Size-Controlled Nanoparticle Clusters of Narrow Size-Polydispersity Formed Using Multiple Particle Types Through Competitive Stabilizer Desorption to a Liquid-Liquid Interface

A novel colloidal approach is presented for preparing fully dispersed nanoparticle (NP) assemblies (clusters) of narrow size-polydispersity over a wide range of sizes through irreversible depletion of stabilizing ligands onto a liquid-liquid interface. Unusually, the relative monodispersity of the assemblies continuously improves throughout the process. A detailed kinetics study into the assembly of iron oxide NP clusters shows that the assembly rate decreases with NP concentration, pinpointing the role of the interface in size focusing. A new protocol for identifying initial conditions that enable controlled assembly is described, which allows extension of the approach to multiple NP types, opening up a general route to colloidally processed materials. The process uses cheap materials, it is reproducible, robust, and scaleable, and it allows for selection of both particle and cluster size. In the case of assemblies of magnetic iron oxide NPs, these advantages enable tuning of the magnetic properties of the assemblies for applications such as magnetically targetable MRI-trackable agents in biomedicine.

Inclusion of silver nanoparticles for improving regenerated cellulose membrane performance and reduction of biofouling

The preparation of silver nanoparticles (AgNPs) and their incorporation into the structure of a regenerated cellulose membrane by dip coating is presented. Morphological characterization of the AgNPs (average diameter of 20±2nm) was carried out by SEM/TEM, while elastic, electrical and antimicrobial properties of the hybrid membrane were also analyzed. The presence of silver nanoparticles in the membrane seems to increases its rigidity and its chemical stability against oxidation, but it only induces small changes in the transport parameters. As expected, AgNPs provide antimicrobial properties to the membrane and consequently the reduction of biofouling without affecting significantly other characteristic parameters, opening the application of the modified membrane to wastewaters treatment.

Comparative Genomics Within the Bacillus Genus Reveal the Singularities of Two Robust Bacillus amyloliquefaciens Biocontrol Strains

Bacillus amyloliquefaciens CECT 8237 and CECT 8238, formerly known as Bacillus subtilis UMAF6639 and UMAF6614, respectively, contribute to plant health by facing microbial pathogens or inducing the plant's defense mechanisms. We sequenced their genomes and developed a set of ad hoc scripts that allowed us to search for the features implicated in their beneficial interaction with plants. We define a core set of genes that should ideally be found in any beneficial Bacillus strain, including the production of secondary metabolites, volatile compounds, metabolic plasticity, cell-to-cell communication systems, and biofilm formation. We experimentally prove that some of these genetic elements are active, such as i) the production of known secondary metabolites or ii) acetoin and 2-3-butanediol, compounds that stimulate plant growth and host defense responses. A comparison with other Bacillus genomes permits us to find differences in the cell-to-cell communication system and biofilm formation and to hypothesize variations in their persistence and resistance ability in diverse environmental conditions. In addition, the major protection provided by CECT 8237 and CECT 8238, which is different from other Bacillus strains against bacterial and fungal melon diseases, permits us to propose a correlation with their singular genetic background and determine the need to search for additional blind biocontrol-related features.

Monodisperse magnetic nanoparticle assemblies prepared at scale by competitive stabiliser desorption

We report a scalable and reproducible method to assemble magnetic nanoparticle clusters from oleic acid stabilised iron oxide nanoparticles.