Sensitive chemiluminescence immunoassay for staphylococcal enterotoxin C1 based on the use of dye-encapsulated mesoporous silica nanoparticles
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A chemiluminescent immunoassay for the staphylococcal enterotoxin C1 (SEC1) based on the use of dye-encapsulated mesoporous silica nanoparticles (m-SiNPs) as a label is described. The dyes are retained in the m-SiNPs via strong hydrophobic interactions. The assay comprises the following steps: (a) Microplates coated with antibody against SEC1 are filled with sample upon which the SEC antigen will be bound to the surface; (b) following a washing step, secondary antibody linked to m-SiNPs (that were covalently labeled with rhodamine 6G and fluorescein) were added to form the sandwich complex; (c) after another washing step, bis(2,4,6-trichlorophenyl) oxalate, H2O2 and imidazole are added to generate chemiluminescence whose intensity is proportional to the number of m-SiNPs and thus to the number of antigen (SEC) molecules. It is found that the use of functionalized m-SiNPs strongly amplifies the signal. Enterotoxin SEC1 can be detected by this method in the 0.025 to 2 ng⋅mL‾1 concentration range, the detection limit is 19 pg⋅mL‾1 (at 3σ), and the relative standard deviation (for 11 parallel measurements at a 1 ng⋅mL‾1 level) is 4.6 %. The use of an automated chemiluminescence analyzer further improves detection.
KeywordsNanomaterial Sandwich immunoassay Bis(trichlorophenyloxalate) Microplate assay Bioassay Rhodamine 6G Fluorescein Staphylococcus aureus SEC1 Transmission electron microscopy
This study was supported by the National Natural Science Foundation of China (grant 81171977 and 31500614) and China Postdoctoral Science Foundation (2014 M562598).
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