Polyethylene glycol diacrylate (PEGDA, 258 Da MW), phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide (Irgacure 819), 3-(trimethoxysilyl)propyl methacrylate, hydroxypropyl cellulose (HPC, 300 kDa), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), and dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich (Milwaukee, WI). 2-Nitrodiphenylsulfide (NPS) was from TCI America (Portland, OR). AlexaFluor 532 NHS ester (AF), acetone, and 2-propanol (IPA) were purchased from Fisher Scientific (Salt Lake City, UT). Glycine (G), ferritin (Fer), hydrochloric acid, sodium carbonate, and Amicon ultra 0.5 mL centrifuge filters were from Millipore Sigma (Billerica, MA). Sodium hydroxide was acquired from Mallinckrodt Specialty Chemicals (St. Louis, MO). Sodium bicarbonate monobasic was purchased from Merck (Burlington, MA). Toluene and glass microscope slides (3 × 1 in, 1 mm thick) were from Avantor (Center Valley, PA). Phenylalanine (F) was obtained from Spectrum Chemical (New Brunswick, NJ). PTB Peptide 1 (P1) and PTB Peptide 2 (P2) [39 (link)] were acquired from Biomatik (Wilmington, DE). Corticotropin releasing factor (CRF) was purchased from GeneScript (Piscataway, NJ). Lactoferrin (LF) was from Sigma (St. Louis, MO). Water purified to 18.3 MΩ·cm by a Barnstead EASYpure UV/UF system (Dubuque, IA) was used to prepare all solutions.