Gold nanoparticle aggregation-based highly sensitive DNA detection using atomic force microscopy.
The potential ability of atomic force microscopy (AFM) as a quantitative bioanalysis tool is demonstrated by using gold nanoparticles as a size enhancer in a DNA hybridization reaction. Two sets of probe DNA were functionalized on gold nanoparticles and sandwich hybridization occurred between two probe DNAs and target DNA, resulting in aggregation of the nanoparticles. At high concentrations of target DNA in the range from 100 nM to 10 microM, the aggregation of gold nanoparticles was determined by monitoring the color change with UV-vis spectroscopy. The absorption spectra broadened after the exposure of DNA-gold nanoparticles to target DNA and a new absorption band at wavelengths >600 nm was observed. However, no differences were observed in the absorption spectra of the gold nanoparticles at low concentrations of target DNA (10 pM to 10 nM) due to insufficient aggregation. AFM was used as a biosensing tool over this range of target DNA concentrations in order to monitor the aggregation of gold nanoparticles and to quantify the concentration of target DNA. Based on the AFM images, we successfully evaluated particle number and size at low concentrations of target DNA. The calibration curve obtained when mean particle aggregate diameter was plotted against concentration of target DNA showed good linearity over the range 10 pM to 10 nM, the working range for quantitative target DNA analysis. This AFM-based DNA detection technique was three orders of magnitude more sensitive than a DNA detection method based on UV-vis spectroscopy.
Bui
Minh-Phuong Ngoc
MP
Department of Applied Chemistry, Hanyang University, Ansan, South Korea.
Baek
Taek Jin
TJ
Seong
Gi Hun
GH
D015374:Biosensing Techniques; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation / Q000379:methods*; D004247:DNA / Q000032:analysis* / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000295:instrumentation / Q000379:methods*; D008956:Models, Chemical; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D009693:Nucleic Acid Hybridization; D013056:Spectrophotometry, Ultraviolet; D013499:Surface Properties
D006046:Gold; D004247:DNA