Influence of polylactide coating stereochemistry on mechanical and in vitro degradation properties of porous bioactive glass scaffolds for bone regeneration.

The mechanical properties of polylactide stereocomplexes (PLA SC) have been primarily studied through tensile testing, with inconsistent results, and the compressive properties of PLA SC compared to homocrystalline or amorphous PLA remain poorly understood. In this study, we coated porous bioactive glass 13-93 scaffolds with amorphous, homocrystalline, or stereocomplex PLA to investigate their mechanical and degradation properties before and after immersion in simulated body fluid. The glass scaffolds had interconnected pores and an average porosity of 76%.

Customizing the hydrolytic degradation rate of stereocomplex PLA through different PDLA architectures.

Stereocomplexation of poly(L-lactide) (PLLA) with star shaped D-lactic acid (D-LA) oligomers with different architectures and end-groups clearly altered the degradation rate and affected the degradation product patterns. Altogether, nine materials were studied: standard PLLA and eight blends of PLLA with either 30 or 50 wt % of four different D-LA oligomers. The influence of several factors, including temperature, degradation time, and amount and type of D-LA oligomer, on the hydrolytic degradation process was investigated using a fractional factorial experimental design.

From lactic acid to poly(lactic acid) (PLA): characterization and analysis of PLA and its precursors.

The quality of the monomers lactic acid and lactide as well as the chemical changes induced during polymerization and processing are crucial parameters for controlling the properties of the resulting poly(lactic acid) (PLA) products. This review presents the most important analysis and characterization methods for quality assessment of PLA and its precursors. The impurities typically present in lactic acid or lactide monomers and their possible origins and effects on resulting PLA products are discussed.

Readily controllable step-growth polymerization method for poly(lactic acid) copolymers having a high glass transition temperature.

Poly(lactic acid) (PLA) copolymers having a significantly higher glass transition temperature (T(g)) than that of high molar mass PLA homopolymers (typically 60 +/- 5 degrees C) were prepared. Lactic acid was copolymerized with 1,4:3,6-dianhydro-D-glucitol (isosorbide, ISB) and succinic acid (SA-2), 1,2,3,4-butanetetracarboxylic acid (BTCA-4) or 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (HCA-6). The highest T(g)s obtained for the copolymers containing BTCA-4 and HCA-6 were 80 and 86 degrees C, respectively.

Polylactide stereocomplexation leads to higher hydrolytic stability but more acidic hydrolysis product pattern.

Poly-l-lactide/poly-d-lactide (PLLA/PDLA) stereocomplex had much higher hydrolytic stability compared to plain PLLA, but at the same time shorter and more acidic degradation products were formed. Both materials were subjected to hydrolytic degradation in water and in phosphate buffer at 37 and 60 degrees C, and the degradation processes were monitored by following mass loss, water uptake, thermal properties, surface changes, and pH of the aging medium. The degradation product patterns were determined by electrospray ionization-mass spectrometry (ESI-MS).