Passivation of KMPR microfluidic channels with bovine serum albumin (BSA) for improved hemocompatibility characterized with metal-clad waveguides

KMPR is an epoxy-based photoresist, similar to SU-8, featuring shorter processing times and superior resistance to fissuring. As such, KMPR is a material well-suited to microfluidic device fabrication in miniaturized biomedical instrumentation. However, like SU-8, KMPR requires surface treatment for hemocompatibility. In this work, we demonstrate that KMPR can be efficiently passivated with bovine serum albumin (BSA), improving hemocompatibility of the material surfaces. Experimental validation was conducted using fibrinogen adsorption as a hemocompatibility model. Protein adsorption to KMPR surfaces was measured using metal-clad waveguides (MCWG) with a KMPR film acting as the waveguide core layer. Passivation efficiency was compared both on natively hydrophobic KMPR and on hydrophilic KMPR treated with HNO3 catalyzed with ceric ammonium nitrate (CAN). Results show that the surface treatment significantly increases hemocompatibility for both hydrophilic and hydrophobic surfaces, with slightly better results in the case of hydrophobic surfaces. Post-treatment ultrasound wash had no observable effect, demonstrating that BSA adsorption to KMPR is robust. MCWG-based protein adhesion measurements were compared to that from conventional surface plasmon resonance (SPR) and long-range surface plasmon resonance (LR-SPR), confirming the validity of the measurements.