DNA interaction probed by evanescent wave cavity ring-down absorption spectroscopy via functionalized gold nanoparticles

• Interaction of DNA strands by using gold nanoparticles as reporters have studied.
• Evanescent-wave cavity ring-down absorption spectroscopy is used for study.
• Direct DNA hybridization and sandwich hybridization assay are characterized.
• A target DNA is monitored to obtain detection limit and equilibrium constants.
• Sickle-cell anemia is detected for detection limit and equilibrium constant.

Evanescent wave cavity ring-down absorption spectroscopy (EW-CRDS) is employed to study interaction and binding kinetics of DNA strands by using gold nanoparticles (Au NPs) as sensitive reporters. These Au NPs are connected to target DNA of study that hybridizes with the complementary DNA fixed on the silica surface. By the absorbance of Au NPs, the interaction between two DNA strands may be examined to yield an adsorption equilibrium constant of 2.2 × 1010 M−1 using Langmuir fit. The binding efficiency that is affected by ion concentration, buffer pH and temperature is also examined. This approach is then applied to the label-free detection of the DNA mutation diseases using the sandwich hybridization assay. For monitoring a gene associated with sickle-cell anemia, the detection limit and the adsorption equilibrium constant is determined to be 1.2 pM and (3.7 ± 0.8) × 1010 M−1, distinct difference from the perfectly matched DNA sequence that yields the corresponding 0.5 pM and (1.1 ± 0.2) × 1011 M−1. The EW-CRDS method appears to have great potential for the investigation of the kinetics of a wide range of biological reactions.

(a) Direct DNA hybridization and (b) sandwich hybridization assay.Figure optionsDownload as PowerPoint slide