Molecular Stereocomplexation For Enhancing the Stability of Nanoparticles Encapsulated In Polymeric Micelles for Magnetic Resonance Imaging

Document Type

Article

Publication Date

11-24-2020

School

Polymer Science and Engineering

Abstract

A generalizable approach for improving the stability of polylactide-based (PLA-based) micelles for encapsulating nanoparticles (NPs) is demonstrated, using stereocomplexation between a pair of poly (ethylene glycol)-b-poly(d-lactide)/poly(ethylene glycol)-b-poly(l-lactide) block copolymer blends. Three different superparamagnetic ferrite-based NPs with distinct nanostructures are first prepared by the high-temperature pyrolysis method, including spherical MnFe2O4, cubic MnFe2O4, and core–shell MnFe2O4@Fe3O4. The diameters of these NPs are approximately 7–10 nm as revealed by transmission electron microscopy. These hydrophobic NPs can be encapsulated within self-assembled, stereocomplexed PLA (sc-PLA) micelles. All sc-PLA micelle systems loaded with three different NPs exhibit enhanced stability at elevated temperatures (20–60 °C) and with extended storage time (∼96 h) compared with analogous samples without stereocomplex formation, confirmed by dynamic light scattering measurements. The magnetic NP-loaded micelles with mean diameters of approximately 150 nm show both biocompatibility and superparamagnetic property. Under a 1.5 T magnetic field, cubic MnFe2O4 (c-MnFe2O4)-loaded micelles exhibit an excellent negative contrast enhancement of MR signals (373 mM–1·s–1), while core–shell MnFe2O4@Fe3O4-loaded micelles show a slightly lower signal for MR imaging (275 mM–1·s–1). These results suggest the potential of using sc-PLA-based polymer micelles as universal carriers for magnetic resonance imaging contrast agents with improved stability for different applications such as cancer diagnosis.

Publication Title

Langmuir

Volume

36

Issue

46

First Page

13881

Last Page

13889

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