Light-Triggered Adhesive Silk-Based Film for Effective Photodynamic Antibacterial Therapy and Rapid Hemostasis

Successful control of massive hemorrhage in deep wounds with irregular shape and low elasticity still remains great challenges in the clinic. As the wound sites are usually at risk of bacterial infection, it is necessary to design an ideal hemostatic agent with rapid hemostasis and excellent antibacterial activity. In this study, we developed a light responsive hemostatic film for effective handling of liver bleeding with promising photodynamic therapy against S. aureus onnear infrared (NIR) irradiation. Based on silk fibroin, the film exhibited desirable biocompatibility and mechanical property as a hemostat tape. Significantly, the film tape achieved excellent tissue adhesion and hemostasis in vivo within 2 min of UV exposure, which would have a great potential as a multifunctional biomedical material in the field of tissue repair such as wound healing, bone repair, and nerve regeneration.

Evaluation of parameters governing dark and photorepair in UVC-irradiated Escherichia coli

After decades of UV disinfection practice and numerous studies on the potential for pathogens to undergo dark or photo-repair after UV exposure, recent advances in UV light emitting diode (LED)...

Molecular docking of lutein as anti-photoaging agent in silico

The accumulation of UV exposure resulted in the loss of skin elasticity, and the appearance of wrinkles on the skin is commonly known as photoaging. Matrix metalloproteinase-1 (MMP-1) is an enzyme that degrades type I and III fibrillar collagen. This study aims to determine the mechanism of MMP-1 inhibition by lutein, a carotenoid compound with high antioxidant activity, using in silico molecular docking. This study was conducted by optimization of lutein structure using HyperChem 8, preparation of MMP-1 (PDB ID: 966C) using Chimera 1.10.1, validation of the method, and docking lutein against MMP-1 using Autodock 4.2. The results showed lutein had binding energy of -12.28 kcal/mol, lower than RS2 native ligand (-10.83 kcal/mol). The hydrogen bond formed between lutein and MMP-1 through HIS228 residue. To conclude, lutein may be developed as an anti-photoaging agent by inhibiting the MMP-1.

Rapid Prototyping of Organ-on-a-Chip Devices Using Maskless Photolithography

Organ-on-a-chip (OoC) and microfluidic devices are conventionally produced using microfabrication procedures that require cleanrooms, silicon wafers, and photomasks. The prototyping stage often requires multiple iterations of design steps. A simplified prototyping process could therefore offer major advantages. Here, we describe a rapid and cleanroom-free microfabrication method using maskless photolithography. The approach utilizes a commercial digital micromirror device (DMD)-based setup using 375 nm UV light for backside exposure of an epoxy-based negative photoresist (SU-8) on glass coverslips. We show that microstructures of various geometries and dimensions, microgrooves, and microchannels of different heights can be fabricated. New SU-8 molds and soft lithography-based polydimethylsiloxane (PDMS) chips can thus be produced within hours. We further show that backside UV exposure and grayscale photolithography allow structures of different heights or structures with height gradients to be developed using a single-step fabrication process. Using this approach: (1) digital photomasks can be designed, projected, and quickly adjusted if needed; and (2) SU-8 molds can be fabricated without cleanroom availability, which in turn (3) reduces microfabrication time and costs and (4) expedites prototyping of new OoC devices.

Enhanced Production of Citric Acid by Mutant PN12 of Aspergillus fumigatus Using Statistical Design

Distillery spent wash is an unwanted residual liquid waste generated during alcohol production. It is a potential source for production of different industrially important products. Distillery spent wash is dark colored and has many organic compounds as a waste. In this experiment, removal of color and organic compounds was carried out by anaerobic treatment. The treated spent wash was utilized for citric acid production with the help of microorganisms. The current study was performed with the treated spent wash which was applied for high level of citric acid production by a mutant strain of Aspergillus fumigatus PN12. The parent strain Aspergillus fumigatus PN12 was mutagenized by UV exposure to enhance citric acid production. After UV exposure investigation, mutant strain was selected for optimization and statistical method. The best citric acid production obtained was, 26.45 g/L at 30 ℃ with pH 6.0, 0.1 g/L of KH2PO4 and (NH4)2SO4 under OFAT. Under RSM optimization, maximum citric acid production was achieved as 30.89 g/L. Thus, the process optimization through the statistical approach resulted in a 1.16-fold enhancement in citric acid production as compared to that of the OFAT parametric conditions. Citric acid producing enzymes such as aconitase, NAD+-isocitrate dehydrogenase and NADP+ isocitrate dehydrogenase was studied. Maximum activity (U/mg) of aconitase (3.19±0.023), NAD+-isocitrate dehydrogenase (3.0±0.15) and NADP+ isocitrate dehydrogenase (2.91±0.17) was observed at 96 h. The present study can conclude that spent wash is potential source for citric acid production. Utilization of mutant strain of Aspergillus fumigatus PN12 is beneficiary for large scale industrial fermentation and citric acid production.

Selection for and Analysis of UV-Resistant Cryptophlebia Leucotreta Granulovirus-SA as a Biopesticide for Thaumatotibia leucotreta

Cryptophlebia leucotreta granulovirus-SA (CrleGV-SA) is used as a commercial biopesticide for the false codling moth, Thaumatotibia leucotreta, in citrus and other crops. The virus is sensitive to UV irradiation from sunlight, which reduces its efficacy as a biopesticide in the field. We selected a UV-resistant CrleGV-SA isolate, with more than a thousand-fold improved virulence compared to the wild-type isolate, measured by comparing LC50 values. CrleGV-SA purified from infected T. leucotreta larvae was exposed to UV irradiation under controlled laboratory conditions in a climate chamber mimicking field conditions. Five cycles of UV exposure, followed by propagating the virus that retained infectivity in vivo with re-exposure to UV, were conducted to isolate and select for UV-resistant virus. Serial dilution bioassays were conducted against neonates after each UV exposure cycle. The concentration-responses of the infectious UV-exposed virus populations were compared by probit analysis with those from previous cycles and from the original CrleGV-SA virus population. NGS sequences of CrleGV-SA samples from UV exposure cycle 1 and cycle 5 were compared with the GenBank CrleGV-SA sequence. Changes in the genomes of infective virus from cycles 1 and 5 generated SNPs thought to be responsible for establishing UV tolerance. Additional SNPs, detected only in the cycle 5 sequence, may enhance UV tolerance and improve the virulence of the UV-tolerant population.

Experimental Investigations of AlMg3 Components with Polyurethane and Graphene Oxide Nanosheets Composite Coatings, after Accelerated UV-Aging

The use of graphene (Gr) and its derivates graphene oxide (GO) showed that these materials are good candidates to enhance the properties of polyurethane (PU) coatings, especially the anticorrosion ones since graphene absorbs most of the light and provides hydrophobicity for repelling water. An important aspect of these multifunctional materials is that all these improvements can be realized even at very low filler loadings in the polymer matrix. In this work, an ultrasound cavitation technique was used for the proper dispersion of GO nanosheets (GON) in polyurethane (PU) resin to obtain a composite coating to protect the AlMg3 substrate. The addition of GON considerably improved the physical properties of coatings, as demonstrated by electrochemical impedance spectroscopy (EIS) analysis, promising improved anticorrosion performance after accelerated UV-ageing. Computational methods and Differential Scanning Calorimetry (DSC) measurements showed that GON facilitates the formation of additional bonds and stabilizes the PU structures during the ultraviolet (UV) exposure and aggressive attack of corrosive species. Limiting oxygen index (LOI) data reveal a slow burning behaviour of PU-GON coatings during UV exposure, which is better than PU alone.

Evaluating efficacy of different UV-stabilizers/absorbers in reducing UV-degradation of lignin

Susceptibility of wood to UV degradation decreases the service life of wood products outdoors. Organic UV absorbers (UVAs) and hindered amine light stabilizers (HALSs), as well as inorganic UVAs, are added to coatings to improve the UV stability of coated-wood products. Although about 85% of UV radiation is absorbed by lignin in the wood, it is unclear which UV stabilizers can minimize lignin degradation. In this study, the photodegradation of softwood organosolv lignin was monitored over 35 days of UV exposure. Changes in lignin properties were assessed using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and phosphorus-31 nuclear magnetic resonance spectroscopy (31P NMR). It was found that the aromatic rings of lignin underwent significant degradation, resulting in increased glass transition temperature and molecular weight of lignin. Subsequently, 18 different additives were mixed with lignin and exposed to UV irradiation. The analysis of samples before and after UV exposure with FTIR revealed that inorganic UVAs (cerium oxide and zinc oxide) and a mixture of organic UVAs and HALSs (T-479/T-292, T-5248, and T-5333) were the most effective additives in reducing lignin degradation. This study can help coating scientists to formulate more durable transparent exterior wood coatings.

Correction: Lamy et al. Monitoring Solar Radiation UV Exposure in the Comoros. Int. J. Environ. Res. Public Health 2021, 18, 10475

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The Effect of UV Exposure on the Service-life of Thermochromic Microcapsules Integrated into the Epoxy Matrix

The effect of ultraviolet (UV) exposure on the service-life of thermochromic microcapsules integrated into the epoxy matrix was investigated. The microcapsules of the formaldehyde shell contain the core of thermochromic leuco dye. Seven sets of epoxy resin samples filled with concentrations from 0 to 10 wt.% of microcapsules were investigated. The composite samples were exposed to UV for approximately 1000 h. For the quantitative evaluation of colour change under UV, a fast and simple original procedure based on samples’ image treatment was developed. With the exposure time intervals of 50 h, samples were taken out from the UV light chamber to evaluate the exposure effect on their reversible thermochromic ability and mechanical properties. Periodical evaluation of the UV light effect on mechanical properties during the exposure was performed by microhardness tests. Tensile tests of the samples till the fracture were performed every 200 h. The critical time under the exposure of the UV lamp that destroys the reversible thermochromic reaction of the microcapsules was defined as 200 h. At the same time, it has been found that the mechanical properties of the epoxy resin under the same UV source were not strongly affected after 1000 h of irradiance and changed in the frame of ~ 10 %.