Investigating the Morphology and Mechanics of Biogenic Hierarchical Materials at and below Micrometer Scale.

Investigating and understanding the intrinsic material properties of biogenic materials, which have evolved over millions of years into admirable structures with difficult to mimic hierarchical levels, holds the potential of replacing trial-and-error-based materials optimization in our efforts to make synthetic materials of similarly advanced complexity and properties. An excellent example is biogenic silica which is found in the exoskeleton of unicellular photosynthetic algae termed diatoms. Because of the complex micro- and nanostructures found in their exoskeleton, determining the intrinsic mechanical properties of biosilica in diatoms has only partly been accomplished.

Chain length of bioinspired polyamines affects size and condensation of monodisperse silica particles.

Polyamines play a major role in biosilicification reactions in diatoms and sponges. While the effects of polyamines on silicic acid oligomerization and precipitation are well known, the impact of polyamines chain length on silica particle growth is unclear. We studied the effects of polyamine chain length on silica particle growth and condensation in a known, simple, and salt-free biphasic reaction system; with tetraethyl orthosilicate as organic phase and polyamine dissolved in the aqueous phase.

Studying Reaction Mechanisms in Solution Using a Distributed Electron Microscopy Method.

Electron microscopy (EM) of materials undergoing chemical reactions provides knowledge of the underlying mechanisms. However, the mechanisms are often complex and cannot be fully resolved using a single method. Here, we present a distributed electron microscopy method for studying complex reactions.

Modifying the thickness, pore size, and composition of diatom frustule in Pinnularia sp. with Al ions.

Diatoms are unicellular photosynthetic algae that produce a silica exoskeleton (frustule) which exposes a highly ordered nano to micro scale morphology. In recent years there has been a growing interest in modifying diatom frustules for technological applications. This is achieved by adding non-essential metals to the growth medium of diatoms which in turn modifies morphology, composition, and resulting properties of the frustule.

Flexibility of components alters the self-assembly pathway of PdL coordination cages.

The self-assembly process of a PdL cage consisting of flexible ditopic ligands and Pd(ii) ions was revealed by QASAP (quantitative analysis of self-assembly process), which enables one to obtain information about the intermediates transiently produced during the self-assembly as the average composition of all the intermediates. It was found that the dominant pathway to the cage is the formation of a submicrometre-sized sheet structure, which was characterized by dynamic light scattering (DLS) and scanning transmission electron microscopy (STEM), followed by the addition of free ditopic ligands to the Pd(ii) centres of the sheet structure to trigger the cage formation. This assembly process is completely different from that of a PdL cage composed of rigid ditopic ligands, indicating that the flexibility of the components strongly affects the self-assembly process.

Heterogeneous catalase-like activity of gold(i)-cobalt(iii) metallosupramolecular ionic crystals.

Unique heterogeneous catalase-like activity was observed for metallosupramolecular ionic crystals [AuCo(dppe)(d-pen)]X ([]X ; dppe = 1,2-bis(diphenylphosphino)ethane; d-pen = d-penicillaminate; X = (Cl), (ClO), (NO) or SO) consisting of AuCo complex cations, [], and inorganic anions, X or X. Treatment of the ionic crystals with an aqueous HO solution led to considerable O evolution with a high turnover frequency of 1.4 × 10 h for the heterogeneous cobalt complexes, which was dependent on their size and shape as well as the arrangement of cationic and anionic species.

Intracellular delivery of BSA by phosphonate@silica nanoparticles.

Intracellular protein (BSA) delivery by a phosphonate@mesoporous silica nanoparticle vehicle, PMSN, with high load capacity for the relatively large test protein BSA, is described. Wide pore (11.6 nm) PMSN nanoparticles were synthesised and loaded with a BSA cargo to give BSA@PMSN*, where # and * signify Fluorescein and Rhodamine fluorescent labels respectively.

Large pore raspberry textured phosphonate@silica nanoparticles for protein immobilization.

This paper reports the synthesis of large pore (11 nm) monodisperse raspberry textured phosphonate@silica nanoparticles (70-90 nm) with high capacity for protein immobilization. The raspberry nanoparticles denoted RNP_PME(2.5) with phosphonate loading 2.