Real-time binding curves and Langmuir one-to-two fittings of anti-biotin reactions with surface (A) 40× biotin-bovine serum albumin, (B) 20× biotin-bovine serum albumin, (C) 10× biotin-bovine serum albumin, (D) 5× biotin-bovine serum albumin, (E) 4% biotin-polyvinyl alcohol, and (F) 2% biotin-polyvinyl alcohol. Different colors represent different probe concentrations (black: 27 nM; red: 80 nM; blue: 240 nM; green: 480 nM), and dotted lines indicate fittings. All fitting parameters are listed in Table 4.