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ABSTRACT Photosensitizers and pigments in raw meat such as porphyrins, riboflavin, and myoglobin after incorporation with light beam prompt the generation of singlet oxygen (1O2) from triplet oxygen (3O2) and cause oxidative rancidity of meat products. In this study, the results of photooxidation reactions of sheep erythrocyte (red blood cell) model as a model rich in hemoglobin and phospholipids bilayer, and oleic acid model were obtained by 1H NMR spectroscopy, TBARS assay, and iodometric titration. In both models, the rate of lipid photooxidation in the presence of hydroalcoholic extracts of Turmeric (Curcuma longa L.) and Cumin (Cuminum cyminum L.) as natural antioxidants, Butyl hydroxytoluene (BHT) as a synthetic antioxidant, and sodium azide (NaN3) as a well‐known 1O2 scavenger were decreased in the order of NaN3 > Turmeric > Cumin > BHT. It was proven that during the photooxidation process, there is a direct association between the amount of flavonoid compounds and 1O2 scavenging. [ABSTRACT FROM AUTHOR]

Healthcare‐associated infections remain a significant health concern, particularly with the emergence of antibiotic resistance. While these antibiotics have saved countless lives, their overuse reduces their efficacy promoting the emergence of multidrug‐resistant (MDR) bacteria. This prompts researchers to explore new alternatives for treating bacteria proliferation. In this context, antibacterial photodynamic therapy (aPDT) has emerged as a promising approach for treating localized infections. It utilizes reactive oxygen species (ROS) as oxidative stress agents, thereby minimizing the risk of developing MDR. The success of aPDT significantly hinges on the careful selection of photosensitizers (PSs) and polymer matrices for the synthesis of polymer‐based photoactive materials. Various light‐absorbing PSs are therefore designed for enhancing ROS production and antimicrobial efficacy. By incorporating PSs into polymer matrices, these materials can harness the light power to generate ROS, destroying bacterial cells upon irradiation. This review aims to provide a comprehensive overview of advancements in this field, specifically focusing on the use of polymer‐based materials. The mechanism of the four main ROS generated in aPDT, the methods used for their detection, and their mode of action against bacteria has been outlined. The recent improvement in polymer‐based aPDT materials and their antibacterial efficacy have been also addressed. [ABSTRACT FROM AUTHOR]

Precious metals are valuable materials for the chemical industry, but they are scarce and pose a risk of supply disruption. Recycling precious metals from waste is a promising strategy, here we tactfully utilize light irradiation as an environmental‐friendly and energy‐saving adjunctive strategy to promote the reduction of precious metal ions, thereby improving the adsorption capacity and kinetics. A newly light‐sensitive covalent organic framework (PP‐COF) was synthesized to illustrate the effectiveness and feasibility of this light auxiliary strategy. The equilibrium adsorption capacities of PP‐COF with light irradiation towards gold, platinum, and silver ions are 4729, 573, and 519 mg g−1, which are 3.3, 1.9, and 1.2 times the adsorption capacities under dark condition. Significantly, a filtration column with PP‐COF can recover more than 99.8 % of the gold ions in the simulated e‐waste leachates with light irradiation, and 1 gram of PP‐COF can recover gold from up to 0.15 tonne of e‐waste leachates. Interestingly, the captured precious metals by PP‐COF with light irradiation mainly exist in the micron‐sized particles, which can be easily separated by extraction. We believe this work can contribute to precious metal recovery and circular economy for recycling resources. [ABSTRACT FROM AUTHOR]

In this study, porous polymers with nitrogen heterocyclic core structures are synthesized through the condensation of enaminonitrile and terephthalaldehyde monomers. These polymers are used as a platform to store bioactive nitric oxide (NO) and control its release. NO loading is achieved by nitrosating the polymers with acidified nitrite, a process that also imparts photoresponsivity to the polymers. Polymer composition and porosity affect NO storage and release. It is observed that under UV light at 365 nm in a PBS solution, the polymers (NO@DHP‐POP) can release NO in a manner fully controlled by UV lighting. Under experimental conditions, these porous polymers release NO at a rate of ≈10.0–50.0 µmol g−1 over 60 min. These findings demonstrate the potential of these polymers for integrating NO delivery into phototherapy applications. [ABSTRACT FROM AUTHOR]

Photo‐induced reversible complexation‐mediated polymerization (RCMP) is a green and economical method to prepare polymers with precise molecular weights, narrow molecular weight distributions and functionally active chain ends. Covalent organic frameworks (COFs) are a promising heterogeneous photocatalyst for mediating RCMP due to their adjustable structure, band gap, and porosity. In this work, 1,3,5‐triformylphloroglucinol (Tp) and p‐azoaniline (Azo) were selected to construct 2D β‐ketoenamine linked Tp‐Azo‐COF as a heterogeneous photocatalyst to trigger RCMP under white light irradiation. A series of polymers with controllable molecular weight and narrow molecular weight distribution were successfully prepared by using Tp‐Azo‐COF as photocatalysis. On/off light experiments confirmed the good spatiotemporal control feature, and chain expansion experiments demonstrated the high "activity" of polymer chain ends. Furthermore, the mechanistic research elucidated that electron transfer between Tp‐Azo‐COF and initiator occurred, allowing the formation of reactive radicals to mediate RCMP. Density functional theory calculations revealed that the coordination of iodine on the initiator to catalyst obviously reduced the bond dissociation energy, leading to enhance in the polymerization rate. This work provides a platform for constructing heterogeneous photocatalysts with more efficient and stable to mediate RCMP. [ABSTRACT FROM AUTHOR]

This study investigates the incorporation of active secondary amine moieties into the polymer backbone by co‐polymerizing 2,4,6‐tris(chloromethyl)‐mesitylene with three diamines, namely 1,4‐diaminobutane, m‐phenylenediamine, and p‐phenylenediamine. This process results in the stabilization of the amine moieties and the subsequently introduced nitroso groups. Charging bioactive nitric oxide (NO) into the polymers is accomplished by converting the amine moieties into N‐nitroso groups. The ability of the polymers to store and release NO depends on their structures, particularly the amount of incorporated active secondary amines. With grafting photosensitive N‐nitroso groups into the polymers, the derived NO@polymers exhibit photoresponsivity. NO release is completely regulated by adjusting UV light irradiation. These resulting polymeric NO donors demonstrate remarkable bactericidal and bacteriostatic activity, effectively eradicating E. coli bacteria and inhibiting their growth. The findings from this study hold promising implications for combining NO delivery with phototherapy in various medical applications. [ABSTRACT FROM AUTHOR]

Thanks to supramolecular interactions of macrocyclic compounds with their guest ions or molecules, macrocycles have found wide applications in molecular and chiral recognition, separation, transportation, molecular machines, and so on. Photoswitchable macrocycles are especially appealing and attracting more and more interest because the embedded molecular photoswitch enables dynamic control of molecular shape, conformation, and different properties by light, a non‐invasive, remote and highly tunable stimulus. With available photochromic compounds, various photoswitchable macrocycles have been developed. In this review paper, we describe the recently reported photoswitchable macrocyclic compounds, with a focus on the control of the macrocyclic structure, dynamic, photo or thermal isomerization, as well as their applications on encapsulation and release of ionic or aromatic species, on the reversible modulation of chemical, biological, electronic, fluorescent and chiroptical properties by light. [ABSTRACT FROM AUTHOR]

Small gold nanoparticles (GNPs) show special catalytic activity for hydrogen (H2) dissociation reaction, which is essential and important in understanding the hydrogen oxidation reaction in hydrogen energy source. To insight on catalytic properties of GNPs, we simulated H2 dissociation paths on neutral gold clusters (GCs) Aun (n = 1–6) and positively charged GCs Aun+ (n = 3–5), which are possible active sites on GNPs. The calculated results show that H2 dissociation on GCs follows a homolytic cleavage reaction process. Light irradiation and water environment are considered for H2 dissociation on Aunδ+ (n = 3–5, δ = 0 and +1) clusters. The calculated results show that when the incident light has a low energy close to the surface plasmon resonance (SPR) region of GNPs, the light can effectively reduce the H2 dissociation barrier, and an oxidation dissociation process is found for the water‐assisted H2 dissociation reaction. [ABSTRACT FROM AUTHOR]

It is highly desired to achieve controllable product selectivity in CO2 hydrogenation. Herein, we report light‐induced switching of reaction pathways of CO2 hydrogenation towards CH3OH production over actomically dispersed Co decorated Pt@UiO‐66‐NH2. CO, being the main product in the reverse water gas shift (RWGS) pathway under thermocatalysis condition, is switched to CH3OH via the formate pathway with the assistance of light irradiation. Impressively, the space‐time yield of CH3OH in photo‐assisted thermocatalysis (1916.3 μmol gcat−1 h−1) is about 7.8 times higher than that without light at 240 °C and 1.5 MPa. Mechanism investigation indicates that upon light irradiation, excited UiO‐66‐NH2 can transfer electrons to Pt nanoparticles and Co sites, which can efficiently catalyze the critical elementary steps (i.e. CO2‐to‐*HCOO conversion), thus suppressing the RWGS pathway to achieve a high CH3OH selectivity. [ABSTRACT FROM AUTHOR]

The impact of different light irradiation was studied on photocatalytic degradation of 2‐chlorophenol (2‐CP) using mesoporous titania nanoparticles (MTNs) prepared by microwave‐assisted methods. The photoactivity of MTNs was also compared with pretreated commercial TiO2 and Degussa P25 (P25). The reactions were conducted for 2.5 hr under UV‐A, UV‐C, sunlight, and visible light using a batch reactor. The catalysts were characterized by X‐ray powder diffractometer, UV–Vis diffuse reflectance spectroscopy, photoluminescence, Brunauer–Emmett–Teller method, field‐emission scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The characterization results confirmed that MTN consisted a composition of 21% rutile phase and 79% anatase phase with Ti3+ site defects (TSDs) and oxygen vacancies (OVs) in their structures because of their anionic surfactant nature, microwave heating, and high calcination temperature during the catalyst preparation. Besides, the photoactivity of MTN upon degradation of 2‐CP under sunlight has exhibited the best performance with 100% degradation followed by UV‐A, visible light, and UV‐C with degradation of 96, 52, and 39%, respectively. MTNs showed a remarkable performance due to their mixed‐phase crystalline structures as well as the formation of TSDs and OVs, which improved the charge migration, lowered the band gap energy, and reduced the rate of electron–hole recombination, thus succeeded to be activated under a wide range of light responses. [ABSTRACT FROM AUTHOR]

The present study demonstrates the effect of light irradiation on the esterification of oleic acid catalyzed by immobilized Pseudomonas cepacia lipase. The reaction rates of all the experiments under light irradiation were found to be higher than dark conditions. The kinetics of reactions supported the Ping‐Pong Bi‐Bi mechanism with dead end inhibition by both the alcohol and acid substrates. Moreover, circular dichroism (CD) spectroscopy was used to analyze the effect of light on lipase enzyme. The CD spectroscopic studies confirmed that the conformational changes in the secondary structure of the lipase enzyme increased the reaction rate of light‐illuminated experiments, which might have opened up the active sites of enzymes and thus, resulted in higher reaction rates compared to dark reactions. These results have successfully demonstrated that the light illumination positively influenced the rate of P. cepacia enzyme‐catalyzed esterification reactions. [ABSTRACT FROM AUTHOR]

Abstract: A large and reversible upconversion (UC) luminescence modulation has been found in the Na0.498Bi0.498TiO3:0.002Er (NBT:0.002Er) based on the photochromic reaction. The dependence of luminescence modulation of the ceramics on the wavelength of irradiation light and sintering temperature was investigated. It was found that the optimized sintering temperature and irradiation wavelength were 1130°C and 405 nm, respectively. The highest ΔRt (defined as: ΔRt = (R0 – Rt)/R0×100(%), where R0 and Rt are the initial emission intensity and that after different irradiation time, respectively) value of 44.9% was obtained for the ceramics sintered at 1130°C after irradiation at 405 nm. More importantly, for the poled ceramics, ΔRt value was promoted to a high value of 75.5%, which was 168% of that of the unpoled ones. The mechanism of luminescence modulation and its enhancement via electric field poling were discussed. This study demonstrated that electric field poling was an effective strategy to enhance the PC reaction in the NBT ceramics. [ABSTRACT FROM AUTHOR]

Abstract: A light‐triggered shape change of supramolecular nanostructures is achieved through electrostatically self‐assembly of linear polyelectrolytes and oppositely charged dyes in aqueous solution: Upon UV‐irradiation, 1‐µm‐long, flexible cylinders with a cross‐section of 10 nm convert into ellipsoids of 400 nm × 40 nm. The nano‐object shape is encoded in the molecular dye structure. [ABSTRACT FROM AUTHOR]

Photocatalytic technology utilizing abundant solar light holds great promise to tackle many challenging environmental and energy issues. In recent years, various types of photocatalysts have been developed that are active for environmental purification and hydrogen production. Papers reporting preparation, characterization and photocatalytic testing of binary, ternary and quaternary compounds have been reviewed. The present review focuses on photocatalyst materials which adopt a defect pyrochlore structure. Starting with a brief introduction to semiconductor-based photocatalysts for environmental clean-up and hydrogen generation from water splitting, the development of high-efficiency UV and visible light driven photocatalysts belonging to the defect pyrochlore family is reviewed. The review covers all the defect pyrochlore photocatalysts studied so far, and provides guidance to researchers in this area for further investigation of these materials. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The results of investigation of slow surface dynamics (easy axis gliding), induced by secondary illumination of photoaligned substrates with linearly polarized UV or blue light in the presence of electric (magnetic) fields, are presented for the first time. The initial surface orientation of nematic liquid crystal (NLC) was provided, in accordance with the standard photoalignment technique, via preliminary UV treatment of the glass substrates coated by sulfonic azo-dye SD1 film. The experiments fulfilled for the two geometries, A and B, corresponding to the normal (A) and parallel (B) orientation of fields relatively to liquid crystal (LC) layer, revealed different effects induced by electric (magnetic) fields. For geometry A, strong electric field applied, in combination with a linearly polarized blue light, to the planar layer in a sandwich-like LC cell with two photoaligned substrates results in simultaneous reorientation of easy axis on both substrates. It demonstrates the possibility of an azimuthal rotation of monodomain planar samples of LCs. For geometry B, usage of 'in-plane' electric (magnetic) fields in the cell, composed of photoaligned and rubbed substrates, speeds up reorientation process of NLC easy axis respectively to pure light-induced reorientation. It provides electric control of operating times in previously proposed optical rewritable technology. [ABSTRACT FROM AUTHOR]

Epitaxial BiFeO3 (BFO) film is deposited on the SrRuO3-buffered (001) SrTiO3 substrate by magnetron sputtering. Here, we report the observation of photoinduced changes in polarization-electric hysteresis loop and photovoltaic effect of BFO film when it is illuminated by violet light of 404 nm. The remanent polarization is 57.4 and 65.8 µC/cm2 in the dark and in violet light, respectively, which is explained based on the reorientation of the ferroelectric domains. The open-circuit voltage for photovoltaic effect is 0.28 V. The short-circuit current density displays an almost 100 times enhancement, i.e. from 0.09 µA/cm2 in the dark to 9 µA/cm2 in violet light. [ABSTRACT FROM AUTHOR]

ABSTRACT Microalgae cultures show wide range of pH depending on the availability of light and CO2 for their strain specific photosynthesis. Thus, the modulation of light irradiation and CO2 supply can be applied for the pH control of microalgae cultures. The optimal pH of Ettlia sp. YC001, for phototrophic growth and auto-flocculation was investigated by controlling light irradiation and 10% CO2 supply. Ettlia sp. YC001 showed the highest biomass productivity, 96.7 mg L−1 d−1, at pH 8.5. The flocculating activity of Ettlia sp. YC001 showed a sigmoid pattern with pH increase and was above 70% at pH 10.5. Based on these differentiated optimal pH regimes for the growth and flocculation, an integrated process consisting of cultivation and settling vessels was proposed. The integrated process demonstrated that high flocculation activity of Ettlia sp. YC001 could be achieved in the settling vessel with various hydraulic retention times by only irradiation of light to maintain high pH while maintaining the optimal growth in cultivation vessel with the light irradiation and CO2 supply at pH 8.5. Thus, the proposed strategy for pH control would provide a simple, cost-effective, and flexible design and operation for microalgae cultivation-harvest systems. Biotechnol. Bioeng. 2015;112: 288-296. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The aim of this work is to examine the effect of irradiation on the structure, the electrical resistivity and electromagnetic radiation (EMR) shielding (frequency range of f = 25.5-37.5 GHz) of nanocarbon-epoxy composites (CMs). The graphite nanoplatelets (GNPs) and multi-walled carbon nanotubes (MWCNTs) are used as fillers in epoxy polymer matrix (epoxy resin ED20). Nanocarbon filler content is 1-2.2 vol.%. Polymer-nanocarbon CMs were irradiated by different methods: UV irradiation for 51 h, СuKα X-ray radiation ( U = 30 kV, i = 20 mA) for 1 h, electron irradiation (1.8 MeV, the absorbed dose is 1 MGr), ions H+ (1.5 MeV, 5 × 1016), C+ (3 MeV, 4 × 1016). It was shown, that the different types of radiation provide different influence both on the value and character of the temperature dependence of resistivity. The most significant change of resistivity was observed for the specimen irradiated by UV - resistivity decreases almost by three orders (by 806 times), the temperature dependence of resistivity being weakened. For specimens irradiated by UV and X-ray we also have observed the increase of shielding efficiency as compared with initial CM, while the irradiation of specimen by electrons leads to a decrease of shielding efficiency SET. According to Raman investigation results, the irradiation by H+ ions of CM 2 wt.% MWCNTs-ED20 with intensity 1.5 MeV leads to significant destroying of nanotube structure and formation of homogeneous amorphous material. [ABSTRACT FROM AUTHOR]

A new fluorescent nanoparticle ( PIOT-HA) is synthesized with cationic polyester ( PIOT) and anionic hyaluronic acid (HA) by electrostatic interactions in an aqueous solution. The nanoparticles (NPs) are degradable upon treatments with alkali or hyaluronidase, which exhibits better biological safety and potential application in vitro and in vivo. Through specific interactions between the HA locating on the surfaces of PIOT-HA NPs and the CD44 protein over-expressed on the MDA-MB-231 cancer cell line, PIOT-HA NPs could selectively image the cancer cells. Upon white light irradiation, the PIOT-HA NPs can sensitize oxygen to generate reactive oxygen species (ROS) that inactivate the neighboring CD44 protein, which inhibits the migration of MDA-MB-231 cancer cells. [ABSTRACT FROM AUTHOR]

Significance A novel approach for ultra-deep desulfurization of diesel fuel was proposed, in which the original fuel was treated by light irradiation before adsorptive desulfurization (ADS) over the TiO2-CeO2/MCM-48 adsorbent under ambient conditions. A superior capacity of 95 cm3-fuel/g-adsorbent (32 times higher than that of the original fuel) was achieved. The promoting effect of light irradiation was likely through in situ peroxides generation in fuel under visible light/sunlight, which may oxidize organosulfur to form strongly adsorbed sulfones over the adsorbent. [ABSTRACT FROM AUTHOR]

As a powerful tool of cell screening and cell purification, we developed a novel method to kill adherent cells as cultured on a substrate by micro-projection of incoherent visible light. To kill the cells by the mild light irradiated by electrically controllable micro-projection systems currently available, we introduced the assist of the photo-responsive culture substrates functionalized with a photo-acid-generating polymer. In clear contrast to the existing laser-based methods requiring point scanning, areal micro-prjection of blue light with the wavelength 436 nm killed many CHO-K1 cells at a time in the irradiated area on the substrate. The effect of the photo-generated acid was so confined that selective killing of targeted cells was achieved without critical damage to the neighboring cells. Further, we demonstrated the photo-selective killing of the adherent cells after preliminarily patterning through the photo-induced removal of cell adhesion-inhibiting polymer. Biotechnol. Bioeng. 2013; 110: 348-352. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The unicellular eukaryote, Blepharisma japonicum, is a light-sensitive ciliated protozoa. It possesses a photoreceptor pigment called blepharismin that plays critical roles in defensive behavior against predators and step-up photophobic response. In addition, the pigment generates reactive oxygen species such as singlet oxygen and hydroxyl radicals which contribute to photodynamic action. Previous studies reported that intense light (>300Wm−2) induced rapid photodynamic killing (necrosis) characterized by cell swelling and plasma efflux, while moderate light (3–30Wm−2) only induced pigment extrusion and photooxidation. We have found that moderate light (5Wm−2) induced apoptosis-like cell death. Microscopically it was found that >3h of moderate light irradiation induced macronuclear condensation and plasma efflux without cell swelling. Single cell gel electrophoresis assay showed that DNA fragmentation occurred between 1 and 3h of irradiation, and the condensed macronuclei contained quite fragmented DNA. Macronuclear DNA extracted from light-irradiated cells contained DNA fragments of 180–200 and 360–400bp, which were seen as apoptosis ladders. [Copyright &y& Elsevier]