ReviewRecent progress in fluorescent probes for detection of carbonyl species: Formaldehyde, carbon monoxide and phosgene☆
Introduction
Formaldehyde (FA), carbon monoxide (CO) and phosgene (COCl2), three of the most important types of carbonyl species, have attracted wide attention in the realm of science [1], [2], [3]. Formaldehyde, as the simplest aldehyde, is usually found in daily food (including meat, seafood, fruits and vegetables), because it is a widely used preservative. Formaldehyde has also been extensively applied in industry, for producing plastics, detergents, corrosion remover, wood processing, pharmaceuticals and so on [4], [5]. Notably, environmental formaldehyde is mainly produced from industrial activities, food preservatives and building materials. Environmental formaldehyde, as one of the omnipresent indoor air pollutants, easily causes DNA damage, lachrymation, emesia, sneezing, coughing, somnolence and stupor, Alzheimer's disease, and even death [6], [7], [8]. Based on the explicit evidence of formaldehyde detriment, it was categorized as a human carcinogen Group I by the International Agency for Research on Cancer (IARC) in 2004 [9]; it has also been ranked in the second control list of toxic fluorescents in China [10]. However, formaldehyde has recently been employed as a metabolic intermediate and an endogenously-produced carbonyl species, released in plenty of biological organisms via protein N-demethylation, DNA/RNA demethylation or metabolite demethylation (Fig. 1) [11]. For example, the concentration of formaldehyde is from 0.2 mmol to 0.4 mmol in a normal physiological brain. At this concentration, formaldehyde plays a crucial role in memory formation by the DNA demethylation cycle and cognitive ability [12], [13].
Carbon monoxide (CO) is mainly generated as an accessory substance in the incomplete combustion of gas, oil or solid fuels [14]. Recently, CO (similar to nitric oxide) has drawn wide attention in biological systems due to its cell-signaling and therapeutic role, although it has long been considered as a silent killer due to its lack of taste, color and odor [15], [16], [17]. The toxicity of CO is partly derived from its higher affinity than O2 for hemoglobin, causing death by asphyxiation. Both formaldehyde and CO are toxic at high concentrations but are extremely important at low levels as cell-signaling agents.
Carbonyl chloride (phosgene), with the chemical formula O = CCl2, is a well-known colorless and highly reactive gas. It has been widely used as a chemical intermediate in the industrial production of pesticides, isocyanate-based polymers, artificial foaming materials, dyes, rust-removal materials, plastics and pharmaceuticals [18], [19], [20]. However, phosgene is extremely toxic and was used as a chemical weapon during World War I [21], [22]. The toxicity of phosgene is mainly due to its highly reactive activity with proteins in the respiratory tract and lungs of human beings. Phosgene can cause pulmonary irritation, pulmonary emphysema, delayed pulmonary edema, pneumonia, respiratory distress and even death [23], [24]. Consequently, these carbonyl species (formaldehyde, carbon monoxide and phosgene) pose a serious threat to the environment and public health. In order to prevent the toxicity of formaldehyde, CO and phosgene to human health, it is highly crucial to detect the levels of these carbonyl species in the environment and in biological systems. Numerous methods have been developed for the design and detection of formaldehyde, CO and phosgene nowadays, such as electro-fluorescent biosensors, piezoelectric sensors, semiconductor sensors, colorimetric probes, quartz crystal microbalance, Raman spectroscopy, transmission electro-microscopy, gas chromatography, liquid chromatography and X-ray diffraction [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], but fluorescent probes, which rely on chemical reactions between the probes and the target, provoking a dramatic fluorescence change, often remain the most commonly employed method for detecting such important small molecules [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52]. For example, in 2015, a review paper by Chang’s group provided a good summary of the recent developments in fluorescent probes for molecular imaging and the detection of H2S in biological systems [51]. In 2016, Shin and Yoon’s group summarized the recent progress in the development of fluorescent probes for the detection of reactive oxygen and nitrogen species [52]. In 2018, Yoon’s group also summarized recent advances in the development of chromophore-based chemosensors for nerve agents and phosgene [3]. This review will cover the most significant developments in fluorescent probes for the detection of the carbonyl species formaldehyde, carbon monoxide and phosgene in recent years (typically the last 10 years), with a special emphasis on their mechanisms and applications. Additionally, special detection methods for formaldehyde, carbon monoxide or phosgene might be mentioned in this review [3], [11], [53], [54], [55], [56], [57], [58].
Section snippets
Fluorescent probes for detecting formaldehyde
Over the past decades, more and more reactive fluorescent probes have been designed, reported and applied in detecting formaldehyde. Almost all fluorescent probes are based on the chemical reactions of formaldehyde and the probe’s amino group. Three types of primary reaction mechanisms have been presented in Fig. 2. (a) The aza-Cope rearrangement reaction of the homoallylamino group and formaldehyde to produce an aldehyde or phenol, leading to variations of the fluorescence signal. (b) The
Fluorescent probes for carbon monoxide
A large number of methods, such as gas chromatography [124], [125], chromogenic detection [126], [127], [128], electrochemical assays [129], laser sensor-infrared absorption [130] and others [131], [132], [133], have been designed and developed for CO detection. However, these methods are restricted to the detection and imaging physiological CO concentrations in living cells. Recently, fluorescence sensing and imaging has become a useful and powerful technique to monitor CO levels in the air or
Fluorescent probes for phosgene
Due to the high toxicity of phosgene, a variety of selective and sensitive methods, such as gas chromatography [164], [165], electrochemical assays [166], enzyme, nanoparticles, surface acoustic wave sensors, carbon nanotubes and others have been developed for its detection [167], [168], [169], [170], [171], [172]. However, these methods are restricted by poor portability, high cost, low sensitivity and time-consuming procedures for phosgene detection. Nowadays, fluorescent-phosgene probes have
Conclusions and outlook
The design and synthesis of multifunctional fluorescent probes is fascinating, because it reveals a great richness of structural, physico-chemical and optical properties, as well as playing a significant role as chemical sensors. This review has focused on recent progress in fluorescent probes for the detection of the carbonyl species formaldehyde, carbon monoxide and phosgene. The properties of representative carbonyl species fluorescent probes published recently, which have been applied for
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
Invaluable contributions from talented students and colleagues cited in the references, and financial support from the National Natural Science Foundation of China (Grant Nos. 21805166 & 21606145), the 111 Project of Hubei Province (Grant No. 2018-19-1), Guangxi Key Laboratory of Chemistry and Engineering of Forest Products (GXFC17-18-04) and China Three Gorges University are gratefully acknowledged.
References (211)
- et al.
Sens. Actuators B
(2016) - et al.
Environ. Int.
(2009) - et al.
Sens. Actuators B.
(2017) - et al.
Talanta.
(2009) - et al.
Curr. Opin. Toxicol.
(2018) - et al.
Biochem. Biophys. Res. Commun.
(2011) - et al.
Curr. Opin. Chem. Biol.
(2017) - et al.
Toxicol. Lett.
(2016) - et al.
Talanta
(2000) - et al.
Talanta
(2002)
Carbohydr. Polym.
Sens. Actuators B
Talanta
Sens. Actuators B
Sens. Actuators B
J. Chromatogr. B
Chin. Chem. Lett.
Spectrochim. Acta A
Coord. Chem. Rev.
Coord. Chem. Rev.
Coord. Chem. Rev.
Coord. Chem. Rev.
Chin. Chem. Lett.
Coord. Chem. Rev.
Talanta
Sens. Actuators B
Front. Chem.
Chem. Sci.
Sens. Actuators B
Anal. Chim. Acta
Chem. Sci.
Sens. Actuators B
Org. Biomol. Chem.
Dyes Pigm.
Coord. Chem. Rev.
Coord. Chem. Rev.
Coord. Chem. Rev.
Tetrahedron Lett.
Talanta
Dyes Pigm.
Sens. Actuators B
Sens. Actuators B
Tetrahedron
Chem. Soc. Rev.
ACS Sens.
Environ. Mol. Mutagen.
Prog. Biochem. Biophys.
Chem. Res. Toxicol.
Sci. Rep.
Pharmacol. Rev.
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Dedicated to our distinguished friend and colleague Professor Dong-Sheng Li on the occasion of his 50th birthday.