Recent Advances in the Application of Nitro(het)aromatic Compounds for Treating and/or Fluorescent Imaging of Tumor Hypoxia.

This review delves into recent advancements in the field of nitro(het)aromatic bioreductive agents tailored for hypoxic environments. These compounds are designed to exploit the low-oxygen conditions typically found in solid tumors, making them promising candidates for targeted cancer therapies. Initially, this review focused on their role as gene-directed enzyme prodrugs, which are inert until activated by specific enzymes within tumor cells. Upon activation, these prodrugs undergo chemical transformations that convert them into potent cytotoxic agents, selectively targeting cancerous tissue while sparing healthy cells. Additionally, this review discusses recent developments in prodrug conjugates containing nitro(het)aromatic moieties, designed to activate under low-oxygen conditions within tumors. This approach enhances their efficacy and specificity in cancer treatment. Furthermore, this review covers innovative research on using nitro(het)aromatic compounds as fluorescent probes for imaging hypoxic tumors. These probes enable non-invasive visualization of low-oxygen regions within tumors, providing valuable insights for the diagnosis, treatment planning, and monitoring of therapeutic responses. We hope this review will inspire researchers to design and synthesize improved compounds for selective cancer treatment and early diagnostics.

Porous Pd-loaded IRMOF-9 as Highly Efficient Recyclable Material towards the Reduction of Nitroaromatics in Aqueous Media.

Nitroaromatic compounds (NACs) cause severe hazardous impacts on human health as well as on the environment. Therefore, there is dire need to develop a robust material to reduce the toxicity of these organic pollutants. In this regard, our group developed a series of porous MOF materials viz., Pdx@IRMOF-9 (x=2%, 5% and 10%) by loading different concentration of Pd(II) on IRMOF-9 and explored them towards reduction of different nitroaromatic compounds. Pd10%@IRMOF-9 showed ~30% greater efficiency for the reduction of 4-NP as compared to Pd2%@IRMOF-9. Pd10%@IRMOF-9 showed excellent reduction ability (>85%) towards 4-NP, 2-NP, 2-NA, 3-NA and 2,4-DNPH. The kinetic studies indicates that the reduction follows the pseudo-first-order kinetics. Moreover, the rate constant value for reduction of 3-NA was ~9 times higher than that of 2-NP. Based on the kinetic parameters, the t1/2 values for all the nitroaromatics have been calculated. The kinetic parameters, Km and Vmax have been calculated from double reciprocal Lineweaver-Burk plot and found 65.984 µM and 116 x10-6 Mmin-1 respectively. Pd10%@IRMOF-9 showed excellent recyclability towards the reduction of 4-NP for few consecutive cycles without any remarkable loss in its activity. Thus, highly efficient, porous and robust material for reduction of nitroaromatic compounds in aqueous media have been demonstrated.

Characterization of atmospheric nitroaromatic compounds in Southwest China by direct injection liquid chromatography-tandem mass spectrometry analysis of aerosol extracts.

Nitroaromatic compounds (NACs) in ambient particles are of great concern due to their adverse effects on human health and climate. However, investigations on the characteristics and potential sources of NACs in Southwest China are still scarce. In this study, a field sampling campaign was carried out in the winter of 2022 at a suburban site in Mianyang, Southwest China. A direct injection liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to rapidly determine 10 NACs in fine particulate matter (PM2.5) extracts. The method was sensitive for the quantification of the NACs, with a limit of quantification (LOQ) in the range of 0.092-0.52 ng mL-1. Then, the developed method was applied to determine the concentrations of nitrophenols (NPs), nitrocatechols (NCs), nitrosalicylic acids (NSAs), and nitronaphthol in PM2.5 in Mianyang. The average concentration of total NACs was 78.2 ± 31.2 ng m-3, with daily concentrations ranging from 20.7 to 127.9 ng m-3. Among the measured NACs, 4-nitrocatechol was the most abundant, accounting for 57.8% of the NACs in winter. The five NPs compounds together contributed to 14% of the NACs, which was lower than in other Chinese cities due to the warm climate in winter in Southwest China. NSAs and nitronaphthol each accounted for less than 5% of the NACs. Three major sources of NACs were identified based on the principal component analysis, including vehicle emissions, biomass burning, and secondary formation. The significant correlation between individual NACs and NO2 supported their secondary formation sources. The good correlation between NPs and cloud amount further suggested that gas-phase oxidation was the possible NPs formation mechanism. Our findings revealed the important role of nitrocatechols in NACs in Southwest China, implying that more measures should be taken to control biomass burning and aromatic volatile organic compounds emissions to reduce the level of NACs.

Utilizing excited-state proton transfer fluorescence quenching mechanism, layered rare earth hydroxides enable ultra-sensitive detection of nitroaromatic.

Convenient, rapid, and accurate detection of nitroaromatic organic toxins and harmful substances is of great significance in research. In the present study, two-dimensional layered rare-earth hydroxides (LYH) were used as ion-exchange matrix materials, and the anionic fluorescent dye molecules (HPTS) were successfully introduced into the LYH structures in situ via a simple and effective "plug-and-play" strategy, which gave the compounds ultra-sensitive fluorescence sensing detection of nitrobenzene, p-nitrotoluene and p-nitrophenol (Fluorescence response time < 1 sec, and the LOD for nitrobenzene, p-nitrophenol and p-nitrotoluene reached an impressive 349 ppb, 22 ppb and 98 ppb, respectively). Combined with theoretical calculations, we elucidated in detail the fluorescence quenching response mechanism of the LYH-HPTS towards nitroaromatic. Additionally, we also constructed fluorescent paper sensor, which effectively transformed the LYH-HPTS from theoretical detection to device application. The LYH-HPTS material is not only simple to synthesize, cost-effective and stable, but also has the features of fast response, excellent sensitivity and selectivity, and good reproducibility, which provides a new approach for the rapid and accurate detection of nitroaromatic.

DprE1 and Ddn as promising therapeutic targets in the development of novel anti-tuberculosis nitroaromatic drugs.

Tuberculosis remains the second deadliest infectious disease in humans and a public health threat due to the emergence of multidrug-resistant (MDR-TB) and extensively drug-resistant (XDR-TB) strains. Therefore, it is urgent to identify new anti-tuberculosis treatments and novel therapeutic targets to prevent the emergence of resistance. In recent years, the study of anti-tuberculosis properties of nitroaromatic compounds has led to the identification of two novel biological targets, the deazaflavin (F420)-dependent nitroreductase Ddn and the decaprenylphosphoryl-ß-d-ribose 2'-epimerase DprE1. This review aims to show why Ddn and DprE1 are promising therapeutic targets and highlight nitroaromatic compounds interest in developing new anti-tuberculosis treatments active against MDR-TB and XDR-TB. Despite renewed interest in the development of new anti-tuberculosis nitroaromatic compounds, pharmaceutical companies often exclude nitro-containing molecules from their drug discovery programs because of their toxic and mutagenic potential. This exclusion results in missed opportunities to identify new nitroaromatic compounds and promising therapeutic targets.

Metal-organic frame material encapsulated Rhodamine 6G: A highly sensitive fluorescence sensing platform for the detection of picric acid contaminants in water.

As a water pollutant with excellent solubility, 2,4,6-trinitrophenol (also known as picric acid, PA) poses a potential threat to the natural environment and human health, so it is crucial important to detect PA in water. In this study, a novel composite material (MIL-53(Al)@R6G) was successfully synthesized by encapsulating Rhodamine 6G into a metal-organic frame material, which was used for fluorescence detection of picric acid (PA) in water. The composite exhibits bright yellow fluorescence emission with a fluorescence quantum yield of 58.23 %. In the process of PA detection, the composite has excellent selectivity and anti-interference performance, and PA can significantly quench the fluorescence intensity of MIL-53(Al)@R6G. MIL-53(Al)@R6G has the advantages of fast detection time (20 s), wide linear range (1-100 µM) and low detection limit (4.8 nM). In addition, MIL-53(Al)@R6G has demonstrated its potential for the detection of PA in environmental water samples with satisfactory results.

Insight into the mechanism of chlorinated nitroaromatic compounds anaerobic reduction with mackinawite (FeS) nanoparticles.

Anaerobic biotechnology for wastewaters treatment can nowadays be considered as state of the art methods. Nonetheless, this technology exhibits certain inherent limitations when employed for industrial wastewater treatment, encompassing elevated substrate consumption, diminished electron transfer efficiency, and compromised system stability. To address the above issues, increasing interest is being given to the potential of using conductive non-biological materials, e,g., iron sulfide (FeS), as a readily accessible electron donor and electron shuttle in the biological decontamination process. In this study, Mackinawite nanoparticles (FeS NPs) were studied for their ability to serve as electron donors for p-chloronitrobenzene (p-CNB) anaerobic reduction within a coupled system. This coupled system achieved an impressive p-CNB removal efficiency of 78.3 ± 2.9% at a FeS NPs dosage of 1 mg/L, surpassing the efficiencies of 62.1 ± 1.5% of abiotic and 30.6 ± 1.6% of biotic control systems, respectively. Notably, the coupled system exhibited exclusive formation of aniline (AN), indicating the partial dechlorination of p-CNB. The improvements observed in the coupled system were attributed to the increased activity in the electron transport system (ETS), which enhanced the sludge conductivity and nitroaromatic reductases activity. The analysis of equivalent electron donors confirmed that the S2- ions dominated the anaerobic reduction of p-CNB in the coupled system. However, the anaerobic reduction of p-CNB would be adversely inhibited when the FeS NPs dosage exceeded 5 g/L. In a continuous operation, the p-CNB concentration and HRT were optimized as 125 mg/L and 40 h, respectively, resulting in an outstanding p-CNB removal efficiency exceeding 94.0% after 160 days. During the anaerobic reduction process, as contributed by the predominant bacterium of Thiobacillus with a 6.6% relative abundance, a mass of p-chloroaniline (p-CAN) and AN were generated. Additionally, Desulfomonile was emerged with abundances ranging from 0.3 to 0.7%, which was also beneficial for the reduction of p-CNB to AN. The long-term stable performance of the coupled system highlighted that anaerobic technology mediated by FeS NPs has a promising potential for the treatment of wastewater containing chlorinated nitroaromatic compounds, especially without the aid of organic co-substrates.

Efficient nanostructured Cs2CuBr2Cl2 perovskite as a fluorescent sensor for the selective "Switch Off" detection of nitrobenzene.

Lead halide nanostructured perovskites are well known for their excellent photoluminescence and optoelectronic properties. However, lead toxicity and instability in moisture impedes its suitability for material use. Here we synthesized a highly efficient, lead free, economical, stable Cs2CuBr2Cl2 perovskite nanocrystals (PNCs) via Ligand Assisted Re-Precipitation (LARP) method which is less explored. The sensing application of the synthesized PNCs towards nitro explosives and other small organic compounds were studied. The probe exhibited high selectivity towards nitrobenzene with a lowest detection limit of 57.64 nM. The fluorescent emission intensity was drastically quenched upon the addition of 32 µM nitrobenzene. A Stern-Volmer plot was utilized for the quantification of fluorescence quenching. Further to investigate the quenching mechanism, time correlated single photon counting spectroscopy and other photoluminescence studies were performed pointing out the possibility of fluorescence resonance energy transfer. The work has been further extended to test the capability of the probe to detect nitrobenzene in real water samples and a good recovery percentage ranging from 93-98 % was obtained. Further, a paper strip assay was designed which successfully detected nitrobenzene and can be clearly noticed even with our naked eye making the probe an excellent sensor for nitrobenzene detection.

Aggregation-induced emission enhancement (AIEE) active bispyrene-based fluorescent probe: "turn-off" fluorescence for the detection of nitroaromatics.

The detection of nitroaromatic explosives in real samples is essential for environmental monitoring because of their strongly powerful nature and wide applications in industries. Aggregation-induced emission enhancement (AIEE) active fluorescent probe has been widely employed to detect nitroaromatic explosives. Hereby, a simple V-shaped bispyrene-based fluorescent probe (called py-o) with AIEE properties was designed and synthesized, which was fully charactered by 1D NMR, ESI, FTIR, and 2D NOESY spectra. The py-o displayed bright blue-green fluorescence excimer emission at 480 nm in DMF/H2O (v/v 1:1). It is observed that the fluorescence excimer emission of py-o at 480 nm was quenched by PA in solution with a quenching constant of 5.45 × 104 M-1, and the limit of detection was approximately 0.139 µM. The details of the sensing mechanism were explained using 1H NMR titrations, Job's plot and Bensi-Hildebrand methods, which revealed a 1:1 binding ratio via the π-π interactions between PA and py-o. Meanwhile, it exhibited outstanding anti-interference ability in the detection of PA when interfering analytes were added under the same conditions. Furthermore, low-cost thin-layer chromatography (TLC) plates coated with py-o were developed as fluorescent tools for naked-eye detection of PA in the solid state. Therefore, this work provides a new method for constructing an AIEE fluorescent probe for the detection of nitroaromatic explosives to utilize in environmental monitoring.

The Catalysis Mechanism of E. coli Nitroreductase A, a Candidate for Gene-Directed Prodrug Therapy: Potentiometric and Substrate Specificity Studies.

E. coli nitroreductase A (NfsA) is a candidate for gene-directed prodrug cancer therapy using bioreductively activated nitroaromatic compounds (ArNO2). In this work, we determined the standard redox potential of FMN of NfsA to be -215 ± 5 mV at pH 7.0. FMN semiquinone was not formed during 5-deazaflavin-sensitized NfsA photoreduction. This determines the two-electron character of the reduction of ArNO2 and quinones (Q). In parallel, we characterized the oxidant specificity of NfsA with an emphasis on its structure. Except for negative outliers nitracrine and SN-36506, the reactivity of ArNO2 increases with their electron affinity (single-electron reduction potential, E17) and is unaffected by their lipophilicity and Van der Waals volume up to 386 Å. The reactivity of quinoidal oxidants is not clearly dependent on E17, but 2-hydroxy-1,4-naphthoquinones were identified as positive outliers and a number of compounds with diverse structures as negative outliers. 2-Hydroxy-1,4-naphthoquinones are characterized by the most positive reaction activation entropy and the negative outlier tetramethyl-1,4-benzoquinone by the most negative. Computer modelling data showed that the formation of H bonds with Arg15, Arg133, and Ser40, plays a major role in the binding of oxidants to reduced NfsA, while the role of the π-π interaction of their aromatic structures is less significant. Typically, the calculated hydride-transfer distances during ArNO2 reduction are smallwer than for Q. This explains the lower reactivity of quinones. Another factor that slows down the reduction is the presence of positively charged aliphatic substituents.

Characteristics and source apportionment of water-soluble organic nitrogen (WSON) in PM2.5 in Hong Kong: With focus on amines, urea, and nitroaromatic compounds.

Water-soluble organic nitrogen (WSON) is ubiquitous in fine particulate matter (PM2.5) and poses health and environmental risks. However, there is limited knowledge regarding its comprehensive speciation and source-specific contributions. Here, we conducted chemical characterization and source apportionment of WSON in 65 PM2.5 samples collected in Hong Kong during a 1-yr period. Using various mass-spectrometry-based techniques, we quantified 22 nitrogen-containing organic compounds (NOCs), including 17 nitroaromatics (NACs), four amines, and urea. The most abundant amine and NACs were dimethylamine and 4-nitrocatechol, respectively. Two secondary (i.e., secondary formation and secondary nitrate) and five primary sources (i.e., sea salt, fugitive dust, marine vessels, vehicle exhaust, and biomass burning) of WSON and these three categories of NOCs were identified. Throughout the year, secondary sources dominated WSON formation (69.0%), while primary emissions had significant contributions to NACs (77.1%), amines (75.9%), and urea (83.7%). Fugitive dust was the leading source of amines and urea, while biomass burning was the main source of NACs. Our multi-linear regression analysis revealed the significant role of sulfate, NO3, nitrate, liquid water content, and particle pH on WSON formation, highlighting the importance of nighttime NO3 processing and heterogeneous and aqueous-phase formation of NOCs in the Hong Kong atmosphere.

Fabrication of nano-sized Pd catalyst supported on sodium carboxymethyl cellulose/gum Arabic/sodium alginate functionalized microspheres for catalytic reduction of nitro compounds, organic dyes, K3[Fe(CN)6], and chromium(VI) pollutants.

The rapid development of industrialization and urbanization, along with the increasing human population, has led to serious water pollution. Among water pollutants, organic and inorganic pollutants cause serious problems for both the environment and human health due to their toxicity and carcinogenic properties. One of the best ways to eliminate these pollutants is to develop eco-friendly, efficient, and long-life catalysts. For this purpose, in this study, environmentally friendly microspheres containing sodium alginate (SA), sodium carboxymethyl cellulose (Na-CMC), and gum Arabic (GA) were fabricated as potential stabilizers (SA/Na-CMC/GA). Subsequently, newly heterogeneous catalyst system was designed by immobilizing Pd nanoparticles on them and characterized (Pd@SA/Na-CMC/GA). The catalytic reduction ability of Pd@SA/Na-CMC/GA was then investigated against the reduction of 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA), 4-nitro-o-phenylenediamine (4-NPDA), methylene blue (MB), methyl orange (MO), Rodamin B (RhB), potassium hexacyanoferrate(III) (K3[Fe(CN)6]), and hexavalent chromium (Cr(VI)) using NaBH4. The Pd@SA/Na-CMC/GA effectively catalyzed these contaminants in a short period of time under mild reaction conditions. As a result of the performed kinetics studies, rate constants were found to be 0.009 s-1, 0.016 s-1, 0.027 s-1, 0.018 s-1, 0.043 s-1, 0.058 s-1, 0.038 s-1 and 0.041 s-1 for the reduction of 4-NP, 2-NA, 4-NA, 4-NPDA, MO, RhB, K3[Fe(CN)6], and Cr(VI), respectively. Additionally, MO was immediately reduced by Pd@SA/Na-CMC/GA. The microsphere nature of Pd@SA/Na-CMC/GA allowed for easy recovery through simple filtration and successful reuse for up to six cycles.

Discovery of a nitroaromatic nannocystin with potent in vivo anticancer activity against colorectal cancer by targeting AKT1.

The development of targeted chemotherapeutic agents against colorectal cancer (CRC), one of the most common cancers with a high mortality rate, is in a constant need. Nannocystins are a family of myxobacterial secondary metabolites featuring a 21-membered depsipeptide ring. The in vitro anti-CRC activity of natural and synthetic nannocystins was well documented, but little is known about their in vivo efficacy and if positive, the underlying mechanism of action. In this study we synthesized a nitroaromatic nannocystin through improved preparation of a key fragment, and characterized its in vitro activity and in vivo efficacy against CRC. We first described the total synthesis of compounds 2-4 featuring Heck macrocyclization to forge their 21-membered macrocycle. In a panel of 7 cancer cell lines from different tissues, compound 4 inhibited the cell viability with IC values of 1-6 nM. In particular, compound 4 (1, 2, 4 nM) inhibited the proliferation of CRC cell lines (HCT8, HCT116 and LoVo) in both concentration and time dependent manners. Furthermore, compound 4 concentration-dependently inhibited the colony formation and migration of CRC cell lines. Moreover, compound 4 induced cell cycle arrest at sub-G1 phase, apoptosis and cellular senescence in CRC cell lines. In three patient-derived CRC organoids, compound 4 inhibited the PDO with IC values of 3.68, 28.93 and 11.81 nM, respectively. In a patient-derived xenograft mouse model, injection of compound 4 (4, 8 mg/kg, i.p.) every other day for 12 times dose-dependently inhibited the tumor growth without significant change in body weight. We conducted RNA-sequencing, molecular docking and cellular thermal shift assay to elucidate the anti-CRC mechanisms of compound 4, and revealed that it exerted its anti-CRC effect at least in part by targeting AKT1.

Colloidal Quantum Dots for Explosive Detection: Trends and Perspectives.

Sensitive, accurate, and reliable detection of explosives has become one of the major needs for international security and environmental protection. Colloidal quantum dots, because of their unique chemical, optical, and electrical properties, as well as easy synthesis route and functionalization, have demonstrated high potential to meet the requirements for the development of suitable sensors, boosting the research in the field of explosive detection. Here, we critically review the most relevant research works, highlighting three different mechanisms for explosive detection based on colloidal quantum dots, namely photoluminescence, electrochemical, and chemoresistive sensing. We provide a comprehensive overview and an extensive discussion and comparison in terms of the most relevant sensor parameters. We highlight advantages, limitations, and challenges of quantum dot-based explosive sensors and outline future research directions for the advancement of knowledge in this surging research field.

[Simultaneous determination of six nitroaromatic compounds and three anions in environmental matrices using a liquid chromatography-ion chromatography coupled system].

Nitroaromatic compounds are used extensively in various fields such as dyes, pesticides, spices, pharmaceuticals, and explosives. However, the residual raw materials of these compounds accumulate in the environment and pose serious risks to human health. Chronic exposure to low concentrations of nitroaromatic compounds can cause anemia, cancer, and organ damage. Currently, Fenton oxidation and natural bioremediation are the processes most often used to eliminate nitroaromatic compounds from environmental water and soil. According to previous research, the presence of inorganic anions such as chloride, nitrite, and nitrate ions in the environmental matrix exerts an inhibitory effect on the biodegradation of nitroaromatic compounds. Furthermore, high nitrate levels in drinking water can lead to the production of nitrosamine carcinogens, which affect ecological safety and human health, in water bodies. Thus, the simultaneous determination of nitroaromatic compounds and chloride, nitrite, and nitrate ions in environmental soil and water matrices is critical for selecting appropriate nitroaromatic compound degradation methods and monitoring surface water quality. Traditional detection methods require two sample pretreatment steps and two instrumental analytical techniques to determine nitroaromatic compounds and inorganic anions in environmental matrices; moreover, these methods are time consuming, labor intensive, and error prone. Therefore, in this study, a method that combines high performance liquid chromatography (HPLC) and ion chromatography (IC) was developed to simultaneously detect nitroaromatic compounds and anions in environmental matrices. In this method, sample enrichment was achieved through bulk injection and enrichment column collection, which greatly simplified the pretreatment process. The HPLC instrument was connected to the IC instrument using two six-way valves and an enrichment column. The system operation can be divided into four stages: (A) sample loading to the quantitative ring, (B) separation of nitroaromatic compounds and anions, (C) enrichment of anions in an AG20 column, and (D) simultaneous determination of nitroaromatic compounds and anions by HPLC and IC, respectively. The time of the anions flowing out of the C18 column was determined by directly connecting the C18 column to a conductivity detector. Based on the retention times of the anions, the switching time of the six-way valve was optimized to ensure that the anions completely entered the IC column, thereby ensuring the accuracy of the method. During the chromatographic analysis stage, nitroaromatic compounds were separated and analyzed by HPLC system with a mobile phase composed of potassium phosphate buffer (pH 7.0) and acetonitrile (60∶40, v/v) at a flow rate of 1.0 mL/min; in the IC system, the anions were separated and analyzed using a 20 mmol/L sodium hydroxide aqueous solution as the mobile phase under a suppression current of 50 mA. Both anions and nitroaromatic compounds exhibited strong linear correlations within certain concentration ranges, with correlation coefficients greater than 0.993. The recoveries of the nitroaromatic compounds and anions ranged from 88.20% to 105.38% at three spiked levels, with relative standard deviations ranging from 2.0% to 11.5%. The contents of six nitroaromatic compounds and three anions in five surface water and five soil samples were determined using the developed method. Although no nitroaromatic compounds were detected in these samples, the three anions were detected at contents ranging from 0.41 to 55.3 mg/L in surface water samples, and 0.56 to 30.2 mg/kg in soil samples. Methodological validation and actual sample detection demonstrated that the proposed method has a high degree of automation, simple operation, good repeatability, high accuracy, wide applicability, and high sensitivity. Thus, this method is suitable for the rapid determination of chloride, nitrite, nitrate ions and nitroaromatic compounds in soil and water and can be extended to the simultaneous determination of inorganic ions and organic matters in other samples.

Anthracene and tetraphenylsilane based conjugated porous polymer nanoparticles for sensitive detection of nitroaromatics in water.

Conjugated porous polymers (CPPs) are a kind of promising sensing materials for the detection of nitroaromatic compounds, but their sensing applications in aqueous media are limited because of their poor dispersity or solubility in water. In this study, we prepared anthracene and tetraphenylsilane based CPPs named PSiAn by conventional Suzuki coupling and Suzuki-miniemulsion polymerization, respectively. The structure, morphology and porosity of the CPPs were characterized by Fourier Transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), transmission electron microscope (TEM) and N2 sorption isotherm, respectively. Both of the CPPs have porous structure which is beneficial for the adsorption and diffusion of the analytes within them. The particle size of PSiAn nanoparticles prepared by Suzuki-miniemulsion polymerization is 10-40 nm from the TEM image, which facilitates the dispersion in the aqueous phase. Combined with the porosity and nanoparticle morphology, PSiAn nanoparticles realized the efficient photoluminescence (PL) sensing of nitroaromatic explosives in aqueous phase. The limit of detection (LOD) and limit of quantitation (LOQ) of PSiAn nanoparticles for 2,4,6-trinitrophenol (TNP) detection in the pure aqueous phase are 0.33 µM and 1.11 µM, respectively. Meanwhile, the good selectivity and anti-interference in presence of other nitro-compounds were observed. Furthermore, the spike/recovery test for the TNP detection in real water samples by PL sensing based on PSiAn nanoparticles indicates the quantitative recovery of TNP from 100.74 % to 101.00 %. The electrochemical test, ultraviolet-visible absorption spectra, excitation and emission spectra, and time-resolved PL spectra were investigated to explore the PL sensing mechanism. As a result, it is found that the fluorescence inner filter effect might be the predominant quenching mechanism during the detection of nitrophenolic compounds such as TNP and 4-nitrophenol (4-NP).

Synthesis of High-Fluorescent Diphenyl-anthracene Derivatives and Application in Detection of Nitroaromatic Explosives and Fingerprint Identification.

The development of high-intensity fluorescent materials is always the focuses and forefront projects because of their important applications in displays, sensing and detection fields. In recent years, the detection of explosives has attracted increasing attention due to security and counterterrorism issues. Herein, two diphenyl-anthracene (DPA) derivatives were designed and synthesized by introducing strong electron withdrawing fluorine atoms and cyano-groups to DPA, which exhibited strong fluorescence both in the solution and solid phase with the absolute quantum yields up to 70.4 % and 45.9 % respectively. The detection behavior of nitroaromatic explosives such as picric acid (PA), 2,4,6-trinitrotoluene (TNT) and 3-Nitropropionic acid (3-NP) also shows good sensitivity with the quenching constant as high as 6.3×104  L mol-1 . Theoretical calculation demonstrates that the fluorescence quenching behavior of the two DPA derivatives is caused by the behavior of photoinduced electron transfer (PET) and the resonance energy transfer (RET) studies explained the higher sensitivity and selectivity of both compounds towards PA than other nitro-containing explosives. Furthermore, the strong solid-state fluorescence of the DPA derivatives also shows excellent advantages in enhancing latent fingerprint recognition.

[Chemical Composition and Characterization of Nitroaromatic Compounds in Urban Areas of Shanghai].

The compositional characteristics, concentration of nitroaromatic compounds(NACs) in PM2.5 in urban Shanghai, and their correlation with gaseous precursors were investigated. A total of 39 winter and 46 summer PM2.5 samples from 2020 to 2021 were collected using a high-flow sampler and analyzed via ultra-performance liquid chromatography coupled with ESI-Orbitrap high-resolution mass spectrometry(UPLC-Orbitrap-HRMS). Quantitative analysis was performed on 12 NACs compounds, combined with backward trajectory meteorological elements, molecular composition, and classification analysis of CHON substances. The results showed that a total of 12 NACs had an average concentration in winter of 17.1 ng·m-3, which was three times higher than that in summer(5.7 ng·m-3), mainly due to air masses in winter coming primarily from the northern part of China with more biomass burning, whereas more air masses in summer came from the cleaner southeastern ocean. 4-Nitrophenol was the most abundant species of NACs in winter, whereas 4-nitrophenol(clean days) and 4-hydroxy-3-nitrobenzoic acid(polluted days) were the most abundant species in summer. Qualitative analysis based on features such as aromatic ring equivalence number(Xc), O/C, and H/C values for the identification and characterization of monocyclic and polycyclic aromatic compounds showed that CHON compounds were mainly aromatic compounds in winter and summer in urban Shanghai. The number and abundance of CHON compounds detected on PM2.5 polluted days were 2 and 1.5 times higher(winter) and 2.5 and 2 times higher(summer) than that on clean days, respectively. Comparing the analysis results of clean and polluted days in winter and summer, it was found that 80% of the CHON compounds with a relative abundance in the top 10 had O/N ≥ 3 and RDBE values between 5 and 8. The results suggest that these highly abundant CHON analogs may have had mononitro- or dinitro-substituted benzene rings. Correlation analysis between gaseous precursors and NACs indicated that oxidative reactive formation of VOCs(benzene, toluene, etc.) from anthropogenic emissions was the main source of NACs in summer. By contrast, it was influenced by a combination of biomass combustion emissions and secondary formation of oxidative NOx from anthropogenic VOCs in winter.

Fluorescence Quenching and the Chamber of Nitroaromatics: A Dinaphthoylated Oxacalix[4]arene's (DNOC) Adventure Captured through Computational and Experimental Study.

This research presents the application of Dinaphthoylated Oxacalix[4]arene (DNOC) as a novel fluorescent receptor for the purpose of selectively detecting nitroaromatic compounds (NACs). The characterization of DNOC was conducted through the utilization of spectroscopic methods, including 1H-NMR, 13C-NMR, and ESI-MS. The receptor demonstrated significant selectivity in acetonitrile towards several nitroaromatic analytes, such as MNA, 2,4-DNT, 2,3-DNT, 1,3-DNB, 2,6-DNT, and 4-NT. This selectivity was validated by the measurement of emission spectra. The present study focuses on the examination of binding constants, employing Stern-Volmer analysis, as well as the determination of the lowest detection limit (3σ/Slope) and fluorescence quenching. These investigations aim to provide insights into the inclusion behavior of DNOC with each of the six analytes under fluorescence spectra investigation. Furthermore, the selectivity trend of the ligand DNOC for NAC detection is elucidated using Density Functional Theory (DFT) calculations conducted using the Gaussian 09 software. The examination of energy gaps existing between molecular orbitals, namely the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), provides a valuable understanding of electron-transfer processes and electronic interactions. Smaller energy gaps are indicative of heightened selectivity resulting from favorable electron-transfer processes, whereas bigger gaps suggest less selectivity attributable to weaker electronic contacts. This work integrates experimental and computational methodologies to provide a full understanding of the selective binding behavior of DNOC. As a result, DNOC emerges as a viable chemical sensor for detecting nitroaromatic explosives.

Investigating the Potential of Fusarium solani and Phanerochaete chrysosporium in the Removal of 2,4,6-TNT.

Past and recent applications of 2,4,6-trinitrotoluene (TNT) in military and civilian industries have led to contamination of soil and marine ecosystems. Among various TNT remediation techniques, biological remediation is widely accepted for its sustainability, low cost, and scalable applications. This study was designed to isolate a fungus strain from a TNT-contaminated soil to investigate its tolerance to and potential for removal of TNT. Thus, a soil column with a history of periodic TNT amendment was used to isolate dominant strains of fungi Fusarium solani isolate, which is not commonly reported for TNT mineralization and was found predominant in the subsurface layer of the TNT-amended soil. F. solani was investigated for TNT concentration tolerance at 30, 70, and 100 mg/L on agar plates and for TNT removal in liquid cultures at the same given concentrations. F. solani activity was compared with that of a reference soil-born fungus that has been intensively studied for TNT removal (Phanerochaete chrysosporium) obtained from the American Type Culture Collection. On agar media, F. solani showed a larger colony diameter than P. chrysosporium at similar TNT concentrations, indicating its high potential to tolerate toxic levels of TNT as found in contaminated sites. In the liquid culture medium, F. solani was able to significantly produce higher biomass than P. chrysosporium in all TNT concentrations. The TNT removal percentage from the liquid culture at the highest TNT concentration of 100 mg/L reached about 85% with F. solani, while P. chrysosporium was no better than 25% at the end of an 84-h incubation period. Results indicate a significant potential of using F. solani in the bioremediation of polluted TNT soils that overcome the high concentration barrier in the field. However, further investigation is needed to identify enzymatic potential and the most effective applications and possible limitations of this method on a large scale.