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Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers
Published on: June 20, 2019
Time-Resolved Small-Angle X-ray Scattering Studies of pH-Induced PMPC-PDPA Diblock Copolymer Self-Assembly
Guoxing Liao1, Daniel T W Toolan2, Nicholas J Warren3
1South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, Guangdong Basic Research Center of Excellence for Energy and Information Polymer Materials, South China University of Technology, Guangzhou 510640, China.
Abstract:
Despite the potential of poly(2-methacryloyloxy ethyl phosphorylcholine)-poly(2-(diisopropylamino)ethyl methacrylate) (PMPC-PDPA) diblock copolymer nanoparticles for several biological applications, the exact mechanism of pH-induced self-assembly of the PMPC-PDPA chains into nanoparticles remains unclear, although it has been extensively studied by ex situ transmission electron microscopy. Here, we probe this process using time-resolved small-angle X-ray scattering (TR-SAXS) to gain an understanding of the phenomena that occur on the nanoscale. Modeling the TR-SAXS data indicated that spherical micelles and vesicles were formed at a pH as low as 3, and the spherical micelle and vesicle structures reformed at pH 5.5. At pH ∼5.5, insoluble PMPC25-PDPA70 diblock copolymer precipitation was also observed by SAXS. A huge soluble PMPC25-PDPA70 diblock copolymer reservoir might assist in PMPC25-PDPA70 vesicle construction. Additionally, a potential pathway of vesicle construction by spherical micelle fusion was supported by the SAXS evidence.
