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 HQcontrolled 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.

Fluorescent MOF-based nanozymes for discrimination of phenylenediamine isomers and ratiometric sensing of o-phenylenediamine

Although peroxidase-like nanozymes have made great progress in bioanalysis,few current nanozymebased biosensors are constructed for discriminating isomers of organic compounds.Herein,fluorescent metal-organic framework(MOF)-based nanozyme is utilized for phenylenediamine isomers discrimination and detection.NH_(2)-MIL-101(Fe),as a member of Fe-based MOFs,functions as not only fluorescent indicator but also peroxidase mimics.In the presence of H_(2)O_(2),NH2-MIL-101(Fe) can catalyze the oxidation of o-phenylenediamine(OPD) and p-phenylenediamine(PPD) into their corresponding oxidation products(OPDox and PPDox),which in turn quench its intrinsic fluorescence at 445 nm via inner filter effect(IFE).Differently,a new fluorescence peak at 574 nm is observed for OPDox.Thus,a ratiometric fluorescence method for the detection of OPD can be designed with the fluorescence intensity ratio F_(574)/F_(445)as readout.This proposed strategy displays excellent discrimination ability for three phenylenediamines and may open new applications of MOFs in environmental science.

Ratiometric fluorescence detection of bleomycin based on proximity-dependent fluorescence conversion of DNA-templated silver nanoclusters

We design a ratiometric fluo rescent sensing platform for bleomycin(BLM) by using proximity-dependent DNA-templated silver nanoclusters(DNA-AgNCs) probe.This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore.The proposed strategy is based on the two following facts:(1) a covert DNA can approach and transform the DNA-AgNCs with green emission(G-DNA-AgNCs) into red emission through hybridization reaction.(2) The specific cleavage of the convert DNA by BLM in the presence of Fe(Ⅱ) inhibits the discoloration of G-DNA-AgNCs.Thus,benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs,a hignly-sensitive ratiometric sensor for BLM has been successfully developed.The detection limit is as low as 30 pmol/L.This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost.Moreover,this ratiometric method has been applied to the detection of BLM in human serum samples,illustrating a promising tool for analysis of BLM in cancer therapy.