Abstract - Coen

Supported Lipid Bilayers (SLBs) serve as versatile biomimetic platforms for investigating cell-membrane interactions due to their well-defined composition, fluidity, and compatibility with fluorescence microscopy. Magnetic Nanoparticles (MNPs) offer a unique tool for remote and reversible manipulation at the nanoscale. By coupling biofunctionalized MNPs with SLBs, we establish a well defined and controllable substrate where magnetic forces induce localized MNP accumulation, creating static and dynamic chemical gradients. SLBs were fabricated using the Langmuir-Blodgett Langmuir-Schäfer technique with SOPC or DPPC as matrix lipids, incorporating DOPE-cap-biotin as a linker lipid. Streptavidin-coated MNPs selectively bound to biotinylated lipids, enabling further functionalization with proteins of interest. A custom-built magnetic tip generated spatially controlled magnetic field gradients, allowing precise manipulation of MNP distributions. Experiments were conducted at room temperature, 37 °C, and 45 °C to explore temperature-dependent effects. Characterization of the magnetic tip revealed a well-defined force field that directed MNP accumulation. The variation in tip height allows differentiation of both the strength and concentration profile within the accumulated spot. Force profiles derived from accumulation dynamics aligned with force profiles of the magnetic tip. SOPC-based SLBs supported a permanently dynamic MNP state, where diffusion constants were extracted from relaxation dynamics. In contrast, DPPC-based SLBs exhibited temperature-responsive behavior, switching between static and dynamic states. This study demonstrates a tunable platform for controlling MNP distributions on SLBs, offering potential for biochemical applications such as magnetically induced protein gradients for selective pathway activation. Future work will focus on functionalizing MNPs with signaling proteins to investigate controlled cellular responses.