SHIELD was synthesized as previously reported (Cai et al. 2015 (link)). Briefly, 8-arm polyethylene glycol sulfone (PEG-VS) (MW 20 kDa) was purchased from JenKem Technology (Plano, TX) and the custom peptide P1 (sequence: EYPPYPPPPYPSGC) was purchased from Genscript Corp (Piscataway, NJ, USA). The PEG-P1 copolymer was synthesized by reacting 8-arm PEG-VS in excess P1 in the presence of tris(2-carboxyethyl)phosphine. Unbound P1 is removed via dialysis. The DNA encoding the C7 linear protein block copolymer was cloned into the pET-15b vector (Novagen) and transformed into the BL21(DE3)pLysS Escherichia coli host strain (Life Technologies). The protein was expressed following isopropyl β-D-1-thiogalactopyranoside induction, purified by affinity chromatography via the specific binding of N-terminal polyhistidine tag to Ni-nitrilotriacetic acid resin (Qiagen), dialyzed against PBS, and concentrated by diafiltration across Amicon Ultracel filter units (Millipore). Each of the seven WW domains in C7 was treated as one C unit, and each pendant peptide group in PEG-P1 was treated as one P unit. SHIELD was formed by mixing C7 and PEG-P1 copolymer to achieve a C:P ratio of 1:1 and a final concentration of 10% w/v in PBS.