Synthesis of a pyridyl disulfide end-functionalized glycopolymer for conjugation to biomolecules and patterning on gold surfaces

A pyridyl disulfide end-functionalized polymer with N-acetyl-D-glucosamine pendant side-chains was synthesized by atom transfer radical polymerization (ATRP). The glycopolymer was prepared from a pyridyl disulfide initiator catalyzed by a Cu(I)/Cu(II)/2,2′-bipyridine system in a mixture of methanol and water at 30°C. The final polymer had a number-average molecular weight (M_n) of 13.0 kDa determined by ¹H NMR spectroscopy and a narrow polydispersity index (1.12) determined by gel permeation chromatography (GPC). The pyridyl disulfide endgroup was then utilized to conjugate the glycopolymer to a double-stranded short interfering RNA (siRNA). Characterization of the glycopolymer-siRNA by polyacrylamide gel electrophoresis (PAGE) showed 97% conjugation. The activated disulfide polymer was also patterned on gold via microcontact printing. The pyridyl disulfide allowed for ready immobilization of the glycopolymer into 200 μm sized features on the surface.