A dual-mode (colorimetric/fluorescence) nanoenzyme-linked immunosorbent assay (NLISA) was developed based on Au-Cu nanocubes generating Prussian blue nanoparticles (PBNPs). It is expected that this method can be used to detect the residues of sulfonamides in the field, and solve the problem of long analysis time and high cost of the traditional method. Sulfadimethoxine (SDM) was selected as the proof-of-concept target analyte. The Au-Cu nanocubes were linked to the aptamer by amide interaction, and the Au-Cu nanocubes, SDM and antibody were immobilized on a 96-well plate using the sandwich method. The assay generates PBNPs by oxidising the Cu shells on the Au-Cu nanocubes in the presence of hydrochloric acid, Fe³⁺ and K₃[Fe (CN)₆]. In this process, the copper shell undergoes oxidation to Cu²⁺ and subsequently Cu^2 +further quenches the fluorescence of the carbon point. PBNPs exhibit peroxidase-like activity, oxidising 3,3’,5,5’-tetramethylbenzidine (TMB) to OX-TMB in the presence of H₂O₂, which alters the colorimetric signal. The dual-mode signals are directly proportional to the sulfadimethoxine concentration within the range 10^− 3~10^− 7 mg/mL. The limit of detection (LOD) of the assay is 0.023 ng/mL and 0.071 ng/mL for the fluorescent signal and the colorimetric signal, respectively. Moreover, the assay was successfully applied to determine sulfadimethoxine in silver carp, shrimp, and lamb samples with satisfactory results.

基于产生普鲁士蓝纳米颗粒 (PBNP) 的金铜纳米立方体，开发了双模式（比色/荧光）纳米酶联免疫吸附测定 (NLISA)。预计该方法可用于磺胺类药物残留的现场检测，解决传统方法分析时间长、成本高等问题。选择磺胺二甲氧嘧啶 (SDM) 作为概念验证目标分析物。 Au-Cu纳米立方体通过酰胺相互作用与适体连接，并使用夹心法将Au-Cu纳米立方体、SDM和抗体固定在96孔板上。该测定通过在盐酸、Fe ³⁺和 K ₃ [Fe (CN) ₆ ]存在下氧化 Au-Cu 纳米立方体上的 Cu 壳来生成 PBNP 。在此过程中，铜壳被氧化成Cu ²⁺，随后Cu ²⁺进一步猝灭碳点的荧光。 PBNP 表现出类似过氧化物酶的活性，在 H ₂ O ₂存在的情况下将 3,3',5,5'-四甲基联苯胺 (TMB) 氧化为 OX-TMB ，从而改变比色信号。双模式信号与 10 ^{− 3} ~10 ^{− 7} mg/mL范围内的磺胺二甲氧嘧啶浓度成正比。该测定的荧光信号和比色信号的检测限 (LOD) 分别为 0.023 ng/mL 和 0.071 ng/mL。此外，该方法还成功应用于鲢鱼、虾、羊肉样品中磺胺二甲氧嘧啶的测定，结果令人满意。