Photostability Test Research Articles

Green Fluorescent Diamino‐Terephthalonitriles with Reactive Terminal Groups Towards Synthesis of Value‐Added Fluorophores

AbstractWe report synthesis of a library of diamino‐terephthalonitrile based single‐benzene fluorophores (SBFs). These SBFs contain a reactive terminal linker group. They open up the possibility of marrying their excellent fluorescent property with various biogenic units, leading to value‐added SBFs. The solvatofluorochromism behavior of these newly synthesized SBFs was also studied. The emission enhances and blue‐shifts in case of non‐polar solvents and vice versa in the polar solvents, implying the environmental sensitivity of these fluorophores. Photostability test was also done to test for the stability of the emission of these fluorophores with time and the fluorophores were found to be stable. We also observed time‐dependent fluorescence enhancement of one of our SBFs in presence of reactive biogenic amines. Overall, the generation of these novel molecules opens up new opportunities towards bioconjugated fluorophores.

A specific chiral HPLC method for lifitegrast and determination of enantiomeric impurity in drug substance, ophthalmic product and stressed samples

Lifitegrast is a lymphocyte function-associated antigen-1 (LFA-1) antagonist used to treat the indications and symptoms associated with dry eye disease (DED), one of the most common ocular surface diseases. Lifitegrast has a chiral center, and the S-enantiomer (S-Lif) is responsible for the therapeutic effects, while the R-enantiomer (R-Lif) lacks efficacy in the treatment of DED. Lifitegrast ophthalmic solution containing 5% lifitegrast was approved by the United States Food and Drug Administration (FDA) in July 2016 for the treatment of DED in patients 17 years of age and older. The objective of this study was to develop a chiral HPLC method for the determination of the enantiomeric impurity of lifitegrast in the drug substance and in the ophthalmic product. In addition, we aimed to investigate the effect of stress and stability conditions on the enantiomeric purity of lifitegrast in both drug substance and ophthalmic solution. During the method development studies, four known lifitegrast impurities (Lif. Imp. A-D) and stressed lifitegrast samples were injected to ensure the specificity of the developed method. The enantiomers of lifitegrast are well separated with a resolution of higher than 4.0. They are also well separated from the peaks of the diluent, impurities, and the placebo used to prepare the ophthalmic solution without interference in 20 min. Chiral separation was achieved using a Chiralpak AD-H column (250 × 4.6 mm, 5.0 μm) at 40 °C with a mobile phase consisting of a mixture of n-hexane, 2-propanol, and formic acid (500:500:2, v/v/v) at a flow rate of 1.0 mL/min and a detection wavelength of 260 nm. Methanol was used as the diluent, and the drug substance solution was found to be stable for 48 h at 15 °C. The optimized chiral HPLC method for lifitegrast was validated according to ICH Q2, and the calibration curves showed excellent linearity for R-Lif (0.0369 – 1.816 µg/mL). This is the first stability-indicating, specific / selective, sensitive, linear, precise, accurate, and robust chiral HPLC method for the determination of R-Lif in S-Lif. The amount of enantiomeric impurity R-Lif in S-Lif increased under all stress and photostability test conditions without exceeding the acceptable impurity limit, with the most significant increase observed at elevated temperatures (105 °C) for both the drug substance in powder form and the ophthalmic drug solution.

Well-structured V2C MXenes coupled g-C3N4 2D/2D nanohybrids for proficient charge separation with the role of triethanolamine (TEOA) as a protective barrier of g-C3N4 for stimulating photocatalytic H2 production

Vanadium-carbide (V2C) MXenes have received scientific attention for their thinner structure, multiple oxidation states, and excellent conductivity, which can effectively serve as electron-sinking sites to suppress the backward recombination of electrons and holes. Herein, well-structured V2C/g-C3N4 nanohybrids were designed to promote photocatalytic hydrogen production. Stronger interfacial contact between 2D/2D V2C/g-C3N4 proffers 4.23-fold more H2 yield than pristine g-C3N4 with a maximal rate of 360 μmol g−1 h−1. The loading of V2C improves the light absorption capability and facilitates the charge transfer for photo-redox reaction. However, h+ accumulation fosters the degradation kinetics over consecutive cycles, which drives the homolytic cleavage of the g-C3N4 by hydroxyl radical (• OH). The tremendous decline in the photostability test over methanol-containing sacrificial reagents is consistent with the reduction of g-C3N4 functional units, corroborating the structural breaking. Employing TEOA as a hole scavenger slows the homolytic decomposition of g-C3N4, which could act as a binding ligand in protecting the g-C3N4 surface. Stronger intermolecular forces between the heterogeneous molecules with excellent scavenging activity effectively trap accumulated h+ and slow down the degradation kinetics. The findings of this work not only contribute to the scientific understanding of vanadium-based MXenes in photocatalytic hydrogen production but also lay the foundation for understanding the mechanistic structure of g-C3N4.

Photostability of vitamin C in industrialized fruit juices and isomers determination by HPLC-DAD

L-ascorbic acid (LAA) and D-isoascorbic acid (DIAA) are two of the most important antioxidants in industrialized fruit products as mixed fruit juices, fruit concentrates, and jams, in which they are added as antioxidants and as a nutrient. Despite that, LAA may undergo oxidative- and photo-degradation during storage, compromising its concentration and activities in these food products. In this work we aimed to optimize a method for the identification and quantification of LAA and DIAA by high performance liquid chromatography with diode-array detection (HPLC-DAD) using a NH2 column and a pre-heated mobile phase. A further aim was to investigate if food packing actually protects fruit juices against LAA photodegradation. For the UV photostability test, samples were UV-irradiated at 1416 μW cm−2, at 28 ± °C, and with a radiation energy above 200 W h m−2. The optimized HPLC method provided complete peak resolution of vitamin C isomers in less than nine min run-time. At the end of photostability tests with fruit juices and jellies packaged in polyethylene terephthalate and glass bottles or flasks, L-ascorbic acid was undetectable, suggesting that the packages did not provide effective protection against vitamin C photodegradation. To the best of our knowledge, vitamin C photostability in fruit products was previously unreported.

Synthesis and testing of carbon quantum dots loaded 2D Bi2MoO6 for efficient Hg0 photocatalytic removal

Carbon quantum dots (CQDs) was prepared and supported on 2D Bi2MoO6 by hydrothermal method to prepare 2D Bi2MoO6/CQDs composite photocatalyst with up-conversion luminescence (UPCL) characteristics. The properties of 2D Bi2MoO6/CQDs were characterized by a series of characterization tools. Then, 2D Bi2MoO6 and 2D Bi2MoO6/CQDs catalysts were applied to photocatalytic Hg0 removal. The experimental results show that Hg0 removal efficiency of 2D Bi2MoO6/CQDs increased from 30.5% to 80.1% under visible light and from 7.2% to 26.4% under near-infrared light compared with 2D Bi2MoO6. The photostability test shows that 2D Bi2MoO6/CQDs nanocomposites could maintain high photostability after five photoreaction cycles. UPCL test proved that CQDs had the ability to absorb infrared light and emit visible light, thus expanding the light utilization range of composite catalyst. Moreover, in N2+6%O2+12%CO2+NO atmosphere, Hg0 removal efficiency of 2D Bi2MoO6/CQDs first dropped and then raised with the increase of NO concentration due to the simultaneous reduction and oxidation of NO in the system. Finally, the ESR test shows that the modification of CQDs could not only enhance light absorption rang of photocatalyst, but also promote the transfer of photogenerated carriers on the catalyst surface, thereby enhancing the photocatalytic Hg0 removal capability of the 2D Bi2MoO6/CQDs catalyst.

Evaluation of the Physical Properties and Anti-aging Microemulgel Sunscreen Nyamplung Oil (Calophyllum inophyllum L.)

Exposure to UV rays can cause photoaging, and a photoprotective compound can be used to prevent it, as well as being used as an active ingredient in sunscreen. The potential side effects and contamination of existing sunscreens on the market call for alternatives such as natural ingredients. Nyamplung oil (Calophyllum inophyllum L.) has the potential to be used as a sunscreen gel, with a 30.46 SPF value in its formulation. However, Nyamplung oil has the disadvantage of being hydrophobic. Therefore, this study aims to formulate it in the form of a microemulsion gel as a dual-action sunscreen with anti-aging activity. The optimization of the microemulsion formula were performed using Design Expert software, with observations on droplet size, polydispersity index (PDI), and zeta potential. The sunscreen was tested for its SPF value, percent (%) erythema transmission (%Te), percent (%) pigmentation transmission (%Tp), and percent (%) residual elastase enzyme activity (%AE), to demonstrate its anti-aging activity, as well as being tested for its physical properties against the effects of storage, temperature, and photostability, and its safety in potential irritation on rabbits. The optimum micro emulsion formula had a droplet size of 172.46 nm, a PDI of 0.196, and a zeta potential of -6.36 mV. The microemulgel sunscreen met the physical requirements of gel preparations, with an SPF value of 25.73, %Te and %Tp values for sunblock protection categories, and providing 62.96% anti elastase activity at a concentration of 10%. The sunscreen was stable during storage and with the influence of temperature. However, the sunscreen indicated a decrease in SPF value by 18.19% after a photostability test.

Evaluation of Photostability of Medicines and Development of the Photostabilization of the Photosensitive Medicines

Photo-exposure has a crucial effect on both the quality and quantity of photosensitive pharmaceuticals due to the decrease of their contents or the expression of adverse effects derived from generated photoproducts. The photostability test guidelines (ICH-Q1B, Photostability testing of new drug substances and products) have been established for the photostability evaluation in the new drug application, and obtained results from these tests are required for the elucidation of the final packaging and the dosage form. However, there is no information in the interview form about the photostability of medicines that are taken out from a press through package (PTP) sheet and their dosage forms are changed for the purpose of the improvement of medication compliance of patients. It is an important issue to clarify the photostability of medicines that are crushed or suspended and determine the potential photoproducts for safe use. Herein, in this review, results of the evaluation of the photodegradability of photosensitive active pharmaceutical ingredients (APIs) and their formulations, the determination of several photoproducts generated by ultraviolet-light (UV) irradiation and the development of photostabilization strategy for them based on the addition of several photostabilizers are summarized.

Blade Coating Inverted Perovskite Solar Cells with Vacuum‐Assisted Nucleation Based on Bottom Quasi‐2D Passivation

Metal halide perovskite solar cells (PSCs) attract an enormous attention because of their high power conversion efficiency (PCE) and low fabrication cost. However, their commercialization is limited by fabricating highly efficient large‐area solar cells. Controlling the morphology and crystallization of perovskite for large‐area fabrication is difficult but important. Herein, a vacuum‐assisted approach is developed to obtain mirror‐like, pinhole‐free, highly crystalline, and uniform blade‐coated perovskite films, without the use of antisolvent and air knife. This method can be a universal approach for various perovskite compositions. Meanwhile, the phenethylammonium iodide passivation effect at the top and bottom interfaces of perovskite layer based on FTO/NiOx/perovskite/C60/BCP/Cu inverted p‐i‐n structure is systematically investigated. The optimized device fabricated by blade coating under an ambient environment exhibits the champion PCE of 20.7% and is among the top few records of blade coating inverted structure based on NiOx hole transport layer. The encapsulated device retains 97% of its maximum efficiency under open‐circuit condition after 1000 h of photostability test in an ambient environment at room temperature with a relative humidity of 40–60%. Herein, low‐cost, easy, and reproducible strategies to fabricate efficient and stable blade‐coated PSCs are demonstrated.

Compositionally engineered Cd-Mo-Se alloyed QDs toward photocatalytic H2O2 production and Cr(VI) reduction with a detailed mechanism and influencing parameters.

With the exceptional advantages of safety, greenness, and low cost, photocatalytic H2O2 generation has kindled a wonderful spark, although being severely hampered by the terrible photoinduced exciton recombination, migration, and surface decomposition. Here, employing reflux method, the Cd-Mo-Se quantum dots of varying molar ratios of Cd and Mo were synthesized using thioglycolic acid as the capping ligand to regulate their growth. This type of metal alloying promotes rapid charge migration, improves light harvesting, and reduces the rate of charge recombination. The improved optoelectronic properties and boosted activity of Cd-rich ternary CMSe-1 QDs led to the observed exceptional photocatalytic H2O2 yield of 1403.5 μmol g-1 h-1 (solar to chemical conversion efficiency, 0.27%) under visible light, outperforming the other ternary and Se-based QD photocatalysts. Additionally, CMSe-1 shows 93.6% (2 h) hazardous Cr(VI) photoreduction. The enhanced catalytic performance of CMSe-1 corresponds to effective charge carrier separation and transfer efficiency, well supported by PL, TRPL, and electrochemical measurements. Photocatalytic H2O2 production was also studied under varying experimental conditions and the scavenger test suggests a superoxide radical intermediate 2-step single electron reduction pathway. The catalyst-assisted Cr(VI) reduction is substantiated by the zero-order kinetics as well as the determination of the pHPZC value. The catalyst can be employed for a maximum of four times while retaining its activity, according to the photostability and reusability test outcomes. This research presents interesting approaches for producing ternary QDs and modified systems for efficient photocatalytic H2O2 production and Cr(VI) reduction.

Dye-sensitized solar cells based on highly catalytic CNTs/Ti3C2Tx MXenes composite counter electrode.

Establishing stable and efficient Pt-free counter electrodes (CEs) is an important challenge for dye-sensitized solar cells (DSSCs). Ti3C2Tx MXene, with its high catalytic activity and conductivity, has gained attention as a CE in DSSCs. The focus of this paper is on the preparation of Ti3C2Tx decorated carbon nanotubes (CNTs) composite electrode materials (CNTs/Ti3C2Tx), and testing their performance as CEs in DSSCs. Through a series of electrochemical tests, a CNTs/Ti3C2Tx CE exhibits good electrocatalytic activity toward iodine-based electrolytes with low charge transfer resistance, which is close to the performance of a Pt CE. The photoelectric conversion efficiency (PCE) of the CNTs/Ti3C2Tx (1.0 wt%) CE-based DSSCs reaches 5.83%, which is much higher than that of the CNTs CE (3.70%), and approximates that of the Pt CE (6.61%). We attribute the improved performance to the synergistic effect of the excellent conductivity and unique two-dimensional chemical structure of Ti3C2Tx MXene. Moreover, the photostability test of continuous light exposure shows that the CNTs/Ti3C2Tx-1.0 wt% (C/T-1.0 wt%) CE exhibits good stability to the electrolyte. Therefore, CNTs/Ti3C2Tx composites can be used as an efficient Pt-free CE for DSSCs in the future.

Near-Unity Photoluminescence Quantum Yield of Green-Emitting Graded-Alloy Core/Shell Giant Quantum Dots by z-Type Ligand Passivation for Display Applications

As-synthesized, green-emitting graded-alloy core/shell “giant” quantum dots have outstanding properties that can be utilized for different optoelectronic applications. But often, defects arise upon nonuniform growth of the shell. These surface defects affect the photoluminescence quantum yield (PLQY), lifetime, and stability of the green-emitting graded-alloy core/shell “giant” quantum dots. So, to overcome these surface traps, the graded-alloy core/shell g-QDs were passivated with z-type ligands (ZnCl2, CdCl2, and MgCl2). The change in the PLQY, lifetime, and photoluminescence emission confirmed that the z-type ligands are passivating the trap states of g-QDs by bonding with an unsaturated chalcogenide atom on the surface, and this was confirmed by X-ray photoelectron spectroscopy. All three cases (treated with ZnCl2, CdCl2, and MgCl2) showed outstanding enhancement in the photoluminescence quantum yield. Fascinatingly, the ZnCl2-treated g-QDs showed maximum enhancement in the PLQY from 62% to unity. Furthermore, the photostability test was performed under continuous UV-light irradiation for 24 h, which clearly showed superior photostability. Moreover, the temperature-dependent stability of untreated and treated g-QDs was studied from 10 to 90 °C. Furthermore, the green-emitting down-converted LED was fabricated by utilizing ZnCl2-treated g-QDs, which show great potential for display application.

Utilizing Organic Aromatic Melamine Moiety to Modify Poly(Vinyl Chloride) Chemical Structure and Micro CuO That Plays an Important Role to Enhance Its Photophysical Features

Three arms Schiff base unit based on melamine moiety was synthesized and introduced to polyvinyl chloride (PVC) to produce a modified PVC polymer. The polymer composite of new modified PVC polymer was blended with micro copper oxide as a reflecting mirror of UV light to enhance the photostability of PVC. Three different concentrations of micro copper oxide (0.01–0.03 wt.%) were mixed with the modified PVC and cast as a thin film. The photostability test has shown high resistance to photodegradation upon exposure to UV light. In this work, different approaches were applied to examining doped modified PVC's thin film efficiency against photodegradation after exposure to UV light for 300 h in an ambient atmosphere. The exhibited studies, such as infrared spectroscopy and weight loss percentage, have demonstrated the improvement of photophysical properties for modified PVC and blended modified films in comparison to blank PVC polymeric films. These outcomes are so interesting as they could contribute to reducing the consumption of PVC around the world hence its waste causing huge environmental problems for the marine ecosystem.

Fluorescence enhancement of near infrared cell membrane probe by β-cyclodextrin supramolecular interaction

In this paper, oxazolepyridine and coumarin units were combined to prepare cell membrane fluorescent probe (PM-A) through aldol condensation reaction. PM-A had long wavelength emission (665–739 nm), high molar extinction coefficient (around 3.14 × 104 M−1cm−1) and large Stokes shift (150–219 nm). The photo-stability test showed that PM-A had a high relative residual absorption (93%) after 6 h of continuous illumination. In addition, the supramolecular interaction between PM-A and β-cyclodextrin was evaluated and applied to cell imaging. Probe PM-A had no fluorescence in water, but had obvious fluorescence signal in β-cyclodextrin solution. With the addition of β-cyclodextrin (0–800 eq), the fluorescence quantum yield of PM-A increased from 0% to 45%. Laser confocal experiments showed that when only PM-A was added, the probe concentration needed to be 15 μM to image the cell membrane obviously. In sharp contrast, with the help of β-cyclodextrin solution, the concentration of probe PM-A only needed 0.5 μM to quick and high specificity image cell membranes. Moreover, PM-A had high photo-bleaching resistance and long retention time after adding β-cyclodextrin. These excellent properties of PM-A were of great significance to the study of cell membrane.

Noble-metal-free photosensitizers for continuous-flow photochemical oxidation of steroid hormone micropollutants under sunlight

Given the crucial role of noble metals in promoting singlet oxygen (1O2) production, the feasibility of relying on cheaper and more abundant metals remains challenging. This work investigates the continuous-flow photocatalytic degradation of steroid hormone micropollutants, achieved with photocatalytic membranes based on noble-metal (Pd) and noble-metal-free (Zn, Mn, free-base) porphyrins. Under solar illumination corresponding to one-sun equivalent for the wavelength range 350–1150 nm, Zn- or free-base porphyrin-coated membranes exhibit a similar decrease of 17β-estradiol concentration in the permeate from 100 ng L−1 down to 15–23 ng L−1 compared to the benchmark membranes coated with Pd-porphyrin. Due to the difference in 1O2 quantum yield generation upon immobilization, the noble-metal-free porphyrins demonstrate diminished removal of estrone or 17β-estradiol (up to 62% against 85%), when illuminated with intensity equivalent to one-sixth of terrestrial sunlight. Nevertheless, the Zn-complex photobleached 3–4 times slower than free-base and Pd-porphyrins during 125 h of accelerated aging. This photostability test revealed the half-life time for immobilized Zn-porphyrin equivalent to 209 days of outdoor exposure assuming the daily average illumination of 3 h. The findings highlight that Zn-porphyrin is slightly less effective than noble-metal analogue, but may outperform Pd-porphyrin in terms of photostability and price–performance ratio.

Essential Oils from Piper lhotzkyanum Kunth Leaves from Brazilian Atlantic Forest: Chemical Composition and Stability in Different Storage Conditions.

This work aimed to evaluate the impact of different storage conditions and light and temperature exposures on the visual aspect and chemical composition of the essential oil (EO) of Piper lhotzkyanum Kunth, obtained from leaves by hydrodistillation from a region of high altitude. For this purpose, aliquots of the EO were stored for up to 90 days (a) under a refrigerator condition of 5 ± 3°C, (b) under a long-term (LT) condition of 30 ± 2°C and 75 ± 5% relative humidity (RH) and an accelerated condition (AS) of 40 ± 2°C and 75 ± 5% RH, and (c) in a photostability test achieved in amber and colorless glass vials. The changes were monitored on days 0 (control), 60, and 90 for the refrigerator, LT, and AS conditions. All EO chemical analyses were assessed by GC-FID and GC-MS for quantification and identification, respectively. It is reported, for the first time, that the EO of P. lhotzkyanum is rich in the sesquiterpenes β-elemene and α-zingiberene. No significant changes in the EO was observed, revealing a minimal impact of temperature on the sample at the different storage conditions. However, there was a change in the content of α-zingiberene to bicyclogermacrene after exposure to light. The visual appearance of the samples was altered for all test conditions except the refrigerator condition. These results can potentially contribute to the product development of a bioactive EO from leaves of P. lhotzkyanum, a sesquiterpene rich natural material.

Design of cross-linked polyisobutylene matrix for efficient encapsulation of quantum dots.

Photoluminescent quantum dots (QDs) are a prominent example of nanomaterials used in practical applications, especially in light-emitting and light-converting devices. Most of the current applications of QDs require formation of thin films or their incorporation in solid matrices. The choice of an appropriate host material capable of preventing QDs from degradation and developing a process of uniform incorporation of QDs in the matrix have become essential scientific and technological challenges. In this work, we developed a method of uniform incorporation of Cu–Zn–In–S (CZIS) QDs into a highly protective cross-linked polyisobutylene (PIB) matrix with high chemical resistance and low gas permeability. Our approach involves the synthesis of a methacrylate-terminated three-arm star-shaped PIB oligomeric precursor capable of quick formation of a robust 3D polymer network upon exposure to UV-light, as well as the design of a special ligand introducing short PIB chains onto the surface of the QDs, thus providing compatibility with the matrix. The obtained cross-linked QDs-in-polymer composites underwent a complex photostability test in air and under vacuum as well as a chemical stability test. These tests found that CZIS QDs in a cross-linked PIB matrix demonstrated excellent photo- and chemical stability when compared to identical QDs in widely used polyacrylate-based matrices. These results make the composites developed excellent materials for the fabrication of robust, stable and durable transparent light conversion layers.

UJI FOTOSTABILITAS PIGMEN BIXIN PADA BENTONIT DAN BENTONIT TERPILAR-TiO2

One of the characteristics of the bixin pigment is its low photostability, which causes its limitations. There are many methods to improve the photostability of bixin. This study aims to study the rate of degradation of bixin in the form of an extract that will be impregnated in bentonite and TiO2 pillared bentonite. The photostability test was carried out by continuously illuminating the sample with ultraviolet (UV C) light for nine h. Bixin concentration was observed using a UV-spectrophotometer. The results showed that the impregnation of bixin extract on bentonite could increase the photostability of bixin from 14.4 h to 138.6 h. On the other, impregnation of bixin on TiO2 pillared bentonite increases the rate of bixin degradation. The half-life of bixin offered to this material is only 3.7 h. TiO2 pillared bentonite enrolls as a photocatalyst, which is enhanced photodegradation of bixin pigment. Keywords: bixin, bentonite, photostability, pigment, TiO2-pillared bentonite

Sol–gel Fe/TiO2 Magnetic Catalysts Applied to Selenium Photoreduction

The risks of selenium (Se) water contamination to human and aquatic life make it important to develop and apply efficient Se removal methods. Selenium photocatalytic reduction is an effective technique for this purpose, but it still suffers from limitations related to the photocatalyst recovery at the end of the process. In the present work, magnetic particles were coated with a titanium dioxide (TiO2) layer, using a sol–gel process, in order to obtain a magnetic recoverable Fe/TiO2 photocatalysts. The catalysts were prepared with different Fe concentrations and with or without thermal treatment, being then characterized by different techniques and applied in the Se photoreduction. Both calcined and non-calcined catalysts presented similar specific surface areas (19–29 m2 g− 1), but the latter showed better results in the photocatalytic tests (100% of Se removal in 15 min using the non-calcined 8% Fe photocatalyst). The photostability test performed using the best catalyst (non-calcined 8% Fe photocatalyst) indicated a decrease in the photoactivity from the second photocatalytic cycle onwards. Besides, the catalysts lost their magnetic properties after being calcined.

Effect of solid lipid nanoparticles system on the stability of Green Tea leaves (Camellia sinensis L. Kuntze) extract as sunscreen

Green tea (Camellia sinensis L.) is known to have activity as antioxidant and sunscreen due to its catechin compound. The major catechin-derived compound is epigallocatechin gallate (EGCG). However, EGCG in green tea leaves is unstable due to its rapid degradation and large molecular mass of 458 daltons, making it difficult to penetrate the skin. The purpose of this research is to formulate solid lipid nanoparticles (SLN) of green tea leaves ethanol extract using high speed homogenization and sonication method, as well as to evaluate SLN ability in improving extract stability as sunscreen using UV-Vis spectrophotometry. SLN formula contained 0,1% green tea leaves ethanol extract, and the most optimal formula was composed of 4% lipid (Precirol ATO 5:Gelucire 44/14) 4:1 and 1% Kolliphor P188 as surfactant. Characterization results showed particle size of 286.7 nm, polydispersity index 0.296, and zeta potential -3.7 mV. Photostability test using 120-minutes irradiation showed decrease in percentage of DPPH free radicals damping at 5.34% extract and 1.77% SLN for UVA, and 7.7% extract and 2.34% SLN for UVB.

Preparation of porphyrin sensitized three layers magnetic nanocomposite Fe3O4@SiO2@TiO2 as an efficient photocatalyst

A multifunctional photocatalyst was prepared by porphyrin sensitized core-shell nanocomposite Fe3O4@SiO2@TiO2 (FST) to degrade organic contaminants more effectively. Nanocomposite Fe3O4@SiO2@TiO2 (FST) modified by maleic anhydride (MA) to improve dispersion property, and as a bridge molecule to graft with 5,10,15,20-meso-tetra-(para-amino)-phenyl-porphyrin (TAPP) to obtain FST-g-TAPP, and characterized by XRD, SEM, FT-IR, BET, TGA. The results demonstrated the successful grafting of TAPP onto the FST surface and grafting content of TAPP was about 3.2%. The photocatalytic activity of FST-g-TAPP was evaluated by degrading rhodamine B (RhB) in the presence of H2O2 under visible light irradiation. After 3 h, the degradation efficiency of 5 mg FST-g-TAPP (94.66%) was significantly higher than that of FST-MA (78.28%) and pure FST (52.72%). In addition, the photostability test of FST-g-TAPP demonstrated that it is reusable and stable due to strong covalent bonds between TAPP and FST.