We　have　improved　real-time　immuno-PCR　(IPCR)　with　nanoparticle　based　amplification.　Gold　magnetic　particles　were　functionalized　with　antibodies　against　the　HIV　capsid　protein　p24　and　gold　nanoparticles　were　functionalized　with　both　oligonucleotide　barcodes　and　antibodies　against　a　nonoverlapping　region　of　the　cognate　p24.　In　the　presence　of　p24,　the　gold　magnetic　particles　and　the　gold　nanoparticles　form　sandwiched　structures　that　are　magnetically　separated　from　mixture.　After　dehybridization　of　the　barcode　DNA　on　the　gold　nanoparticle,　the　released　barcodes　are　quickly　identified　by　realtime　PCR.　The　limit　of　detection　was　100　copies　of　p24　antigens.　Results　show　that　the　real-time　IPCR　through　nanoparticle　based　barcode　amplification　offers　an　disruptive　approach　to　p24　detection　and　quantification,　thus　may　potentially　shorten　the　window　of　HIV-I　diagnosis,　and　might　be　valuable　to　monitor　the　response　to　anti-retroviral　treatment　when　RNA　copy　number　is　very　below.　©　2007　Crown　Copyright.