A Heterogeneous PNA-Based SERS Method for DNA Detection

Abstract

A simple method for ssDNA detection based on SERS signals and PNA slides is reported. Upon hybridization with ssDNA, the surface charge of the PNA slides changes from neutral to negative. Subsequent treatment with partly aggregated, positively charged silver nanoparticles results in selective electrostatic adsorption onto surfaces containing PNA/ssDNA duplexes. Addition of rhodamine6G gives rise to SERS signals characteristic of this dye, which are diagnostic of the hybridization event. Characterization by SERS maps and AFM reveals that the distribution of nanoparticles is random and that approximately 1 in 10 aggregate sites is responsible for the SERS spectra.

Integrated nanostructures for direct detection of DNA at attomolar concentrations

“…In this approach, electrochemical current is generated by reduction of positively charged Ru͑NH 3 ͒ 6 3+ , a DNA-binding electron acceptor. The electrical current is further amplified by introducing Fe͑CN͒ 6 3− that serves as an anionic electron acceptor. The result is an electrocatalytic reporter system for high-gain hybridization-event signal transduction.…”

A Novel Type of Nucleic Acid-based Biosensors: the Use of PNA Probes, Associated with Surface Science and Electrochemical Detection Techniques

“…Detection of DNA by SERS may also take advantage of the electrostatic interactions generated when the oligonucleotides interacts with PNA; this enables the binding of positively charged nanoparticles bearing a SERS reporter molecule for instance. In Fabris et al study (Fabris et al, 2007), DNA was hybridised to PNA immobilised on slides, leaving a negatively-charged surface; immersion in a solution of positively-charged Ag Nanoparticles (NPs), and then in a solution of rhodamine SERS reporters, leads to intense SERS signal, attributed to the specific PNA-DNA interaction. Note that addition of non-complementary ssDNA, at the initial step, leaves the PNA layer unmodified, thus not binding nanoparticles; a resulting none or quasi no SERS signal has been observed (see Fig.…”

“…General scheme of the assay, PNA in green and complementary DNA in blue. SERS signals from PNA slides hybridised with ssDNAc (blue) or ssDNAnc (red) (Fabris et al, 2007). could be detected by SERS (Fang et al, 2008a), with a detection limit of 1x10 -12 M. Of course, the sensitivity increases with the oligonucleotide length due to the higher amount of phosphate groups.…”

Peptide Nucleic Acid – An Opportunity for Bio-Nanotechnology

“…[22] PNAs have already been used in this context. [23][24][25] For example, Bazan and coworkers have developed a SERS sensor for singlestranded DNA (Fig. 5).…”