Cellular Binding and Internalization
of Functionalized
Silicon Nanowires
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Abstract
Nanostructures with precise control of sizes and shapes,
intrinsic
read-out signals for tracking, and flexible surface chemistry for
bioconjugation can offer an excellent system to study interaction
between nanomaterials and cells. In this paper, a new nanobio system
based on functionalized silicon nanowires (SiNWs) was developed. Using
the intensive and intrinsic nonlinear optical signal of SiNWs, we
visualized the interaction between the folate and amine group functionalized
SiNWs and cells by monitoring the cellular binding and uptake of SiNWs
in real time. We demonstrated that the strong specific ligand–receptor
interaction between folate on NWs and folate receptors on CHO-β
cell membranes expedited agglomeration of folate modified SiNWs on
cells and internalization of NWs. Such specific targeting was further
confirmed through control experiments done with normal CHO cell without
folate receptors. Weaker nonspecific 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. In addition, we also observed
the binding was independent of length for NWs ranging between 2.5
and 8.0 μm. Uptake of NWs highly depended on length and NWs
longer than 5 μm were difficult to be internalized. Our results
provided an insight of cellular interaction with 1-dimensional nanomaterials