UVA Region Research Articles

Influence of high-k La2O3 interfacial oxide layer on the performance of GaN based Schottky barrier ultraviolet-B and A photodetection sensors

GaN based metal-semiconductor-metal (MSM) type Schottky heterojunction-based ultraviolet (UV) photodetectors (PDs) have already proven as an efficient candidate for photodetection applications. However, in real time applications, GaN based MSM type UV PD device display higher dark current, weak signal detection and required external bias are seriously limiting their usage. Therefore, self-powered interdigitated electrode type Cr/Cu/La2O3/GaN: MIS (metal-insulator-semiconductor) heterojunction visible blind UV PD has been fabricated and studied in UV-B and A region. The structure, morphology, chemical and optical parameters of La2O3 films were evaluated using GIXRD, AFM, XPS and UV–Vis techniques, respectively. The reported interdigitated Cr/Cu/La2O3/GaN: MIS UV PD device yielded a higher Schottky barrier height (SBH) of 0.95 eV (dark) and 0.89 eV (360 nm) indicating the formation of higher potential barrier. At an applied bias of 0 V, the fabricated GaN MIS PD yielded an UV to visible rejection ratio (R360/R400) of 1.62 × 102. In UV-A region (at 0 V of 360 nm), the fabricated Cr/Cu/La2O3/GaN: MIS UV PD device exhibited a peak responsivity of 28.9 mAW−1, D∗ of 3.57 × 1012 Jones and EQE of 19.2 %. On the other hand, in UV-B region (at 0 V of 310 nm) the MIS UV PD device exhibited a peak responsivity of 34.4 mAW−1, D∗ of 4.2 × 1012 Jones and EQE of 22.7 %. During 360 nm illumination (at 0 V), the temporal response measurements of GaN UV PD device yielded the best rise/fall times of 70 ms/141 ms. This work validates the fact that the high-k La2O3 thin film as an interfacial oxide layer at the metal/GaN interface provides a novel solution for the photo detection field in the self-powered mode i.e., without any external bias.

Lignin nanoparticles enable and improve multiple functions of photonic films derived from cellulose nanocrystals

Flexible photonic materials derived from cellulose nanocrystals (CNCs) have attracted significant attention, particularly in multifunctional sensors, intelligent detection, and anti-counterfeiting applications. However, the major bottleneck with traditional CNC photonic materials is the provision of flexibility and multifunctional properties which often comes with compromises in optical properties. To address these challenges, we incorporated organosolv lignin nanoparticles (LNPs) and polyethylene glycol (PEG) into CNC films. LNPs were produced from sugarcane bagasse using various solvents, resulting in nanoparticles with distinct structural and chemical properties, such as different sizes and surface chemistries. The addition of LNPs and PEG to CNC films led to enhanced flexibility, strong iridescence, improved thermal stability and superior UV-blocking performance. Interestingly, the intercalation of LNPs significantly improved the strain at break by 89.6 % with slight increase of 7.7 % and 23.1 % in tensile strength and young’s modulus respectively. Additionally, distinguished UV-blockage performance of up to 99.9 % in the UVB region and 94 % in the UVA region was also achieved in CNC-LNP-PEG films. The films exhibited varying responses to several organic solvents and HCl gas with reversible color changes. These responses were attributed to the distinct surface chemistries of the LNPs, which influenced their interactions with the CNC matrix through mechanisms such as hydrogen bonding and hydrophobic interactions. This study highlights the potential of CNC-LNP-PEG composite films for advanced applications in chemical safety and anti-counterfeiting measures, demonstrating the importance of composite formulation and processing conditions in achieving desirable properties.

In vitro photoprotective efficacy and photostability of synthesized star-shaped ZnO nanoaggregates associated with ethylhexyl methoxycinnamate and butyl methoxydibenzoylmethane

The heightened susceptibility to skin cancer correlates with exposure to ultraviolet (UV) radiation, which can induce various cutaneous injuries. Inorganic UV filters, like zinc oxide (ZnO), are extensively utilized in sunscreens owing to their capacity to scatter and reflect UV radiation. The efficacy of inorganic UV filters can be augmented across a wider spectrum through synergistic combinations with other active compounds, such as organic UV filters. In this study, we synthesized and evaluated the in vitro effectiveness of star-shaped ZnO nanoaggregates. The samples were obtained employing a simple and greener precipitation method in an aqueous solution. The synthesized ZnO nanoaggregates were characterized through X-ray diffraction, UV/Vis spectroscopy, and transmission electron microscopy. The characterization suggests the aggregation of nanocrystals, with hexagonal wurtzite geometry, enabling the formation of star-shaped particles. The irregular (non-flat) surface and high surface area combined with light absorption in the UVA region make the material susceptible to the application of sun protection. Sunscreens formulated with the synthesized ZnOng in conjunction with ethylhexyl p-methoxycinnamate (EHMC) and/or butyl methoxydibenzoylmethane (BMDBM) were evaluated for in vitro sun protection factor (SPF) and critical wavelength (cλ) using diffuse reflectance spectrophotometry with an integrated sphere. Photostability assessments were also conducted using artificial UV radiation. Sunscreen formulations containing ZnOng in combination with EHMC and BMDBM exhibited a substantial increase in in vitro SPF, approximately 990 % (from SPF 26 to 285). Furthermore, the synthesized ZnOng demonstrated higher in vitro efficacy compared to commercial ZnO active ingredients. Although all samples experienced reductions in SPF values during the photostability assay, ZnOng + EHMC + BMDBM retained a broad-spectrum profile (SPF > 15 and cλ > 370 nm). Based on the distinctive properties and in vitro performance of star-shaped ZnOng, we propose that this synthesized inorganic UV filter could serve as an alternative for enhancing the SPF of sunscreen systems while reducing the concentrations of organic UV filters.

Photoprotective and bioinspired cerium-encapsulating lignin nanocapsules for multifunctional UV protection applications

Herein, Kraft lignin (KL) was used to encapsulate cerium oxide to synthesize a sunscreen with broad-spectrum sun protection factor (SPF), reactive oxygen species (ROS) scavenging, and antiphotoaging properties. Cerium encapsulated kraft lignin nanoparticles (K@CeNP) displayed the smallest zeta-average size of 93 nm, radical scavenging activity (RSA%) of 99 % at 500 µg/mL, and superior UV-blocking performance in both UVA and UVB regions. The successful encapsulation of cerium oxide within KL was also evaluated by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The cytotoxicity, UVA-induced photoprotective assay, UVA-induced oxidative stress and antiphotoaging were accessed on human keratinocyte cell lines (HaCaT) and human dermal fibroblasts (HDFs). The UVA-induced photoprotective effect and ROS level was analysed by exposing HaCat and HDFs to UVA radiation levels of 1000 mJ/cm2.The biocompatibility and UVA-induced cell viability of K@CeNP were much higher than those of K-LNP at all tested concentrations. The in-vitro ROS level was assessed by a DCF-DA assay while the antiphotoaging-activity was analysed by the senescence associated- Beta gal (SA- β gal) activity. Immediately after irradiation, K@CeNP showed a pronounced effect, reducing ROS by 77 % at 80 µg/mL in comparison to UVA control group. In addition, treatment with K@CeNP led to significant reduction in the SA- β gal activity. These findings highlight the applicability of lignin-based sunscreen that offers multifunctional benefits, effectively protecting the skin against UV rays while providing antioxidant and antiphotoaging benefits.

Microwave enhanced carbon dots synthesis from eggshell membrane: Versatile applications in heavy metal ion sensing, strain free detection of fingerprints, UV shielding, food packing and anti-counterfeiting

In this study, a one-step microwave irradiation process combined with a sodium hydroxide (NaOH) solution allowed for the quick and easy synthesis of carbon dots (CDs) from eggshell membrane (ESM) ashes. The resultant CDs demonstrated exceptional selectivity for Fe3+ and excellent fluorescence (FL) with a quantum yield (QY) of 15.3%. Utilizing synthetic CDs, a sensitive nanoprobe is utilized to identify free Fe3+ within the 0-350μM (R2 = 0.9976) range, with a 0.281μM limit of detection (LoD). Additionally, the CDs were shown to be useful for intracellular Fe3+ detection applications because of their low cytotoxicity and biocompatibility. Investigations using real samples at 420 and 500nm excitation wavelengths showed promising results in terms of real-world application. In order to transform molecular data into FL signal outputs, a multi-input logic gate is also constructed. In the UV-A (93%), UV-B (88%), UV-C (98%) and HEBL (79%) regions, blue colour-emitting CDs had the maximum UV blockage, but pure polyvinyl alcohol (PVA) absorbed less than 22–30% of the light in all UV regions. The integration of CDs into the polymer improved the thermal characteristics of the PVA film. Additionally, testing of in vitro cell viability demonstrated that the CDs, when embedded in the PVA, did not cause cytotoxicity to the Neuroblastoma cell line (SH-SY-5Y). As a paradigm for perishable commodities, the effects of CDs and PVA were assessed on the shelf life of tomatoes. When fresh tomatoes were coated with CDs@PVA and PVA, weight and moisture loss were effectively decreased, according to the results of the long-term monitoring study. Throughout almost 34 days at room temperature, it also dramatically reduced the growth of fungi and prevented spoiling, all the while maintaining the fruits original colour and appearance. The CDs FL under 365nm UV light excitation makes them well-suited for creating fluorescent inks to deter counterfeiting. Additionally, the study explored the CDs exceptional FL properties for use as a luminescent fingerprint powder, aiding in the detection of latent fingerprints (LFPs) on various surfaces. The findings from this study highlight the potential of cost-effective and safe CDs for a range of applications, including non-cytotoxic UV blocking, active packaging, Fe3+ sensing, fingerprint detection, anti-counterfeiting (AC) measures and flexible nanocomposite (NC) films.

Tandem Acylation and Aromatization of Vinylogous Esters: A Regiospecific Approach to Resorcinyl Ketones.

This study demonstrates the direct conversion of vinylogous esters into selectively protected 6-acyl resorcinols (4-alkoxy/aryloxy-2-hydroxy arylketones) in a regiospecific manner. Resorcinyl ketones are first-time synthesized, diverging from their traditional roots, originating from non-benzenoid pool materials. Converting cyclohexenones into phenol- or resorcinol-based arylketones remains challenging due to the stability and reactivity issues of intermediate products. Addressing this critical gap, we introduce a novel strategy: sequential one-pot acylation and oxidative aromatization of vinylogous esters. This innovative approach aims to surmount the long-standing barrier, facilitating the synthesis of diverse resorcinyl ketones. Furthermore, this method proves valuable for the synthesis of functionalized diaryl ethers and in the total synthesis of bioactive natural products and drug molecules such as angolensin, isoliquiritigenin, demethylsorbicillin, ponganone VII, and ipriflavone. It is also useful for modifying bioactive acids and alcohols by introducing a resorcinol functionality in the late stage of synthesis. Synthetic analogues of oxybenzone demonstrated superior ultraviolet (UV) absorption properties, effectively covering the entire UV-A and UV-B regions, spanning from 230 to 410 nm.

Allometric Models for Estimating Above-Ground, Below-Ground and Total Biomass of Tea (<em>Camellia sinensis</em> (L.) O. Kuntze) Plants Grown in Uva and Up Country, Sri Lanka

This study was conducted to identify the dendrometric variables highly correlating with above-ground (AGB), below-ground (BGB) and total (TB) biomass of tea grown in Uva and Up Country Sri Lanka, develop allometric models to estimate AGB, BGB and TB of tea plants, and to investigate the applicability of already developed allometric models in other countries to Sri Lanka. Twelve experimental plots from TRIORCON field experiment at Tea Research Institute of Sri Lanka, and 18 farmer fields in Uva region, Sri Lanka were selected as the study sites. Representative tea plants were uprooted from the selected sites and seven dendrometric variables were measured. Fresh and dry AGB and BGB of the tea plants were determined. The best allometric models to predict AGB, BGB and TB using dendrometric variables were developed using multiple linear and non-linear regression analyses. Non-linear allometric models fitted best when predicting AGB and TB. Over 64% of total variability of AGB and TB was explained by these models using collar diameter at the soil level. Linear allometric fitted best when predicting BGB. Over 92% of total variability of BGB was explained by linear regression models using collar circumference, main-stem circumference, mean length and circumference at end of the primary branches. Leave-one-out cross validation showed strong positive (AGB and TB) and moderate positive (BGB) correlations between observed and predicted biomass values. Developed linear allometric models in comparison to those in literature showed better fit to data collected under Sri Lankan conditions and precisely estimated AGB, BGB and TB.

Photoactive self-cleaning zinc oxychloride coatings

Zinc oxychloride cement (ZOC) is considered a promising quick-drying material for fabricating photoactive coatings composed of three components: zinc oxide (ZnO), zinc chloride (ZnCl2), and water. However, its massive application has not been implemented due to the lack of research about its stability and mechanical performance. Thus, this article aims to provide insights about the self-cleaning photoactivity of ZOC coatings incorporated with titanium dioxide (TiO2) nanoparticles to boost the photocatalytic performance. Two stoichiometries of ZnO:ZnCl:H2O (112 and 415) were studied to investigate the influence of the molar ratio of the components on the physical and chemical properties. According to these results, no significant differences were observed in the physical and chemical properties between the two stoichiometries studied; however, the mechanical properties were affected. The coatings crystallized as simonkolleite Zn5(OH)8Cl2·H2O with a laminar hexagonal morphology, show high surface area, and absorbs light in the UVA region. The self-cleaning activity was evaluated using four model pollutants: Rhodamine B, Methylene blue, Orange G, and Carbon under accelerated weathering conditions. All the coatings were photoactive to decompose the pollutants from their surface and the addition of TiO2 nanoparticles did not significantly enhance the self-cleaning efficiency, but it improves the mechanical performance of the coatings. These results could be associated with the fact that TiO2 works as filler for voids in the coatings without affecting its settings. The stability of the coatings was confirmed after the exposure to accelerated weathering at high humidity conditions, which places them as an attractive, low-cost, and easy to apply self-cleaning material.

Cellular damage photosensitized by dasatinib, radical-mediated mechanisms and photoprotection in reconstructed epidermis

Dasatinib (DAS) is an anticancer drug employed in the treatment of certain hematological malignancies. Although DAS has been mainly developed for oral administration, it has recently garnered attention for its possible topical application. The use of topical drugs can cause photosensitivity, which is not listed as an adverse reaction for DAS. Since DAS absorbs UVA, it could potentially induce photosensitivity reactions and lead to oxidative damage to cellular targets. This study aims to investigate whether DAS exhibits phototoxic reactions on primary cellular targets in both solution and artificial skin, mimicking topical drug administration. It also examines the potential generation of highly reactive intermediates like organic radicals and ROS, which could trigger photosensitivity reactions. Upon DAS irradiation in the UVA region, the first transient species detected was the diradicaloid triplet excited state (3DAS∗) with an absorption maximum of around 490 nm, which was quenched by oxygen to produce singlet oxygen. Quenching experiments with linoleic acid and 3-methylindole indicated that radical-mediated (Type I) photosensitized damage to lipids and proteins is possible. However, the lack of triplet quenching with guanosine suggests that the Type II mechanism also plays a role in the photooxidation of biomolecules. Accordingly, the neutral red uptake phototoxicity test (photoirritation factor of 5) and the comet assay, revealed that this drug is photo(geno)toxic to cells. Moreover, investigations on lipid photoperoxidation, and protein and DNA photooxidation strongly support that different cellular compartments are potential targets for DAS-induced phototoxicity.Regarding its potential application in topical dermatological formulations, an O/W emulsion of DAS was prepared and tested in reconstructed human epidermis, and a significant phototoxicity was also demonstrated. Fortunately, this undesired side effect disappeared upon formulation of DAS along with a sunscreen. Thus, for topical treatments, the photosensitivity reactions induced by DAS can be prevented by using formulations including appropriate UVA filters.

A “core-shell” structure imparting both gas barrier and UV shielding properties for a PLA/ PGA/ PBS ternary blend film

The core-shell structure enhances polymer blend systems by orderly assembly and leveraging complementary properties. This study aims to enhance the flexibility and barrier properties of polylactic acid (PLA, L) by blending it with polyglycolic acid (PGA, G) for gas barrier and polybutylene succinate (PBS, B) for flexibility. Encapsulating PGA in a core-shell structure using PBS resolves PGA's rapid hydrolysis issue. The theoretical models predicting dispersion patterns based on spreading coefficients and interfacial tensions were validated through SEM observations, confirming the formation of a core-shell structure in the 5L1G4B ternary blend. Compared to the PLA/PBS binary blend film, samples with PGA (5L1G4B and 4L1G5B) exhibit higher elongation at break and tearing strength. For instance, the elongation at break of the 5L1G4B sample increases from 272.3 % of 6L4B to 470.85 %. The 5L1G4B showed comparable oxygen and carbon dioxide barrier properties to the 6L4B sample. The 5L1G4B and 4L1G5B samples show <2 % UV transmittance in the UVA region, indicating excellent UV shielding. The 5L1G4B blend film, with its mechanical properties, oxygen barrier, UV resistance, and biodegradability, is ideal for outer layer packaging film and has the potential to replace LDPE in packaging juice and dairy product bottles.

Carbon dots as a distinctive platform fabricated through a sustainable approach for versatile applications

Red-emitting carbon dots (R-CDs) have garnered significant interest owing to its exceptional fluorescence (FL) characteristics. In this study, we present a one-pot solvothermal synthesis for producing biomass-derived R-CDs, utilizing Birch leaves as the primary raw material. The R-CDs display high solubility in ethanol and demonstrate deep-red emission at 625 nm with narrowband characteristics. After conducting a selectivity assessment with different metal ions, it is observed that R-CDs demonstrate exceptional sensitivity and specificity specifically to Fe3+. This demonstrates a linear relationship up to a concentration of 500 μM, with a detection limit of 0.302 μM (S/N=3). In this research, we created photoluminescent and transparent composites made from polyvinyl alcohol (PVA) with embedded fluorescent R-CDs, using the solution casting method for fabrication. The synthesized R-CDs exhibit robust and consistent FL in solution, whereas, the R-CDs@PVA nanocomposites (NCs) films are transparent and exceptionally flexible. The optimized 0.08 wt% R-CDs demonstrated the most effective ultra violet (UV) blockage across the UV-A (76.84 %), UV-B (74.86 %), and UV-C (78.46 %) region. However, PVA alone absorbed < 25 % of the light in all UV regions. The study explored the shape memory and FL characteristics of the R-CDs@PVA NCs changed under varying conditions such as water, temperature and pH. In alkaline conditions, the FL intensity of the R-CDs@PVA NCs increased due to the deprotonation of the R-CDs surface. In addition, R-CDs dispersed within PVA exhibit superior ink-free patterned substrates, proving to be advantageous for non-destructive template relief printing. Furthermore, R-CDs serve as effective anti-oxidants, combating 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and mitigating the oxidative stress (OS) in red blood cells (RBCs) induced by sodium nitrite (NaNO2). They aid in the restoration of essential stress indicators, encompassing lipid peroxidation (LPO), protein carbonyl content (PCC), total thiol (TT), superoxide dismutase (SOD), and catalase (CAT). Furthermore, R-CDs restored the damaged liver, kidney, heart, and pancreas by regulating biochemical parameters. Furthermore, incorporated R-CDs into red light-emitting diodes (R-LEDs) and white light-emitting diodes (W-LEDs), thereby enhancing plant growth efficiency. The results of this study highlight the possible of R-CDs as non-toxic, UV blocking agents suitable for developing edible coatings and packaging. These properties suggest their applicability in the food industry, anti-counterfeiting (AC) measures, and biomedical applications.

Real-Time Ultraviolet Monitoring System with Low-Temperature Solution-Processed High-Transparent p-n Junction Photodiode with a Fast Responsive and High Rectification Ratio.

We introduce an enhanced performance organic-inorganic hybrid p-n junction photodiode, utilizing poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine] (PTAA) and ZnO, fabricated through a solution-based process at a low temperature under 100 °C. Improved interfacial electronic structure, characterized by shallower Gaussian standard deviation of the density-of-state distribution and a larger interface dipole, has resulted in a remarkable fold increase of ∼102 in signal-to-noise ratio for the device. This photodiode exhibits a high specific detectivity (2.32 × 1011 Jones, ) and exceptional rectification ratio (5.47 × 104 at ±1 V). The primary light response, concentrated in the optimal thickness of the PTAA layer, contributes to response over the entire UVA region and rapid response speed, with rise and fall times of 0.24 and 0.64 ms, respectively. Furthermore, this work demonstrates immense potential of our device for health monitoring applications by enabling real-time and continuous measurements of UV intensity.

LOV1 protein of Pseudomonas cichorii JBC1 modulates its virulence and lifestyles in response to blue light

Bacteria perceive light signals via photoreceptors and modulate many physiological and genetic processes. The impacts played by light, oxygen, or voltage (LOV) and blue light (BL) photosensory proteins on the virulence-related traits of plant bacterial pathogens are diverse and complex. In this study, we identified LOV protein (Pc-LOV1) from Pseudomonas cichorii JBC1 (PcJBC1) and characterized its function using LOV1-deficient mutant (JBC1Δlov1). In the dark state, the recombinant Pc-LOV1 protein showed an absorption band in UV-A region with a double peak at 340 nm and 365 nm, and within the blue-region, it exhibited a main absorption at 448 nm along with two shoulder peaks at 425 nm and 475 nm, which is a typical feature of oxidized flavin within LOV domain. The adduct-state lifetime (τrec) of Pc-LOV1 was 67.03 ± 4.34 min at 25 °C. BL negatively influenced the virulence of PcJBC1 and the virulence of JBC1Δlov1 increased irrespective of BL, indicating that Pc-LOV1 negatively regulates PcJBC1 virulence. Pc-LOV1 and BL positively regulated traits relevant to colonization on plant surface, such as adhesion to the plant tissue and biofilm formation. In contrast, swarming motility, exopolysaccharide production, and siderophore synthesis were negatively controlled. Gene expression supported the modulation of bacterial features by Pc-LOV1. Overall, our results suggest that the LOV photosensory system plays crucial roles in the adaptive responses and virulence of the bacterial pathogen PcJBC1. The roles of other photoreceptors, sensing of other wavelengths, and signal networking require further investigation.

Systematic tuning of optical and electronic properties of holey graphene quantum dots for UV applications

Graphene quantum dots (GQDs) have remarkably demonstrated themselves as an efficient non-toxic material whose optoelectronic characteristics could be suitably tailored by molecular engineering. In present work, the properties of GQDs have been modified by creating pores in between them and then passivating them with H, F, and O atoms particularly finding their applications in the Ultraviolet (UV) region. For these purposes, materials having an emission wavelength in the UVA region are desirable. It has been investigated that these pores significantly altered the bandgap of GQDs which in turn affected their optical properties. Transitions contributing to the highest peaks in absorption and photoluminescence spectra have been identified and their isosurface contour-maps have also been plotted to find out the nature of this transition. Emission-wavelengths of these holey GQDs have been discovered to fall in the desirable UVA range, which is perfectly suitable for their usage in UV A lamps, medical phototherapy.

Visible light triggers the formation of reactive oxygen species in monoclonal antibody formulations

Most monoclonal antibody formulations require the presence of a surfactant, such as polysorbate, to ensure protein stability. The presence of high concentrations of polysorbate have been shown to enhance photooxidation of certain protein drug products when exposed to visible light. The current literature, however, suggest that photooxidation of polysorbate only occurs when exposed to visible light in combination with UVA light. This is probable as peroxides present in polysorbate solutions can be cleaved homolytically in the UVA region. In the visible region, photooxidation is not expected to occur as cleavage of peroxides is not expected at these wavelengths.This report presents findings suggesting that the presence of one or more photosensitiser(s) in polysorbate must be a cause and is required to catalyse the aerobic oxidation of polysorbate solutions upon exposure to visible light. Our investigation aimed to clarify the mechanism(s) of polysorbate photooxidation and explore the kinetics and the identity of the generated radicals and their impact on monoclonal antibody (mAb) degradation. Our study reveals that when polysorbate solutions are exposed to visible light between 400 - 800 nm in the absence of proteins, discolouration, radical formation, and oxygen depletion occur. We discuss the initial formation of reactive species, most likely occurring directly after reaction of molecular oxygen, with the presence of a triplet state photosensitiser, which is generated by intersystem crossing of the excited singlet state. When comparing the photooxidation of PS20 and PS80 in varying quality grades, we propose that singlet oxygen possesses potential for reacting with unsaturated fatty acids in PS80HP, however, PS20HP itself exhibited no measurable oxidation under the tested conditions. The study’s final part delves into the photooxidation behaviour of different PS grades, examining its influence on the integrity of a mAb in the formulation. Finally, we examined the effect of photooxidation on the integrity of monoclonal antibodies. Our findings show that the exposure to visible light in polysorbate-containing mAb solutions at high PS concentrations of 4 mg·ml−1 results in increased monoclonal antibody degradation, highlighting the need for cautious evaluation of the correct PS concentration to stabilise protein therapeutics.

La3+-adjusted optical and ligand field parameters in low CoO impurities Na2O–ZnO borate glass matrix

The effect of La2O3 on the ligand field and optical properties of the current glass system was investigated. In detail, the absorption band at (493–499 nm) is ascribed to 4T1g (F) → 2T1g (H) transition of Co2+ in octahedral symmetry. The absorption band at (574–580 nm) is ascribed to 4A2 (4F)→4T1(4P) transitions of Co2+ in tetrahedral symmetry. On the other hand, the electronic transition at (639–644 nm) is attributed to 5T2g→ 5Eg transition of Co3+ in octahedral symmetry. Moreover, the redshift of the absorption edges reduces the optical bandgaps from 3.42 eV to 3.24 eV. Additionally, the La2O3-free glass sample exhibited a transition at ∼230 nm in the UVC region. However, this glass sample showed an displayed transparency in the UVA and UVB regions. Furthermore, the redshift of the absorption edges resulted in the glass sample with the highest La2O3 content (i.e., 8 mol%) becoming UVA transparent while blocking UVC and UVB regions. The obtained data regarding the ligand field parameters indicate an increase in the ligand field splitting (10Dq), reflecting the increased interplay strength between Co2+ in tetrahedral symmetry and its ligands. Also, the values of the nonlinear refractive index and nonlinear optical parameters increased due to the enhancement of basicity within the glass network. These findings suggest that the glass with the greatest concentration has the potential to be utilized as an optical filter that allows UVA while blocking UVC and UVB electromagnetic waves.

Effect of Light Sources on Transmittance of Commercially Available Contact Lenses.

Previous studies have suggested that light rays may interact with contact lenses, potentially affecting their transmittance. This study aimed to investigate the effects of visible and ultraviolet (UV)-A light sources on the transmittance of some commercially available daily, weekly, and monthly contact lenses. Nine commercially available soft contact lenses were irradiated with a solar simulator, light-emitting diode (LED) source, laser source, and UV-A source. The average transmittance of the tested lenses before and after irradiation in the UV, visible, and infrared light wavelength ranges was determined using an Agilent UV-visible spectrophotometer, model 8453. The results showed a partial or complete block of UV transmission at the UV-B region (300 nm) and the UV-A region (355 nm) by the Bio true daily contact lens, as well as the Acuvue Oasys, Avaira, and Biomedics 55 weekly lenses. At the visible region (555 nm), irradiation of the contact lenses by different light sources resulted in reduced light transmittance. At the infrared region (900 nm), the weekly and monthly contact lenses partially blocked infrared transmission, while the daily lenses showed either increased or decreased infrared transmission. Solar and artificial lighting, as well as high-powered lasers, constitute a major concern on the contact lenses' light transmission and optical properties. It is essential to develop soft contact lenses that have photoprotective properties while maintaining visible light transmittance.

Optical, Structural, and Dielectric Characteristics of Flexible PVA/PEG/ZnMn2O4/CuCo2O4/x wt % Melanin Blended Polymer Composites

Our research described in the current paper was aimed to alter the optical and dielectric characteristics of polyvinyl alcohol/polyethylene glycol blended polymers by incorporating different quantities of melanin and ZnMn2O4/CuCo2O4 to create flexible blended polymer composites suitable for applications like photocatalysis, capacitors, and different optoelectronic applications. The PVA/PEG/ZnMn2O4/CuCo2O4-x wt % melanin blended polymer composites were created using a casting technique. The structural properties of the fillers and various blends were investigated using an X-ray diffraction technique. A transmittance electron microscope was used to investigate the features of the ZnMn2O4/CuCo2O4. The optical properties of the PVA/PEG/ZnMn2O4/CuCo2O4-x wt % melanin blend composites, which included their linear and nonlinear optical parameters, were analyzed using a diffused reflectance technique. The direct and indirect optical energy gaps attained their lowest values (5.47, 3.22, and 2.97) and (5, 1.18) eV in PVA/PEG/ZnMn2O4/CuCo2O4 blended polymer. The doped blends exhibited superior absorbance efficiency in the UV spectra in both the UVA and UVB regions. In the UV and visible ranges doped blends with 15 and 10 wt % of melanin had the highest refractive index values, respectively. The highest dielectric constant and electric ac conductivity were achieved as the blend was loaded with 5 wt % melanin. The energy density value of the doped blend containing 10% melanin was the highest when compared to other doped melanin polymers. The maximum height electrical potential barrier of each blend was also calculated. The electric modulus was also studied. The intensities of the emission peaks in terms of fluorescence characteristics were reduced as the PVA/PEG blend was loaded with ZnMn2O4/CuCo2O4-x wt % melanin. In conclusion, the PVA/PEG/ZnMn2O4/CuCo2O4-x wt % melanin blended polymer composites are promising hybrid materials for use in a variety of applications.

Band Gap Modulation in Zn2TiO4 Spinels for Efficient UV-A Persistent Luminescence

Spinels are important materials for an application in bioimaging. The key advantage with spinel-type hosts is the presence of antisite defects, which act as charge reservoirs for trapping electrons and holes at complementary defect sites. This makes them a host system similar to a molecular system. Herein, we present a systematic approach to modulating the band gap of an inverse Zn2TiO4 spinel. With a change in ZnO concentration, the absorption band at 375 nm diminishes and disappears at a ZnO:TiO2 concentration of 1.40:1.00. The band gap of the material is modified from 3.30 to 4.40 eV. The crystal structure of the sample does not change drastically as determined using X-ray diffraction and Rietveld refinement. The Zn2TiO4 emits in the UV-A region with a lifetime in the time domain of `ns’. The sample also shows persistent luminescence of at least 15 min upon excitation with 254 nm with prominent emission in the UV-A region (300–390 nm). The present results open a new avenue for the synthesis of spinel hosts where the band gap can be modified with ease. The UV emission thus observed is expected to find usage in interesting applications like photocatalysis, anti-counterfeiting, water disinfecting, etc.

Synthesis and characterization of α-(4-(2,3-hydroxylpropoxy)phenylimino)-o-cresol Schiff base as an effective UV-absorber for ink systems

Schiff base is a diverse group of organic compounds and has potential as a UV absorber for ink systems due to its high UV protection, simple synthesis, and high dispersion in organic matrices. In this work, a novel Schiff base α-(4-(2,3-dihydroxylpropoxy)phenylimino)-o-cresol (named GMA-I) was synthesized and investigated as a UV absorber for ink system. The UV-protection of GMA-I was evaluated on ink-coated duplex substrate samples via color measurement using an accelerated UV test chamber. The results showed that the GMA-I exhibited strong absorption in both UVA and UVB regions with an extra high molar absorption coefficient of 43,554 M−1 cm−1, and high thermal stability of 271.4 °C. Interestingly, the GMA-I showed high UV protection for ink platform at low content of 2 wt% thank to the intramolecular proton transfer mechanism and therefore potential as a UV absorber additive for ink systems.