This BSA detection model was adopted from the references
[6,10]. The protein assay is based on the nonspecific binding of BPB
to proteins. BPB binds to proteins through a combination of electrostatic
and hydrophobic interactions. Under acidic conditions, BPB
can interact with BSA to form a stable blue complex. We immobilized
samples on the paper strip instead of dipping paper into the
sample solution, which could largely reduce the volume of samples
needed.