Collagen 1 bovine protein solution

Unless otherwise noted, all chemicals and solvents were of analytical grade and used as advised by the manufacturer. 4 and 8-arm PEG succinimidyl glutarate (PEG) was purchased from JenKem Technology (Texas, USA). Collagenase, dimethyl sulfoxide (DMSO), fluorescamine, sodium hydroxide solution (1.0 N), bovine serum albumin (BSA), fibronectin, cholera subunit A, insulin, Triton-X, and Cell Counting kit-8 were purchased from Sigma-Aldrich (St. Louis, MO, USA). Phosphate-buffered saline (PBS) pH 7.4, 10X PBS, Slide-A-Lyzer dialysis kit (3.5 kDa MWCO), collagen I bovine protein solution (5 mg/mL), Collagenase, Dulbecco’s modified eagle medium nutrient mixture F-12 (DMEM/F-12) with 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), insulin-transferrinselenium (ITS), Dulbecco’s phosphate-buffered saline (DPBS), antibiotic-antimycotic, Live/Dead viability/cytotoxicity staining kit, and paraformaldehyde (PFA) were purchased from Thermo Fisher Scientific (Massachusetts, USA).

Dibenzocyclooctyne-sulfo-N-hydroxysuccinimidyl ester (DBCO-sulfo-NHS), dimethyl sulfoxide (DMSO), sodium hydroxide solution (1.0 N), agar, insulin, Triton-X, trypan blue solution, hyaluronidase type VI-S, collagenase type I, and resazurin based in vitro toxicology assay kit were purchased from Sigma-Aldrich (St. Louis, MO, USA). Phosphate-buffered saline (PBS) pH 7.4, 10× PBS, Slide-A-Lyzer dialysis kit (3.5k MWCO), collagen I bovine protein solution (5 mg mL⁻¹), epidermal growth factor (EGF) recombinant human protein, fetal bovine serum (FBS), keratinocyte-serum free media (KSFM), bovine pyruvate extract (BPE), ITS Premix Universal Culture Supplement, trypsin, live/dead viability/cytotoxicity staining kit, paraformaldehyde (PFA), 5% normal goat serum, Alexa Fluor Phalloidin 488, Alexa Fluor 647-N-hydroxysuccinimidyl ester, and Alexa Fluor 546 secondary antibody were purchased from Thermo Fisher Scientific (Waltham, MA, USA). Azido-poly(ethylene glycol)₅-N-hydroxysuccinimidyl ester (azido-PEG5-NHS) was purchased from BroadPharm (San Diego, CA, USA). Hyaluronate amine (40–50% degree of substitute) was purchased from Creative PEGWorks (Durham, NC, USA).