Self-Healing and Injectable Shear Thinning Hydrogels Based on Dynamic Oxaborole-Diol Covalent Cross-Linking

Abstract

Hydrogels containing sugar and oxaborole residues with remarkable self-healing properties were synthesized by free-radical polymerization in a facile and one pot process. The strong covalent interactions between the oxaborole residues and free adjacent hydroxyl groups of the pendent sugar residues of the glycopolymer allowed the in situ formation of hydrogels achievable under either neutral or alkaline conditions. These hydrogels showed excellent self-healing and injectability behaviors in aqueous conditions and were found to be responsive to both pH and the presence of free sugars (such as glucose) in solution. Furthermore, these hydrogels can easily be reconstructed from their lyophilized powder into any desired three-dimensional scaffold. Additionally, the hydrogels can be designed to have very low cytotoxicity and hence can be used as a scaffold for cell encapsulation. With these unique properties, these biocompatible, biodegradable, rebuildable, and self-healable hydrogels offer great potential in many biomedical applications.

Structurally Tunable pH-responsive Phosphine Oxide Based Gels by Facile Synthesis Strategy

“…[30][31][32][33][34][35][36] Additionally, gels prepared by these means also involve multiple steps of post-modification and purification. 19,[37][38][39][40][41] Developing gelators with site-specific reactivity is essential to eliminate multiple intermediate steps and achieve cleaner gels. The nanoscale architectural features, e.g., the chain configurations and network homogeneity, induce varying diffusion rates for the loaded drugs in gels.…”

Self-crosslinking smart hydrogels through direct complexation between benzoxaborole derivatives and diols from hyaluronic acid

“…Among polymeric assemblies, hydrogels crosslinked through boronate-diol complexes have emerged as promising injectable materials for drug delivery and tissue engineering mainly because of their self-healing ability. [3][4][5][6][7] This property is related to the dynamic covalent nature of these bonds allowing hydrogels to reconfigure their covalent structure, and thereby to self-repair without any external stimuli after rupture. [8][9][10] In these hydrogels, the formation of boronate ester crosslinks depends on the binding affinity (K a ) of the boronic acid derivative for a given diol or polyol, which is influenced by the pH of the medium, and the pK a of the small molecular partners.…”

Biologically Inspired and Chemically Derived Methods for Glucose‐Responsive Insulin Therapy

“…The cross‐links themselves are typically boronate esters that arise from simultaneous conjugation of covalently presented diol‐bearing moieties and PBAs. This approach can be accomplished through the inclusion of both subunits as pendant groups on the same polymer or by functional attachments to separate polymers that are then mixed . Phenylboronic esters, a class of PBA derivatives, are known to demonstrate peroxide‐sensitive degradation behavior, and have been exploited in some systems to drive insulin release dependent on the H 2 O 2 generated from GOx activity or from other sources .…”