Improvement of immunoassay detection sensitivity by using well-defined raspberry-like magnetic microbeads as carriers

Well-defined raspberry-like magnetic microbeads (RMMBs) as immunoassay solid carriers were prepared by chemical covalent binding between Fe₃O₄ magnetic microspheres and SiO₂ nanoparticles. These RMMBs were not as agglomerative as nano-sized magnetie particles (< 200 nm), which was an advangtage for high efficient magnetic separation. When compared to Fe₃O₄@SiO₂ core-shell magnetic microbeads (CMMBs) with smooth surface, RMMBs exhibited stronger capacity to bind biomolecules. Limit of blank (LoB) and limit of detection (LoD) of HBsAg detection using RMMBs as carriers via chemiluminiscence immunoassay (CLIA) were 0.472 and 1.022 μg/L, respectively, showing a notable improvement compared with CMMBs whose LoB and LoD were 1.017 and 1.988 μg/L, respectively. All these indicated a great potential of RMMBs in immunoassay application.