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Polylactide (PLA, two enantiomers: PLLA and PDLA) is well-known for its biocompatibility, biodegradability, and good mechanical capacity. However, PLLA and PDLA have been rarely explored in spite of the well-known significance of chirality and chiral (macro)molecules. This work aims to investigate PLLA and PDLA’s chirality in terms of enantioselectivity towards chiral guests. For this purpose, PLA-based chiral particles were successfully prepared and demonstrated enantioselectivity in releasing chiral drug, naproxen. The PLLA- and PDLA-based particles both showed enantioselectivity towards the chiral drug, i.e. preferably releasing S-naproxen over the R-enantiomer. Moreover, PDLA-based particles showed enantioselectivity only in racemic release mode but not in single enantiomer release mode. We accordingly propose that enantio-differentiating effects not only occur in release process, but also in drug loading process. The intriguing findings are essentially different from other chiral polymers investigated earlier, and deserve much more interest due to the extensive uses of PLA as biomaterials.

A judicious combination of chiral structure with other functionalities in one entity may provide novel materials. For this purpose, boronic acid functional group was integrated with optically active helical substituted polyacetylene microspheres. To prepare the designed functional microspheres, two substituted acetylene monomers, i.e. chiral monomer M1 and achiral monomer M2 which was prepared from a boronic acid derivative, were synthesized and copolymerized through suspension polymerization for constructing polymeric microspheres. SEM images demonstrated the successful formation of the microspheres. X-ray photoelectron spectroscopy was measured to determine boronic acid content on the surface of the as-prepared microspheres. Circular dichroism spectra showed that one-handed helices were formed in the copolymer chains constructing the microspheres, which enabled the microspheres to exhibit enantio-differentiating adsorption capacity towards 3,4-dihydroxy-l-phenylalanine (l-DOPA), whereas 3,4-dihydroxy-d-phenylalanine (d-DOPA) was preferentially released. Amazing synergistic effects occurred in the helical polymer chains and the pendant boronic acid moieties. Desorption capacity and recyclability of the microspheres were also clearly verified. The unprecedented optically active microspheres hold practical applications for developing materials used for chiral adsorption, enantiomeric drug controlled release, etc.