In situ formation of fluorescent silicon-containing polymer dots for alkaline phosphatase activity detection and immunoassay

The discovery and application of analyte-triggered fluorophore generation or fluorogenic reaction are significant and beneficial to the development of novel fluorescence (FL) analysis method. In this study, for the first time, we have reported a fluorogenic reaction to prepare fluorescent silicon-containing polymer dots (Si-PDs) by simply mixing N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAMO) and hydroquinone (HQ) in aqueous solution at ambient temperature. Inspired by the alkaline phosphatase (ALP)-catalyzed hydrolysis of the substrate sodium 4-hydroxyphenyl phosphate (4-HPP) into HQ and the resultant HQ-controlled intense green Si-PDs generation, we have established a straightforward ALP activity assay by innovatively employing commercially available 4-HPP as the substrate. More significantly, the specific preparation method, clear formation mechanism and excellent performance enable the Si-PDs as well as its generation process to develop facile and attractive FL immunoassay. With the help of the universal ALP-based enzyme-linked immunosorbent assay (ELISA) platform and corresponding antibody, a convenient and conceptual ALP-based fluorescent ELISA has been constructed and applied in sensing cardiac troponin I (cTnI), a well-known biomarker of acute myocardial infarction. Our research via in situ formation of fluorescent nanomaterials has great potential application in ALP activity assay, inhibitor screening, and disease diagnosis.