Porous Poly‐l‐lactide (PLLA) scaffolds and PLLA/nanohydroxyapatite (nHA) composite scaffolds with interconnected pore networks and a porosity of over 90% were fabricated with lyophilization techniques. In this study, the degradation behavior of PLLA and PLLA/nHA composite scaffolds is investigated over 8 weeks in phosphate buffer solution at 37°C. Thermal analysis using differential scanning calorimetry (DSC) showed that the percent crystallinity of all the samples increased by approximately 10%, which represents a considerable increase in the glass transition temperature. The melting range enthalpy of the scaffolds did not change to lower temperatures as would be expected. The spectroscopic analysis performed by Fourier transform infrared spectroscopy suggested that nHA particles should not appreciably affect the absorbance pattern when evenly mixed with the PLLA. This is consistent with the analysis of the scaffold microstructure and morphology with scanning electron microscopy, which drew a low content of nHA with no significant effect on solvent crystallization or pore structure. The compressive modulus and the yield strength of the scaffolds were investigated in conjunction with the study of their degradation rates. In comparison with the mechanical properties of the PLLA scaffolds, which remained largely unchanged, those of the PLLA/nHA composite scaffolds decreased as the degradation progressed. POLYM. ENG. SCI., 54:2571–2578, 2014. © 2013 Society of Plastics Engineers

The influence of copolymer composition on Poly(Lactide-co-Glycolide)/nanohydroxyapatite (PLGA/nHA) composite scaffolds is studied in the context of bone tissue engineering and regenerative medicine. The composite scaffolds are fabricated by thermally-induced phase separation and the effect of bioactive nanoparticles on their in vitro degradation in phosphate-buffered solution at 37 °C is analyzed over eight weeks. The indirect cytotoxicity evaluation of the samples followed an adaptation of the ISO 10993-5 standard test method. Based on the measurement of their molecular weight, molar mass, pH, water absorption and dimensions, the porous scaffolds of PLGA with a lower lactide/glycolide (LA/GA) molar ratio degraded faster due to their higher hydrophilicity. All of the samples without and with HA are not cytotoxic, demonstrating their potential for tissue engineering applications.

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Biodegradable poly(L-lactide-co-glycolide) (PLGA)/multiwalled carbon nanotubes (MWCNTs) scaffolds produced by thermally induced phase separation (TIPS) are studied for bone regeneration. Their magnetic properties, cytotoxicity, and in vitro degradation are investigated. Certain properties are analyzed at 37 C over 16 weeks in phosphate buffer saline (PBS) solution, as a function of degradation time: morphology, mass loss, pH value of PBS, and thermal behavior. The presence of small quantities of nanotubes in the scaffolds, ≤0.5 wt %, leads to a weak magnetic response although the PLGA was diamagnetic. The incorporation of MWCNTs in the scaffolds generated a morphology and a very different process of in vitro degradation than might be expected in a PLGA scaffold. The in vitro degradation process started on week 13 and rapidly advanced, although the structural integrity of the scaffolds was maintained and no collapse of the structure occurred. Cytotoxicity tests on the samples showed cytotoxicity behavior at concentrations of over 0.3 wt % MWCNTs.

We investigated the effect of bioactive nanoparticles on the in-vitro degradation of PLCL and PLCL/nHA composite scaffolds. The concentration of nanohydroxyapatite significantly affected the degradation rate. An increase in the crystallinity of the amorphous portion of the polymer was observed. This increased crystallinity was more pronounced in the pure PLCL samples than in those with more nHA. During the degradation process, we observed the appearance of multiple micropores on the scaffold walls as the hydrolysis process progressed and, by the sixth week, the remains of the degradation products were visible on the pore walls.