Fast measurement of binding kinetics with dual slope SPR microchips

Abstract

We demonstrate a new dual slope SPR technique that is ten-fold faster than the conventional step-response method. The new scheme utilizes rapid slope-based measurements followed by rapid reset, and it separates association and dissociation half reaction measurements at two separate sites inside a dual-chamber PDMS microfluidic chip. For a model CAII-ABS test system, the association and dissociation slopes were measured in 30 seconds compared to 5 minutes for step-response. The values of k_a and k_d calculated from the slope method are 3.66 ± 0.19 × 10³ M⁻¹ s⁻¹ and 4.83 ± 0.17 × 10⁻² s⁻¹, respectively, matching well with step-response values while facilitating ∼10 to 15 fold faster detection and quantification.