Transiently malleable multi-healable hydrogel nanocomposites based on responsive boronic acid copolymers

Abstract

The design of materials that mimic aspects of self-healing, as observed in nature, is of paramount importance as they could solve a number of problems in the biomedical field, such as the elimination of (bio-) material failure after prolonged use, improved integration at the interface with living tissues and more robust biomechanical performance. In this report, we propose the fabrication of soft hydrogels comprising a polymer matrix of poly(vinyl alcohol) mixed with a thermoresponsive boronic acid copolymer that is subsequently impregnated with poly(vinyl pyrrolidone) coated gold nanoparticles. The gels are crosslinked by the formation of reversible boronate ester bonds that can be remotely disrupted by a thermal or optical stimulus, endowing the gels with thermally-induced transient malleability that is optically trackable. It is demonstrated that the gels exhibit excellent healing properties within minutes even without the application of external stimuli. The rapid formation of the gels in concert with their fast and mild gel-sol phase transition under biologically relevant conditions is demonstrated by the encapsulation and release of cells in vitro. The proposed materials constitute a versatile cytocompatible platform for the construction of remotely healable soft gels for biomedical applications.

Cell membrane engineering with synthetic materials: Applications in cell spheroids, cellular glues and microtissue formation

“…In Our group also reported the formation of macroscopic cell-laden gels, using a boronic acid-based copolymer and a thermoresponsive succinimide-based copolymer, under physiological conditions within seconds [119,161]. The cell glues (G' ~200 Pa) could be reversibly turned to their corresponding sol state and release their cellular cargo either by the addition of glucose (that saturates and dissociates the boronic acid groups from cell-bound diols), or by lowering the temperature below the LCST (hydrophilic state of the polymer).…”

Cellulose-based self-healing hydrogel through boronic ester bonds with excellent biocompatibility and conductivity

“…As a result, boronic ester containing hydrogels always illustrate fast reversible characteristic. 37,47 It was observed although the reversible characteristic at low frequency are different, the G 0 above 1 rad s À1 became comparable no matter the compositions, proved the compositions have very important inuence on mechanical property of the hydrogel although the CMC-B(OH) 2 itself could not form hydrogel at comparable concentration.…”

“…[27][28][29][30][31] The boronic ester bond, which is formed from phenylboronic acid and hydroxyl groups, could also be used to design a variety of self-healing hydrogels. [32][33][34][35][36][37][38] Moreover, the boronic ester bond based hydrogel always show fast self-healing based on fast boronic ester exchange.…”

Conductive hydrogel composites with autonomous self-healing properties

“…It should be noted that although the optimum pH for the complexations between the phenylboronic acids and diol groups is above 8.8 (the pKa of phenylboronic acid is around 8.8), 36 the formation of boronate ester bonds still could happen under neutral pH due to some sufficient amount of ionisable boronic acid groups as well as the rich cis-diols along the PVA chains. 37,38 Within the cross-linked system, evenly dispersed SWCNTs built the conducting channels for the network, while tetrahedral boronate ester bonds were formed through reversible complexation between the phenylboronic acids and adjacent diol groups along PVA chains, therefore endowing the hydrogel with autonomous self-healing ability without any external stimuli. Indeed, SEM images (Figure 4 (c) and (d)) of the freeze-dried hydrogel samples clearly demonstrated the three dimensional interconnected network with uniformly porous microstructures, suggesting that SWNCNTs were well distributed and evenly incorporated into hydrogels.…”