Determination of collagen type IV by Surface Plasmon Resonance Imaging using a specific biosensor

Serum collagen type IV (COLIV) is a promising tumor marker. High COLIV concentrations have been found in the serum of patients with colorectal, gastric, lung, liver and breast cancers. The aim of this work was to develop a biosensor for use with the Surface Plasmon Resonance Imaging (SPRI) technique for COLIV determination. The biosensor consists of glass covered with gold and immobilized monoclonal mouse anti-human collagen type IV antibody via cysteamine linker. The biosensor works selectively within a dynamic response range between 10 and 300 ng mL^-1, with LOD 2.4 ng mL^-1 and LOQ 8 ng mL^-1. The precision of determination is 4.7% at a 150 ng mL^-1 COLIV spike and 8.0% at a 20 ng mL^-1 spike, with recoveries of 101% and 106% respectively. A 100-fold excess of collagen I, albumin, laminin and fibronectin is tolerated. The average COLIV blood plasma concentration of healthy donors determined by the developed method was 69 ± 10 ng mL^-1, while the median of six results available in the literature was approximately 80 ng mL^-1. The average COLIV blood plasma concentration of breast cancer patients was 360 ± 68 ng mL^-1, showing the high potential of COLIV as a marker of this type of cancer.