A novel phenanthroline-based colorimetric turn-off optical sensor for Zn2+

Odorant-responsive biological receptors and electronic noses for volatile organic compounds with aldehyde for human health and diseases: A perspective review

Volatile organic compounds (VOCs) are gaseous chemicals found in ambient air and exhaled breath. In particular, highly reactive aldehydes are frequently found in polluted air and have been linked to various diseases. Thus, extensive studies have been carried out to elucidate disease-specific aldehydes released from the body to develop potential biomarkers for diagnostic purposes. Mammals possess innate sensory systems, such as receptors and ion channels, to detect these VOCs and maintain physiological homeostasis. Recently, electronic biosensors such as the electronic nose have been developed for disease diagnosis. This review aims to present an overview of natural sensory receptors that can detect reactive aldehydes, as well as electronic noses that have the potential to diagnose certain diseases. In this regard, this review focuses on eight aldehydes that are well-defined as biomarkers in human health and disease. It offers insights into the biological aspects and technological advances in detecting aldehyde-containing VOCs. Therefore, this review will aid in understanding the role of aldehyde-containing VOCs in human health and disease and the technological advances for improved diagnosis.

A highly sensitive fluorescent sensor for fenamiphos detection in vegetable samples and living cells based-on an enzyme free system

Fenamiphos (Fena), an organophosphorous pesticide, is widely used in agricultural soils to control nematodes and thrips. This nematicide is harmful to fish, birds and humans and, causes several diseases. Therefore, the determination of the nematicide is crucial. Fena has been generally detected by enzyme-based systems which require specific conditions. Herein, we integrated a xanthene moiety and a pyrimidine moiety to obtain an enzyme-free detection system for Fena and, a fluorescent sensor (N-(6-(diethylamino)-9-(pyrimidin-5-yl)-3H-xanthen-3-ylidene)-N-ethylethanaminium hexafluorophosphate(V)) (RosPm) was easily prepared. The colorimetric and spectroscopic properties of RosPm were investigated using the UV-vis and fluorescence spectroscopy. RosPm exhibited a high selectivity and sensitivity to Fena over all the metal ions, the anions and pesticides tested in acetonitrile (ACN)/water (H₂O) (v:v, 1:1) solution. RosPm showed a clear visual change from purple to light-purple resulting fluorescent quenching with Fena. This sensor could be preferred for detecting Fena in vegetable samples such as tomato, pepper, and cucumber, and visualizing Fena in living MFC-7 cells.

A rapid responsive coumarin-naphthalene derivative for the detection of cyanide ions in cell culture

Cyanide ion (CN^-) is widely used in many industrial processes; however, it causes several diseases in humans. Therefore, rapid and accurate detection of CN^- is very important and urgent. In this study, a CN^- sensor (MH-2) which was capable of detecting CN^- ions in living cell was developed. MH-2 gives a rapid color change, absorbance and fluorescence response to CN^- in the presence of the anions tested in the working system. The binding ratio between the sensor and CN^- was demonstrated by some spectrophotometric methods and the sensing mechanism was investigated by NMR titration experiments, suggesting that MH-2 gives response to CN^- via the nucleophilic addition reaction. The fluorescence detection limit and the absorbance detection limit were calculated as 0.056 μM and 0.11 μM, respectively. Both of these detection limits are below the tolerable limit recommended by WHO for CN^- in the drinking water (1.9 μM). MH-2 was also applied to living cells for bio-imaging and the results showed that the sensor penetrates the cells and can detect cyanide ions in living cells.

A Review on Conducting Polymers for Colorimetric and Fluorescent Detection of Noble Metal Ions (Ag+, Pd2+, Pt2+/4+, and Au3+)

Conducting polymers (CPs) are conductive materials composed of organic polymers. CPs have excellent properties such as easy synthesis and effortless fabrication, tunable electrical property, high environmental stability, high mechanical and optical properties. These unique properties have attracted researchers to discover a wide variety of uses, such as batteries, solar cells, sensors, supercapacitors, electrochromic devices, and biochemical applications. Although CPs have many limitations in their pristine form, hybridization with other materials overcomes these limitations. Here in this review article, we discuss different CPs based chemosensors for colorimetric and fluorimetric detection and determination of noble metal ions (Ag+, Pd2+, Pt2+/4+, and Au3+) in different environmental, agricultural, and biological samples. Further, the sensing performances of these chemosensors have been compared and discussed. We hope this article will help the readers with the future design of CPs based optical sensor (colorimetric and fluorescent) for detecting noble metal cations.

A reaction-based system for the colorimetric detection of glyphosate in real samples

Glyphosate is widely used herbicides and causes several diseases in humans. Therefore, the detection of glyphosate is curial and urgent. Studies on the detection of glyphosate in literature are often based on inhibition of the enzyme acetylcholinesterase. In this study, we developed two simple colorimetric sensors, BP-Cl and CP-Cl, by linking 3-chloro-4-methylpyridine with 4-(dimethylamino)cinnamaldehyde or 4-(dimethylamino)benzaldehyde in a one-step reaction. The colorimetric and optical sensing properties of these compounds were investigated by the naked-eye and UV-Vis spectrophotometer in ACN/HEPES buffer (5 mM pH 8.0, 1:1 v/v). The sensors displayed high sensitivity and selectivity for glyphosate by color changes, which ranged from colorless to yellow for BP-Cl and yellow to orange for CP-Cl. The detection limits of BP-Cl and CP-Cl by the naked-eye detection were found as 15 µM and 10 µM. On the other hand, the detection limits of BP-Cl and CP-Cl via UV-Vis measurements were calculated as 0.847 µM and 1.23 µM, respectively. Moreover, the sensors were able to monitor glyphosate in water samples using the naked-eye, UV-Vis spectroscopy, and filter paper strips.