs :
Elise GHIBAUDO, Professeure des universités, IUT 1 de Grenoble
Pedro A. VASQUEZ, Professeur associé, Université de Seville
Encadrement :
Emmanuelle LAURENCEAU, Maîtresse de conférences HDR, Ecole Centrale de Lyon; directrice de thèse
Marie FRÉNÉA-ROBIN, Professeure des universités, Lyon 1 Université Claude Bernard; co-directrice de thèse
Julien Marchalot, Maître de conférences, INSA Lyon; co-encadrant de thèse
Abstract :
Waterborne phytopathogenic bacteria pose a significant threat to agricultural production and food security. Among them, bacteria of the genus Dickeya, responsible for potato soft rot, can spread at very low concentrations, making their early detection particularly challenging.
This thesis presents the development of a hybrid plasmonic biosensor combining surface plasmon resonance imaging (SPRI) and alternating-current electrokinetics (ACEK) to enhance the transport of bacteria toward the sensing surface. The gold surface of the SPR immunosensor is microstructured into electrodes to generate alternating-current electroosmosis (ACEO) and dielectrophoresis (DEP). These phenomena are investigated experimentally and through numerical simulations to identify the optimal operating conditions for bacterial preconcentration near the sensing surface.
Specific recognition of Dickeya relies on the oriented immobilization of antibodies through SPAAC click chemistry onto ethylene glycol-based antifouling layers. These surfaces are characterized using infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), fluorescence, and SPR to identify the functionalization strategy that maximizes antibody–bacteria recognition.
The integration of ACEK with SPRI enables the active preconcentration of bacteria and the specific detection of Dickeya at concentrations of approximately 10⁴ CFU/mL within a few minutes, representing an improvement of at least two orders of magnitude compared with conventional SPRI. This platform therefore opens promising perspectives for the rapid, label-free, and multiplexed detection of bacterial pathogens in agricultural irrigation systems.
Keywords: Immunosensor, Plant-pathogenic bacteria, Alternating current electroosmosis; Surface plasmon resonance, surface chemistry