Optical waveguide lightmode spectroscopy immunosensor for detection of carp vitellogenin

Label-free, optical waveguide lightmode spectroscopy (OWLS) based immunosensors were developed for vitellogenin (Vtg) determination in carp (Cyprinus carpio). Purified polyclonal serum raised in rabbits against lipovitellin (Lpv) purified from carp ovary and shown to fully cross-react with Vtg was applied both in direct and indirect measurement formats, and analytical features (limit of detection, specificity, matrix effects) were investigated. The direct OWLS immunosensor and the sandwich ELISA assay developed showed linear measuring range in 600–12,000 ng mL−1 and 200–3000 ng mL−1 Lpv concentrations in standard solutions, respectively. The competitive immunosensor allowed a sensitive detection range for Lpv between 3 and 100 ng mL−1. Vtg content in blood and liver samples from male and female carp were determined by indirect OWLS. To reduce the matrix effect, calibration curves were obtained using Vtg-free blood and liver samples from male carp spiked with Lpv. Vtg levels in the liver of female carp was lower than determined in the blood samples, therefore, blood occurs to be a more proper tissue to monitor elevated Vtg in male carp due to possible exposure to water-contaminating endocrine disrupting chemicals.