To an aqueous solution of fluorescein-tagged Pertuzumab conjugates (FluoroPer), borate buffer and AuNP solution (NanoComposix) were added sequentially prior to incubation under agitation. Following this, the physisorption mixture was blocked with blocking buffer and further incubated under agitation. Blocked mixtures were then centrifuged, forming a free-flowing pellet of colloid from which supernatant was extracted. The colloidal pellet was then washed by re-suspension in blocking buffer and then centrifuged prior to supernatant extraction. This washing procedure was repeated twice more prior to the characterisation of FluoroPerAuNPs.