Figure 4.

Effect of sample matrix. Thrombin was prepared at different concentrations (1, 13.50 nM; 2, 2.70 nM; 3, 1.35 nM; 4, 0.27 nM; 5, 0 nM) in a variety of matrices ((A) PBS, (B) 1% milk, (C) BHI broth, and (D) beef bouillon) and then spotted on polyester cloth strips with (a) and without (b) immobilized Apt 4, followed by immunoenzymatic assay of bound thrombin as described in Methods. These experiments were repeated in a separate trial with identical results (not shown).