Glass Microfiber Filter Research Articles

Well water sources simultaneous contamination with Cryptosporidium and Acanthamoeba in East-Southeast Asia and Acanthamoeba spp. in biofilms in the Philippines.

Cryptosporidium is the leading agent of waterborne parasitic protozoan outbreaks and is the second leading cause of infant mortality due to diarrhoea worldwide. Acanthamoeba spp. causes Acanthamoeba keratitis (AK) and a life-threatening condition known as granulomatous amoebic encephalitis (GAE). The present study aimed to assess the water quality of an indigenous and a rural community for waterborne parasitic protozoan contamination. Aquatic samples (n = 22) were processed by filtration of 500 mL portion through a 1.2 μm pore size glass microfiber filter and eluted for light microscopy, culture in non-nutrient agar, and PCR analysis. Overall, 36% (8/22) of the investigated aquatic samples were positive for either Cryptosporidium spp. oocysts (13%; 3/22) or Acanthamoeba spp., (36%; 8/22) or both (13%; 3/22). Cryptosporidium spp. oocysts were detected in 27% (3/11) of wet season samples only while Acanthamoeba spp. were detected in 18% (2/11) and 55% (6/11) of wet and dry season samples, respectively. Subsequently, molecular detection for Acanthamoeba species identified A. lenticulata and A. hatchetti with 98-99% BLAST similarity. This is the first report on the simultaneous contamination of Cryptosporidium and Acanthamoeba in well water sources in East-Southeast Asia, the first detection of Acanthamoeba spp. in biofilms in the Philippines, and the longest viability demonstrated for A. lenticulata in two-year-old water samples stored at room temperature.

Filter paper-based colorimetric analysis: An instrument-free strategy for semiquantitative naked-eye detection of food colorants

A filter paper-based colorimetric strategy for instrument-independent visual detection of artificial food colorants (FCs) was developed in this study. Indicator papers were prepared via the one-step polycondensation of silane coupling agents onto glass microfiber filter papers, and colorimetric cards with a fine one-to-one correspondence between their colors and FCs concentrations were straightforward obtained by the extraction of FCs with indicator papers by virtue of electrostatic interaction and hydrophobic effect. Filter papers post-modified via such a simple way were proved to be of improved binding class selectivity and colorimetric sensitivity, allowing for in-situ colorimetric assay of FCs in an unprecedently wide range of applicable pH (1.0–12.0) with high reliability and fine versatility. Finally, the semiquantitative naked-eye determination of FCs (Allura red, brilliant blue and sunset yellow) in real-world drink samples was experimentally confirmed to be feasible by comparison with the findings of UV–vis absorption spectra, HPLC and mass spectra.

RPA/CRISPR/Cas12a-Based On-Site and Rapid Nucleic Acid Detection of Toxoplasma gondii in the Environment.

Toxoplasma gondii is an opportunistic pathogen widely distributed within the world, poses a huge threat to human health, and causes significant economic losses to the livestock industry. Herein, we developed a portable one-pot detection of T.gondii by combining recombinase polymerase amplification (RPA) and a clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a system. A glass microfiber filter device used for the first step can efficiently extract T.gondii from low-concentration samples. The lyophilized RPA reagents and Cas12a/crRNA reagents are prestored in one Eppendorf tube, and both reactions can be performed on a low-cost thermal controller (∼37 °C), avoiding the drawbacks of the step-by-step addition of components. The developed RPA/CRISPR/Cas12a system exhibits a high selectivity toward the B1 gene amplicon of T.gondii over other parasites with a limit of detection of 3.3 copies/μL. The visual signal readout can be easily realized by a fluorometer or lateral-flow strip. A portable suitcase containing the minimum equipment and lyophilized reagents was adopted for the rapid determination of T.gondii in heavily polluted landfill leachate. This system presents rapidness, robustness and on-site features for the detection of nucleic acids of the parasite, making it a promising tool for field applications in remote areas.

Viscosity Simulation of Glass Microfiber and an Unusual Air Filter with High-Efficiency Antibacterial Functionality Enabled by ZnO/Graphene-Modified Glass Microfiber.

The current global pandemic of new coronary pneumonia clearly reveals the importance of developing highly efficient filtration and fast germicidal performance of multifunctional air filters. In this study, a novel air filter with a controllable morphology based on the rod-like to flower-like zinc oxide/graphene-based photocatalytic composite particles loaded on glass microfiber was prepared by one-step microwave rapid synthesis. The multifunctional air filter shows the following special functions: the 10 mg·L–1 organic pollutant solution RhB was completely degraded within 2 h under a 500 W xenon lamp, and also 99% of Escherichia coli and Staphylococcus aureus were inactivated under a 60 W light-emitting diode lamp. Furthermore, after introducing the controllable morphology zinc oxide/graphene-based photocatalytic composite particles, the filtration efficiency of the multifunctional air filter was also kept at the same level (99.8%) as the one without any addition, indicating no loss of high-efficiency filtration while obtaining the rapid bactericidal function. The rapid antibacterial principle of the multifunctional air filter has also been proposed through the UV–vis spectroscopies, photoluminescence, and electron-spin resonance spectrum. The zinc oxide/graphene-based photocatalytic composite particles tightly coated on the glass microfiber surface could increase the active sites by changing the morphology of zinc oxide and, in the meantime, promote the separation of zinc oxide photo-generated electron–hole pairs to improve the rapid sterilization ability of the multifunctional air filters. In addition, an empirical formula to evaluate the relationship between the composition, viscosity, and viscosity modulus of glass microfiber was proposed by testing the viscosity of glass microfiber composed of 14 different compositions at 1300 and 1400 °C, which can be used as a criterion to evaluate the production technology of glass microfiber filters.

Development of two-dimensional qualitative visualization method for isoflavones secreted from soybean roots using sheets with immobilized bovine serum albumin

A visualization method for the qualitative evaluation of soybean isoflavones secreted from soybean roots by transferring them onto a sheet with immobilized bovine serum albumin (BSA) was developed. BSA was chemically bonded onto a glass microfiber filter. The fluorescence quenching resulting from the interaction of BSA with soybean isoflavones such as daidzein and daidzin was utilized. Fluorescence images before and after soybean roots were placed in contact with the sheets with immobilized BSA were taken with an electron-multiplying charge-coupled device camera. The fluorescence quenching in the images was visualized and analyzed. Soybean isoflavones were extracted from the sheets for quantitative analysis, and the correlation coefficient between the quenched fluorescence intensity per sheet and the total amount of soybean isoflavones was 0.78 (p < 0.01), indicating a high correlation. The quenched fluorescence intensity was lower in pumpkin roots, which do not secrete soybean isoflavone. It was found from analyzed images that soybean isoflavone is secreted in larger amounts from the basal region of the taproot and the tips of the lateral roots of soybean.

A Recommendation for a Pre-Standardized Marine Microalgal Dry Weight Determination Protocol for Laboratory Scale Culture Using Ammonium Formate as a Washing Agent.

Simple SummaryMicroalgae are increasingly recognized as a source of valuable biomass with numerous health benefits. Cleaning of marine microalgal biomass is very crucial for microalgal studies as the salt on the microalgae cells will lead to overestimation of biomass determination. Incomplete washing of salt from microalgae could also interfere with the nutritional analyses. The biomass, especially dry weight, has been utilized for nutritional or compositional evaluation. Although standard methods of marine microalgal dry weight determination are available, these methods did not provide comprehensive details, and the parameters vary among themselves. Without a standard method, a comparison of results among previous studies can be misleading and unreliable. Therefore, the current study aimed to investigate and determine the ideal setting of several parameters in the marine microalgal dry weight determination for laboratory-scale culture. The present findings could assist in developing a standardized protocol to ensure a high quality of biomass for microalgal studies. Microalgal biomass is one of the crucial criteria in microalgal studies. Many reported methods, even the well-established protocol on microalgal dry weight (DW) determination, vary greatly, and reliable comparative assessment amongst published results could be problematic. This study aimed to determine the best condition of critical parameters in marine microalgal DW determination for laboratory-scale culture using four different marine microalgal species. These parameters included the washing process, grades of glass microfiber filter (GMF), GMF pretreatment conditions, washing agent (ammonium formate) concentrations, culture: washing agent ratios (v:v) and washing cycles. GMF grade GF/A with precombustion at 450 °C provided the most satisfactory DW and the highest ash-free dry weight (AFDW)/DW ratio. Furthermore, 0.05 M ammonium formate with 1:2 culture: washing agent ratio and a minimum of two washing cycles appeared to be the best settings of microalgal DW determination. The present treatment increased the AFDW/DW ratio of the four respective microalgae by a minimum of 19%. The findings of this study could serve as a pivotal reference in developing a standardized protocol of marine microalgal DW determination to obtain veracious and reliable marine microalgal DW.

Spinning and Fully Integrated Microdevice for Rapid Screening of Vancomycin-Resistant Enterococcus.

This study introduces a spinning and fully integrated paper-based microdevice that can perform multiple functions, including DNA extraction, amplification, and colorimetric detection, for monitoring two major vancomycin-resistant Enterococci (VREs), which carry the vanA and vanB genes. The spinning microdevice is composed of a stationary part and a spinning part. The square-shaped stationary part has two zones: the lysis and reaction zones. The spinning part, which has a spin wheel-like shape, was inserted perpendicularly into the stationary part so that its two semicircles remained on the upper and lower parts. Sodium hydroxide-treated glass microfiber filter discs, inserted in the upper semicircle, were soaked in the lysis chambers by folding them toward the lysis zone to capture DNA in the lysis chambers. The captured DNA was transferred to the reaction chambers by folding the discs toward the reaction chambers. Water was added to the sodium hydroxide-treated glass microfiber filter discs to elute purified DNA into the reaction chambers. The upper semicircle was then unfolded, and the reaction chambers were sealed for subsequent loop-mediated isothermal amplification (LAMP) for 45 min. After the reaction, the spinning part was spun in the lysis zone direction to bring the lower semicircle, inserted with phenolphthalein-treated glass microfiber filter discs, toward the upper part of the stationary part. By folding it toward the reaction chambers, the lower semicircle came into contact with them and the phenolphthalein-treated glass microfiber filter discs were soaked in the reaction chambers and expressed color after 30 s. Based on the pH change during the LAMP reaction, the phenolphthalein-treated discs remained pink in the absence of target DNA, while those in contact with the positive samples turned colorless. A sensitive detection with a VRE limit of detection of 102 CFU/mL for tap water spiked with VRE carrying the vanA gene was achieved using this microdevice. Both VREs, carrying vanA and vanB genes, were successfully identified from tap water and contaminated equipment surfaces within 75 min. The introduced microdevice demonstrated a rapid, accurate, and sensitive performance for the environmental assessment of VRE contamination in resource-limited regions.

Glass microfiber based method for extraction and detection of BVOCs of Camellia sinensis (L.) O. Kuntze

Under natural and ecological interaction like biotic and abiotic stresses, plants constitutively synthesize secondary metabolites which are extremely necessary for their normal growth and survival. Biogenic volatile organic compounds (BVOCs) are such secondary metabolites from adverse environmental conditions like different biotic/abiotic stresses where herbivory and mechanical wounding, such as leaf cuttings, are easily observed. However, BOVCs released from plucking injury on the young stem of Camellia sinensis (L.) O. Kuntze has very limited understanding which is usually experienced as “pleasing aroma” in the tea plantations. Moreover, “direct volatile injection” is a common method for BOVCs molecular characterization. In this work, a modified method, i.e., vacuum pressure coupled adsorption of BVOCs in glass microfiber filter, was used to firstly explore BOVCs from the stem injured young tea foliages (TV22), followed by molecular detection of its n-hexane fraction by GC-MS analysis. GC-MS chromatogram with stable baseline has shown the presence of a 13 (thirteen) lower MW metabolites (C2-C12) below 3 min of runtime which has signified the successful modification of earlier methods. In terms of power consumption, time, heat sensitive volatiles, and detection of low molecular weight/concentration metabolites, this method has strong advantages over the hydrodistillation method. Coupled with other downstream analyses, this method of extraction and detection of BVOCs of “pleasing aroma” from hand-plucked tea foliages has the potential to be observed for future application in perfume industry as a room, or body freshener.

The Impact of Norepinephrine on Mono-Species and Dual-Species Staphylococcal Biofilms.

The effect of norepinephrine (“NE”) on Gram-negative bacteria is well characterized; however, little is known about the impact of NE on cutaneous Gram-positive skin residents, especially staphylococci. In this study, the impact of NE on monospecies and dual-species biofilms of Staphylococcus epidermidis and S. aureus model strains was investigated for the first time. Biofilms were grown in two different models (on polytetrafluoroethylene (“PTFE”) cubes and glass microfiber filters (“GMFFs”)) and additionally kinetic measurements of bacterial growth was performed. We have shown that NE can affect the biofilm formation of both species with a strong dependence on aerobic or anaerobic culture conditions in different models. It was shown that S. epidermidis suppresses S. aureus growth in dual-species biofilms and that NE can accelerate this process, contributing to the competitive behavior of staphylococci.

Quantitative eDNA estimates show a strong correlation with Northern Pike biomass in a controlled environment

Northern pike, Esox Lucius, is one of the most important species for recreational fisheries in Sweden and as a top-predator; it holds an important role in the food web. Despite its ecological and socioeconomic significance, pike is largely neglected in current monitoring programs because it is seldom caught by conventional monitoring methods. As a result, there is not sufficient data for management authorities to employ biologically justified management strategies. To be able to further understand pike ecology and monitor populations, new monitoring methods are needed. Recent developments in environmental DNA (eDNA) has shown the potential to produce (semi-)quantitative estimates of fish biomass. However, the amount of eDNA in water may vary depending on temperature, fish size, age and density, and it is therefore important to first evaluate the effect of biotic and abiotic factors on eDNA biomass relationships. Here, we evaluated the relationship between eDNA concentration and individual biomass of pike by keeping adult fish of varying size (0.75 – 3.41 kg, n = 11) individually in outdoor mesocosms (~7000 L) filled with water from the adjacent Lake Mälaren. Samples were collected by filtering water through a combination of cellulose nitrate and glass microfiber filter membranes. After a comparison of different extraction methods, the eDNA was extracted using Chelex 100 resin, a low-cost and fast method. Samples were subsequently diluted in 1:8 to alleviate problems from inhibition. A TaqMan assay targeting Cytochrome Oxidase I developed by Olsen et al.(Olsen et al., 2016, 2015) was used to quantify pike eDNA. The results show a strong positive relationship between pike biomass and pike eDNA indicating that the latter represents a promising tool for estimating pike biomass in natural waters.

Preservation of geochemical markers during co-combustion of hard coal and various domestic waste materials

Combustion of domestic waste for heating purposes in non-adapted furnaces is a common environmental problem all over the world since it leads to significant emission of harmful substances to the atmosphere. In this project fly and bottom ash from hard coal and domestic waste co-combustion were investigated on the occurrence and distribution of geochemical markers, polycyclic aromatic hydrocarbons (PAHs), and their alkyl derivatives. Hard coal with a domestic waste admixture (paper, ethylene propylene diene rubber, tire rubber, polyethylene, polyvinyl chloride) was combusted in a certified domestic central heating furnace equipped with a control and measurement system. Fly ash was collected on glass microfiber filters inside the flue gas chimney. Raw fuels, fly and bottom ash extracts were analyzed with gas chromatography–mass spectrometry (GC–MS). Geochemical markers survived the coal/domestic waste combustion and can be identified despite the presence of other organic compounds derived from domestic waste thermal decay. The highest changes in distribution and values of geochemical ratios concern light-weight compounds, i.e. lighter n-alkanes and acyclic isoprenoids (pristane and phytane), with distinct differences between fly and bottom ash. n-Alkanes expulsion significantly decreased values of Pr/n-C17 and Ph/n-C18 ratios. Due to their high molecular weight pentacyclic triterpanes mostly retained their original distributions; however, some shifts in values of their thermal maturity ratios occurred due to artificial maturation of organic matter under the heat of combustion. PAHs diagnostic ratios showed variable utility in the indication of domestic waste admixture to hard coal combusted. The highest sensitivity was found for BaP/BghiP, MPI-1, and MPI-3 whereas Fl/(Fl + Py) rather pointed out at hard coal dominating in the fuel mixture. The addition of EPDM and tires significantly worsened the quality of combustion, which is reflected in high extract yields and the retained hard coal geochemical features such as the Pr/Ph value closest to the raw coal value.

Fabrication of superhydrophobic surface using one-step chemical treatment

The fabrication techniques of hydrophobic and superhydrophobic surfaces have received attention from many researchers. In this study, the change of water contact angle of the glass surface modified with chlorosilane or trichlorosilane compound was investigated. The microscope glass with water contact angle of 88° and 107° were obtained by treating with trimethylchlorosilane (TMCS) and octadecyltrichlorosilane (OTS), respectively. The chemical resistance of hydrophobic layer was evaluated by immersing the treated samples into an acidic or a basic solution. The result showed that OTS bonded to the glass surface more strongly than TMCS. The superhydrophobic state with the highest contact angle of 154° (sliding angle 17°) could be achieved with the glass microfiber filter by using OTS. The similar phenomenon could not be observed with TMCS because the TMCS-treated glass filter remained completely wetted with all investigated concentrations. The hydrophobic layer on the glass slides was strongly affected by abrasive force while the contact angle value of more than 154° was detected in the treated glass filter after 50 cycles of abrasion test on a sandpaper. The scanning electron microscope (SEM) images had revealed the aggregation of the OTS molecules on the glass filter surface. The chemically-treated filter performed both superhydrophobic and superoleophilic properties. The OTS coating showed strong resistance to the organic solvent. Separation of mixture n-hexane and water was successfully demonstrated using the modified filter.

Molecular detection of Acanthamoeba spp. in Seven Crater Lakes of Laguna, Philippines.

Acanthamoeba spp. are ubiquitous free-living amoeba with genotypes that cause severe pathology of the eyes, central nervous systems, and rare reports of cutaneous infections. The Seven Crater Lakes are freshwater water resources in Laguna, Philippines primarily used for aquaculture and tourism. A total of 16 surface water samples were collected from different sampling areas per Crater Lake and placed in sterile plastic containers. Samples were filtered using 1.2 μm pore size, glass microfiber filter. Filtered sediments were placed on non-nutrient agar lawned with Escherichia coli and incubated aerobically at 35 °C for 14 days. Six out of 16 water samples exhibited amoebic growth. Cystic stages revealed circular to stellate morphology under light microscopy which were initially classified as Acanthamoeba spp. DNA from positive isolates were made to react with polymerase chain reaction using Acanthamoeba specific primers JDP1 5′-GGCCCAGATCGTTTACCGTGAA-3′ and JDP2 5′-TCTCACAAGCTGCTAGGGAGTCA-3′confirmed the presence of several Acanthamoeba species. Phylogenetic analysis revealed the presence of seven isolates belonging to Acanthamoeba genotypes T4, T5, and T9. The presence of potentially pathogenic Acanthamoeba genotypes in the Seven Crater Lakes of Laguna signifies risk to human health which necessitates the development of programs, policies, and guidelines on the understanding, prevention, and management of potential human infections.

A simple method to produce Synechocystis PCC6803 biofilm under laboratory conditions for electron microscopic and functional studies.

Cyanobacteria can form biofilms in nature, which have ecological roles and high potential for practical applications. In order to study them we need biofilm models that contain healthy cells and can withstand physical manipulations needed for structural studies. At present, combined studies on the structural and physiological features of axenic cyanobacterial biofilms are limited, mostly due to the shortage of suitable model systems. Here, we present a simple method to establish biofilms using the cyanobacterium Synechocystis PCC6803 under standard laboratory conditions to be directly used for photosynthetic activity measurements and scanning electron microscopy (SEM). We found that glass microfiber filters (GMF) with somewhat coarse surface features provided a suitable skeleton to form Synechocystis PCC6803 biofilms. Being very fragile, untreated GMFs were unable to withstand the processing steps needed for SEM. Therefore, we used polyhydroxybutyrate coating to stabilize the filters. We found that up to five coats resulted in GMF stabilization and made possible to obtain high resolution SEM images of the structure of the surface-attached cells and the extensive exopolysaccharide and pili network, which are essential features of biofilm formation. By using pulse-amplitude modulated variable chlorophyll fluorescence imaging, it was also demonstrated that the biofilms contain photosynthetically active cells. Therefore, the Synechocystis PCC6803 biofilms formed on coated GMFs can be used for both structural and functional investigations. The model presented here is easy to replicate and has a potential for high-throughput studies.

Facile and versatile substrate fabrication for surface enhanced Raman spectroscopy using spark discharge generation of Au/Ag nanoparticles

A simple, one-step gas phase technique for the fabrication of low-cost substrates with tunable plasmonic enhancement is proposed exploiting the unique peculiarities of spark discharge nanoparticle generation in particle mixing and the ease of particle deposition onto glass microfiber filters. The applicability of the spark-based technique to produce substrates for surface enhanced Raman measurements based on Au/Ag binary nanoparticles is discussed. Our results prove that considerable signal enhancement can be achieved over a large surface area, which can be conveniently tuned due to the inherent ability of the spark generator to mix two or more materials. This versatility in particle generation is well complemented by the direct deposition of the nanoparticles onto a filter medium, which makes the proposed method a low-cost and appealingly simple way for fabricating robust substrates for Raman-based applications.

Waste glass microfiber filter-derived fabrication of fibrous yolk-shell structured silicon/carbon composite freestanding electrodes for lithium-ion battery anodes

Si is regarded as the most promising anode material for lithium-ion batteries owing to its high theoretical capacity and low working voltage. Waste glass microfiber filters (GFs) can be an optimal silica resource for nanostructured Si synthesis because they do not require crushing or acid leaching procedures, which are essential for other silica resources. In this study, benefiting from the original filter shape, fibrous yolk-shell structured Si/carbon composite freestanding electrodes are fabricated via magnesiothermic reduction (MgR) and carbon coating processes using GFs not only as the silica precursor for MgR but also as the hard template for carbon coating. The carbon shell acts as a conductive framework for the freestanding electrodes and encapsulates the Si nanoparticles (Si NPs) inside the shell with a void space. The freestanding electrodes exhibit good cycling performance and a high areal capacity of 2.2 mA h cm−2 at the 150th cycle because of the yolk-shell structure, which accommodates the volume expansion of the Si NPs.

A methodology to detect explosive residues using a gelled ionic liquid based field-deployable electrochemical device

A simple and robust, low-cost electrochemical device is proposed for the combined sampling and detection of the trace solid explosive 2,4,6-trinitrotoluene (TNT) from a non-porous surface. Four different substrates were investigated to collect explosive residue – a bare thin-film electrode, glass microfiber filter paper, a gel-polymer electrolyte (GPE), and a GPE-filter paper composite. The GPE contained the hydrophobic room temperature ionic liquid (RTIL) trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([P14,6,6,6][NTf2]) and the polymer poly(methyl methacrylate) (PMMA). A simple “swabbing” technique was used to sample explosive residue on all substrates. Square wave voltammetry was performed to determine the effects of oxygen and moisture on the current response. The most robust method for use in the field – a GPE drop-casted on a TFE – was applied in real environments using a hand-held portable potentiostat. The prototype device was able to detect TNT with a 30 min development time in different ambient environmental conditions. The portability, ease of use and low-cost of the sensor device makes this a viable platform for the rapid onsite detection of explosives.

Alternative use of rice straw ash as natural fertilizer to reduce phosphorus pollution in protected wetland ecosystems

Purpose The uncontrolled discharge of phosphorus into aquatic environment leads to the deterioration of the water bodies. Additionally, the agricultural crops present inside the La Albufera de Valencia Natural Park, rice fields mainly, have a high social and environmental value. However, there is a conflict between private interests (farmers) and public interest in the management of agro-waste produced by them. Nowadays, the option used by the farmers is the uncontrolled burning in the own field. The ashes generated during the combustion process could be used to remove phosphorus loading in water bodies of the Natural Park, contributing to its recovery. Methods Adsorption experiments were carried out in batch mode by using different concentrations (5-100 mgP L-1) of sodium phosphate dibasic (Na2HPO4) placed in 100 mL stoppered conical flask with 50 mL of synthetic wastewater and different amounts of adsorbent, during the selected time (5 days). Adsorption studies were performed with doses varying from 5 to 24 g L-1. After finishing the adsorption experiments, the solution was filtered through glass microfiber filter (1.2 µm). Results The adsorption capacity varies for rice straw ash from 31.91% up to 97.48% and rice straw ash with HCl from 17.49% up to 89.04%. An increase in temperature or dosage had a positive effect in the removal capacity, increasing its adsorption. Removal process of phosphorus was endothermic. Conclusion The use of rice straw ash could be a solution to reduce the phosphate in water bodies, providing an advantage to the proposed alternative of agro-waste management.

Antioxidant/stress response in mouse epidermis following exposure to nitrogen mustard

Nitrogen mustard (NM) is a highly reactive bifunctional alkylating agent that induces inflammation, edema and blistering in skin. An important mechanism mediating the action of NM and related mustards is oxidative stress. In these studies a modified murine patch-test model was used to analyze DNA damage and the antioxidant/stress response following NM exposure in isolated epidermis. NM (20 μmol) was applied to glass microfiber filters affixed to a shaved dorsal region of skin of CD-1 mice. NM caused structural damage to the stratum corneum as reflected by increases in transepidermal water loss and skin hydration. This was coordinate with edema, mast cell degranulation and epidermal hyperplasia. Within 3 h of NM exposure, a 4-fold increase in phosphorylated histone H2AX, a marker of DNA double-stranded breaks, and a 25-fold increase in phosphorylated p53, a DNA damage marker, were observed in the epidermis. This was associated with a 40% increase in 8-oxo-2′-deoxyguanosine modified DNA in the epidermis and a 4-fold increase in 4-hydroxynonenal modified epidermal proteins. At 12 h post NM, there was a 3–75 fold increase in epidermal expression of antioxidant/stress proteins including heme oxygenase-1, thioredoxin reductase, superoxide dismutase, glutathione reductase, heat shock protein 27 and cyclooxygenase 2. These data indicate that NM induces early oxidative epidermal injury in mouse skin leading to an antioxidant/stress response. Agents that enhance this response may be useful in mitigating mustard-induced skin injury.

Superhydrophobic Glass Microfiber Filter as Background-Free Substrate for Quantitative Fluorometric Assays.

We have discovered herein that commonly used laboratory glass microfiber filters can be functionalized as background-free superhydrophobic substrates for quantitative fluorometric assays. In particular, glass microfiber filters (Whatman GF/A) can be treated with low-concentration (20 mM) methyltrichlorosilane/toluene solution to be superhydrophobic (water contact angle >150°) in less than 5 min; the modified glass microfiber filter can be readily patterned with UV/ozone irradiation to create hydrophilic reaction zones on the otherwise superhydrophobic substrate. Compared with traditional cellulose filter paper, the glass microfiber filter has extremely low fluorescence background, which makes it an excellent substrate for preparing quantitative fluorometric assays. In conjunction with smartphone imaging and color analysis, we have showcased a copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC)-based fluorometric assay for copper quantitation on these patterned, superhydrophobic glass microfiber filter substrates. Both the limit of detection and linear response range are comparable with the standard spectrophotometric quantitation in solution and commercial copper detection kits, which augments the application potential of superhydrophobic glass microfiber filters as ideal (e.g., background-free) substrates for the preparation of multiplex microassays and other advanced microanalytical devices based on fluorescence readout.