After a visual color change occurred from pale brown to dark bluish green color, 1 mL of CTAC solution was added to stabilize the particles. The solutions were transferred into 50 mL centrifuge tubes and left to spin for 30 minutes. After spinning, the nanoparticles were centrifuged at 4,000 g for 10 minutes. The supernatant was removed, and the pellet was redispersed in a mixture of 9 mL of Milli-Q water and 1 mL CTAC. After that, the mpGNS was magnetically purified to separate from gold nanostars impurity. After five minutes, the supernatant was removed, and the concentrated particles were combined into 1 mL of solution with Milli-Q water and mixed with mPEG-NHS-SH for further antibody functionalization. Antibody titers were determined using indirect ELISAs, where RVFV rNP (The Native Antigen Company, Kidlington, United Kingdom) was immobilized onto assay plates. Splenocytes were harvested from immunized mice, and hybridoma fusion was carried out following a standard protocol. Monoclonal antibodies were subsequently purified from hybridoma cell culture supernatants via protein A affinity chromatography.