Engineering europium nanoparticle-HIV-1 p24 conjugates as a novel platform for rapid and sensitive antibody detection

• Europium nanoparticle-p24 conjugates detect antibodies with picogram-level sensitivity. • EDC-NHS conjugation ensures stable and durable EuNP-p24 bioconjugates. • EuNP-p24 detect anti-p24 antibodies without effect of interferences in under one hour. • They show >90% recovery rate in clinical plasma sample testing. The detection and quantification of immune markers in biological samples play a critical role in various fields, including diagnostics, biomedical research, and therapeutics. Western blotting or enzyme-linked immunosorbent assays (ELISAs), which are labour-intensive and call for complicated processes, are frequently used in traditional immunodetection techniques. However, fluorescent nanoparticle-antigen conjugates have become an innovative method for immunogenic detection thanks to the recent developments in nanotechnology. This study demonstrates the fabrication and working principle of conjugates of fluorescent nanoparticles and HIV-1 p24 in antibody detection. Europium nanoparticles are the fluorophore conjugated to the HIV-1 p24 antigen, a capsid protein. Computational studies were conducted to determine whether the bioconjugation would be feasible, and the findings showed high stability of the conjugates. After validation, the bioconjugation of HIV-1 p24 and the nanoparticle was carried out using the EDC-NHS approach. Studies employing anti-HIV-1 p24 antibodies demonstrated that Europium nanoparticle-p24 (EuNP-p24) conjugates could achieve a sub-picogram-level sensitivity of 0.4 pg/mL and a very high recovery rate of ≥92 %, indicating their potential for improving the sensitivity of the assay and its efficiency in clinical diagnostics. EuNP-p24 conjugates have been designed and synthesized and have been tested for detection of Anti-HIV-1 p24 antibodies.