Effect of horseradish peroxidase for the control of hydrogen peroxide mediated signal generation through the growth of gold nanoparticles

In classical colorimetric immunoassays the signal for detection is generated by a bio-catalytic conversion of a molecule (antigen or antibody) by an enzyme which acts as an amplifier. However, a sensitive and reliable immunoassay requires high selectivity and affinity of antibodies to their corresponding antigens that forms the principle of bio-recognition. If the presence of analyte is at very low levels, immunoassay is unable to detect them and as such necessitates the use of more sensitive methods. Nanoparticles (e.g. gold or silver colloids) represent a new signal generation mechanism for bio-sensing giving the required improvements in signal production. A catalytic approach involving hydrogen peroxide and gold nanoparticles has recently been demonstrated and has the potential to be applied to a wide variety of food safety targets such as chemical and microbiological contaminants, veterinary drug residues, and protein biomarkers.