Natural enzyme-free colorimetric immunoassay for human chorionic gonadotropin detection based on the Ag+-triggered catalytic activity of cetyltrimethylammonium bromide-coated gold nanoparticles

• Published in: Sensors and actuators. B, Chemical Vol. 305; p. 127439
• Main Authors: Guo, Yuqian, Zhou, Yaofeng, Xiong, Sicheng, Zeng, Lifeng, Huang, Xiaolin, Leng, Yuankui, Xiong, Yonghua
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.02.2020; Elsevier Science Ltd
• Subjects: Ag+-triggered catalytic activity of AuNPs@CTAB; Catalytic activity; Cetyltrimethylammonium bromide; Colorimetric immunoassay; Colorimetry; Gold; Human chorionic gonadotropin detection; Hydrogen peroxide; Immunoassay; Morphology; Nanoparticles; Nanorods; Nanospheres; Natural enzyme-free; Peroxidase; Robustness; Sensitivity enhancement; Silver; Ag+-triggered catalytic activity of AuNPs@CTAB; Natural enzyme-free; Human chorionic gonadotropin detection; Colorimetric immunoassay
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2019.127439

•A natural enzyme-free colorimetric immunoassay was developed for human chorionic gonadotropin detection.•AuNP@CTAB was first designed as a signal transducer to overcome the bottleneck of nanozyme activity loss.•The morphology-dependent catalytic properties of the three shaped AuNPs@CTAB were investigated.•Compared with traditional ELISA, the proposed method demonstrated similar detection sensitivities but was highly robust. The usage of nanozyme as label to establish immunoassays offers merits of low cost and high robustness. However, the catalytic activity of nanozyme is usually passivized by the modified layer of bio-recognition molecules. The peroxidase-mimicking activity of cetyltrimethylammonium bromide (CTAB)-coated gold nanoparticles (AuNPs@CTAB) is recovered by Ag+ ions. Herein, AuNPs@CTAB with Ag+-triggered catalytic activity was first designed as signal transducer to construct colorimetric immunoassay for human chorionic gonadotropin (HCG) detection. Silver nanoparticles were used as labels which can release numerous Ag+ ions by hydrogen peroxide corrosion and thus enhance the catalytic activity of AuNPs@CTAB. To achieve the highest detection sensitivity, we synthesized three kinds of AuNPs@CTAB with similar size but different shapes including nanospheres (AuNSs@CTAB), nanorods (AuNRs@CTAB), and nanocubes (AuNCs@CTAB). The morphology-dependent catalytic properties of AuNPs@CTAB were evaluated. Under optimum conditions, the proposed method using AuNSs@CTAB, AuNRs@CTAB and AuNCs@CTAB using AuNSs@CTAB, AuNRs@CTAB and AuNCs@CTAB gave LOD of 7.8, 15.6 and 31.2 mIU/mL, respectively. The developed immunoassays also showed good accuracy, high reproducibility and high robustness for detecting HCG in serum samples. In summary, the developed immunoassay is a promising bioanalysis platform which can provide similar sensitivity and enhanced robustness compared with traditional horse radish peroxidase-based immunoassays.