Synthesis of 4-PEG-imidazole 4-PEG-imidazole was synthesized following modifications to the method in the reference. 1 g of 4-arm 10 kDa PEG-NH2, 0.23 g of 3-(N-1-Trityl-imidazoleazol-4-yl)propionic acid, 0.32 g of BOP were dissolved in 10 mL of DMF in a Schlenk flask under continuous nitrogen flow. 0.21 mL of DIPEA was added to begin the reaction under magnetic stirring, which ran overnight under N2. The product was precipitated in 50 mL of ether, purified in 10 mL of methanol three times (by dissolving in methanol, precipitating the product in the freezer, and then separating the supernatant via centrifugation), and precipitated again in 40 mL of ether. 95 mL of TFA, 2.5 mL of TIPS, and 2.5 mL of H2O, were added to the solid product and the solution was left under magnetic stirring for 2 h. 100 mL of methanol was added, and the solvent was removed using a roto-vap. The solid product was precipitated in 10 mL of methanol, and 50 mL of ether three times, after which the final product was vacuum dried. The final product is a white solid, with the imidazole residue exhibiting 1 H-NMR peaks (500 MHz, CDCl3) at ca. 8.61 and 7.76, allowing us to calculate the average coupling efficiency of 78%.