Responsiveness and Morphology Study of Dual Stimuli‐Controlled Supramolecular Polymer

Wholly Visible-Light-Responsive Host-Guest Supramolecular Gels Based on Methoxy Azobenzene and β-Cyclodextrin Dimers

Much attention has been paid to construct photoresponsive host-guest supramolecular gels; however, red-shifting the responsive wavelength remains a formidable challenge. Here, a wholly visible-light-responsive supramolecular gel was fabricated through the host-guest interaction between a β-cyclodextrin (β-CD) dimer and a tetra-ortho-methoxy-substituted azobenzene (mAzo) dimer (binary gelator) in DMSO/H₂O (V/V = 8/2). The minimum gelation concentration of the low-molecular-weight binary gelator was 6 wt % measured via the tube inversion method. The substituted methoxy groups shifted the responsive wavelengths of trans-mAzo and cis-mAzo to the green and blue light regions, respectively. The host-guest interaction between mAzo and β-CD as the driving force for gelation was confirmed using the ¹H-NMR and 2D ¹H NOESY spectra. The supramolecular gel showed good self-supporting ability with a storage modulus higher than 10⁴ Pa. The release of Rhodamine B loaded in the gel as a model drug could be controlled by green light irradiation. We envisioned the potential applications of the wholly visible-light-responsive supramolecular compounds ranging from biomedical materials to smart materials.

Microphase separation of a quadruple hydrogen bonding supramolecular polymer: effect of the steric hindrance of the ureido-pyrimidone on their viscoelasticity

Supramolecular polymers based on 2-ureido-4[1H]-pyrimidone (UPy) units with extremely high dimerization constants and adjustable properties have received significant attention. In this work, we attempt to discuss the relationship between the micro-phase separation and the viscoelastic properties of the supramolecular polymers. For this reason, polymers with different UPy moieties structures and different UPy moieties contents were prepared and studied. It was found that the UPy moiety with little hindrance at the six-position of the pyrimidone could self-assemble into a nano-fiber structure and the degree of the micro-phase separation increased with the content of the UPy moiety. With the enlargement of the steric hindrance of the six-position of the pyrimidone, the nano-fiber structure gradually disappeared, meaning the degree of the micro-phase separation decreased astonishingly. More importantly, with the degree of the micro-phase separation increased, the storage modulus or the elasticity modulus increased exponentially and the T m and the loss modulus area increased linearly. These results would lead a new way to study and develop novel polymeric materials.

Targeted and Sustained Corelease of Chemotherapeutics and Gene by Injectable Supramolecular Hydrogel for Drug-Resistant Cancer Therapy

Coadministration of chemotherapeutics as well as therapeutic gene could play a synergistic effect on cancer treatment. It is noteworthy that targeted and sustained codelivery of chemotherapeutic and therapeutic gene was rarely achieved in previous reports, while it might serve as an important platform for treating solid tumor with possible surrounding lesions. Herein, an injectable supramolecular hydrogel formed by α-cyclodextrin (α-CD) and cationic amphiphilic copolymer made of methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly(ethylene imine) with folic acid targeted group (MPEG-PCL-PEI-FA), is rationally designed to achieve sustained codelivery of chemotherapeutic paclitaxel (PTX) and B-cell lymphoma-2 (Bcl-2) conversion gene Nur77 in the form of nanocomplex up to 7 days, to effectively inhibit the growth of folate receptor overexpressing H460/Bcl-2 therapeutic-resistant tumors (induced by overexpression of anti-apoptotic Bcl-2 protein), with peritumoral injection rather than direct intratumoral injection of hydrogel. To the best of our knowledge, this is a pioneer report on injectable MPEG-PCL-PEI-FA/α-CD supramolecular hydrogel with the ability to codeliver and sustainedly release PTX and Nur77 gene to combat Bcl-2 overexpressed therapeutic-resistant tumors in a targeted manner, which might be beneficial for further design in personalized medicine.