Immobilisation of Multiple Ligands Using Peptide Nucleic Acids: A Strategy to Prepare the Microenvironment for Cell Culture

Cells often interact with various biomolecules simultaneously that are insoluble or immobilised form. We have developed a method to present multiple biological ligands on a solid support to emulate the physiological microenvironment. The immobilisation of biological ligands with precise spatial control was achieved using self-assembled monolayers (SAMs) of peptide nucleic acids (PNAs). Thiol-functionalised PNAs were patterned on a gold surface with the specific orientation using a microfluidic system. The complementary PNA sequences terminating with oxyamine groups were conjugated with aldehyde-or ketone-functionalised ligands via oxime ligation. The hybridisation of the ligand-carrying complementary PNA sequences onto the thiol-PNA on the gold surface resulted in the installation of functional ligands that can be used in manipulating cell behaviour. Adhesive ligands immobilised in this manner supported adhesion and growth of cells. Immobilisation of multiple ligands can be achieved through this method by designing different sequences of oligo PNAs without the necessity of complex orthogonal chemical coupling reactions.