Optimization of diamond sensor for trace detection of SARS-CoV-2 N-protein using Au nanoparticles

In this study, Au nanoparticles were introduced to functionalize hydrogen-terminated diamond (H-diamond) to optimize surface modification and improve the performance of diamond sensor for trace detection of SARS-CoV-2 N-protein. The Au nanoparticles were obtained by an electron beam evaporation system and annealing. Atom force microscope and scanning electron microscope were utilized to characterize the structure, morphology, and distribution of fabricated Au nanoparticles. The concentration of SARS-CoV-2 N-protein was determined by the investigation of transfer characteristics of a diamond solution gate field effect transistor. Sensitivity of this sensor was obtained as 27.43 mV/lg (N-protein concentration), which was higher than a regular H-diamond sensor. In addition, it had a wider linear detection range of 10⁻¹⁵-10⁻⁵ mg/ml and a lower limit of detection of 10⁻¹⁵ mg/ml. Accordingly, the detection performance of diamond sensor has been greatly improved due to the functionalization of Au nanoparticles.