Attenuated total reflectance Fourier transform infrared spectroscopy was used to detect DNA hybridization on a polystyrene conjugated gold nanoparticle thin film. The gold nanoparticles were synthesized on the surface of poly(ethylenimine) coated polystyrene particles by citrate reduction. Single-stranded DNA was then immobilized on the nanoparticle surface via thiol bonding. Ultraviolet-visible spectrometry was used to monitor the conjugation of the nanoparticles on polystyrene particles and the immobilization of a single-stranded DNA probe. The morphology of the polystyrene-gold nanoparticle thin film was characterized using scanning electron microscopy and showed successful conjugation and immobilization. The infrared spectra obtained from the hybridization showed features of DNA structure and peak shifts at 1657 cm-1 compared to the non-complementary DNA due to changes in hydrogen bonding between N-H and C=O of complimentary bases pairs. The peaks at 1067, 975, 920, and 859 cm-1, which were shifted to lower wavenumbers in the polystyrene-gold nanoparticle probe and target DNA, indicated hydrogen bonding formation between N-H and N of complimentary base pairs. ATR-FTIR spectroscopy provided simple, fast, and portable label-free detection of target DNA sequence on the polystyrene-gold nanoparticle thin film.
Bibliographical noteFunding Information:
Received 24 May 2013; accepted 2 July 2013. J. Otano and M.-P. N. Bui contributed equally. This work was supported by grants from the Department of Defense, Grant # W911NF-11-1-0181, DOD CDMRP Training Grant: Grant # W81XWH-10-1-1042 and the undergraduate research program at Albany State University whose support is greatly appreciated. Address correspondence to Dr. Seong S. Seo, Department of Natural Science, Albany State University, Albany, GA 31705, USA. E-mail: email@example.com
- DNA hybridization
- Gold nanoparticle
- Thin film