Immunofluorescence and two-dimensional visual analysis of HIV-1 p24 antigen in clinical samples enhanced by poly-T templated copper nanoparticles and QDs

In this study, we reported a dual-mode fluorescence and two-dimensional color and distance visual reading technique for HIV-1 p24 antigen immunoassay using polyT-templated Cu NPs as the bridge and signal. Mode 1 combined the phenomenon of Cu2+ and Cu NPs being distinguished by CdTe QDs using the ink jet printing technology, which was introduced to make test strips. In mode 2, a highly sensitive p24 antigen analysis method was developed by combining the characteristics of terminal deoxyribonucleotidyl transferase (TdT) catalyzed primer and dTTP substrate extension to generate polyT, and using polyT-templated Cu NPs as signal reporters. Mode 1 with QDs as signal reporters achieved color and distance visual reading analysis of p24 antigen at pg/mL level, whereas mode 2 with Cu NPs as signal reporters achieved fg/mL level analysis sensitivity. This method was used to quantify p24 antigen in the serum of 20 patients with acute HIV infection. The results were highly consistent with those of laboratory electrochemiluminescence immunoassay (ECLIA), quantitative viral RNA results from by polymerase chain reaction (PCR), and clinical diagnosis. The serum of 10 normal people and 16 patients suffering from other diseases had no discernible effect on the p24 antigen analysis method. Therefore, this work provides solutions for early diagnosis of HIV infection in the future, as well as for point-of-care testing (POCT) in remote areas.