Erythrocyte-Membrane-Camouflaged Nanocarriers with Tunable Paclitaxel Release Kinetics via Macromolecular Stereocomplexation

Biomimetic-cell-membrane-camouflaged polymeric nanocarriers, possessing advantages related to the functional diversity of natural cell membranes and the physicochemical tailorability of synthetic polymers, serve as promising candidates for a therapeutic platform. Herein, we report a facile approach for the fabrication of erythrocyte (red blood cell, RBC)-membrane-camouflaged nanocarriers (RBC-MCNs) that exhibit tunable paclitaxel (PTX) release kinetics via altering macromolecular stereostructure. In this approach, biocompatible isotactic and atactic polylactides (PLAs) with similar molar masses (M_n = 8.2-8.9 kDa, as measured by NMR spectroscopy) and dispersities (&DStrok; < 1.1, as measured by size exclusion chromatography) were synthesized via organocatalyzed ring-opening polymerizations (ROPs), providing tunable crystalline structures via polymer tacticity, while RBC membranes provided biomimetic surfaces and improved colloidal stability of PLA nanoconstructs in phosphate-buffered saline (PBS, pH 7.4). Wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) analyses of the lyophilized nanoconstructs suggested significant retention of PLA stereocomplexation upon loading the hydrophobic anticancer drug PTX, enabling control over drug release kinetics. The structure-property relationships were maintained after the RBC coating, with 100% stereocomplexed PLA RBC-MCNs exhibiting the least PTX release during the first 12 h in PBS at 37 °C, compared to 2-, 3-, and 4-fold higher amounts of release for the 50% stereocomplexed, isotactic, and amorphous PLA counterparts, respectively. The extended release of PTX from the 100% stereocomplexed PLA RBC-MCNs resulted in an increased IC₅₀ (0.50 μM) against SJSA osteosarcoma cells, relative to amorphous PLA RBC-MCNs (IC₅₀ = 0.25 μM) or free PTX (IC₅₀ = 0.05 μM). In contrast, non-PTX-loaded RBC-MCNs were not cytotoxic, and they also displayed lower immunotoxic responses against RAW 264.7 macrophage cells compared to RBC membrane vesicles. This work represents fundamental advances toward a potential personalized nanocarrier technology that would be capable of employing an individual's RBCs for membrane isolation, together with tuning of cargo loading and release simply via alteration of the biocompatible PLA stereoisomer feed ratio.