Interfacing nanostructures with biology has shown great promise for imaging and treatment of diseases. However, the translation of nanomedicine to clinical setting has been hampered by the limited fundamental understanding of the interactions between nanomaterials and cells. To establish this understanding, and thus enable rational design of nanomedicine, we aims at understanding the role of nanostructure in regulating cellular activities, as well as evaluating the potential of bio-conjugated nanostructures in therapeutic applications.In this work, we first performed the non-linear optical imaging study of silicon nanowires. This intensive and stable intrinsic optical signal from nanowires, together with depth resolution offered by non-linear optical imaging, enabled intravital imaging of nanowires for the first time. We demonstrated intravital imaging of nanowires circulating in the peripheral blood of a mouse and mapping of nanowires accumulated in organs.Using intensive and intrinsic nonlinear optical signal of SiNWs, we also visualized the interaction between the folate and amine group functionalized SiNWs and cells by monitoring the cellular uptake and intracellular distribution of SiNWs in real time. We found strong specific ligand-receptor interaction between folate on NWs and folate receptors on cell membranes greatly expedited agglomeration of folate modified SiNWs on cells and internalization of NWs. Weaker non-specific charge-charge attraction led to longer time required for amino group modified SiNWs to be bound on cell membrane. No effective accumulation was noticed for unmodified SiNW with native oxidized surface layer, which had the weakest dipole-charge interaction. Length effect of NWs on cellular response was also investigated. Our investigation suggested that silicon nanowire system provides an excellent system to study bio-interactions with 1-d nanomaterials, with its unparalleled capability in size and shape control, its intensive intrinsic nonlinear optical signal for imaging, and the flexible chemistry on silicon surface.

Functional silicon nanowires: A 1D nano-bio model system for drug delivery

248th National Meeting (2014)

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