Characterisation and determination of stability and functionality of biofunctionalised colloidal gold nanoparticles

Colloidal gold nanoparticles were conjugated with oligonucleotides to create biorecognition nanomodules. The efficiency of conjugation was determined by fluorescence using a FITC-labelled thiolated model probe and by enzyme-linked nanoparticle assay (ELINA) using a digoxigenin-labelled thiolated model probe. The thermal stability of the conjugation was determined by displacement and fluorescence measurement of the FITC probe. Functionality for hybridisation was determined by enzyme-linked oligonucleotide assay (ELONA). It was found that the equilibrium oligonucleotide surface coverage reached 37% of the total nanoparticle area. These results could be verified by ELINA. Under hybridisation conditions that allowed the detection of 4-point mutations on a target 19-mer sequence (1 h at 65 °C), it was found that the biofunctionalised nanomodules lost between 10 and 30% of the conjugated biorecognition molecules.