Photopatterned Thiol Surfaces for Biomolecule Immobilization

Abstract

The ability to pattern small molecules and proteins on artificial surfaces is of importance for the development of new tools including tissue engineering, cell-based drug screening, and cell-based sensors. We describe here a novel "caged" thiol-mediated strategy for the fabrication of planar substrates patterned with biomolecules using photolithography. A thiol-bearing phosphoramidite (3-(2'-nitrobenzyl)thiopropyl (NBTP) phosphoramidite) was synthesized and coupled to a hydroxyl-terminated amorphous carbon substrate. A biocompatible oligo(ethylene glycol) spacer was used to resist nonspecific adsorption of protein and DNA and enhance flexibility of attached biomolecules. Thiol functionalities are revealed by UV irradiation of NBTP-modified surfaces. Both the surface coupling and photodeprotection were monitored by Polarization Modulation Fourier Transform Infrared Reflection Absorption Spectroscopy (PM-FTIRRAS) and X-ray Photoelectron Spectroscopy (XPS) measurements. The newly exposed thiols are chemically very active and react readily with a wide variety of groups. A series of molecules including biotin, DNA, and proteins were attached to the surfaces with retention of their biological activities, demonstrating the utility and generality of the approach.