Programmable Reconfiguration of Supramolecular Bottlebrush Block Copolymers: From Solution Self-Assembly to Co-Crystallization-Assistant Self-Assembly

Achieving structural reconfiguration of supramolecular bottlebrush block copolymers toward topological engineering is of particular interest but challenging. Here, we address the creation of supramolecular architectures to discover how assembled topology influences the structured aggregates, combining hydrogen-bonded (H-bonded) bottlebrush block copolymers and electrostatic interaction induced polymer/inorganic eutectics. We first design H-bonding linear-brush block copolymer P(NBDAP-co-NBC)-b-P(NBPEO), bearing linear block P(NBDAP-co-NBC) (poly(norbornene-terminated diaminopyridine-co-norbornene-terminated hexane)) with pendant H-bonding DAP (diaminopyridine) motifs, and PEO (poly(ethylene oxide)) densely grafted P(NBPEO) brush block. Thanks to H-bonding association between DAP and thymine (Thy), incorporation of Thy-functionalized polystyrene (Thy-PS65) enables solution self-assembly and formation of H-bonded bottlebrush block copolymers, generating augmented nanospheres with increasing Thy-PS65 amount. Noteworthy that integration of inorganic cluster silicotungstic acid (STA) to P(NBC-co-NBDAP)-b-P(NBPEO), endows the formation of PEO/STA eutectic core. Therefore, co-crystallization-assistant self-assembly at the interfaces of polymeric, inorganic and supramolecular chemistry is realized, reflecting multi-stage morphology transformation from hexagonal platelets, needle-like, curved rod-like micelles, finally to end-to-end closed rings, by gradually increasing Thy-PS65 while fixing STA content. Interestingly, such solution self-assembly to co-crystallization-assistant self-assembly strategy not only endows unique nanostructure transition, also induce in-to-out reconfiguration of PS domains. These findings clearly provide unique methodology towards programmable fabrication of geometrical objects promising in smart materials.

Deliver on a Promise: Hydrogen-Bonded Polymer Nanomedicine with a Precise Ratio of Chemodrug and Photosensitizer for Intelligent Cancer Therapy

The outcomes of combined cancer therapy are largely related to loading content and contribution of each therapeutic agent; however, fine-tuning the ratio of two coloaded components toward precise cancer therapy is a great challenge and still remains in its infancy. We herein develop a supramolecular polymer scaffold to optimize the coloading ratio of chemotherapeutic agent and photosensitizer through hydrogen-bonding (H-bonding) interaction, for maximizing the efficacy of intelligent cancer chemo/photodynamic therapies (CT/PDT). To do so, we first synthesize a thymine (THY)-functionalized tetraphenylporphyrin photosensitizer (i.e., TTPP), featuring the same molecular configuration of H-bonding array with chemotherapeutic carmofur (e.g., 1-hexylcarbamoyl-5-fluorouracil, HCFU). Meanwhile, a six-arm star-shaped amphiphilic polymer vehicle P(DAPA-co-DPMA-co-OEGMA)6 (poly(diaminopyridine acrylamide-co-2-(diisopropylamino)ethyl methacrylate-co-oligo(ethylene glycol) monomethyl ether methacrylate)6) is prepared, bearing hydrophilic and biocompatible POEGMA segment, along with hydrophobic PDAPA and PDPMA segments, characterizing the randomly dispersed dual functionalities, i.e., heterocomplementary H-bonding DAP motifs and pH-responsive protonation DPMA content. Thanks to the identical DAP/HCFU and DAP/TTPP H-bonding association capability, the incorporation of both HCFU and TTPP to six-arm star-shaped P(DAPA-co-DPMA-co-OEGMA)6 vehicle, with an optimized coloading ratio, can be straightforwardly realized by adjusting the feeding concentrations, thus yielding the hydrogen-bonded supramolecular nanoparticles (i.e., HCFU-TTPP-SPNs), demonstrating the codelivery of two components with the promise to optimize the combined CT/PDT efficacy.

Computational and experimental studies on the micellar morphology and emission mechanisms of AIE and H-bonding fluorescent composites

In this work, we use density functional theory (DFT) calculated competitive hydrogen bonds and dissipative particle dynamics (DPD) simulated micellar structural information to uncover the CO2-expanded liquid (CXL)-aided self-assembled structure and emission mechanisms of the self-assembled fluorescent composites (SAFCs). Herein, the SAFCs are formed through the self assembly between diblock copolymer polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) blend and the dye molecule 4-(9-(2-(4-hydroxyphenyl)ethynyl)-7,10-diphenylfluoranthen-8-yl)phenol (4) in CO2-expanded toluene at 313.2 K and varied pressures. Firstly, from DPD simulation, we have demonstrated that the addition of CO2 to toluene favors both the expansion of the solvophobic P4VP phase and contraction of solvophilic PS chains, which facilitates the continuous morphological transitions of SAFCs from spherical micelles (3.0 MPa) through wormlike plus spherical micelles (4.0-4.8 MPa) to large vesicles (6.0-6.5 MPa) with pressure rise. Secondly, the DFT calculated bonding energies and IR spectra of the competitive hydrogen bonds help us to clarify the major type of hydrogen bonds determining the fluorescence (FL) performance of the SAFCs. Furthermore, we have revealed the SAFC emission mechanism via the pressure-tunable changes in the aggregation degrees and amount of hydrogen bonds involving 4 and P4VP chains. This work provides a good understanding for the morphology-property control of the self-assembled polymer composites in both microscopic and mesoscopic scales.

Assembled Morphology of Copper-Thiourea Coordination-Mediated Metallo-Supramolecular Polymers

Metallo-supramolecular polymers represent a powerful platform to construct self-assembled morphologies. Copper-thiourea (Cu-TU) coordination interactions, though have been extensively studied in small molecular system, the role of TU motifs in synthetic polymers using metal-ligand coordination to afford supramolecular aggregation and their morphology are often overlooked. Herein, an amphiphilic random copolymer, poly(oligo(ethylene glycol) ethyl acrylate-r-acylthiourea) (P(OEGEA-r-ATU)), bearing pendant TU motifs behaving as the ligand to coordinate Cu, a design characterized by core-coordinated metallo-supramolecular polymer is rationally synthesized. Indeed, rod-like nano-objects are successfully generated via the self-assembly and coordination interaction between P(OEGEA-r-ATU) and Cu. The spatial distribution of TU moieties in polymer chain, along with their Cu chelating capability, featuring the interchain coordination interaction, is tightly related to metallo-supramolecular polymer organization. The specific Cu-TU coordination interactions enable the prompted robustness and stability of soft P(OEGEA-r-ATU), induce the polymer chain configuration, which eventually furnish efficient fabrication of rod-like nano-objects via straightforward nanoprecipitation procedure. These structural motifs of copper-coordinated, rod-like nano-objects from such metallo-supramolecular polymers endow the potential therapeutic properties, such as anti-inflammatory and antitumor effects.

Core-Coordinated Elliptic Polymer Nanoparticles Loading Copper(II) and Chlorambucil for Cooperative Chemodynamic/Chemotherapy

Chemodynamic therapy (CDT) reflects an innovative cancer treatment modality; however, to enhance its relatively low therapeutic efficiency, rational combination with extra therapeutic modes is highly appreciated. Here, core-coordinated amphiphilic, elliptic polymer nanoparticles (Cu/CBL-POEGEA NPs) are constructed via the self-assembly of a glutathione (GSH)-responsive polymer-drug conjugate, bearing side-chain acylthiourea (ATU) motifs which behave as ligands capable of coordinating Cu(II), such a design is featured by combined chemo (CT)/CDT with dual GSH depletion collectively triggered by the Cu(II) reduction reaction and disulfide bond breakage. To do so, an amphiphilic random copolymer poly[oligo(ethylene glycol)ethyl acrylate-co-thiourea] [P(OEGEA-co-ATU)] is synthesized, followed by conjugation of chlorambucil (CBL) to ATU motifs linked via a disulfide bond, thus yielding the targeted P[OEGEA-co-(ATU-g-CBL)]. In such a system, hydrophilic POEGEA serves as the biocompatible section and ATU motifs coordinate Cu(II), resulting in core-coordinated elliptic Cu/CBL-POEGEA NPs. Benefitting from the GSH-induced reduction reaction, Cu(II) is converted into Cu(I) and subsequently react with endogenous H₂O₂ to create ^•OH, realizing GSH-depletion-promoted CDT. Additionally, the disulfide bond endows GSH-responsive CBL release and provokes further GSH decline, finally realizing combined CDT/CT toward enhancing antitumor outcomes, and in vitro as well as in vivo studies indeed reveal remarkable efficacy. Such a system can provide valuable advantages to create novel nanomedicines toward cascade antitumor therapy.

Hydrogen Bond-Mediated Supramolecular Polymeric Nanomedicine with pH/Light-Responsive Methotrexate Release and Synergistic Chemo-/Photothermal Therapy

Complete cancer cure and healing are still difficult, owing to its complexity and heterogeneity. Integration of supramolecular forces, for example, hydrogen bonds (H-bonds), to anti-cancer nanomedicine affords new scaffolds for biomedical material decoration, featuring the advantages of dynamic property and easier processability. Here, we target the construction of H-bond-mediated supramolecular polymer micelles, loaded with a chemotherapeutic drug along with a photothermal agent for synergistic chemo-/photothermal therapies (CT/PTT). To do so, we design and synthesize an amphiphilic ABA-type triblock copolymer, bearing H-bonding moiety (barbiturate, Ba) within the middle hydrophobic B block. The presence of pendant Ba moieties within the hydrophobic core promotes the loading capability of methotrexate (MTX) and transportation stability, benefitting from the formation of specific Ba/MTX H-bonding interactions. IR780, a photothermal agent, concomitantly encapsulated via hydrophobic interactions, facilitates the development of a synergistic CT/PTT modalities, where MTX can be released on demand owing to the dissociation of Ba/MTX H-bonding interactions induced by elevated temperature. Such H-bonding nanomedicine possesses enhanced drug loading capacity and transport performance and can also trigger stimuli-responsive drug release in the tumor zone. We believe that H-bonded nanomedicines provide a fine toolbox that is conducive to attaining biomedical requirements with remarkable values in theranostics that are highly promising in clinical applications.

Hydrogen-Bonds Mediated Nanomedicine: Design, Synthesis and Applications

Among the various challenges in medicine, diagnosis, complete cure and healing of cancers remain difficult given the heterogeneity and complexity of such disease. Differing from conventional platforms with often unsatisfactory theranostic capabilities, the contribution of supramolecular interactions, such as hydrogen-bonds (H-bonds), to cancer nanotheranostics opens new perspectives for the design of biomedical materials, exhibiting remarkable properties and easier processability. Thanks to their dynamic characteristics, a feature generally observed for non-covalent interactions, H-bonding (macro)molecules can be used as supramolecular motifs for yielding drug- and diagnostic carriers that possess attractive features, arising from the combination of assembled nanoplatforms and the responsiveness of H-bonds. Thus H-bonded nanomedicine provides a rich toolbox that is useful to fulfill biomedical needs with unique advantages in early-stage diagnosis and therapy, demonstrating the promising potential in clinical translations and applications. We here summarize the design and synthetic routes towards H-bonded nanomedicines, focus on the growing understanding of the structure-function relationship for efficient cancer treatment. We propose a guidance for designing new H-bonded intelligent theranostic agents, to inspire more successful explorations of cancer nanotheranostics and finally to promote potential clinical translations. This article is protected by copyright. All rights reserved.

Hydrogen-Bonded Supramolecular Polymer Micelles with pH/Photothermal-Responsive Carmofur Release and Combined Chemo-Photothermal Therapy

Integrating biomedical applications (e.g., drug delivery) into supramolecular chemistry is a promising strategy. This work targets the construction of hydrogen-bonded (H-bonded) supramolecular polymeric micelles loaded with chemotherapy drugs (carmofur) and...