Abstract Gold nanoparticle (AuNP) bioconjugates are increasingly being utilised in biomedicine due to their low toxicity on biological tissues and unique electronic and chemical properties. They have been utilised in several biological applications namely manufacture of nanomaterials, biosensing, electron microscopy and drug delivery systems. Particularly, immuno-assays often employ gold nanoparticles (AuNPs) to enhance detection of a biological component. This paper presents a study on the bioconjugation of AuNPs with an antibody against an oncoprotein that is overexpressed in cervical carcinoma progression through physical adsorption. The study successfully developed a HPV 16 E6/18 E6-HRP (CP15)-AuNPs bioconjugate. The study also demonstrated that the antibody pI, gold colloidal solution pH and amount of antibody determine the generation of stable Antibody–AuNPs bioconjugates. These results further demonstrate that physical adsorption can be used to produce functional Antibody–AuNPs that could be employed in diagnostic immunoassays.