Human serum albumin interference on plasmon-based immunokinetic assay for antibody screening in model blood sera

The effect of human serum albumin (HSA) on an immunokinetic assay for an antibody to bovine serum albumin has been determined in model serum solutions with HSA concentrations in the range 0 to 450 μM (0–30 mg ml−1). The assay is performed on two plasmon-based detection platforms: a continuous gold surface and a nanoparticle-based array reader. The assay has a minimum detection concentration of 760 ± 160 pM (120 ± 25 ng ml−1) in phosphate-buffered saline, falling to 2.5 ± 0.7 nM (380 ± 100 ng ml−1) in physiological HSA concentration. The concentration of HSA correlates with the refractive index of the solution, and this may be used to calibrate assay response. The addition of the charged chaotrope SCN− in 150 mM concentration improves the reproducibility and consistency of the assay, with a minimum detection concentration of 2.9 ± 0.5 nM (440 ± 80 ng ml−1). The effect of high concentrations of HSA on the immunokinetic assay can be corrected with a measurement of bulk refractive index in a reference channel.