Application of Nanosecond Pulsed Electric Field and Autofluorescence Lifetime Microscopy of FAD in Lung Cells

Exposure of nanosecond pulsed electric fields (nsPEFs) to live cells is an increasing research interest in biology and medicine. Despite extensive studies, a question still remains as to how effects of application of nsPEF on intracellular functions are different between cancerous cells and normal cells and how the difference can be detected. Herein, we have presented an approach of autofluorescence lifetime (AFL) microscopy of flavin adenine dinucleotide (FAD) to detect effects of application of nsPEF having 50 ns of a pulse width, nsPEF(50), on intracellular function in lung cancerous cells, A549 and H661, which show nsPEF(50)-induced apoptosis, and normal cells, MRC-5, in which the field effect is less or not induced. Then, the application of nsPEF(50) is shown to increase the lifetime of FAD autofluorescence in lung cancerous cells, whereas the electric field effects on the autofluorescence of FAD was not significant in normal healthy cells, which indicates that the lifetime measurements of FAD autofluorescence are applicable to detect the field-induced change in intracellular functions. Lifetime and intensity microscopic images of FAD autofluorescence in these lung cells were also acquired after exposure to the apoptosis-inducer staurosporine (STS). Then, it was found that the AFL of FAD became longer after exposure not only in the cancerous cells but also in the normal cells. These results indicate that nsPEF(50) applied to lung cells induced apoptotic cell death only in lung cancerous cells (H661 and A549) but not in lung normal cells (MRC-5), whereas STS induced apoptotic cell death both in lung cancerous cells and in lung normal cells. The lifetime microscopy of FAD autofluorescence is suggested to be very useful as a sensitive detection method of nsPEF-induced apoptotic cell death.

Pyrene-Based AIEE Active Nanoprobe for Zn2+ and Tyrosine Detection Demonstrated by DFT, Bioimaging, and Organic Thin-Film Transistor

The development of aggregation-induced emission enhancement (AIEE) active nanoprobes without any synthetic complication for solution-state and organic thin-film transistor (OTFT)-based sensory applications is still a challenging task. In this study, the novel pyrene-incorporated Schiff base (5-phenyl-4-((pyren-1-ylmethylene)amino)-4H-1,2,4-triazole-3-thiol; PT2) with an AIEE property was synthesized via a one-pot reaction and was reported for detecting Zn²⁺ and tyrosine in the solution state and OTFT. In the AIEE studies of PT2 (in CH₃CN) at various water fractions (f_w: 0-97.5%), the existence of J-aggregation, crystalline changes, and nanofibers formation was confirmed by ultraviolet absorption/photoluminescence (UV/PL) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic-light scattering (DLS) techniques. Similarly, PT2-based Zn²⁺ detection and sensory reversibility with tyrosine were demonstrated by UV/PL studies with evidence related to crystalline/nanolevel changes in PXRD, SEM, TEM, AFM, and DLS data. Distinct decay profiles associated with the AIEE and sensory responses of PT2 were observed in time-resolved photoluminescence spectra. From the standard deviation and linear fittings of PL titrations, detection limits (LODs) of the Zn²⁺ with PT2 and the tyrosine with PT2-Zn²⁺ were estimated as 0.79 and 45 nM, respectively. High-resolution mass and ¹H NMR results confirmed 2:1 and 1:1 stoichiometry and binding sites of PT2-Zn²⁺-PT2* and tyrosine-Zn²⁺ complexes. Moreover, the values of association constants determined by linear fittings were 4.205 × 10^-7 and 1.73 × 10^-8 M^-2, correspondingly. Optimization via the density functional theory disclosed the binding sites and suppression of twisted intramolecular charge transfer/photoinduced electron transfer (TICT/PET) as well as the involvement of restricted intramolecular rotation in the AIEE and PET "ON-OFF-ON" mechanisms in the Zn²⁺ and tyrosine sensors. Results from the B16-F10 cellular and zebrafish imaging of AIEE, Zn²⁺, and tyrosine sensors further attested the applicability of PT2 in biological samples. Finally, the PT2 and pentacene-incorporated OTFT devices were fabricated. The devices displayed more than 90% change in drain-source current when reacted with Zn²⁺ with an LOD of 5.46 μM but showed no response to tyrosine, thereby confirming the reversibility. Moreover, the OTFT devices also demonstrated Zn²⁺ ion detection in tap water and lake water samples.

Novel rhodamine probe for colorimetric and fluorescent detection of Fe3+ ions in aqueous media with cellular imaging

A novel rhodamine-pyridine conjugated spectroscopic probe RhP was synthesized and its X-ray single crystalline properties were revealed with tabulation. The RhP displayed a distinct pale-pink colorimetric and "turn-on" fluorescent response to Fe³⁺ in aqueous media [H₂O:DMSO (95:5, v/v)] than that of other interfering ions. During the Fe³⁺ recognition, the absorption (UV-Vis) and photoluminescence (PL) spectral studies revealed new peaks at 561 and 592 nm, respectively. The 1:1 stoichiometry and binding sites were verified by Job's plot, ESI-mass, and ¹H NMR titrations. Subsequently, LOD and binding constant for RhP + Fe³⁺ complex were estimated as 102.3 nM and 6.265 × 10⁴ M^-1 from linear fitting and Benesi-Hildebrand plots, correspondingly. Sensor reversibility of RhP + Fe³⁺ by EDTA was demonstrated by UV/PL and TRPL investigations. Moreover, the photoinduced energy transfer mechanism and band gap changes were established from the DFT interrogations. Lastly, cellular imaging studies were carried out to authenticate the real applicability of RhP in Fe³⁺ detection.

Diversiform Nanostructures Constructed from Tetraphenylethene and Pyrene-Based Acid/Base Controllable Molecular Switching Amphiphilic [2]Rotaxanes with Tunable Aggregation-Induced Static Excimers

Dual-emissive tetraphenylethene (TPE) and pyrene-containing amphiphilic molecules are of great interest because they can be integrated to form stimuli responsive materials with various biological applications. Herein, we report the study of mechanically interlocked molecules (MIMs) with aggregation-induced static excimer emission (AISEE) property through a series of TPE and pyrene-based amphiphilic [2]rotaxanes, where t-butylcalix[4]arene with hydrophobic nature was used as the macrocycle. Evidently, by adorning TPE and pyrene units in [2]rotaxanes P1, P2, P1-b, and P2-b, they display remarkable emission bands in 70% of water fraction (f_w) in tetrahydrofuran (THF)/water mixture, which could be attributed to the restricted intramolecular rotation of phenyl groups, whereas prominent blue-shifted excimer emission of pyrene started to appear as f_w reached 80% for P1 and 90% for P1-b, P2, and P2-b, which was ascribed to the favorable π-π stacking and hydrophobic interactions of the pyrene rings that enabled their static excimer formation. The well-defined distinct amphiphilic nanostructures of [2]rotaxanes including hollowspheres, mesoporous nanostructures, spheres, and network linkages can be driven smoothly depending on the molecular structures and their aggregated states in THF/water mixture. These fascinating diversiform nanostructures were mainly controlled by the skillful manner of reversible molecular shuttling of t-butylcalix[4]arene macrocycle and also the interplay of multinoncovalent interactions. To further understand the aggregation capabilities of [2]rotaxanes, the human lung fibroblasts (MRC-5) living cell incubated with either P1, P2, P1-b, or P2-b was studied and monitored by confocal laser scanning microscopy. The AISEE property was achieved at an astonishing level by integrating TPE and pyrene to MIM-based reversible molecular switching [2]rotaxanes; furthermore, distinct nanostructures, especially hollowspheres and mesoporous nanostructures, were observed, which are rarely reported in the literature but are highly desirable for future applications.

Characterization of endogenous fluorescence in nonsmall lung cancerous cells: A comparison with nonmalignant lung normal cells

Monitoring fluorescence properties of endogenous fluorophores such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) in normal and cancerous cells provide substantial information noninvasively on biochemical and biophysical aspects of metabolic dysfunction of cancerous cells. Time-resolved spectral profiles and fluorescence lifetime images of NADH and FAD were obtained in human lung nonsmall carcinomas (H661 and A549) and normal lung cells (MRC-5). Both fluorophores show the fast and slowly decaying emission components upon pulsed excitation, and fluorescence spectra of NADH and FAD show blue- and red-shifts, respectively, during their decay. All identified lifetime components of NADH and FAD were found to be shorter in cancerous cells than in normal cells, no matter how they were measured under different extra-cellular conditions (cells suspended in cuvette and cells attached on glass substrate), indicating that the changes in metabolism likely altered the subcellular milieu and potentially also affected the interaction of NADH and FAD with enzymes to which these cofactors were bound. The intensity ratio of NADH and FAD of cancerous cells was also shown to be larger than that of normal cells.

Enhanced Dissociation of Hot Excitons with an Applied Electric Field under Low-Power Photoexcitation in Two-Dimensional Perovskite Quantum Wells

The dependence of photoluminescence (PL) on excitation power and the effect of an external electric field have been studied for a two-dimensional (2D) perovskite (C₄H₉NH₃)₂PbI₄ thin-film sample. The efficiency of dissociation of hot excitons to produce free carriers was enhanced with a small excitation power because the relaxation of hot excitons to cold emissive excitons was slow, indicating that the thermal energies of hot carriers can be utilized in solar cells under weak photoirradiation. The dissociation was notably enhanced with an applied electric field, resulting in efficient field-induced quenching of the PL. The present results shed light on an application of 2D perovskite materials to photovoltaic (PV) devices with dim radiation, e.g., for indoor PV applications; the concept of electric field-assisted solar cells might be applicable to next-generation solar cells.

Fluorescence enhancement induced by quadratic electric-field effects on singlet exciton dynamics in poly(3-hexylthiophene) dispersed in poly(methyl methacrylate)

The dynamics of the exciton generated by photoexcitation of a regioregular poly(3-hexylthiophene) (P3HT) polymer dispersed in a poly(methyl methacrylate) (PMMA) matrix was examined using electro-photoluminescence (E-PL) spectroscopy, where electric field effects on the photoluminescence (PL) spectra were measured. The quadratic electric-field effect was investigated using the modulation technique, with field-induced changes in the PL intensity monitored at the second harmonic of the modulation frequency of the applied electric field. Absorption and PL spectra indicated the formation of both ordered crystalline aggregates and amorphous regions of P3HT polymer chains. Although previous studies of electric field effects on π-conjugated polymers have generally shown that the PL intensity is decreased by electric fields, we report that the PL intensity of P3HT and PL lifetime increased with the quadratic electric-field effect. The magnitude of the change in PL intensity was quantitatively explained in terms of the field-induced decrease in the nonradiative decay rate constants of the exciton. We proposed that a delayed PL, originating from charge carrier recombination, was enhanced in the presence of electric fields. The rate constant of the downhill relaxation process of the exciton, which originated from the relaxation in distributed energy levels due to an inherent energetic disorder in P3HT aggregates, was implied to decrease in the presence of electric fields. The radiative decay rate constant and PL quantum yield of P3HT dissolved in solution, which were evaluated from the molar extinction coefficient and the PL lifetime, were compared with those of P3HT dispersed in a PMMA matrix.

Effects of Nanosecond Pulsed Electric Field on Intracellular NADH Autofluorescence: A Comparison between Normal and Cancer Cells

Intracellular fluorescence lifetime and intensity images of the endogenous fluorophore of nicotinamide adenine dinucleotide (NADH) have been observed before and after application of nanosecond pulsed electric field (nsPEF) in normal and cancer cells, that is, in Wistar-King-Aptekman rat fetus fibroblast (WFB) cells and W31 cells, which are the malignant transformed cells from WFB. The application of nsPEF induces a change both in intensity and lifetime of NADH, indicating that the intracellular function is affected by application of nsPEF in both normal and cancer cells. The application of nsPEF induces an increase in the fluorescence lifetime of NADH and a morphological change, which is attributed to the induction of apoptosis by nsPEF. The field effect on the intensity and lifetime clearly depends on the pulse width, and magnitude of the field-induced increase in the fluorescence lifetime of NADH has a tendency to increase with a decreasing pulse width. It is also found that apoptosis can be induced only in cancer cells using a suitable nsPEF, showing a possibility that ultrashort pulsed electric field is applicable for drug-free cancer therapy.

Identification of a Plasmid-Mediated Quinolone Resistance Gene in Salmonella Isolates from Texas Dairy Farm Environmental Samples

A recent increase in plasmid-mediated quinolone resistance (PMQR) has been detected among Salmonella isolated from humans in the United States, and it is necessary to determine the sources of human infection. We had previously isolated Salmonella from dairy farm environmental samples collected in Texas, and isolates were tested for anti-microbial susceptibility. Two isolates, serotyped as Salmonella Muenster, showed the discordant pattern of nalidixic acid susceptibility and intermediate susceptibility to ciprofloxacin. For this project, whole-genome sequencing of both isolates was performed to detect genes associated with quinolone resistance. The plasmid-mediated qnrB19 gene and IncR plasmid type were identified in both isolates. To our knowledge, this is the first report of PMQR in Salmonella isolated from food animals or agricultural environments in the United States.

Effects of Nanosecond Pulsed Electric Fields on the Intracellular Function of HeLa Cells As Revealed by NADH Autofluorescence Microscopy

The fluorescence lifetime of the endogenous fluorophore of reduced nicotinamide adenine dinucleotide (NADH) in HeLa cells is affected by the application of nanosecond pulsed electric fields (nsPEFs). In this study, we found that after nsPEF application, the fluorescence lifetime became longer and then decreased in a stepwise manner upon further application, irrespective of the pulse width in the range of 10-50 ns. This application time dependence of the NADH fluorescence lifetime is very similar to the time-lapse dependence of the NADH fluorescence lifetime following the addition of an apoptosis inducer, staurosporine. These results, as well as the membrane swelling and blebbing after the application of nsPEFs, indicate that apoptosis is also induced by the application of nsPEFs in HeLa cells. In contrast to the lifetime, the fluorescence intensity remarkably depended on the pulse width of the applied nsPEF. When the pulse width was as large as 50 ns, the intensity monotonically increased and was distributed over the entire cell as the application duration became longer. As the pulse width of the applied electric field became smaller, the magnitude of the field-induced increase in NADH fluorescence intensity decreased; the intensity was reduced by the electric field when the pulse width was as small as 10 ns. These results suggest that the mechanism of electric-field-induced apoptosis depends on the pulse width of the applied nsPEF.

Sensing of intracellular environments by fluorescence lifetime imaging of exogenous fluorophores

Fluorescence lifetime imaging (FLIM) has been recognized as a powerful microscopy technique to examine environments in living systems. The fluorescence lifetime does not depend on the photobleaching and optical conditions, which allows us to obtain quantitative information on intracellular environments by analyzing the fluorescence lifetime. A variety of exogenous fluorophores have been applied in FLIM measurements to examine cellular processes. Information on the correlation between the fluorescence lifetime and the physiological parameters is essential to elucidate the cellular environments from the fluorescence lifetime measurements of exogenous fluorophores. In this review, exogenous fluorophores used for lifetime-based sensing are summarized, with the expectation that it becomes a basis for selecting the fluorophore used to investigate the intracellular environment with FLIM. Experimental results of the intracellular sensing of pH, metal ions, oxygen, viscosity, and other physiological parameters on the basis of the FLIM measurements are described along with a brief explanation of the mechanism of the change in the fluorescence lifetime.

Fluorescence characteristics and lifetime images of photosensitizers of talaporfin sodium and sodium pheophorbide a in normal and cancer cells

Fluorescence spectra and fluorescence lifetime images of talaporfin sodium and sodium-pheophorbide a, which can be regarded as photosensitizers for photodynamic therapy, were measured in normal and cancer cells. The reduction of the fluorescence intensity by photoirradiation was observed for both photosensitizers in both cells, but the quenching rate was much faster in cancer cells than in normal cells. These results are explained in terms of the excessive generation of reactive oxygen species via photoexcitation of these photosensitizers in cancer cells. The fluorescence lifetimes of both photosensitizers in cancer cells are different from those in normal cells, which originates from the different intracellular environments around the photosensitizers between normal and cancer cells.

Electroabsorption spectra of push–pull porphyrins in solution and in solid films

Polarized electroabsorption (E-A) spectra of highly efficient porphyrin sensitizers (YD2 and YD2-oC8) have been measured in benzene solution. Polarized E-A spectra of these push–pull porphyrins embedded in poly(methyl methacrylate) films or sensitized on TiO 2 films are also observed. Based on the analysis of the E-A spectra, the magnitude of the electric dipole moment both in the ground state and in the lowest excited state have been evaluated in solution and in solid films. The electric dipole moment in the excited state of these compounds is very large on TiO 2 films, suggesting the interfacial charge transfer on TiO 2 surface following photoexcitation of porphyrin dyes. The electric dipole moment in the excited state evaluated from the E-A spectra is very different from the one evaluated from the electrophotoluminescence spectra on TiO 2, suggesting that the strong local field of TiO 2 films is applied to the fluorescing dyes attached to TiO 2 films.

Hookworm-related cutaneous larva migrans in patients living in an endemic community in Brazil: immunological patterns before and after ivermectin treatmen

Hookworm-related cutaneous larva migrans (Hr-CLM) is caused by animal hookworm larvae migrating in the human epidermis where they elicit an inflammatory response. This study describes the immunological profile in Hr-CLM patients. In 77 Hr-CLM patients from Manaus, Brazil, peripheral eosinophils were counted, and serum concentrations of total immunoglobulin E (IgE) and selected cytokines were determined by ELISA before and after treatment with ivermectin. Controls included patients' household members (endemic controls), non-endemic Brazilian and Japanese individuals. Eosinophil counts and total IgE in Hr-CLM patients were higher than in controls and correlated with disease severity. Concentrations of interleukin (IL)-4, IL-5, IL-6, and IL-10 were higher in Hr-CLM patients than in endemic controls (p < 0.001) while no differences were detected for interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-1β, IL-2, or transforming growth factor (TGF)-β. Following ivermectin treatment, numbers of eosinophils and concentrations of IL-4, IL-5, and IL-10 decreased whereas IgE, IFN-γ, and TGF-β concentrations increased. The IL-5/IFN-γ ratio declined from 5.9 (interquartile range [IQR] 0.8-31.6) before to 0.1 (IQR 0.05-0.2; p = 0.001) after treatment. Thus, although an impact of other infections on the immune parameters determined cannot be excluded, Hr-CLM in endemic areas is associated with eosinophilia and elevated cytokine levels, particularly of IL-5 and IL-10, which decrease following ivermectin treatment.

The antibody responses to adult-worm antigens ofSchistosoma haematobium, among infected and resistant individuals from an endemic community in southern Ghana

Antibody responses to antigens from adult Schistosoma haematobium were investigated in an endemic community in Ghana, using microplate-ELISA. The results of a survey of egg output in urine and of a questionnaire-based investigation of water-contact activities were used to select 'endemic normal' (EN) and patently infected (PI) individuals as subjects. The plasma levels of antibodies reacting with the adult-worm antigens were determined and compared and the correlations between these levels and the age, water-contact index and egg output of each subject were evaluated. Compared with the EN subjects, the PI generally had higher levels of anti-worm IgG and IgE but lower levels of anti-worm IgA. When the data for the EN and PI groups were combined, the levels of anti-worm IgG and IgE were found to be positively correlated with egg output and with each other. Whichever the antibody class considered, levels of anti-worm antibodies were never negatively correlated with egg output. These results indicate that anti-worm IgE and IgG could be used as markers to reflect current infection intensity, and that anti-worm antibodies may not act as protective antibodies in the natural course of urinary schistosomiasis.

pH dependence of the fluorescence lifetime of FAD in solution and in cells

We have studied physiological parameters in a living cell using fluorescence lifetime imaging of endogenous chromophores. In this study, pH dependence of the fluorescence lifetime of flavin adenine dinucleotide (FAD), that is a significant cofactor exhibiting autofluorescence, has been investigated in buffer solution and in cells. The fluorescence lifetime of FAD remained unchanged with pH 5 to 9 in solution. However, the fluorescence lifetime in HeLa cells was found to decrease with increasing intracellular pH, suggesting that pH in a single cell can be estimated from the fluorescence lifetime imaging of FAD without adding exogenous fluorescent probes.

Application of nanosecond pulsed electric fields into HeLa cells expressing enhanced green fluorescent protein and fluorescence lifetime microscopy

An electrode microchamber has been constructed for applying nanosecond pulsed strong electric fields to living cells, and fluorescence lifetime microscopy (FLIM) has been used to investigate the effects of external electric fields on dynamics and function of HeLa cells expressing enhanced green fluorescent protein (EGFP). Both morphological change in cells and reduction of the fluorescence lifetime of EGFP have been observed after application of electric fields having a pulsed width of 50 ns and a strength of 4 MV m(-1), indicating that apoptosis, which is a programmed cell death, was induced by nanosecond pulsed electric fields and that fluorescence lifetime of EGFP decreased along with the induction of apoptosis. The reduction of the fluorescence lifetime occurred before the morphological change, indicating that FLIM provides a sensitive and noninvasive detection of the progress of apoptosis induced by application of nanosecond pulsed electric fields.

pH-dependent network formation of quantum dots and fluorescent quenching by Au nanoparticle embedding

A simple approach to the creation of colloidal assemblies is in high demand for the development of functional devices. Here, we present the preparation of CdTe-QD (quantum dot) networks in as little as 1 day simply by pH modification without the use of oxidants. The QD network was tractable in water and casting from a droplet produced a porous networked film on both hydrophobic and hydrophilic solid substrates. Further, we found that citrate-protected gold nanoparticles (AuNPs, d = 5 nm) could be incorporated into the QD networks to afford a QD/Au composite network, and that the fluorescence from the QDs was largely decreased by the addition of a small proportion of AuNPs (QD:AuNP = 99.4:0.6), probably due to the efficient charge transfer through the network. These data indicate that our method is suitable for application to the creation of metal/QD hybrid materials that can be integrated into wet-based processes.

Intracellular pH sensing using autofluorescence lifetime microscopy

Fluorescence lifetime images of reduced nicotinamide adenine dinucleotide (NADH) that is a key cofactor in cellular metabolism were obtained in a cell at various values of intracellular pH. The average fluorescence lifetime of NADH is found to become shorter monotonically with increasing pH, indicating that pH in a single cell can be determined by fluorescence lifetime imaging of NADH without adding exogenous fluorescent probes. The magnitude of the pH-induced lifetime change is higher in cells than that in buffer solution. The fluorescence lifetime of NADH is not uniform inside a cell; the fluorescence lifetime of nuclear NADH is shorter than that of mitochondrial NADH at each pH, and the magnitude of the pH-induced change is larger in nuclei than in other areas. The local electric field effect on the fluorescence lifetime is discussed since this effect may be one of the strong possibilities for the nonuniformity of the autofluorescence lifetime of NADH in cells.

Fluorescence decay dynamics of flavin adenine dinucleotide in a mixture of alcohol and water in the femtosecond and nanosecond time range

Fluorescence decays of flavin adenine dinucleotide (FAD) that is a typical autofluorescent species in cells and tissues have been measured in a mixture of alcohol and water in the femtosecond and nanosecond time range. The fluorescence lifetimes of both the stacked conformation between the isoalloxazine and adenine moieties in close proximity and the extended open conformation in water are affected by the addition of alcohol. The nanosecond fluorescence lifetime of the open conformation increases with decreasing dielectric constant of the medium, contributing to the enhancement of the fluorescence intensity of FAD in less dielectric media. The fluorescence lifetime of the open conformation is also affected by medium viscosity, suggesting that the photoexcited open conformation is quenched by the dynamic interaction between the two aromatic rings. The fluorescence component decaying in tens of picoseconds is attributed to the stacked conformation that shows the efficient fluorescence quenching due to the intramolecular electron transfer. The picosecond fluorescence lifetime of the stacked conformation increases with decreasing dielectric constant, suggesting the shift of the distribution of the stacked conformation to a longer intramolecular distance between the two aromatic rings in less dielectric media. The pre-exponential factor of the picosecond decaying component relative to that of the nanosecond one decreases with the increase of the alcohol concentration in the femtosecond time-resolved fluorescence, which demonstrates the increase in the population of the open conformation with the reduction of the dielectric constant. The possibility to evaluate the polar environment in a cell by the fluorescence lifetime of FAD is discussed based on the results obtained.

Loop-mediated isothermal amplification assay for detection and discrimination of Toxocara canis and Toxocara cati eggs directly from sand samples

We developed a novel and simple method, using loop-mediated isothermal amplification (LAMP), for the detection and discrimination of Toxocara canis and Toxocara cati eggs. The new method employs 4 steps: (1) concentration of Toxocara eggs in a small amount of sand; (2) dissolution of the proteinaceous membrane of eggs and simultaneously separation of them from the sand using NaClO treatment; (3) extraction of DNA using NaOH treatment; and (4) detection of T. canis / T. cati DNA using a LAMP assay. All these steps are fast, easy to perform, and do not require expensive equipment or reagents. The novel method was tested both experimentally and in a field study. In the laboratory, we could reliably detect as few as 3 T. canis eggs in artificially contaminated sand, if the experiment was repeated twice. In the field trial, we were able to detect T. cati DNA from 4 natural sandpits having moderate to heavy contamination, although not in a single lightly contaminated sandpit. All of the examined sandpits were found to be contaminated with eggs of T. cati, but none appeared to contain T. canis. Our new method could extract DNA from T. canis and T. cati eggs directly from sand samples as well as detect and distinguish these 2 species in a few easy steps, with markedly reduced time and expense.

Formation mechanism studies of phenylene-bridged periodic mesoporous organosilicas (PMOs)

The formation of phenylene-bridged periodic mesoporous organosilicas (PMOs) in the presence of three diblock copolymers differing in hydrophobic hydrocarbon chain lengths was investigated. Hexaethylene glycol octadecylether (C(18)(EO)(6)), hexaethylene glycol hexadecylether (C(16)(EO)(6)), and hexaethylene glycol dodecylether (C(12)(EO)(6)) were chosen in order to obtain insight on the influence of the hydrocarbon chain length on the mesostructure. 1,4-Bis(triethoxysilyl)benzene (BTEB) was used as organosilica precursor under mild acidic conditions. The reactions were followed by in situ small-angle X-ray diffraction (SAXD) on-time in a capillary flow setup. It was found that during the reaction the formation of different structures was observed, which is ascribed to the hydrolysis and condensation of the organosilica precursor. In all cases, different structures evolve with time and phase transitions are observed during the measurements independent of the hydrocarbon chain length.

Theoretical quest for photoconversion molecules having opposite directions of the electric dipole moment in S0 and S1 states

Ab initio calculations at the level of CASPT2 with Dunning's correlation consistent cc-pVXZ (X=D, T, Q) basis sets have been carried out for pyrimidine, quinoxaline, phthalazine, and their substituted compounds to find candidates that show a change in the direction of the electric dipole moment for the S(0)-->S(1) transition. The present calculations reveal that 6,7-difluorophthalazine and 6,7-dichlorophthalazine are strong candidates having a large and clear change in the direction of the electric dipole moment on the S(0)-->S(1) transition.