Gold nanoparticles/horseradish peroxidase encapsulated polyelectrolyte nanocapsule for signal amplification in Listeria monocytogenes detection

Bioconjugate nanocapsules were fabricated by using polystyrene sulfonate (PSS) to encapsulate gold nanoparticles (AuNPs) bearing adsorbed horseradish peroxidase (HRP). The average size of nanocapsule was in a range 150–400 nm. The efficiency of the capsules to enhance signals in an immunoassay was demonstrated by using an enzyme linked immunosorbent assay (ELISA) to detect the food-borne pathogen – Listeria monocytogenes. The antibody adsorbed onto the PSS shell of the nanocapsules provided the recognition molecule. For a given quantity of antibody, the bioconjugate nanocapsules showed 30 times greater sensitivity and a shorter assay time (5 min) when compared to conventional ELISA using an HRP labelled antibody. This proof-of-concept encapsulation of HRP through PSS nanocapsules may pave the way for alternative signal enhancement strategies where sensitivity is a priority.

► We develop a simpler method of nanocapsule formation by using polystyrene sulfonate (PSS) to encapsulate gold nanoparticles (AuNPs) bearing adsorbed horseradish peroxidase (HRP).
► We demonstrate the efficiency of the nanocapsule to enhance signals in an enzyme linked immunosorbent assay (ELISA) to detect the food-borne pathogen – Listeria monocytogene.
► This bioconjugate nanocapsules shows 30 times greater sensitivity and shorter assay time (5 min) when compared to a conventional ELISA using an HRP labeled antibody.