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OBJECTIVES Current human infant urine collection methods for the field are problematic for the researcher and potentially uncomfortable for the infant. In this study, we compared two minimally invasive methods for collecting infant urine: organic cotton balls and filter paper. MATERIALS AND METHODS We first collected urine from infants using the clean catch method. We then used those samples to compare the performance of filter paper and cotton ball collection protocols. We analyzed the clean catch and cotton samples using commercial estrone-3-glucuronide (E1G) kits and tried two different extraction methods for the filter paper. Using a paired t-test (n = 10), we compared clean catch and cotton samples. We also compared effect sizes within and between methods. RESULTS We were unable to extract enough urine from the filter paper to successfully assay the samples for E1G. The paired t-test revealed a statistically significant difference between the clean catch and cotton methods (t = 2.63, p-value = 0.03). However, the effect size was small (5.91 μg/ml, n = 10, 95% CI = 3.80, 8.02) and similar to or larger than the difference seen between duplicate wells for clean catch and cotton values. DISCUSSION While this study is limited by sample size, our results indicate that filter paper is not a field-friendly method for collecting infant urine. However, we found that organic cotton balls showed similar values to the clean catch method, and we propose this method as an alternative, minimally invasive method for study of E1G in human infant urine.

Researchers are trying to tackle water scarcity in numerous ways. One of those ways is the use of nanotechnology in water processing and purification. The current work involves the fabrication and optimization of activated carbon and graphene-based hybrid water purification system. Five different concentrations of methylene blue and deionized water (DI) dye solutions were used, and they were filtered in three different cycles. For the potential usage on the consumer side, a small-scale, low-cost water filter is developed using activated carbon, commercial filter paper, and graphene nanoplatelets. The filter paper is used to hold mixtures of the activated carbon and graphene nanoplatelets within the water filter. The conductivity, TDS, and pH are measured for the feed water and the processed water using an Oakton EcoTestr and Apera Instruments PH60 Premium Pocket pH meter, respectively. A UV-Vis spectrometer is used to measure the absorption of solutions. The distribution and adsorption of the dye particles were observed by scanning electron microscopy. PRACTITIONER POINTS: These results show the effectiveness of the system in the removal of dye particles above a given particle size. The concentration of the dye solution decreased after every cycle. The GnPs filtration system more effectively dye particles as compared to the filtration system containing only Activated carbon. UV-Vis spectroscopy results showed that the methylene blue dye particles decreased after every cycle. This research can open a broad area of projects toward waste/wastewater practice for particles above a certain particle size.

Nano‐MgO was successfully fabricated by a facile, inexpensive, and environment‐friendly synthetic method using filter paper as a bio‐template. The influence of the concentration of raw material Mg(CH3COO)2·4H2O on the textural properties of nano‐MgO was investigated, and the as‐prepared nano‐MgO was characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X‐ray analysis, thermo gravimetric analysis, Fourier transform infrared spectroscopy. The results of the experiment show the synthetic MgO fibres are composed of 20 nm tiny particles with a surface area of 68.28 m2/g and a pore width of 13 nm. When the concentration of Mg(CH3COO)2·4H2O solution was 0.03 mol/L, the product MgO copied the micro‐morphology of the filter paper. In addition, the photocatalytic activity of the prepared sample was investigated, and the results showed that the nano‐MgO prepared by this method has a higher catalytic activity than that prepared without a template.

Background Olanedine solution is a new antiseptic, and several cases of allergic contact dermatitis caused by the agent were reported in 2018; however, these cases were diagnosed based on positive results in 2-day closed patch testing of Olanedine solution "as is." Objectives To present another case of Olanedine-induced allergic contact dermatitis and to analyze the optimal patch-testing method for this condition. Methods A 34-year-old Japanese female patient and 25 healthy control subjects were patch tested using wet filter paper, which had been treated with 15 μL Olanedine solution, and dried filter paper, which had been treated with 15 μL Olanedine solution and then dried. Results The patient and all of the control subjects exhibited false-positive reactions due to irritation in the 2-day closed patch tests with wet filter paper containing Olanedine solution "as is." The tests with dried filter paper produced a positive reaction on day 7 in the patient, and negative reactions in all control subjects. Conclusions It is preferable to perform 2-day closed patch tests using filter paper with the test solution "as is," which had been dried before application in order to correctly diagnose antiseptic-induced allergic contact dermatitis.

By utilizing the coffee-ring effect and microfluidic paper-based analytical devices (µPADs), this study improved the sensitivity of the determination of norfloxacin in four different food matrices. Micro-PADs in this study were fabricated by designing and embedding wax channels onto cellulose-based filter paper through printing and subjecting the paper to heat to allow the wax to penetrate the paper. Determination of norfloxacin concentration in food samples was achieved by monitoring the colorimetric reaction that occurred between norfloxacin and the added iron (III) nitrate nonahydrate in 5 mM ammonia in each reaction chamber. A transition metal hydroxide was formed through this reaction that resulted in the formation of a solid precipitate to enable the antibiotic to bind to the iron molecule via coordination chemistry. This metal ion-antibiotic complex generated a visible color change. Following the colorimetric reaction, images were taken and subsequently analyzed via ImageJ to determine the relative pixel intensity that was used to infer norfloxacin concentration. The analytical sensitivity of this device was determined to be as low as 50 ppm when analyzing the inner-ring reaction, and as low as 5 ppm when analyzing the outer coffee ring thereby allowing for an alternative cheaper, faster, and more user-friendly method to detect norfloxacin than the conventional methods. PRACTICAL APPLICATION: This novel paper-based microfluidic device can achieve the detection of antibiotic residues in agrifoods in a faster, cheaper, and more user-friendly manner.

BACKGROUND: The inhibitory effect of a moisture‐absorbent sodium polyacrylate (SPA), that is commonly used in disposable diapers, on the bio‐hydrogen (H₂) generation from waste diaper‐like material (WDM) was assessed in dark fermentation studies. Three types of treatments were evaluated in batch bioreactors at 37 °C: mixture of bond paper and filter paper (WDM, no SPA), SPA alone (only SPA or control), and WDM spiked with SPA [paper plus sodium polyacrylate hydrogel (WDM‐SPA)]. The WDM simulated the cellulosic fraction of diaper composition. RESULTS: The units with only SPA did not produce H₂. The WDM‐SPA units exhibited H₂production 25% lower than those of bioreactors loaded with only WDM but no SPA. Cumulative H₂ production was 0.03, 4.22 and 5.50 mmolH₂ gTS–¹ for the SPA, WDM‐SPA and WDM reactors, respectively (0.04, 5.90 and 8.77 mmolH₂ gVS–¹; 0.89, 132.19 and 196.45 NmLH₂ gVS–¹). BioH₂ generation was related to predominance of the fermentation route that produces 1 mol L–¹ of butyric acid (HBu) plus 2 mol L–¹ H₂ in the WDM and WDM‐SPA units, as suggested by the ratio A:B (acetic: butyric acids; A:B

To be effective, steam pretreatment is typically carried out at temperatures/pressures above the glass transition point (Tg) of biomass lignin so that it can partly fluidize and relocate. The relocation of Douglas-fir and corn stover derived lignin was compared with the expectation that, with the corn stover lignin's lower hydrophobicity and molecular weight, it would be more readily fluidized. It was apparent that the Tg of lignin decreased as the moisture increased, with the easier access of steam to the corn stover lignin promoting its plasticization. Although the softwood lignin was more recalcitrant, when it was incorporated onto filter paper, it too could be plasticized, with its relocation enhancing enzymatic hydrolysis. When lignin recondensation was minimized, the increased hydrophobicity suppressed lignin relocation. It was apparent that differences in the accessibility of the lignin present in Douglas-fir and corn stover to steam significantly impacted lignin fluidization, relocation, and subsequent cellulose hydrolysis.

The present study demonstrates the development of a supramolecular porous ensemble consisting of hetero-oligophenylene derivative 6 and Au-Fe3 O4 nanodots. Supramolecular assemblies of AIE-active hetero-oligophenylene derivative 6 served as reactors for the generation of Au-Fe3 O4 nanodots. The as prepared supramolecular ensemble functioned as an efficient recyclable photocatalytic system for C(sp2 )-H bond activation of anilines for the construction of quinoline carboxylates. Interestingly, the "dip catalyst" prepared by depositing PTh-co-PANI-6: Au-Fe3 O4 nanodots on a filter paper served as a recyclable strip (up to 10 cycles) for C-C/C-N bond formation reaction.

Quantitative analysis of amino acids in blood and urine is primarily indicated for the diagnosis of amino acid disorders. The high-performance liquid chromatography (HPLC) technique is frequently used for this detection. The frequency of sample collection on filter paper has been increasing exponentially, and there are many advantages attributed to processing biological samples in this way. The aim of this study was to validate a quantitative analysis of amino acids by HPLC in blood and urine collected on filter paper and to establish reference values in the neonatal period. Dried blood and dried urine samples of respectively 58 and 45 healthy newborns (2-9 days) were collected. Pre-treatment and extraction of samples were done according to the literature. Separation and analysis of amino acids were carried out by HPLC with fluorescence detection. The developed method demonstrated excellent separation, linearity, limits of detection and quantification, repeatability and recovery. The reference values for 17 amino acids were defined in dried blood and urine samples of newborns. This work presents a simple, fast and effective method for the simultaneous analysis of 17 amino acids in blood and urine collected on filter paper in a single run. The reference values were established and validated.

Morphological engineering techniques have recently become popular, since they are used to increase the production of a variety of metabolites and enzymes when fungi are grown in submerged cultures. This study aimed to facilitate cellulase production by adding aluminum oxide to Trichoderma viride My precultures. The results showed that the highest cellulase activity was achieved when aluminum oxide at 10 g/L was used, and the activities of cellulase for filter paper and endoglucanase activity assays increased from 519.11 to 607.35 U/mL by 17.1%, and from 810.08 U/mL to 917.59 U/mL by 13.3%, compared with the control, respectively. Addition of aluminum oxide decreased the size of T. viride My pellets and increased the final pH. The changes in pellet diameter after the addition of different concentrations of aluminum oxide were fitted using a modified exponential decay model, which could precisely predict the pellet size by controlling aluminum oxide concentration. The optimum concentration of microparticles, and therefore pellet size, could significantly improve cellulase production, which is an encouraging step towards commercial cellulase production.

Nutrient, phytochemical, and antinutrient composition of Citrus maxima fruit juice and peel extract were determined. The fruit was procured from a garden in Trans‐Ekulu, Enugu East Local Government Area, Enugu State, Nigeria. Mature undamaged Citrus maxima fruits were thoroughly washed with distilled water to remove contamination, dirt, and air‐dried. The peel was separated from the pulp. The pulp (100 g) was blended and filtered through a muslin cloth to obtain a clear juice. The peel (50 g) was macerated with 200 ml of ethanol for 20 min. The peel extract was filtered through filter paper. The supernatant was concentrated by rotary evaporation. The peel extract was weighed and stored in a plastic container until needed. Proximate, mineral, vitamins, antinutrient, and phytochemical composition of the juice and peel extract were determined using standard procedures. Citrus maxima peel extract contains significantly (p < .05) higher crude fiber (2.58%), fat (9.74%), ash (2.49%), and carbohydrate (71.57%) compared with Citrus maxima juice. Alkaloid, phenolics, and flavonoids were also significantly (p < .05) higher in the peel extract. The mineral composition revealed the order Ca > Na > Ph > Fe > Mg > K in the juice and Ca > Ph > Na > Fe > K > Mg in the peel extract. Vitamin C content of the juice and peel extract were 26.36 mg/100 g and 19.34 mg/100 g, respectively. Citrus maxima peel is highly nutritive and rich in phytochemicals, further research is recommended to investigate its therapeutic effect.

A simple “drop-wipe-test” approach for rapid detection of pesticide residues in fruits was developed based on surface-enhanced Raman spectroscopy (SERS) coupled with wiper-type filter paper substrate. The filter paper was coated with silver nanoparticles (Ag NPs) and used as a flexible and absorbent wiper-type SERS substrate. The first two steps “drop” and “wipe” were combined to simplify the procedures of extraction and sampling of the analyte molecules. “Test” was the last step to obtain the spectral data using a portable Raman spectrometer (Hx-Spec) developed by our laboratory. The entire detection process was completed just in a few minutes. The optimal wipe time of ~15 s was confirmed used to ensure a thorough extraction of analyte molecules. The as-prepared SERS substrate was used for rapid detection of pesticide residue (i.e., thiram) in apple, pear, and grape by “drop-wipe-test” method. Results demonstrate that the concentrations of thiram spiked on the three fruits skin show a linearly relationship with the average intensity (n = 7) of SERS spectra with R-square values of 0.9991, 0.9872, and 0.9841, respectively. The limit of detection of thiram in apple, pear, and grape peel was 4.6261, 5.1799, and 5.7061 ng/cm2, respectively. The detection limits are all below the maximum residue limits for pesticide in food that were set by the National Food Safety Standard of China (GB). The results demonstrate that SERS method coupled with a flexible and absorbent SERS substrate can be used as a practical application for a reliable, rapid, and sensitive detection of pesticide residues.

The domiciliary presence of Triatoma infestans (Klug) (Hemiptera: Reduviidae) after control interventions was reported in recent years. Toxicological studies showed high levels of resistance to pyrethroids suggesting resistance as one of the main causes of deficient control. The aim of the present study was to develop a protocol to test resistance to deltamethrin in T. infestans collected from the field by discriminate concentration. To evaluate field insects, the effect of age (early vs. later) and nutritional state (starved vs. fed) on the deltamethrin susceptibility of each developmental stage was studied. Topical and insecticide impregnated paper bioassays were used. Using the impregnated paper, the susceptibility to deltamethrin was not affected by the age of the stadium and the nutritional states, and varied with the post-exposure time and with the different developmental stages. A discriminant concentration of deltamethrin (0.36% w/v) impregnated in filter paper was established for all developmental stages. Finally, the methodology and the discriminant concentration were evaluated in the laboratory showing high sensitivity in the discrimination of resistance. The present study developed a methodology of exposure to insecticide impregnated papers and proposes a protocol to test T. infestans in field populations with the aim to detect early evolution of resistance to deltamethrin.

There is increasing demand for superhydrophobic materials which could be used for separating oil and water efficiently. In order to avoid secondary pollution, it is desirable to prepare such materials with green technology. Here we present an environment benign method for fabricating superhydrophobic materials by using organic base based solvents in which cellulose can be dissolved and activated. Then dissolved cellulose could be chemical modified with green silanization reagent, and the solvent can be recycled after CO2 is removed. The obtained cellulose nanocoating exhibited excellent hydrophobic effect. Spray it on the filter paper (water contact angle (WCA) is 165°) for oil and water separation, the separation efficiency is more than 95%; spray it on ordinary sponge (WCA is 163°), it can be used as oil absorber. It can also absorb a certain amount of bisphenol A (BPA) (the concentration decreased by 66% from the origin concentration 0.1 mM). Besides the high efficiency for the separation of oil and water, it is resistant to a wide range of pH solutions, which means that it could be used in harsh environments. More importantly, the process is cost-effective, the solvent can be recycled and the whole process is green. Thus the activation method provides a green route for the preparation of other cellulose-based materials.

Two new Naphthalimide based dipodal receptors K1 and K2 has been synthesized and selectively formed upon complexation with cobalt ion. Further, these cobalt complexes (K1.Co2+ and K2.Co2+) were fabricated to nanoaggregate in aqueous medium. The stability of these nanoaggregates was established with DLS, TEM, AFM and emission spectroscopy. The nanoaggregates N1-N2 were utilized to selectively sensing of diethylcyanophosphonate in aqueous medium. The nanoaggregate N1 and N2 exhibit 2 fold enhancement in the emission spectrum in presence of Diethylcyanophosphonate (DECP) which is due to rigidity induced fluorescent enhancement. The detection limit to be achieved for DECP is 21 nM in aqueous medium. Additionally, the solution coated filter paper strip of nanoaggregate N1 can detect DECP, thus providing very simple and low coast sensing kit for DECP.

Specific recognition of ultratrace levels of ions in semi-water using super-quicker methods is still a challenge for environmental monitoring. Herein we report a fluorescent and colormetric sensor (ZH) based on supramolecular self-assembly, whose structure was destroyed by the addition of ultratrace of silver ions. The process promoted either naked eye visible color changes or fluorescence intensity quenched in conjunction with a wide pH range. Systematic studies revealed very high selectivity (0.07 µmol/L) for silver ions, and other common cations, e.g., Hg2+, Cu2+, Cd2+, Pb2+ had nearly no influence on the sensing behavior. This sensor also served as a multiple use of component in sensing materials by addition of I− into the mixture of ZH and Ag+ (about 5 times). What's more, ZH containing filter paper emerged distinct color and fluorescence changes upon exposure to silver (Ag+), which could be used as a portable method to undertake field testing for Ag+.

The knowledge of floral nectar sugar characteristics, such as concentration, ratio and mass, is essential to understand the complex nature of nectar production and pollination systems. Although nectar is commonly stored in ecology, storage reliability and effectiveness have rarely been quantified. Inappropriate nectar storage between sampling and analysis can alter nectar chemistry as a result of enzyme or microbial action. Our review of the literature indicates that measures to preserve nectar sugars before analysis include refrigeration, freezing, the addition of an antimicrobial agent, spotting and drying on filter paper, the addition of a desiccant or a combination of these storage treatments. Nectar stored on filter paper is removed by washing with a solvent before analysis. Elution methods are often complex, not standardised and poorly reported in published work. Existing storage methods have generally been used without an evaluation of their impact on results, but evidence suggests a potentially large impact on result accuracy. Future studies should report storage treatments and elution methods to legitimise comparison among independent studies and provide unbiased evaluation of the results. In view of the wide range of storage methods used and lack of verification of their appropriateness, is imperative that standardised and effective methods be developed to ensure that results are reliable. We recommend the prompt analysis of nectar, detailed description of methods, including size of filter paper and method of elution, and use of sterile techniques. Refereed/Peer-reviewed

Rationale The recent development of isotope ratio infrared spectroscopy (IRIS) was quickly followed by the addition of online extraction and analysis systems, making it faster and easier to measure soil and plant water isotopes. However, memory and sample size effects limit the efficiency and accuracy of these new setups. In response, this study presents a scheme dedicated to estimating and eliminating these two effects. Methods Memory effect was determined by injecting two standard waters alternately. Each standard was injected nine times in a row and analyzed using induction module cavity ring-down spectroscopy (IM-CRDS). Memory coefficients were calculated using a new “multistage jump” algorithm. Sample size effects were evaluated by injecting water volumes ranging from 1 μL to 6 μL. Finally, the influence of cellulose filter paper on the isotopic measurements, the memory, and the sample size effect was evaluated by comparing it with glass filter paper. Results Memory effects were detected for both δ18O and δ2H values, with the latter being stronger. Isotopic differences between replicates of the same plant or soil sample showed a clear decrease after memory correction. A small water volume effect was found only when the injected water volume was larger than 3 μL. However, while the correction method performed well for laboratory-made samples, it did not for field samples, due to the heterogeneity of the isotopic composition of the samples. Stronger memory and water volume effects were found for cellulose filter paper. Conclusions The memory coefficients and the water volume–isotope relationship improved the consistency and accuracy of both laboratory and field data. Our results indicate that cellulose filter paper may not be a suitable medium to measure standard waters and evaluate memory and water volume effects. Finally, a detailed correction and calibration protocol is suggested, along with notes on best practices to obtain good-quality IM-CRDS data. Copyright © 2017 John Wiley & Sons, Ltd.

BACKGROUND Intraoperative diagnosis of central nervous system (CNS) tumors provides critical guidance to surgeons in the determination of surgical resection margins and treatment. The techniques and preparations used for the intraoperative diagnosis of CNS tumors include frozen sectioning and cytologic methods (squash smear and touch imprint). Cytologic specimens, which do not have freezing artifacts, are important as an adjuvant tool to frozen sections. However, if the amount of submitted tissue samples is limited, then it is difficult to prepare both frozen sections and squash smears or touch imprint specimens from a single sample at the same time. Therefore, the objective of this study was to derive cells directly from filter paper on which tumor samples are placed. METHODS The authors established the filter paper-assisted cell transfer (FaCT) smear technique, in which tumor cells are transferred onto a glass slide directly from the filter paper sample spot after the biopsy is removed. RESULTS Cell yields and diagnostic accuracy of the FaCT smears were assessed in 40 CNS tumors. FaCT smears had ample cell numbers and well preserved cell morphology sufficient for cytologic diagnosis, even if the submitted tissues were minimal. The overall diagnostic concordance rates between frozen sections and FaCT smears were 90% and 87.5%, respectively (no significant differences). When combining FaCT smears with frozen sections, the diagnostic concordance rate rose to 92.5%. CONCLUSIONS The current results suggest that the FaCT smear technique is a simple and effective processing method that has significant value for intraoperative diagnosis of CNS tumors. Cancer Cytopathol 2017;125:277–282. © 2016 American Cancer Society.

This paper reports a new way to fast produce surface-enhanced Raman scattering (SERS) substrate within 1 s by in situ photoreduction of AgNO3 and chemical compound containing mercapto group, such as para-aminothiophenol (PATP), dithizone, and 4-mercaptobenzoic acid on filter paper. Ag nanoparticles (Ag-NPs) would form in the area where the laser spot was focused by Raman instrument. In this work, the preparation of Ag-NPs and excitation of SERS signal could be achieved simultaneously within 1 s. However, no SERS signal and Ag-NPs were observed when rhodamine 6G and crystal violet were employed in place of the aforementioned molecules after the same operation. About 0.5 μM PATP, 5 μM dithizone, and 1 μM 4-mercaptobenzoic acid could be fast detected by this method. According to this phenomenon, a fast and sensitive way to detect Hg2+ based on a competitive reaction among PATP, Ag+, and Hg2+ was developed. With the addition of Hg2+, PATP was removed from Ag+ owing to the stronger interaction between –SH and Hg2+. This behavior inhibited the formation of Ag-NPs, leading to a decrease of the intensity of the SERS signal. The decrease of SERS intensity was used to determine the concentration of Hg2+. Under optimal conditions, this method can be utilized to detect Hg2+ at a detectable level of a concentration of 4 nM in aqueous solution. Additionally, the Raman mapping experiment demonstrated good point-to-point repeatability with a relative standard deviation of less than 7%. Therefore, this sensing platform is a promising candidate for fast and real-time mercuric ion detection. Copyright © 2016 John Wiley & Sons, Ltd.

Cellulosic biomass is the most promising feedstock for renewable biofuel production; however, the mechanisms of the heterogeneous cellulose saccharification reaction are still unsolved. As cellulases need to bind isolated molecules of cellulose at the surface of insoluble cellulose fibrils or larger aggregated cellulose structures in order to hydrolyze glycosidic bonds, the "accessibility of cellulose to cellulases" is considered to be a reaction limiting property of cellulose. We have defined the accessibility of cellulose to cellulases as the productive binding capacity of cellulose, that is, the concentration of productive binding sites on cellulose that are accessible for binding and hydrolysis by cellulases. Productive cellulase binding to cellulose results in hydrolysis and can be quantified by measuring hydrolysis rates. In this study, we measured the productive Trichoderma reesei Cel7A (TrCel7A) binding capacity of five cellulosic substrates from different sources and processing histories. Swollen filter paper and bacterial cellulose had higher productive binding capacities of ∼6 µmol/g while filter paper, microcrystalline cellulose, and algal cellulose had lower productive binding capacities of ∼3 µmol/g. Swelling and regenerating filter paper using phosphoric acid increased the initial accessibility of the reducing ends to TrCel7A from 4 to 6 µmol/g. Moreover, this increase in initial productive binding capacity accounted in large part for the difference in the overall digestibility between filter paper and swollen filter paper. We further demonstrated that an understanding of how the productive binding capacity declines over the course of the hydrolysis reaction has the potential to predict overall saccharification time courses. Biotechnol. Bioeng. 2017;114: 533-542. © 2016 Wiley Periodicals, Inc.

Considering the requirements for the commercial production of metal–organic frameworks (MOFs), we investigated the aqueous synthesis of zirconium MOFs. A highly versatile route was identified employing ZrOCl2·8H2O, H2O, acetic acid and the respective linker molecule as starting materials. These synthesis conditions are suitable to obtain zirconium MOFs with different topologies like UiO-66-(OH)2, zirconium fumarate, zirconium mesaconate, DUT-67 or MOF-808 with synthesis times of 1 to 5 h under microwave irradiation. The scalability of the synthesis of zirconium fumarate was demonstrated at multigram scale under reflux conditions using conventional dielectric heating. To ease the recovery of this MOF which bypasses filter paper as a pure product, we identified sodium polyacrylate as a suitable additive to induce aggregation of the particles. Moreover, a custom-made prototype flow reactor was developed which allows for the continuous synthesis of zirconium fumarate and UiO-66-NH2 starting from a slurry of the starting materials. The commonly employed toxic organic solvents needed for activation/purification of the MOFs could be successfully replaced by a basic aqueous solution.

Rationale We describe a novel method for preparing milk samples and profiling their triglyceride (TG) fractions. This method was used to explore how the TG profile of milk modulates as lactation progresses and how the TG profile differs between breasts. Methods Fresh milk was spotted onto Whatman filter paper and air-dried. Liquid Extraction Surface Analysis coupled to Fourier Transform Mass Spectrometry (LESA-MS) was adapted for molecular profiling. Collision-Induced Dissociation (CID) was used to profile fatty acid residues. Results LESA-MS produced the relative abundances of all isobaric TGs described and showed that mammary glands within one individual can produce a different profile of TGs. CID was used to uncover the configuration of isobaric triglycerides, indicating the relative amounts of the fatty acids contributing to that triglyceride's mass. This also indicated the presence of very long chain fatty acids (C26:0 and C26:1) that have not been reported before in human breast milk. Conclusions We conclude that spotting on paper and the use of LESA-MS and CID on milk spots is not only a means for analysing milk in unprecedented detail for this preparation time, but is also amenable to conditions in which collecting and storing fresh milk samples for detailed profiling is prohibitively difficult.

Postharvest herbal product contamination with mycotoxins and mycotoxin-producing fungi represents a potentially carcinogenic hazard. Aspergillus flavus is a major cause of this issue. Available mold detection methods are PCR-based and rely heavily on laboratories; thus, they are unsuitable for on-site monitoring. In this study, a bendable, paper-based lab-on-a-chip platform was developed to rapidly detect toxigenic Aspergillus spp. DNA. The 3.0-4.0 cm(2) chip is fabricated using Whatman™ filter paper, fishing line and a simple plastic lamination process and has nucleic acid amplification and signal detection components. The Aspergillus assay specifically amplifies the aflatoxin biosynthesis gene, aflR, using loop-mediated isothermal amplification (LAMP); hybridization between target DNA and probes on blue silvernanoplates (AgNPls) yields colorimetric results. Positive results are indicated by the detection pad appearing blue due to dispersed blue AgNPls; negative results are indicated by the detection pad appearing colorless or pale yellow due to probe/target DNA hybridization and AgNPls aggregation. Assay completion requires less than 40 min, has a limit of detection (LOD) of 100 aflR copies, and has high specificity (94.47%)and sensitivity (100%). Contamination was identified in 14 of 32 herbal samples tested (43.75%). This work demonstrates the fabrication of a simple, low-cost, paper-based lab-on-a-chip platform suitable for rapid-detection applications.

In this study, a turn-on paper-based optical analytical system with a rapid, sensitive and quantitative response for glucose was developed. The luminescence sensing material, crystalline iridium(III)-Zn(II) coordination polymers, or Ir-Zne, was grown electrochemically on stainless steel mesh and then deposited on filter paper. This sensing substrate was subsequently built up under glucose oxidase encapsulated in hydrogel and then immobilized on egg membrane with the layer-by-layer method. Once the glucose solution was dropped onto the paper, the oxygen content was depleted simultaneously with a concomitant increase in the phosphorescence of Ir-Zne. The detection limit for glucose was 0.05 mM. The linear dynamic range for the determination of glucose was 0.05–8.0 mM with a correlation coefficient (R2) of 0.9956 (y=68.11 [glucose]−14.72). The response time was about 0.12 s, and the sample volume was less than 5 μL. The effects of mesh size, buffer concentration, pH, enzyme concentration, temperature, and interference, and the stability of the biosensor, have also been studied in detail. Finally, the biosensor was successfully applied to the determination of glucose in human serum.

Pyrene-containing water-soluble probes for the fluorescent detection of nitroaromatic compounds (NACs), such as explosive components (2,4-DNT and 2,4,6-TNT) and herbicides (2,4-dinitrocresol, 2,4-DNOC), in aqueous media are reported. In the probes, the introduction of surface-active hydrophilic "heads" at the periphery of lipophilic (i.e., hydrophobic) pyrene "tails" resulted in the formation of highly fluorescent micelle-like aggregates/pre-associates in aqueous solutions at concentrations of ≤10(-5) m. The enhanced fluorescence quenching of the herein reported architectures is achieved in the presence of ultra-trace amounts of TNT or 2,4-DNT with values of Stern-Volmer quenching constant close to 1×10(5) m(-1) and a detection limit as low as 182 ppb. The most hydrophilic probes demonstrated higher response to 2,4-DNT over TNT. Filter paper test strips impregnated with 1×10(-5) m solutions of the probes were able to detect TNT, 2,4-DNT, and other NACs at levels as low as 50 ppb in water.

In this study, we report on the behavioural responses of the Tribolium confusum to 6 blends of cereal volatiles. There were tested four doses (1 ng/min, 10 ng/min, 100 ng/min and 1000 ng/min in 50 μl of hexane applied on filter paper). A Y-tube experiment revealed that T. confusum females and males were attracted to the blend 1, 4 and 5 at the concentrations between 1 and 10 ng/min. Confused T. confusum females and males were not attracted to any concentration of blend 2 and 3. Yet the beetle females and males were repelled by the highest concentrations (1000 ng/min) for all the blends tested and also by the concentration 100 ng/min of all the blends tested, except for blend 1 and 4. Females and males were also repelled by the three blend 6 concentrations tested (10, 100 and 1000 ng/min).

We described a strategy to perform multistep operations on a simple laminated paper-based separation device by using electrokinetic flow to manipulate the fluids. A laminated crossed-channel paper-based separation device was fabricated by cutting a filter paper sheet followed by lamination. Multiple function units including sample loading, sample injection, and electrophoretic separation were integrated on a single paper based analytical device for the first time, by applying potential at different reservoirs for sample, sample waste, buffer, and buffer waste. As a proof-of-concept demonstration, mixed sample solution containing carmine and sunset yellow were loaded in the sampling channel, and then injected into separation channel followed by electrophoretic separation, by adjusting the potentials applied at the four terminals of sampling and separation channel. The effects of buffer pH, buffer concentration, channel width, and separation time on resolution of electrophoretic separation were studied. This strategy may be used to perform multistep operations such as reagent dilution, sample injection, mixing, reaction, and separation on a single microfluidic paper based analytical device, which is very attractive for building micro total analysis systems on microfluidic paper based analytical devices.

Rationale Zero volt paper spray ionization (zvPSI) is a newly developed sample introduction/ionization technique for mass spectrometry (MS), which combines favorable features of paper spray ionization (PSI) and solvent-assisted inlet ionization (SAII). With a simple platform similar to PSI, zvPSI allows direct MS analysis of a broad type of samples (liquid, (semi-)solid, and imprint) without applying voltage. Methods In zvPSI-MS, a rectangular paper slip was used as a sample loader, extraction medium, and droplet emitter to introduce sample extract into the inlet of a mass spectrometer. For (semi-)solid and imprint samples, analyte(s) was directly extracted with solvent and instantaneously introduced into a mass spectrometer by aspiration. Solution samples were analyzed after being dried-up or by dispensing directly onto paper. Ionization was achieved by SAII and ionized molecules were detected by an ion-trap mass spectrometer. Results The developed method allowed direct voltage-free MS analysis of samples on filter paper substrate. Favorable features of PSI and SAII were successfully combined, such as fast data acquisition, flexible sample handlings, and direct extraction capability from solid samples (PSI), with no need for external high-voltage, laser, or nebulizing gas to convert analytes into gas-phase ions (SAII). Comparable to PSI and SAII, a wide variety of compounds such as amino acids, peptides, lipids and synthetic polymers were shown to be analyzed. Conclusions The developed method (zvPSI-MS) expanded the analytical utility of PSI and SAII to voltage-free direct MS analysis of a broad type of samples (liquid, (semi-)solid, and imprint).

Advanced carbon materials are important for the next-generation of energy storage apparatus, such as electrochemical capacitors. Here, the physical and electrochemical properties of carbonised filter paper (FP) were investigated. FP is comprised of pure cellulose and is a standardised material. After carbonisation at temperatures ranging from 600 to 1700 °C, FP was contaminant-free, containing only carbon and some oxygenated species, and its primary fibre structure was retained (diameter ≈20–40 μm). The observed enhancement in conductivity of the carbonised FP was correlated with the carbonisation temperature. Electrochemical capacitance in the range of ≈1.8–117 F g−1 was achieved, with FP carbonised at 1500 °C showing the best performance. This high capacitance was stable with >87 % retained after 3000 charge–discharge cycles. These results show that carbonised FP, without the addition of composite materials, exhibits good supercapacitance performance, which competes well with existing electrodes made of carbon-based materials. Furthermore, given the lower cost and renewable source, cellulose-based materials are the more eco-friendly option for energy storage applications.

The separation of oil-water mixtures in highly acidic, alkaline, and salty environment remains a great challenge. Simple, low-cost, efficient, eco-friendly, and easily scale-up processes for the fabrication of novel materials to effective oil-water separation in highly acidic, alkaline, and salty environment, are urgently desired. Here, a facile approach is reported for the fabrication of stable hydrogel-coated filter paper which not only can separate oil-water mixture in highly acidic, alkaline, and salty environment, but also separate surfactant-stabilized emulsion. The hydrogel-coated filter paper is fabricated by smartly crosslinking filter paper with hydrophilic polyvinyl alcohol through a simple aldol condensation reaction with glutaraldehyde as a crosslinker. The resultant multiple crosslinked networks enable the hydrogel-coated filter paper to tolerate high acid, alkali, and salt up to 8 m H2SO4, 10 m NaOH, and saturated NaCl. It is shown that the hydrogel-coated filter paper can separate oil-water mixtures in highly acidic, alkaline, and salty environment and oil-in-water emulsion environment, with high separation efficiency (>99%).

Engineered nanoparticles (NPs) and natural organic matter (NOM) in the environment may interact with background contaminants such as heavy metals and modify their bioavailability and toxicity. In the present study, the combined influences of 2 common NPs (TiO2 and CeO2 ) and humic acid (HA; as a model NOM) on Cu(II) phytotoxicity to rice were investigated by a 3-d root elongation assay performed on filter paper media. The results showed that the adsorption coefficients of bare TiO2 and CeO2 NPs (100 mg/L) toward Cu(2+) are 2.65 and 4.37, respectively, at an initial concentration of 10 mg/L, suggesting that Cu(II) could be strongly adsorbed by NPs, whereas HA-coated TiO2 and CeO2 NPs further enhanced the adsorption coefficients to 4.37 and 6.85, respectively. In addition, compared with Cu-alone treatment, the addition of bare TiO2 and CeO2 NPs (1000 mg/L) increased the length of rice root by 32.5% and 39.0%, respectively; however, the presence of HA-coated TiO2 and CeO2 NPs increased the root length by 90.2% and 100.1%, respectively, which indicated that the mitigation effect of HA-coated NPs on Cu(II) phytotoxicity was more visible than that of bare NPs. The results demonstrated that coexistence of NPs and HA significantly alleviated Cu(II) phytotoxicity as a result of a decrease in bioavailable soluble Cu(II) concentration, which contributes to an understanding of the potential behavior of NPs in the environment.

This study developed a method on detecting methyl viologen (paraquat) using a CdTe-paper-based visual sensor. The CdTe Qdots were immobilized on the paper using glycerin. The volume percentages of CdTe in glycerin were optimized to be 50%. The sensing principle is that the methyl viologen quenches the fluorescence intensity of CdTe Qdots in a concentration dependent manner. The sensor is linearly response to the logarithm concentration of the methyl viologen in the range from 0.39 µmol/L to 3.89 mmol/L with a detection limit of 0.16 µmol/L and the correlation coefficient R2 of 0.99. Three parallel experiments at the methyl viologen concentration of 38.89 µmol/L give a relative error of 2.45%, which indicates a good reproducibility. The sensor is not disturbed by other pestisides including omethoate, anilofos, machete and glyphosate isopropylamine salt. The advantages of this sensor are disposable, stable, convenient, and easy to operate.

In forensics, bloodstains on dark fabrics might be invisible for the naked eye. Although several visualization, presumptive, and confirmatory blood tests have been developed, all have one or more disadvantages, especially on DNA analysis. We report here the use of a visualization assay that can visually detect blood drops up to 1/20 dilution. In this assay, the fabric is placed between two wet filter papers and covered by glass surfaces on both sides. Pressure is applied on the glass surfaces in which bloodstains transfer onto the filter papers through capillary forces. Detected stains can be tested with other more sensitive presumptive blood tests performed on the filter paper. Even more, DNA analysis can be performed on the transferred bloodstains. The presented visualization assay is easy to perform, extremely cheap, requires little hands on time, and does not affect bloodstain pattern analysis.

The high cost of regular diagnostic kits severely impeded its uses for routine clinical assay and fieldworks. A cost-effective chromatography paper is chemically modified with Ag nanostructures using the simple electroless silver deposition, producing a scalable and disposable substrate for surface-enhanced Raman spectroscopy, as well as a large scale of catalytic active sites over many chemical reactions. Synergetic measurement including surface-enhanced Raman spectroscopy and laser desorption ionization-mass spectrometry is performed on Ag decorated filter paper using a thiol containing compound as indicator, allowing for the acquisition of spatially correlated spectroscopy in the tandem mode. In addition, hydrophilic porous cellulose network that contains a certain amount of liquid naturally served as a chemical reactor for molecular transport and reaction. Positive results from catalytic reaction on metallized paper convincingly demonstrated that total microanalysis system on paper (μ-TASoP), as a compelling alternative would find a wide breadth of applications in developing disposable medical devices and customary laboratory assays. Copyright © 2015 John Wiley & Sons, Ltd.

RATIONALE: Various disease conditions, particularly tumours, can be understood easily by studying changes in the lipid profile of cells. While lipid profiles of tissues have been recorded by desorption electrospray ionization mass spectrometric (DESI-MS) imaging, there is paucity in standardized protocols for sample preparation involving cell cultures to generate reliable results. In this study, we report a method for the direct analysis of lipids from cultured cells by incorporating them onto Whatman 42 filter paper as a substrate for reliable DESI-MS analysis. METHODS: The WERI-RB1 cell line was spotted on commonly used substrates for DESI-MS analysis, such as glass slides, Teflon coated glass slides, thin layer chromatography (TLC) plates, and Whatman 42 filter paper. A comparison of mass spectrometric images with two different lipids was made to understand the behaviour of different surfaces when the same sample was spotted on them. Relative intensities of different lipid peaks in the WERI-RB1 cell line were compared and relative lipid abundances were also compared across two different human retinoblastoma cell lines; WERI-RB1 and Y79. RESULTS: The study demonstrates that good lipid signals can be obtained by DESI-MS when the cells are spotted on Whatman 42 filter paper. Tandem mass spectrometry was performed to identify the lipids as glycerophosphocholines (PC). Better lipid images from assembly of cells were obtained with distinct boundary when they were spotted on Whatman 42 filter paper than other surfaces. CONCLUSIONS: We demonstrate the use of a simple substrate for reliable DESI-MS analysis of cultured cells. This method has the potential to understand various interactions of cells with other external agents. The current method would help in the application of DESI-MS for biology in general and medical sciences in particular. Copyright © 2015 John Wiley & Sons, Ltd.

A freestanding membrane of a 3D network of carbon fibers coated with nitrogen-doped carbon spheres (NC@FCF) was designed through the carbonization of modified filter paper, on the surface of which polydopamine spheres were deposited. It is found that the NC@FCF membrane is composed of interlaced and circuitous carbon fibers, and the carbon spheres are distributed in the interspaces among carbon fibers. After infiltration with sulfur, the S-NC@FCF membrane was directly used as a cathode for Li–S batteries. The freestanding cathode exhibits an excellent rate capability, large charge–discharge capacity, and outstanding cycle performance, exhibiting an initial discharge capacity of 1143.7 mAh g−1 and maintaining 778.2 mAh g−1 after 200 cycles at 0.5 C. The excellent electrochemical performance results from the synergistic effect of the 3D carbon-fiber network, which provides electronic conduction pathways, and the porous structure formed through the accumulation of carbon spheres, which can encapsulate S, absorb polysulfides, and facilitate Li+ transfer.

Microwrinkles were formed by treating poly(dimethylsiloxane) (PDMS) surfaces with a mixture of concentrated sulfuric acid and nitric acid at 80 °C followed by a water rinsing step. The acid treatment oxidized the treated area, which also swelled owing to absorption of water during the rinsing step. This absorption of water induced a compressive stress on the PDMS surface that caused the formation of wrinkles. The appearance of wrinkles was controlled by the time interval between the end of the acid treatment and the beginning of the water rinsing step. Wrinkles were formed when the time interval was shorter than 5 s, as water was absorbed by the hygroscopic acid molecules within the treated surface. For longer time intervals of 300 s, this phenomenon was not observed. Based on these findings, a procedure for forming wrinkles in specific areas was developed by hydrating the chosen areas with wet filter paper cut into specific shapes after the acid treatment. The formation of wrinkles was confined to the area under the piece of paper. The orientation and alignment of the wrinkles at the boundaries were also characterized. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 167–174

In this study, we extend imaging and modeling work that was done in Part I of this report for a pure cellulose substrate (filter paper) to more industrially relevant substrates (untreated and pretreated hardwood and switchgrass). Using confocal fluorescence microscopy, we are able to track both the structure of the biomass particle via its autofluorescence, and bound enzyme from a commercial cellulase cocktail supplemented with a small fraction of fluorescently labeled Trichoderma reseii Cel7A. Imaging was performed throughout hydrolysis at temperatures relevant to industrial processing (50°C). Enzyme bound predominantly to areas with low autofluorescence, where structure loss and lignin removal had occurred during pretreatment; this confirms the importance of these processes for successful hydrolysis. The overall shape of both untreated and pretreated hardwood and switchgrass particles showed little change during enzymatic hydrolysis beyond a drop in autofluorescence intensity. The permanence of shape along with a relatively constant bound enzyme signal throughout hydrolysis was similar to observations previously made for filter paper, and was consistent with a modeling geometry of a hollowing out cylinder with widening pores represented as infinite slits. Modeling estimates of available surface areas for pretreated biomass were consistent with previously reported experimental results. © 2014 Wiley Periodicals, Inc.

A facile photoreduction strategy to attach silver nanoparticles on filter paper (AgNPs@FP) to form surface-enhanced Raman scattering (SERS) substrate array was proposed and examined. As prepared, SERS substrate array was applied to detect low concentration of adenine and other nucleobases in aqueous solutions. In addition, the formed SERS substrate array allows mass analysis of aqueous samples with a requirement of only 10 μL in sample volume. To optimize and understand the parameters in preparations, factors such as the concentrations of citrate and silver nitrate, photoreduction time, and concentration of sodium hydroxide were varied and examined. Para-nitrothiophenol was used as a Raman probe molecule and scanning electron microscope (SEM) images of the substrates were used to explore the influences of experimental factors in the preparation of SERS array. Results indicated that silver ions could be effectively reduced and deposited in/on filter paper with the presence of citrate. The formed AgNPs@FP exhibits a three-dimensional structure as the particles formed on and beneath the surface of the cellulosic fibers could be observed. Deposition of analyte on restricted substrate array rendered reproducible results and the spot-to-spot SERS intensity varied within 8%. At optimal conditions, the substrate enhancement factor approached 107. We demonstrated that the filter paper-based SERS substrates can be used as a suitable tool for biological analysis, and a limit of detection better than 160 nM was obtained in detection of adenine molecules in aqueous solutions with a linear range up to 20 μM. Copyright © 2014 John Wiley & Sons, Ltd.

Palladium nanoparticles dispersed in ammonium salts of hyperbranched polystyrenes are adhesively immobilized on the surface of cotton or filter papers by simply heating with dicarboxylic acids or halide anions. The resulting Pd@cotton and Pd@filter paper behave as reusable catalysts; in particular, Pd@filter paper is useful as catalyst for application to sequential cross-coupling and hydrogenation reactions to produce several different products with just one piece of the paper catalyst.

Twelve solvents were tested for their ability to extract the pigments of Chlorociboria aeruginosa and Scytalidium cuboideum, two fungi used primarily for the spalting of decorative wood. Solvents were assessed on the basis of the saturation of pigment produced, their ability to diffuse through filter paper, and whether they reacted with the extracted pigments. Solvents that performed well in extraction testing were then tested to determine whether they could also dissolve the extracted pigment once dried. Of the solvents tested, only dichloromethane was capable of quick, non-reactive extraction with filter paper diffusion, as well as being able fully to redissolve dried pigment extracted from C. aeruginosa. The results of this study show dichloromethane to be an ideal solvent for extracting and applying fungal pigments that offers new possibilities for spalting in which fungi do not need to be grown directly on a substrate in order to produce pigmented wood.

A smart paper that provided sustained release of benzalkonium chloride (BKC) at a set temperature was prepared. Filter paper impregnated with an oil-in-water emulsion containing BKC, methyl methacrylate monomer, ethylene diamine, and 2,2-azobis(2,4-dimethylvaleronitrile) was immersed in a cyclohexane solution of terephthaloyl chloride. A polyamide film containing the BKC MIP was formed on the paper surface via an interfacial polymerization reaction. Dimethlydistearylammonium bromide (DDB) was then coated over the polyamide film. The interfacial polymerization reaction eliminated the need for preparation of microcapsules of BKC or coating of the paper with a binder, which are methods commonly used for preparation of smart papers. Release of BKC from the paper was studied, and the temperature responses obtained with the DDB coating were evaluated. The smart paper with the BKC MIP and DDB coating showed sustained release of BKC, and this function was obtained in response to a certain temperature. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44530.