This BSA detection model was adopted from the references
[6,10]. The protein assay is based on the nonspecific binding of BPB
to proteins
The BPB dotted on the paper runs altogether with water and reacts with BSA,
leaving a blue dot where the BSA was immobilized. Color disparities of
the blue dots indicate different concentrations of BSA. The remnant of
BPB was washed to the end of paper strip by water, rather than
staying with the blue dot and thus affecting the analysis of colors.