Characterization of a Soft Ionization by Chemical Reaction in Transfer Ion Source Hyphenated With Supercritical Fluid Chromatography-Tandem Mass Spectrometry.

A commercially available dielectric barrier discharge ionization (DBDI) source was tested with supercritical fluid chromatography-mass spectrometry (SFC-MS). The compound mixture investigated comprised caffeine, theobromine, theophylline, uracil, testosterone, and pyrene, diluted in methanol. Dynamic response ranges were evaluated with multiple injections at different concentrations. Precision studies demonstrated the robustness and sensitivity of the ionization source across a concentration range of 10-1000 ng/mL. Results from this experiment showed linear regression of 0.99 or greater for all analytes tested over the range with a relative standard deviation (RSD) of less than 10% down to 10 ng/mL for all analytes except theobromine, which had an RSD of less than 10% down to 25 ng/mL. Notably, this study marks the first investigation of sensitivity for coupling a commercial DBDI source with SFC; a limit of detection less than 1 ng/mL was achieved for all compounds. This study demonstrates chromatographic separation by SFC and MS analysis for compounds that ionize poorly using traditional atmospheric pressure ionization, such as polycyclic aromatic hydrocarbons. Combining SFC with the DBDI source opens promising avenues for analyzing compounds that were previously challenging to characterize with standard atmospheric pressure ionization techniques.

Robust Luminescent Pyrene-Based Metal-Organic Framework Hydrogel as a pH-Responsive Fluorescence Emitter for Sensitive Immunoassay of Cardiac Troponin I.

Despite many luminescent advantages including outstanding absorption coefficient and high quantum yield, pyrene and its derivatives have been suffering from a dramatic aggregation-caused quenching (ACQ) effect. Although the dramatic ACQ effect of pyrene-based fluorophores has been restrained in pyrene-doped metal-organic frameworks (MOFs), the low loading of fluorescent (FL) units substantially impedes the improved luminescent behaviors. Herein, pyrene-based MOFs hydrogel was synthesized with a high loading of pyrene as the unique organic linker blocks instead of a dopant in MOFs. The gel matrix contributed to rigidifying the location of the FL emitters and achieving intensive FL emission and high luminescent stability and therefore efficiently overcoming the ACQ effect. Furthermore, the protonation of pyrene in the MOFs hydrogel remarkably decreased the luminescent intensity, which endowed the FL hydrogel with highly pH-responsive activity in the broad range (pH 4-10). Interestingly, glucose oxidase was immobilized into ZIF-8 as a highly efficient luminescent quencher, which contributed to catalyzing the form of gluconic acid and thus drastically quenching the FL signal of the MOFs hydrogel. Furthermore, the emitter-quencher pair of pyrene-based MOFs hydrogel and glucose oxidase was successfully employed to develop an ultrasensitive FL immunoassay platform for cardiac troponin I (as a model analyte). The limit of detection for cardiac troponin I was 5.2 pg/mL (3σ). The proof-of-principle study demonstrated the thrilling auxiliary effect of tailorable MOFs hydrogel on boosting the feasibility of aqueous insoluble FL chromophores for trace analysis.

7-Deaza-2'-deoxyisoguanosine, a Noncanonical Nucleoside for Nucleic Acid Code Expansion and New DNA Constructs: Nucleobase Functionalization of Inverse Watson-Crick and Purine-Purine Base Pairs.

7-Deaza-2'-deoxyisoguanosine forms stable inverse Watson-Crick base pairs with 5-methyl-2'-deoxyisocytidine and purine-purine base pairs with 2'-deoxyguanosine or 5-aza-7-deaza-2'-deoxyguanosine. Both base pairs expand the genetic coding system. The manuscript reports on the functionalization of these base pairs with halogen atoms and clickable side chains introduced at 7-position of the 7-deazapurine base. Oligonucleotides containing the functionalized base pairs were prepared by solid-phase synthesis. To this end, a series of phosphoramidites were synthesized and clickable side chains with short and long linkers were incorporated in oligonucleotides. Fluorescent pyrene conjugates were obtained by postmodification. Functionalization of DNA with a single inverse Watson-Crick base pair by halogens or clickable residues has only a minor impact on duplex stability. Pyrene click adducts increase (long linker) or decrease (short linker) the double helix stability. Stable hybrid duplexes were constructed containing three consecutive purine-purine pairs of 7-functionalized 7-deaza-2'-deoxyisoguanine with guanine or 5-aza-7-deazaguanine in the center and Watson-Crick pairs at both ends. The incorporation of a hybrid base pair tract of 7-deaza-2'-deoxyisoguanosine/5-aza-7-deaza-2'-deoxyguanosine pairs stabilizes the double helix strongly. Fluorescence intensity of pyrene short linker adducts increased when the 7-deazapurine base was positioned opposite to 5-methylisocytosine (inverse base pair) compared to purine-purine base pairs with guanine or 5-aza-7-deazaguanine in opposite positions. For long liker adducts, the situation is more complex. Circular dichroism (CD) spectra of purine DNA differ to those of Watson-Crick double helices and are indicative for the new DNA constructs. The impact of 7-deaza-2'-deoxyisoguanine base pair functionalization is studied for the first time and all experimental details are reported to prepare DNA functionalized at the 7-deazaisoguanine site. The influence of single and multiple incorporations on DNA structure and stability is shown. Clickable residues introduced at the 7-position of the 7-deazaisoguanine base provide handles for Huisgen-Sharpless-Meldal click cycloadditions without harming the stability of purine-pyrimidine and purine-purine base pairs. Other chemistries might be used for bioconjugation. Our investigation paves the way for the functionalization of a new DNA related recognition system expanding the common Watson-Crick regime.

The application of PAHs-Degrading Pseudomonas aeruginosa to mitigate the phytotoxic impact of pyrene on barley (Hordeum vulgare L.) and broad bean (Vicia faba L.) plants.

Mitigating the negative impacts of polycyclic aromatic hydrocarbons (PAHs) is an urgent need due to their toxicity and persistence in the environment. This study investigated the use of Pseudomonas aeruginosa ASU-B6 to detoxify pyrene (PY). The bacterium P. aeruginosa ASU-B6 is capable of degrading PY by 92% as a sole carbon source after 15 days of incubation with phthalate being the major metabolic product. In this regard, the impact of pyrene (PY), P. aeruginosa ASU-B6 (ASU-B6), the bacterial strain combined with pyrene (ASU-B6/PY) and the metabolites produced after pyrene degradation (PY-metabolites) on the germination and physiological attributes of Hordeum vulgare and Vicia faba seedlings were studied. A single application of PY or ASU-B6 showed a toxic effect on the germination of both tested seeds. Interestingly, broad bean seedlings exhibited less sensitivity to PY stress in terms of growth and metabolism compared to barley. Notably, ASU-B6 inhibited fresh and dry weight of shoots and roots of barley and, to a lesser extent, reduced the germination of broad beans compared to the control. However, the combined PY-metabolites and ASU-B6/PY showed a mutual ameliorative effect on seedlings growth, alleviating the phytotoxic impact of each component. Pyrene reduced the virulence of ASU-B6 by inhibiting the production of pyocyanin pigment, while bacteria ameliorated pyrene toxicity through its degradation. Heatmap and principal component analyses highlighted that increasing the contents of hydrogen peroxide, superoxide anion, hydroxyl radical, and lipid peroxidation positively correlated to the toxicity of PY or ASU-B6. However, improving the antioxidant system which buffers the oxidative stress induced by different combinations of PY and ASU-B6 enhanced the growth of germinated seedlings corresponding to PY or ASU-B6. This study reflected the role of ASU-B6 in ameliorating PY-phytotoxicity. In addition, the application of ASU-B6 strain is recommended as a prospective candidate for remediation of PAHs-contaminated environment with a positive impact on the plant growth and metabolic products.

Deciphering the molecular interaction of extracellular polymeric substances of a marine bacterium Pseudomonas furukawaii PPS-19 with petroleum hydrocarbons and development of bioadsorbent.

Petroleum hydrocarbon contamination is a serious hazard to marine environments, affecting ecosystems and marine life. However, extracellular polymeric substances (EPS) of marine bacteria constituting various hydrophilic and hydrophobic functional groups sequester petroleum hydrocarbons (PHs). In this study, interaction of EPS of Pseudomonas furukawaii PPS-19 with PHs such as crude oil, n-dodecane, and pyrene and its impact on PHs adsorption was investigated. Protein component of EPS was increased after treatment with PHs. Red shift of UV-Vis spectra implied change in molecular structure of EPS. Functional groups of proteins (CO, NH2) and polysaccharides (C-C, C-OH, C-O-C) predominantly interacted with PHs. Interaction with PHs affected secondary structure of EPS. Change in binding energies of corresponding functionalities of C 1s, O 1s, and N 1s confirmed the interaction. Disruption of crystalline peaks led to increased pore size in EPS primarily due to the increase in surface electronegativity. Static quenching mechanism unveils formation of complex between fulvic acid of EPS and PHs. Relative expression of alg8 gene was significantly increased in the presence of n-dodecane (6.31 fold) (P < 0.05; One way ANOVA). n-dodecane and pyrene adsorption capacity of Immobilized EPS was significantly higher (356.5 and 338.2 mg g-1, respectively) (P < 0.001; One way ANOVA) than control. Adsorption rate fits into the pseudo-second-order kinetic model. This study establishes that interaction of PHs causes structural and physical changes in EPS and EPS could be used as an adsorbent material for the sequestration of PHs pollution.

Taxis-enhanced mineralization and co-metabolism of PAHs by bacteria in micrometer-scale environments.

Polycyclic aromatic hydrocarbons (PAHs) are associated with micropores in sediments and soils. This limits the bioaccessibility of these compounds via existing bioremediation technologies, as biodegradation is strongly influenced by the ability of bacteria to access different sizes of pores. In this work, we employed naphthalene and pyrene as model contaminants to evaluate the transformation capacity of the soil bacterium Pseudomonas putida G7 (2 × 1 µm) via mineralization and co-metabolic activity, respectively. Under non-growing conditions and in the absence of hydraulic flow, we examined how the tactic behavior of this motile bacterium influenced biodegradation of these two PAHs when passing through membranes with micrometer-sized pores (3 and 5 µm). The bacteria were spontaneously retained by the membranes, which blocked the contaminants away from a passive dosing source. However, the cells were mobilized through 5 µm pores after the application plant root exudate components (γ-aminobutyric acid, citrate and fructose) as strong chemoeffectors, which enhanced the mineralization of naphthalene and co-metabolism of pyrene. The tactic-mediated biodegradation enhancement did not occur through 3 µm pores, possibly due a physical constrain to the gradient sensing mechanism. Our results suggest that bacterial transport by chemotaxis may enhance the biotransformation of poorly bioaccessible contaminants present in micro-meter scale environments.

Migration of fluoranthene, phenanthrene, and pyrene in soil environment during the growth of Brassica rapa subsp. chinensis.

The escalating concern surrounding fluoranthene (FLN), phenanthrene (Phe), and pyrene (Pyr), underscores the urgency to investigate their dynamics in the context of agricultural ecosystems. Brassica rapa subsp. chinensis (Bok choy), a globally consumed vegetable, holds particular significance in this scenario. This study explores the migration and transformation of FLN, Phe, and Pyr from soil to Brassica rapa subsp. chinensis during its growth. The germination rates of seeds in these treatments varied, with soil+Bok choy and soil+FLN+Bok choy treatments showing higher rates (77.8 %), while soil+mix+Bok choy exhibited the lowest rate (11.1 %) after 3 days. Analyzing the distribution of FLN, Phe, and Pyr in Brassica rapa subsp. chinensis parts after 30 days revealed a sequence of accumulation in stem> root> leaf. This study provides information on practical implications for regulating the soil-plant migration and transformation of FLN, Phe, and Pyr, offering valuable insights for migration of PAHs pollution in agricultural settings.

Interaction between polycyclic aromatic hydrocarbons and thymine (T)-base induces double-strand DNA distortion in different species.

Polycyclic aromatic hydrocarbons (PAHs) are potent inhibitors of DNA that can induce genetic damage, abnormal gene expression, and metabolic disorders upon interfacing with biological macromolecules. However, the mechanism of their interactions with DNA remains elusive. Therefore, this study selected three representative PAHs, including phenanthrene (Phen), pyrene (Pyre), and benzo[a]pyrene (B[a]P), and explored their binding mechanisms with the double-strand DNA (dsDNA) from different species, including 1J1V (Escherichia coli), 6J5B (Arabidopsis thaliana), and 6Q1V (Homo sapiens). The results revealed that binding between PAHs and dsDNA occurred in the groove via van der Waals forces and π-π stacking, with the carboxyl oxygen atom of the thymine (T)-base within dsDNA being the key binding site. This result was further confirmed by the spectroscopic experiments, where significant changes in the peak of the T-base were observed after PAHs-dsDNA binding. More interestingly, the total binding energies of Pyre with the three dsDNA were -138.800 kJ/mol (Pyre-1J1V), -105.523 kJ/mol (Pyre-6J5B), and -127.567 kJ/mol (Pyre-6Q1V), respectively, all of which were higher than those of Phen and B[a]P. This suggests that that Pyre has the strongest dsDNA binding ability. Additionally, analysis of the thermodynamic parameters indicated that the interactions between the three PAHs and dsDNA were exothermic reactions. In contrast, the Pyre-dsDNA interaction predominantly involved van der Waals forces and hydrogen bonding due to the enthalpy change (∆H) < 0 and entropy change (∆S) < 0, while the Phen-dsDNA and B[a]P-dsDNA interactions predominantly involved hydrophobic forces due to ∆H > 0 and ∆S > 0. Furthermore, Pyre caused local distortion of dsDNA, which was more pronounced under atomic force microscopy (AFM). In summary, this study has unveiled a new phenomenon of binding between PAHs and dsDNA. This sheds light on the carcinogenic potential and environmental impacts of PAHs pollution.

Exposure-associated DNA methylation among people exposed to multiple industrial pollutants.

BACKGROUND: Current research on the epigenetic repercussions of exposure to a combination of pollutants is limited. This study aims to discern DNA methylation probes associated with exposure to multiple pollutants, serving as early effect markers, and single-nucleotide polymorphisms (SNPs) as surrogate indicators for population susceptibility. The investigation involved the analysis of urine exposure biomarkers for 11 heavy metals (vanadium, arsenic, mercury, cadmium, chromium, nickel, lead, manganese, copper, strontium, thallium), polycyclic aromatic hydrocarbon (PAHs) (1-hydroxypyrene), genome-wide DNA methylation sequencing, and SNPs array on all study participants. The data were integrated with metabolomics information and analyzed both at a community level based on proximity to home addresses relative to the complex and at an individual level based on exposure biomarker concentrations. RESULTS: On a community level, 67 exposure-related CpG probes were identified, while 70 CpG probes were associated with urine arsenic concentration, 2 with mercury, and 46 with vanadium on an individual level. These probes were annotated to genes implicated in cancers and chronic kidney disease. Weighted quantile sum regression analysis revealed that vanadium, mercury, and 1-hydroxypyrene contributed the most to cg08238319 hypomethylation. cg08238319 is annotated to the aryl hydrocarbon receptor repressor (AHRR) gene, and AHRR hypomethylation was correlated with an elevated risk of lung cancer. AHRR was further linked to deregulations in phenylalanine metabolism, alanine, aspartate, and glutamate metabolism, along with heightened oxidative stress. Additionally, three SNPs (rs11085020, rs199442, and rs10947050) corresponding to exposure-related CpG probes exhibited significant interaction effects with multiple heavy metals and PAHs exposure, and have been implicated in cancer progression and respiratory diseases. CONCLUSION: Our findings underscore the pivotal role of AHRR methylation in gene-environment interactions and highlight SNPs that could potentially serve as indicators of population susceptibility in regions exposed to multiple heavy metals and PAHs.

Fluorogenic Monitoring of α-Amylase in Human Urine for Straightforward Diagnosis of Pancreatic Diseases.

In this study, we developed a sensitive method for monitoring α-amylase using a fluorogenic approach based on the host-guest complexation between an amphiphilic pyrenyl derivative (1) and γ-cyclodextrins (γ-CDs). The compound 1 self-assembles into nanofibrils in aqueous solutions. Upon the introduction of γ-CD, compound 1 forms an inclusion complex with it. This complex then participates in the formation of a 2 : 2 complex with another complex, leading to strong excimer fluorescence. Upon interaction with α-amylase, γ-CD undergoes hydrolysis, leading to the regeneration of nanofibrils, which is accompanied by a decrease in excimer fluorescence and an increase in monomeric fluorescence. This ratiometric fluorescence color change enables the sensitive detection of low levels of α-amylase in human urine, offering a practical approach for early screening of pancreatic-related diseases.

Development of a non-separative screening strategy based on mass spectrometry for the semi-quantification of urinary polycyclic aromatic hydrocarbon metabolites.

A fast and non-separative screening strategy is presented for the analysis of five urinary metabolites of polycyclic aromatic hydrocarbons (PAHs), namely 2-naphthol, 1-acenaphthenol, 2-hydroxyfluorene, 9-phenanthrol and 1-hydroxypyrene. These hydroxylated derivatives (OH-PAHs) were subjected to enzymatic hydrolysis and were extracted from urine using a liquid-liquid extraction (LLE). The profile signals were obtained by direct injection of the sample into a programmed temperature vaporizer coupled to a quadrupole mass spectrometer via a deactivated fused silica tubing (PTV-qMS). Semi-quantitative determination was carried out by means of partial least squares regression (PLS1) using urine samples free of the analytes and spiked at several uncorrelated concentration levels. The multivariate calibration models worked satisfactorily, with errors ranging between 30 and 33 % for all the analytes except for 1-acenaphthenol that provided an error of 39 % when external validation set was considered. The repeatability and reproducibility, expressed as relative standard deviation (RSD), were ranged between 8-16 % and 11-18 %, respectively. The proposed method could be a useful tool for semi-quantification purposes of five OH-PAHs in urine samples, identifying positive samples for subsequent further chromatographic separation (confirmation), thus saving time and costs.

A comparative account of phototoxicity of anthracene and pyrene in the tadpoles of the anuran amphibian Fejervarya limnocharis using multiple toxicological end points.

Anthracene (Anth) and pyrene (Pyr), two of the priority polycyclic aromatic hydrocarbons (PAHs), being lipophilic in nature, not only accumulate in animals, but also settle in the sediment of water bodies leading to continuous exposure for animals. Anth and Pyr when exposed to sunlight can be photoactivated and have harmful effects on aquatic organisms. A comparative analysis was carried out to assess the acute, sub-chronic, genetic and biochemical toxicity of Anth and Pyr in F. limnocharis tadpoles following short exposures to sunlight on a daily basis. In the bioaccumulation studies, it was found that both Anth and Pyr accumulated in the tadpole tissues in a concentration and time dependent manner. The LC50 values for Anth (under 15 min of daily sunlight exposure) were found to be 2.87, 2.59, 2.28, 1.80 mg/L at 24, 48, 72 and 96 h of the exposures. The corresponding LC50 values for Pyr were 1.03, 0.80, 0.62, 0.42 mg/L. Sublethal exposure of Anth and Pyr affected the survivality, time to metamorphosis as well as morphometric parameters under sunlight exposure. In the genotoxicity assessment studies, particularly the micronucleus test and comet assay, it was found that Pyr led to a higher incidence of micronucleus formation and DNA damage in comparison to Anth. The exposure to PAHs resulted in significant changes in the activity of antioxidant-mediated protective response, specifically the SOD activity, which varied between the groups treated with Anth and Pyr. On the other hand, Pyr treated group showed a higher level of GSH as compared to Anth treated groups. Moreover, the elevation in MDA level in the Anth and Pyr treated groups suggests an increase in lipid peroxidation. Future research should focus on understanding the ecotoxicological risk faced by anuran amphibia due to PAHs that frequently occur in aquatic environments and developing strategies to mitigate these risks.

Cadmium and pyrene in the soil modify the properties of earthworm-mediated soil.

Earthworms are pivotal in soil ecosystems due to their crucial role in shaping soil characteristics through casts and burrow walls. Previous research has predominantly focused on the direct impact of soil pollution on live earthworms, overlooking the subsequent effects on earthworm-mediated soil, such as casts and burrow walls. Using 2D-terraria as incubation containers and the geophagous earthworm species Metaphire guillelmi, this study assessed the change in various properties of earthworm-mediated soil in both uncontaminated soils and Cd- and Pye-contaminated soils. Overall, both Cd and Pye overall improved the ammonium nitrogen (NH4+-N), Olsen's phosphorus (Olsen-P) levels, and invertase and catalase activities while decreasing catalase activities in earthworm-mediated soil. They also fluctuating affected the pH, soil organic matter (SOM) content, soil urease, alkaline phosphatase activities, and microbial functional genes in the cast and burrow walls. These results indicated that earthworms remained crucial "ecosystem engineers" even in polluted soil. Additionally, differences were observed in the responses of properties between casts and burrow walls, showing unequal contributions of transit-through-gut and burrowing processes to soil modification. Specifically, transit-through-gut was found to have a more significant influence on soil NH4+-N and Olsen-P content compared to burrowing behavior. Regarding the pattern of microbial functional genes in earthworm-associated compartments, results revealed that they differed significantly in casts from those in bulk soil and burrow walls under unpolluted conditions, with pollution-enhancing disparities among compartments. Furthermore, NH4+-N and Olsen-P content, urease, and catalase activities in burrow walls and/or casts were identified as potential biomarkers for soil pollution, exhibiting a clear dose-effect relationship. Developing such biomarkers could address ethical concerns related to conventional earthworm biomarkers that require sacrificing earthworms. This study provides insights into the consequences of soil pollution on earthworm-mediated soil components, highlighting the importance of considering the indirect effects of contaminants on soil ecosystems.

Effects of N, N-bis (carboxymethyl)-L-glutamic acid and polyaspartic acid on the phytoremediation of cadmium in contaminated soil at the presence of pyrene: Biochemical properties and transcriptome analysis.

Chelator-assisted phytoremediation is an efficacious method for promoting the removal efficiency of heavy metals (HMs). The effects of N, N-bis(carboxymethyl)-L-glutamic acid (GLDA) and polyaspartic acid (PASP) on Cd uptake and pyrene removal by Solanum nigrum L. (S. nigrum) were compared in this study. Using GLDA or PASP, the removal efficiency of pyrene was over 98%. And PASP observably raised the accumulation and transport of Cd by S. nigrum compared with GLDA. Meanwhile, both GLDA and PASP markedly increased soil dehydrogenase activities (DHA) and microbial activities. DHA and microbial activities in the PASP treatment group were 1.05 and 1.06 folds of those in the GLDA treatment group, respectively. Transcriptome analysis revealed that 1206 and 1684 differentially expressed genes (DEGs) were recognized in the GLDA treatment group and PASP treatment group, respectively. Most of the DEGs found in the PASP treatment group were involved in the metabolism of carbohydrates, the biosynthesis of brassinosteroid and flavonoid, and they were up-regulated. The DEGs related to Cd transport were screened, and ABCG3, ABCC4, ABCG9 and Nramp5 were found to be relevant with the reduction of Cd stress in S. nigrum by PASP. Furthermore, with PASP treated, transcription factors (TFs) related to HMs such as WRKY, bHLH, AP2/ERF, MYB were down-regulated, while more MYB and bZIP TFs were up-regulated. These TFs associated with plant stress resistance would work together to induce oxidative stress. The above results indicated that PASP was more conducive for phytoremediation of Cd-pyrene co-contaminated soil than GLDA.

Structural and Mechanical Characterization of DNA-Tethered Membranes on Graphene.

Lipid membranes that are separated from the surface of graphene by DNA tethers were prepared by surface functionalization with pyrene coupled to single-stranded DNA (ssDNA), followed by self-assembly of the mixture of ssDNA-functionalized phospholipid and the matrix phospholipids. The formation of uniform membranes was confirmed by fluorescence microscopy, and the structures of the systems before and after hybridization in the direction perpendicular to the global plane of the membranes were investigated using high-energy X-ray reflectivity. The thickness values of the DNA spacers (15 and 37 bp) calculated from the best-fit results were less than the expected thicknesses of the double-stranded DNA (dsDNA) chains taking the upright conformation, indicating that the DNA spacers are tilted with respect to the direction normal to the surface. The Young's moduli of the DNA-tethered membranes obtained by AFM nanoindentation showed higher values than the membranes with no DNA tethers, which suggests that the DNA layer resists against the compression, lifting up the membrane. Intriguingly, the presence of DNA tethers caused no increase in the yield depth. The smaller thickness values as well as the unchanged yield depth suggest that the dsDNA chains can tilt and rotate, which can be attributed to the flexible pyrene-DNA junction.

Pyrenetetrasulfonate-grafted 2D ultrathin metal-organic layer as new electrochemiluminescence emitters for ultrasensitive microRNA-21 assay.

The exploration of novel electrochemiluminescence (ECL) luminophores with excellent ECL properties is a current research hotspot in the ECL field. Herein, a novel high-efficiency Ru-complex-free ECL emitter PyTS-Zr-BTB-MOL has been prepared by using porous ultrathin Zr-BTB metal-organic layer (MOL) as carrier to coordinatively graft the cheap and easily available polycyclic aromatic hydrocarbon (PAH) derivative luminophore PyTS whose ECL performance has never been investigated. Gratifyingly, the ECL intensity and efficiency of PyTS-Zr-BTB-MOL were markedly enhanced compared to both PyTS monomers and PyTS aggregates. The main reason was that the distance between pyrene rings was greatly expanded after the PyTS grafting on the Zr6 clusters of Zr-BTB-MOL, which overcame the aggregation-caused quenching (ACQ) effect of PyTS and thus enhanced the ECL emission. Meanwhile, the porous nanosheet structure of PyTS-Zr-BTB-MOL could distinctly increase the exposure of PyTS luminophores and shorten the diffusion paths of coreactants and electrons/ions, which effectively promoted the electrochemical excitation of more PyTS luminophores and thus achieved a further ECL enhancement. In light of the remarkable ECL property of PyTS-Zr-BTB-MOL, it was employed as an ECL indicator to build a novel high-sensitivity ECL biosensor for microRNA-21 determination, possessing a satisfactory response range (100 aM to 100 pM) and an ultralow detection limit (10.4 aM). Overall, this work demonstrated that using MOLs to coordinatively graft the PAH derivative luminophores to eliminate the ACQ effect and increase the utilization rate of the luminophores is a promising and efficient strategy to develop high-performance Ru-complex-free ECL materials for assembling ultrasensitive ECL biosensing platforms.

Systemic oxidative stress levels during the course of pregnancy: Associations with exposure to air pollutants.

Increased systemic oxidative stress, implicated in adverse pregnancy outcomes for both mothers and fetuses, has been associated with gestational exposure to air pollutants such as polycyclic aromatic hydrocarbons (PAHs), fine particulate matter (PM2.5), and nitrogen dioxide (NO2). However, it is unclear whether exposure to pollutants at levels below the current air quality standards can increase oxidative stress in pregnant women. In a cohort of 305 pregnant persons residing in western New York, we examined the association between exposure to PM2.5, NO2, and PAHs (measured as urinary 1-hydroxypyrene) and urinary biomarkers of oxidative stress (malondialdehyde [MDA] and 8-hydroxy-2'-deoxyguanosine [8-OHdG]) measured in each trimester. After controlling for gestational stage, maternal age, lifestyles, and socioeconomic factors, each interquartile range (IQR) increase in 1-hydroxypyrene concentration (65.8 pg/ml) was associated with a 7.73% (95%CI: 3.18%,12.3%) higher in MDA levels throughout the pregnancy and in the first and second trimester. An IQR increase in PM2.5 concentration (3.20 µg/m3) was associated with increased MDA levels in the first trimester (8.19%, 95%CI: 0.28%,16.1%), but not the 2nd (-7.99%, 95% CI: 13.8%, -2.23%) or 3rd trimester (-2.81%, 95% CI: 10.0%, 4.38%). The average cumulative PM2.5 exposures in the 3-7 days before urine collection were associated with increased 8-OHdG levels during the second trimester, with the largest difference (22.6%; 95% CI: 3.46%, 41.7%) observed in relation to a one IQR increase in PM2.5 concentration in the previous 7 days. In contrast, neither oxidative stress biomarker was associated with NO2 exposure. Observed in pregnant women exposed to low-level air pollution, these findings expanded previously reported associations between systemic oxidative stress and high-level PM2.5 and PAH concentrations. Further, the first and second trimesters may be a susceptible window during pregnancy for oxidative stress responses to air pollution exposure.

Evaluating the Kinetics and Molecular Mechanism for Biomimetic Metabolic Activation of PAHs by Surface-Enhanced Raman Scattering Spectroscopy.

Biomimetic cytochrome P450 for chemical activation of environmental carcinogens is an efficient in vitro model for evaluating their mutagenicity and ultimately acquiring the metabolites that cannot be easily accessed by conventional routes of organic synthesis. Different kinds of mutagen derived from polyaromatic hydrocarbons (PAHs) by metalloporphyrin/oxidant model systems have been reported, but the underlying molecular mechanisms are poorly understood. Herein, we have for the first time demonstrated an effective surface-enhanced Raman scattering (SERS) protocol to study the dynamics and biomimetic metabolic behaviors of pyrene (Pyr) in the presence of various oxygen donors. Quantitative information on the relative concentration of Pyr and its metabolites in the biomimetic system can be extracted from the SERS spectra. On the basis of our results, we conclude that the oxidative metabolism of Pyr is highly influenced by the types and concentrations of oxygen donors, leading to the formation of 1-hydroxypyrene and dioxygenated products. Besides, the addition of an appropriate amount of an organic solvent can promote the formation of secondary oxidation products. These results offer valuable insights into the dynamics of PAHs metabolism and the regulation of their metabolic pathways in biomimetic activation. In comparison to traditional liquid chromatography-mass spectrometry, the present SERS approach is more suitable for high-throughput evaluation of the metabolic process and kinetics of PAHs. We anticipate that this approach will enable a more general and comprehensive tracking of metabolic dynamics and molecular mechanisms involved in the biomimetic activation of other xenobiotics, such as procarcinogens, promutagens, and drugs.

Sphaeropsidin A C15-C16 Cross-Metathesis Analogues with Potent Anticancer Activity.

We recently discovered that sphaeropsidin A (SphA), a fungal metabolite from Diplodia cupressi, overcomes apoptosis resistance in cancer cells by inducing cellular shrinkage by impairing regulatory volume increase. Previously, we prepared a pyrene-conjugated derivative of SphA by a cross-metathesis reaction involving the phytotoxin's C15,C16-alkene. This derivative's evaluation in a cancer cell panel revealed a significant increase in potency, with the IC50 values 5-10× lower than those displayed by the original natural product. Herein, we describe the preparation and anticancer evaluation of fifteen novel C15,C16-alkene cross-metathesis analogues in which the pyrene moiety was replaced with other aromatic or non-aromatic hydrophobic groups. The idea for this replacement was to prepare a family of compounds that would not be predicted to be mutagenic compared with the original pyrene analogue. We predict several of our new compounds to be non-mutagenic, while retaining the high potency of the original pyrene-containing analogues. Examples of these potential lead compounds included those containing pentamethylphenyl and triphenylethylene pendant groups. As an additional feature of the current investigation, we prepared several deuterated pyrene-containing compounds to overcome intellectual property issues associated with non-patentability of the original pyrene derivative.

Polyaromatic Hydrocarbon-Functionalized 2D MXene-Based 3D Porous Antifouling Nanocomposite with Long Shelf Life for High-Performance Electrochemical Immunosensor Applications.

Affinity-based electrochemical (AEC) biosensors have gained more attention in the field of point-of-care management. However, AEC sensing is hampered by biofouling of the electrode surface and degradation of the antifouling material. Therefore, a breakthrough in antifouling nanomaterials is crucial for the fabrication of reliable AEC biosensors. Herein, for the first time, we propose 1-pyrenebutyric acid-functionalized MXene to develop an antifouling nanocomposite to resist biofouling in the immunosensors. The nanocomposite consisted of a 3D porous network of bovine serum albumin cross-linked with glutaraldehyde with functionalized MXene as conductive nanofillers, where the inherited oxidation resistance property of functionalized MXene improved the electrochemical lifetime of the nanocomposite. On the other hand, the size-extruded porous structure of the nanocomposite inhibited the biofouling activity on the electrode surface for up to 90 days in real samples. As a proof of concept, the antifouling nanocomposite was utilized to fabricate a multiplexed immunosensor for the detection of C-reactive protein (CRP) and ferritin biomarkers. The fabricated sensor showed good selectivity over time and an excellent limit of detection for CRP and ferritin of 6.2 and 4.2 pg/mL, respectively. This research successfully demonstrated that functionalized MXene-based antifouling nanocomposites have great potential to develop high-performance and low-cost immunosensors.