No abstract

Viewing from the material design perspective, the sophistication of nature in generating materials with great precision provides opportunities to learn from in order to achieve the controlled generation of functional materials with well-defined architectures, ordered periodicity, and stability. Inspired by the two-dimensionality and surface chemistry of red blood cells and blood platelets, we attempted to implement the forces induced by crystallization and phase separation of amphiphilic carbohydrate-based crystalline-coil block copolymers to induce self-assembly generating two-dimensional (2D) lamellar platelet structures. With the current generation of functional 2D platelet structures via crystallization-driven self-assembly (CDSA) of block copolymers, transitioning the existing system into a biocompatible and bioactive system is mandatory in order to bring their functionality and applicability to another level. In this study, we introduce the crystallization-driven self-assembly of d-fructose-functionalized crystalline-coil block copolymers featuring poly­(ε-caprolactone) as the crystallizable core-forming block. By fine-tuning the corona length and composition, we obtained 2D platelets ranging in the scale between nanometer (183 nm, length) to micrometer size range (2–4 μm, length), with the latter featuring intrinsically highly ordered core-crystalline structure of orthorhombic single crystals as observed by the means of electron microscopy techniques and selected-area electron diffraction (SAED) experiment. We discovered the platelet structures to grow epitaxially through the addition of free polymer, forming supersized hexagonal 2D platelets (ca. 19–21 μm), in a process akin to the growth of living polymers. The seeded growth of these platelets suggests a memory effect, providing a platform for further hierarchical self-assembly and functionalization. The overall approach presents a facile strategy in fabricating the increasingly important colloidally stable bioinspired 2D structures with characteristic features and functional properties.

Self-assembled block copolymer (BCP) nanoparticles offer exciting opportunities for drug delivery applications. A key feature of using BCP nanoparticles for drug delivery is their ability to accommodate therapeutic cargoes within their particle core. This has become widely established for BCP nanoparticles with an amorphous core. The same, however, cannot be achieved with BCP nanoparticles with a crystalline core. This is because the encapsulation of therapeutic cargoes in a crystalline particle core disrupts crystallinity and ultimately leads to particle disassembly. Herein, we present several strategies to incorporate therapeutics and other functional cargoes onto the surface of crystalline particles, as this helps to ensure that the crystallinity of the particle core is maintained and the particle morphology is hence unaffected. As a platform to showcase our strategies, in this study, we used biodegradable and bioactive 2D glycoplatelets prepared by living crystallization-driven self-assembly (CDSA). Specifically, we show that we can incorporate either an anticancer drug, doxorubicin (DOX), or a fluorescent dye, Cyanine5 (Cy5), onto the surface of glycoplatelets by seeded growth of prefunctionalized polymers or via postmodification using polymers with reactive handles. We believe that the strategies presented herein are versatile and should thus be applicable to other CDSA systems. Overall, our findings present new opportunities for crystalline particles to be used in drug delivery application.

A critical challenge in the application of functional cellulose fibrils is to perform efficient surface modification without disrupting the original properties. Three-component Passerini reaction (Passerini 3-CR) is regarded as an effective functionalization approach which can be carried out under mild and fast reaction condition. In this study, we investigated the application of Passerini 3-CR for the synthesis of thermoresponsive cellulose fibrils by covalently tethering poly­(N-isopropylacrylamide) in aqueous condition at ambient temperature. The three components, a TEMPO-oxidized cellulose nanofiber bearing carboxylic acid moieties (TOCN-COOH), a functionalized polymer with aldehyde group (pNIPAm-COH) and a cyclohexyl isocyanide, were reacted in one pot resulting in 36% of grafting efficiency within 30 min. The chemical coupling was evidenced by improved aqueous dispersibility, which was further confirmed by FT-IR, TGA, UV–vis, and turbidity study. It was observed that the grafting efficiency is strongly dependent on the chain length of the polymer. Furthermore, AFM and X-ray diffraction measurements affirmed the suitability of the proposed method for chemical modification of cellulose nanofibers without significantly compromising the original morphology and structural integrity.