The development of a method to produce diagnostic reagents using LaNiO3 nanospheres and their application in nanozyme-linked immunosorbent assay

Background: LaNiO3 perovskite nanoparticles, especially nanospheres (LNNS), show great promise in biomedical assays due to their peroxidase-like catalytic properties. Methods for synthesizing LaNiO3 nanoparticles of various shapes have been developed, with spherical and rod-shaped LaNiO3 showing better stability. However, LNNS-based diagnostic reagents have not been tested in nanozyme enzyme-linked immunosorbent assay (NLISA) or other enzyme-linked immunosorbent assays, and there is limited data on their synthesis. To fill this gap, it is necessary to develop a method for creating LNNS conjugates with monoclonal antibodies and to investigate the reproducibility, scalability, and applicability of these diagnostic reagents in NLISA. Results: We have successfully developed a method for producing novel diagnostic reagents utilizing LaNiO3 nanospheres. Our research demonstrates the application of these nanospheres in a NLISA specifically designed for the detection of C-reactive protein (CRP) in real serum samples. This method is both reproducible and scalable, allowing for the efficient production of nanospheres that are functionalized with monoclonal antibodies targeting CRP, with mean diameter of approximately 270 nm. Based on the promising results obtained from our experiments, we have developed and optimized a sandwich-format NLISA for CRP detection. This assay achieved lower limit of detection at 0.178 µg/L, with a dynamic range from 12.5 to 0.195 µg/L and a linear detection range extending from 0.195 to 6.25 µg/L, showcasing its potential for clinical applications. Significance and Novelty: The new NLISA method, utilizing LaNiO3 nanospheres in a sandwich format for the detection of CRP, significantly enhances sensitivity compared to similar use horseradish peroxidase-based -ELISA. In this study for the first time first the functionalization of lanthanum nickelate nanospheres with recognition elements have demonstrated. This advancement also sheds light on the technological challenges involved in synthesizing diagnostic reagents, identifying areas that need further exploration.