Gold nanoparticle aggregation-based highly sensitive DNA detection using atomic force microscopy

Abstract

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.

Preparation of mecA Biosensor Based On Gold Nanoparticles to Determine Methicillin Resistant Staphylococcus Aureus (MRSA) Strains from Human and Animals

“…Amounts of target DNA were 1, 2.5, 7.5 and 10 µl per total volume which was 200 µl. Positive results were agree with (Bui et al, 2007) as the positive results were showed as shifting of color of conjugated GNPs from pink to purples in which indicated aggregation of particles and formation of polymeric network causing decreasing of inter-particles distance. Such physical explanation was done by (Elghanian, 1997)and (Radwan and Azzazy, 2009) who also mentioned that hybridization of the GNPs-labeled probe to the target caused aggregation and a change of the solution form pinky red to purple blue.…”

A direct detection of Escherichia coli genomic DNA using gold nanoprobes

“…High resolution images of nanoparticles by AFM have been successfully used in the past to study of DNA- nanoparticle interactions [23,37,38,41]. To elucidate the nature of AuNP- oligo probe and target DNA interaction in our test samples, AFM images of these complexes are taken.…”

“…Considerable work was carried out that explore the basic properties of gold nanoparticles [15-17]. DNA-functionalized AuNPs are used in a variety of molecular diagnostic applications such as high sensitivity DNA detection in homogenous solution [18] and microarray- based DNA detection [19], lab-on-chip based substrates [20-22], atomic force microscopy based detection [23], detection of polymerase chain reaction (PCR) amplicons [24,25]. The optical property of colloidal AuNPs forms the basis of its application in rapid and specific hybridization based DNA detections.…”

A smart nanofibrous material for adsorbing and detecting elemental mercury in air

“…The color strictly depends on the size of the nanoparticles and then their agglomeration at the solid state. According to Bui et al (2007), such a band-broadening phenomenon is due to the electric dipoledipole interactions and coupling occurring between the plasmons of neighboring particles, whereas nanoparticle agglomeration phenomena occurred.…”