Emerging potentials of Fe-based nanomaterials for chiral sensing and imaging.

Fe-based nanostructures have possessed promising properties that make it suitable for chiral sensing and imaging applications owing to their ultra-small size, non-toxicity, biocompatibility, excellent photostability, tunable fluorescence, and water solubility. This review summarizes the recent research progress in the field of Fe-based nanostructures and places special emphases on their applications in chiral sensing and imaging. The synthetic strategies to prepare the targeted Fe-based structures were also introduced. The chiral sensing and imaging applications of the nanostructures are discussed in details.

Rugged Forest Morphology of Magnetoplasmonic Nanorods that Collect Maximum Light for Photoelectrochemical Water Splitting.

A feasible nanoscale framework of heterogeneous plasmonic materials and proper surface engineering can enhance photoelectrochemical (PEC) water-splitting performance owing to increased light absorbance, efficient bulk carrier transport, and interfacial charge transfer. This article introduces a new magnetoplasmonic (MagPlas) Ni-doped Au@Fex Oy nanorods (NRs) based material as a novel photoanode for PEC water-splitting. A two stage procedure produces core-shell Ni/Au@Fex Oy MagPlas NRs. The first-step is a one-pot solvothermal synthesis of Au@Fex Oy . The hollow Fex Oy nanotubes (NTs) are a hybrid of Fe2 O3 and Fe3 O4 , and the second-step is a sequential hydrothermal treatment for Ni doping. Then, a transverse magnetic field-induced assembly is adopted to decorate Ni/Au@Fex Oy on FTO glass to be an artificially roughened morphologic surface called a rugged forest, allowing more light absorption and active electrochemical sites. Then, to characterize its optical and surface properties, COMSOL Multiphysics simulations are carried out. The core-shell Ni/Au@Fex Oy MagPlas NRs increase photoanode interface charge transfer to 2.73 mAcm-2 at 1.23 V RHE. This improvement is made possible by the rugged morphology of the NRs, which provide more active sites and oxygen vacancies as the hole transfer medium. The recent finding may provide light on plasmonic photocatalytic hybrids and surface morphology for effective PEC photoanodes.

Effective inactivation of Bacillus atrophaeus spores and Escherichia coli on disposable face masks using ultraviolet laser irradiation.

Due to the widespread emergence of COVID-19, face masks have become a common tool for reducing transmission risk between people, increasing the need for sterilization methods against mask-contaminated microorganisms. In this study, we measured the efficacy of ultraviolet (UV) laser irradiation (266 nm) as a sterilization technique against Bacillus atrophaeus spores and Escherichia coli on three different types of face mask. The UV laser source demonstrated high penetration of inner mask layers, inactivating microorganisms in a short time while maintaining the particle filtration efficiency of the masks. This study demonstrates that UV laser irradiation is an efficient sterilization method for removing pathogens from face masks.

One-Pot Synthesis of Magnetoplasmonic Au@FexOy Nanowires: Bioinspired Bouligand Chiral Stack.

One-dimensional hybrid nanostructures composed of a plasmonic gold nanowire core covered by a shell of magnetic oxide nanoparticles (Au@FexOy NWs) were synthesized by a one-pot solvothermal synthesis process. The effects of reaction temperature, time, reducing agent, and precursor as well as postsynthesis treatment were optimized to produce highly uniform NWs with a diameter of 226 ± 25 nm and a plasmonic core aspect ratio of 25 to 82. By exploiting the interaction of NWs with an external magnetic field, precise arrangements into highly periodic photonic structures were achieved, which can generate distinctive structural colors that are vividly iridescent and polarization-sensitive. Furthermore, a Bouligand-type chiral nematic film consisting of multistacked unidirectional layers of achiral NWs was fabricated using a modified layer-by-layer deposition method, which displays circular dichroism (CD) and chiral sensing capability. The addition of bovine serum albumin (BSA) as a model protein analyte induced a concentration-dependent wavelength shift of CD peaks. These intriguing properties of magnetoplasmonic anisotropic NWs and their self-assemblies could be consequently valuable for developing nature-inspired structural color imprints as well as solid-state chiral sensing devices.

Sterilization effects of UV laser irradiation on Bacillus atrophaeus spore viability, structure, and proteins.

Bacillus spores are highly resistant to toxic chemicals and extreme environments. Because some Bacillus species threaten public health, spore inactivation techniques have been intensively investigated. We exposed Bacillus atrophaeus spores to a 266 nm Nd:YVO4 laser at a laser power of 1 W and various numbers of scans. As a result, the UV laser reduced the viability of Bacillus atrophaeus spores. Although the outer coat of spores remained intact after UV laser irradiation of 720 scans, damage inside the spores was observed. Spore proteins were identified by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry during the course of UV laser irradiation. Photochemical and photothermal processes are believed to be involved in the UV laser sterilization of Bacillus spores. Our findings suggest that a UV laser is capable of sterilizing Bacillus atrophaeus spores.

Amyloid-like ribbons of amelogenins in enamel mineralization.

Enamel, the outermost layer of teeth, is an acellular mineralized tissue that cannot regenerate; the mature tissue is composed of high aspect ratio apatite nanocrystals organized into rods and inter-rod regions. Amelogenin constitutes 90% of the protein matrix in developing enamel and plays a central role in guiding the hierarchical organization of apatite crystals observed in mature enamel. To date, a convincing link between amelogenin supramolecular structures and mature enamel has yet to be described, in part because the protein matrix is degraded during tissue maturation. Here we show compelling evidence that amelogenin self-assembles into an amyloid-like structure in vitro and in vivo. We show that enamel matrices stain positive for amyloids and we identify a specific region within amelogenin that self-assembles into ß-sheets. We propose that amelogenin nanoribbons template the growth of apatite mineral in human enamel. This is a paradigm shift from the current model of enamel development.

Structural Insights into Anthranilate Priming during Type II Polyketide Biosynthesis.

The incorporation of nonacetate starter units during type II polyketide biosynthesis helps diversify natural products. Currently, there are few enzymatic strategies for the incorporation of nonacetate starter units in type II polyketide synthase (PKS) pathways. Here we report the crystal structure of AuaEII, the anthranilate:CoA ligase responsible for the generation of anthraniloyl-CoA, which is used as a starter unit by a type II PKS in aurachin biosynthesis. We present structural and protein sequence comparisons to other aryl:CoA ligases. We also compare the AuaEII crystal structure to a model of a CoA ligase homologue, AuaE, which is present in the same gene cluster. AuaE is predicted to have the same fold as AuaEII, but instead of CoA ligation, AuaE catalyzes acyl transfer of anthranilate from anthraniloyl-CoA to the acyl carrier protein (ACP). Together, this work provides insight into the molecular basis for starter unit selection of anthranilate in type II PKS biosynthesis.

Structural and functional analysis of two di-domain aromatase/cyclases from type II polyketide synthases.

Aromatic polyketides make up a large class of natural products with diverse bioactivity. During biosynthesis, linear poly-ß-ketone intermediates are regiospecifically cyclized, yielding molecules with defined cyclization patterns that are crucial for polyketide bioactivity. The aromatase/cyclases (ARO/CYCs) are responsible for regiospecific cyclization of bacterial polyketides. The two most common cyclization patterns are C7-C12 and C9-C14 cyclizations. We have previously characterized three monodomain ARO/CYCs: ZhuI, TcmN, and WhiE. The last remaining uncharacterized class of ARO/CYCs is the di-domain ARO/CYCs, which catalyze C7-C12 cyclization and/or aromatization. Di-domain ARO/CYCs can further be separated into two subclasses: "nonreducing" ARO/CYCs, which act on nonreduced poly-ß-ketones, and "reducing" ARO/CYCs, which act on cyclized C9 reduced poly-ß-ketones. For years, the functional role of each domain in cyclization and aromatization for di-domain ARO/CYCs has remained a mystery. Here we present what is to our knowledge the first structural and functional analysis, along with an in-depth comparison, of the nonreducing (StfQ) and reducing (BexL) di-domain ARO/CYCs. This work completes the structural and functional characterization of mono- and di-domain ARO/CYCs in bacterial type II polyketide synthases and lays the groundwork for engineered biosynthesis of new bioactive polyketides.

Characterizing workplace exposures in Vietnamese women working in California nail salons.

OBJECTIVES: We engaged Vietnamese nail salon workers in a community-based participatory research (CBPR) study to measure personal and area concentrations of solvents in their workplace. METHODS: We measured average work-shift concentrations of toluene, ethyl acetate, and isopropyl acetate among 80 workers from 20 salons using personal air monitors. We also collected area samples from 3 salons using summa canisters. RESULTS: For personal measurements, the arithmetic mean was 0.53 parts per million (range = 0.02-5.50) for ethyl acetate, 0.04 parts per million (range = 0.02-0.15) for isopropyl acetate, and 0.15 parts per million (range = 0.02-1.0) for toluene. Area measurements were lower in comparison, but we detected notable levels of methyl methacrylate, a compound long banned from nail products. Predictors of solvent levels included different forms of ventilation and whether the salon was located in an enclosed building. CONCLUSIONS: Using a CBPR approach that engaged community members in the research process contributed to the successful recruitment of salon workers. Measured levels of toluene, methyl methacrylate, and total volatile organic compounds were higher than recommended guidelines to prevent health symptoms such as headaches, irritations, and breathing problems, which were frequently reported in this workforce.

Thymosin beta4 promotes matrix metalloproteinase expression during wound repair.

Immobilized patients, diabetics, and the elderly suffer from impaired wound healing. The 43-amino acid angiogenic peptide thymosin beta4 (Tbeta4) has previously been found to accelerate dermal wound repair in rats, aged mice, and db/db diabetic mice. It also promotes corneal repair in both normal rats and mice. Because proteinases are important in wound repair, we hypothesized that Tbeta4 may regulate matrix metalloproteinase (MMP) expression in cells that are involved in wound repair. Analysis by RT-PCR of whole excised mouse dermal wounds on days 1, 2, and 3 after wounding showed that Tbeta4 increased several metalloproteinases, including MMP-2 and -9 expression by several-fold over control on day 2 after wounding. We further analyzed the metalloproteinases secreted in response to exogenous Tbeta4 by cells normally present in the wound. Western blot analysis of cultured keratinocytes, endothelial cells, and fibroblasts that were treated with increasing concentrations of Tbeta4 showed increases in the levels of MMP-1, -2, and -9 in a cell-specific manner. Tbeta4 also enhanced the secretion of MMP-1 and MMP-9 by activated monocytes. The central actin-binding domain, amino acids 17-23, had all of the activity for metalloproteinase induction. We conclude that part of the wound healing activity of Tbeta4 resides in its ability to increase proteinase activity via its central actin-binding domain. Thus, Tbeta4 may play a pivotal role in extracellular matrix remodeling during wound repair.

Thymosin beta4 increases hair growth by activation of hair follicle stem cells.

Thymosin beta4, a 43-amino acid polypeptide that is an important mediator of cell migration and differentiation, also promotes angiogenesis and wound healing. Here, we report that thymosin beta4 stimulates hair growth in normal rats and mice. A specific subset of hair follicular keratinocytes in mouse skin expresses thymosin beta4 in a highly coordinated manner during the hair growth cycle. These keratinocytes originate in the hair follicle bulge region, a niche for skin stem cells. Rat vibrissa follicle clonogenic keratinocytes, closely related, if not identical, to the bulge-residing stem cells, were isolated and their migration and differentiation increased in the presence of nanomolar concentrations of thymosin beta4. Expression and secretion of the extracellular matrix-degrading enzyme matrix metalloproteinase-2 were increased by thymosin beta4. Thus, thymosin beta4 accelerates hair growth, in part, due to its effect on critical events in the active phase of the hair follicle cycle, including promoting the migration of stem cells and their immediate progeny to the base of the follicle, differentiation, and extracellular matrix remodeling.

Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice.

Impaired wound healing is a problem for immobilized patients, diabetics, and the elderly. Thymosin beta 4 has previously been found to promote dermal and corneal repair in normal rats. Here we report that thymosin beta 4 was also active in accelerating wound repair in full-thickness dermal wounds in both db/db diabetic and aged mice. We found that thymosin beta 4 in either phosphate-buffered saline or a hydrogel formulation is active in promoting dermal wound repair in normal rats. In diabetic mice, where healing is delayed, we found that wound contracture and collagen deposition were significantly increased in the mice treated with thymosin beta 4 in either phosphate buffered saline solution or a hydrogel formulation. No difference was observed in keratinocyte migration, with all of the diabetic animals showing almost complete coverage of the wound at 8 days. Wound healing in 26-month-old (aged) animals was significantly delayed. Thymosin beta 4 accelerated wound healing in these aged mice, with increases in keratinocyte migration, wound contracture, and collagen deposition. The hydrogel formulation generally showed similar wound healing activity with thymosin beta 4 in PBS. The actin-binding domain of thymosin beta 4 duplicated in a seven-amino acid synthetic peptide, LKKTETQ, was able to promote repair in the aged animals comparable to that observed with the parent molecule. These studies show that thymosin beta 4 is active for wound repair in models of impaired healing and may have efficacy in chronic wounds in humans.