Impact of nanosilver surface electronic distributions on serum protein interaction and hemocompatibility.

Translation of silver-based nanotechnology "from bench to bedside" requires a deep understanding of the molecular aspects of its biological action, which remains controversial at low concentrations and non-spherical morphologies. Here, we present a hemocompatibility approach based on the effect of the distinctive electronic charge distribution in silver nanoparticles (nanosilver) on blood components. On basis of spectroscopic, volumetric, microscopic, dynamic light scattering measurements, pro-coagulant activity tests and cellular inspection we determine that, at extremely low nanosilver concentrations (0.125 - 2.5 µg mL-1) there is a relevant interaction effect on serum albumin and on red blood cells. The explanation has its origin in the surface charge distribution of nanosilver and their electron-mediated energy transfer mechanism. Prism-shaped nanoparticles, with anisotropic charge distributions, act at the surface level generating a compaction of the native protein molecule, while the spherical nanosilver, by exhibiting isotropic surface charge, generates a polar environment comparable to the solvent. Both morphologies induce aggregation at NPs / BSA ≅ 0.044 molar ratio values without altering the coagulation cascade tests, although the spherical-shaped nanosilver has a negative impact on red blood cells. Overall, our results suggest that the electron distributions of nanosilver, even at extremely low concentrations, are a critical factor influencing the molecular structure of blood proteins and red blood cells' membranes. Isotropic forms of nanosilver should be considered with caution, as they are not always the least harmful.

NIR-responsive nano-holed titanium alloy surfaces: a photothermally activated antimicrobial biointerface.

Among external stimuli-responsive therapy approaches, those using near infrared (NIR) light irradiation have attracted significant attention to treat bone-related diseases and bone tissue regeneration. Therefore, the development of metallic biomaterials sensitive to NIR stimuli is an important area of research in orthopaedics. In this study, we have generated in situ prism-shaped silver nanoparticles (p-AgNPs) in a biomorphic nano-holed TiO2 coating on a Ti6Al4V alloy (a-Ti6Al4V). Insertion of p-AgNPs does not disturb the periodically arranged sub-wavelength-sized unit cell on the a-Ti6Al4V dielectric structure, while they exacerbate its peculiar optical response, which results in a higher NIR reflectivity and high efficiency of NIR photothermal energy conversion suitable to bacterial annihilation. Together, these results open a promising path toward strategic bone therapeutic procedures, providing novel insights into precision medicine.

MicroRNA miR394 regulates flowering time in Arabidopsis thaliana.

KEY MESSAGE: miR394 regulates Arabidopsis flowering time in a LCR-independent manner. Arabidopsis plants harboring mutations in theMIR394 genes exhibit early flowering, lower expression of floral repressor FLC and higher expression of floral integrators FT and SOC1. Plant development occurs throughout its entire life cycle and involves a phase transition between vegetative and reproductive phases, leading to the flowering process, fruit formation and ultimately seed production. It has been shown that the microRNA394 (miR394) regulates the accumulation of the transcript coding for LEAF CURLING RESPONSIVENESS, a member of a family of F-Box proteins. The miR394 pathway regulates several processes including leaf morphology and development of the shoot apical meristem during embryogenesis, as well as having been assigned a role in the response to biotic and abiotic stress in Arabidopsis thaliana and other species. Here, we characterized plants harboring mutations in MIR394 precursor genes and demonstrate that mir394a mir394b double mutants display an early flowering phenotype which correlates with a lower expression of FLOWERING LOCUS C earlier in development and higher expression of the floral integrators FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1. Consequently, mutant plants produce fewer branches and exhibit lower seed production. Our work reveals previously unknown developmental aspects regulated by the miR394 pathway, in an LCR-independent manner, contributing to the characterization of the multiple roles of this versatile plant regulatory miRNA.

NIR-Reflective and Hydrophobic Bio-Inspired Nano-Holed Configurations on Titanium Alloy.

Near-infrared (NIR) radiation plays an important role in guided external stimulus therapies; its application in bone-related treatments is becoming more and more frequent. Therefore, metallic biomaterials that exhibit properties activated by NIR are promising for further orthopedic procedures. In this work, we present an adapted electroforming approach to attain a biomorphic nano-holed TiO2 coating on Ti6Al4V alloy. Through a precise control of the anodization conditions, structures revealed the formation of localized nano-pores arranged in a periodic assembly. This specific organization provoked higher stability against thermal oxidation and precise hydrophobic wettability behavior according to Cassie-Baxter's model; both characteristics are a prerequisite to ensure a favorable biological response in an implantable structure for guided bone regeneration. In addition, the periodically arranged sub-wavelength-sized unit cell on the metallic-dielectric structure exhibits a peculiar optical response, which results in higher NIR reflectivity. Accordingly, we have proved that this effect enhances the efficiency of the scattering processes and provokes a significant improvement of light confinement producing a spontaneous NIR fluorescence emission. The combination of the already favorable mechanical and biocompatibility properties of Ti6Al4V, along with suitable thermal stability, wetting, and electro-optical behavior, opens a promising path toward strategic bone therapeutic procedures.