Four arm peg acrylate

Four-arm PEG–acrylate (10 kDa; 4-arm PEG–Ac) and PEG–dithiol (3.4 kDa; PEG–diSH) were obtained from Laysan Bio (Arab, AL, USA). PEG-diester-dithiol-1 (3.4 kDa; PEGDD-1) was synthesized in-house as described by us previously [26 (link)]. Fluoro-max red microspheres (2.0 µm in diameter, ex./em. 542 nm/612 nm) and human lys-plasmin native protein were obtained from ThermoFisher (Waltham, MA, USA). FluoroSpheresTM carboxylate-modified, infrared, 0.1 µm in diameter (ex./em. 715 nm/755 nm) were obtained from Invitrogen (Carlsbad, CA, USA). Bovine serum albumin (BSA), lysozyme, 1X phosphate buffer solution (PBS), 1X Dulbecco’s phosphate buffer solution (DPBS), triethanolamine (TEA), Bradford Protein Dye Reagent, and Triton X-100 were obtained from Sigma Aldrich (St. Louis, MO, USA). Olive oil was obtained from Costco (Issaquah, WA, USA). A 60-mL syringe and needles were obtained from Becton Dickinson (Franklin Lakes, NJ, USA) and 100 µL gas-tight syringe was obtained from Hamilton Company (Reno, NV, USA). Tubing and T-junctions for the microfluidic setup were obtained from Valco Instruments (Houston, TX, USA).

Eight‐well ibidi glass coverslips were plasma treated for 1 min and incubated with 2% v/v 3‐(Trimethoxysilyl)propyl methacrylate (440159, MilliporeSigma) in ethanol for 15 min, washed three times with ethanol and pressure air‐dried. 2 µL of 10% w/v four‐arm PEG acrylate (10 kDa, 4arm‐PEG‐ACRL‐10k, Laysan Bio) in 0.1% LAP in PS‐PBS were dropped in each well and sandwiched with an 8 mm coverslip and irradiated with 67.62 mW cm⁻² UV light for 30 s. 8 mm coverslips were removed and 80 µL of PEG acrylate solution were added on top of the PEG puck and flattened with a PDMS mold with a 7 × 7 pillar array of 500 µm diameter and 200 µm pillars. The platform was irradiated with 67.62 mW cm⁻² UV light for 30 s and the mold was removed to create a 7 × 7 array of 500 µm diameter and 200 µm wells.