Single-Step Process for Titanium Surface Micro- and Nano-Structuring and In Situ Silver Nanoparticles Formation by Ultra-Short Laser Patterning

Ultra-short laser (USL)-induced surface structuring combined with nanoparticles synthesis by multiphoton photoreduction represents a novel single-step approach for commercially pure titanium (cp-Ti) surface enhancement. Such a combination leads to the formation of distinct topographical features covered by nanoparticles. The USL processing of cp-Ti in an aqueous solution of silver nitrate (AgNO3) induces the formation of micron-sized spikes surmounted by silver nanoparticles (AgNPs). The proposed approach combines the structuring and oxidation of the Ti surface and the synthesis of AgNPs in a one-step process, without the use of additional chemicals or a complex apparatus. Such a process is easy to implement, versatile and sustainable compared to alternative methodologies capable of obtaining comparable results. Antimicrobial surfaces on medical devices (e.g., surgical tools or implants), for which titanium is widely used, can be realized due to the simultaneous presence of AgNPs and micro/nano-structured surface topography. The processed surfaces were examined by means of a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and Raman spectroscopy. The surface morphology and the oxidation, quality and quantity of AgNPs were analyzed in relation to process parameters (laser scanning speed and AgNO3 concentration), as well as the effect of AgNPs on the Raman signal of Titanium oxide

The Alzheimer's disease amyloid-β peptide affects the size-dynamics of raft-mimicking Lo domains in GM1-containing lipid bilayers

International audience† Electronic supplementary information (ESI) available: Films illustrating the effect of A(1-42) on photoinduced spinodal decomposition in GUVs, speed acceletated x 12: Movie_1_GUVs_PC-SM-Chol_10%GM1_withoutAb_20Cx12.avi Movie_2_GUVs_PC-SM-Chol_10%GM1_withAb_20Cx12.avi, Movie_3_GUVs_PC-SM-Chol_10%GM1_withoutAb_14Cx12.avi Movie_4_GUVs_PC-SM-Chol_10%GM1_withAb_14Cx12.avi Alzheimer's disease (AD) is characterized by the overproduction of the amyloid- peptide (A) which forms fibrils under the influence of raft microdomains containing the ganglioside GM1. Raft-mimicking artificial liquid ordered (Lo) domains containing GM1 enhance amyloid- polymerization. Other experiments suggest that A binds preferably to the non-raft liquid disordered (Ld) phase rather than to the Lo phase in the presence of GM1. Here, the interaction of A(1-42) with GM1-containing biphasic Lo-Ld giant vesicles was investigated. Fluorescence colocalisation experiments confirm that A(1-42) binds preferentially to the Ld phase. The effect of A(1-42) on Lo-Ld size dynamics was studied using photoinduced spinodal decomposition which mimics the nanodomain-microdomain raft coalescence. A affects the kinetics of the coarsening phase and the size of the resulting microdomains. The effect depends on which phase is majoritary: when Lo microdomains are formed inside an Ld phase, their growth rate becomes slower and their final size smaller in the presence of A(1-42), whereas when Ld microdomains are formed inside an Lo phase, growth rate becomes faster and final size larger. Fluorimetric measurements on large vesicles using the probe LAURDAN indicate that A(1-42) binding respectively increases or decreases the packing of the Ld phase in the presence or absence of GM1. The differential effects of A on spinodal decomposition are accordingly interpreted as resulting from distinct effects of the peptide on Lo-Ld line tension modulated by GM1. Such modulating effect of A on domain dynamics could be important for lipid rafts in signaling disorders in AD as well as in A fibrillation

Emptying the β‑Cyclodextrin Cavity by Light: Photochemical Removal of the <i>trans</i>-Chalcone of 4′,7-Dihydroxyflavylium

The interaction between the network of chemical reactions of the compound 4′,7-dihydroxyflavylium and β-cyclodextrin was studied by means of pH jumps, followed by UV–vis absorption, flash photolysis, stopped flow, and NMR. The <i>trans</i>-chalcone is the network species exhibiting the strongest interaction with the host. In moderately acidic medium, 95% of the <i>trans</i>-chalcone, 2.5 × 10^–5 M, in the presence of β-cyclodextrin, 9 × 10^–3 M, is expected to fill the host cavity (association constant 2.2 × 10³ M^–1). In contrast, flavylium cation does not interact (association constant ≈ 0). Irradiation of the <i>trans</i>-chalcone in the presence of β-cyclodextrin 9 mM leads to the flavylium cation appearance. Light is thus capable of removing the <i>trans</i>-chalcone from the β-cyclodextrin, leaving the cavity empty. The system is reversible and <i>trans</i>-chalcone goes back to the initial state upon switching off the light due to the thermodynamic favorable conversion of flavylium cation to <i>trans</i>-chalcone in the presence of β-cyclodextrin

Single-Step Process for Titanium Surface Micro- and Nano-Structuring and In Situ Silver Nanoparticles Formation by Ultra-Short Laser Patterning

Ultra-short laser (USL)-induced surface structuring combined with nanoparticles synthesis by multiphoton photoreduction represents a novel single-step approach for commercially pure titanium (cp-Ti) surface enhancement. Such a combination leads to the formation of distinct topographical features covered by nanoparticles. The USL processing of cp-Ti in an aqueous solution of silver nitrate (AgNO3) induces the formation of micron-sized spikes surmounted by silver nanoparticles (AgNPs). The proposed approach combines the structuring and oxidation of the Ti surface and the synthesis of AgNPs in a one-step process, without the use of additional chemicals or a complex apparatus. Such a process is easy to implement, versatile and sustainable compared to alternative methodologies capable of obtaining comparable results. Antimicrobial surfaces on medical devices (e.g., surgical tools or implants), for which titanium is widely used, can be realized due to the simultaneous presence of AgNPs and micro/nano-structured surface topography. The processed surfaces were examined by means of a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and Raman spectroscopy. The surface morphology and the oxidation, quality and quantity of AgNPs were analyzed in relation to process parameters (laser scanning speed and AgNO3 concentration), as well as the effect of AgNPs on the Raman signal of Titanium oxide