Carbon-on-Metal Films for Surface Plasmon Resonance Detection of DNA Arrays

摘要

Surface plasmon resonance (SPR) measurements provide a highly sensitive means for detecting biomolecular interactions in a label-free manner. Numerous studies of biomolecular interactions have been performed with fixed-angle SPR imaging (SPRi) on surfaces patterned with a variety of biomolecules such as DNA, RNA, proteins, and peptides. Arrays increase the information obtainable in a single experiment as multiple reactions can be monitored in parallel. A current and significant limitation of SPR is that the substrate must be a metal thin film. A number of metal thin films are capable of supporting surface plasmons in the near-infrared and visible regions of the electromagnetic spectrum. Gold surfaces have been the substrate of choice for SPR measurements for two reasons: gold is relatively stable in the aqueous environments needed for monitoring biomolecular interactions and a versatile chemistry based on the attachment of sulfur-containing ligands to the gold surface has been developed and well-characterized. The readily formed gold-sulfur bond enables the direct attachment of ligands to the gold surface as well as attachment via an intermediate self-assembled monolayer (SAM).This gold-thiol chemistry has made possible the routine analysis of aqueous binding processes to immobilized molecules at near-neutral pH values and moderate temperatures. The susceptibility of the gold-sulfur bond to oxidation and photodecomposition has prevented SPR sensing from finding utility in areas such as on-surface combinatorial chemistry (due to the harsh chemical conditions employed) and photolithography (due to the adverse effects of ultraviolet radiation on the gold-sulfur bond).