Programmed Degradation of Hydrogels with a Double‐Locked Domain

Abstract

The ability to control the degradation of a material is critical to various applications. The purpose of this study was to demonstrate a concept of controlling degradation by using a double‐locked domain (DLD). DLDs are molecular structures with two functional units that work cooperatively under environmental stimulation. One unit is triggered to transform without cleavage in the presence of the first stimulus, but this transformation enables the activation of the other unit for cleavage in the presence of the second stimulus. A DLD is presented that is activated to transform through intramolecular reconfiguration when exposed to light. After this transformation, the light‐triggered DLD can undergo rapid cleavage under acid treatment. When this DLD is used as the crosslinkers of hydrogels, hydrogels undergo rapid degradation after sequential exposure to light irradiation and acid treatment. Reversing the order of light irradiation and acid treatment or only using individual stimulation does not lead to comparable degradation. Thus, this study has successfully demonstrated the great potential of using DLDs to achieve programmable degradation of materials.

Thermoresponsive Hydrogels as Microniches for Growth and Controlled Release of Induced Pluripotent Stem Cells

“…[ 61 ] To achieve of hydrogel degradation, different strategies for cleaving chemical bonds in the hydrogels networks have been applied. For example, photolytic, [ 62 ] hydrolytic, [ 63 ] enzymatic degradation, [ 35 ] and hydrolysis under acidic pH [ 63 ] have a great potential for degradation mechanisms which have been tried for controlled release applications. [ 41 ] However, for these strategies, the photo energy, the hydrolytic initiator, enzyme, and the acidic pH environment would inevitably damage the viability of the cells and might also lead to cell differentiation.…”

Supramolecular Adhesive Hydrogels for Tissue Engineering Applications

“…The degradability of supramolecular adhesive hydrogels is also an important design parameter during tissue engineering applications. , For instance, degradation can provide space for proliferating cells and allow ingrowth of bone during bone regeneration applications . When supramolecular adhesive hydrogels are applied for wound dressing, the degradation of gels can allow the infiltration of blood vessels and enable gels to be painlessly removed .…”

Transient Photodegradability of Photostable Gel Induced by Simultaneous Treatment with Acid and UV–Light for Phototuning of Optically Functional Materials

“…This is in stark contrast to conventional materials, which initially undergo an irreversible photoreaction process and then photodegrade in the presence of chemical additives. [29,30]…”

“…Accordingly, based on the abovementioned analyses for the reaction products, UV-irradiation to Pt-EB with and b) previous approaches to control the photodegradability of materials with cross-linkers. [29,30] HCl triggered the PtC bond cleavage through different reaction mechanisms of the platinum-acetylide complex with only HCl, wherein the former facilitated chloroacetylene moiety whereas the latter provided terminal alkyne moiety. The different mechanisms enabled a unique relationship of reactivity as shown in the Venn diagram in Figure 1c, which represents switching between photoreactivity and photostability in materials.…”