Correlation of molecular orientation and packing density in a dsDNA self-assembled monolayer observable with surface-enhanced Raman spectroscopy.
Observations of two spectrally distinct ring breathing modes of guanine and adenine in the surface-enhanced Raman spectrum (SERS) of a dsDNA self-assembled monolayer on an Au nanoshell SERS substrate provide information concerning the orientation of its constituent molecules. The two modes vary with DNA concentration in a highly systematic manner, consistent with studies suggesting DNA molecules tend toward a more horizontal orientation at low-surface concentrations and a more vertical conformation at high concentrations. The introduction of small molecular spacers coadsorbed onto the Au nanoshell surface to "raise" the DNA molecules yields a SERS spectrum consistent with a more upright molecular orientation.
Department of Chemistry, Rice University, Houston, Texas 77005, USA.
Aoune
A
Barhoumi
Dongmao
D
Zhang
Naomi J
NJ
Halas
D000225:Adenine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012015:Reference Standards; D013059:Spectrum Analysis, Raman / Q000379:methods* / Q000592:standards; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
D013438:Sulfhydryl Compounds; D006147:Guanine; D006046:Gold; D004247:DNA; D000225:Adenine