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Visible-Light-Activated High-Density Materials for Controlled in Vivo Insulin Release
摘要： In this work, we describe the synthesis, characterization, and ultimate in vivo assessment of second-generation insulin photoactivated depot (PAD) materials. These are the first to use visible light to stimulate insulin release and have an in vivo performance that is 28-fold improved relative to first-generation materials. This improvement is due to two major factors linked to the utilized chemistry: (1) we have incorporated the coumarin photo-cleavable group, which increases the photorelease wavelength into the visible range, enhancing tissue penetration of the light; (2) photo-toggling of insulin solubility is produced by linking three insulin molecules to a central bridge via light cleaved groups, and not by bonding to a large polymer. The resulting trimer is, therefore, highly dense (87% insulin dry w/w) but retains the insolubility required of the approach. Only after irradiation with visible light is native, soluble insulin released from the dermal depot. This high density increases the amount and ease of insulin release, as the density of photolytic groups is 10?20-fold higher than in polymer-based first-generation materials. We have synthesized new azide-terminated coumarin linkers that we react with the amine groups of insulin. Using mass spectrometry methods, we identify the sites of reaction and purify individual isomers, which we demonstrate have in vitro photolysis rates that are within a factor of 2 of each other. We then reacted these terminal azide groups with a tridentate strained alkyne linker. We show that the resulting insulin trimer is highly insoluble, but can be milled into injectable particles that release insulin only in response to light from a 406 nm light source. Finally, we demonstrate that these materials have a significantly improved in vivo performance, releasing 28-fold more insulin on a per energy basis than first-generation materials.
关键词： photolysis,protein chemistry,insulin,coumarin,click chemistry
更新于2025-09-23 15:19:57
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Infrared Spectroscopic and Kinetic Characterization on the Photolysis of Nitrite in Alcohol-Containing Aqueous Solutions
摘要： Nitrite is regarded as a potential OH and NO precursor in aqueous solution upon ultraviolet photolysis. A step-scan Fourier-transform interferometer was employed to collect the transient infrared difference spectra upon excitation of the sodium nitrite aqueous solution in the presence of methanol and ethanol upon 355 nm pulsed excitation. The photolytic intermediates were proposed to be NO and NO2 via the direct dissociation from NO2? and the rapid reaction of OH and NO2?, respectively. Coupled with the theoretical calculations of the absolute energies and harmonic wavenumbers of relevant species using B3LYP density functional theory with the C-PCM model to account for the medium effect of H2O, a transient band at 1860?2030 cm?1 could be attributed to dissolved N2O3 isomers that could be quickly generated from NO + NO2. On the basis of the predicted thermodynamics, the reactions of alcohols with N2O3 were less thermodynamically favorable than that of water, resulting in a slightly decelerated depletion rate of N2O3 in alcohol-containing aqueous solution. Comparing the transient population of N2O3 in the absence and presence of CH3OH or C2H5OH, the upper-bound bimolecular rate coefficient of NO or NO2 with alcohols is reported as 7.3 × 103 M?1 s?1 for the first time. The spectroscopic and kinetic evidence of the reactivity of alcohols with NO, NO2, and N2O3 are provided to augment the roles of alcohols and NxOy in solution or in aqueous aerosol photochemistry.
关键词： Alcohols,Kinetics,Nitrite,Infrared spectroscopy,Aqueous solution,Photolysis
更新于2025-09-23 15:19:57
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Microwave discharge electrodeless mercury lamp (Hg-MDEL): an energetic, mechanistic and kinetic approach to the degradation of Prozac?
摘要： A photochemical reactor composed of an Hg-MDEL was applied in photodegradation studies of fluoxetine (Prozac?). The reactor exhibited to be an efficient hydroxyl radical generation system, since constant of formation of OH? formation is optimized through the adjustment of this parameter. An increase in the initial hydroxycoumarin (4HC) and 7-hydroxycoumarin (7HC) solutions resulted in the kinetics constant value, the mean kinetic constant was k = 10.64 ± 1.25 min -1 and R 2 = 0.943 ± 0.131. The Prozac? photodegradation studies showed that the application of the pseudo-first-order applied for degradation of Prozac?, the study of variation of the microwave power allowed a concentration of Prozac from 33 to 134 μmol L-1 resulted in a 21% decrease in the kinetic significant increase in the rate of degradation of the Prozac?, indicating that the hydroxyl radical the OH? quantification studies conducted with coumarin (COU), 4- kOH = 3.14 ± 0.18 min-1. When the Hg-MDEL reactor was 100% for its highest concentration (134 μmol L-1) at the time of 0.75 min. As for the solution of Prozac? 101 μmol L-1, the energy consumption was 6 kWh g-1, achieving a removal of 99%. formation of hydroxyl radicals, a high degradation rate of organic compounds (Prozac?, COU influence exerted by the transformation products. In general, the total removal of Prozac? was kinetics should be limited to the time of up to 0.50 min for the respective system, due to the Finally, the photochemical system presented in this work demonstrates a high efficiency in the and 7HC) and low energy consumption.
关键词： hydroxyl radical,direct photolysis,fluoxetine,pharmaceuticals,and kinetics,degradation mechanism
更新于2025-09-19 17:15:36
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Photochemical study of a cyanobacterial chloride-ion pumping rhodopsin
摘要： Mastigocladopsis repens halorhodopsin (MrHR) is a Cl?-pumping rhodopsin that belongs to a distinct cluster far from other Cl? pumps. We investigated its pumping function by analyzing its photocycle and the effect of amino acid replacements. MrHR can bind I? but cannot transport it. I?-bound MrHR undergoes a photocycle but lacks the intermediates after L, suggesting that, in the Cl?-pumping photocycle, Cl? moves to the cytoplasmic (CP) channel during L decay. A photocycle similar to that of the I?-bound form was also observed for a mutant of the Asp200 residue, which is superconserved and assumed to be deprotonated in most microbial rhodopsins. This residue is probably close to the Cl?-binding site and the protonated Schiff base, in which a chromophore retinal binds to a specific Lys residue. However, the D200N mutation affected neither the Cl?-binding affinity nor the absorption spectrum, but completely eliminated the Cl?-pumping function. Thus, the Asp200 residue probably protonates in the dark state but deprotonates during the photocycle. Indeed, a H? release was detected for photolyzed MrHR by using an indium-tin oxide electrode, which acts as a good time-resolved pH sensor. This H? release disappeared in the I?-bound form and in the D200N mutant. Thus, Asp200 residue probably deprotonates during L decay and then drives the Cl? movement to the CP channel.
关键词： Flash photolysis,Microbial rhodopsin,Photocycle,Halorhodopsin,Light-driven chloride pump
更新于2025-09-19 17:15:36
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Time-resolved laser-flash photolysis Faraday rotation spectrometer: a new tool for total OH reactivity measurement and free radical kinetics research
摘要： The total OH reactivity (k’OH) is an important parameter for quantitative assessment of the atmospheric oxidation capacity. Although laboratory measurement of k’OH has been achieved 20 years ago, the instruments required are often costly and complex. Long-term atmospheric observations remain challenging and elusive. In this work, a novel instrument combining laser-flash photolysis with a mid-infrared Faraday rotation spectrometer (LFP-FRS) has been developed for the measurement of k’OH and for studying gas phase free radical kinetics. The reactor is composed of a Herriott-type optical multipass cell, and OH radicals were generated by flash photolysis of ozone with a 266 nm pulsed Nd:YAG laser. The decay of the OH signal was directly measured with a time-resolved FRS spectrometer at 2.8 μm. The overlapping pathlength between the pump beam and probe beam was 25 m. High performance was achieved by subtracting the signals before and after flash photolysis to eliminate interferences caused by H2O absorption and background drift. The optimum precisions (1σ) of OH concentration and k’OH measurement were 4×106 molecule cm-3 and 0.09 s-1 over data acquisition times of 56 s and 112 s, respectively. The performance of the system was evaluated by the reaction of OH with CO and NO. The measured rate coefficients (kOH+CO and kOH+NO) were in good agreement with values reported in the literature. The developed LFP-FRS provides a new, high precision, and highly selective tool for atmospheric chemistry research of OH radicals and other transient paramagnetic free radicals such as HO2 radicals.
关键词： atmospheric oxidation capacity,total OH reactivity,laser-flash photolysis,free radical kinetics,Faraday rotation spectrometer
更新于2025-09-19 17:13:59
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Oral mucosal irritation potential of antimicrobial chemotherapy involving hydrogen peroxide photolysis with high-power laser irradiation for the treatment of periodontitis
摘要： In the present study, we assessed the oral mucosal irritation potential of antimicrobial chemotherapy involving hydrogen peroxide (H2O2) photolysis with a 405-nm laser device at an output power of ≥100 mW in hamsters. Twenty-four cheek pouches from 12 male Syrian hamsters received 7-min treatment with pure water (PW), 3% H2O2, laser irradiation of PW at 100 mW, laser irradiation of 3% H2O2 at 100 mW, laser irradiation of PW at 200 mW, or laser irradiation of 3% H2O2 at 200 mW (n = 4 each). The diameter of the irradiation area was set at 3 mm; accordingly, the calculated irradiances (optical power densities) of the 100- and 200-mW laser lights were approximately 1400 and 2800 mW/cm2, respectively. In addition, 12 cheek pouches from six animals received laser irradiation of 3% H2O2 at 100 mW for 1, 3, or 5 min (n = 4 each). Each treatment was repeated three times at 1-h intervals. Macroscopic and histological changes were evaluated 24 h after the last treatment. In addition, in vitro bactericidal activity of the treatment against periodontal pathogens was evaluated. We found that 405-nm laser irradiation of 3% H2O2 caused moderate to severe oral mucosal irritation when performed at powers of 100 and 200 mW for ≥3 min, while the same treatment performed at 100 mW for 1 min resulted in mild irritation. Moreover, 1-min H2O2 photolysis at 100 mW caused a >4-log decrease in viable bacterial counts. These findings suggest that 1-min H2O2 photolysis, which can effectively kill periodontal pathogens, may be acceptable when a 405-nm laser device is used at 100 mW. However, use of the laser at a lower power would be preferable for the prevention of unnecessary oral mucosal irritation.
关键词： hydroxyl radicals,photolysis,periodontitis,oral mucosal irritation,laser irradiation,antimicrobial chemotherapy,hydrogen peroxide
更新于2025-09-16 10:30:52
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Degradation of acetaminophen in aqueous solution by UV and UV-activated sludge processes
摘要： Acetaminophen (N-acetyl-p-aminophenol, APAP) is one of the most common antipyretic analgesics used to treat common ailments throughout the world. Recently, APAP has been frequently detected in wastewater effluent and groundwater, resulting in potential risks to the environment. Current methods for eliminating APAP are complicated and cost-prohibitive. This study examined APAP degradation by ultraviolet-C (UV-C) and UV-C irradiation combined with activated sludge (UV/AS) to evaluate potential applications in wastewater treatment. The results of this study indicate that UV-C irradiation reached an APAP degradation efficiency of more than 52% and a degradation rate of 0.0012–0.0013 min?1 during 720 min of exposure, while the initial APAP concentration exhibited only a nominal effect on the degradation rate. However, the UV/AS treatment demonstrated an APAP degradation rate that was 9.6 times the rate of the UV-C-only treatment, with a degradation efficiency of 99% over the same UV irradiation period. The results further indicated that APAP photolysis efficiency was more effective when applied to sterilized AS than when applied to unsterilized AS. Finally, excessive dosage of both AS and humic acid inhibited APAP photolysis efficiency.
关键词： acetaminophen,photolysis,ultraviolet/activated sludge,ultraviolet-C,pharmaceuticals and personal care products
更新于2025-09-11 14:15:04
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Ciprofloxacin degradation in UV/chlorine advanced oxidation process: Influencing factors, mechanisms and degradation pathways
摘要： Ciprofloxacin (CIP) is a widely used third generation fluoroquinolone antibiotics, and has been often detected in wastewater treatment plants. Finding an effective way to remove them from wastewater is of great concern. Ultraviolet (UV)/chlorine advanced oxidation process (AOP) has many advantages in micropollutant removal. In this study, CIP degradation in UV/chlorine process was investigated. Only 41.2% of CIP was degraded by UV photolysis and 30.5% by dark chlorination in 30 min, while 98.5% of CIP was degraded by UV/chlorine process in 9 min. HCO3- had markedly inhibition, NO3- and SO42- had slight inhibition, and Cl- had a marginal inhibition on the CIP degradation in UV/chlorine system. The degradation of CIP in UV/chlorine process was mainly attributed to the attack of reactive species. The relative contributions of hydrated electrons (eaq-), hydroxyl radicals (HO.), chlorine atoms (Cl.), and UV photolysis were investigated. Under neutral condition in aqueous solution, CIP degradation had highest pseudo first-order reaction rate constants, in which eaq- followed by Cl., HO., and UV photolysis. The intermediates and byproducts were identified and the degradation pathway was proposed. The total organic chlorine (TOCl) and biotoxicity were further assessed. CIP and natural organic matters (NOMs) were removed efficiently in real water. UV/chlorine showed the potential for the wastewater treatment containing CIP.
关键词： advance oxidation process,UV/chlorine process,UV photolysis,reactive species,wastewater,Ciprofloxacin
更新于2025-09-10 09:29:36
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Photochemical Degradation of the Antimicrobial Sulfamethoxazole upon Solar Light Excitation: Kinetics and Elucidation of Byproducts Using LC/ ESI+/MS2 Technique
摘要： The fate of the antimicrobial compounds in the environment is of great interest since their presence in the aquatic systems has raised environmental problems. More and more chemicals of this class are treated as emerging contaminants. The degradation of these compounds may result in the formation of a wide array of metabolites which can be more toxic than the parent substrate. Therefore, precise elucidation of all possible transformation products as well as a thorough study of their physico-chemical and biological properties is of great importance. The present work deals with the study of the photochemical behavior of sulfamethoxazole from the kinetic aspect as well as the elucidation of the products arising from the solar irradiation of the antimicrobial sulfamethoxazole in the aqueous solutions. HPLC/MS and HPLC/MS/MS with accurate mass measurements were used for this purpose.
关键词： Photolysis,Antimicrobial,Sulfamethoxazole,HPLC/MS
更新于2025-09-10 09:29:36
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A Second-Generation Chameleon N-Heterocyclic Carbene–Borane Coinitiator for the Visible-Light Oxygen-Resistant Photopolymerization of Both Organic and Water-Compatible Resins
摘要： N-Heterocyclic carbene?boranes (NHC-boranes, NHCBs) were recently described as efficient coinitiators for the visible light photopolymerization of hydroxyethyl methacrylate (HEMA) in the presence of water. In this work, a new, more water-soluble, NHC-borane—2,4-dimethyl-1,2,4,5-tetrazol-3-ylidene borane—has been synthesized, and its efficiency in three-component systems (dye (Acridine Orange), disulfide, and NHC-borane coinitiators) for the polymerization of methacrylate resins under visible light under air has been studied. In fluid resins this new photoinitiating system (PIS) gives better results than the one previously studied. More importantly, this system is competitive with the widely used type II system—camphorquinone/4-(dimethylamino)benzonitrile (DMABN)—for the polymerization of methacrylate resins but better for the photopolymerization of poly(2-hydroxyethyl methacrylate) leading to hydrogels, where the former PIS fails. The excellent ability of the NHC-boranes, and especially the new one, to be used as photopolymerization coinitiators has been analyzed by laser flash photolysis (LFP). The rate constants for elementary reactions of the three boranes and their derived NHC-boryl radicals obtained by LFP correlated well with the molecular modeling data and show that the key for the observed reactivity is the ability of the tetrazolydinyl NHC-borane to repair the peroxyl radicals formed by the reactions of the macroradicals with oxygen.
关键词： laser flash photolysis,methacrylate resins,N-Heterocyclic carbene?boranes,hydrogels,visible light photopolymerization
更新于2025-09-09 09:28:46