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The rapid spread of SARS-CoV-2 caused the COVID-19 pandemic and accelerated vaccine development to prevent the spread of the virus and control the disease. Given the sustained high infectivity and evolution of SARS-CoV-2, there is an ongoing interest in developing COVID-19 serology tests to monitor population-level immunity. To address this critical need, we designed a paper-based multiplexed vertical flow assay (xVFA) using five structural proteins of SARS-CoV-2, detecting IgG and IgM antibodies to monitor changes in COVID-19 immunity levels. Our platform not only tracked longitudinal immunity levels but also categorized COVID-19 immunity into three groups: protected, unprotected, and infected, based on the levels of IgG and IgM antibodies. We operated two xVFAs in parallel to detect IgG and IgM antibodies using a total of 40 μL of human serum sample in

The highly contagious nature and 100% fatality rate contribute to the ongoing and expanding impact of the African swine fever virus (ASFV), causing significant economic losses worldwide. Herein, we developed a cascaded colorimetric detection using the combination of a CRISPR/Cas14a system, G-quadruplex DNAzyme, and microfluidic paper-based analytical device. This CRISPR/Cas14a-G4 biosensor could detect ASFV as low as 5 copies/μL and differentiate the wild-type and mutated ASFV DNA with 2-nt difference. Moreover, this approach was employed to detect ASFV in porcine plasma. A broad linear detection range was observed, and the limit of detection in spiked porcine plasma was calculated to be as low as 42-85 copies/μL. Our results indicate that the developed paper platform exhibits the advantages of high sensitivity, excellent specificity, and low cost, making it promising for clinical applications in the field of DNA disease detection and suitable for popularization in low-resourced areas.

Environmental toxic pollutants and pathogens that enter the ecosystem are major global issues. Detection of these toxic chemicals/pollutants and the diagnosis of a disease is a first step in efficiently controlling their contamination and spread, respectively. Various analytical techniques are available to detect and determine toxic chemicals/pathogens, including liquid chromatography, HPLC, mass spectroscopy, and enzyme-linked immunosorbent assays. However, these sensing strategies have some drawbacks such as tedious sample pretreatment and preparation, the requirement for skilled technicians, and dependence on large laboratory-based instruments. Alternatively, biosensors, especially paper-based sensors, could be used extensively and are a cost-effective alternative to conventional laboratory testing. They can improve accessibility to testing to identify chemicals and pollutants, especially in developing countries. Due to its low cost, abundance, easy disposal (by incineration, for example) and biocompatible nature, paper is considered a versatile material for the development of environmentally friendly electrochemical/optical (bio) sensor devices. This review presents an overview of sensing platforms constructed from paper, pointing out the main merits and demerits of paper-based sensing systems, their fabrication techniques, and the different optical/electrochemical detection techniques that they exploit.

In the present article we report a new hybrid microfluidic device (hyFlow) comprising a disposable paper electrode and a three-dimensional (3D) printed plastic chip for the electrochemical detection of a magnetic bead-silver nanoparticle (MB-AgNP) bioconjugate. This hybrid device evolved due to the difficulty of incorporating micron-scale MBs into paper-only fluidic devices. Specifically, paper fluidic devices can entrap MB-containing conjugates within their cellulose or nitrocellulose fiber matrix. The hyFlow system was designed to minimize such issues and transport MB conjugates more efficiently to the electrochemical detection zone of the device. The hyFlow system retains the benefit of fluid transport by pressure-driven flow, however, no pump is required for its operation. The hyFlow device is capable of detecting either pre-formed MB-AgNP conjugates or conjugates formed in situ. The detection limit of AgNPs using this device is 12 pM, which represents just 22 AgNPs per MB.

In paper-based microfluidics, the simplest devices are colorimetric, giving qualitative results. However, getting quantitative data can be quite a bit more difficult. Distance-based devices provide a user-friendly means of obtaining quantitative data without the need for any additional equipment, simply by using an included ruler or calibrated markings. This article details the development of a quantitative DNA detection device that utilizes the aggregation of polystyrene microspheres to affect the distance that microspheres wick through filter paper. The microspheres are conjugated to single-stranded DNA (ssDNA) oligomers that are partially complementary to a target strand and, in the presence of the target strand, form a three-strand complex, resulting in the formation of aggregates. The higher the concentration of the target strand, the larger the aggregate, and the shorter the distance wicked by the microspheres. This behavior was investigated across a wide range of target concentrations and under different incubation times to understand aggregate formation. The device was then used to successfully detect a target strand spiked in extracted plant DNA.

Pathogenic bacteria pose a serious threat to public health, and the rapid and cost-effective detection of such bacteria remains a major challenge. Herein, we present a DNAzyme-based fluorescent paper sensor for Klebsiella pneumoniae. The DNAzyme was generated by an in vitro selection technique to cleave a fluorogenic DNA-RNA chimeric substrate in the presence of K. pneumoniae. The DNAzyme was printed on a paper substrate in a 96-well format to serve as mix-and-read fluorescent assay that exhibits a limit of detection (LOD) 105  CFUs mL-1 . Evaluated with 20 strains of clinical bacterial isolates, the DNAzyme produced the desired fluorescence signal with the samples of K. pneumoniae, regardless of their source or drug resistance. The assay is simple to use, rapid, inexpensive, and avoids the complex procedures of sample preparation and equipment. We believe that this DNAzyme-based fluorescent assay has potential for practical applications to identify K. pneumoniae.

Several studies have reported on wide-spread contamination of U.S. paper currency with cocaine and to a lesser extent other illicit drugs. Canines are trained and employed to search for and alert to drugs. Canine alert to currency has been used as evidence that currency has been directly involved in illicit drug trafficking to justify currency seizure and forfeiture. This assertion, particularly when the only evidence is based upon canine alert, has been challenged in the courts considering that most currency in circulation is contaminated with cocaine. Comprehensive review of the scientific literature establishes that (i) 67-100% of circulated U.S. currency is contaminated with cocaine ranging from a few nanograms to over one milligram/bill (ii) various biological and environmental parameters impact canine alert to drugs. It is concluded that canine alert to U.S. currency is not sufficiently reliable to determine that currency was directly used in an illicit drug transaction.

Several studies have reported on wide-spread contamination of U.S. paper currency with cocaine and to a lesser extent other illicit drugs. Canines are trained and employed to search for and alert to drugs. Canine alert to currency has been used as evidence that currency has been directly involved in illicit drug trafficking to justify currency seizure and forfeiture. This assertion, particularly when the only evidence is based upon canine alert, has been challenged in the courts considering that most currency in circulation is contaminated with cocaine. Comprehensive review of the scientific literature establishes that (i) 67-100% of circulated U.S. currency is contaminated with cocaine ranging from a few nanograms to over one milligram/bill (ii) various biological and environmental parameters impact canine alert to drugs. It is concluded that canine alert to U.S. currency is not sufficiently reliable to determine that currency was directly used in an illicit drug transaction.

PurposeOveractive bladder syndrome is defined as urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence in the absence of urinary tract infection or another obvious pathological condition. Electronic questionnaires have been used in a few specialties with the hope of improving treatment outcomes and patient satisfaction. However, they have not been widely used in the urological field. When treating overactive bladder, the main outcome is to improve patient quality of life. The primary objective of this study was to evaluate whether electronic questionnaires would be equally accepted as or preferred to paper questionnaires. The secondary objective was to look at the preference in relation to patient age, education and iPad® tablet familiarity.Materials and methodsWe prospectively evaluated the iList® electronic questionnaire application using a friendly iPad tablet in patients with overactive bladder who presented to the urology clinic at our institution. Each of the 80 patients who were recruited randomly completed the validated OABSS (Overactive Bladder Symptom Score) and the PPBC (Patient Perception of Bladder Condition) questionnaires in paper and electronic format on the tablet. Variables potentially associated with the outcomes of interest included demographic data, questionnaire method preference, patient response rate and iPad familiarity. We used the 2-sided Z-test to determine whether the proportion of patients who considered the tablet to be the same, better or much better than paper was significantly greater than 50%. The 2-sided chi-square test was applied to assess whether the intervention effect significantly differed among the demographic subgroups.ResultsA total of 80 patients 21 to 87 years old were enrolled in the study from November 2015 to August 2016. Of the patients 53% were female and 49% were 65 years or younger. The incidence of those who considered the tablet to be the same or better than paper was 82.5% (95% CI 74.2-90.8, p

PURPOSE:Overactive bladder syndrome is defined as urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence in the absence of urinary tract infection or another obvious pathological condition. Electronic questionnaires have been used in a few specialties with the hope of improving treatment outcomes and patient satisfaction. However, they have not been widely used in the urological field. When treating overactive bladder, the main outcome is to improve patient quality of life. The primary objective of this study was to evaluate whether electronic questionnaires would be equally accepted as or preferred to paper questionnaires. The secondary objective was to look at the preference in relation to patient age, education and iPad® tablet familiarity. MATERIALS AND METHODS:We prospectively evaluated the iList® electronic questionnaire application using a friendly iPad tablet in patients with overactive bladder who presented to the urology clinic at our institution. Each of the 80 patients who were recruited randomly completed the validated OABSS (Overactive Bladder Symptom Score) and the PPBC (Patient Perception of Bladder Condition) questionnaires in paper and electronic format on the tablet. Variables potentially associated with the outcomes of interest included demographic data, questionnaire method preference, patient response rate and iPad familiarity. We used the 2-sided Z-test to determine whether the proportion of patients who considered the tablet to be the same, better or much better than paper was significantly greater than 50%. The 2-sided chi-square test was applied to assess whether the intervention effect significantly differed among the demographic subgroups. RESULTS:A total of 80 patients 21 to 87 years old were enrolled in the study from November 2015 to August 2016. Of the patients 53% were female and 49% were 65 years or younger. The incidence of those who considered the tablet to be the same or better than paper was 82.5% (95% CI 74.2-90.8, p

We demonstrate the use of patterned aerosol adhesives to construct both planar and nonplanar 3D paper microfluidic devices. By spraying an aerosol adhesive through a metal stencil, the overall amount of adhesive used in assembling paper microfluidic devices can be significantly reduced. We show on a simple 4-layer planar paper microfluidic device that the optimal adhesive application technique and device construction style depends heavily on desired performance characteristics. By moderately increasing the overall area of a device, it is possible to dramatically decrease the wicking time and increase device success rates while also reducing the amount of adhesive required to keep the device together. Such adhesive application also causes the adhesive to form semi-permanent bonds instead of permanent bonds between paper layers, enabling single-use devices to be non-destructively disassembled after use. Nonplanar 3D origami devices also benefit from the semi-permanent bonds during folding, as it reduces the likelihood that unrelated faces may accidently stick together. Like planar devices, nonplanar structures see reduced wicking times with patterned adhesive application vs uniformly applied adhesive.

BackgroundRifampicin or rifampin (R) is a common drug used to treat inactive meningitis, cholestatic pruritus and tuberculosis (TB), and it is generally prescribed for long-term administration under regulated dosages. Constant monitoring of rifampicin is important for controlling the side effects and preventing overdose caused by chronic medication. In this study, we present an easy to use, effective and less costly method for detecting residual rifampicin in urine samples using protein (bovine serum albumin, BSA)-stabilized gold nanoclusters (BSA-Au NCs) adsorbed on a paper substrate in which the concentration of rifampicin in urine can be detected via fluorescence quenching. The intensity of the colorimetric assay performed on the paper-based platforms can be easily captured using a digital camera and subsequently analyzed.ResultsThe decreased fluorescence intensity of BSA-Au NCs in the presence of rifampicin allows for the sensitive detection of rifampicin in a range from 0.5 to 823 µg/mL. The detection limit for rifampicin was measured as 70 ng/mL. The BSA-Au NCs were immobilized on a wax-printed paper-based platform and used to conduct real-time monitoring of rifampicin in urine.ConclusionWe have developed a robust, cost-effective, and portable point-of-care medical diagnostic platform for the detection of rifampicin in urine based on the ability of rifampicin to quench the fluorescence of immobilized BSA-Au NCs on wax-printed papers. The paper-based assay can be further used for the detection of other specific analytes via surface modification of the BSA in BSA-Au NCs and offers a useful tool for monitoring other diseases.

BackgroundRifampicin or rifampin (R) is a common drug used to treat inactive meningitis, cholestatic pruritus and tuberculosis (TB), and it is generally prescribed for long-term administration under regulated dosages. Constant monitoring of rifampicin is important for controlling the side effects and preventing overdose caused by chronic medication. In this study, we present an easy to use, effective and less costly method for detecting residual rifampicin in urine samples using protein (bovine serum albumin, BSA)-stabilized gold nanoclusters (BSA-Au NCs) adsorbed on a paper substrate in which the concentration of rifampicin in urine can be detected via fluorescence quenching. The intensity of the colorimetric assay performed on the paper-based platforms can be easily captured using a digital camera and subsequently analyzed.ResultsThe decreased fluorescence intensity of BSA-Au NCs in the presence of rifampicin allows for the sensitive detection of rifampicin in a range from 0.5 to 823 µg/mL. The detection limit for rifampicin was measured as 70 ng/mL. The BSA-Au NCs were immobilized on a wax-printed paper-based platform and used to conduct real-time monitoring of rifampicin in urine.ConclusionWe have developed a robust, cost-effective, and portable point-of-care medical diagnostic platform for the detection of rifampicin in urine based on the ability of rifampicin to quench the fluorescence of immobilized BSA-Au NCs on wax-printed papers. The paper-based assay can be further used for the detection of other specific analytes via surface modification of the BSA in BSA-Au NCs and offers a useful tool for monitoring other diseases.

OBJECTIVES: Existing electronic data capture options are often financially unfeasible in resource-poor settings or difficult to support technically in the field. To help facilitate large-scale multicenter studies in sub-Saharan Africa, the African Partnership for Chronic Disease Research (APCDR) has developed an open-source electronic questionnaire (EQ). STUDY DESIGN AND SETTING: To assess its relative validity, we compared the EQ against traditional pen-and-paper methods using 200 randomized interviews conducted in an ongoing type 2 diabetes case-control study in South Africa. RESULTS: During its 3-month validation, the EQ had a lower frequency of errors (EQ, 0.17 errors per 100 questions; paper, 0.73 errors per 100 questions; P-value ≤0.001), and a lower monetary cost per correctly entered question, compared with the pen-and-paper method. We found no marked difference in the average duration of the interview between methods (EQ, 5.4 minutes; paper, 5.6 minutes). CONCLUSION: This validation study suggests that the EQ may offer increased accuracy, similar interview duration, and increased cost-effectiveness compared with paper-based data collection methods. The APCDR EQ software is freely available (https://github.com/apcdr/questionnaire).

We present a technique for simulating plastic deformation in sheets of thin materials, such as crumpled paper, dented metal, and wrinkled cloth. Our simulation uses a framework of adaptive mesh refinement to dynamically align mesh edges with folds and creases. This framework allows efficient modeling of sharp features and avoids bend locking that would be otherwise caused by stiff in-plane behavior. By using an explicit plastic embedding space we prevent remeshing from causing shape diffusion. We include several examples demonstrating that the resulting method realistically simulates the behavior of thin sheets as they fold and crumple. Copyright © ACM 2013.

No industry has been affected by environmental social movements as much, in so short a time, and on such a wide geographical scale, as pulp and paper manufacturing. Environmental social movements have had a profound influence on the industry since the mid- to late 1980s. In just a few years, “state of the art” pulping and bleaching has become more environmentally friendly. Manufacturers around the world have spent billions of US dollars adopting new technologies, modifying old ones, and developing local innovations to meet rising environmental demands, expectations, and regulations. Additional millions of US dollars have been spent by public and private institutions on research, development, and testing of new nvironmental processes and technologies for the pulp and paper industry (cf. API 1992; Porter and Linde 1995). The transformation is incomplete -- many environmental problems remain -- but nonetheless profound. All of this can be attributed at least initially to the efforts and influence of environmental social movements.

Synthetic luteinizing hormone-releasing hormone (LH-RH) lost both its immunore-activity and hormonal activity on incubation with hypothalamic or cerebrocortical slices or homogenates. This inactivation was shown to be due to degradation of the decapeptide by soluble enzyme(s) present in the 100,000 × g supernatant fraction of the homogenates. The supernatant derived from one rat hypothalamus was capable of destroying 1 μg of exogenous LH-RH within 5 min. The hexapeptide pGlu-His-Trp-Ser-Tyr-Gly was identified as the major radioactive breakdown product of [pGlu-3-3H] LH-RH, and tentative evidence for the formation of the tetrapeptide Leu-Arg-Pro-Gly-NH2 was obtained by sequential electrophoresis and paper chromatography. These findings suggest that the Gly-Leu bond may be the preferred site of cleavage. © 1974.

Synthetic luteinizing hormone-releasing hormone (LH-RH) lost both its immunore-activity and hormonal activity on incubation with hypothalamic or cerebrocortical slices or homogenates. This inactivation was shown to be due to degradation of the decapeptide by soluble enzyme(s) present in the 100,000 × g supernatant fraction of the homogenates. The supernatant derived from one rat hypothalamus was capable of destroying 1 μg of exogenous LH-RH within 5 min. The hexapeptide pGlu-His-Trp-Ser-Tyr-Gly was identified as the major radioactive breakdown product of [pGlu-3-3H] LH-RH, and tentative evidence for the formation of the tetrapeptide Leu-Arg-Pro-Gly-NH2 was obtained by sequential electrophoresis and paper chromatography. These findings suggest that the Gly-Leu bond may be the preferred site of cleavage. © 1974.

1. 1. The metabolism of [8-14C]adenosine was examined in human erythrocytes and erythrocyte lysates. 2. 2. The metabolism of [8-14C]adenosine in erythrocytes is largely dependent upon its concentration. 3. 3. Adenosine deaminase and adenosine kinase activities were assayed in crude erythrocyte lysates. No adenosine phosphorylase activity was detected. 4. 4. Adenosine deaminase exhibited a Km for adenosine of 4 · 10-5 M. Substrate inhibition of the enzyme was exhibited at concentrations of adenosine greater than 2 · 10-4 M. No inhibition of deaminase activity by equimolar or greater concentration of AMP, ADP, ATP, GDP, GTP, Pi, guanylic acid or 2,3-diphosphoglycerate was noted, but 20 % inhibition by high concentrations of adenine and inosine was observed. 5. 5. Adenosine kinase required ATP (Km = 4 · 10-4 M), adenosine (Km = 1.9 · 10-6 M), and Mg2+ for activity. No substrate inhibition by adenosine occurred at concentrations 20 times its Km. Adenosine 5′-triphosphate and Mg2+ were inhibitory at concentrations greater than 1.25 mM and 0.50 mM, respectively. The reaction of ATP with adenosine kinase was competitively inhibited by AMP, ADP, guanylic acid, GDP, IMP, and adenine. Adenosine 5′-triphosphate was variably replaceable as the phosphate donor by a wide range of triphosphates. © 1971.

1. 1. The metabolism of [8-14C]adenosine was examined in human erythrocytes and erythrocyte lysates. 2. 2. The metabolism of [8-14C]adenosine in erythrocytes is largely dependent upon its concentration. 3. 3. Adenosine deaminase and adenosine kinase activities were assayed in crude erythrocyte lysates. No adenosine phosphorylase activity was detected. 4. 4. Adenosine deaminase exhibited a Km for adenosine of 4 · 10-5 M. Substrate inhibition of the enzyme was exhibited at concentrations of adenosine greater than 2 · 10-4 M. No inhibition of deaminase activity by equimolar or greater concentration of AMP, ADP, ATP, GDP, GTP, Pi, guanylic acid or 2,3-diphosphoglycerate was noted, but 20 % inhibition by high concentrations of adenine and inosine was observed. 5. 5. Adenosine kinase required ATP (Km = 4 · 10-4 M), adenosine (Km = 1.9 · 10-6 M), and Mg2+ for activity. No substrate inhibition by adenosine occurred at concentrations 20 times its Km. Adenosine 5′-triphosphate and Mg2+ were inhibitory at concentrations greater than 1.25 mM and 0.50 mM, respectively. The reaction of ATP with adenosine kinase was competitively inhibited by AMP, ADP, guanylic acid, GDP, IMP, and adenine. Adenosine 5′-triphosphate was variably replaceable as the phosphate donor by a wide range of triphosphates. © 1971.