Non-cytotoxic Dityrosine Photocrosslinked Polymeric Materials With Targeted Elastic Moduli

Abstract

Controlling mechanical properties of polymeric biomaterials, including the elastic modulus, is critical to direct cell behavior, such as proliferation and differentiation. Dityrosine photocrosslinking is an attractive and simple method to prepare materials that exhibit a wide range of elastic moduli by rapidly crosslinking tyrosyl-containing polymers. However, high concentrations of commonly used oxidative crosslinking reagents, such as ruthenium-based photoinitiators and persulfates, present cytotoxicity concerns. We found the elastic moduli of materials prepared by crosslinking an artificial protein with tightly controlled tyrosine molarity can be modulated up to 40 kPa by adjusting photoinitiator and persulfate concentrations. Formulations with various concentrations of the crosslinking reagents were able to target a similar material elastic modulus, but excess unreacted persulfate resulted in cytotoxic materials. Therefore, we identified a systematic method to prepare non-cytotoxic photocrosslinked polymeric materials with targeted elastic moduli for potential biomaterials applications in diverse fields, including tissue engineering and 3D bioprinting.

Non-Covalently Associated Streptavidin Multi-Arm Nanohubs Exhibit Mechanical and Thermal Stability in Protein-Network Materials

“…To confirm whether any SAv-SAv crosslinking affects the interfaces of SAv tetramers, we prepared the hydrogel with the reduced reagent concentration to 31µM ruthenium and 15mM ammonium persulfate which minimized unspecific crosslinking between SAv tetramers (Figure S4). While the reduced concentration impacted the G′ as expected based on our previous report on ELP gels, 55 crossover frequency was not still observed (Figure 5d). Therefore, we concluded that, due to the high mechanical stability, the specifically self-associated, tetra-SAv in protein-network hydrogel behaves like a chemical cross-linker despite the fact that tetra-SAv is formed from non-covalent interactions.…”

“…54 In our previous study, we used ELP with controlled numbers of tyrosine residues to modulate mechanical properties in photo-crosslinked protein-network materials. 55 We adapted the ELP sequence and further engineered to prepare A 2 YA 2 -A 48 -SAv artificial proteins ( Figure 5a ), where A and Y represent the five amino acid sequence, VPGXG with either alanine (A) and tyrosine (Y) in the X position, respectively. Therefore, offering only one site of photo-crosslinking at the end of each ELP arm, which is at the opposite terminus to the SAv physical cross-linkers (Figure 5a; Table S1).…”

“…A 2 YA 2 -A 48 -SAv was purified using inverse transition cycling (ITC), exploiting the lower critical solution temperature (LCST) of elastin-like polypeptides. 54, 55 After 4 cycles of ITC purification 55 , samples were dialyzed in deionized water to remove all salt impurities. All purified protein samples were flash frozen using liquid nitrogen, lyophilized, and stored at - 20°C.…”

Photochemical and Electrochemical Applications of Proton-Coupled Electron Transfer in Organic Synthesis

“…The employment of this photo-cross-linking reaction to improve the material properties of other tyrosine-containing hydrogels was also reported. 1070 − 1073 …”

Rapid and cytocompatible cell-laden silk hydrogel formation via riboflavin-mediated crosslinking

“…Riboflavin (RB), also known as vitamin B2, is a non-toxic photoinitiator recently used for the preparation of silk fibroin hydrogels upon exposure to visible light. 7 A main limitation for the use of RB, however, is the slow gelation kinetics, 7,23,24 which would make this RB-based crosslinking not suitable for the encapsulation of cells within the hydrogel matrix. Here, we propose a method to achieve a fast and cytocompatible gelation of silk fibroin via RB-mediated crosslinking.…”