Superparamagnetic plasmonic nanoshells for improved imaging, separation and seeding of co-cultured cells

A human umbilical vein endothelial cell/human dermal fibroblast (HUVEC/HDF) co-culture system has been widely applied for mimicking the vascularization process in tissue engineering. Here, we have developed plasmonic superparamagnetic nanoshells (SNs) to realize the visualization of cell proliferation behaviour via two-photon luminescence of particle shells and the cell separation via the superparamagnetic properties of particle cores. The cell viability test and gene expression analysis have demonstrated no obvious cytotoxicity and disturbance to cell co-culture. Cell separation efficiency via SNs reaches a value of 94.7%, close to 99.5% in routine methods by magnetic beads. In contrast to the complicated and expensive process using specific antibody-targeted immunofluorescence staining and the magnetic beads separation in routine methods, SNs present a more simple and effective way to achieve both functions with better photo-stability and a negligible photo-bleaching effect via TPL imaging. Furthermore, the combination of the TPL imaging and magnetic manipulation of SNs also offers the potential of spontaneously enhancing the cell seeding and tracking the cell distribution in 3D tissue engineering scaffolds.