Enhanced biomedical heat-triggered carriers via nanomagnetism tuning in ferrite-based nanoparticles

Biomedical nanomagnetic carriers are getting a higher impact in therapy and diagnosis schemes while their constraints and prerequisites are more and more successfully confronted. Such particles should possess a well-defined size with minimum agglomeration and they should be synthesized in a facile and reproducible high-yield way together with a controllable response to an applied static or dynamic field tailored for the specific application. Here, we attempt to enhance the heating efficiency in magnetic particle hyperthermia treatment through the proper adjustment of the core–shell morphology in ferrite particles, by controlling exchange and dipolar magnetic interactions at the nanoscale. Thus, core–shell nanoparticles with mutual coupling of magnetically hard (CoFe2O4) and soft (MnFe2O4) components are synthesized with facile synthetic controls resulting in uniform size and shell thickness as evidenced by high resolution transmission electron microscopy imaging, excellent crystallinity and size monodispersity. Such a magnetic coupling enables the fine tuning of magnetic anisotropy and magnetic interactions without sparing the good structural, chemical and colloidal stability. Consequently, the magnetic heating efficiency of CoFe2O4 and MnFe2O4 core–shell nanoparticles is distinctively different from that of their counterparts, even though all these nanocrystals were synthesized under similar conditions. For better understanding of the AC magnetic hyperthermia response and its correlation with magnetic-origin features we study the effect of the volume ratio of magnetic hard and soft phases in the bimagnetic core−shell nanocrystals. Eventually, such particles may be considered as novel heating carriers that under further biomedical functionalization may become adaptable multifunctional heat-triggered nanoplatforms

Lipid production by Rhodosporidium toruloides from biodiesel-derived glycerol in shake flasks and bioreactor: Impact of initial C/N molar ratio and added onion-peel extract

Rhodosporidium toruloides NRRL Y-27012 grown in glycerol, produced yeast biomass and secondary metabolites as lipids (L) and intra-cellular polysaccharides (IPS) in trials under nitrogen limitation (initial C/N molar ratios ≈ 50, ≈ 100, ≈ 160 and ≈ 240). The initial glycerol (Glol0) concentration for all experiments was ≈ 90 g/L. The yeast demonstrated significant dry cell weight (DCW) production irrespective of the C/N ratio employed, ranging between 19 and 29 g/L. The optimum C/N ratio medium was that of 100 moles/moles, where a DCWmax = 24.5 g/L containing c. 50% w/w of lipids was recorded. Endopolysaccharides presented indeed impressive values (≥ 50% w/w) even at the very early growth steps, while IPS/DCW values decreased as the fermentation proceeded, with simultaneous increase of L/DCW values. Experiments were also conducted in media with a hydroglycerolic extract of onion peels (at 40 mL/L), while a blank experiment (no extract) was also realized. The trial with the added extract was performed under both aseptic (previous sterilization) and non-aseptic (previous thermal treatment at T = 100 °C; 5 min) conditions. The aseptic experiment with the added extract resulted in a relative decrease in lipid production in relation to the control (L=8.6 g/L in the control vs L = 6.2 g/L with the extract). Under non-aseptic conditions, lipid production was slightly lower (L = 5.2 g/L). Finally, the optimum trial in shake flasks was scaled-up in a batch bioreactor, and higher glycerol assimilation rate, and biomass and lipid production occurred compared to the flask trial (final DCW and lipid values ≈27 g/L and 13.5 g/L respectively). Cellular lipids, rich in palmitic and oleic acid, were mainly composed of neutral fractions. Phospholipids were more saturated than the neutral lipids. © 2022 Elsevier Lt

Plasmonic gold-silver alloy on TiO2 photocatalysts with tunable visible light activity

International audienceAdaptation of the photoresponse of anatase TiO2 to match the solar spectrum is an important scientific challenge. Modification of TiO2 with noble metal nanoparticles displaying surface plasmon resonance effects is one of the promising approaches. Surface plasmon resonance typically depends on chemical composition, size, shape and spatial organization of the metal nanoparticles in contact with TiO2. AuxAg(1-x) alloy nanoparticles display strong composition-dependent surface plasmon resonance in the visible light region of the spectrum. In this work, a general strategy is presented to prepare plasmonic TiO2-based photocatalysts with a visible light response that can be accurately tuned over a broad range of the spectrum. The application as self-cleaning material toward the degradation of stearic acid is demonstrated for a plasmonic TiO2 photocatalyst displaying visible light photoactivity at the intensity maximum of solar light around 490nm. © 2014 Elsevier B.V

A novel approach for skin infections: Controlled release topical mats of poly(lactic acid)/poly(ethylene succinate) blends containing Voriconazole

The oral and injectable formulations of Voriconazole (VRZ), a known antifungal agent with low solubility, seem to cause severe side effects. Consequently, topical application of VRZ could be advantageous for skin fungal infections. In this study, VRZ embedded in a polymeric matrix composed of biocompatible poly(lactic acid) (PLA) and poly(ethylene succinate) (PESu). The mats were prepared via solvent evaporation and fully characterized by Fourier-Transformed Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), in vitro hydrolysis and release studies. The prepared blends defined as immiscible by DSC and SEM while FTIR spectroscopy did not disclose noticeable interactions between the polymers. It was found that hydrolysis was improved by increasing PESu content into the blend. VRZ loaded blends spectra exhibit slight differentiation compared to neat blends while the absence of VRZ melting peak, as DSC illustrated, indicated drug amorphization. Lastly, in vitro release studies depicted a controlled release pattern dependent on mats' hydrolysis degree. An improved antifungal activity of mats was detected by disc diffusion method against various microorganisms. Ex vivo studies of VRZ did not determine high permeation while histopathology results using mice were profitable. The irritation experiments displayed that the mats did not induce any skin irritation. © 201

Novel poly(butylene succinate) nanocomposites containing strontium hydroxyapatite nanorods with enhanced osteoconductivity for tissue engineering applications

Three series of poly(butylene succinate) (PBSu) nanocomposites containing 0.5, 1 and 2.5 wt% strontium hydroxyapatite [Sr5(PO4)3OH] nanorods (SrHAp nrds) were prepared by in situ polymerisation. The structural effects of Sr5(PO4)3OH nanorods, for the different concentrations, inside the polymeric matrix (PBSu), were studied through high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). HAADF-STEM measurements revealed that the SrHAp nanorods at low concentrations are dispersed inside the polymeric PBSu matrix while in 1 wt% some aggregates are formed. These aggregations affect the mechanical properties giving an enhancement for the concentration of 0.5 wt% SrHAp nrds in tensile strength, while a reduction is recorded for higher loadings of the nanofiller. Studies on enzymatic hydrolysis revealed that all nanocomposites present higher hydrolysis rates than neat PBSu, indicating that nanorods accelerate the hydrolysis degradation process. In vitro bioactivity tests prove that SrHAp nrds promote the formation of hydroxyapatite on the PBSu surface. All nanocomposites were tested also in relevant cell culture using osteoblast-like cells (MG-63) to demonstrate their biocompatibility showing SrHAp nanorods support cell attachment

Novel poly(butylene succinate) nanocomposites containing strontium hydroxyapatite nanorods with enhanced osteoconductivity for tissue engineering applications

Three series of poly(butylene succinate) (PBSu) nanocomposites containing 0.5, 1 and 2.5 wt% strontium hydroxyapatite [Sr5(PO4)3OH] nanorods (SrHAp nrds) were prepared by in situ polymerisation. The structural effects of Sr5(PO4)3OH nanorods, for the different concentrations, inside the polymeric matrix (PBSu), were studied through high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). HAADF-STEM measurements revealed that the SrHAp nanorods at low concentrations are dispersed inside the polymeric PBSu matrix while in 1 wt% some aggregates are formed. These aggregations affect the mechanical properties giving an enhancement for the concentration of 0.5 wt% SrHAp nrds in tensile strength, while a reduction is recorded for higher loadings of the nanofiller. Studies on enzymatic hydrolysis revealed that all nanocomposites present higher hydrolysis rates than neat PBSu, indicating that nanorods accelerate the hydrolysis degradation process. In vitro bioactivity tests prove that SrHAp nrds promote the formation of hydroxyapatite on the PBSu surface. All nanocomposites were tested also in relevant cell culture using osteoblast-like cells (MG-63) to demonstrate their biocompatibility showing SrHAp nanorods support cell attachment