7 research outputs found
Local structure of Liquid-Vapour Interfaces
The structure of a simple liquid may be characterised in terms of ground
state clusters of small numbers of atoms of that same liquid. Here we use this
sensitive structural probe to consider the effect of a liquid-vapour interface
upon the liquid structure. At higher temperatures (above around half the
critical temperature) we find that the predominant effect of the interface is
to reduce the local density, which significantly suppresses the local cluster
populations. At lower temperatures, however, pronounced interfacial layering is
found. This appears to be connected with significant orientational ordering of
clusters based on 3- and 5-membered rings, with the rings aligning
perpendicular and parallel to the interface respectively. At all temperatures,
we find that the population of five-fold symmetric structures is suppressed,
rather than enhanced, close to the interface.Comment: 10 pages, 8 figures, accepted for publication by Molecular Physic
A DNA aptamer recognising a malaria protein biomarker can function as part of a DNA origami assembly
DNA aptamers have potential for disease diagnosis and as therapeutics, particularly when interfaced with programmable molecular technology. Here we have combined DNA aptamers specific for the malaria biomarker Plasmodium falciparum lactate dehydrogenase (PfLDH) with a DNA origami scaffold. Twelve aptamers that recognise PfLDH were integrated into a rectangular DNA origami and atomic force microscopy demonstrated that the incorporated aptamers preserve their ability to specifically bind target protein. Captured PfLDH retained enzymatic activity and protein-aptamer binding was observed dynamically using high-speed AFM. This work demonstrates the ability of DNA aptamers to recognise a malaria biomarker whilst being integrated within a supramolecular DNA scaffold, opening new possibilities for malaria diagnostic approaches based on DNA nanotechnology
Effect of PEGylation on Controllably Spaced Adsorption of Ferritin Molecules
The
interparticle distance between nanoparticles (NPs) dispersed
on on SiO<sub>2</sub> was shown to be controlled by PEGylation. Ferritins
with nanoparticle cores were prepared and PEGylated with poly(ethylene
glycol)s (PEGs) of two different molecular weights. It was shown that
the thickness of the PEG layer on the ferritin surface determines
the interparticle distance under short Debye lengths. Under conditions
where the Debye length was greater than the PEG layer thickness, distance
between ferritins increased due to the electrostatic repulsive force.
Results suggest that the PEG layer accommodated a small amount of
counterions insufficient to cancel the ferritin outer surface charges.
Simulation showed that ferritins adsorbed randomly and interparticle
distance can be predicted theoretically. We demonstrate that PEGylated
ferritins, that is, NP cores, can be dispersed on a surface with interval
distances between particles determined by the combination of the ionic
strength of the solution and the molecular weight of the PEG