phosphate monobasic monohydrate, sodium
phosphate dibasic anhydrous, and sodium periodate (NaIO4) were purchased from Acros Organics (Fair Lawn, New Jersey). Phosphate
buffer saline (PBS, 1×) was from Fisher Scientific Co. (Pittsburgh,
Pennsylvania). Fresh bovine pericardium was purchased from Sierra
for Medical Science (Whittier, California). Pericardium tissues were
cut into the desired dimension (2.5 cm × 2.5 cm), incubated in
buffer solution of a desired pH (10 mM sodium phosphate buffer adjusted
to a pH of 5.7, 6.7, 7.4, or 8.0) for 2 days and kept frozen until
testing.21 (link) pH treatment had no impact on
the tensile modulus of the tissue substrate (
S1
using 4-armed 10k Da N-hydroxysuccinimide ester activated
poly(ethylene glycol) purchased from JenKem USA, Inc. (Allen, Texas).