A novel Y-shaped photoiniferter used for the construction of polydimethylsiloxane surfaces with antibacterial and antifouling properties.

The simultaneous introduction of two new functionalities into the same polymeric substrate under mild reaction conditions is an interesting and important topic. Herein, dual-functional polydimethylsiloxane (PDMS) surfaces with antibacterial and antifouling properties were conveniently developed via a novel Y-shaped asymmetric dual-functional photoiniferter (Y-iniferter). The Y-iniferter was initially immobilized onto the PDMS surface by radical coupling under visible light irradiation. Afterwards, poly(2-hydroxyethyl methacrylate) (PHEMA) brushes and antibacterial ionic liquid (IL) fragments were simultaneously immobilized on the Y-iniferter-modified PDMS surfaces by combining the sulfur(VI)-fluoride exchange (SuFEx) click reaction and UV-photoinitiated polymerization. Experiments using E. coli as a model bacterium demonstrated that the modified PDMS surfaces had both the expected antibacterial properties of the IL fragments and the excellent antifouling properties of PHEMA brushes. Furthermore, the cytotoxicity of the modified PDMS surfaces to L929 cells was examined in vitro with a CCK-8 assay, which showed that the modified surfaces maintained excellent cytocompatibility. Briefly, this strategy of constructing an antibacterial and antifouling PDMS surface has the advantages of simplicity and convenience and might inspire the construction of diverse dual-functional surfaces by utilizing PDMS more effectively.

Sulfone-containing Conjugated Polyimide 2D Nanosheets for Efficient Water Oxidation.

Water oxidation is a bottleneck in artificial photosynthesis that impedes its practicality for solar energy conversion and utilization. It is highly desired to significantly improve the efficacy of the existing catalysts or to rationally design new catalysts with improved performance. We report a novel conjugated and sulfone containing polyimide as a metal-free photocatalyst synthesized via a two-step method: (i) synthesis of precursor poly(amic acid) (PAA) (ii) solvothermal synthesis of polyimide through thermal imidization. The synthesis of the polyimide photocatalyst was demonstrated by the amide linkage in the FTIR spectrum. The obtained photocatalyst was semicrystalline in nature and possessed sheet-like morphology as illustrated by the diffraction pattern and the electron micrographic images, respectively. The thermogravimetric analysis of the polyimide nanosheets validated a thermally stable structure. The DFT calculations were performed which showed a suitable HOMO band position, favorable for water oxidation. The photoelectrocatalytic (PEC) performance of the polyimide nanosheets evaluated by studying water oxidation reaction without any sacrificial agent under 1-SUN showed enhanced PEC performance and good stability towards water oxidation at 0 V versus SCE.

Evaluation of the migration of chemicals from baby bottles under standardised and duration testing conditions.

After the prohibition of bisphenol-A-containing polycarbonate baby bottles in the European Union (EU), alternative materials, such as polypropylene, polyethersulphone, Tritan™ copolyester, etc., have appeared on the market. Based on an initial screening and in vitro toxicity assessment, the most toxic migrating compounds were selected to be monitored and quantified using validated GC- and LC-QqQ-MS methods. The effect of several 'real-life-use conditions', such as microwave, sterilisation and dishwasher, on the migration of different contaminants was evaluated by means of duration tests. These results were compared with a reference treatment (filling five times with pre-heated simulant at 40°C) and with the legal EU 'repetitive-use conditions' (three migrations, 2 h at 70°C). Analysis of the third migration step of the EU repetitive-use conditions (which has to comply with the EU legislative migration limits) showed that several non-authorised compounds were observed in some baby bottles exceeding 10 µg kg(-1). However, all authorised compounds were detected well below their respective specific migration limits (SMLs). The reference experiment confirmed the migration of some of the compounds previously detected in the EU repetitive-use experiment, though at lower concentrations. Analysis of extracts from the microwave and dishwasher experiments showed a reduction in the migration during the duration tests. In general, the concentrations found were low and comparable with the reference experiment. Similar observations were made for the two sterilisation types: steam and cooking sterilisation. However, steam sterilisation seems to be more recommended for daily use of baby bottles, since it resulted in a lower release of substances afterwards. Repeated use of baby bottles under 'real-life' conditions showed no increase in the migration of investigated compounds and, after some time, the migration of these compounds even became negligible.

Investigation on the capability of polysulphone for measuring biologically effective solar UV exposures.

Polysulphone (PS) dosimetry is a well-known technique broadly used to assess the erythemally effective solar UV dose received by anatomical sites (personal exposure). We investigate the capability of PS dosimetry to convert doses absorbed by PS badges into biologically effective solar UV exposures taking as examples two relevant effects for human skin: erythema induction and pre-vitamin D3 production. PS calibration curves for erythemal and pre-vitamin D3 were distinctly determined by using an empirical relationship between the biologically effective UV exposures and the PS absorbance change. This relationship is parameterized by a coefficient, distinct for each of the two considered biological effects, multiplying the same cubic polynomial function. It is shown how the multiplying coefficient is related to the ratio between the biologically effective and the PS weighted irradiances which is the prevailing factor affecting the accuracy of the calibration and, consequently, the capability of PS films for measuring biologically effective solar UV exposures. The points addressed in this paper can be extended to other biological effects of interest whose action spectra have some similarity with the PS film response.

Ultrasound irradiation combined with hydraulic cleaning on fouled polyethersulfone and polyvinylidene fluoride membranes.

In this study, an ultrasonic irradiation technique was utilized to mitigate the fouling of polyethersulfone (PES) and polyvinylidene fluoride (PVDF) membranes. The use of ultrasound at 20 kHz was applied to a dead-end microfiltration cell in order to mitigate fouling caused by the presence of colloidal bentonite particles. The effect of ultrasonic power and pulse duration on the permeate flux recovery was examined. Measurements indicate that an increase in ultrasonic power and longer pulse duration results to a higher permeate flux recovery. In order to reduce power consumption, a low to high power shift (LHPS) and pulsation method, were investigated. Methods of cleaning such as ultrasonic irradiation, ultrasonic cleaning with forward flushing and ultrasonic cleaning with backwashing were utilized and their cleaning efficiencies were examined. The cleaning performance was assessed using the clean water flux method and scanning electron microscope analysis of the cleaned membranes. Results showed that LHPS and pulsation method both improve the permeate flux recovery but were not able to attain the 93.97 and 74.88% flux recovery for PES and PVDF that was achieved by constant-15 W ultrasonic cleaning. In addition, forward flushing and backwashing may enhance the performance of ultrasonic cleaning at 9 W but could become disadvantageous at 15 W.

Identification of phototransformation products of sildenafil (Viagra) and its N-demethylated human metabolite under simulated sunlight.

Recent publications on pharmaceutical monitoring are increasingly covering the field of illicit drugs and lately the forensic evaluation of designing illegal analogs of lifestyle drugs like the phosphodiesterase type 5 (PDE-5) inhibitors Viagra (sildenafil), Levitra (vardenafil) and Cialis (tadalafil). Recently, the presence of all three erectile dysfunction treatment drugs has been reported in wastewaters at very low concentrations. In the environment, contaminants undergo various physical or chemical processes classified into abiotic (photolysis, hydrolysis) and biotic (biodegradation) reactions. Thus, changes in the chemical structure lead to the formation of new transformation products, which may persist in the environment or be further degraded. This study describes the photolysis of sildenafil (SDF) and its human metabolite N-demethylsildenafil (DM-SDF) under simulated solar radiation (Xenon lamp). Following chromatographic separation of the irradiated samples, eight photoproducts in the SDF samples and six photoproducts for DM-SDF were detected and characterized. The combination of ultra performance liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry (UPLC-ESI-QToF-MS), liquid chromatography-atmospheric pressure chemical ionization-triple quadrupole mass spectrometry (LC-APCI-QqQ-MS) and hydrogen/deuterium-exchange experiments allowed to propose plausible chemical structures for the photoproducts, taking into account the characteristic fragmentation patterns and the accurate mass measurements. These mass spectral data provided sound evidence for the susceptibility of the piperazine ring toward photodegradation. A gradual breakdown of this heterocyclic structure gave rise to a series of products, which in part were identical for SDF and DM-SDF. The sulfonic acid, as the formal product of sulfonamide hydrolysis, was identified as key intermediate in the photolysis pathway. In both drug/metabolite molecules, phototransformation processes taking place beyond the sulfonamide group were deemed to be of minor relevance.

Effect of light and pH on persistence of flubendiamide.

Persistence of flubendiamide in soil as affected by UV and sunlight exposure and in water as affected by pH was studied. At field capacity moisture regime, soil was treated with flubendiamide and exposed to UV and sunlight. Dissipation for the pesticide followed mono-phasic first order kinetics. Residues of flubendiamide, as thin film on petri-plates and soil thin film, dissipated with half-lives of 7.0 and 9.1 days under UV light and 12.0 and 19.1 days under sunlight, respectively. Residues of flubendiamide dissipated faster under UV light as compared to sunlight. Persistence study in aqueous medium under different pH condition indicated that flubendiamide residues persisted in water beyond 250 days with half-lives ranging from 250.8 to 301.0 days. Dissipation in water was faster at pH 4.0 (T(1/2) 250.8 days), followed by pH 9.2 (T(1/2) 273.6 days) and 7.0 (T(1/2) 301.0 days).

Ultrasound promoted synthesis of substituted pyrazoles and isoxazoles containing sulphone moiety.

Novel pyrazoles and isoxazoles were synthesized from the reaction of the carbanions of 1-aryl-2-(phenylsulphonyl)-ethanone with different hydrazonyl halides and 1-aryl-2-bromo-2-hydroximinoethanone in ethanol, respectively. Reactions were carried out under silent and ultrasonic conditions. In general, it was found that ultrasound irradiations enable some reactions to occur which could not be carried out under silent condition in addition to improvement in reaction times. The products were obtained in high yields and their structures were determined by elemental analyses, spectral data and X-ray diffraction.

Effects of gamma-irradiation on physical and biologic properties of crosslinked hyaluronan tissue engineering scaffolds.

Hydrogels containing divinyl sulfone (DVS)-crosslinked hyaluronan (HA) (hylans) are potentially useful implant biomaterials because of their non-cytotoxicity and -antigenicity. However, to successfully fulfill their intended role in vivo, their properties (e.g., mechanics, pore size, surface topography, hydrophilicity, swelling) must be modulated to match the demands of the target application. This study explored whether controlled irradiation with gamma (gamma) can strengthen hylans and modulate their physical and biologic properties, as has previously been shown to be possible with other natural and synthetic polymers. Hydrated hylans containing two different amounts of DVS were irradiated in vacuum to increasing doses of gamma (0-13.5 kGy). The properties of the irradiated gels were compared with those of non-irradiated controls. Changes to bulk structure were evaluated using swelling tests, surface topography and pore structure were evaluated using scanning electron microscopy, mechanics were evaluated using unconfined compression tests, and surface hydrophilicity was evaluated by measuring contact angle changes. Irradiated gels exhibited lower swelling capacity, structural weakening, increase in elasticity, surface texturing, increased pore size, and decreased surface hydrophilicity in direct correlation with received dose. Cells adhered and proliferated readily on the irradiated gel surfaces but not on control gels. The irradiated gels, however, deteriorated during long-term (<60 days) storage. Irradiation of hylans in a lyophilized state instead resulted in gels that were more compact, swelled less, and exhibited smaller pores than their hydrated counterparts. The results show that gamma-irradiation, although useful to modulate hylan gel properties, presents challenges of degradation that may be associated with its generation of free-radicals, HA chain fragmentation, and disruption of DVS crosslinks, particularly when the gels are irradiated in their native hydrated state (>98% water content). Future studies will optimize parameters for gamma-mediated modulation of hylan properties through irradiation under water-free conditions.

Pre-column derivatization of rofecoxib for determination in serum by HPLC.

An HPLC method for determination of rofecoxib in human serum is presented. The method is based on pre-column derivatization of analyte to a phenanthrene derivative of the drug. Rofecoxib and the internal standard were extracted from serum using liquid-liquid extraction. Upon exposure to UV light, the drug was found to undergo a photocyclization reaction, giving a species with high absorbance. Validation of the method has been studied in the concentration range 10-500 ng ml(-1).

Free electron laser induces specific immobilization of heparin on polysulfone films.

Covalent immobilization of heparin has been developed to reduce the amount of heparin administered systematically during long-term dialysis. Recently, it was doubted partially because of the complexion during immobilization process. In this study, we investigated a novel method for specific immobilization of heparin on polysulfone (PSF) via free electron laser (FEL) irradiation. Laser wavelengths of 6.18 or 6.31 microm, the typical absorption bands of carboxyl groups of heparin and aromatic rings in PSF, respectively, were chosen to irradiate the thin heparin membrane formed on PSF surfaces. The amount of heparin immobilized on PSF was measured by the toluidine blue method. The binding of heparin on PSF was analyzed by X-ray photoelectron spectroscopy (XPS). The immobilization of heparin resulted in a hydrophilic surface on which decreased platelet adhesion was observed. The efficiency differences, depending on laser wavelengths, were discussed from the point of view of structural and environmental differences of light-absorbing groups.

Photocleavage coupling reactions between cyclohexa-2,4-dienone sulfone derivatives and amines by visible light irradiation.

A stable sulfone derivative of 2,4,6-trimethylcyclohexa-2,4-diene-1-one (7) undergoes facile ring cleavage under visible light to produce a ketene intermediate, which could be efficiently captured by amines to give amides even in the presence of competing nucleophiles such as water and ethanol.

Assessment of the dose response of polysulphone film badges for the measurement of UV-radiation.

The dose response and accuracy of polysulphone film badges for monitoring UVB radiation (280-315 nm) were assessed by spectroradiometric measurements of the radiation source. A new formula is presented to calculate the UVB exposure of film badges. It is based on absorbance change at 330 nm and takes into account the saturation of the optical density of the badges. A good correlation was found between measured and radiated dose. Differences from previous formulae and limitations of the polysulphone films are discussed.