Journal of Materials Science: Materials in Medicine

Durand, Jean-Cédric; Jacquot, Bruno; Salehi, Hamideh; Margerit, Jacques; Cuisinier, Frédéric

doi: 10.1007/s10856-012-4616-4pmid: 22447122

The aim of this study was to evaluate the changes in the transition layer at the interface between yttria partial stabilized tetragonal zirconia polycrystalline (Y-TZP) core and veneering feldspathic ceramic (VITA VM®9), under different manufacturing methods. Confocal Raman microscopy and energy dispersive X-ray spectroscopy (EDS) analyses were carried out on tapered veneered cross sections of the interface. For some samples, an additional firing of the core was used, as the application of an optional liner material between the core and veneer. Single Raman spectra were distinguishable between Y-TZP and the veneering materials. VM®9 and liner spectra were broadly superimposable. No substantial differences appeared in their chemical elemental composition. 2D Raman images and EDS analysis emphasized changes in the interdiffusion thickness; the additional firing of the core decreased the interdiffusion zone, and the highest firing temperature of the liner increased the interdiffusion zone. These results, which will help us understand the changes in this transition layer, are discussed.

Kawashita, Masakazu; Taninai, Koji; Li, Zhixia; Ishikawa, Kunio; Yoshida, Yasuhiro

doi: 10.1007/s10856-012-4614-6pmid: 22426746

We prepared low-crystalline apatite nanoparticles and coated them onto a surface of a Au/Cr-plated quartz substrate by the electrophoretic deposition (EPD) method or by using a self-assembled monolayer of 11-mercaptoundecanoic acid (SAM method). Low-crystalline apatite nanoparticles around 10 nm in size with extremely low contents of undesirable residual products were obtained by adding (NH4)2HPO4 aqueous droplets into a modified synthetic body fluid solution that contained Ca(CH3COO)2. The apatite nanoparticles were successfully coated by either the EPD method or the SAM method; the nanoparticle coating achieved by the SAM method was more uniform than that achieved by the EPD method. The present SAM method is expected to be a promising technique for obtaining a quartz substrate coated with apatite nanoparticles, which can be used as a quartz crystal microbalance device.

Panzavolta, S.; Bracci, B.; Focarete, M.; Gualandi, C.; Bigi, A.

doi: 10.1007/s10856-012-4618-2pmid: 22528068

In this study we investigated the influence of electrospun polymer fibers on the properties of a α-tricalcium phosphate/gelatin biomimetic cement. To this aim, we added different amounts of poly(l-lactic acid) and poly(lactide-co-glycolide) fibers to the cement composition. Fibers enrichment provoked a significant reduction of both initial and final setting times. Moreover electrospun polymer fibers slowed down the conversion of α-tricalcium phosphate into calcium deficient hydroxyapatite. As a result, the final cements were more compact than the control cement, because of the smaller crystal dimensions and reduced crystallinity of the apatitic phase. The compressive strength, σb, and Young’s modulus, E, of the control cement decreased significantly after 40 days soaking in physiological solution, whereas the more compact microstructure enabled fiber reinforced cements to maintain their mechanical properties in the long term.

Delabarde, Claire; Plummer, Christopher; Bourban, Pierre-Etienne; Månson, Jan-Anders

doi: 10.1007/s10856-012-4619-1pmid: 22437691

Supercritical carbon dioxide processing of poly-l-lactide (PLLA)/hydroxyapatite (nHA) nanocomposites was investigated as a means to prepare foams suitable as scaffolds in bone tissue engineering applications. For given foaming parameters, addition of nHA to the PLLA gave reduced cell sizes and improved homogeneity in the size distribution, but did not significantly affect the degree of crystallinity, which remained of the order of 50 wt% in all the foams. The compressive modulus and strength were primarily influenced by the porosity and there was no significant reinforcement of the matrix by the nHA. The mechanical properties of the foams were nevertheless comparable with those of trabecular bone, and by adjusting the saturation pressure and depressurization rate it was possible to generate porosities of about 85 %, an interconnected morphology and cell diameters in the range 200–400 μm from PLLA containing 4.17 vol% nHA, satisfying established geometrical requirements for bone replacement scaffolds.

Pagoulatou, Eirini; Triantaphyllidou, Irene-Eva; Vynios, Demitrios; Papachristou, Dionysios; Koletsis, Efstratios; Deligianni, Despina; Mavrilas, Dimosthenis

doi: 10.1007/s10856-012-4620-8pmid: 22454140

To achieve natural scaffolds for tissue engineering applications we decellularized bovine pericardial (BP) tissues according to two different protocols: a novel treatment based on Triton® X-100 (12 h, 4 °C) (BP1) and a trypsin/EDTA treatment (37 °C, 48 h) (BP2). Results were compared with commercially available acellular xenogeneic biomaterials, Veritas® and Collamed®. Biomechanical characteristics, high (Eh) and low (El) modulus of elasticity, of the fresh untreated tissue varied with the anatomical direction (apex to base (T) to transverse (L)) (mean ± SDEV): (41.63 ± 14.65–48.12 ± 10.19 MPa and 0.27 ± 0.05–0.30 ± 0.12 MPa respectively). BP1 had no mechanical effect (44.65 ± 19.73–52.67 ± 7.59 MPa and 0.37 ± 0.14–0.37 ± 0.11 MPa, respectively) but BP2 resulted in significant decrease in Eh and El (20.96 ± 8.17–36.82 ± 3.23 MPa and 0.20 ± 0.06–0.23 ± 0.06 MPa). Hysteresis ratio (h) varied (19–26 % of the loading energy) independently of anatomical direction. Glycosaminoglycans content was unaffected by BP1, while 22 % of chondroitin/dermatan sulphate and 60 % of hyaluronan were removed after BP2 treatment. Endothelial cell adhesion was achieved after 24 h and 3 days cell culture.

Bellucci, D.; Chiellini, F.; Ciardelli, G.; Gazzarri, M.; Gentile, P.; Sola, A.; Cannillo, V.

doi: 10.1007/s10856-012-4622-6pmid: 22441671

A new protocol, based on a modified replication method, is proposed to obtain bioactive glass scaffolds. The main feature of these samples, named “shell scaffolds”, is their external surface that, like a compact and porous shell, provides both high permeability to fluids and mechanical support. In this work, two different scaffolds were prepared using the following slurry components: 59 % water, 29 % 45S5 Bioglass® and 12 % polyvinylic binder and 51 % water, 34 % 45S5 Bioglass®, 10 % polyvinylic binder and 5 % polyethylene. All the proposed samples were characterized by a widespread microporosity and an interconnected macroporosity, with a total porosity of 80 % vol. After immersion in a simulated body fluid (SBF), the scaffolds showed strong ability to develop hydroxyapatite, enhanced by the high specific surface of the porous systems. Moreover preliminary biological evaluations suggested a promising role of the shell scaffolds for applications in bone tissue regeneration. As regards the mechanical behaviour, the shell scaffolds could be easily handled without damages, due to their resistant external surface. More specifically, they possessed suitable mechanical properties for bone regeneration, as proved by compression tests performed before and after immersion in SBF.

Ruckh, Timothy T.; Floreani, Rachael A.; Carroll, Derek A.; Mikhova, Krasimira; Bryers, James D.; Popat, Ketul C.

doi: 10.1007/s10856-012-4609-3pmid: 22407002

This study quantified the antibiotic release kinetics and subsequent bactericidal efficacy of rifampicin (RIF) against Gram-positive and Gram-negative bacteria under in vitro static conditions. Antibiotic-loaded scaffolds were fabricated by electrospinning poly(caprolactone) (PCL) with 10% or 20% (w/w) RIF. Scaffold fiber diameter and RIF loading were characterized, and RIF release kinetics were measured. RIF-releasing and RIF-free scaffolds were inoculated with Pseudomonas aeruginosa and Staphylococcus epidermidis, and the suspended concentration live and dead bacteria were determined by fluorescent microscopy. Adherent bacteria and biofilm formation were examined using scanning electron microscopy. Mean fiber diameters were 557 ± 399 nm for RIF-free, 402 ± 225 nm for 10% RIF, and 665 ± 402 nm for 20% RIF scaffolds. RIF release kinetics exhibited a short-burst release during the first hour, followed by a 7 h, zero-order release during which both RIF scaffolds released ~50% of their initial RIF mass loading. P. aeruginosa and S. epidermidis suspended cell populations proliferated in accordance with logarithmic growth models when exposed to control scaffolds; however both RIF-containing scaffolds completely inhibited bacterial growth in suspension and, subsequently, prevented biofilm formation within the scaffolds through the first 6 h.

Shanmuga Sundar, Saravanabhavan; Sangeetha, Dharmalingam

doi: 10.1007/s10856-012-4610-xpmid: 22476650

The recent advances in electrospinning have resulted in technologies facilitating easy drug entrapment, obtaining high surface area and thereby higher drug loading and release efficacy, burst control as well as the specific morphology which could be controlled according to the desired requirement. The present study focused on the fabrication of collagen/poly(N-isopropyl acrylamide)/chitosan complex with incorporated 5-fluorouracil, an anticancer drug by the method of electrospinning. The effect of chitosan on the fiber morphology and release kinetics was analyzed by varying its concentration. The release kinetics showed that the increase in chitosan concentration delayed the release of the drug from the fiber network. Nano hydroxyapatite was added to the fiber matrix in order to impart bioactivity, which was confirmed by studies in simulated body fluid. The addition of poly(N-isopropyl acrylamide) increased the blood compatibility of the prepared model. Thus, the model prepared to can find potential application in the field of cancer therapy as a drug-delivery agent in post-surgical treatment of cancer and as blood contacting biomaterial.

Pinto, Flávia; Da Silva-Cunha Junior, Armando; Oréfice, Rodrigo; Ayres, Eliane; Andrade, Silvia; Lima, Luiza; Lima Moura, Sandra; Da Silva, Gisele

doi: 10.1007/s10856-012-4615-5pmid: 22466817

The purpose of this study was to develop triamcinolone acetonide-loaded polyurethane implants (TA PU implants) for the local treatment of different pathologies including arthritis, ocular and neuroinflammatory disorders. The TA PU implants were characterized by FTIR, SAXS and WAXS. The in vitro and in vivo release of TA from the PU implants was evaluated. The efficacy of TA PU implants in suppressing inflammatory-angiogenesis in a murine sponge model was demonstrated. FTIR results revealed no chemical interactions between polymer and drug. SAXS results indicated that the incorporation of the drug did not disturb the polymer morphology. WAXS showed that the crystalline nature of the TA was preserved after incorporation into the PU. The TA released from the PU implants efficiently inhibited the inflammatory-angiogenesis induced by sponge discs in an experimental animal model. Finally, TA PU implants could be used as local drug delivery systems because of their controlled delivery of TA.

Matsumoto, Mariza; Caviquioli, Gustavo; Biguetti, Claudia; Holgado, Leandro; Saraiva, Patrícia; Rennó, Ana; Kawakami, Roberto

doi: 10.1007/s10856-012-4612-8pmid: 22426745

Bioactive glasses represent an interesting class of bone substitute’s biomaterials. The present study investigated the repair of bone defects filled with a novel bioactive vitroceramic (Biosilicate®), alone or in association with particulate autogenous bone grafts in calvaria defects of rabbits. After 7, 14, and 30 days the specimens were retrieved for histological, histomorphometric and immunohistochemistry analysis. Satisfactory bone formation was observed in all groups, and direct bone-biomaterial surface was noted. Histomorphometric assessment did not show statistically significant differences in bone formation among the groups and periods, except for BG group at day 14. Immunoexpression of Runx-2 was similar among the groups containing the graft and the biomaterial, being more intense than in control group. Similar result was observed for VEGF expression, especially in the last experimental period. These results revealed that Biosilicate® presented a favorable behavior, comparable to autogenous bone graft.