Synthesis and characterization of a photoactivatable glycoaryldiazirine for surface glycoengineering

Biological systems make considerable use of specific molecular interactions . Many biomolecules involved in biorecognition are glycosylated, the carboh ydrate moiety playing an essential role. Controlled surface glycoengineerin g is thus of crucial importance in biosensing, cell guidance, and biomedica l applications. This study describes the synthesis of an aryldiazirine-deri vatized galactose and the functionalization of surfaces by carbohydrates us ing photochemical immobilization techniques. A photoactivatable glycosylate d reagent was synthesized by addition of thiogalactopyranose to the maleimi de group of N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl]-4-maleimidobutyr amide (MAD) to give N-[m-[3-(trifluoromethyl) diazirin-3-yl]phenyl]-4-[3-th io(1-D-galactopyranosyl)succinimidyl]butyramide (MAD-Gal). The structure of the newly synthesized molecule was confirmed by UV spectroscopy, photoacti vation, H-1 NMR, and C-13 NMR. MAD-Gal was immobilized on thin diamond film s by photoactivation of the diazirine function (350 nm). Surface modificati on was investigated by XPS (X-ray photoelectron spectroscopy) and ToF-SIMS (time-of-flight secondary ion mass spectrometry). Imaging ToF-SIMS was appl ied to detect glycopatterns generated by mask-assisted lithography.