UVA Light Research Articles

Morphological and palaeoecological aspects of fossil insects unveiled by UV-A light

Studying insect fossils, particularly those preserved as compressions in sedimentary matrices, can be difficult due to the taphonomic processes that often result to poor preservation and contrast of structures compared to the embedding matrix. To address this, we propose a user-friendly and simple methodology based on UV-light to study insect fossils and select specimens of interest for more advanced imagery exploration. While UV-light imaging has been previously applied to compressions of arthropod fossils, it typically involved laser light sources. Our approach allows the investigation of fossils using an affordable, compact, and portable UV-light source, along with a simple and replicable low-cost protocol.•The methodology is based on UV-light induced natural fluorescence of sediment and fossil remains.•UV-light is effective on compression fossils to gain natural contrast and enhance observation of body structures like veins or setae on wings.•UV-light is effective to reveal palaeoecological information such as pollen grains preserved on specimens, especially near or on putative pollinator or pollen-eating taxa.

UiO-66-NDC (1,4-naphthalenedicarboxylic acid): A versatile metal-organic framework-based catalyst for photocatalytic degradation of dye chemicals

Metal-organic frameworks (MOFs) have received significant attention for their use as photocatalysts and photocatalyst supports. These materials have several benefits, including stability, catalyst reusability, tunability, and the capacity for post-reaction separation. Here, the potential applications of UiO-66-NDC as a photocatalyst for the degradation of reactive orange 16 (RO16), methyl orange (MO), and rhodamine B (RhB) were investigated. UiO-66-NDC was chosen for photocatalytic dye degradation due to its large surface area, adjustable characteristics, stability, effective light absorption, capacity for charge separation, and adaptability in design. UiO-66-NDC was synthesized the solvothermal process and its solid-state structure was characterized by solid-state methods, including UV-DRS, FTIR, zeta potential, PXRD and SEM measurements. The photocatalytic studies were performed by subjecting dye solutions with certain concentrations to UVA light irradiation in the presence of UiO-66-NDC. UV–Vis. spectroscopy was used to monitor the degradation process, which made it possible to calculate the degradation rate constants and the percentage of dye removal. The removal efficiency of adsorption, which was also examined, was at a minimum (17 % for RO16, 48 % for MO, and 25 % for RhB). The degradation of the dyes by UiO-66-NDC showed excellent photocatalytic activity, with degradation rates for RO16, MO, and RhB of 91 %, 93 %, and 81 %, respectively (300 mg/L catalyt; 20 ppm dye conc.). It was determined that the optimal concentration of catalyst was 300 mg/L. The reusability of UiO-66-NDC was successfully demonstrated through five successive cycles. The •OH radical was identified as the active species in photocatalysis. It was possible to remove 97 % of RO16, 99 % of MO, and 95 % of RhB at a high starting dye concentration (15 mg/L).

Application of Photodynamic Therapy with 5-Aminolevulinic Acid to Extracorporeal Photopheresis in the Treatment of Cutaneous T-Cell Lymphoma: A First-in-Human Phase I/II Study.

Extracorporeal photopheresis (ECP) is a therapeutic modality used for T-cell-mediated disorders. This approach involves exposing isolated white blood cells to photoactivatable 8-methoxypsoralen (8-MOP) and UVA light, aiming to induce apoptosis in T-cells and thereby modulate immune responses. However, conventional 8-MOP-ECP lacks cell selectivity, killing both healthy and diseased cells, and has shown limited treatment efficacy. An alternative approach under investigation involves the use of 5-aminolevulinic acid (ALA) in conjunction with light, referred to as ALA-based photodynamic therapy. Our previous ex vivo studies suggest that ALA-ECP exhibits greater selectivity and efficiency in killing T-cells derived from patients with T-cell-mediated disorders compared to those treated with 8-MOP-ECP. We have conducted a clinical phase I-(II) study evaluating ALA-ECP safety and tolerability in cutaneous T-cell lymphoma (CTCL). Here, 20 ALA-ECP treatments were administered to one CTCL patient, revealing no significant changes in vital signs. Two adverse events were reported; both evaluated by the Internal Safety Review Committee as non-serious. In addition, five conceivable events with mainly mild symptoms took place. During the study period, a 53% reduction in skin involvement and a 50% reduction in pruritus was observed. In conclusion, the results indicate that ALA-ECP treatment is safe and well tolerated.

Contrasting light capture strategies between shade-tolerant and -intolerant tree seedlings responding to solar canopy spectral composition

Forest regeneration is a crucial ecological process for promote self-reproduction and restoration, which is essential for maintaining complex community structure and preserving biological resources. Although sunlight have been considered as the main driver of forest regeneration, how light quality shapes functional traits of seedlings is poorly understood in the forest understorey, where spectral compositions of solar radiation change dramatically. We investigated the responses of 15 typical functional traits of Pinus koraiensis and Quercus mongolica to five filter treatments that differed in the spectral transmittance: (a) 95 % of solar radiation was transmitted (280–700 nm); (b) ultraviolet (UV)-B radiation was attenuated (>315 nm); (c) all UV radiation was attenuated (>400 nm); (d) all UV radiation and blue light was attenuated (>500 nm); (e) all UV radiation, blue-green light was attenuated (>580 nm). Our results showed that functional traits responded to UV-B radiation (contrasting treatment [a] vs. [b]) with species-dependence, but consistently showed a positive response to blue light (contrasting treatment [c] vs. [d]). UV-B radiation decreased the relative growth rate (RGR) and leaf area ratio (LAR) of P. koraiensis seedlings by 48 % and 42 %, respectively; however, it increased seedling height, total leaf area (TLA), and above-ground biomass of Q. mongolica. Blue light consistently increased LAR and RGR of two species. Furthermore, Q. mongolica was more plastic in morphological traits (including plant height and TLA) and root/shoot ratio than P. koraiensis to the single spectral region (UV-B, UV-A, blue, and green light), but opposite in physiological and biochemical traits (such as chlorophyll and anthocyanidin). These suggest that two studied species have evolved different light capture strategies in the understorey: Q. mongolica seedlings tended to adjust morphology and biomass allocation to enhance light interception capacity, while P. koraiensis seedlings preferred to adjust physiological and biochemical traits to enhance light utilization efficiency. A better understanding how canopy spectral compositions affect seedling regeneration may provide a new insight for future forest management (i.e. the appropriate gap creation or tree species combination).

Assessment of the Predictive Ability of Theranostics for Corneal Cross-linking in Treating Keratoconus: A Randomized Clinical Trial

PurposeTo validate the ability of theranostic imaging biomarkers in assessing the propensity of corneal cross-linking (CXL) in flattening the maximum keratometry (Kmax) index. DesignProspective, randomized, multicenter, masked clinical trial (NCT05457647). ParticipantsFifty patients with progressive keratoconus. InterventionParticipants were stratified to undergo epithelium-off (epi-off; 25 eyes) and epithelium-on (epi-on; 25 eyes) CXL protocols using UV-A medical device incorporating theranostic software module. The device used controlled UV-A light both for performing CXL and for estimating the corneal riboflavin concentration (riboflavin score) and assessing treatment effect (theranostic score) in real time. A 0.22% riboflavin formulation was applied onto the cornea for 15 minutes and 20 minutes in epi-off and epi-on protocols respectively. All eyes underwent 9 minutes UV-A irradiance at 10 mW/cm2. Main Outcome MeasuresThe primary outcome measure was validation of the combined use of theranostic imaging biomarkers through measurement of their accuracy (proportion of correctly classified eyes) and precision (positive predictive value) to correctly classify eyes and positively predict a Kmax flattening at 1 year after CXL. Other outcome measures were the change of Kmax, endothelial cell density, uncorrected and corrected distance visual acuity, manifest spherical equivalent refraction, and central corneal thickness one year after CXL. ResultsAccuracy and precision of the combined use of theranostic imaging biomarkers in predicting eyes that had more than 0.1 diopter (D) Kmax flattening at 1 year were 91% and 95% respectively. The Kmax value significantly flattened by a median of -1.3 D (IQR: -2.11, -0.49 D; P < 0.001); both the uncorrected and corrected distance visual acuity improved by a median of -0.1 LogMAR (IQR: -0.3, 0.0 LogMAR; P < 0.001 and IQR: -0.2, 0.0 LogMAR; P < 0.001 respectively). There were no significant changes in endothelial cell density (P = 0.33) and central corneal thickness (P = 0.07) 1 year postoperatively. ConclusionsThe study demonstrated the efficacy of integrating theranostics in a UV-A medical device for the precise and predictive treatment of keratoconus with epi-off and epi-on CXL protocols. The concentration of riboflavin and its UV-A light mediated photo-activation in the cornea are the primary factors determining CXL treatment efficacy.

Synthesis, Characterization, and Photocatalytic Properties of Sol-Gel Ce-TiO2 Films

In this study, nanostructured cerium-doped TiO2 (Ce-TiO2) films with the addition of different amounts of cerium (0.00, 0.08, 0.40, 0.80, 2.40, and 4.10 wt.%) were deposited on a borosilicate glass substrate by the flow coating sol-gel process. After flow coating, the deposited films were dried at a temperature of 100 °C for 1 h, followed by calcination at a temperature of 450 °C for 2 h. For the characterization of sol-gel TiO2 films, the following analytic techniques were used: X-ray diffraction (XRD), differential thermal analysis (DTA), thermal gravimetry (TG), differential scanning calorimetry (DSC), diffuse reflectance spectroscopy (DRS), and energy dispersive X-ray spectroscopy (EDS). Sol-gel-derived Ce-TiO2 films were used for photocatalytic degradation of ciprofloxacin (CIP). The influence of the amount of Ce in TiO2 films, the duration of the photocatalytic decomposition, and the irradiation type (UV-A and simulated solar light) on the CIP degradation were monitored. Kinetics parameters (reaction kinetics constants and the half-life) of the CIP degradation, as well as photocatalytic degradation efficiency, were determined. The best photocatalytic activity was achieved by the TiO2 film doped with 0.08 wt.% Ce, under both UV-A and solar irradiation. The immobilized catalyst was successfully reused for three cycles under solar light simulator radiation, with changes in photocatalytic efficiency below 3%.

60‐4: Minimal Efficiency Degradation and Elevated Radiometric Power Density of Ultraviolet‐A Micro‐LED with Homoepitaxial Structure

As display technology continues to advance, UVA micro‐LEDs are becoming increasingly important in a variety of display and beyond‐display applications. In this study, we investigate the optoelectronic characteristics of UVA micro‐LEDs based on a homogeneously epitaxial structure on freestanding gallium nitride (GaN) substrates. The device exhibits a central wavelength of 390 nm, positioned at the overlap of UVA and visible light spectra. It demonstrates an impressively low ideality factor of 1.49 at 2.86 V and a series resistance of 9.88 O beyond 3 V. Optically, our device shows virtually no wavelength shift across a wide current density range of 0.1‐1000 A/cm2, indicating exceptional optical stability and color accuracy. The emitted light is typical purple, reaching an expansive color gamut of 115.3% of Rec.2020. Furthermore, the GaN‐on‐GaN structure, with its superior crystal structure and heat dissipation properties, results in a very low droop ratio in EQE. This ensures sustained highpower output at high current densities, showcasing great potential in applications such as 3D printing, maskless photolithography, and fluorescence tagging.

Pd(II)-Porphyrin-sensitized smart star polymer photocatalysts: A light-harvesting strategy using fluorescence resonance energy transfer effects

Photochemistry has become a popular topic in the field of sustainability. In particular, photocatalysts are a promising method to deal with environmental pollution, but only a few light sources with limited wavelengths are utilized to activate photosensitizers. Herein, we broaden the range of activation wavelengths of porphyrin-core amphiphilic star polymer photocatalysts by light harvesting. The coumarin moiety was polymerized from the porphyrin core while maintaining the amphiphilic microenvironment of the star polymer. The fluorescence resonance energy transfer (FRET) between porphyrin and coumarin leads to the activation of photocatalysts under both UV-A and UV-B light. Moreover, the copolymer sequence and polymer swelling effects on the FRET efficiency are discussed. The amphiphilic star block copolymer exhibited superior energy transfer efficiency in polar solvents, and its photocatalytic activity was evaluated via 2,5-dimethylfuran (2,5-DMF) photooxidation.

Photocatalytic Degradation of Naproxen: Intermediates and Total Reaction Mechanism.

Photochemical and photocatalytic oxidation of naproxen (NPX) with UV-A light and commercial TiO2 under constant flow of oxygen have been investigated. Adsorption experiments indicated that 90% of the solute remained in the solution. Combined chemical analysis of samples on the photochemical degradation indicated that NPX in an aqueous solution (20 ppm) is efficiently transformed into other species but only 18% of the reactant is mineralized into CO2 and water after three hours of reaction. Performing the photocatalytic oxidation in the presence of TiO2, more than 80% of the organic compounds are mineralized by reactive oxidation species (ROS) within four hours of reaction. Analysis of reaction mixtures by a combination of analytical techniques indicated that naproxen is transformed into several aromatic naphthalene derivatives. These latter compounds are eventually transformed into polyhydroxylated aromatic compounds that are strongly adsorbed onto the TiO2 surface and are quickly oxidized into low-molecular-weight acids by an electron transfer mechanism. Based on this and previous studies on NPX photocatalytic oxidation, a unified and complete degradation mechanism is presented.

Synthesis and characterization of X (X = Ni or Fe) modified BaTiO3 for effective degradation of Reactive Red 120 dye under UV-A light and its biological activity

For the sustainable advancement of industrial expansion that is environmentally conscious, harmful dyes must be removed from wastewater. Untreated effluents containing colors have the potential to harm the ecosystem and pose major health risks to people, animals, and aquatic life. Here, we have fabricated Ni or Fe modified with BaTiO3 materials and effectively utilized them for Reactive Red 120 (RR 120) dye degradation under UV-A light. The synthesized materials were characterized, and their structural, and photo-physical properties were reported. Phase segregation was not present in the XRD pattern, as evidenced by the absence of secondary phase peaks linked to iron, nickel, or oxides. Low metal ion concentrations may be the cause of this, and the presence of those elements was confirmed by XPS measurements. The Raman spectra of the BaTiO3/Ni and BaTiO3/Fe samples show a widened peak at 500 cm−1, which suggests that Ni or Fe are efficiently loaded onto the BaTiO3. RR 120 dye photodegradation under UV light conditions was effectively catalyzed by BaTiO3/Fe, as evidenced by its superior performance in the UV irradiation technique over both BaTiO3 and BaTiO3/Ni. Compared to bare BaTiO3, both metal-modified materials efficiently degraded the RR 120 dye. Acidic pH facilitated the degradation process, which makes sense given that the heterogeneous photo-Fenton reaction was the mechanism of degradation along with BaTiO3 sensitization. High-acidity sewage can be dangerous and carcinogenic, and conventional biological treatment methods are not appropriate for managing it. In the current investigation, it may be used to treat color effluents with extremely low pH levels. Additionally, the ability of the produced nanocomposites to inhibit the growth of twenty pathogens was examined, along with two fungi, fifteen Gram-negative Bacilli (GNB), one Gram-positive Bacilli (GPB), and two Gram-positive Cocci (GBC).

The effect of oxidative degradation of Dopa-melanin on its basic physicochemical properties and photoreactivity.

Melanin, particularly eumelanin, is commonly viewed as an efficient antioxidant and photoprotective pigment. Nonetheless, the ability of melanin to photogenerate reactive oxygen species and sensitize the formation of cyclobutane pyrimidine dimers may contribute to melanin-dependent phototoxicity. The phototoxic potential of melanin depends on a variety of factors, including molecular composition, redox state, and degree of aggregation. Using complementary spectroscopic and analytical methods we analyzed the physicochemical properties of Dopa-melanin, a synthetic model of eumelanin, subjected to oxidative degradation induced by aerobic photolysis or exposure to 0.1 M hydrogen peroxide. Both modes of oxidative degradation were accompanied by dose-dependent bleaching of melanin and irreversible modifications of its paramagnetic, ion- and electron-exchange and antioxidant properties. Bleached melanin exhibited enhanced efficiency to photogenerate singlet oxygen in both UVA and short-wavelength visible light. Although chemical changes of melanin subunits, including a relative increase of DHICA content and disruption of melanin polymer induced by oxidative degradation were considered, these two mechanisms may not be sufficient for a satisfactory explanation of the elevated photosensitizing ability of the bleached eumelanin. This study points out possible adverse changes in the photoprotective and antioxidant properties of eumelanin that could occur in pigmented tissues after exposure to high doses of intense solar radiation.

Synergistic effect of light in piezocatalytic activation of peroxymonosulfate using graphtic carbon nitride nanosheets for degradation of organic pollutants

The objective of the study was to understand the photo-piezocatalytic response of graphitic carbon nitride nanosheets (CNNS) for the activation of peroxymonosulfate (PMS). Methylene blue (MB) dye was targeted by PMS activation using CNNS under ultrasonic-assisted piezocatalysis and photo-piezocatalysis in a batch reactor for 120 min. CNNS has shown 98.4% MB removal within 120 min in a batch study (PMS = 200 mg L-1, CNNS = 1 g L-1, ultrasonicator = 40 kHz, UV-A light = 250 W). CNNS (0.0157 min-1) showed 1.3 times higher photo-piezocatalytic activity compared to bulk graphitic carbon nitride (CNB) for PMS activation due to improvement in in-plane polarization. In the photo-piezocatalytic CNNS/PMS/MB system, a scavenging study revealed that the primary contributors for MB removal were hydroxyl radical (.OH) and sulfate radical (SO4.-). The piezoelectric effect combined with light at CNNS improved the excitation of charge carriers, followed by charge carrier separation due to band tilting. Finally, the effects of CNNS dose, PMS dose, and competitive anions were studied for MB removal using CNNS under photo-piezocatalysis. Overall, CNNS is a promising photo-piezocatalyst for the removal of emerging organic pollutants through PMS activation.

Modulation of the photobehavior of gefitinib and its phenolic metabolites by human transport proteins.

The photobiological damage that certain drugs or their metabolites can photosensitize in proteins is generally associated with the nature of the excited species that are generated upon interaction with UVA light. In this regard, the photoinduced damage of the anticancer drug gefitinib (GFT) and its two main photoactive metabolites GFT-M1 and GFT-M2 in cellular milieu was recently investigated. With this background, the photophysical properties of both the drug and its metabolites have now been studied in the presence of the two main transport proteins of human plasma, i.e., serum albumin (HSA) and α1-acid glycoprotein (HAG) upon UVA light excitation. In general, the observed photobehavior was strongly affected by the confined environment provided by the protein. Thus, GFT-M1 (which exhibits the highest phototoxicity) showed the highest fluorescence yield arising from long-lived HSA-bound phenolate-like excited species. Conversely, locally excited (LE) states were formed within HAG, resulting in lower fluorescence yields. The reserve was true for GFT-M2, which despite being also a phenol, led mainly to formation of LE states within HSA, and phenolate-like species (with a minor contribution of LE) inside HAG. Finally, the parent drug GFT, which is known to form LE states within HSA, exhibited a parallel behavior in the two proteins. In addition, determination of the association constants by both absorption and emission spectroscopy revealed that the two metabolites bind stronger to HSA than the parent drug, whereas smaller differences were observed for HAG. This was further confirmed by studying the competing interactions between GFT or its metabolites with the two proteins using fluorescence measurements. These above experimental findings were satisfactorily correlated with the results obtained by means of molecular dynamics (MD) simulations, which revealed the high affinity binding sites, the strength of interactions and the involved amino acid residues. In general, the differences observed in the photobehavior of the drug and its two photoactive metabolites in protein media are consistent with their relative photosensitizing potentials.

Novel nanohybrid iron (II/III) phthalocyanine-based carbon nanotubes as catalysts for organic pollutant removal: process optimization by chemometric approach.

In the present study, two iron phthalocyanine (FePc)-based nanocatalysts were synthesized and fully characterized. The carbon nanotubes (CNT) functionalized in an easy way with either Fe(II)Pc or Fe(III)Pc exhibit a very good catalytical activity. The activity in real wastewater effluent was comparable with the activity in distilled water. The procedure of modeling and optimizing with the assistance of chemometrics, utilizing design of experiments (DOE) and response surface methodology (RSM), revealed the conditions of optimum for decaying Reactive Yellow 84 on the nanocatalysts FePc_CNT. These optimal conditions included a catalyst dose of 1.70 g/L and an initial concentration (C0) of 20.0 mg/L. Under the indicated optimal conditions, the experimental findings verified that the removal efficiency was equal to Y = 98.92%, representing the highest observed value in this study. Under UVA light, after only 15 min of reaction, over 94% of dye was removed using both catalysts. The reuse experiments show that the activity of both nanohybrid material based on FePc-CNT slightly decreases over four consecutive runs. The quenching experiments show that RY84 was removed through radical pathways (O2•- and •OH) as well as non-radical pathways (1O2 and direct electron transfer).

Photocatalytic Activity and Antibacterial Properties of Mixed-Phase Oxides on Titanium Implant Alloy Substrates

Titanium alloys are commonly used for implants, but the naturally forming oxides are bioinert and not ideal for bacterial resistance or osseointegration. Anodization processes are a modification technique that can crystallize the oxides, alter oxide surface topography, and introduce beneficial chemistries. Crystalline titanium oxides are known to exhibit photocatalytic activity (PCA) under UVA light. Anodization was used to create mixed-phase oxides on six titanium alloys including commercially pure titanium (CPTi), Ti-6Al-4V (TAV), Ti-6Al-7Nb (TAN), two forms of Ti-15Mo (TiMo-β and TiMo-αβ), and Ti-35Nb-7Zr-5Ta (TNZT). Combined EDS and XPS analyses showed uptake of the electrolyte and substrate alloying elements into the oxides. The relative oxide PCA was measured using methylene blue degradation assays. CPTi and TAN oxides exhibited increased PCA compared to other alloys. Combined XRD and EBSD oxide phase analyses revealed an unfavorable arrangement of anatase and rutile phases near the outermost surfaces, which may have reduced PCA for other oxides. The relative Staphylococcus aureus attachment to each oxide was also assessed. The CPTi and TiMo-αβ oxides showed significantly reduced S. aureus attachment after 1 h of UVA compared to un-anodized CPTi. Cell culture results verified that the UVA irradiation did not negatively influence the MC3T3-E1 attachment or proliferation on the mixed-phase oxides.

Vitiligo Causes and Treatment: A Review

Vitiligo is a chronic autoimmune disorder characterized by patches of skin losing pigment due to the destruction of melanocytes, the cells responsible for producing pigment. The condition can affect people of all ages and ethnicities, with symptoms including milky-white patches on the skin, premature graying of hair, and color loss in mucous membranes like the mouth or nose. Among the main causes of vitiligo are; Autoimmune Response: Vitiligo is primarily an autoimmune disease where the immune system mistakenly attacks melanocytes, leading to depigmentation. Factors like family history, genetic predisposition, and immune system disorders contribute to its development, Triggers: Events such as sunburn, emotional distress, or exposure to certain chemicals can trigger or exacerbate vitiligo. The treatment options are; Medications: Treatments include light therapy (phototherapy), oral medications like psoralen combined with UVA light (PUVA), and depigmentation therapy using monobenzone to match skin tones Surgery: Surgical options are available for some cases of vitiligo and Psychological Support: Counseling and mental health services can help individuals cope with the emotional impact of vitiligo, in conclusion, v is a multifaceted skin condition lacking a conclusive remedy, many types of vitiligo, but the most common one is Non-segmental Vitiligo (NSV), honmental and genetic are the most important causes of vitiligo. Important symptoms of vitiligo are; depigmented patches, hair discoloration, sensitivity to sunlight, treatment of vitiligo have many approach, among them are; topical Corticosteroids, phototherapy and Cosmetic Camouflage.

Functionalizing DNA Origami by Triplex-Directed Site-Specific Photo-Cross-Linking.

Here, we present a cross-linking approach to covalently functionalize and stabilize DNA origami structures in a one-pot reaction. Our strategy involves adding nucleotide sequences to adjacent staple strands, so that, upon assembly of the origami structure, the extensions form short hairpin duplexes targetable by psoralen-labeled triplex-forming oligonucleotides bearing other functional groups (pso-TFOs). Subsequent irradiation with UVA light generates psoralen adducts with one or both hairpin staples leading to site-specific attachment of the pso-TFO (and attached group) to the origami with ca. 80% efficiency. Bis-adduct formation between strands in proximal hairpins further tethers the TFO to the structure and generates "superstaples" that improve the structural integrity of the functionalized complex. We show that directing cross-linking to regions outside of the origami core dramatically reduces sensitivity of the structures to thermal denaturation and disassembly by T7 RNA polymerase. We also show that the underlying duplex regions of the origami core are digested by DNase I and thus remain accessible to read-out by DNA-binding proteins. Our strategy is scalable and cost-effective, as it works with existing DNA origami structures, does not require scaffold redesign, and can be achieved with just one psoralen-modified oligonucleotide.

Spatial targeted delivery of riboflavin with a controlled corneal iontophoresis delivery system in theranostic-guided UV-A light photo-therapy.

Seven human donor eye globes underwent corneal cross-linking using theranostic UV-A device with accessory corneal iontophoresis system for patterned delivery of a 0.22% riboflavin solution. Theranostic-guided UV-A light illumination assessed riboflavin distribution and treated corneas at 10 mW/cm2 for 9 min with a 5.0-mm beam size. Corneal topography maps were taken at baseline and 2-h post-treatment. Analysis utilized corneal topography elevation data, with results showing controlled riboflavin delivery led to a consistent gradient, with 40% higher levels centrally (248 ± 79 μg/cm3) than peripherally (180 ± 72 μg/cm3 at ±2.5 mm from the center). Theranostic-guided UV-A light irradiation resulted in significant changes in corneal topography, with a decrease in best-fit sphere value (-0.7 ± 0.2 D; p < 0.001) and consistent downward shift in corneal elevation map (-11.7 ± 3.7 μm). The coefficient of variation was 2.5%, indicating high procedure performance in achieving significant and reliable corneal flattening.

Improved perovskite photostability via application of TiO2, ZnO and AZO thin films by pulsed laser deposition

The UV-induced degradation of perovskite solar cells has been a barrier to commercialization. Thin film encapsulation represents a promising solution for extending perovskite solar cell lifetimes. Three materials with suitable bandgaps for blocking UV light are identified: TiO2, ZnO and AZO. Herein, the optical properties of TiO2, ZnO and AZO thin films grown by pulsed laser deposition at room-temperature are optimized by varying the oxygen partial pressure between 2, 5 and 20 mTorr during deposition. UV–Vis spectroscopy reveals facile bandgap tuning via the PLD O2 pressure for maximized UV light absorption/reflection. In particular, the TiO2 bandgap is found to narrow with decreasing O2 partial pressure as a result of an increase in oxygen vacancies and Ti3+ interstitials. Conversely, the AZO bandgap widens with decreasing O2 partial pressure, as explained by the Burstein-Moss effect. Finally, ZnO films have stable optical properties at all investigated oxygen pressures. The analysis finds that ZnO, TiO2, and AZO coatings exhibit maximum percentages of absorbed/reflected UV-A light of 72.13 ± 3.05%, 52.30 ± 2.72%, and 52.06 ± 2.20% at 5, 2 and 20 mTorr O2, respectively. Accelerated UV-aging experiments find that the films which screen the most UV light are also most effective in delaying perovskite degradation. A comparison of TiO2, ZnO and AZO photoprotective coatings concludes that ZnO is most suitable for perovskite solar cell encapsulation since it provides a ∼ 50% reduction in UV-degradation without significantly compromising visible light transmittance.

Photoactivated riboflavin inhibits planktonic and biofilm growth of Candida albicans and non-albicans Candida species

Fungal infections caused by Candida species pose a serious threat to humankind. Antibiotics abuse and the ability of Candida species to form biofilm have escalated the emergence of drug resistance in clinical settings and hence, rendered it more difficult to treat Candida-related diseases. Lethal effects of Candida infection are often due to inefficacy of antimicrobial treatments and failure of host immune response to clear infections. Previous studies have shown that a combination of riboflavin with UVA (riboflavin/UVA) light demonstrate candidacidal activity albeit its mechanism of actions remain elusive. Thus, this study sought to investigate antifungal and antibiofilm properties by combining riboflavin with UVA against Candida albicans and non-albicans Candida species. The MIC20 for the fluconazole and riboflavin/UVA against the Candida species tested was within the range of 0.125–2 μg/mL while the SMIC50 was 32 μg/mL. Present findings indicate that the inhibitory activities exerted by riboflavin/UVA towards planktonic cells are slightly less effective as compared to controls. However, the efficacy of the combination towards Candida species biofilms showed otherwise. Inhibitory effects exerted by riboflavin/UVA towards most of the tested Candida species biofilms points towards a variation in mode of action that could make it an ideal alternative therapeutic for biofilm-related infections.