Polyelectrolyte complex scaffoldings for photocrosslinked hydrogels

Abstract

Photocrosslinkable precursors (small molecules or polymers) undergo rapid crosslinking upon photoirradiation, forming covalently crosslinked hydrogels. The spatiotemporally controlled crosslinking, which can be achieved in situ, encourages the utility of photocrosslinked...

Advances, Applications, and Emerging Opportunities in Electrostatic Hydrogels

“…For instance, BCC ordering at a polymer concentration of 12 wt% was noted by Kim et al in triblock polyelectrolyte assemblies with long charged block lengths [charged block degree of polymerization (DP) of 78 (Figure d)]. Hydrogel microstructure can also be modulated by varying extrinsic factors like salt, pH, temperature, and crowding agents. ,,, For instance, Krogstad et al , and Kim et al have presented the microstructural evolution of PEC hydrogels as a function of polymer concentration (intrinsic factor) and salt concentration (extrinsic factor), highlighting how they affect hydrogel microstructure inversely and, therefore, can be employed in tandem to modulate the microstructure.…”

“…Typical PEC hydrogels comprise a bPE as at least one of the two (or more) oppositely charged components. As such, the simplest way to create a PEC hydrogel is by mixing a triblock polyelectrolyte with an oppositely charged homopolyelectrolyte (Figure a), ,,,, diblock polyelectrolyte (Figure b), , or triblock polyelectrolyte (Figure c). ,,,,,,,,,− , It is also possible to create a PEC hydrogel by mixing a triblock polyelectrolyte with oppositely charged macroions , or multivalent metal ions (Figure d). , Hydrogels with assemblies of oppositely charged bPEs [i.e., diblock, triblock, and pentablock (Figure e)] have also been demonstrated. , Finally, in addition to linear polyelectrolytes, PEC hydrogels have also been created from oppositely charged bPEs possessing nonlinear architectures [e.g., three- and four-arm bPEs (Figure f)]. , It should be noted that these combinations are not an all-encompassing description of PEC hydrogel fabrication pathways; other combinations may exist.…”

“…The swift assembly of PEC hydrogels and their relatively slow swelling rates also enabled the utility of PEC hydrogels as protective scaffoldings in biomedical applications. Our group has also demonstrated underwater curing of photo-cross-linkable precursors enabled by PEC hydrogel scaffoldings, wherein the PEC hydrogels limit the dilution, deactivation, and dissipation of the precursors while still allowing their photo-cross-linking to process in aqueous settings (Figure a). , These features have been harnessed in a handful of successful studies demonstrating the utility of PEC hydrogels, which portend well for PEC hydrogels as multifunctional biomaterials.…”

“…(a) PEC hydrogels act as protective scaffoldings enabling underwater curing of photo-cross-linkable molecules. Reproduced with permission from ref . Institution of Chemical Engineers (IChemE) and the Royal Society of Chemistry; permission conveyed through Copyright Clearance Center, Inc. (b) PEC hydrogels comprising triblock bPEs as inks for extrusion-based 3D printing.…”

“…These benefits proliferate in hydrogels in which electrostatic interactions drive self-assembly because the long-range electrostatic interactions enable faster self-assembly and greater tunability. , Broadly speaking, electrostatic hydrogels are 3D water-laden polymer networks that are physically connected by reversible ionic interactions. Numerous approaches have been developed for the preparation of electrostatic hydrogels, from simple ionically cross-linked polyelectrolytes to more intricate assemblies of block polyelectrolytes, ,,,,,,,,− macroions, multivalent coordinating ions/metals, and charged surfactants (Figure ). …”