Poly(β-cyclodextrin)-mediated polylactide-cholesterol stereocomplex micelles for controlled drug delivery

Abstract

A series of host-guest interaction-adjusted polylactide stereocomplex micelles was prepared via the self-assembly of 4-armed poly(ethylene glycol)-block-poly(L-lactide/D-lactide)-cholesterol (4-armed PEG-b-PLLA/PDLA-CHOL) and poly(β-cyclodextrin) (PCD) with the molar ratios of CHOL/β-CD at 1 : 0.5, 1 : 1, and 1 : 2 in an aqueous environment. The hydrodynamic diameters of the micelles ranged from 84.1 nm to 107 nm depending on the molar ratio of CHOL/β-CD. It was shown that the micelle with the largest proportion of PCD possessed excellent abilities in drug release, cell internalization as well as proliferation inhibitory effect toward human A549 lung cancer cells. The results demonstrated that the stereocomplex and host-guest interactions-mediated PLA micelles exhibited great potential in sustained drug delivery.In recent years, self-assembled polyester micelles have attracted a great deal of attention in the application for drug delivery, mainly due to its optimal biodegradability and biocompatibility [1,2] . Hydrophilic poly(ethylene glycol) (PEG) and hydrophobic polylactide (PLA) are universally used components in block copolymers, and such copolymers have shown distinctive properties in multiple studies [3,4] . Poly(L-lactide) (PLLA) and poly(Dlactide) (PDLA) are two stereoisomeric structures of PLA. In more recent studies, PEG-PLLA and PEG-PDLA copolymers were blended into stereocomplex systems of PEG-PLLA/PDLA [5,6] . It was reported that compared with isotactic polymers, the constructed stereocomplex micelles showed enhanced kinetic stability [7] , higher drug loading efficiency [8] , and more sustained drug release [9] .Cyclodextrins (CDs) are a kind of macrocyclic oligosaccharides consisting of six to eight α-Dglucopyranoside units in a ring linked by α-1,4-glycosidic bond. CDs feature distinctive construction where all polar groups are located at the surface, forming a relatively nonpolar cavity to combine various lipophilic guest molecules [10,11] , including adamantane (ADA), cholesterol (CHOL), and aromatic compounds, etc. Therefore, CDs hold enormous potential in forming host-guest inclusion systems for drug delivery. As a member of CDs whose application has been approved by the US Food and Drug Administration (FDA), β-CD is made up of seven glucopyranoside monomers and has gained wide attention due to its inclusion formation capability, along

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Encapsulation of hydrophobic vitamins by polylactide stereocomplexation and their release study

“…In the case of high molecular weight PLA, the stereocomplex melting point is about 50 °C higher (230 °C) than that of the PLLA or PDLA homopolymers (180 °C), and the melting enthalpy value reported in the literature (reflecting polymer crystallinity) for 100% crystalline stereocomplex prepared from high molecular weight PLA is 142 J g −1 (145 J g −1 by other authors) whereas one of the reported melting enthalpies of PLLA homocrystallites is 93 J g −1 . The stabilization of PLA‐based micelles (PLA/poly(ethylene oxide) or PLA with other hydrophilic block copolymers) by the introduction of PLA stereocomplex into the micelle structure has been applied by many authors and this type of stereocomplex implementation dominates . Apart from micelles formed in a water medium, different solid (nano)microparticles based on PLLA and PDLA copolymers were also prepared by the application of such methods as solvent evaporation, precipitation, lowering solvent temperature or spray droplet atomization .…”