Colloidal gold nanoparticles are investigated as a potential scaffold for the assisted immobilisation of probe oligonucleotides on silicon surfaces. A preliminary study is devoted to the examination of the immobilisation of DNA-modified gold nanoparticles as a function of time, concentration, salt and pH. The DNA-modified nanoparticles self-assembled onto solid surfaces in a three-dimensional self-assembled architecture. The functionalised surfaces are evaluated in diagnostic assays, where their potential to improve the efficiency of the hybridisation reaction is tested. The system utilising DNA-modified nanoparticles produced an enhancement in the hybridisation efficiency and the sensitivity limit by a factor 10 to 100 as compared to a conventional DNA immobilisation system on a planar surface.