Enzyme-nanoparticle conjugates at oil-water interface for amplification of electrochemical immunosensing

► A catalytic capsule was synthesized from horseradish peroxidase (HRP) and HRP labeled anti-AFP (HAFP) coconjugated at gold nanoparticles, then entrapped at the oil-water interface. ► An AFP detection strategy was proposed by sandwich immunosensing with the prepared capsule as labels. ► The enhanced sensitivity was demonstrated by the proposed immunoassay.