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Chromo-Fluorogenic Detection of Soman and Its Simulant by Thiourea-Based Rhodamine Probe.

ABSTRACT: Here, we introduced a novel thiourea-based rhodamine compound as a chromo-fluorogenic indicator of nerve agent Soman and its simulant diethyl chlorophosphate (DCP). The synthesized probe N-(rhodamine B)-lactam-2-(4-cyanophenyl) thiourea (RB-CT), which has a rhodamine core linked by a cyanophenyl thiosemicarbazide group, enabled a rapidly and highly sensitive response to DCP with clear fluorescence and color changes. The detection limit was as low as 2 × 10-6 M. The sensing mechanism showed that opening of the spirolactam ring following the phosphorylation of thiosemicarbazides group formed a seven-membered heterocycle adduct, according to MS analysis and TD-DFT calculations. RB-CT exhibited high detecting selectivity for DCP, among other organophosphorus compounds. Moreover, two test kits were employed and successfully used to detect real nerve agent Soman in liquid and gas phase.

SUBMITTER: Li S

PROVIDER: S-EPMC6429212 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Project description:The synthesis of capped mesoporous silica nanoparticles (MSN) conjugated with an antibody (AB) as a gatekeeper has been carried out in order to obtain a delivery system able to release an entrapped cargo (dye) in the presence of a target molecule (antigen) to which the conjugated antibody binds selectively. In particular, MSN loaded with rhodamine B and functionalized on the external surface with a suitable derivative of N-(t-butyl)-3-oxo-(5α,17β)-4-aza-androst-1-ene-17-carboxamide (finasteride) have been prepared (S1). The addition of polyclonal antibodies against finasteride induced capping of the pores due to the interaction with the anchored hapten-like finasteride derivative to give a MSN-hapten-AB nanoparticle S1-AB. It was found that the addition of capped material S1-AB to water solutions containing finasteride resulted in displacement of the antibody, pore uncapping and entrapped-dye release. The response of the gated material is highly selective, and only finasteride, among other steroids, was able to induce a significant uncapping process. Compared with finasteride, the finasteride metabolite was able to release 17 % of the dye, whereas the exogen steroids testosterone, metenolone and 16-β-hydroxystanozolol only induced very little release of rhodamine B (lower than 10 %) from aqueous suspensions containing sensing solid S1-AB. A detection limit as low as 20 ppb was found for the fluorimetric detection of finasteride. In order to evaluate a possible application of the material for label-free detection of finasteride, the capped material was isolated and stored to give final sensing solid S1-AB-i. It was found to display a similar behavior towards finasteride as to that shown by freshly prepared S1-AB; even after a period of two months, no significant loss of selectivity or sensitivity was noted. Moreover, to study the application for the detection of finasteride in biological samples, this "aged" material, S1-AB-i, was tested using commercially available blank urine as matrix. Samples containing 70 and 90 % blank urine were spiked with a defined amount of finasteride, and the concentration was determined using capped S1-AB-i. Recovery ranges from 94 % to 118 % were reached.

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Chromo-Fluorogenic Detection of Soman and Its Simulant by Thiourea-Based Rhodamine Probe.

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