Electronic cigarettes (E-cigs) have experienced sharp increases in popularity over the past five years due to many factors, including aggressive marketing, increased restrictions on conventional cigarettes, and a perception that E-cigs are healthy alternatives to cigarettes. Despite this perception, studies on health effects in humans are extremely limited and in vivo animal models have not been generated. Presently, we determined that E-cig vapor contains 7x1011 free radicals per puff. To determine whether E-cig exposure impacts pulmonary responses in mice, we developed an inhalation chamber for E-cig exposure. Mice that were exposed to E-cig vapor contained serum cotinine concentrations that are comparable to human E-cig users. E-cig exposure for 2 weeks produced a significant increase in oxidative stress and moderate macrophage-mediated inflammation. Since, COPD patients are susceptible to bacterial and viral infections, we tested effects of E-cigs on immune response. Mice that were exposed to E-cig vapor showed significantly impaired pulmonary bacterial clearance, compared to air-exposed mice, following an intranasal infection with Streptococcus pneumonia. This defective bacterial clearance was partially due to reduced phagocytosis by alveolar macrophages from E-cig exposed mice. In response to Influenza A virus infection, E-cig exposed mice displayed increased lung viral titers and enhanced virus-induced illness and mortality. In summary, this study reports a murine model of E-cig exposure and demonstrates that E-cig exposure elicits impaired pulmonary anti-microbial defenses. Hence, E-cig exposure as an alternative to cigarette smoking must be rigorously tested in users for their effects on immune response and susceptibility to bacterial and viral infections.
Particular matter (PM) is emitted during thermal decomposition of waste. During this process, aromatic compounds chemisorb to the surface of metal-oxide-containing PM, forming a surface-stabilized environmentally persistent free radical (EPFR). We hypothesized that EPFR-containing PM redox cycle to produce ROS and that this redox cycle is maintained in biological environments. To test our hypothesis, we incubated model EPFRs with the fluorescent probe dihydrorhodamine (DHR). Marked increases in DHR fluorescence were observed. Using a more specific assay, hydroxyl radicals (•OH) were also detected, and their level was further increased by co-treatment with thiols or ascorbic acid (AA), known components of epithelial lining fluid. Next, we incubated our model EPFR in bronchoalveolar lavage fluid (BALF) or serum. Detection of EPFRs and •OH verified that PM generate ROS in biological fluids. Moreover, incubation of pulmonary epithelial cells with EPFR-containing PM increased •OH levels compared to PM lacking EPFRs. Finally, measurements of oxidant injury in neonatal rats exposed to EPFRs by inhalation suggested that EPFRs induce an oxidant injury within lung lining fluid and that the lung responds by increasing antioxidant levels. In summary, our EPFR-containing PM redox cycle to produce ROS, and these ROS are maintained in biological fluids and environments. Moreover, these ROS may modulate toxic responses of PM in biological tissues such as the lung.
In this study, we report synthesis and characterization of novel carbazole-based group of uniform materials based on organic salts (GUMBOS), as well as potential applications of these compounds. These organic-based compounds exhibit high thermal stability (decomposition temperatures in the range of 395−432 °C) and photostability. In addition, these compounds have appreciably high fluorescence quantum yields (73−99%) with broad emissions in the visible region and quantum yields which depend on the GUMBOS counteranion. The physicochemical, optical, and electrochemical properties of these materials are investigated and detailed here. Evaluation of band gap values (3.4 eV), HOMO−LUMO energy levels, and measured fluorescence quantum yields as compared to carbazole suggest potential use in organic light-emitting diodes. Computational results are found to be complementary to experimental results, and calculated band gaps are in agreement with experimentally obtain values.
Development of ionic liquid (IL)-based colorimetric sensor arrays for detection and identification of chemicals in both the aqueous and vapor phases is reported. These facile and inexpensive optoelectronic sensors were fabricated by using ionic liquids (ILs) derived from readily available pH indicator dyes. A series of 12 different chemosensory ILs were synthesized by pairing anionic pH indicator dyes with trihexyl(tetradecyl)phosphonium ([P 66614 ]) cation via an ion exchange reaction. The incorporation of the [P 66614 ] cation imparted hydrophobic characteristics to these ILs, and this induced hydrophobicity led to their desired low solubility in aqueous solutions, as well as eliminated the need for a specialized hydrophobic matrix/substrate for immobilization. In this manuscript, four different matrices, i.e. glass microfiber filter papers, cotton threads, silica thin layer chromatography (TLC) plates, and alumina TLC plates, were employed for fabrication of sensor arrays. These sensor arrays were used to analyze pH values of aqueous solutions as well as for detection of acidic and basic vapors. To further prove the applicability of these IL sensor arrays as tools to sense closely related complex materials, the arrays were applied to successful discrimination of aqueous solutions of smoke from three commercially available cigarettes. The digital data generated from these sensor arrays were used in developing predictive models for accurately identifying various analytes. Two approaches were used for developing the models, and two methods were applied for assessing the predictive accuracy of the models. Use of cotton threads as a matrix led to development of a more flexible, low volume, and lightweight array to estimate pH and detect a variety of vapors. These wearable arrays may possibly be incorporated into bandages, sweatbands, diapers, and similar systems. Overall, these IL-based sensor arrays should provide a new research direction in the development of advanced colorimetric sensor arrays for detection and identification of a range of analytes relevant to many different applications.
A novel pH sensitive, colorimetric ionic liquid nanosensor based on phosphonium salts of fluorescein is reported. Herein, fluorescein salts of various stoichiometries were synthesized by use of a trihexyltetradecylphosphonium cation [TTP]+ in combination with dianionic [FL]2− and monoanionic [FL]− fluorescein. Nanomaterials derived from these two compounds yielded contrasting colorimetric responses in neutral and acidic environments. Variations in fluorescence spectra as a function of pH were also observed. Examination of TEM and DLS data revealed significant expansion in the diameter of [TTP]2[FL] nanodroplets in acidic environments of variable pHs. A similar trend was also observed for [TTP][FL] nanoparticles. The pH dependent colorimetric and other optical properties of these nanomaterials are attributed to alterations in molecular orientations and stacking as suggested by measuring the absorption, fluorescence, and zeta potential. Since the pH is an important indicator for many diseases, including cancer, these nanosensors are considered to be potential candidates for biomedical applications.
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