Metabolic delivery of methacryloyl groups on living cells and cell surface modification via thiol-ene "click" reaction.

Methacryloyl groups are delivered on a living cell surface via a glycosylation pathway. The mannosamine derivative ManMA is synthesized as a precursor of cell-surface sialic-acid residues. HeLa cells are cultivated in a culture medium containing ManMA, after which a sufficient amount of PEG(4)10K-SH is in contact with the cells in the presence of a photoinitiator. The cells are then exposed to UV-light for 10 min. The immobilization of PEG(4)10K-SH, termed PEGylation, on the cell surface is confirmed by fluorescence microscopy. The surface modification does not influence cell viability. Biotinylation of cell surface can also be achieved by the addition of a vinyl compound during PEGylation. By using this process, the functionalities of a cell surface can be freely controlled.