Precise Control of Two-Dimensional Platelet Micelles from Biodegradable Poly(p-dioxanone) Block Copolymers by Crystallization-Driven Self-Assembly

Abstract

Two-dimensional (2D) core–shell nanoparticles have been attracting increasing interest due to their wide applications in materials science. Living crystallization-driven self-assembly (CDSA) is an ambient temperature, seeded growth method of crystallizable block copolymers (BCPs) in selective solvents, which has been demonstrated to be a powerful tool for the creation of one-dimensional (1D)/2D nanomaterials with precise control over size and compositions. Nevertheless, the development of an efficient living CDSA approach is a challenge for the case of semicrystalline poly­(p-dioxanone) (PPDO) as a core-forming block, where the dimensional control is poor. Herein, we demonstrate that the insufficient size control of 2D PPDO platelets could be overcome through modulation of solvent compositions or elevating the crystallization temperatures for PPDO. The possible mechanism involves an improved unimer solubility that avoids fast unimer aggregation. As a result, uniform 2D platelet micelles with a controlled area over a substantial size range are created via epitaxial growth of the unimer. It is noteworthy that the shape control of 2D platelet micelles from quasi-square to elongated hexagon to lozenge shapes can be accessible by regulating the crystallization conditions such as adding different amounts of cosolvents or crystallization at an elevated temperature. Meanwhile, spatially defined block comicelles can be achieved via the seeded growth approach from PPDO core-forming BCPs with different corona functionalities at elevated temperatures. The excellent water stability and biocompatibility properties of 2D PPDO platelet micelles further enable them to have a potential application as cargo vehicles in the drug delivery field.

Seeded Epitaxial Growth of Crystallizable Polymers Governed by Crystallization Temperatures

“…Crystallization-driven self-assembly (CDSA) of block copolymers (BCPs) with a crystallizable segment is a powerful tool used to create anisotropic polymer nanoparticles with precision control over size, shape, and compositions. − One-dimensional (1D) − and two-dimensional (2D) − precision polymer nanoparticles are extensively fabricated by using this approach. Living CDSA is a seeded growth approach of increasing importance for the creation of 1D/2D core–shell materials with enhanced complex structures from crystallizable BCPs. − In a seeded growth method, the crystallization process of nucleation and crystal growth is divided into two separated steps, i.e., the first step of preparation of crystalline seeds and the second step of crystal growth.…”

Scalable and Uniform Length-Tunable Biodegradable Block Copolymer Nanofibers with a Polycarbonate Core via Living Polymerization-Induced Crystallization-Driven Self-assembly

“…Living CDSA ,− has been employed for a variety of amphiphilic BCPs with crystallizable core-forming segments such as poly­(ferrocenyldimethylsilane) (PFS), , polyethylene, , poly­( l -lactide) (PLLA), ,, and poly­(3-hexylthiophene). ,, More recent work has focused on examples of interest for biomedical applications such as polycaprolactone, , poly­(isopropyloxazoline) , poly­(fluorenetrimethylenecarbonate) (PFTMC), , and poly­( p -dioxanone), in addition to biopolymer-based building blocks that include polypeptides, DNA–polymer hybrids, and collagen triple helices . 1D micelles containing a well-characterized crystalline PFTMC core segment are of significant interest for biomedical applications due to their biocompatibility, biodegradability, and lack of cytotoxicity. ,− Recently, we illustrated the potential use of uniform 1D PFTMC-based nanofibers as drug delivery vehicles by demonstrating their loading with hydrophobic cargo .…”

Uniform Two-Dimensional Crystalline Platelets with Tailored Compositions for pH Stimulus-Responsive Drug Release

“…29−31 A seeded growth approach, termed as "living" CDSA, further facilitated the formation of 2D complex block coplatelets with spatially defined compositions and functionalities from crystallizable BCPs or polymer blend combinations. 32−35 Up to now, living CDSA of crystallizable polymers has been extended to the biocompatible and biodegradable semicrystalline polymers, such as poly(εcaprolactone) (PCL), 33,36−40 poly(L-lactic acid) (PLLA), 41−44 poly(p-dioxanone) (PPDO), 32 and polycarbonate (PC). 14,45,46 The 1D or 2D CDSA nanoassemblies led to intense interest in the biomedical applications, especially for drug delivery fields.…”

“…In past decades, crystallization-driven self-assembly (CDSA) of crystallizable BCPs has attracted increasing attention owing to the abilities in formation of anisotropic one-dimensional (1D) − and two-dimensional (2D) − nanoparticles with precision control over size and shape. The CDSA approach is extensively applied to the poly­(ferrocenyldimethylsilane) (PFS) core-forming BCPs, and many state-of-the-art assemblies are fabricated by Manners. − A seeded growth approach, termed as “living” CDSA, further facilitated the formation of 2D complex block coplatelets with spatially defined compositions and functionalities from crystallizable BCPs or polymer blend combinations. − Up to now, living CDSA of crystallizable polymers has been extended to the biocompatible and biodegradable semicrystalline polymers, such as poly­(ε-caprolactone) (PCL), ,− poly­( l -lactic acid) (PLLA), − poly­( p -dioxanone) (PPDO), and polycarbonate (PC). ,, The 1D or 2D CDSA nanoassemblies led to intense interest in the biomedical applications, especially for drug delivery fields. ,, …”