Customizing the Hydrolytic Degradation Rate of Stereocomplex PLA through Different PDLA Architectures

Abstract

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. Stereocomplexes containing star shaped D-LA oligomers with four alcoholic end-groups underwent a rather slow hydrolytic degradation with low release of degradation products. Materials with linear D-LA oligomers exhibited similar mass loss but released higher concentrations of shorter acidic degradation products. Increasing the fraction of D-LA oligomers with a linear structure or with four alcoholic end-groups resulted in slower mass loss due to higher degree of stereocomplexation. The opposite results were obtained after addition of D-LA oligomers with carboxylic chain-ends. These materials demonstrated lower degree of stereocomplexation and larger mass and molar mass loss, and also the release of degradation products increased. Increasing the number of alcoholic chain-ends from four to six decreased the degree of stereocomplexation, leading to faster mass loss. The degree of stereocomplexation and degradation rate were customized by changing the architecture and end-groups of the D-LA oligomers.

Configurational Molecular Glue: One Optically Active Polymer Attracts Two Oppositely Configured Optically Active Polymers

“…In the case of PLA, the mechanical performance, thermal/hydrolytic degradation-resistance of stereocomplexed materials are higher than those of constituent polymers, L-PLA and D-PLA11121314151617. A variety of stereo block343536373839404142434445464748495051, star-shaped5253545556575859606162636465, star-shaped stereo block PLAs6667686970 were synthesized, and the effects of stereo block and star-shaped or branching architectures on crystallization were extensively investigated and found to have crucial effects on stereocomplex (SC) and homo-crystallization behavior.…”

Novel Polymeric Nanoparticles for Intracellular Delivery of Peptide Cargos: Antitumor Efficacy of the BCL-2 Conversion Peptide NuBCP-9

“…S2A and B). At pH 5.0, PLA chains remain in a coiled state and are thereby less susceptible to hydrolytic degradation (26, 27). By contrast, at pH 7.4, the PLA chains uncoil due to ionization, which is associated with an increase in NP degradation and release of NuBCP-9.…”

“…At pH 5.0, PLA remains coiled and is less susceptible to hydrolysis; whereas at pH 7.4, the PLA chains open with an increased propensity for hydrolysis. The uncoiling of PLA is thus associated with an increase in its degradation and release of NuBCP-9 (26, 27). These findings collectively indicate that peptide release from polymeric NPs can be controlled by varying the sizes of the PEG and PLA blocks.…”

Tuning the Degradation Profiles of Poly(l-lactide)-Based Materials through Miscibility

“…Tailoring the degradation rate of poly( l -lactide) (PLLA) has been addressed using several techniques, including copolymerization, 1−3 plasticization, 4,5 stereocomplexation, 6−8 blending, 9,10 and surface modification. 11,12 These approaches are generally designed to accelerate the degradation rate of PLLA; however, despite their effectiveness, they suffer from some inherent drawbacks.…”