UVA Region Research Articles

Functional composite hydrogels entrapping polydopamine hollow nanoparticles for highly efficient resistance of skin penetration and photoprotection

Living organisms tend to evolve various naturally photoprotective mechanisms to avoid photodamage. Among them, polydopamine (PDA) is an effective sunscreen, a mimic of melanin, which is the main functional component of the photoprotective system of human skin. However, the concerns of its dark color, skin penetration and photoprotective efficiency remain yet to be solved. Herein, we have constructed melanin-inspired nanocomposite hydrogels (CS-PDAh-GP-HA) for photoprotection, in which PDA was prepared as hollow nanoparticles (PDAh NPs) and entrapped in a physically cross-linked hydrogel (CS-GP-HA) formed by chitosan (CS) and hyaluronic acid (HA) using β-glycerophosphate (β-GP) as a modulator. The CS-PDAh-GP-HA hydrogels exhibit a shear-thinning flow behavior with an elastic modulus of 300 Pa with the gel-sol transition temperature maintained at about 37 °C simply by adjusting the β-GP content in the hydrogels. The CS-PDAh-GP-HA hydrogels also possess excellent resistance toward skin penetration. The photoprotective performances of CS-PDAh-GP-HA hydrogels were evaluated by the determination of sun protection factor (SPF) and in vitro UVA protection efficacy (UVAPE) along with UV–Vis spectroscopy. Compared with the TiO2 nanoparticles in CS-GP-HA hydrogel, the CS-PDAh-GP-HA hydrogels show stronger shielding ability in both UVA and UVB regions. When protected by the CS-PDAh-GP-HA hydrogels, the cell viability of NIH-3T3 fibroblasts increases to 96% while it was only 14% in the case of non-protecting group. These results suggest that the CS-PDAh-GP-HA hydrogels could efficiently shield the UV irradiation and protect the skin from photodamage. This work introduces PDA-based nanocomposite hydrogels with safe, biocompatible and photoprotective properties, and provides a melanin-mimicking photoprotection system for the application in sunscreens.

Evidence of a Photoinduced Electron-Transfer Mechanism in the Fluorescence Self-quenching of 2,5-Substituted Selenophenes Prepared through In Situ Reduction of Elemental Selenium in Superbasic Media.

A series of new 2,5-disubstituted selenophene derivatives are described from elemental selenium and 1,3-diynes in superbasic media. The activation of elemental selenium in a KOH/DMSO system allows cyclization with conjugated diynes at room temperature. The cyclization reaction is extended to a broad range of functional groups, for which photophysics were experimentally and theoretically investigated. The selenophene derivatives present absorption maxima in the UV-A region and fluorescence emission in the violet-to-blue region. Fluorescence decay profiles were obtained showing a monoexponential decay with fast fluorescence lifetimes (∼0.118 ns), as predicted by the Strickler-Berg relations. In general, in both investigations, no dependence on the solvent polarity on the absorption and emission maxima location was observed. On the other hand, solvents and substituents are shown to play a role in the fluorescence quantum yield values. In addition, a fluorescence self-quenching behavior could be observed, related to a photoinduced electron-transfer mechanism. Theoretical calculations performed at the MP2/ADC(2)/cc-pVDZ level of theory were performed in order to investigate the photophysical features of this series of selenophene derivatives.

UV‐Shielding and Clusteroluminogenic Cellulose‐Based Films with Tuneable Wettability and Permeability for Dually Self‐Indicating Food Packaging

AbstractFood packaging plays a vital role not only in extending the shelf‐life and ensuring the safety and quality of food, but also in reducing the occurrence of food loss and waste. This study reports the generation of biocompatible and tuneable cellulose‐based films, which show strong UV absorbing capacity in both UVA and UVB regions to protect the packaged food from UV degradation. By taking advantage of the process of clusterization‐triggered emission, the films can indicate, by displaying changes in the intensity of luminescence, not only their properties but also the status of the packaged food. The protective and dually self‐indicating capacity of the films in food packaging is demonstrated by using frozen chicken breast as a food model. Together with their negligible toxicity, good barrier properties, and high tunability, the films warrant further development as dually self‐indicating materials for food packaging applications.

Hydrogel sunscreen based on yeast /gelatin demonstrates excellent UV-shielding and skin protection performance

Traditional organic and inorganic sunscreens suffer from the disadvantages of low stability and poor biocompatibility. In the study, we developed a novel hydrogel sunscreen based on the yeast and gelatin, which demonstrated excellent UV protection property and broad absorption of UV across UVA and UVB region. Yeast was used as effective component and gelatin as matrix to fabricate the hydrogel, which is high hydrated and reasonable to simulate natural living tissue. As a common probiotic, yeast shows safety and satisfactory UV protection capability. Furthermore, the hydrogel sunscreen shows excellent biocompatibility and UV protection performance both in vitro and in vivo. Moreover, they can be prepared conveniently and provide an eco-friendly strategy, which provides experience and inspiration of probiotics in the cosmetics application.

Adonis amurensis Is a Promising Alternative to Haematococcus as a Resource for Natural Esterified (3S,3'S)-Astaxanthin Production.

Astaxanthin (AST) characteristics and pigment productivity of Adonis amurensis, one of the few AST-producing higher plants, have not yet been studied extensively. In this study, the geometrical and optical isomers of AST in different parts of the A. amurensis flower were determined in detail, followed by a separation of the all-trans AST using HPLC chromatography. AST extracted from the flower accounted for 1.31% of the dry weight (dw) and mainly existed in the di-esterified form (>86.5%). The highest concentration was found in the upper red part of the petal (3.31% dw). One optical isomer (3S, 3′S) of AST, with five geometrical isomers (all-trans, 9-cis, 13-cis, 15-cis, and di-cis) were observed in all parts of the flower. All-trans AST was the predominant geometrical isomer accounting for 72.5% of the total content of geometric isomers in total flower, followed by the 13-cis, and 9-cis isomers. The all-trans AST isomer was also isolated, and then purified by HPLC from the crude oily flower extract, with a 21.5% recovery yield. The cis-AST extracted from the combined androecium and gynoecium gives a very strong absorption in the UVA region due to a high level of cis, especially di-cis, isomers, suggesting a prospective use in the preparation of anti-ultraviolet agents. The production cost of AST from Adonis flowers can be as low as €388–393/kg. These observations together with other factors such as the low technology requirement for plant culturing and harvesting suggest Adonis has great potential as a resource for natural esterified (3S,3′S)-AST production when compared with Haematococcus culturing.

Bilayer films of poly(ε‐caprolactone) electrosprayed with gum rosin microspheres: Processing and characterization

Bilayer systems, consisting of electrosprayed gum rosin microspheres (eGR) and poly(ε‐caprolactone) (PCL), were prepared. First, the electrospraying processing conditions of GR in two different solvents, dichloromethane, and chloroform, were optimized. Various electrospraying polymeric solution flow rates and applied voltages were tested and morphologically analyzed in terms of particle size distribution and microspheres density. The conditions at which a homogeneous and narrow microspheres size distribution was achieved were chosen as the best for each solvent. The eGR was deposited onto a compression‐molded PCL film to obtain the bilayer systems. The bilayer systems were characterized by their visual appearance, microstructural analyses, thermal and mechanical performance, and surface wettability. It was determined that the mechanical and thermal behavior of PCL film was not affected due to the addition of the eGR microspheres layer. Meanwhile, the eGR layer considerably changes the surface color of the PCL film, reduces the film transparency, and produces a blocking effect in the UVB region and high blockage in the UVA region. In addition, the microspheres layer presents a tunable hydrophobicity depending on the solvent used, reaching values of ultrahydrophobic surfaces. Thus, the obtained result reveals a great potential to easily process bilayer systems with high interest in sustainable agricultural, packaging, and/or biomedical applications.

Unveiling the nonadiabatic photoisomerization mechanism of hemicyanines for UV photoprotection

In this work, the nonadiabatic energy relaxation mechanism of hemicyanines for UV photoprotection were investigated by using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) method for the first time. The absorption spectra and potential energy surfaces (PESs) of four hemicyanines with different positions of substituents were presented. The maximum absorption peaks of the four hemicyanines are located in the UVA region. In addition, all these hemicyanine molecules also have light absorption in both the UVB and UVC regions. At the same time, we found that the trans–cis photoisomerization PESs of all these hemicyanines have a significant conical intersection (CI) point between the first excited state and the ground state. Herein, it was first demonstrated that the UV energy absorbed by the hemicyanines could be dissipated nonadiabatically through the CI point by using the trans–cis photoisomerization dynamics mechanism. This work proves that hemicyanines have the possibility to be applied for UV photoabsorbers, and provides important basis for designing new type of hemicyanines for UV photoprotection.

Films Based on Mater-Bi® Compatibilized with Pine Resin Derivatives: Optical, Barrier, and Disintegration Properties

Mater-Bi® NF866 (MB) was blended with gum rosin and two pentaerythritol esters of gum rosin (labeled as LF and UT), as additives, to produce biobased and compostable films for food packaging or agricultural mulch films. The films were prepared by blending MB with 5, 10, and 15 wt.% of each additive. The obtained films were characterized by optical, colorimetric, wettability, and oxygen barrier properties. Moreover, the additives and the MB-based films were disintegrated under composting conditions and the effect of each additive on the biodegradation rate was studied. All films were homogeneous and optically transparent. The color of the films tended to yellow tones due to the addition of pine resin derivatives. All the formulated films presented a complete UV-transmittance blocking effect in the UVA and UVB region, and those with 5 wt.% of pine resin derivatives increased the MB hydrophobicity. Low amounts of resins tend to maintain the oxygen transmission rate (OTR) values of the neat MB, due to its good solubilizing and compatibilizing effects. The disintegration under composting conditions test revealed that gum rosin completely disintegrates in about 90 days, while UT degrades 80% and LF degrades 5%, over 180 days of incubation. As expected, the same tendency was obtained for the disintegration of the studied films, although Mater-Bi® reach 28% of disintegrability over the 180 days of the composting test.

Learning to Live with Covid-19: MSMEs Perception and Strategies on Business Promotions, Uva region-Sri Lanka

Within the dynamic external environment, the external shocks might create either opportunities or challenges to business. The Pandemic of COVID –19 also an unpredicted, and highly vulnerable, and highly affecting external shock to the business segments. Therefore, this study would focus on the promotional tools and the perception of Micro, Small, and Medium scale Enterprises (MSMEs) during the Pandemic. Data gathered from Uva region MSME’s, via interview method, whereas the qualitative analysis-Thematic analysis method has been adopted. The findings highlight four parental themes; (a) Formal marketing Strategies, (b) Informal marketing Strategies, (c) Virtual Marketing Platform, and (d) Patriotic Marketing. As recommendations, strategies for MSME sector have been proposed. Keywords: business promotions, Covid-19 pandemic, marketing, perception, Small and Medium Enterprises DOI: 10.7176/EJBM/13-10-03 Publication date: May 31 st 2021

A Facile Approach for Fabrication Superhydrophobic and UV-blocking Cotton Fabrics with Self-cleaning Properties

A facile method to fabricate UV blocking superhydrophobic cotton fabric based on the deposition of TiO2 sol followed by surface modification with stearic acid is presented here. TiO2 and STA-TiO2 coated cotton fabrics were characterised by scanning electron microscopy, X-ray diffraction studies and X-ray photoelectron spectroscopy. The UV transmittance spectral studies showed that the STA-TiO2 coated cotton had excellent UV blocking property in both UV-A and UV-B regions and in fact the hydrophobicity did not affect the UV blocking property of TiO2 coated cotton. Moreover, the STA-TiO2 coated cotton fabric had outstanding self-cleaning property which can be effectively used for oil-water separation studies. Further, the modified cotton exhibited excellent chemical durability and mechanical stability. Hence, this work can be exploited for industrial applications for the fabrication of textiles with superhydrophobic, UV blocking and self-cleaning characteristics.

Studies to explore the UVA photosensitizing action of 9-phenylacridine in cells by interaction with DNA

Acridine and its derivatives are well known for their DNA binding properties. In this report, we present our findings on evaluating different binding parameters of the interaction of 9-phenylacridine (ACPH) with DNA. Absorption spectroscopic studies including standard and reverse titration, the effects of ionic strength and temperature on titration, and Job plot analysis were done to calculate the binding constant and determine the different thermodynamic parameters and stoichiometry of the binding. Spectrofluorimetry and circular dichroism (CD) spectral titration were also utilized to confirm these findings. The results indicated that ACPH binds to DNA reversibly through non-electrostatic interactions by hydrogen bonding and van der Waals interactions. The binding constant and the number of binding sites were of the order 103 M–1 and ≈2, respectively with a binding stoichiometry of 1:4. The binding of ACPH with DNA was spontaneous, exothermic and enthalpy-driven. The extent of uptake of ACPH in B16 melanoma cells was estimated. As this compound absorbs in the UVA region, the effect of treatment with ACPH prior to UVA exposure was assessed to evaluate its phototoxicity in these cells. Our results indicated that the binding to DNA enhanced damage to sensitize cells to killing through apoptosis. Our findings indicated its potential to act as a photosensitizer.

In situ synthesize of ZnO nanoparticles on cotton fabric by laser ablation method; antibacterial activities

In this research work, ZnO nanoparticles were produced by pulsed laser ablation method, employing the fundamental wavelength of pulsed Nd:YAG laser of 1064 nm and 7 ns pulse width in deionized water. Four sizes of nanoparticles were produced using different pulse numbers of laser. Simultaneously cotton fabric samples were placed near the Zn target in the ablation container. The ZnO nano particles were in situ synthesized on cotton samples. Characteristics of produced nanoparticles were examined using excitonic absorption peak and Fourier transform infrared (FTIR). X-ray diffraction pattern and dynamic light scattering (DLS) measurement were employed to determine the crystalline structure and size distribution of nanoparticles respectively. Morphology of nanoparticles were observed using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Reflection and transmittance spectra of treated cotton fabrics were measured and compared using spectrophotometer. Results show that transmittance of treated cotton is less than untreated one in UVA and UVB region. Also inductively coupled plasma device were used to study the amounts of nanoparticles on the cotton fabrics before and after 20 cycles of washing. Finally, the antibacterial properties of ZnO nanoparticles on Staphylococcus Aureus contaminated cotton fabric were tested. Results show that Staphylococcus bacteria may not survive on the treated textile even after 20 cycles of washing.

BN adamantane isomers: an optical absorption spectrum study

In this work, we have systematically investigated the structural, electronic, and optical absorption properties of the boron nitride (BN) adamantane isomers (B $$_x$$ N $$_{10-x}$$ , with x= 4, 5 or 6), using both DFT and TD-DFT methods. These isomers were built by replacing carbon atoms of the adamantane molecule by boron and nitrogen atoms and keeping all isomers in closed-shell electronic configuration. Optimized nanostructures indicate that these BN adamantane exhibit good stability. In addition, the current study indicates that the new BN-isomers have an excellent absorption in the UV-C region, and a moderate absorption in the UV-B and UV-A regions. These characteristics enable this new BN adamantane as potential candidates to be used in the development of new nano-optoelectronic devices.

Determining the photostability of avobenzone in sunscreen formulation models using ultrafast spectroscopy.

Avobenzone is an ultraviolet (UV) filter that is often included in sunscreen formulations despite its lack of photostability. Its inclusion is necessary due to few existing alternatives for photoprotection in the UVA region (320-400 nm). To better understand and predict the photostability of avobenzone, ultrafast transient electronic absorption spectroscopy (TEAS) has been used to study the effects of solvent (including emollients), concentration and skin surface temperature on its excited-state relaxation mechanism, following photoexcitation with UVA radiation (∼350 nm). Subtle differences between the excited-state lifetimes were found between the systems, but the TEAS spectral features were qualitatively the same for all solution and temperature combinations. Alongside TEAS measurements, UV filter/emollient blends containing avobenzone were irradiated using simulated solar light and their degradation tracked using steady-state UV-visible spectroscopy. Sun protection factor (SPF) and UVA protection factor (UVA-PF) assessments were also carried out on representative oil phases (higher concentration blends), which could be used to formulate oil-in-water sunscreens. It was found that there was an apparent concentration dependence on the long-term photoprotective efficacy of these mixtures, which could be linked to the ultrafast photodynamics by the presence of a ground-state bleach offset. This combination of techniques shows potential for correlating long-term behaviours (minutes to hours) of avobenzone with its ultrafast photophysics (femtoseconds to nanoseconds), bridging the gap between fundamental photophysics/photochemistry and commercial sunscreen design.

Ultrafast spectroscopic study on non-adiabatic UV protection mechanism of hemicyanines

In this work, we firstly elucidated the ultra-violet light protection dynamics mechanism of the typical hemicyanines, i.e. Hemicy and DHemicy, by combining the theoretical calculation method and the transient absorption spectra. It is theoretically and experimentally demonstrated that both Hemicy and DHemicy have strong absorption in UVC (200−280 nm), UVB (280−300 nm), and UVA (320−400 nm) regions. More-over, after absorbing energy, Hemicy and DHemicy can jump into the excited states. Subsequently, Hemicy and DHemicy relax to S0 states from S1 states rapidly by the non-adiabatic transition at the conical intersection point between the potential energy curves of S1 and S0 states, and are accompanied by the trans-cis photoisomerism. The transient absorption spectra show that trans-cis photoisomerization occur within a few picoseconds. Thus, the ultraviolet energy absorbed by Hemicy and DHemicy could be relaxed ultrafastly by the non-adiabatic trans-cis photoisomerization processes.

Simple, green, ultrasound-assisted preparation of novel core-shell microcapsules from octyl methoxycinnamate and oligomeric proanthocyanidins for UV-stable sunscreen.

Without sunscreens, UV rays in sunlight cause skin damage, ranging from dark spots and premature aging to skin cancer. Present sunscreens, however, are readily photodegraded, producing highly reactive radicals that can damage cells. To address this problem, we have now used ultrasound to prepare core–shell microcapsules, which offer improved protection against UV light and improved UV stability. The composite microcapsules have oligomeric proanthocyanidins (OPCs), which are amphiphilic plant-derived secondary metabolites, as the shell and octyl methoxycinnamate (OMC), which is a UVB absorber, as the core. The polyphenolic flavonoid structure of OPCs improves the UV stability of OMC and thus avoids the skin damage caused by OMC photodegradation products. In the microcapsules, π–π stacking interactions between OPCs and OMC molecules enhance the ability of OMC to absorb UV radiation and extend the absorption range from the UVB region (280–320 nm) to include the UVA and UVC regions (200–400 nm). The composite microcapsules were shown to be stable on storage and to be non-irritant to human skin. The ultrasound-assisted preparation of OMC/OPCs composite microcapsules is simple, efficient and green and provides a feasible strategy for the development of novel, more effective, sunscreens.

Formation of ZnO nanoparticles in the presence of Tannic acid

Zinc Oxide nanoparticles (ZnO NPs) have received abundance attention due to their ability to provide as a good semiconductor and UV absorbance materials. In this research, ZnO NPs are synthesised by hydrothermal method which employed a green synthesis method of which fully assisted by the Tannic Acid (TA). The controllable morphologies and mean sizes of ZnO NPs are observed to increased due to aggregation that occurred due to the influence of acidic medium (TA molecule). The morphological properties are discussed based on the TEM and FESEM images which indicated the average size of 14 nm and 32.7 nm for ZnO NPs and ZnO-TA NPs obtained, respectively. Meanwhile, the optical properties are discussed based on the UV–Vis absorbance spectroscopy results. The UV absorbance performance showed the behavior of absorbance peak at shorter wavelength as the ZnO NPs are capped with TA. The absorbance peak is shifted from UV-A region to UV-C region which indicated the transition from ZnO NPs to ZnO-TA respectively.

Facile and scalable design of light-emitting and ROS-generating hybrid materials made of polyurea gels embedding a molybdenum cluster-based salt

Here, we demonstrate a facile and scalable preparation via sol-gel chemistry of hybrid polyurea gels containing various amounts of a phosphorescent inorganic octahedral molybdenum cluster-based ternary salt, namely Cs2Mo6Br14. The influence of the Cs2Mo6Br14 content (1-10 wt%) on the polyurea matrix and its physical properties are studied in depth by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray fluorescence microanalysis (μ-XRF). Regardless of the amount of cluster loaded into the polyurea, the integrity of these species was preserved and their dispersion is homogeneous as shown by μ-XRF mapping. Spectroscopic-structural analyses reveal a significant increase of the chain mobility (glass transition temperature Tg) from -65 °C to -55 °C after the incorporation of Cs2Mo6Br14 (DSC analyses). The FTIR studies show that the homogeneity of the dispersion is ensured by supramolecular interactions between the ether-type oxygen atoms of the PEO chains and the cluster compound. Photoluminescence studies show that the metal cluster emission properties are well retained within the host matrix whatever the loaded content. Such a combination of materials demonstrates the feasibility to fabricate a rubber NIR-emitting device. Moreover, the loaded polyurea is also able to produce reactive oxygen species (ROS) upon irradiation in the UV-A region, opening new perspectives as versatile membranes in the field of photodynamic therapy.

Technical efficiency of organic tea smallholders: Evidence from Uva region of Sri Lanka

Today the society is moving towards sustainable agriculture, as a sustainable farming system, where cultivation is carried out without using chemically synthesized products such as urea, ammonium sulphate, pesticides, herbicides, hormones, activators, etc. With the introduction of organic agriculture to the world, organic tea also became important. Farmer productivity is one of the most important concerns in this regard. In the short run, the farmer productivity can be raised by improvement in technical efficiency. However, there is dearth of empirical evidence on technical efficiency of tea cultivation in Sri Lanka. Hence this article contributes to the pertinent literature by providing estimates of a stochastic frontier production model in a sample of organic tea smallholders in Diyathalawa region of Badulla district in Sri Lanka where the highest number of smallholders cultivate organic tea. The results reveal that the mean technical efficiency of organic tea smallholders is 24.7% implying that there is a scope of further increasing the output by 75.3%. Furthermore, livelihood diversification and crop diversification activities of smallholders contribute to decrease the efficiency.

High sensitive and stable self-powered solar-blind photodetector based on solution-processed all inorganic CuMO2/Ga2O3 pn heterojunction

Solar-blind photodetection systems, which can convert solar-blind deep ultraviolet light into an electrical signal, have been designed for practical use owing to their high sensitivity and accuracy. As one of the most suitable semiconductors for solar-blind photodetection, β-Ga2O3 can construct a pn type photodetector with another semiconductor material to meet the demands of energy savings, miniaturization and high efficiency. As a kind of natural p-type material, delafossite semiconductor materials CuMO2 (M = Al3+, Ga3+, In3+, Cr3+) have attracted much attention recently. The band alignment of CuMO2 is staggered with that of n-type β-Ga2O3; hence, the photogenerated electrons and holes tend to transfer through the interface in the opposite directions, resulting in spatial separation of charge carriers. Meanwhile, the fast hole diffusion coefficient (10−2–101 cm2 V−1 s−1) of CuMO2 guarantees the transport of holes, which is difficult in β-Ga2O3 owing to its intrinsic electronic structure. More importantly, compared with the widely used p-type materials, CuMO2 materials are almost insensitive to UVA light owing to the forbidden intrinsic direct transitions between the conduction and valence bands. Hence, the CuMO2/β-Ga2O3 pn junction photodetector exhibits high sensitivity, and the working spectral region is not extended to the UVA region. In this study, n-β-Ga2O3/p-CuMO2 (M: Ga3+, Cr3+) pn junction photodetectors were prepared by a simple solution process method. Due to the high crystallinity of the as-grown CuGaO2 and CuCrO2, the CuGaO2/β-Ga2O3 and CuCrO2/β-Ga2O3 pn junction photodetectors demonstrate an ultralow off state current of 51/61 fA, a superhigh on-to-off state current ratio of 2.3 × 104/3.5 × 104 and a high rejection ratio (R254/R365) of 2 × 104/2.8 × 104 under a bias of 0 V. The CuMO2/β-Ga2O3 pn junction photodetector satisfies the requirements of high sensitivity, stable and energy saving and has wide practical application prospect in solar-blind detection systems.