{
    "protocol": "The synthesis of hydrophilic polymers with functional groups involves several steps: First, degrease the glass substrates by sonication in a 4% (v/v) solution of Micro-90 for 15 min, followed by two rinses in deionized water for 15 min, and then dry with compressed air. Treat the cleaned glass with oxygen plasma for 2 min at 150 mTorr. Build layer-by-layer (LbL) assemblies of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) using a spin dipper with 10 min dipping times in 1 mg/mL polymer solutions at pH 2.0, rinsing three times (2, 1, and 1 min). The PVA/PAA multilayer film is cross-linked thermally for 5 min at 140°C. For PEG functionalization, immerse the PVA/PAA multilayer in a 10 mg/mL PEG solution (pH 2.0) for 20 min, then soak in 0.13% (w/w) glutaraldehyde in phosphate buffer saline for 10 min, followed by rinsing with deionized water and drying. For PMMA coating, dissolve PMMA in Asahiklin at 10 mg/mL, dip-coat on the pretreated glass for 1 h, and heat at approximately 60°C for 1 h to evaporate the solvent."
}