Synthesis of monodispersed Ag-doped bioactive glass nanoparticles via surface modification

© 2016 by the authors.Monodispersed spherical Ag-doped bioactive glass nanoparticles (Ag-BGNs) were synthesized by a modified Stöber method combined with surface modification. The surface modification was carried out at 25, 60, and 80 °C, respectively, to investigate the influence of processing temperature on particle properties. Energy-dispersive X-ray spectroscopy (EDS) results indicated that higher temperatures facilitate the incorporation of Ag. Hydroxyapatite (HA) formation on Ag-BGNs was detected upon immersion of the particles in simulated body fluid for 7 days, which indicated that Ag-BGNs maintained high bioactivity after surface modification. The conducted antibacterial assay confirmed that Ag-BGNs had an antibacterial effect on E. coli. The above results thereby suggest that surface modification is an effective way to incorporate Ag into BGNs and that the modified BGNs can remain monodispersed as well as exhibit bioactivity and antibacterial capability for biomedical applications

Protein Engineering of the Calb Lipase to Synthesize Fragrance Compounds

Abstract A computationally-guided semi-rational protein design approach was used to improve the enzymatic selectivity and catalytic efficiency of Pseudozyma antarctica lipase B (CalB) to synthesize methyl salicylate and methyl cinnamate. These fatty acid esters have significant relevance as flavoring and fragrance compounds in the biotechnological industry. Moreover, CalB is a highly active lipase that is widely used for the enzymatic hydrolysis and synthesis of esters, offering potential for the biological production of flavoring agents. However, the relatively confined organization of its active site precludes the recognition of bulky and aromatic substrates. To overcome this limitation, in silico docking analyses of CalB were undertaken to identify amino acid residues involved in precursor binding and recognition. These “hot spots” were subjected to combinatorial mutagenesis to yield three generations of CalB libraries per substrate. A surrogate substrate was used to screen for synthetic activity and evaluation of the new CalB variants revealed mutations giving rise to significant increase in synthetic activity relative to wild-type CalB. Ultimately, the best CalB variant could serve as a template to develop an E. coli whole-cell biocatalyst suitable for industrial enzymatic synthesis of methyl salicylate.</p

Chitosan nanocomposites based on distinct inorganic fillers for biomedical applications

AbstractChitosan (CHI), a biocompatible and biodegradable polysaccharide with the ability to provide a non-protein matrix for tissue growth, is considered to be an ideal material in the biomedical field. However, the lack of good mechanical properties limits its applications. In order to overcome this drawback, CHI has been combined with different polymers and fillers, leading to a variety of chitosan-based nanocomposites. The extensive research on CHI nanocomposites as well as their main biomedical applications are reviewed in this paper. An overview of the different fillers and assembly techniques available to produce CHI nanocomposites is presented. Finally, the properties of such nanocomposites are discussed with particular focus on bone regeneration, drug delivery, wound healing and biosensing applications

Surface functionalisation of sol-gel-based bioactive glass scaffolds for drug delivery

ITN FP-7 project “GlaCERCo

Electrophoretic deposition of composite coatings based on alginate matrix/45S5 bioactive glass particles doped with B, Zn or Sr

In this research work composite coatings made of alginate and 45S5 bioactive glass particles doped with B, Zn or Sr were synthesized by means of electrophoretic deposition and characterized from morphological, compositional, thermogravimetric, mechanical and electrochemical points of view. The developed coatings were also subjected to in vitro test in SBF solution to evaluate their ability to induce hydroxyapatite precipitation and cytocompatibility evaluation using human primary fibroblasts. The obtained results demonstrated a good homogeneity of the coatings, high adhesion and a protective behavior towards the substrate. The thermogravimetric analysis proved that the glass amount was constant before and after the deposition and all the investigated coatings promoted the deposition of hydroxyapatite but with different kinetics. Since the Zn containing coating showed the best bioactive behavior it was subjected to cytocompatibility test, which demonstrated, after an initial reduction of cell viability, a good cell proliferation and the production of collagen from the ECM. These findings suggest that the obtained coatings are promising materials to coat metallic prosthetic devices