Atomic force microscopy of oriented linear DNA molecules labeled with 5nm gold spheres

“…One of the concerns about drying the G-wires in this fashion is that the rinsing or receding meniscus might orient the G-wires due to hydrodynamic flow [5,6]. This clearly does not happen to the short G-wire DNA segments (average length 37 ± 18 nm, C = 68 ± 8%, Fig.…”

Section: Discussionmentioning

confidence: 99%

Auto-orientation of G-wire DNA on mica

Vesenka¹,

Bagg²,

Wolff³

et al. 2007

Colloids and Surfaces B: Biointerfaces

Self Cite

View full text Add to dashboard Cite

Scanning probe microscopy was used to examine the orientation of Tet1.5 quadruplex DNA polymers, a.k.a. "G-wires", after adsorption onto freshly cleaved Phyllosilicate micas. The G-wires appear to have a preferential orientation at 60• intervals after thorough rinsing and slow drying. The angles the G-wires made with the fast scan direction of the SPM probe were measured and the frequency-angle information was quantitatively characterized by an empirical correlation coefficient. Careful measurements indicate the Tet1.5 G-wires orient along the b lattice vector of mica, the next nearest neighbor potassium vacancy. A model is proposed to explain this auto-orientation affect due to alignment of the G-wires' phosphate backbone through magnesium tether cations. Pairs of adjacent, parallel phosphate groups of the G-wires (0.95 nm apart) appear to align with the next nearest neighbor potassium vacancy sites of mica (0.90 nm apart). This behavior is not observed in solution. The potential for using the auto-orientation phenomena in the development of high-density biomolecular nano-electronic devices is explored.

show abstract

“…Arguably, however, only over the past decade has the concept generated widespread excitement among chemists and materials scientists. Fueling the contemporary interest are demonstrated and emerging applications involving medical screening, 1 chemical sensing, 2 singleelectron conduction (Coulomb blockade behavior), 3 optical frequency tripling, 4 and new materials-assembly schemes. [5][6][7] Accompanying the new applications chemistry is a need for interface characterization.…”

mentioning

confidence: 99%

Enormous Hyper-Rayleigh Scattering from Nanocrystalline Gold Particle Suspensions

1998

View full text Add to dashboard Cite

The recent emergence of advanced technological applications for colloidal gold suspensions and related particle assemblies and interfaces has created a demand for new chemical and physical techniques with which to characterize them. For macroscopic samples/interfaces, coherent second harmonic generation (SHG) has proven itself a useful characterization tool due, at least in part, to metal-based plasmon enhancement. In an effort to defeat or bypass the size restrictions inherent to SHG, we have utilized a related incoherent methodology, hyper-Rayleigh scattering (HRS), to interrogate aqueous colloidal suspensions of 13 nm diameter gold particles. The nanoscale particles have proven to be remarkably efficient scatterers; when evaluated in terms of the first hyperpolarizability ( ), HRS signals from the gold particles substantially surpass those observable from the best available molecular chromophores. Moreover, the present experiments indicate that is highly sensitive to colloid aggregation and imply that HRS is an effective tool for the characterization of symmetry-reducing perturbations of nanoscale interfaces.The intentional miniaturization of metal/solution interfaces to the point where colloidal stabilization of suspensions of solvated metal particles occurs has been possible, at least at a rudimentary level, for more than a century. Arguably, however, only over the past decade has the concept generated widespread excitement among chemists and materials scientists. Fueling the contemporary interest are demonstrated and emerging applications involving medical screening, 1 chemical sensing, 2 singleelectron conduction (Coulomb blockade behavior), 3 optical frequency tripling, 4 and new materials-assembly schemes. [5][6][7] Accompanying the new applications chemistry is a need for interface characterization. Among the more attractive methodologies for macroscopic metal/solution interface characterization is optical second harmonic generation (SHG). 8 For otherwise centrosymmetric metal structures, interface formation creates an asymmetry providing for interface localized signal generation. SHG has been utilized to interrogate surface symmetry, 9,10 surface charge, 11 adsorbate coverage, 12 and/or adsorbate orientation 13 on gold surfaces as well as to interrogate gold particles at the liquid/air interface. 14 However, the coherent nature of conventional SHG and the necessity of utilizing a finite wavelength of radiation place a practical lower limit on sample size. 15 On the other hand, implementation of incoherent second harmonic generation or hyper-Rayleigh scattering (HRS) methods 16 should circumvent the interface size limitation (albeit at the expense of much smaller signal intensity). 17,18 On the basis of a successful application of HRS to nanoscale silica/water interfaces (surface acidity characterization) 19 and on the basis of a brief report of HRS from silver colloid samples (molecular adsorption effects), 20 we reasoned that the methodology might be applicable to nanoscale gold/water interfaces...

show abstract

Atomic force microscopy of oriented linear DNA molecules labeled with 5nm gold spheres

Cited by 70 publications

References 17 publications

Scanning tunneling microscopy study of a DNA fragment of known size and sequence

Scanning tunneling microscopy study of a DNA fragment of known size and sequence

Auto-orientation of G-wire DNA on mica

Enormous Hyper-Rayleigh Scattering from Nanocrystalline Gold Particle Suspensions

Contact Info

Product

Resources

About