Fast immunofluorescence lateral flow test strip approach for detection of homocysteine

• Published in: Micro & nano letters 2018-12, Vol.13 (12), p.1719-1723
• Main Authors: Chen, Wei, Ang, Chaoman, Lou, Doudou, Ji, Yongxin, Huang, Ling, Zhu, Yefei, Guo, Zhirui, Gu, Ning, Zhang, Yu
• Format: Article
• Language: English
• Subjects: biosensors; Biotin; biotin‐antibody; bio‐optics; cardiovascular disease; cardiovascular system; Catalysis; Chemical compounds; conjugate pad; Conjugates; diseases; enzymes; fast immunofluorescence lateral flow test strip; Fluorescence; fluorescence intensity; fluorescent nanospheres; fluorophores; Hcy S‐methyltransferase catalysis; Homocysteine; homocysteine detection; Immunofluorescence; independent risk factor; Methionine; molecular biophysics; nanofabrication; nanomedicine; Nanospheres; poly(styrene‐acrylate) copolymer nanospheres; polymer blends; Polystyrene resins; Reproducibility; Risk analysis; SAH‐bovine serum albumin; sample diluents; Serum albumin; signal amplification; signal amplification label; streptavidin; Strip; Substrates; S‐adenosyl Hcy; S‐adenosyl methionine
• ISSN: 1750-0443; 1750-0443
• DOI: 10.1049/mnl.2018.5040

The study developed a novel quantitative detection method of homocysteine (Hcy), an independent risk factor for cardiovascular disease, based on an immunofluorescent test strip. The fluorescent nanospheres (F-NSs) were prepared by embedding fluorophores (Cy5) into poly(styrene-acrylate) copolymer nanospheres, then conjugated with streptavidin (SA) to obtain SA/F-NSs as a signal amplification label stored in sample diluents. Biotin–antibody was fixed on the conjugate pad to specifically capture S-adenosyl Hcy (SAH) in the sample, where SAH was transformed from S-adenosyl methionine (SAM) by Hcy S-methyltransferase catalysis using Hcy as a substrate, the formed SAH could be trapped by SA/F-NSs and biotin–antibody conjugates in a competitive way with SAH–bovine serum albumin fixed on the test line, a detection limit of 0.27 μM Hcy was achieved. The fluorescence intensity of F-NSs remained stable during 273 days of storage, the bioactivity of the test strip was stable during 12 months of storage, and the strip possessed good reproducibility (intra-assay variability of 5.8%). Furthermore, other structural analogues SAM and cysteine showed negative results, validating the excellent specificity of the strips.