Hyaluronic Acid/Chitosan Coacervate-Based Scaffolds

Chitosan-chloride (CHI) and sodium hyaluronate (HA), two semiflexible biopolymers, self-assemble to form nonstoichiometric coacervates. The effect of counterions was briefly investigated by preparing HA/CHI coacervates in either CaCl₂ or NaCl solutions to find only a small difference in their tendency to coacervate. Higher water content in coacervates within CaCl₂ was attributed to the chaotropic nature of Ca²⁺ ions. This effect was also evidenced with smaller pore sizes for coacervates in NaCl. Besides, for coacervation of chitosan-glutamate (CHI-G) with HA, dynamic light scattering at different charge ratios indicated a wider coacervation region for the HA/CHI-G pair than the HA/CHI. This was attributed to the chaotropic and “soft” ion nature of glutamate compared to chloride as a counterion of chitosan. Positive zeta potential values for both coacervate suspensions were explained by the contribution of charge mismatch, chain semiflexibility, and intra- and intercomplex disproportionation. Finally, HA/CHI coacervates were used to encapsulate bone marrow stem cells. While cell viabilities in HA/CHI coacervates were remarkable up to 21 days, their well-spread morphology has proved that HA/CHI coacervates are promising scaffolds for cartilage tissue engineering

Poly( amino acid)-based fibrous scaffolds modified with surface-pendant peptides for cartilage tissue engineering

In this study, fibrous scaffolds based on poly(gamma-benzyl-L-glutamate) (PBLG) were investigated in terms of the chondrogenic differentiation potential of human tooth germ stem cells (HTGSCs). Through the solution-assisted bonding of the fibres, fully connected scaffolds with pore sizes in the range 20-400 mu m were prepared. Biomimetic modification of the PBLG scaffolds was achieved by a two-step reaction procedure: first, aminolysis of the PBLG fibres' surface layers was performed, which resulted in an increase in the hydrophilicity of the fibrous scaffolds after the introduction of N-5-hydroxyethyl-L-glutamine units; and second, modification with the short peptide sequence azidopentanoyl-GGGRGDSGGGY-NH2, using the 'click' reaction on the previously modified scaffold with 2-propynylside-chains, was performed. Radio-assay of the I-125-labelled peptide was used to evaluate the RGD density in the fibrous scaffolds ( which varied in the range 10(-3) -10 pM/cm(2)). All the PBLG scaffolds, especially with density 90 +/- 20 fM/cm(2) and 200 +/- 100 fM/cm(2) RGD, were found to be potentially suitable for growth and chondrogenic differentiation of HTGSCs. Copyright (C) 2015 John Wiley & Sons, Ltd

Surface modification of Ti6Al4V by micro-arc oxidation in AgC2H3O2-containing electrolyte

This study focuses on the biological properties of Ti6Al4V after employing micro-arc oxidation in sodium phosphateand calcium acetate-containing electrolyte with and without addition of silver acetate. After micro-arc oxidation process, structural features of the surfaces were analyzed by using an energy dispersive X-ray spectrometer equipped scanning electron microscope, an X-ray diffractometer and a Fourier transform infrared spectroscope. The micro-arc oxidation process generated multilayer coatings composed of carbonated hydroxyapatite and titanium oxide layers, while addition of 0.001 mol/l silver acetate into the electrolyte caused incorporation of 0.7 wt.% silver into the coating. The antibacterial activity of the coatings was analyzed by using the Streptococcus mutans American Type Culture Collection 25175 strain. The metabolic activity of the multilayers was evaluated in cultures of a human primary osteogenic sarcoma cell line (Saos-2). In short, incorporation of 0.7 wt.% silver in the form of agglomerated particles, mostly around the micropores of the titanium oxide layer, enhanced the antibacterial efficiency of the fabricated coating to some extent without altering the cell proliferation considerably

Surface modification of Ti6Al4V by micro-arc oxidation in AgC 2

This study focuses on the biological properties of Ti6Al4V after employing micro-arc oxidation in sodium phosphateand calcium acetate-containing electrolyte with and without addition of silver acetate. After micro-arc oxidation process, structural features of the surfaces were analyzed by using an energy dispersive X-ray spectrometer equipped scanning electron microscope, an X-ray diffractometer and a Fourier transform infrared spectroscope. The micro-arc oxidation process generated multilayer coatings composed of carbonated hydroxyapatite and titanium oxide layers, while addition of 0.001 mol/l silver acetate into the electrolyte caused incorporation of 0.7 wt.% silver into the coating. The antibacterial activity of the coatings was analyzed by using the Streptococcus mutans American Type Culture Collection 25175 strain. The metabolic activity of the multilayers was evaluated in cultures of a human primary osteogenic sarcoma cell line (Saos-2). In short, incorporation of 0.7 wt.% silver in the form of agglomerated particles, mostly around the micropores of the titanium oxide layer, enhanced the antibacterial efficiency of the fabricated coating to some extent without altering the cell proliferation considerably

Optimisation of micro-arc oxidation electrolyte for fabrication of antibacterial coating on titanium

This study has been carried out to optimise the silver (Ag) content of the coating synthesised on commercially pure titanium (Cp-Ti, Grade 4) for biomedical applications by micro-arc oxidation (MAO) process. The MAO process has been conducted in electrolytes containing silver acetate (AgC2H3O2) at different concentrations between 0 and 0.002 mol L-1. When compared to the base electrolyte, coatings synthesised in >= 0.001 mol L-1 AgC2H3O2 added electrolytes exhibited an antibacterial efficiency of 99.8% against Staphylococcus aureus (S. aureus). Detailed examination revealed that the presence of 0.01 mol L-1 AgC2H3O2 in the electrolyte resulted in incorporation of 1.4 wt-% Ag into fabricated coating consisting mainly of outer hydroxyapatite (HA) and inner titanium oxide (TiO2) layers. In comparison to the Ag-free coating, 1.4 wt-% Ag in the coating lowered the proliferation of SAOS-2 cells, which still tended to grow at a relatively low rate with increasing culturing time