The pH-dependent elastic properties of nanoscale DNA films and the resultant bending signals for microcantilever biosensors

A schematic of the nanoscopic structure of the DNA film (with 16 nucleotides per chain) and the related motion of the microcantilever in a PBS buffer solution (137 mM NaCl, 2.7 mM KCl, 8 mM Na2HPO4, and 2 mM KH2PO4; pH = 7.5).

Continuous rearrangement of the postsynaptic gephyrin scaffolding domain: a super-resolution quantified and energetic approach

Synaptic function and plasticity requires a delicate balance between overall structural stability and the continuous rearrangement of the components that make up the presynaptic active zone and the postsynaptic density (PSD). Photoactivated localization microscopy (PALM) has provided a detailed view of the nanoscopic structure and organization of some of these synaptic elements. Still lacking, are tools to address the morphing and stability of such complexes at super-resolution. We describe an approach to quantify morphological changes and energetic states of multimolecular assemblies over time. With this method, we studied the scaffold protein gephyrin, which forms postsynaptic clusters that play a key role in the stabilization of receptors at inhibitory synapses. Postsynaptic gephyrin clusters exhibit an internal microstructure composed of nanodomains. We found, that within the PSD, gephyrin molecules continuously undergo spatial reorganization. This dynamic behavior depends on neuronal activity and cytoskeleton integrity. The proposed approach also allowed access to the effective energy responsible for the tenacity of the PSD despite molecular instability.Significant statementSuper-resolution microscopy has become an important tool for the study of biological systems, allowing detailed, nano-scale structural reconstruction, single molecule tracking, particle counting, and interaction studies. However, quantification tools that take full advantage of the information provided by this technology are still lacking. We describe a novel quantification method to obtain information related to the size, directionality, dynamics, and stability of clustered structures from super-resolution microscopy. With this method, we studied the stability of gephyrin clusters, the main inhibitory scaffold protein. We found that gephyrin molecules continuously undergo reorganization based on neuronal activity and changes in the cytoskeleton.

Unraveling the sub-nanoscopic structure at interphase in a poly(vinyl alcohol)–MOF nanocomposite, and its role in thermo-mechanical properties

Polymer chain framework at the interfacial region in PVA–MOF nanocomposites can be represented by a rigid but rather open network.

Molecular dynamics simulation of amino acid ionic liquids near a graphene electrode: effects of alkyl side-chain length

The nanoscopic structure of amino acid ionic liquids (AAILs) as biodegradable electrolytes near a neutral graphene surface was studied by molecular dynamics (MD) simulation.

New Organic-Inorganic Hybrid Ureasil-Based Polymer Materials Studied by PALS and SEM Techniques

The new organic-inorganic materials, based on polyether chains covalently linked to a silica framework through urea bridges, referred as ureasilicates or ureasils, and semiconducting As2S3-ureasil composites are investigated using positron annihilation lifetime spectroscopy (PALS) and scanning electron microscopy (SEM) techniques. The results obtained show that incorporation of the As2S3 clusters into ureasil affects on the ortho-positronium (o-Ps) intensity or positronium formation probability and micro-/nanoscopic structure compared to the pure polymer, the effect is more essential as the loading fraction of As2S3 increases.