Fig. 3: Surface modification and detection performance of the PIDS for SARS-CoV-2 spike proteins, pseudo virus and live virus.

a, b Reaction principle of the SARS-CoV-2 with antibodies modified on graphene surface in PBS solution. c Elemental analysis of the graphene before and after PBASE modification using X-ray photoelectron spectroscopy. d C1 peaks of PBASE activated graphene from 282 eV to 292 eV, including C=C, C=N, C-N, C-OH, C-C=O/C=O and π-π bonding. e Dose-dependent current curve of PIDS to SARS-CoV-2 spike proteins. Graphene was modified with antibody 1 (spike S1 antibody, Cat: 40150-R007) that was reactive with wide type (WT), Alpha, Delta and Omicron. The antigen protein was spike S1 His Recombinant Protein (Cat: 40591-V08H). f Specific detection of PIDS to SARS-CoV-2. The used antigen proteins involved BSA, MERS-CoV, SARS-CoV and SARS-CoV-2. g, h Selective identification of Delta and Omicron by modifying antibody 2 (Cat:40592-MM57) and antibody 3 (Cat:40591-MM48) on graphene, respectively. i–l Detection ability of PIDS modified with antibody 1 to pseudo viruses including WT, Alpha, Delta and Omicron. The box ends represent the standard deviation (SD). The horizontal line in each box represents the mean value. The upper and lower whiskers refer to the range of non-outlier data values. Outliers were plotted as individual points. m–p Detection ability of PIDS modified with antibody 1 to the live viruses including WT, Alpha, Delta, and Omicron. The experiment was conducted in physical containment level 3 laboratory. The concentration range was from 500 fg ml⁻¹ to 500 pg ml⁻¹. The error bars in e–h and m–p correspond to the SD. The average current values and error bars were calculated using the recorded 1200 stable current values (n = 1200) of each test. Data are presented as mean values ± SD. Source data are provided as a Source Data file.