<p>In the present study, one-step sandwich immunoradiometric assay (IRMA) for human Luteinizing hormone (LH) using monoclonal, anti-LH antibody bioconjugated to magnetizable cellulose particles containing manganese ferrite (Mn_0.1Fe_0.9Fe₂O₄) core is described. Anti-LH antibodies directed against two different epitopes of LH were used. LH antibody functionalized magnetizable cellulose containing manganese ferrite core using optimized bioconjugation strategy was used as a solid phase capture antibody, whereas, ¹²⁵I-labelled anti-LH antibody was used as a detector antibody. The developed IRMA demonstrated low nonspecific binding (NSB) and wide working range with excellent precision. This approach demonstrates the potential of antibody bioconjugated to magnetizable cellulose containing manganese ferrite core as a platform for developing high-performance immunoassays for clinical diagnostics.</p>