Antibody fragment immobilization on planar gold and gold nanoparticle modified quartz crystal microbalance with dissipation sensor surfaces for immunosensor applications

Abstract

Immunosensors are bioaffinity sensors incorporating immune system molecules that are utilized for analyte recognition and signal transduction yielding a measurable signal upon analyte detection. A lot of effort has been made to optimize the immobilization matrix on the sensor surface since the outcome of the ligand immobilization procedure determines sensitivity, specificity and longevity of the developed immunosensor. In this work, antibodies against bovine leukemia virus antigen gp51 were chemically reduced to “half” antibody fragments that were later employed as recognition ligands. Antibody fragments at different concentrations were immobilized via thiolate bonds on planar gold and gold nanoparticle modified surfaces of a quartz crystal microbalance with dissipation sensor. Antibody fragment immobilization and interaction with antigen were investigated. Antibody fragment surface mass densities after the immobilization on planar gold and gold nanoparticle modified sensor surfaces were directly dependent on the initial antibody concentration. The highest analytical response was exhibited by antibody fragments immobilized at the smallest surface mass density on planar gold and gold nanoparticle modified surfaces. Bovine leukemia virus antigen gp51 interaction with antibody fragments was compared with non-specific gp51 interaction with bovine serum albumin on planar gold and gold nanoparticle modified surfaces by employing ΔD/Δf plots.