To improve the detection sensitivity of neomycin (NEO) in milk, we produced a sensitive monoclonal antibody (mAb) against NEO and developed a lateral flow immunoassay based on amorphous carbon nanoparticles (ACNPs-LFA). First, we conjugated NEO to carrier protein to prepare mAbs. We obtained six mAbs: mAb 1C6, mAb 1D3, mAb 2D3, mAb 4D5, mAb 5D1, and mAb 5H1. We characterised the mAbs by indirect competitive enzyme-linked immunosorbent assay and selected the most sensitive mAb based on the half-maximal inhibitory concentration (IC₅₀). We selected mAb 4D5 (IC₅₀ = 0.15 ng/mL) for the development of LFA. MAb 4D5 was labelled with ACNPs (ACNPs-mAb 4D5) by electrostatic absorption. Under optimised conditions, 5.4 μg mAb 4D5 coupling with 1 mL ACNPs, NEO-OVA at concentration of 80 μg/mL, 3 μL ACNPs-mAb 4D5 were used to develop LFA. The cut-off value was 8 ng/mL. Therefore, our developed ACNPs-LFA is suitable for on-site detection of NEO residues.

Walnut male flowers (WMFs) are important by-products of walnut production. Studies on the nutritional quality of WMFs have predominantly focused on a single variety or region, and scientific information on different varieties is limited. In this study, ten walnut male flower (WMF) samples were evaluated and compared to assess their nutritional composition, bioactive contents, and antioxidant capacity. All WMF varieties were rich in protein, minerals, and amino acids, with leucine being the most abundant amino acid. All varieties exhibited low fat content and a favorable Na/K ratio. Additionally, they contained high levels of polyphenols and flavonoids, which were associated with strong antioxidant capacity. The variety seemed to exert a greater influence than the region on the nutritional composition and bioactive contents of WMFs. Moreover, polysaccharide, starch, soluble sugar, polyphenol, and fat might serve as potential markers for distinguishing different WMF varieties. This study provides a reference for the development and utilization of WMFs.