Polythiol-anchored DNA monolayers for biosensing applications

Recent technological advances have seen the development of various platforms for detecting biomolecular interactions. An important aspect of the modification of solid supports with biological polymers is to anchor the molecule of interest permanently and in well-defined attachment geometry. Gold is the most common metal support for research applications but suffers from a lack of methods for producing robust biomolecular films that can withstand prolonged use, especially at elevated temperatures. This paper reports on the development of a novel attachment scheme for immobilizing biomolecules to metal supports. Poly(mercaptopropyl)methylsiloxane (PMPMS) films chemisorbed on gold provide thermally stable, nanometer-thin, thiol-rich anchor layers suitable for subsequent attachment of biomolecules. The exceptional stability of PMPMS-anchored single stranded DNA monolayers is anticipated to benefit applications in biomolecular diagnostics, as well as assist in fundamental investigations of biomacromolecules at interfaces. In an attempt to exploit PMPMS films in impedance-based biodiagnostics, initial studies have shown that immobilization of DNA to the PMPMS modified Au surfaces lowers the interfacial capacitance. Preliminary results on hybridization of target DNA to the probe modified surfaces show that impedance changes can be measured.