For many medical applications, controlled interaction of cells with surfaces is desirable. For example, in the already clinically applied cell-sheet technology, cells detach from a polymer surface upon cooling, which causes the polymer to swell and become nonadhesive (1). On page 841 of this issue, Ohta et al. applied the same idea to the surface of colloidal nanoparticles (NPs) (2). In the adhesive state, in which ligands on the NP surface are accessible, the NPs specifically adhere to the surface of cells bearing a corresponding receptor and are internalized. In the nonadhesive state, the targeting ligands are inaccessible; the NPs do not show specific adhesion to cells and are internalized to a much lower extent. This switching is initiated by the presence of short oligonucleotide sequences, so NPs (and any cargo, such as drugs) could be targeted to cells on the basis of characteristic overexpressed oligonucleotides on cell surfaces.
Author: Wolfgang J. Parak