Qualitative and quantitative thrombin analysis in serum using aptamers and gold nanoparticles through progressive dilution

It has been a long-standing challenge in bioassay using aptamers and gold nanoparticles to detect disease-related proteins and other substance directly in complex biological samples such as serum. Here we propose a progressive dilution (PD) method to achieve simultaneous qualitative and quantitative analysis of proteins in blood serum without pretreatment of the sample. Above the detection limit, PD has unlimited dynamic range. We demonstrate the PD strategy through the detection of thrombin in fetal bovine serum using the quenching of fluorescence by gold nanoparticles.