We have synthesized inorganic micron-sized filaments, whose microstucture consists of silica-coated nanometer-sized carbonate crystals, arranged with strong orientational order. They exhibit noncrystallographic, curved, helical morphologies, reminiscent of biological forms. The filaments are similar to supposed cyanobacterial microfossils from the Precambrian Warrawoona chert formation in Western Australia, reputed to be the oldest terrestrial microfossils. Simple organic hydrocarbons, whose sources may also be abiotic and indeed inorganic, readily condense onto these filaments and subsequently polymerize under gentle heating to yield kerogenous products. Our results demonstrate that abiotic and morphologically complex microstructures that are identical to currently accepted biogenic materials can be synthesized inorganically.

This paper deals with the difficulty of decoding the origins of natural structures through the study of their morphological features. We focus on the case of primitive life detection, where it is clear that the principles of comparative anatomy cannot be applied. A range of inorganic processes are described that result in morphologies emulating biological shapes, with particular emphasis on geochemically plausible processes. In particular, the formation of inorganic biomorphs in alkaline silica-rich environments are described in detail.

The morphology of the aggregates formed between DNA and poly(amido amine) (PAMAM) dendrimers depends on the dendrimer generation as previously reported in separate studies at high dendrimer/DNA charge ratios (>1). This has lead to substantial work on dendrimers as possible transfection agents. Inspired by these studies, we here present novel results from a coherent and systematic study using cryo-TEM, dynamic light scattering (DLS) and fluorescence spectroscopy to reveal how the size, composition and morphology of aggregates formed between DNA (4331 base pairs) and PAMAM dendrimers, are affected by dendrimer size and charge at low charge ratios (<1) in dilute solutions. At such conditions the process is cooperative and kinetically controlled and welldefined structured aggregates are formed for lower dendrimer generations. The smaller sized dendrimers (generation 1 and 2), which have a lower total charge per molecule, allow the formation of well-structured rods and toroids. In contrast, globular and less defined aggregates, which are less stable against precipitation, are formed with higher generation dendrimers. We were also able to directly visualise the cooperative nature of the condensation process as cryo-TEM and DLS show that dendrimer/DNA aggregates, containing condensed DNA, coexist with free extended DNA chains. In fact, the apparent hydrodynamic radii of the dendrimer/DNA aggregates, obtained using DLS, are found to be almost constant for charge ratios #1. The fluorescence study shows that the number of dendrimers bound per DNA chain decreases with the dendrimer generation but is independent of the charge ratio.

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We describe self-assembled silica-carbonate aggregates that show a diverse range of morphologies, all of which display complex internal structure, orientational ordering of components, and well-organised, curved global morphologies that bear a strong resemblance to biogenic forms. The internal order is described as a liquid-crystallike organisation of colloidal particles. We discuss possible causes for the striking morphologies of these inorganic materials, including local nanocrystal packing constraints and global silica membrane templating.

Here, monoolein-based nanoparticles (NPs), obtained through fragmentation of bulk liquid crystalline phases, and stabilized by two different emulsifiers, namely, Pluronic F127 (PF127) and lauroylcholine chloride (LCh), are investigated for structural features and for short-term in vitro cytotoxicity. Depending on the emulsifiers, different morphologies of the lipid NPs (cubosomes and liposomes) are obtained, as demonstrated by cryo-TEM images. Although NPs offer many advantages in medical applications and various chemicals used for their preparation are under investigation, so far there are no standardized procedures to evaluate cell biocompatibility. Two different protocols to evaluate the impact of these lipid NPs on biological systems are presented. Results show that nanoparticles stabilized by PF127 (cubosomes) display a relevant toxicity toward different cell lines, whereas those stabilized by LCh (liposomes) affect cell viability at a much lesser extent.

The aggregation of the amyloid β peptide (Aβ) into amyloid fibrils is a defining characteristic of Alzheimer's disease. Because of the complexity of this aggregation process, effective therapeutic inhibitors will need to target the specific microscopic steps that lead to the production of neurotoxic species. We introduce a strategy for generating fibril-specific antibodies that selectively suppress fibril-dependent secondary nucleation of the 42-residue form of Aβ (Aβ42). We target this step because it has been shown to produce the majority of neurotoxic species during aggregation of Aβ42. Starting from large phage display libraries of single-chain antibody fragments (scFvs), the three-stage approach that we describe includes (i) selection of scFvs with high affinity for Aβ42 fibrils after removal of scFvs that bind Aβ42 in its monomeric form; (ii) ranking, by surface plasmon resonance affinity measurements, of the resulting candidate scFvs that bind to the Aβ42 fibrils; and (iii) kinetic screening and analysis to find the scFvs that inhibit selectively the fibril-catalyzed secondary nucleation process in Aβ42 aggregation. By applying this approach, we have identified four scFvs that inhibit specifically the fibril-dependent secondary nucleation process. Our method also makes it possible to discard antibodies that inhibit elongation, an important factor because the suppression of elongation does not target directly the production of toxic oligomers and may even lead to its increase. On the basis of our results, we suggest that the method described here could form the basis for rationally designed immunotherapy strategies to combat Alzheimer's and related neurodegenerative diseases.Alzheimer | antibody | inhibitor | drug development | self-assembly

We explore the use of tetraethoxysilane (TEOS) as a silica source for the formation of carbonate-silica composite materials known as 'biomorphs'. The basic hydrolysis of TEOS furnishes silica in a controllable fashion, allowing a significantly higher reproducibility of the obtained silica-barium and silica-strontium carbonate co-precipitates compared to commercial water glass silica used so far. We further discuss the influence of ethanol used as a co-solvent on the morphologies of biomorphs, which are examined by optical microscopy, field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX).