Epitope-Shared Hapten Enhancing Antibody Polyreactivity for Simultaneous Immunochromatography of Oxyphenisatin Adulterants.

Given the significant threat posed by oxyphenisatin adulterants (OPHs) in weight-loss foods, simultaneous analysis of the OPHs is necessary. Herein, four novel haptens based on the general epitope shared among the OPHs were raised by computer-aided chemical modeling prediction, with the expectation of eliciting antibody responses targeting three of the OPHs. One obtained monoclonal antibody (mAb) showed maximal half-inhibitory concentration (IC50) of 0.40-12.11 ng/mL for OPHs. The key interaction forces responsible for the corecognition of the OPHs were revealed by the intrinsic molecular mechanism. The developed immunochromatography (ICA) indicated a detection capability for screening (CCß) for OPHs estimated to be 5-600 ng/g in jelly, candy tablets, and oral liquid. Furthermore, the analysis of 15 real samples by our method showed a good correlation with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our research not only presented a rapid approach for identifying OPHs adulteration but also proposed an effective hapten prediction strategy to enhance antibody polyreactivity.

Rational construction of a new water soluble turn-on colorimetric and NIR fluorescent sensor for high selective Sec detection in Se-enriched foods and biosystems.

As a naturally occurring amino acid, selenocysteine (Sec) plays a key role in a variety of cellular functions and Se-enriched foods. In this work, a robust water soluble fluorescence turn-on near-infrared (NIR) sensor NIR-Sec was constructed for Sec detection over biothiols in Se-enriched foods. Specifically, NIR-Sec contains a readily prepared water soluble NIR dicyanoisophorone fluorophore and a well-known response-site 2,4-dinitrobenzenesulfonyl moiety with strong intramolecular charge transfer (ICT) effect to quench the fluorescence intensity of NIR fluorophore. Upon addition of Sec, the NIR dicyanoisophorone fluorophore was released and a bright red emission at 663 nm was observed. Moreover, NIR-Sec toward Sec exhibited rapid response time (∼1 min), a large stoke shift (183 nm), and high selectivity and sensitivity (LOD: 52 nM). Impressively, NIR-Sec was successfully employed to detect and image Sec in Se-enriched foods and shrimp, indicating NIR-Sec could provide a robust tool for investigating the role of Sec in complex real-food samples.

Molecular engineering-based a dual-responsive fluorescent sensor for sulfur dioxide and nitric oxide detecting in acid rain and its imaging studies in biosystems.

Sulfur dioxide (SO2) and nitric oxide (NO), known as sulfur oxides and nitrogen oxides, are toxic air pollutants and seriously threaten human health. Herein, for the first time, a robust dual-response fluorescent sensor CGT with two different emission fluorophores and dual well-known response-group for visual bisulphites (HSO3-) and nitrites (NO2-) detection was reported. Specifically, once CGT was incubated with HSO3- firstly, the color of the test solution changed to dark yellow with no-fluorescence emission, following added NO2-, the color of the test solution changed to yellow with a bright cyan emission. However, NO2- was added firstly, the color of the test solution changed to dark purple with a white emission, and then added HSO3-, the color of the test solution changed to yellow with a bright cyan emission. Furthermore, CGT showed high sensitivity and selectivity toward HSO3- and NO2- detecting with good detection limits as low as 20.17 nM and 4.14 nM, respectively. Impressively, CGT showed good detection capability in complex aqueous samples and was successfully used for the detection of HSO3- and NO2- in biosystems. Thus, the experimental results indicated CGT as a powerful novel visual detecting tool for HSO3- and NO2- detecting in complex acid rain and biosystems.

Double-site-based a smart fluorescent sensor for logical detecting of sulphides and its imaging evaluation of living organisms.

Thiophenol and hydrosulphite are a group of toxic environmental pollutants, which contaminate land, water and food exhibiting a serious risk to human health. Herein, we reported a xanthene dye-based sensor (DSF) with dual well-known response sites for visual detecting PhSH and HSO3-. Specifically, when DSF reacted with PhSH firstly, the color of the solution changed to blue with bright red fluorescence emission. After added with HSO3-, the color of the solution became yellow, and emitted yellow fluorescence signal. However, DSF was first added with HSO3-, the color of the solution changed to purple with no-fluorescence emission, and then PhSH was added, the color of the solution changed to yellow with a bright yellow fluorescence. Notably, DSF exhibited high sensitivity and selectivity for PhSH and HSO3- detection with a very low detection limits of 2.27 nM and 22.91 nM, respectively. More importantly, DSF could detect PhSH and HSO3- in water, real-food and biological systems. Therefore, the experimental results showed DSF as a robust new logical monitoring tool for the detection of PhSH and HSO3- in water, real-food samples and biological systems.

Rational Development of a New Reaction-Based Ratiometric Fluorescent Probe with a Large Stokes Shift for Selective Detection of Bisulfite in Tap Water, Real Food Samples, Onion Tissues, and Zebrafish.

Bisulfite (HSO3-) is usually widely added to tap water and food because it has antibacterial, bleaching, and antioxidant effects. However, its abnormal addition would cause a series of serious diseases related to it. Therefore, development of an effective method for HSO3- detection was of great significance to human health. In this work, a new reaction-based ratiometric fluorescent probe KQ-SO2 was rationally designed, which could be used for the highly selective detection of HSO3- in tap water, real food samples, onion tissues, and zebrafish. Specifically, a positively charged benzo[e]indolium moiety and a carbazole group through a condensation reaction resulted in KQ-SO2, which displayed two well-resolved emission bands separated by 225 nm, fast response (1 min), and high selectivity and sensitivity toward HSO3- upon undergoing the Michael addition reaction, as well as low cytotoxicity in vitro. In addition, KQ-SO2 has been successfully applied for the detection of HSO3- in tap water, real food samples, onion tissues, and zebrafish with satisfactory results. We predict that KQ-SO2 could be used as a powerful tool to reveal the relationship between HSO3- and the human health.

A novel fluorescent probe for ratiometric detection of formaldehyde in real food samples, living tissues and zebrafish.

Herein, a two-photon (TP) ratiometric fluorescent probe (NpFA) was developed for detecting formaldehyde (FA) in real food samples, living onion tissues and zebrafish by fluorescence resonance energy transfer (FRET) strategy. Specifically, a TP fluorophore as the donor and a FA turn-on naphthalimide fluorophore as the acceptor were connected by a non-conjugated linker to construct the TP-FRET-based NpFA, which exhibited a target-modulated ratiometric fluorescence response to FA rapidly with high selectivity and sensitivity during 65 s, and a large ratio ~5-fold enhancement at I550/I410 after addition of FA, displaying ~60-fold enhancement at 550 nm and a quite low DOC of 5.8 ± 0.2 nM. Moreover, NpFA has a good imaging resolution and depth of deep tissue penetration. Therefore, based on the above results, NpFA has the capability to be a useful tool for investigating FA in real samples application, and we also hope NpFA will further study of the physiological and pathological function of FA.

TP-FRET-Based Fluorescent Sensor for Ratiometric Detection of Formaldehyde in Real Food Samples, Living Cells, Tissues, and Zebrafish.

Formaldehyde (FA, HCHO) is a highly reactive carbonyl species, which is very harmful to humans and the environment as a tissue fixative and preservative. Therefore, developing some highly sensitive, selective, and rapid detection methods is significant for human health in food safety and environmental protection. Herein, a two-photon (TP) ratiometric sensor, CmNp-CHO, has been constructed by conjugating a TP donor (Π-push-pull-structure) with a FA off-on acceptor (functioned with hydrazide moiety) via a nonconjugated linker through the fluorescence resonance energy transfer mechanism. Such a scaffold affords CmNp-CHO a reliable and specific probe for detecting FA with two well-resolved emission peaks separated by 124 nm. Also, it responds to FA rapidly with high selectivity and sensitivity during 1.0 min and a large ratio enhancement at I550/I426 with addition of 0-20µM FA, exhibiting ∼4-fold ratio increase and a fairly low LOD of 8.3 ± 0.3 nM. Moreover, CmNp-CHO has been successfully employed for detecting FA in live cells, onion tissues, and zebrafish, exhibiting that CmNp-CHO can serve as a useful tool for investigating FA in real food application and offering strong theoretical support and technical means for investigation of physiological and pathological functions of FA.