Fabrication and characterization of multimodal magnetic-fluorescent polystyrene nanowires as selective cell imaging probes

The work presented here describes the preparation of new fluorescent, magnetic polystyrene (PS) nanowires via vacuum assisted infiltration of porous anodised aluminium oxide (AAO) membranes. A polymer solution of high molecular weight PS in THF, superparamagnetic magnetite nanoparticles and coumarin-153 dye is used to create the nanowires (NW) within the 200 nm diameter membranes. NW released by membrane dissolution have a high aspect ratio and a curled 'bamboo' like structure to them. NW have been characterised by optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). These wires were strongly luminescent and show good response to an external magnetic field. VSM measurements of these samples have shown presence of both superparamagnetic (SPM) and non-superparamagnetic components. The biological application potential of NW was also investigated by functionalising them with primary and secondary antibodies and incubation with epithelial lung cancer cells (A549 cell line). NW showed binding affinity to the surface of the cells and also endocytotic internalisation in the case of short wires. These structures have good potential for use in bio-medical imaging and diagnostic applications due to their additional modalities linked to their intrinsic material properties.