{
    "protocol": "Preparation of PVA-WI coating: PVA with the mass of 3.6 g was dissolved in 15 ml water and stirred for 2 h at 95°C. After defoaming, the resultant solution was spread on the glass slides to produce a uniform liquid layer with different thickness (25, 100, 200 µm) using a wet film coater. To obtain dry PVA-WI coated substrates, the samples were dried at 25°C for 24 h. Preparation of PVA-SI coating: Oxygen plasma-treated glass slides were immersed in a mixture of 90 ml ethanol, 10 ml water, 5 ml 3-glycidoxypropyltrimethoxysilane, and 100 µl acetic acid at room temperature for 12 h. After cleaning, the epoxy-functionalized glass slides were prepared. PVA with the mass of 3.6 g was dissolved in 15 ml water (pH=2) and stirred for 2 h at 95°C. After defoaming, the resultant solution was spread on the epoxy-functionalized glass slides to produce a uniform liquid layer with different thickness (25, 100, 200 µm) using a wet film coater. The samples were placed in a 60°C oven for 12 hours to complete chemical grafting of PVA. To obtain dry PVA-SI coated substrates, the samples were dried at 25°C for 24 h."
}