Investigating polymer thiolation in gene delivery

Abstract

Thiolated polymers containing disulfide linkages are commonly researched in gene delivery with the assumption that the thiolated complexes form disulfide bonds. This study investigates the extent of disulfide linking in a thiol-containing polymer and determines the impact that free thiols have on the polymer's delivery potential. A fluorescent cationic polymer containing thiol pendant chains was prepared from poly(allylamine) and 2-iminothiolate (Traut's reagent). Polymer fluorescence was determined by UV plate readings and fluorescent microscopy. Transfection efficiency and cytotoxicity were assessed in MCF-7 breast cancer cells. Results show that thiolated polymers exhibited fluorescence at ex/em ∼595/620. Fluorescent measurements, microscopy imaging, and DNA electrophoresis show that thiolated polymers are not internalized by cells in a culture, yet, they bind to the cell surface, perhaps valuable for applications requiring cell adhesion.