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Microorganisms Dec 2023Antibiotic-free approaches are more important than ever to address the rapidly growing problem of the antibiotic resistance crisis. The photolysis of the bacterial...
Antibiotic-free approaches are more important than ever to address the rapidly growing problem of the antibiotic resistance crisis. The photolysis of the bacterial virulence factor staphyloxanthin using blue light at 460 nm (BL460 nm) has been found to effectively attenuate to chemical and physical agents. However, phototherapy using BL640 nm still needs to be investigated in detail for its safety in eradicating in vitro and in vivo. In this study, we employed a 460 nm continuous-wavelength LED source and a low concentration of hydrogen peroxide to treat under a culturing condition and a wound abrasion mouse model. The results demonstrated the safety of the combined therapy when it did not modify the bacterial virulence factors or the susceptibility to widely used antibiotics. In addition, the results of the mouse model also showed that the combined therapy was safe to apply to mouse skin since it did not cause adverse skin irritation. More importantly, the therapy can aid in healing -infected wounds with an efficacy comparable to that of the topical antibiotic Fucidin. The aforementioned findings indicate that the concurrent application of BL460 nm and hydrogen peroxide can be used safely as an alternative or adjunct to antibiotics in treating -infected wounds.
PubMed: 38138090
DOI: 10.3390/microorganisms11122946 -
Chemosphere Feb 2024In this study, the performance of standalone ultraviolet (UV) photolysis and UV-based advanced oxidation processes (AOPs), namely, UV/hydrogen peroxide, UV/chlorine,...
In this study, the performance of standalone ultraviolet (UV) photolysis and UV-based advanced oxidation processes (AOPs), namely, UV/hydrogen peroxide, UV/chlorine, UV/persulphate, and UV/permonosulphate, were investigated for the degradation of 31 trace organic contaminants (TrOCs). Under the tested conditions, standalone UV photolysis did not achieve effective removal of TrOCs. To improve the degradation efficiency of UV photolysis, four different oxidants were added individually to the test solution. The effect of these oxidants in the absence of UV irradiation was also explored and only chlorine showed promising degradation of some contaminants. During the chlorination of 31 investigated TrOCs, only six demonstrated greater than 50% degradation. The combined UV-based AOPs demonstrated much improved degradation (ranging from 65 to 100%) depending on TrOC-structure and oxidant concentration. The UV/hydrogen peroxide process showed similar degradation of TrOCs, irrespective of the functional groups (i.e., electron withdrawing groups, EWGs and electron donating groups, EDGs) present in their structures. Conversely, the UV/sulphate and UV/chlorine based processes achieved better degradation of the TrOCs with EDGs in their structures. TrOCs degradation improved up to 40% when oxidants concentrations were increased from 0.1 to 1 mM, and further increasing the concentration to 2 mM did not improve degradation. Toxicity evaluation using bioluminescence test (BLT assay) demonstrated that except for UV/hydrogen peroxide, all UV-based AOPs increased the toxicity of the treated effluent, indicating generation of toxic by-products. This study elucidates the performance of four different UV-based AOPs for the removal of commonly detected diverse TrOCs for the first time.
Topics: Hydrogen Peroxide; Chlorine; Water Pollutants, Chemical; Oxidants; Oxidation-Reduction; Photolysis; Ultraviolet Rays; Water Purification
PubMed: 38135125
DOI: 10.1016/j.chemosphere.2023.140978 -
Chemical Science Dec 2023Coordination cage catalysis has commonly relied on the endogenous binding of substrates, exploiting the cavity microenvironment and spatial constraints to engender...
Coordination cage catalysis has commonly relied on the endogenous binding of substrates, exploiting the cavity microenvironment and spatial constraints to engender increased reactivity or interesting selectivity. Nonetheless, there are issues with this approach, such as the frequent occurrence of product inhibition or the limited applicability to a wide range of substrates and reactions. Here we describe a strategy in which the cage acts as an exogenous catalyst, wherein reactants, intermediates and products remain unbound throughout the course of the catalytic cycle. Instead, the cage is used to alter the properties of a cofactor guest, which then transfers reactivity to the bulk-phase. We have exemplified this approach using photocatalysis, showing that a photoactivated host-guest complex can mediate [4 + 2] cycloadditions and the aza-Henry reaction. Detailed photolysis experiments show that the cage can both act as a photo-initiator and as an on-cycle catalyst where the quantum yield is less than unity.
PubMed: 38098714
DOI: 10.1039/d3sc04877b -
Environmental Science and Pollution... Jan 2024Given the immense threats of microplastics, we herein investigate photodegrading the debris of polyethylene bags (PBs) by sulfur-doped titanium dioxide. The optimization...
Given the immense threats of microplastics, we herein investigate photodegrading the debris of polyethylene bags (PBs) by sulfur-doped titanium dioxide. The optimization of operating parameters showed that controlling the water pH at 3 and introducing PBs by 0.10 g/L under a catalyst dose of 1.25 g/L reduced the polyethylene mass by 3.10% in 7 h, whereas raising the catalyst dose to 3 g/L improved the mass reduction to 4.72%. The extension of degradation time to 100 h at pH 3, catalyst dosage of 3 g/L, and PBs concentration of 0.10 g/L increased the mass loss ratio to 21.74%. Scanning electron microscopy of PBs after 100 h of photodegradation showed cracks on the surface accompanied by the increase of carbonyl index from 0.52 to 1.41 confirming the breakdown of the polymeric chain. Total organic carbon increased from 0.80 to 7.76 mg/L in the first 10 h of photodegradation, then decreased to 1 mg/L after extending the reaction time to 100 h due to the mineralization of organic intermediates generated from the photodegradation of PBs. Trapping tests exhibited the major role of hydroxyl radicals in the degradation system, and the catalyst showed high stability under five repetitive runs. This study proposes an efficient treatment system that can be implemented on a wider scale utilizing the synthesized catalyst to degrade plastics efficiently before their release to water streams.
Topics: Photolysis; Polyethylene; Water; Plastics; Water Pollutants, Chemical; Titanium; Catalysis
PubMed: 38097836
DOI: 10.1007/s11356-023-31460-1 -
Chemical Communications (Cambridge,... Jan 2024Photocleavable protecting groups (PPGs) enable the light-induced, spatiotemporal control over the release of a payload of interest. Two fundamental challenges in the...
Photocleavable protecting groups (PPGs) enable the light-induced, spatiotemporal control over the release of a payload of interest. Two fundamental challenges in the design of new, effective PPGs are increasing the quantum yield (QY) of photolysis and red-shifting the absorption spectrum. Here we describe the combination of two photochemical strategies for PPG optimization in one molecule, resulting in significant improvements in both these crucial parameters. Furthermore, we for the first time identify the process of photo-isomerization to strongly influence the QY of photolysis of a PPG and identify the -isomer as the superior PPG.
PubMed: 38095129
DOI: 10.1039/d3cc05055f -
Chemical Science Dec 2023The synthesis of benzylboronates by photochemical homologation of boronic acids with -tosylhydrazones under basic conditions is described. The reaction involves the...
The synthesis of benzylboronates by photochemical homologation of boronic acids with -tosylhydrazones under basic conditions is described. The reaction involves the photolysis of the -tosylhydrazone salt to give a diazoalkane followed by the geminal carboborylation of the diazoalkane. Under the mild reaction conditions, the protodeboronation of the unstable benzylboronic acid is circumvented and the pinacolboronates can be isolated after reaction of the benzylboronic acid with pinacol. The metholodogy has been applied to the reactions of alkylboronic acids with -tosylhydrazones of aromatic aldehydes and ketones, and to the reactions of arylboronic acids with -tosylhydrazones of aliphatic ketones. Moreover, the employment of the DBU/DIPEA bases combination allows for homogeneous reactions which have been adapted to photochemical continuous flow conditions. Additionally, the synthetic versatility of boronates enables their further transformation Csp-C or Csp-X bond forming reactions converting this methodology into a novel method for the geminal difunctionalization of carbonyls -tosylhydrazones.
PubMed: 38075646
DOI: 10.1039/d3sc05678c -
The Science of the Total Environment Feb 2024The decolorization and TOC removal of solutions of Acid Brown 14 (AB14) diazo dye containing 50 mg L of total organic carbon (TOC) have been first studied in a...
The decolorization and TOC removal of solutions of Acid Brown 14 (AB14) diazo dye containing 50 mg L of total organic carbon (TOC) have been first studied in a continuous-flow electrocoagulation (EC) reactor of 3 L capacity with Fe electrodes of ∼110 cm area each. Total loss of color with poor TOC removal was found in chloride, sulfate, and/or hydrogen carbonate matrices after 18 min of this treatment. The best performance was found using 5 anodes and 4 cathodes of Fe at 13.70 A and low liquid flow rate of 10 L h, in aerated 39.6 mM NaCl medium within a pH range of 4.0-10.0. The effluent obtained from EC was further treated by electro-Fenton (EF) using a 2.5 L pre-pilot flow plant, which was equipped with a filter-press cell comprising a Pt anode and an air-diffusion cathode for HO electrogeneration. Operating with 0.10-1.0 mM Fe as catalyst at pH 3.0 and 50 mA cm, a similar TOC removal of 68 % was found as maximal in chloride and sulfate media using the sequential EC-EF process. The EC-treated solutions were also treated by photoelectro-Fenton (PEF) employing a photoreactor with a 125 W UVA lamp. The sequential EC-PEF process yielded a much higher TOC reduction, close to 90 % and 97 % in chloride and sulfate media, respectively, due to the rapid photolysis of the final Fe(III)-carboxylate complexes. The formation of recalcitrant chloroderivatives from generated active chlorine limited the mineralization in the chloride matrix. For practical applications of this two-step technology, the high energy consumption of the UVA lamp in PEF could be reduced by using free sunlight.
PubMed: 38070549
DOI: 10.1016/j.scitotenv.2023.169143 -
Molecules (Basel, Switzerland) Nov 2023Electron Beam (EB) irradiation was utilized to decontaminate model systems of industrial polymers that contain a brominated flame retardant (BFR)....
Electron Beam (EB) irradiation was utilized to decontaminate model systems of industrial polymers that contain a brominated flame retardant (BFR). Acrylonitrile-butadiene-styrene (ABS) and Polycarbonate (PC) are two types of polymers commonly found in Waste Electrical and Electronic Equipment (WEEE). In this study, these polymers were exposed to EB irradiation to degrade DecaBromoDiphenylEther (DBDE), one of the most toxic BFRs. Fourier-transform infrared spectroscopy analysis demonstrated an 87% degradation rate of DBDE for the ABS-DBDE system and 91% for the PC-DBDE system following an 1800 kGy irradiation dose. Thermal analysis using Differential Scanning Calorimetry revealed the presence of crosslinking in ABS and a minor reduction in the glass transition temperature of PC after EB processing. Polymers exhibited thermal stability after photolysis, as indicated by thermogravimetric analysis. In summary, EB irradiation had no impact on the overall thermal properties of both polymers. High-resolution mass spectrometry analysis has confirmed the debromination of both ABS-DBDE and PC-DBDE systems. Therefore, the results obtained are promising and could offer an alternative approach for removing bromine and other additives from plastic E-waste.
PubMed: 38067482
DOI: 10.3390/molecules28237753 -
Environmental Science & Technology Dec 2023Dissolved organic matter (DOM) holds the largest amount of organic carbon in the ocean, with most of it residing in the deep for millennia. Specific mechanisms and...
Dissolved organic matter (DOM) holds the largest amount of organic carbon in the ocean, with most of it residing in the deep for millennia. Specific mechanisms and environmental conditions responsible for its longevity are still unknown. Microbial transformations and photochemical degradation of DOM in the surface layers are two processes that shape its molecular composition. We used molecular data (via Fourier transform ion cyclotron resonance mass spectrometry) from two laboratory experiments that focused on (1) microbial processing of fresh DOM and (2) photodegradation of deep-sea DOM to derive independent process-related molecular indices for biological formation and transformation () and photodegradation (). Both indices were applied to a global ocean data set of DOM composition. The distributions of and were consistent with increased photodegradation and biological reworking of DOM in sunlit surface waters, and traces of these surface processes were evident at depth. Increased values in the deep Southern Ocean and South Atlantic implied export of microbially reworked DOM. Photodegraded DOM (increased ) in the deep subtropical gyres of Atlantic and Pacific oceans suggested advective transport in warm-core eddies. The simultaneous application of and disentangled and assessed two processes that left unique molecular signatures in the global ocean.
Topics: Dissolved Organic Matter; Photolysis; Carbon; Mass Spectrometry; Oceans and Seas
PubMed: 38065573
DOI: 10.1021/acs.est.3c05929 -
Water Research Feb 2024The presence of estrogens in water environments has raised concerns for human health and ecosystems balance. These substances possess potent estrogenic properties,...
The presence of estrogens in water environments has raised concerns for human health and ecosystems balance. These substances possess potent estrogenic properties, causing severe disruptions in endocrine systems and leading to reproductive and developmental problems. Unfortunately, conventional treatment methods struggle to effectively remove estrogens and mitigate their effects, necessitating technological innovation. This study investigates the effectiveness of a novel sequential photolysis-granular activated carbon (GAC) sandwich biofiltration (GSBF) system in removing estrogens (E1, E2, E3, and EE2) and improving general water quality parameters. The results indicate that combining photolysis pre-treatment with GSBF consistently achieved satisfactory performance in terms of turbidity, dissolved organic carbon (DOC), UV, and microbial reduction, with over 77.5 %, 80.2 %, 89.7 %, and 92 % reduction, respectively. Furthermore, this approach effectively controlled the growth of microbial biomass under UV irradiation, preventing excessive head loss. To assess estrogen removal, liquid chromatography-tandem mass spectrometry (LC-MS) measured their concentrations, while bioassays determined estrogenicity. The findings demonstrate that GSBF systems, with and without photolysis installation, achieved over 96.2 % removal for estrogens when the spike concentration of each targeted compound was 10 µg L, successfully reducing estrogenicity (EA/EA0) to levels below 0.05. Additionally, the study evaluated the impact of different thicknesses of GAC layer filling (8 cm, 16 cm, and 24 cm) and found no significant difference (p>0.05) in estrogen and estrogenicity removal among them.
Topics: Humans; Estrogens; Photolysis; Ecosystem; Water Pollutants, Chemical; Estrone; Charcoal
PubMed: 38064783
DOI: 10.1016/j.watres.2023.120976