Bioactivity and Antibacterial Behaviors of Nanostructured Lithium-Doped Hydroxyapatite for Bone Scaffold Application.

The material for bone scaffold replacement should be biocompatible and antibacterial to prevent scaffold-associated infection. We biofunctionalized the hydroxyapatite (HA) properties by doping it with lithium (Li). The HA and 4 Li-doped HA (0.5, 1.0, 2.0, 4.0 wt.%) samples were investigated to find the most suitable Li content for both aspects. The synthesized nanoparticles, by the mechanical alloying method, were cold-pressed uniaxially and then sintered for 2 h at 1250 °C. Characterization using field-emission scanning electron microscopy (FE-SEM) revealed particle sizes in the range of 60 to 120 nm. The XRD analysis proved the formation of HA and Li-doped HA nanoparticles with crystal sizes ranging from 59 to 89 nm. The bioactivity of samples was investigated in simulated body fluid (SBF), and the growth of apatite formed on surfaces was evaluated using SEM and EDS. Cellular behavior was estimated by MG63 osteoblast-like cells. The results of apatite growth and cell analysis showed that 1.0 wt.% Li doping was optimal to maximize the bioactivity of HA. Antibacterial characteristics against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were performed by colony-forming unit (CFU) tests. The results showed that Li in the structure of HA increases its antibacterial properties. HA biofunctionalized by Li doping can be considered a suitable option for the fabrication of bone scaffolds due to its antibacterial and unique bioactivity properties.

Composite electrospun nanofibers of reduced graphene oxide grafted with poly(3-dodecylthiophene) and poly(3-thiophene ethanol) and blended with polycaprolactone.

In this paper, an effective method was employed for preparation of nanofibers using conducting polymer-functionalized reduced graphene oxide (rGO). First, graphene oxide (GO) was obtained from graphite by Hommer method. GO was reduced to rGO by NaBH4 and covalently functionalized with a 3-thiophene acetic acid (TAA) by an esterification reaction to reach 3-thiophene acetic acid-functionalized reduced graphene oxide macromonomer (rGO-f-TAAM). Afterward, rGO-f-TAAM was copolymerized with 3-dodecylthiophene (3DDT) and 3-thiophene ethanol (3TEt) to yield rGO-f-TAA-co-PDDT (rGO-g-PDDT) and rGO-f-TAA-co-P3TEt (rGO-g-PTEt), which were confirmed by Fourier transform infrared spectra. The grafted materials depicted better electrochemical properties and superior solubilities in organic solvents compared to GO and rGO. The soluble rGO-g-PDDT and rGO-g-PTEt composites blended with polycaprolactone were fabricated by electrospinning, and then cytotoxicity, hydrophilicity, biodegradability and mechanical properties were investigated. The grafted rGO composites exhibited a good electroactivity behavior, mainly because of the enhanced electrochemical performance. The electrospun nanofibers underwent degradation about 7 wt% after 40 days, and the fabricated scaffolds were not able to induce cytotoxicity in mouse osteoblast MC3T3-E1 cells. The soluble conducting composites developed in this study are utilizable in the fabrication of nanofibers with tissue engineering application.

Development of novel electrically conductive scaffold based on hyperbranched polyester and polythiophene for tissue engineering applications.

A novel electrically conductive scaffold containing hyperbranched aliphatic polyester (HAP), polythiophene (PTh), and poly(ε-caprolactone) (PCL) for regenerative medicine application was succesfully fabricated via electrospinning technique. For this purpose, the HAP (G4; fourth generation) was synthesized via melt polycondensation reaction from tris(methylol)propane and 2,2-bis(methylol)propionic acid (bis-MPA). Afterward, the synthesized HAP was functionalized with 2-thiopheneacetic acid in the presence of N,N-dicyclohexyl carbodiimide, and N-hydroxysuccinimide as coupling agent and catalyst, respectively, to afford a thiophene-functionalized G4 macromonomer. This macromonomer was subsequently used in chemical oxidation copolymerization with thiophene monomer to produce a star-shaped PTh with G4 core (G4-PTh). The solution of the G4-PTh, and PCL was electrospun to produce uniform, conductive, and biocompatible nanofibers. The conductivity, hydrophilicity, and mechanical properties of these nanofibers were investigated. The biocompatibility of the electrospun nanofibers were evaluated by assessing the adhesion and proliferation of mouse osteoblast MC3T3-E1 cell line and in vitro degradability to demonstrate their potential uses as a tissue engineering scaffold. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2673-2684, 2016.