Efficient targeting of fatty-acid modified oligonucleotides to live cell membranes through stepwise assembly.

Lipid modifications provide efficient targeting of oligonucleotides to live cell membranes in a range of applications. Targeting efficiency is a function of the rate of lipid DNA insertion into the cell surface and its persistence over time. Here we show that increasing lipid hydrophobicity increases membrane persistence, but decreases the rate of membrane insertion due to the formation of nonproductive aggregates in solution. To ameliorate this effect, we split the net hydrophobicity of the membrane anchor between two complementary oligonucleotides. When prehybridized in solution, doubly anchored molecules also aggregate due to their elevated hydrophobicity. However, when added sequentially to cells, aggregation does not occur so membrane insertion is efficient. Hybridization between the two strands locks the complexes at the cell surface by increasing net hydrophobicity, increasing their total concentration and lifetime, and dramatically improving their utility in a variety of biomedical applications.

Chemically programmed cell adhesion with membrane-anchored oligonucleotides.

Cell adhesion organizes the structures of tissues and mediates their mechanical, chemical, and electrical integration with their surroundings. Here, we describe a strategy for chemically controlling cell adhesion using membrane-anchored single-stranded DNA oligonucleotides. The reagents are pure chemical species prepared from phosphoramidites synthesized in a single chemical step from commercially available starting materials. The approach enables rapid, efficient, and tunable cell adhesion, independent of proteins or glycans, by facilitating interactions with complementary labeled surfaces or other cells. We demonstrate the utility of this approach by imaging drug-induced changes in the membrane dynamics of non-adherent human cells that are chemically immobilized on a passivated glass surface.