RESUMO
Two photoswitchable arylazopyrozoles form hydrogels at a concentration of 1.2 % (w/v). With a molecular weight of 258.28â g mol-1 , these are the lowest known molecular weight hydrogelators that respond reversibly to light. Photoswitching of the E- to the Z-form by exposure to 365â nm light results in a macroscopic gelâsol transition; nearly an order of magnitude reduction in the measured elastic and loss moduli. In the case of the meta-arylazopyrozole, cryogenic transmission electron microscopy suggests that the 29±7â nm wide sheets in the E-gel state narrow to 13±2â nm upon photoswitching to the predominantly Z-solution state. Photoswitching for meta-arylazopyrozole is reversible through cycles of 365â nm and 520â nm excitation with little fatigue. The release of a rhodamineâ B dye encapsulated in gels formed by the arylazopyrozoles is accelerated more than 20-fold upon photoswitching with 365â nm light, demonstrating these materials are suitable for light-controlled cargo release.
RESUMO
Laboratory models of the tumor microenvironment require control of mechanical and biochemical properties to ensure accurate mimicry of patient disease. In contrast to pure natural or synthetic materials, hybrid approaches that pair recombinant protein fragments with synthetic scaffolding show many advantages. Here we demonstrate production of a recombinant bacterial collagen-like protein (CLP) for thiol-ene pairing to norbornene functionalized hyaluronic acid (NorHA). The resultant hydrogel material shows an adjustable modulus with evidence for strain-stiffening behavior that resembles natural tumor matrices. Cysteine terminated peptide binding motifs are incorporated to adjust the cell-adhesion points. The modular hybrid gel shows good biocompatibility and was demonstrated to control cell adhesion, proliferation, and the invasive properties of MCF7 and MD-MBA-231 breast adenocarcinoma cells. The ease in which multiple structural and bioactive components can be integrated provides a robust framework to form models of the tumor microenvironment for fundamental studies and drug development.