Chujun Zheng,Qixia Jiang,Kan Wang,Tangan Li,Wei Zheng,Yuemeng Cheng,Qihong Ning,Daxiang Cui
In this study, we developed a novel magnetic lateral flow assay based on iron oxide decorated with platinum probes (Fe3O4@Pt) for dual-mode detection of gastrin-17 (G-17), which is one of the main biomarkers for early gastric cancer diagnosis. The probe material exhibits both magnetic properties and peroxidase activity. The peroxidase activity enhances the intensity of the brownish coloring of the Fe3O4@Pt probes on the test strip, with a limit of detection of 10 pg mL−1 using the naked eye, which is remarkable for colorimetric lateral flow assays. The magnetic property allows the simple separation and enrichment of the sample, and the signal can be read using a magnetic assay reader for quantitative detection. The linear range for G-17 using the magnetic signal was determined as 10 pg mL−1 to 2200 pg mL−1, and the calculated limit of detection was as low as 3.365 pg mL−1, thereby covering the reference range for G-17. Serum samples were used to validate the test strip, which exhibited high sensitivity, high specificity, and consistency with the results obtained by the enzyme-linked immunosorbent assay method. The entire inspection process using this method can produce results within 35 min and it is simple to operate without requiring strict experimental conditions. This dual-mode lateral flow test strip provides a simple, rapid, and quantitative strategy for detecting G-17, and it may also be valuable in other portable diagnostic applications.
Xintong Li,Jiale Cui,Jin Li,Yulian Wang,Guoqing Shi
Gastrin 17 (G-17) is a major biomarker for the diagnosis of gastric cancer. As the serum concentrations of gastrin are low, highly sensitive detection methods are needed. Previous studies have shown that oriented immobilization of detection antibodies can improve the sensitivity of lateral flow immunoassay (LFIA) methods. Herein, the antibody binding capacity of four Fc-specific peptides reported in different studies was evaluated, and two peptides with better binding potency were further modified with cysteine or the peptide GAC at their C-terminus. The peptide FYWHCLDEGAC exhibited the highest antibody binding capacity and was applied to directly immobilize the anti-G-17 antibody on microspheres with carboxyl-functionalized surfaces and europium-based time-resolved fluorescence. An LFIA method was developed to detect G-17 in human serum, and the limit of detection (LOD) of this method for G-17 was 0.08 pmol L -1 , which was 10 times less than that of the nonoriented immobilization method. The working range of this method is 0.27 ∼ 600 pmol L -1 , with a recovery rate of 85.2 % −106.7 % and a CV value less than 12.4 %. This method is easy to use, and the total detection process takes less than 20 min. The test results for the actual serum samples were consistent with the commercial kit results (R 2 > 0.95), demonstrating that the method can be utilized for point-of-care testing of G-17. This approach to orientedly immobilize antibodies on nanomaterials can be used to develop sensitive LFIA methods for various molecules.
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