Gold nanostructures in mediating high-performance medical diagnosis of human blood disease biomarkers

The current research was carried out using three (3) different human blood disease biomarkers which were C-reactive protein (CRP), blood clotting factor IX (FIX) and squamous cell carcinoma antigen (SCC antigen). Two different types of dual probing system electrode were utilized in this research. A nano gapped electrode with the gap of ~100 nm was designed and modified to capture the target, CRP. Meanwhile, factor IX and SCC antigens were diagnosed by using an interdigitated electrode (IDE), which had finger like structure with the zinc oxide surface. In order to increase the amount of antigen to be captured a gold nanorod (GNR) of a 119 nm in length and 25 nm in width was integrated in CRP detection system. In addition, gold nano-urchins (GNUs) with 60 nm in diameter was integrated into a streptavidin-biotinylated aptamer strategy in Factor IX diagnosis technique. Whereby, dispersed and agglomerated state of gold nanoparticles with 30 nm was used in SCC antigen detection scheme. The physical characterization for the sensing surface and gold nanostructures was properly carried out atomic force microscopy, scanning electron microscopy, 3D nano-profilometry, high-power microscopy and UV–Vis spectroscopy. A comparative analysis in the existence and non-existence of gold nanostructures utilization was performed using electrical characterization. The amperometric measurement by a linear sweep voltage of 0 to 2 V at 0.01 V step voltage was implemented to study the sensitivity and specificity of the blood biomarker interaction. Current research using three different biomarkers which responsible for three different blood disease reveals a lower limit of detection as compared to real concentration of specific biomarkers in human serum. The obtained detection limit as low as pico- to femtomolar range was due to the conjugation of gold nanostructures with antibody (Probe) and the strategy used like streptavidin-biotinylated aptamer for Factor IX detection. Hence, the highlighted novelty of the research is the utilization of different gold nanostructures and also the strategy applied to enhance the detection system. Hence, gold mediated high-performance sensing able to lower the limit of detection down to pico- to femto-molar ranges and hold an outstanding performance in biosensing application.