Filter Paper Substrate Research Articles

An efficient and easily retrievable dip catalyst based on silver nanoparticles/chitosan-coated cellulose filter paper

Re-use of a catalyst is an important task, which is usually achieved by loading it on easily separable supports such as magnetic substrates. However, we demonstrate here the process of easy and fast catalyst separation from a reaction medium by loading it onto an economically feasible and microscopically high surface substrate of filter paper (FP) made up of cellulose microfibers as catalyst support. To achieve the goal, we coated chitosan (CH) on filter paper (CH-FP) to impart a high affinity of the substrate for metal ion absorption. AgNO3 dissolved in water with a 0.1 M concentration was used as the Ag ion carrier solution, and CH-FP strips with known rectangular dimensions were submerged into it for the metal ion absorption. The metal ion-laden CH-FP strips were dip treated with sodium borohydride (NaBH4) aqueous solution to prepare Ag-nanoparticle loaded CH-FP (Ag/CH-FP). X-ray diffraction and energy dispersive X-ray spectroscopy confirmed the formation of the Ag/CH-FP hybrid. Ag/CH-FP morphology was examined through scanning electron microscopy analysis, which showed the presence of Ag nanoparticles attached to the cellulose microfibers. The prepared Ag/CH-FP was employed as a dip catalyst for the degradation of nitroarene compounds of 2-nitophenol (2-NP) and 4-nitrophenol (4-NP) by NaBH4. Remarkably, the rate constants for 4-NP and 2-NP were 3.9 × 10−3 and 1.7 × 10−3 s−1, respectively. In addition, we discussed the ease of the catalyst retrievability from the reaction mixture and its re-usability.

2,4-D and Glyphosate affect aquatic biofilm accrual, gross primary production, and community respiration

2,4-Dichlorophenoxyacetic acid (2,4-D) and glyphosate are widely used agricultural herbicides commonly found in surface waters near cultivated land. Field experiments were conducted to determine the effects of 2,4-D and glyphosate on biofilms in a pond next to agricultural land in Athabasca, Alberta. Contaminant-exposure substrates (CES) consisted of GF/C glass fiber or a cellulose filter paper substrates placed on specimen jars filled with agar that contained low levels of nitrogen and phosphorus, and different concentrations (15, 9.0, 1.5 mM) of either 2,4-D or glyphosate. Nutrients and herbicide diffused freely through the agar to the substrate surface. CES arrays were deployed 15 cm below the water surface for 22 days, after which biofilms were collected and biomass (chlorophyll a ), autotroph gross primary production (GPP), and heterotroph community respiration (CR) were measured. 2,4-D (15 mM) caused significant decreases in rates of biomass accrual (−22%), GPP (−34%), and CR(−63%). Glyphosate (15 mM) also caused significant decreases in rates of biomass accrual (−50%), GPP (−67%), and CR (−47%). For the contaminant concentrations used, mean flux rates are estimated to be between 50–700 ng cm −2 min −1 .

Zero volt paper spray ionization mass spectrometry for direct analysis of samples on filter paper substrate.

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. 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. 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. 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).

Toxicity of Turmeric Extracts to the Termite Reticulitermes flavipes (Blattodea: Rhinotermitidae).

Turmeric is an important spice crop with documented human health benefits associated with chemicals called curcuminoids. In this study, the termite Reticulitermes flavipes (Kollar) was exposed to different solvent extracts of turmeric to investigate potential termiticidal properties. Treating termites with hexane extracts of purified lab-grade curcuminoids had no effect on termites. However, in continuous exposure assays, the LC(50) for hexane extracts of crude turmeric powder was 9.6 mg, or 1.0 mg starting material per square centimeter of filter paper substrate. These active components were soluble in a range of polar and apolar solvents, but only hexane could selectively fractionate active components away from the inactive curcuminoids. The active constituents of turmeric separated by thin layer chromatography (TLC) fluoresced in short-wave UV light but were not visible in long-wave UV light. By re-extracting TLC-separated bands in hexane and performing bioassays and gas chromatography-mass spectrometry, we demonstrated that termiticidal components of turmeric are extractable as a blend containing mainly ar-turmerone, turmerone, and curlone. This determination is consistent with findings of preceding work by other researchers that investigated insecticidal properties of turmeric in other pest insects.

BIOEFFICACY OF TWO ENTOMOPATHGENIC NEMATODES AGAINST SPODOPTERALITTORALIS BOISDUVAL (LEPIDOPTERA) AND TEMNORHYNCHUS BAAL REICHE(COLEOPTERA) LARVAE

ABSTRACT Efficacy of the two entomopathogenic nematode species, Heterorhabditis bacteriophora Poinar (HP88 strain) and Steirnema glaseri Steiner (NJ strain), was tested on the fifth and third instar larvaeof Spodoptera littoralis (Boisd.) and Temnorhynchus baal (Reiche) under laboratory conditions. Experiments were conducted on filter paper and sandy soil substrates using nematode at 50, 100, 200and 400 infective juveniles/5ml of water. Heterorhabditis bacteriophora was most effective on thefifth instar larvae of S. littoralis whereas S. glaseri was effective against third instar larvae of T. ball third. Insect mortality was high (60-90%) and low (<45%) at higher and lower nematodeconcentrations respectively. Heterorhabditis bacteriophora treated larvae of S. littoralis succumbedto the infection at the higher rates (80-100%) as compared to those treated with S. glaseri. The rate of mortality of S. littoralis was lowest when treated with S. glaseri (2-20%). The differences in the rateof nematode infection and insect mortality under various experimental conditions are attributed tothe difference in the behavior, virulence, rate of penetration and host searching abilities of nematodes and the abilities of insect pest larvae to resist nematode penetration. Present study suggests that entomopathogenic nematodes are important and effective biological control agents of most soil dwelling insect pests.

Photochemical method for decoration of silver nanoparticles on filter paper substrate for SERS application

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.

Laser-Induced Breakdown Spectroscopy (LIBS) Analysis of Calcium Ions Dissolved in Water Using Filter Paper Substrates: An Ideal Internal Standard for Precision Improvement

We report an approach for selecting an internal standard to improve the precision of laser-induced breakdown spectroscopy (LIBS) analysis for determining calcium (Ca) concentration in water. The dissolved Ca(2+) ions were pre-concentrated on filter paper by evaporating water. The filter paper was dried and analyzed using LIBS. By adding strontium chloride to sample solutions and using a Sr II line at 407.771 nm for the intensity normalization of Ca II lines at 393.366 or 396.847 nm, the analysis precision could be significantly improved. The Ca II and Sr II line intensities were mapped across the filter paper, and they showed a strong positive shot-to-shot correlation with the same spatial distribution on the filter paper surface. We applied this analysis approach for the measurement of Ca(2+) in tap, bottled, and ground water samples. The Ca(2+) concentrations determined using LIBS are in good agreement with those obtained from flame atomic absorption spectrometry. Finally, we suggest a homologous relation of the strongest emission lines of period 4 and 5 elements in groups IA and IIA based on their similar electronic structures. Our results indicate that the LIBS can be effectively applied for liquid analysis at the sub-parts per million level with high precision using a simple drying of liquid solutions on filter paper and the use of the correct internal standard elements with the similar valence electronic structure with respect to the analytes of interest.

One-step rapid fabrication of paper-based microfluidic devices using fluorocarbon plasma polymerization

In this work, we demonstrated an all-dry, top-down, and one-step rapid process to fabricate paper-based microfluidic devices using fluorocarbon plasma polymerization. This process is able to create fluorocarbon-coated hydrophobic patterns on filter paper substrates while maintaining the trench and detection regions intact and free of contamination after the fabrication process, as confirmed by attenuated total reflectance–Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. We have shown that the processing time is one critical factor that influences the device performance. For the device fabricated with a sufficiently long processing time (180 s), the sample fluid flow can be well confined in the patterned trenches. By testing the device with an 800 μm channel width, a sample solution amount as small as 4.5 μL is sufficient to perform the test. NO2 − assay is also performed and shows that such a device is capable for biochemical analysis.

Electrospun Cellulose Acetate-Garnet Nanocomposite Magnetic Fibers for Bioseparations

Cellulose acetate fibers with magnetic properties have recently attracted much attention because of their potential novel applications in biomedicine such as for cell and protein separations, magnetic resonance imaging contrast agents, and magnetic filters. In this work, as synthesized yttrium iron garnet and gadolinium substituted yttrium iron garnet nanoparticles have been used to generate magnetic filter paper. Garnet nanoparticles dispersed in cellulose acetate polymer solutions were electrospun as free-standing nonwoven fiber mats as well as on cellulose filter paper substrates resulting in magnetic filter papers. The magnetic fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and superconducting quantum interference device (SQUID) magnetic property measurements. The resulting magnetic polymer nanocomposites can be easily picked up by an external magnet from a liquid medium. Fluorescein isothiocyanate (FITC) labeled bovine serum albumin (BSA) was separated from solution by using the magnetic filter paper.

Ring-Oven Based Preconcentration Technique for Microanalysis: Simultaneous Determination of Na, Fe, and Cu in Fuel Ethanol by Laser Induced Breakdown Spectroscopy

The ring-oven technique, originally applied for classical qualitative analysis in the years 1950s to 1970s, is revisited to be used in a simple though highly efficient and green procedure for analyte preconcentration prior to its determination by the microanalytical techniques presently available. The proposed preconcentration technique is based on the dropwise delivery of a small volume of sample to a filter paper substrate, assisted by a flow-injection-like system. The filter paper is maintained in a small circular heated oven (the ring oven). Drops of the sample solution diffuse by capillarity from the center to a circular area of the paper substrate. After the total sample volume has been delivered, a ring with a sharp (c.a. 350 μm) circular contour, of about 2.0 cm diameter, is formed on the paper to contain most of the analytes originally present in the sample volume. Preconcentration coefficients of the analyte can reach 250-fold (on a m/m basis) for a sample volume as small as 600 μL. The proposed system and procedure have been evaluated to concentrate Na, Fe, and Cu in fuel ethanol, followed by simultaneous direct determination of these species in the ring contour, employing the microanalytical technique of laser induced breakdown spectroscopy (LIBS). Detection limits of 0.7, 0.4, and 0.3 μg mL(-1) and mean recoveries of (109 ± 13)%, (92 ± 18)%, and (98 ± 12)%, for Na, Fe, and Cu, respectively, were obtained in fuel ethanol. It is possible to anticipate the application of the technique, coupled to modern microanalytical and multianalyte techniques, to several analytical problems requiring analyte preconcentration and/or sample stabilization.

Near-infrared diffuse reflectance spectroscopy with sample spots and chemometrics for fast determination of bovine serum albumin in micro-volume samples

Abstract Near-infrared diffuse reflectance spectroscopy (NIRDRS) has attracted more and more attention in analyzing the components in samples with complex matrices. However, to apply this technique to micro-analysis, there are still some obstacles to overcome such as the low sensitivity and spectral overlapping associated with this approach. A method for fast determination of bovine serum albumin (BSA) in micro-volume samples was studied using NIRDRS with sample spots and chemometric techniques. 10 μL of sample spotted on a filter paper substrate was used for the spectral measurements. Quantitative analysis was obtained by partial least squares (PLS) regression with signal processing and variable selection. The results show that the correlation coefficient ( R ) between the predicted and the reference concentration is 0.9897 and the recoveries are in the range of 87.4%–114.4% for the validation samples in the concentration range of 0.61–8.10 mg/mL. These results suggest that the method has the potential to quickly measure proteins in micro-volume solutions.

Evaluation of cellulolytic activity in insect digestive fluids

Efficient and low-cost cellulolytic enzymes are urgently needed to degrade recalcitrant plant biomass during the industrial production of lignocellulosic biofuels. Here, the cellulolytic activities in the gut fluids of 54 insect species that belong to 7 different taxonomic orders were determined using 2 different substrates, carboxymethyl cellulose (CMC) (approximating endo-β-1,4-glucanase) and filter paper (FP) (total cellulolytic activities). The use of CMC as the substrate in the zymogram analysis resulted in the detection of distinct cellulolytic protein bands. The cellulolytic activities in the digestive system of all the collected samples were detected using cellulolytic activity analysis. The highest CMC gut fluid activities were found in Coleoptera and Orthoptera, while FP analysis indicated that higher gut fluid activities were found in several species of Coleoptera and Lepidoptera. In most cases, gut fluid activities were higher with CMC than with FP substrate, except for individual Lepidoptera species. Our data indicate that the origin of cellulolytic enzymes probably reflects the phylogenetic relationship and feeding strategies of different insects.

Using ion-selective electrodes to study the drug release from porous cellulose matrices.

Polyvinyl chloride (PVC)-based solid-contact ion-selective electrodes (SC-ISEs), responding to propranolol hydrochloride (Pr+) and lidocaine hydrochloride (Ld+) cations as the model drugs with potassium tetrakis(4-chlorophenyl) borate (KTpClPB) as the ion exchanger, were studied. Different drug-polymer solutions were prepared with the model drugs, using different blend ratios of ethylcellulose (EC) and hydroxypropyl cellulose (HPC). Two different solid dosage forms were used. Polymer films were produced by solvent casting method and drug containing porous cellulose samples were prepared by depositing the drug-polymer solutions onto filter paper substrates. The quality of the electrodes and the release profile of Pr+ and Ld+ were investigated with the potentiometric method. The results were compared to UV spectrophotometry. The electrodes were found to be sensitive, precise and functional with a Nernstian behavior over the range of 1.0 × 10−3–3.1 × 10−6 M (9.2 × 10−4–3.0 × 10−1 mg/mL) and 1 × 10−3–2 × 10−6 M (5.4 × 10−4–2.7 × 10−1 mg/mL) at 25 °C for Pr+ and Ld+ sensitive electrodes, respectively. The dynamic response time for the electrodes was less than 10 s. The Pr+ release from porous filter paper was always higher than its equivalent film formulation. Also, lidocaine had higher and faster release from the samples with higher drug concentration. The comparison of the two analytical methods showed near identical results. The ISEs provided a powerful and flexible alternative to UV method in determination of drug release from porous cellulose substrates in a small scale dissolution testing.

Characterization of a commercial cellulase for hydrolysis of agroindustrial substrates

This work is focused on the characterization of a commercial cellulase in terms of optimum pH and temperature, stability to pH and temperature and affinity of this enzyme to several substrates, determining the Michaelis-Menten parameters. Maximum activity of cellulase was obtained for the temperature range from 40 to 50 °C and pH from 5.2 to 5.5. Enzyme activity decreased only 15% after 150 h of reaction at temperatures between 30 and 50 °C. No loss of activity was observed at pH 5.0 and 5.5. The cellulase showed satisfactory results in the hydrolysis of agroindustrial substrates, since similar activity was verified on filter paper and other agroindustrial substrates.

LarvalBradysia impatiens(Diptera: Sciaridae) Potential for Vectoring Pythium Root Rot Pathogens

A series of laboratory experiments were conducted to investigate the capacity of Bradysia impatiens (Johannsen) larvae to ingest propagules from two strains each of Pythium aphanidermatum (Edson) Fitzp. and P. ultimum Trow and transmit the pathogens to healthy geranium seedlings on a filter-paper substrate in petri dishes. The capacity of fungus gnat larvae to transmit P. aphanidermatum to seedlings rooted in a commercial peat-based potting mix and germination of Pythium oospores and hyphal swellings before and after passage through the guts of larval fungus gnats were also examined. Assays revealed that Pythium spp. transmission by larval fungus gnats varied greatly with the assay substrate and also with the number and nature of ingested propagules. Transmission was highest (65%) in the petri dish assays testing larvae fed P. aphanidermatum K-13, a strain that produced abundant oospores. Transmission of strain K-13 was much lower (<6%) in plug cells with potting mix. Larvae were less efficient at vectoring P. ultimum strain PSN-1, which produced few oospores, and no transmission was observed with two non-oospore-producing strains: P. aphanidermatum Pa58 and P. ultimum P4. Passage of P. aphanidermatum K-13 through larval guts significantly increased oospore germination. However, decreased germination of hyphal swellings was observed following larval gut passage for strains of P. ultimum. These results expand previous studies suggesting that larval fungus gnats may vector Pythium spp.

Rapid analysis of whole blood by paper spray mass spectrometry for point-of-care therapeutic drug monitoring

Paper spray mass spectrometry is applied to oncology drugs in fresh whole blood samples supported on filter paper substrates instead of dry blood as done previously. Addition of the coagulant alum clotted the blood and allowed for immediate sample analysis. The coagulant did not interfere with the function of the paper spray nor did it add features to the mass spectra. Quantitative analysis of therapeutic drugs in the blood was achieved utilizing internal standards which were pre-spotted onto the filter paper. Eight oncology drugs were examined, with lower limits of detection ranging between 0.5 and 17 ng mL(-1) and linear dynamic ranges greater than two orders of magnitude. Inter-day accuracies of quality controls for pazopanib ranged from 102 to 118%, with imprecisions of 9 to 13%. This one-step method requires 10 μL of blood, a drop of solvent, and takes 45 seconds per trial. These results indicate applicability to point-of-care therapeutic drug monitoring in a clinical setting.

Determination of Lysine by Ag@SiO 2 Nanoparticles Enhanced Room Temperature Phosphorescence of Fluorescein Isothiocyanate on Filter Paper Substrate

Determination of Lysine by Ag@SiO ₂ Nanoparticles Enhanced Room Temperature Phosphorescence of Fluorescein Isothiocyanate on Filter Paper Substrate

Silver nanoparticle-treated filter paper as a highly sensitive surface-enhanced Raman scattering (SERS) substrate for detection of tyrosine in aqueous solution

Highly sensitive SERS substrates based on deposition of silver nanoparticles on commercially available filter paper were prepared in this work, and used to overcome problems found in analyses of aqueous samples. To prepare silver nanoparticle- (AgNP) doped filter substrates, a silver mirror reaction was used. The procedures for substrate preparation were systematically optimized. Pretreatment of filter paper, reaction time, temperature, and concentration of reagents for silver mirror reactions were studied. The morphologies of the resulting substrates were characterized by field-emission scanning electron microscopy (FE-SEM) and correlated with the SERS signals by probing with p-nitrothiophenol (pNTP). Filter papers with different pretreatments were found to have different sizes and distributions of AgNPs. The best performance was found when filter paper was pre-treated with ammonia solution before growth of AgNPs. Based on the SEM images, the resulting AgNPs had roughly spherical shape with a high degree of uniformity. The silver-coated filter paper substrates provide much higher SERS signals compared to glass substrates and the reproducibility was improved significantly. Based on statistical analyses, the relative standard deviations for substrate-to-substrate and spot-to-spot were both were less than 8% and the enhancement factors for the substrates were, in general, higher than 107. The SERS substrates were used to selectively detect tyrosine in aqueous solution. Results indicate that filter-based SERS substrates are highly suited to detection of tyrosine. Compared to glass-based SERS substrates, 50 times more SERS signal was observed in detection of tyrosine. The linear range can be up to 100 μM with a detection limit of 625 nM (S N −1 = 3).

An assessment of the effectiveness of 5-methylthioninhydrin within dual action reagents for latent fingerprint development on paper substrates

A critical investigation of 5-methylthioninhydrin (5MTN) is presented as a 'dual action' formulation component for the development of latent finger marks on paper substrates. Preparation of a dual action reagent was performed by combining proportions of 5MTN and zinc chloride (ZnCl(2)) in a pre-mixed solution. Developed prints (deposited on filter paper substrates) could be subsequently visualised in both colour and fluorescence modes. Finger mark quality was graded using a quartered print approach for a number of reagent compositions to deliver an optimised formulation recipe. To fully appraise 5MTN in comparison to currently employed chemistries, this reagent was evaluated against three alternative amino acid selective reagents, ninhydrin, 1,8-diazafluorenone (DFO) and 1,2-indandione/ZnCl(2). Six common paper types were used for this purpose and split depletion finger marks from six donors were collected. Finger mark sets were also left for two days or two weeks to show the effect of ageing on development quality. For the first time, it was shown that 5MTN/ZnCl(2) is effective as a 'dual action' reagent under the United Kingdom climate conditions. However, results presented herein show that the existing recommended chemistries and the 1,2 indandione/ZnCl(2) process are all more effective than this new latent finger mark enhancement reagent. In a preliminary sequencing study, we show the effectiveness of the existing DFO-ninhydrin sequence over dual action reagents.

Preparation of super-hydropbobic titanium oxide film by sol–gel on substrate of common filter paper

A rough TiO2 film was fabricated by sol–gel technique, the film exhibits perfect super-hydrophobicity with a contact angle of 150° and glide angle of about 5° after being modified with octyltrimethoxysilane. The super-hydrophobicity was converted to super-hydrophilicity by the irradiation of ultraviolet light for 20 h, the irradiated super-hydrophilic film evolves to be hydrophobic with a contact angle of about 120° on the condition of being placed in dark for 2 weeks. Finally the property of super-hydrophobicity of TiO2 film modified with octyltrimethoxysilane was discussed on the basis of Cassie’s theory.