Search

The adulteration of herbal medicines by dexamethasone or prednisolone is regarded as a serious problem in many communities. Herein, a novel platform for the separation and quantification of both target steroids in herbal medicines based on electrochemical paper-based analytical devices (ePADs) has been created. The ePAD was composed of Whatman SG81 chromatography paper, 3D-printed devices and a commercial screen-printed electrode. Whatman SG81 silica-coated paper was used for the separation of dexamethasone and prednisolone based on the difference in their partition coefficients during the flow of the mobile phase. The optimal mobile phase was composed of 60% ethyl acetate in cyclohexane and required 7 min for separation. The separated steroids on the paper were then quantified by electrochemical detection using differential pulse voltammetry, in which the 3D-printed devices facilitated the measurement. Analytical detection ranges of 10-500 μg mL -1 were obtained for both dexamethasone and prednisolone (r 2  = 0.988 and 0.994, respectively). The limits of detection for dexamethasone and prednisolone were 3.59 and 11.98 μg mL -1 , respectively, whereas the limits of quantification were 6.00 and 20.02 μg mL -1 , respectively. The amounts of both target steroids derived from real herbal medicine samples determined by the proposed method were comparable to those obtained with assays using standard high-performance liquid chromatography. In addition, a simple evaporation step can be used to increase the concentration of the samples before analysis. These ePADs are simple, low-cost, rapid, and very promising for on-site quantitative detection., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this study, we developed a point-of-care assay platform with simultaneous detection and self-calibration capabilities for multiple targets based on a microfluidic paper-based analytical device (μPAD). This system is easily manufactured using a wax printing method on chromatographic paper. The design pattern consists of a zone of detection and a calibrant zone for controlled loading using wax barriers with different thicknesses. We showed the utility and applicability of this approach by a proof-of-concept study for two clinically important markers: glucose and lactate. With the naked eye, the results could be fully distinguished and recorded to evaluate the analytical performance with a flatbed scanner. The detection limits of glucose and lactate were 0.3125 mM and 0.2975 mM, respectively, and simultaneous detection was possible from a small sample (0.4 μL) with high sensitivity. Furthermore, this device has a self-calibration function, which minimizes the influence of environmental conditions (i.e., ambient light intensity, temperature, humidity, and pressure). Therefore, the developed multiplex paper-based device is promising for clinical multianalyte point-of-care testing since it is easy to manufacture, cost-effective, user-friendly, and highly sensitive., (Copyright © 2019 Elsevier B.V. All rights reserved.)

High-performance affinity chromatography is limited by its high cost and high pressure. Paper is made up of porous fiber networks and has the properties of low cost, ease of fabrication, and biodegradable. Due to these advantages, herein, we immobilized beta2-adrenoceptor (β 2 -AR) onto the surface of the polytetrafluoroethylene membrane, a paper-based material, and constructed a G protein-coupled receptor (GPCR)-in-paper chromatographic platform. This platform was characterized by Fourier transform infrared spectroscopy, fluorescence analysis, X-ray photoelectron spectroscopy, and chromatographic studies. These morphological and elemental analysis showed that β 2 -AR was successfully immobilized on the paper surface. The specific drugs have good retentions on the GPCR-in-paper chromatographic platform. The association constants of salbutamol, terbutaline and bambuterol to β 2 -AR were calculated to be 2.02 × 10 4 M -1 , 1.15 × 10 4 M -1 , 1.75 × 10 4 M -1 by adsorption energy distribution, which were in good line with the values from frontal analysis, zonal elution and previous literatures. We demonstrated that the GPCR-in-paper platform was cost-effective, easy to be modified for protein immobilization, and applicable in the receptor-drug interaction analysis. We believe such a platform sheds new light on paper chromatography for receptor-drug interaction analysis and other applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Herein, we report three-dimensional paper chromatography (3D-PC) as a micro-chromatographic platform. The method was based on applying the origami microfluidic device for separation, coupled by colorimetric methods for simultaneous determination. The microfluidic device fabrication was a facile printing approach. Two azo food dyes, Tartrazine (E102) and Indigo carmine (E132), were selected as a model analyte, while carbonate-bicarbonate buffer was used as the mobile phase. Our micro-chromatographic device is associated with two big advantages including needing very small volume of mobile phase ( ~12 µL) and ultrafast separation time (~35 s). Under the optimal conditions, the method provided acceptable linear ranges of 0. 0 g L 1 -18.0 g L 1 (R 2  = 0.997) for E102 and 0.070 g L 1 -10.0 g L 1 for E132 and the limits of detection (3σ/slope) were evaluated as 0.620 and 0.060 g L 1 , respectively. The proposed method was successfully applied in the separation and quantification of these dyes in commercial food products such as jelly, candy, and four kinds of drink samples without any sample preparation prior to analysis. The mean recovery values for the real sample analysis were in the range of 100.14%-102.38% for E132 and E102 respectively. The inter-device relative standard deviations were in the ranges of 1.5%-11.8%. In total, our chromatographic μPAD is small (1.0 cm × 1.0 cm × 0.5 cm), portable, inexpensive, no need of specialized user, requires low volumes of sample (0.5 μL), and can perform separation using 12 μL of aqueous mobile phase in very short time., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Distinguishing a specific biomarker from a biofluid sample containing a large variety of proteins often requires the selective preconcentration of that particular biomarker to a detectable level for analysis. Low-cost, paper-based device is an emerging opportunity in diagnostics. In the present study, we report a novel Zinc oxide nanorods functionalized paper platform for the preconcentration of Myoglobin, a cardiac biomarker. Zinc oxide nanorods were grown on a Whatman filter paper no. 1 via the standard hydrothermal route. The growth of Zinc oxide nanorods on paper was confirmed by a combination of techniques consisting of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS,) scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) analysis. The Zinc oxide nanorods modified Whatman filter paper (ZnO-NRs/WFP) was further tested for use as a protein preconcentrator. Paper-based ELISA was performed for determination of pre-concentration of cardiac marker protein Myoglobin using the new ZnO-NRs/WFP platform. The ZnO-NRs/WFP could efficiently capture the biomarker even from a very dilute solution (Myoglobin < 50 nM). Our ELISA results show a threefold enhancement in protein capture with ZnO-NRs/WFP compared to unmodified Whatman filter paper, allowing accurate protein analysis and showing the diagnostic concept.

Surface-enhanced Raman scattering (SERS) is a powerful analytical tool which enables the detection and identification of analytes adsorbed on nanostructured noble metals. However, SERS analysis of complex mixtures can be challenging due to spectral overlap and interference. In this report, we demonstrate a method to simplify the identification of mixed-analyte samples by coupling SERS detection with chromatographic separation on a nanoplasmonic paper substrate. This "nanopaper" substrate is a silver coated glass microfiber filter paper which possesses large SERS enhancement and can serve as a stationary phase in paper chromatography. Nanopaper is easily synthesized using the silver mirror reaction, making it a highly accessible technology. Nanopaper was successfully used as a combined paper chromatography-SERS (PC-SERS) substrate in the separation and identification of mixed organic dyes. It was further employed to separate and identify lycopene and β-carotene in commercial food products, demonstrating the versatility and utility of nanopaper in the identification of complex mixtures.

Although nucleic acid amplification test (NAT) is widely used for pathogen detection, rapid NAT systems that do not require special and expensive instruments must be developed in order to enable point of care (POC)-NATs, which contribute to early initiation of treatment. As a POC-NAT system, Kaneka DNA chromatography chip (KDCC), developed using DNA tag-bound primer through modified substance, was shown to be suitable for POC testing, due to the rapid detection time, simple procedures, and low manufacturing costs. However, owing to some modifications in primer, the detection performance and amplification speed were shown to be reduced when using KDCC, counteracting the increased speed of detection. To solve these issues and improve the speed of this NAT system, we investigated a better modification substance for KDCC. Here, azobenzene-modified primers were shown to have the highest amplification speed and detection performance in KDCC, of all modifications tested in this study, showing 10-100-fold lower detection limit but maintaining the same reaction time. Additionally, rapid herpes simplex virus detection system with azobenzene modified primers was developed. We believed that this breakthrough will contribute toward enabling greater utilization of POC-NATs for medical care, especially in developing countries and clinics., (Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)

Background: To ensure that PK data generated from DBS samples are of the highest quality, it is important that the paper substrate is uniform and does not unduly contribute to variability. This study investigated any within and between lot variations for four cellulose paper types: Whatman™ FTA(®) DMPK-A, -B and -C, and 903(®) (GE Healthcare, Buckinghamshire, UK). The substrates were tested to demonstrate manufacturing reproducibility (thickness, weight, chemical coating concentration) and its effect on the size of the DBS produced, and the quantitative data derived from the bioanalysis of human DBS samples containing six compounds of varying physicochemical properties., Results & Discussion: Within and between lot variations in paper thickness, mass and chemical coating concentration were within acceptable manufacturing limits. No variation in the spot size or bioanalytical data was observed., Conclusion: Bioanalytical results obtained for DBS samples containing a number of analytes spanning a range of chemical space are not affected by the lot used or by the location within a lot.

The first step in curing a disease is being able to detect the disease effectively. Paper-based microfluidic devices are biodegradable and can make diagnosing diseases cost-effective and easy in almost all environments. We created a three-dimesnional (3D) paper device using wax printing fabrication technique and basic principles of origami. This design allows for a versatile fabrication technique over previously reported patterning of SU-8 photoresist on chromatography paper by employing a readily available wax printer. The design also utilizes multiple colorimetric assays that can accommodate one or more analytes including urine, blood, and saliva. In this case to demonstrate the functionality of the 3D paper-based microfluidic system, a urinalysis of protein and glucose assays is conducted. The amounts of glucose and protein introduced to the device are found to be proportional to the color change of each assay. This color change was quantified by use of Adobe Photoshop. Urine samples from participants with no pre-existing health conditions and one person with diabetes were collected and compared against synthetic urine samples with predetermined glucose and protein levels. Utilizing this method, we were able to confirm that both protein and glucose levels were in fact within healthy ranges for healthy participants. For the participant with diabetes, glucose was found to be above the healthy range while the protein level was in the healthy range.

A detection method of gold nanoparticles in chromatography paper has been developed for a simple, cost-effective and reliable quantitation of immunochromatographic strip test. The time courses of the solution resistance in chromatography paper with the gold nanoparticles solution are electrochemically measured by chrono-impedimetry. The dependence of the solution resistance on the concentration of gold nanoparticles has been successfully observed. The main factor to increase the solution resistance may be obstruction of the ion transport due to the presence of gold nanoparticles. The existence of gold nanoparticles with 1.92 × 10(9) particles/mL in an indistinctly-colored chromatography paper is also identified by a solution resistance measurement. This indicates that the solution resistance assay has the potential to lower the detection limit of the conventional qualitative assay.

This paper presents a simple and low-cost method for patterning poly(dimethylsiloxane) (PDMS) barriers in porous support such as paper for the construction of flexible microfluidic paper-based analytical devices (μPADs). The fabrication method consisted of contact-printing a solution of PDMS and hexane (10:1.5 w/w) onto chromatographic paper using custom-designed rubber stamps containing the patterns of μPADs. After penetrating the paper (∼30 s), the PDMS is cured to form hydrophobic barriers. Under optimized conditions, hydrophobic barriers and hydrophilic channels with dimensions down to 949±88 μm and 771±90 μm (n=5), respectively, were obtained. This resolution is well-suitable for most applications in analytical chemistry. Chemical compatibility studies revealed that the PDMS barriers were able to contain some organic solvents, including acetonitrile and methanol, and aqueous solutions of some surfactants. This find is particularly interesting given that acetonitrile and methanol are the most used solvents in chromatographic separations, non-aqueous capillary electrophoresis and electroanalysis, as well as aqueous solutions of surfactants are suitable mediums for cell lyses assays. The utility of the technique was evaluated in the fabrication of paper-based electrochemical devices (PEDs) with pencil-drawn electrodes for experiments in static cyclic voltammetry and flow injection analysis (FIA) with amperometric detection, in both aqueous and organic mediums., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This article discusses the preparation of novel Paper-PEG interpenetrating polymer network-based membranes as inexpensive alternative to currently available adsorptive membranes. The Paper-PEG membranes were developed for carrying out hydrophobic interaction membrane chromatography (HIMC). PEG is normally very hydrophilic but can undergo phase separation and become hydrophobic in the presence of high antichaotropic salt concentrations. Two variants of the Paper-PEG membranes, Paper-PEG 1 and Paper-PEG 2 were prepared by grafting different amounts of the polymer on filter paper and these were tested for their hydraulic properties and antibody binding capacity. The better of the two membranes (Paper-PEG 1) was then used for purifying the monoclonal antibody hIgG1-CD4 from simulated mammalian cell culture supernatant. The processing conditions required for purification were systematically optimized. The dynamic antibody binding capacity of the Paper-PEG 1 membrane was about 9 mg/mL of bed volume. A single step membrane chromatographic process using Paper-PEG 1 membrane gave high monoclonal antibody purity and recovery. The hydraulic permeability of the paper-based membrane was high and was maintained even after many runs, indicating that membrane fouling was negligible and the membrane was largely incompressible., (Copyright 2007 Wiley Periodicals, Inc.)

Paper spray (PS), as a new ambient ionization method, has been applied for direct qualitative and quantitative analysis. The high sensitivity and minimum internal energy (low spray voltage) with optimized paper spray conditions is a significant request for real application in POCT. In this study, a simple and efficient ambient ionization method is developed by spraying from a mesoporous graphene foams (MGFs)-modified paper surface. The good electrical conductivity of MGFs results in obvious spray voltage decrease. Meanwhile, the MGFs-paper substrate has a well improvement in separation and elution efficiency ascribing to ultrahigh specific surface area and π-π electrostatic stacking property of graphene. In combination a commercial triple quadrupole mass spectrometer, the paper spray is successfully used for analysis of amphetamine in saliva. The linear dynamic ranges expand 10 fold in comparison with unmodified chromatography papers and the low limit of quantitation (LOQ) is as low as 1 pg/mL. A small sample volume (0.5 μL) could be analyzed immediately after spotting, without any pretreatment. The performance of this method was demonstrated for application in fast point-of-care mass spectrometry., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Reports of low-quality pharmaceuticals have been on the rise in the past decade, with the greatest prevalence of substandard medicines in developing countries, where lapses in manufacturing quality control or breaches in the supply chain allow substandard medicines to reach the marketplace. Here, we describe inexpensive test cards for fast field screening of pharmaceutical dosage forms containing beta lactam antibiotics or combinations of the four first-line antituberculosis (TB) drugs. The devices detect the active pharmaceutical ingredients (APIs) ampicillin, amoxicillin, rifampicin, isoniazid, ethambutol, and pyrazinamide and also screen for substitute pharmaceuticals, such as acetaminophen and chloroquine that may be found in counterfeit pharmaceuticals. The tests can detect binders and fillers such as chalk, talc, and starch not revealed by traditional chromatographic methods. These paper devices contain 12 lanes, separated by hydrophobic barriers, with different reagents deposited in the lanes. The user rubs some of the solid pharmaceutical across the lanes and dips the edge of the paper into water. As water climbs up the lanes by capillary action, it triggers a library of different chemical tests and a timer to indicate when the tests are completed. The reactions in each lane generate colors to form a "color bar code" which can be analyzed visually by comparison with standard outcomes. Although quantification of the APIs is poor compared with conventional analytical methods, the sensitivity and selectivity for the analytes is high enough to pick out suspicious formulations containing no API or a substitute API as well as formulations containing APIs that have been "cut" with inactive ingredients.

Background and Objectives: Paper biodiagnostics for blood typing are novel, cheap, fast and easy to use. Agglutinated red blood cells cannot travel through the porous structure of paper, indicating a positive antibody-antigen interaction has occurred. Conversely, non-agglutinated blood can disperse and wick through the paper structure with the ease to indicate a negative result. This principle has been demonstrated to detect blood group phenotypes: ABO and RhD. However, typing for red blood cell antigens such as Rh, Kell, Duffy and Kidd has not yet been explored on paper., Materials and Methods: Two paper testing methods - an elution and a direct flow-through method - were investigated to detect red blood cell antigens excluding the ABO system and RhD. Antigens explored include the following: C, c, E, e, K, k, Fy(a), Fy(b), Jk(a), Jk(b), M, N, S and s, P1, Le(a) and Le(b). The variables tested include the following: reaction time and reagent concentration. The importance of antibody type/structure for successful agglutination on paper was confirmed., Results: Some blood group phenotypes showed less agglutination due to weaker antibody-antigen interactions. Most blood groups with antibodies available as IgM, such as C, c, E, e, K and k, and Jk(a) and Jk(b), and P1, were successful using both methods. However, other blood groups, especially those with antibodies only available as polyclonal antibodies, were unsuccessful and require further scrutiny., Conclusion: Paper can be used as an alternative blood grouping diagnostic tool for selected blood group phenotypes., (© 2014 International Society of Blood Transfusion.)

Background: The enteric subgroup F adenoviruses type 40 (Ad40) and 41 (Ad41) are the second most important cause of acute infantile gastroenteritis after rotaviruses. Repeated community outbreaks have been associated with antigenic changes among the Ad40 and Ad41 strains due to host immune pressure. Therefore large field epidemiological surveys and studies on the genetic variations in different isolates of Ad40 and Ad41 are important for disease control programs, the design of efficient diagnostic kits and vaccines against subgroup F adenoviruses. A novel method using sodium dodecyl sulphate SDS/EDTA-pretreated chromatography paper strips was evaluated for the collection, storage and shipping of Ad40/41 contaminated stool samples., Results: This study shows that adenoviral DNA can be successfully detected in the filter strips by PCR after four months storage at -20 degrees C, 4 degrees C, room temperature (20-25 degrees C) and 37 degrees C. Furthermore no adenoviral infectivity was observed upon contact with the SDS/EDTA-pretreated strips., Conclusions: Collecting, storing and transporting adenovirus type 40 and 41 positive stool samples on SDS/EDTA-pretreated chromatography filter strips is a convenient, biosafe and cost effective method for studying new genome variants and monitoring spread of enteric adenovirus strains during outbreaks.

We developed a novel method that uses sodium dodecyl sulfate-EDTA-treated chromatography paper strips to collect unconcentrated fresh stool samples. After the paper strips were stored for 4 months at room temperature, rotavirus RNA could be successfully amplified by using reverse transcriptase PCR. The use of filter paper strips as a specimen support allows (self-)collection of stool samples by untrained persons. Diarrheal stool samples from remote areas can be stored and transported to a central diagnostic laboratory without the need for freezers or special shipping conditions. This convenient and inexpensive rotavirus sample collection system can be of use in epidemiological surveillance studies and vaccine trials.

One of eight Food Blue No. 1 aluminum lakes (B-1Als) used in the official inspection of coal-tar colors in fiscal year 1999 had a violet sub-spot during paper chromatography and was rejected. To clarify the orgin of the sub-spot, the violet subsidiary color (Sub-V) was isolated from the sample. On the basis of NMR and MS analyses and ion chromatography, the structure of the subsidiary color was elucidated to be 2-[[4-[N-ethyl-N-(3- sulfophenylmethyl)amino]phenyl][4-hydroxyphenyl]methylio]benzenesulfonic acid. The relative content of Sub-V to that of m,m-B-1 in the rejected sample was determined to be 39.5% by HPLC. The relative contents in other submitted samples of B-1Al were in the range of 1.1-3.6%.

A novel washing scheme following antigen-antibody reactions with analyte was used during construction of a fluorescent immunosensor to resolve the background problem in the lateral flow assay with human serum. An immuno-membrane strip was devised to simultaneously measure cardiac troponin I (cTnI), creatinine kinase-MB isoform (CK-MB), and myoglobin to diagnose acute myocardial infarction. This strip was then installed within a cartridge containing a built-in washing solution tank, which was used to supply the solution across the signal generation pad of the strip after the immune reactions. Such cross-flow washing was initiated by onset-signaling from the internal control and began to run automatically upon sample addition. Under optimal conditions, the immunosensor displayed a stably suppressed background baseline, enabling us to attain a low detection limit for cTnI (0.05 ng/mL) as well as favorable reproducibility for repetitive measurements (relative standard deviation <10%). No interference was observed among the different complex formations at the respective analyte sites, and no artifacts were caused by sample matrices. We tested the performance relationship with the Pathfast reference system for positive serum samples (36 for cTnI, 58 for CK-MB, and 17 for myoglobin), and the correlation coefficients were >0.98. This result suggests that the new immunosensor system based on two-dimensional chromatography can be used for clinical testing., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A method is described for Western blotting of peptides as small as 400 daltons (Da). Peptides were separated by tricine-sodium dodecyl sulfate electrophoresis and electroblotted to gelatin-coated PH79 nitrocellulose paper (0.1 micron). The electroblotted peptides were fixed to the nitrocellulose paper for 5-10 min in 4% paraformaldehyde solution. Using anti-rabbit FMRF-amide (Phe-Met-Arg-Phe-NH2) as primary antibody, positive immunoreactivity was detected with an amplified alkaline phosphatase assay which was sensitive to at least 0.5 microgram FMRFamide/lane. When immunoreactivity was determined with 125I-protein A, it was possible to amplify and detect weak signals by increasing the autoradiography time. Therefore, using the 125I-protein A detection method, Western blot analysis of brain extracts from Lymnaea stagnalis (pond snail) and Poecilia reticulata (guppy) indicated the presence of four FMRFamide immunoreactive bands after a 7-day exposure to X-ray film. The most abundant peptide coelectrophoresed with the FMRFamide standard (M(r) 598.8 Da). In addition, this Western blotting procedure also detected APGWamide (Ala-Pro-Gly-Try-NH2; 428.5 Da) and [D-Ala2]-Leu-enkephalinamide (568.7 Da) with their respective specific antibodies.

A paper chromatography assay for adrenocortical steroids, published just as cortisone's therapeutic value in arthritis was announced, had far-reaching consequences. Its use by Upjohn scientists led to the first synthesis of cortisone. Interest in the assay also led the author to an association with Syntex S.A. in Mexico, which he was instrumental in transforming from a small chemical company into the large pharmaceutical firm, Syntex Corporation, having its base of operations in the United States. The major events of this history are described, showing how steroid product development helped establish Syntex and later played a role in the founding of ALZA Corporation.

Unlabelled: The aim of the present work was to validate a paper chromatography system as an alternative way to determine the radiochemical purity of Na(18)F., Methods: The evaluated parameters were specificity, limit of quantification, measurement interval, linearity, precision, accuracy, and robustness., Results: The proposed method proved to be linear (P > 0.05; r(2) = 1.000), precise (relative SD, 8.6%), accurate (mean recovery, 95.9%; relative SD, 1.5%-1.8%), and robust under different conditions since no influence of the operative variables on the chromatographic performance was observed., Conclusion: This system can be used as a reliable alternative method to determine the radiochemical purity of Na(18)F samples that can be easily performed in PET radiopharmacies at low cost.

This paper described a convenient semiquantitative method for colorimetric detection of protein with self-calibration integrated on the test strip. Hydrophilic paper was employed as microfluidic device for running colorimetric assay, tree-shaped design was developed to ensure uniform microfluidic flow for multiple branches. The approach was validated with bovine serum albumin (BSA) colorimetric detection, and colorimetric results observed by naked eyes were consistent with that from apparatus. The device could be coupled with digital transmission of images for remote monitoring system for diagnosis, food control, and environmental analysis., (Copyright 2010 Elsevier B.V. All rights reserved.)

Prototypes of microfluidic paper-based separation devices with amperometric detection were developed and evaluated. Photolithography was used to make a gold electrochemical microcell on polyester and that microcell was coupled to a strip of paper where a chromatographic separation occurs. The device performance was demonstrated with the separation and quantification of uric and ascorbic acid in mixtures. The method provides an analytical alternative for the determination of compounds where low cost and simplicity are essential.

A reagentless bioactive paper-based solid-phase biosensor was developed for detection of acetylcholinesterase (AChE) inhibitors, including organophosphate pesticides. The assay strip is composed of a paper support (1 x 10 cm), onto which AChE and a chromogenic substrate, indophenyl acetate (IPA), were entrapped using biocompatible sol-gel derived silica inks in two different zones (e.g., sensing and substrate zones). The assay protocol involves first introducing the sample to the sensing zone via lateral flow of a pesticide-containing solution. Following an incubation period, the opposite end of the paper support is placed into distilled deionized water (ddH(2)O) to allow lateral flow in the opposite direction to move paper-bound IPA to the sensing area to initiate enzyme catalyzed hydrolysis of the substrate, causing a yellow-to-blue color change. The modified sensor is able to detect pesticides without the use of any external reagents with excellent detection limits (bendiocarb approximately 1 nM; carbaryl approximately 10 nM; paraoxon approximately 1 nM; malathion approximately 10 nM) and rapid response times (approximately 5 min). The sensor strip showed negligible matrix effects in detection of pesticides in spiked milk and apple juice samples. Bioactive paper-based assays on pesticide residues collected from food samples showed good agreement with a conventional mass spectrometric assay method. The bioactive paper assay should, therefore, be suitable for rapid screening of trace levels of organophosphate and carbamate pesticides in environmental and food samples.

The routine method of paper chromatography includes five steps: spotting, separating, drying, spraying/immersing and color development. In this paper, a pre-staining paper chromatography which only consisted of spotting, separating and color development was developed for quantitative analysis of gamma-aminobutyric acid. Compared to the routine paper chromatography, the improved method is clean, rapid, inexpensive and reproducible. The effects of ninhydrin concentration, color temperature, color time and Cu(2+) concentration on the color yield in the ninhydrin reaction were optimized. And then the pre-staining paper chromatography coupled with vis spectrophotometry was applied to gamma-aminobutyric acid quantification. The results indicated that the limit of detection was 0.05 mg mL(-1) and the linear range was from 0.5 to 20.0 mg mL(-1). Furthermore, an excellent correlation coefficient was observed with an R(2)=0.998. The method is accurate (RSD<2.64%), and has good recoveries (102.7-103.9%). The validation of the modified technique was verified by a HPLC method.

Yttrium-90 used for therapy should be of very high radionuclidic (RN) purity (>99.998%) as the most probable contaminant, strontium-90, is a bone seeker with a maximum permissible body burden of 74 kBq (2 microCi) only. None of the current known methods of RN purity estimations is adequate to reliably measure the 90Sr RN impurity at such low levels. Our aim was to develop a reliable technique to accurately determine the amount of 90Sr in 90Y used for therapy. This new technique combines chelate-based extraction with paper chromatography using paper impregnated with 2-ethylhexyl, 2-ethylhexylphosphonic acid (KSM-17), which is a 90Y-specific chelator. A PC strip impregnated with KSM-17 at the point of spotting is used for chromatography. Upon development with normal saline, 90Sr moves to the solvent front leaving 90Y completely chelated and retained at the point of spotting. The activity at the solvent front (90Sr) is quantified by liquid scintillation counting, and the data are compared with the total applied activity to provide the RN purity of the test solution. The method has a sensitivity of > or =74 kBq (2 microCi) of 90Sr per 37 GBq (1 Ci) of 90Y. This novel, innovative, and simple technique offers a reliable solution to the unanswered problem of estimation of 90Sr content in 90Y used for cancer therapy.

Reactions and purifications, including carbon-carbon bond forming reactions, can be carried out on a cellulose support on which the substrates are non-covalently absorbed.

Knowledge of the radiochemical purity of radiopharmaceuticals is mandatory and can be evaluated by several methods and techniques. Planar chromatography is the technique normally employed in nuclear medicine since it is simple, rapid and usually of low cost. There is no standard system for the chromatographic technique, but price, separation efficiency and short time for execution must be considered. We have studied an alternative system using common chromatographic stationary phase and alcohol or alcohol:chloroform mixtures as the mobile phase, using the lipophilic radiopharmaceutical [(99m)Tc(MIBI)₆]⁺ as a model. Whatman 1 modified phase paper and absolute ethanol, Whatman 1 paper and methanol:chloroform (25:75), Whatman 3MM paper and ethanol:chloroform (25:75), and the more expensive ITLC-SG and 1-propanol:chloroform (10:90) were suitable systems for the direct determination of radiochemical purity of [(99m)Tc(MIBI)₆]⁺ since impurities such as (99m)Tc-reduced-hydrolyzed (RH), (99m)TcO(4)(-) and [(99m)Tc(cysteine)₂]⁻ complex were completely separated from the radiopharmaceutical, which moved toward the front of chromatographic systems while impurities were retained at the origin. The time required for analysis was 4 to 15 min, which is appropriate for nuclear medicine routines.

Thevetia peruviana seed carboxyl esterase was employed as a biosensor for the detection of selenium compounds by an enzyme inhibition technique on paper chromatograms. The selenium compounds (sodium selenite and selenium dioxide) appeared as white spots on a magenta background due to the inhibition of Thevetia peruviana seed carboxyl esterase (substrate 1-naphthyl acetate, coupling reagent Fast blue B salt). The minimum detectable amounts were about 5 microg of sodium selenite and 5 microg of selenium dioxide. Many other animal and plant carboxyl esterases gave no inhibition spot under the same conditions. Soil and water samples were fortified with sodium selenite and selenium dioxide. A procedure for preparing test solutions and conditions for paper chromatography was established.

Prior studies have shown that Onchocerca volvulus DNA can be detected in skin snips and in black flies after polymerase chain reaction (PCR) with primers specific for repeated "O-150" DNA sequences. We have adapted a paper chromatography hybridization assay (PCHA) to detect amplified O-150 DNA and compared this method to two established methods, namely agarose gel electrophoresis (AGE) and hybridization enzyme-linked immunosorbent assay (ELISA). The minimum amounts of purified O-150 DNA detected by PCHA, AGE, and ELISA were 5, 10, and 2 ng, respectively. The three methods had similar estimated sensitivities for detecting O. volvulus DNA amplified from skin snips from African subjects with onchocerciasis (88%, 84%, and 91%, respectively). No false positive results were observed with skin snips from uninfected control subjects. The paper chromatography hybridization assay detects PCR products in 30 minutes without electricity or special equipment. This technology brings DNA detection a step closer to widespread use in field settings.

Unlabelled: The purpose of this work was to develop a simple and rapid method to determine the radiochemical purity of 99mTc-bicisate., Methods: A rapid paper chromatographic (PC) method was developed to determine the radiochemical purity of 99mTc-bicisate and compare the results with those of the manufacturer's recommended method. The present PC method included Whatman 3MM paper as the solid phase and ethyl acetate as the solvent., Results: The time for chromatography by this technique was 4-5 min compared to about 23 min by the manufacturer's method. The Rf value of 99mTc-bicisate (Rf = 0.9-1.0) was widely different from those of 99mTcO4- and reduced 99mTc (Rf = 0.0 for both) so the chromatographic strip after development could be readily cut into two segments, in order to determine the labeling yield., Conclusion: No significant difference in labeling yields was found between the present method and the manufacturer's method. The PC method using Whatman 3MM paper and ethyl acetate is a simple and fast technique to determine the radiochemical purity of 99mTc-bicisate and may be substituted for the manufacturer's recommended method to save time.

A miniaturized rapid paper chromatographic technique (MRPC) for quality control of a technetium-99m sestamibi preparation was developed and compared with the manufacturer's and Hung et al. techniques. The MRPC system involves the use of 6.0x0.5cm Whatman 3MM paper strip developed in ethyl acetate. The procedure was completed within 3min while that of the manufacturer and Hung techniques took 30-35 and 4min respectively. The Rf range of 99mTc-sestamibi using MRPC was 0.55-0.75 while that of the other two techniques was 0.9-1.0. The results indicate that MRPC can be used to separate 99mTc-sestamibi from any 99mTc contaminant that migrates with the solvent front. The MRPC is a fast and effective chromatographic technique for routine quality control testing of 99mTc-sestamibi preparation.

A new DNA hybridization technique, based on chromatographic migration of DNA on a nitrocellulose strip passing through an immobilized probe area, is described. The new paper chromatography hybridization assay (PACHA) is faster and simpler to use than the conventional dot hybridization assay. In this assay, an aliquot of biotinylated, PCR-amplified target DNA is applied to one end of a nitrocellulose strip. The DNA migrates to the opposite end of the strip by capillary forces and hybridizes to a specific DNA probe immobilized in a reaction zone (RZ), located in the middle of the strip. Unhybridized DNA migrates away from the RZ. The biotinylated hybrid is visualized by a color reaction employing a streptavidin-alkaline phosphatase (SA-AP) conjugate and a specific chromogenic substrate. The new PACHA technique allows for detection of as little as 1-5 pg of specific human papilloma virus 16 (HPV16) DNA in 25 min of hybridization. In this system, the hybridization efficiency is controlled by the flow velocity of the hybridization solution (HS) and by the volume of the amplified labeled DNA migrating across the immobilized probe. Glycerol (30%) or polyvinyl pyrrolidone (PVP) (1%) reduces the flow rate by a factor of 2.5-3 and increases the sensitivity of the assay by a factor of 5.2 for glycerol and 2.6 for PVP. This novel method ensures efficient hybridization to multiple probes and appears to be superior to currently available solid-phase hybridization techniques.

Ether extraction and paper chromatography were used to separate the main metabolites of vitamin D in plasma [25-(OH), 24,25-(OH)2 and 1,25-(OH)2 vitamin D]prior to radio receptor-assay. The overall procedural loss of the 1,25-(OH)2 vitamin D was 58 +/- 5% (n = 40), corrected for by tracer addition. The sensitivity of the assay was 0.5 fmol/tube, corresponding to 4 pmol/l, and the intra- and inter-assay coefficients of variation were 10.5% and 11.5%, respectively. The range of values measured in healthy controls was 80-200 pmol/l (n = 60), which is in agreement with findings reported in the literature. A comparison of the results of the present procedure with those obtained with a procedure employing C18 purification, disclosed a correlation coefficient of 0.92 (p < or = 0.0001), a slope of 0.89 (p < or = 0.0001) and a small non-significant intercept of 5.0 pmol/l (n = 53).

N-myristoyl-CoA:protein N-myristoyl transferase is the enzyme that catalyzes the covalent transfer of myristic acid to the NH2-terminal glycine residue of a protein, or peptide, substrate. We have established a new, rapid, reliable, and inexpensive myristoyl-CoA:protein N-myristoyl transferase assay. This N-myristoyl transferase assay is based on the binding of the [3H]myristoylated peptide to a P81 phosphocellulose paper matrix and is more convenient for assaying multiple samples than existing procedures. Two peptides, derived from the N-terminal sequences of the type II catalytic subunit of cAMP-dependent protein kinase and pp60src, were used as substrates. A survey of rat and bovine tissue extracts demonstrated that in both cases brain contained the highest NMT activity (i.e., brain greater than spleen greater than heart greater than liver). Under the assay conditions used, the rate of myristoylation was linear for 10 min and with up to 4.0 mg/ml of brain extract.

Introduction: Since Pall-German stopped manufacturing ITLC-SG, it has become necessary to validate alternative stationary phases., Objective: To validate different stationary phases versus ITLC-SG Pall-Gelman in the determination of the radiochemical purity (RCP) of (111)In-pentetreotide ((111)In-Octreoscan) by planar chromatography., Material and Methods: We conducted a case-control study, which included 66 (111)In-pentetreotide preparations. We determined the RCP by planar chromatography, using a freshly prepared solution of 0,1M sodium citrate (pH 5) and the following stationary phases: ITLC-SG (Pall-Gelman) (reference method), iTLC-SG (Varian), HPTLC silica gel 60 (Merck), Whatman 1, Whatman 3MM and Whatman 17. For each of the methods, we calculated: PRQ, relative front values (RF) of the radiopharmaceutical and free (111)In, chromatographic development time, resolution between peaks. We compared the results obtained with the reference method. The statistical analysis was performed using the SPSS program. The p value was calculated for the study of statistical significance., Results: The highest resolution is obtained with HPTLC silica gel 60 (Merck). However, the chromatographic development time is too long (mean=33.62minutes). Greater resolution is obtained with iTLC-SG (Varian) than with the reference method, with lower chromatographic development time (mean=3.61minutes). Very low resolutions are obtained with Whatman paper, essentially with Whatman 1 and 3MM. Therefore, we do not recommend their use., Conclusions: Although iTLC-SG (Varian) and HPTLC silica gel 60 (Merck) are suitable alternatives to ITLC-SG (Pall-Gelman) in determining the RCP of (111)In-pentetreotide, iTLC-SG (Varian) is the method of choice due to its lower chromatographic development time., (Copyright © 2012 Elsevier España, S.L. and SEMNIM. All rights reserved.)

In principle, surface enhanced Raman spectroscopy (SERS) is thought to provide unique identification of a target analyte, even in complex samples or in the presence of multiple analytes. In practice, however, this is not always true for real-world samples due to various forms of interference. In this report, we build upon our previous work on inkjet-printed SERS substrates by using paper and polymer membranes to integrate sample cleanup and analyte separation with SERS detection. Inkjet-printed paper SERS substrates provide a highly sensitive chemical detection platform of unprecedented cost and simplicity. In addition, paper inherently provides unique capabilities, such as capillary-actuated fluid transport and selective molecular retention. Utilizing these properties, we demonstrate two-dimensional chromatographic separation and SERS detection on inkjet-printed paper SERS substrates. Then, we leverage the separation properties of paper and polymer membranes for real applications that feature complex sample matrices, including the detection of down to 5 ppm melamine in infant formula, as well as the quantification of nanograms of heroin in samples contaminated with a highly fluorescent background. The results presented here demonstrate that inkjet-printed paper SERS devices not only provide advantages in terms of sensitivity and cost, but the paper provides inherently integrated sample cleanup capabilities that are not available in traditional SERS substrates and microfluidic SERS devices. These unique capabilities of paper SERS devices enable the identification of targeted analytes even in complex real-world samples.

This paper reports on an inkjet printing method for the fabrication of lateral flow immunochromatographic devices made from a single piece of filter paper by patterning microfluidic channels and dispensing immunosensing inks, requiring only a single printing apparatus. This "paperfluidic" immunosensing device allows for a less time-consuming and more low-cost fabrication compared with the conventional immunochromatographic strips requiring multiple pads, plastic or nylon backing, and a plastic case. A sandwich immunoreaction was performed on the patterned immunosensing paper device, and the sensitivity of the device was optimized with an IgG model analyte. Inkjet-printed antibodies on the test line and the control line were immobilized by physical adsorption, resulting in a very simple fabrication method applicable for pure cellulose surfaces. The color intensity in the test line and the control line was determined both by naked eye and by means of a color scanner in combination with a simple computer program. With the resulting paperfluidic immunosensing device, human IgG concentrations at least down to 10 μg/l could be detected within 20 min. Additionally, in order to demonstrate the feasibility of a total multianalyte sensing system, a combined immuno-chemical sensing device was also fabricated by patterning an additional microfluidic channel for a chemical assay onto the same paper substrate. This low-cost multianalyte paperfluidic sensing device thus demonstrates the feasibility of simple, portable, and disposable tools for pathogen detection in the field of medical, environmental, and food analyses, possibly resulting in useful devices in remote settings and less-industrialized countries.