Advanced CryoTEM and tomography for two- And three-dimensional nano-characterisation of soft matter

\u3cp\u3eRecent advances in transmission electron microscopy (TEM) have led to unprecedented automated control over data acquisition for various applications. Improvement of methods for obtaining and reconstructing tilt series projections allow us to create three-dimensional tomographic representations of bulk materials at the nanoscale. We demonstrate the combination of the latest TEM technology and tomography, at cryogenic temperatures, for the observation of soft matter such as polymers, hybrid coatings, engineered proteins and nanoparticles for targeted gene and drug delivery, nanocomposites and biomaterials, in conjunction with stateof-the-art vitrification methods for specimen preparation. Using such advanced Cryo-TEM, we aim to understand the organization of molecules, macromolecules and biomolecules, in order to control the properties and performance of materials and devices.\u3c/p\u3

Assembly strategies for enzyme immobilization

No abstract

Stepwise noncovalent synthesis leading to dendrimer-based assemblies in water

We provide detailed insight into complex supramolecular assembly processes by fully characterizing a multicomponent model system using dynamic light scattering, cryogenic transmission electron microscopy, atomic force microscopy, and various NMR techniques. First, a preassembly of a host molecule (the fifth-generation urea-adamantyl poly(propylene imine) dendrimer) and 32 guest molecules (a water- and chloroform-soluble ureidoacetic acid guest) was made in chloroform. The association constant in chloroform is concealed by guest self-association and is therefore higher than 103 M-1. Via the neat state the single-host complex was transferred to water, where larger dendrimer-based assemblies were formed. The core of these assemblies, consisting of multiple host molecules (on average three), is kinetically trapped upon dissolution in water, and its size is constant irrespective of the concentration. The guest molecules forming the corona of the assemblies, however, stay dynamic since they are still in rapid exchange on the NMR time scale, as they were in chloroform. A stepwise noncovalent synthesis provides a means to obtain metastable dynamic supramolecular assemblies in water, structures that cannot be formed in one step