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In this work, the design of a microfluidic paper-based analytical device (μPAD) for the quantification of nitrate in urine samples was described. Nitrate monitoring is highly relevant due to its association to some diseases and health conditions. The nitrate determination was achieved by combining the selectivity of the nitrate reductase enzymatic reaction with the colorimetric detection of nitrite by the well-known Griess reagent. For the optimization of the nitrate determination μPAD, several variables associated with the design and construction of the device were studied. Furthermore, the interference of the urine matrix was evaluated, and stability studies were performed, under different conditions. The developed μPAD enabled us to obtain a limit of detection of 0.04 mM, a limit of quantification of 0.14 mM and a dynamic concentration range of 0.14–1.0 mM. The designed μPAD proved to be stable for 24 h when stored at room temperature in air or vacuum atmosphere, and 60 days when stored in vacuum at −20 °C. The accuracy of the nitrate μPAD measurements was confirmed by analyzing four certified samples (prepared in synthetic urine) and performing recovery studies using urine samples.

Leukocyte esterase (LE) is a useful marker that can be used in establishing a diagnosis of urinary tract infections (UTIs). The development of a UTI diagnostic method with quantitative determinations of biomarkers across all age groups is becoming more important. In this report, microfluidic resistance sensors based on silver ink (Ag ink) and silver ink mixed with ZnO nanoparticles (Ag-ZnO ink) were synthesized and coated on cellulose paper, namely LE-Ag-μPADs and LE-Ag-ZnO-μPADs, respectively, for the sensitive detection of LE. The microfluidic design increases the precision of data and further allows for quantitative determination and early detection of LE in human urine. The quantification of LE relies on the change in the resistance readout coating with Ag ink as well as Ag-ZnO ink in the detection zone. A mixture of 3-(N-tosyl-l-alaninyloxy)-5-phenylpyrrole (PE) and 1-diazo-2-naphthol-4-sulfonic acid (DAS) was deposited in the sample zone to selectively recognize LE, and the resulting nonconductive products, i.e., azo compounds, further reacted with the Ag ink and Ag-ZnO ink to increase resistance. The quantitative detectable LE concentrations between 2 to 32 (×5.2 U mL-1), i.e. ≈12 to 108 μg L-1, cover the commercial dipstick range of trace, +1 and +2. The minimum detectable concentration of LE in urine was 1 (×5.2 U mL-1). The lower concentrations of LE detectable by LE-Ag-μPADs (1-8 × 5.2 U mL-1) are below the value achieved with the ELISA LE kit. Urine samples from inpatients with indwelling urinary catheters were used, and the LE levels measured by the present device were highly correlated with those determined by a commercial urine analyser.

Bladder cancer is the fourth most common cancer in men, and it is becoming a prevalent malignancy. Most of the regular clinical examinations are prompt evaluations with cystoscopy, renal function testing, which require high-precision instrument, well-trained operators, and high cost. In this study, a microfluidic paper-based analytical device (μPAD) was fabricated to detect nuclear matrix protein 22 (NMP22) and bladder cancer antigen (BTA) from the urine samples. Urine samples were collected from 11 bladder cancer patients and 10 well-beings as experiment and control groups, respectively, to verify the working efficiency of μPAD. A remarkable checkout efficiency of up to 90.91% was found from the results. Meanwhile, this method is feasible for home-based self-detection from urine samples within 10 min for the total process, which provides a new way for quick, economical, and convenient tumor diagnosis, prognosis evaluation, and drug response.

Proteinuria is a condition in which an excessive amount of protein is excreted in urine. It is, among others, an indicator of kidney disease or risk of cardiovascular disease. Rapid and reliable diagnosis and monitoring of proteinuria is of great importance for both patients and their physicians. For that reason, a paper-based sensor for proteinuria diagnosis was designed, optimized, and validated utilizing smartphone-assisted signal acquisition. In the first step, a few commonly employed protein assays were optimized and compared in terms of analytical performance on paper matrix. The tetrabromophenol blue method was selected as the one providing a sufficiently low limit of detection (39 mg·L−1) on the one hand and appropriate long-term stability (up to 3 months) on the other hand. The optimized assay was employed for protein-to-creatinine ratio (PCR) determination on a single paper-based sensor. For both analytes the linear ranges were within the clinically relevant range. The analytical usefulness of the developed sensors was demonstrated by a PCR recovery study in artificial urine. The obtained PCR recoveries were from ca. 80 to 150%.

In recent years, microfluidic lab-on-paper devices have emerged as a rapid and low-cost alternative to traditional laboratory tests. Additionally, they were widely considered as a promising solution for point-of-care testing (POCT) at home or regions that lack medical infrastructure and resources. This review describes important advances in microfluidic lab-on-paper diagnostics for human health monitoring and disease diagnosis over the past five years. The review commenced by explaining the choice of paper, fabrication methods, and detection techniques to realize microfluidic lab-on-paper devices. Then, the sample pretreatment procedure used to improve the detection performance of lab-on-paper devices was introduced. Furthermore, an in-depth review of lab-on-paper devices for disease measurement based on an analysis of urine samples was presented. The review concludes with the potential challenges that the future development of commercial microfluidic lab-on-paper platforms for human disease detection would face.

The Phenylketonuria (PKU) is an inborn defect of phenylalanine (Phe) metabolism, in which Phe accumulated in the blood causing alterations at the central nervous system. Therefore, the detection of PKU is very important for the early diagnosis of PKU patients. However, existing tests for PKU are time-consuming and require high-resource laboratories. In this study, a novel paper-based biosensor based on phenylalnine ammonia lyase (PAL) hybrid nanoflowers was constructed that provides a semi-quantitative output of the concentration of Phe from urine samples. PAL@Ca3(PO4)2 hybrid nanoflowers (PAL@NF) were first prepared using PAL and Ca2+. Synthesis conditions of the PAL@NF on the formation of the PAL@NF were optimized. The PAL@NF exhibited 90% activity recovery under optimal condition. Compared with free PAL, the PAL@NF displayed good storage stability and increased tolerance to proteolysis. After five consecutive operating cycles, the PAL@NF still retained 73% of its initial activity, indicating excellent reusability. Furthermore, the paper-based biosensor was able to detect Phe concentration in urine samples, and exhibited good linearity to the Phe concentrations in the range from 60 to 2400 μM and the response time was only about 10 min. Therefore, the paper-based biosensor can be a promising candidate as a biosensor for the detection of PKU.

Made available in DSpace on 2020-12-12T02:09:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-03 In this study, the direct analysis of doping agents in urine samples with no sample preparation by a modified paper spray mass spectrometry (PS-MS) methodology has been demonstrated for the first time. We have described a paper surface treatment with trichloromethylsilane using a gas-phase reaction to increase the ionization of target compounds. This approach was applied for the analysis of two classes of banned substances in urine samples: anabolic agents (trenbolone and clenbuterol) and diuretics (furosemide and hydrochlorothiazide). Under optimized conditions, the developed methods presented satisfactory repeatability, and an analysis of variance showed linearity without lack-of-fit. Highly sensitive detections as low as sub-nanogram per milliliter levels, which is below the minimum required performance levels proposed by the World Anti-Doping Agency, have been reached using the hydrophobic PS-MS analysis without any preconcentration and cleanup step. Department of Chemistry and Biochemistry Ohio State University, 100 West 18th Avenue Institute of Chemistry Department of Analytical Chemistry São Paulo State University (UNESP), Rua Professor Francisco Degni 55 ,P.O. Box 355 Institute of Chemistry Department of Analytical Chemistry São Paulo State University (UNESP), Rua Professor Francisco Degni 55 ,P.O. Box 355

Rapid analysis of metabolites in biofluids is of great importance for disease diagnosis or new-born disease screening. Herein, we introduce an agarose hydrogel conditioning method to enhance the performance of paper spray ionization mass spectrometry. With facile and fast hydrogel conditioning, the signal intensity of therapeutic drugs spiked in urine was 5 to 15 fold higher than that in direct paper spray ionization mass spectrometry analysis. Consequently, the sensitivity of metabolites in urine was improved via hydrogel conditioning, resulting in 9 to 15 fold decrease in the possibility of detection (POD) levels. These results show that agarose hydrogel conditioning coupled with paper spray ionization mass spectrometry could serve as a facile ionization method for ambient mass spectrometry, which might be useful in fast screening of metabolites and therapeutic drugs in raw biofluids.

Non-invasive diagnosis on biological liquid samples, such as urine, sweat, saliva, and tears, may allow patients to evaluate their health by themselves. To obtain accurate diagnostic results, target liquid must be precisely sampled. Conventionally, urine sampling using filter paper can be given as an example sampling, but differences in the paper structure can cause variations in sampling volume. This paper describes precise liquid sampling using synthetic microfluidic papers, which are composed of obliquely combined micropillars. Sampling volume accuracy was investigated using different designs and collection methods to determine the optimal design and sample collecting method. The optimized protocol was followed to accurately measure potassium concentration using synthetic microfluidic paper and a commercially available densitometer, which verified the usefulness of the synthetic microfluidic papers for precision sampling.

In this study, a slug-flow microextraction (SFME) coupled with paper spray mass spectrometry (PS-MS) method was developed for rapid and on-site analysis of trace amphetamine-type illicit drugs including amphetamine (AM), methamphetamine (MA) and 3,4-methylenedioxy-N-methylamphetamine (MDMA) in complex biological samples such as whole blood and raw urine. The method involved the application of SFME for rapid extraction of trace amphetamine-type illicit drugs from whole blood and raw urine samples, followed by PS for direct MS analysis under ambient and open-air conditions. The experimental parameters including extraction solvent, extraction cycle, high voltage, and spray solvent, etc., were all investigated, and the optimized conditions showed an enhanced sensitivity of 1–2 order of magnitudes compared with PS-MS. The method showed good linearity, with correlation coefficient values (r) of no less than 0.9979 for analysis of AM, MA, and MDMA in human whole blood and raw urine without additional sample pretreatments. The limits of detection and quantification were 0.01–0.05 ng/mL and 0.05–0.2 ng/mL, respectively. Satisfactory recoveries were also obtained, with 74.2–94.9% for whole blood and 80.2–103.6% for raw urine, respectively. All of our experimental results demonstrated that SFME-PS-MS showed great potential for rapid, on-site, in situ, and high-throughput screening of amphetamine-type illicit drugs in various biological samples.

Aim: Since 2014, enzyme replacement therapy (ERT) has been available for treatment of Morquio A syndrome. During clinical trials, urinary keratan sulfate (KS) has been a useful biomarker and showed a marked decrease in patients on ERT, demonstrating therapy efficacy. Unfortunately, quantitative urinary KS testing is not widely available in biochemical genetics laboratories for efficient monitoring and follow-up of treated patients. Materials & methods: A tandem mass spectrometry methodology was devised to analyze KS disaccharides and creatinine in urine specimens collected on filter paper. Results: All Morquio A patients presented abnormal results pretreatment compared with reference values. Conclusion: This collection procedure can be performed by patients at home and filter papers sent by regular mail to a specialized laboratory, facilitating follow-up of patients.

This paper presents a whole-cell biosensor that operates in conjunction with a smartphone-based fluorescence diagnostic system on a paper device to monitor the concentration of gold ions in human urine. The heavy metal-tolerant bacteria Cupriavidus metallidurans was genetically engineered for use as a chassis in a red fluorescent protein (RFP)-based microbial sensor. The biosensor is highly sensitive to gold ions, with a detection limit of 110 nM. The proposed smartphone-based analysis system provides a user-friendly approach to design tools of personal health monitoring for reporting the presence of gold ions in human urine.

Made available in DSpace on 2018-12-11T17:34:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-02 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In this paper, we describe a validated paper-based microfluidic analytical device for the simultaneous quantification of two important biomarkers of renal function in urine. This paper platform provides an inexpensive, simple, and easy to use colorimetric method for the quantification of creatinine (CRN) and uric acid (UA) in urine samples. The microfluidic paper-based analytical device (μPAD) consists of a main channel with three identical arms, each containing a circular testing zone and a circular uptake zone. Creatinine detection is based on the Jaffé reaction, in which CRN reacts with picrate to form an orange-red product. Uric acid quantification is based on the reduction of Fe3+ to Fe2+ by UA, which is detected in a colorimetric reaction using 1,10-phenanthroline. Under optimum conditions, obtained through chemometrics, the concentrations of the analytes showed good linear correlations with the effective intensities, and the method presented satisfactory repeatability. The limits of detection and the linear ranges, respectively, were 15.7 mg L−1 and 50–600 mg L−1 for CRN and 16.5 mg L−1 and 50–500 mg L−1 for UA. There were no statistically significant differences between the results obtained using the μPAD and a chromatographic comparative method (Student's t-test at 95% confidence level). Instituto de Química Universidade Estadual Paulista “Julio de Mesquita Filho”- UNESP, R. Prof. Francisco Degni 55, P.O. Box 355 Instituto de Química de São Carlos Universidade de São Paulo, Av. Trabalhador São-carlense, 400 Instituto de Química Universidade Estadual Paulista “Julio de Mesquita Filho”- UNESP, R. Prof. Francisco Degni 55, P.O. Box 355 CNPq: 132646/2014-5 CAPES: 2014/17749-7 FAPESP: 2015/21733-1 CNPq: 308788/2015-0

Simple, low-cost and portable microfluidic paper-based analytical devices (μPADs) for determination of creatinine in urine samples were developed. The methodology was based on Jaffé reaction between the creatinine and picric acid in alkaline conditions, generating a colorimetric creatinine-alkaline picrate complex. The product exhibits an orange color that is clearly visible on the μPADs. The color intensity of the complex, which is indicative of the concentration of creatinine, is then quantitatively determined using ImageJ software. Various experimental parameters were optimized to achieve the best performance of the μPADs. Under the optimum conditions, a wide linear range was obtained in the range of 0.2 - 1 mM with a limit of detection and limit of quantitation of 0.08 and 0.26 mM, respectively. The accuracy of the proposed method was in good agreement with the standard Jaffé method. Finally, the developed devices were successfully applied for the determination of creatinine in urine samples.

Bisphenol A (BPA) is an endocrine disruptor frequently detected in human biofluids. Dermal absorption of BPA from thermal paper receipts occurs but BPA pharmacokinetics following dermal exposure is not understood. To compare the pharmacokinetics of dermal and dietary BPA exposure, six male participants handled simulated receipts containing relevant levels of BPA (isotope-labeled BPA-d16) for 5 min, followed by hand-washing 2 h later. Urine (0–48 h) and serum (0–7.5 h) were monitored for free and total BPA-d16. One week later, participants returned for a dietary administration with monitoring as above. One participant repeated the dermal administration with extended monitoring of urine (9 days) and serum (2 days). After dietary exposure, urine total BPA-d16 peaked within 5 h and quickly cleared within 24 h. After dermal exposure, cumulative excretion increased linearly for 2 days, and half the participants still had detectable urinary total BPA-d16 after 1 week. The participant repeating the dermal exposur...

Background:Newborn screening (NBS) is an established screening procedure in many countries worldwide, aiming at the early detection of inborn errors of metabolism. For decades, dried blood spots have been the standard specimen for NBS. The procedure of blood collection is well described and standardized and includes many critical pre-analytical steps. We examined the impact of contamination of some anticipated common substances on NBS results obtained from dry spot samples. This possible pre-analytical source of uncertainty has been poorly examined in the past.Methods:Capillary blood was obtained from 15 adult volunteers and applied to 10 screening filter papers per volunteer. Nine filter papers were contaminated without visible trace. The contaminants were baby diaper rash cream, baby wet wipes, disinfectant, liquid infant formula, liquid infant formula hypoallergenic (HA), ultrasonic gel, breast milk, feces, and urine. The differences between control and contaminated samples were evaluated for 45 NBS quantities. We estimated if the contaminations might lead to false-positive NBS results.Results:Eight of nine investigated contaminants significantly altered NBS analyte concentrations and potentially caused false-positive screening outcomes. A contamination with feces was most influential, affecting 24 of 45 tested analytes followed by liquid infant formula (HA) and urine, affecting 19 and 13 of 45 analytes, respectively.Conclusions:A contamination of filter paper samples can have a substantial effect on the NBS results. Our results underline the importance of good pre-analytical training to make the staff aware of the threat and ensure reliable screening results.

In Portugal, the potent paralytic shellfish toxins (PSTs) have appeared irregularly since the onset of a national monitoring program for marine biotoxins in 1986. In years where high contamination levels were attained in bivalves, sporadic cases of human poisonings have been recorded, as in 1994 and 2007. The reappearance of high contamination levels led to the appearance of new cases during the autumn of 2018. This study details toxin ingestion, symptomatology and toxin elimination and metabolization in the fluids of two patients, who ingested mussels from the Portuguese southwest coast and required hospitalization due to the severity of symptoms. Toxin elimination was confirmed by ELISA in plasma and urine samples. In mussel samples, the toxin profile obtained by HPLC-FLD displayed a wide diversity of toxins, typical of Gymnodinum catenatum ingestion. However, in the urine samples, the toxin profile was reduced to B1 and dcSTX. Abundant compounds in mussels having an O-sulphate at C11, such as C1+2 and dcGTX2+3, were absent in urine. In plasma, PSTs were not detected by HPLC-FLD. Calculated toxin ingestion, resulting from consumption of an estimated 200-g portion, was in the range of 104–120 μg STX eq./kg b. w., Graphical abstract Image 1, Highlights • Since 1986 Gymnodinium catenatum contaminates irregularly bivalves in Portugal with PSTs. • Acute neurological symptomology, such as paraesthesias, has often required hospitalization. • During an episode in October 2018, toxins in fluids of two victims and toxin ingestion were studied. • Preliminary confirmation was done by ELISA in serum and urine. • PSP toxins with an O-sulphate at C11, abundant in mussels, were absent in urine.

Urine contains multiple water-soluble hormones, which are valuable non-invasive biomarkers for the monitoring of reproductive status and health. An effective method for drying urine on filter paper was previously developed to preserve wildlife urine samples where electrical equipment was not available for this; however, the stability of samples preserved in this way remains to be verified. Here, we developed and validated a method to elute multiple water-soluble reproductive hormones from filter paper that had been stored for an extended period of time. Aliquots of urine from chimpanzees were adsorbed on filter papers, air dried and stored for 1 year at room temperature. Estrone-3-conjugate (E1C), pregnanediol-3-glucuronide (PdG), estriol-3-glucuronide (E3G), and chorionic gonadotropin (CG) were eluted into deionized water from the filter papers and measured using enzyme immunoassays (EIAs). The mean recoveries of E1C, PdG, and creatinine from filter papers stored for 1 year were 69.5%, 128.7%, and 83.8%, respectively. The profiles of E1C and PdG from preserved filter papers significantly correlated with those derived from a direct analysis of the frozen urine of menstruating chimpanzees. We detected E3G and CG from 1-year-old filter papers for urine collected during early pregnancy, but the recovery of E3G was low and CG profiles did not correlate with those of the original frozen urine samples. The method proposed here for the elution and measurement of reproductive hormones in urine preserved for a long period of time on filter paper provides a practical and simple way to monitor the reproductive status of chimpanzees. We propose that this method can also be utilized in field studies of other wild nonhuman primates.

Although paper-based colorimetric sensors utilizing enzymatic reactions are well suited for real-field diagnosis, their widespread use is hindered by signal blurring at the detection spot due to the action of capillary forces on the liquid and the corresponding membrane. In this study, we eliminated signal losses commonly observed during enzyme-mediated colorimetric sensing and achieved pattern-free quantitative analysis of glucose and uric acid by mixing enzymes and color-forming reagents with chitosan oligosaccharide lactate (COL), which resulted in perfectly focused colorimetric signals at the detection spot, using asymmetric flow induced by changing the flow rate of the COL-treated paper. The targets were calibrated with 0-500 mg/dL of glucose and 0-200 mg/dL of uric acid, and the limit of detection was calculated to be 0.6 and 0.03 mg/dL, respectively. In human urine, the correlation has a high response between the measured and spiked concentrations, and the stability of the enzyme mixture including COL increased by 41% for glucose oxidase mixture and 29% for uricase mixture, compared to the corresponding mixtures without COL. Thus, the color focusing and pattern-free sensor, which have the advantages of easy fabrication, easy handling, and high stability, should be applied to real-field diagnosis.

Cell-free transcription-translation systems have great potential for biosensing, yet the range of detectable chemicals is limited. Here we provide a workflow to expand the range of molecules detectable by cell-free biosensors through combining synthetic metabolic cascades with transcription factor-based networks. These hybrid cell-free biosensors have a fast response time, strong signal response, and a high dynamic range. In addition, they are capable of functioning in a variety of complex media, including commercial beverages and human urine, in which they can be used to detect clinically relevant concentrations of small molecules. This work provides a foundation to engineer modular cell-free biosensors tailored for many applications.

A rapid and direct paper spray ionization/mass spectrometry (PSI/MS) method was developed for quantitative analysis of ephedrine, pseudoephedrine, norpseudoephedrine, and methylephedrine in human urine. This method involves the use of a triangular filter paper and high-resolution mass spectrometry, where the molecular ions of ephedrines were generated by applying high voltage after loading the spray solvent to the paper which urine sample was pre-loaded. Small amounts (2μL) of urine spiked with an internal standard were directly analyzed for ephedrines. The PSI/MS method was validated for linearity, within- and between-run precision, accuracy, and limit of detection. The results showed good linearity (R(2)≥0.9928) and acceptable precision and accuracy. Furthermore, the accuracy of the method was assessed by analyzing a blind urine sample from World Anti-Doping Agency and comparing the measured concentrations with the nominal concentrations. This test resulted in accuracies ranging from 96.4 to 106.1%, indicating that the PSI/MS method has the potential to be an alternative technique for the fast quantitation of ephedrines in doping control analysis.

A new paper platform was developed for the colorimetric detection of creatinine. The filter paper was coated with 3-propylsulfonic acid trimethoxysilane and used as the platform. Creatinine in a cationic form was extracted onto the paper via an ion-exchange mechanism and detected through the Jaffé reaction, resulting in a yellow-orange color complex. The color change on the paper could be observed visually, and the quantitative detection of creatinine was achieved through monitoring the color intensity change. The color intensity of creatinine complexes on the paper platform as a function of the creatinine concentration provided a linear range for creatinine detection in the range of 10 - 60 mg L(-1) and a detection limit of 4.2 mg L(-1). The accuracy of the proposed paper-based method was comparable to the conventional standard Jaffé method. This paper platform could be applied for simple and rapid detection of creatinine in human urine samples with a low consumption of reagent.

Background: Bisphenol A (BPA) is a high-production-volume chemical associated with a wide range of health outcomes in animal and human studies. BPA is used as a developer in thermal paper products, including cash register receipt paper; however, little is known about exposure of cashiers to BPA and alternative compounds in receipt paper. Objective: We determined whether handling receipt paper results in measurable absorption of BPA or the BPA alternatives bisphenol S (BPS) and 4-hydroxyphenyl 4-isoprooxyphenylsulfone (BPSIP). Methods: Cashiers (n = 77) and non-cashiers (n = 25) were recruited from the Raleigh–Durham–Chapel Hill region of North Carolina during 2011–2013. Receipts were analyzed for the presence of BPA or alternatives considered for use in thermal paper. In cashiers, total urine and serum BPA, BPS, and BPSIP levels in post-shift samples (collected ≤ 2 hr after completing a shift) were compared with pre-shift samples. Levels of these compounds in urine from cashiers were compared to levels in urine from non-cashiers. Results: Each receipt contained 1–2% by weight of the paper of BPA, BPS, or BPSIP. The post-shift geometric mean total urinary BPS concentration was significantly higher than the pre-shift mean in 33 cashiers who handled receipts containing BPS. The mean urine BPA concentrations in 31 cashiers who handled BPA receipts were as likely to decrease as to increase after a shift, but the mean post-shift concentrations were significantly higher than those in non-cashiers. BPSIP was detected more frequently in the urine of cashiers handling BPSIP receipts than in the urine of non-cashiers. Only a few cashiers had detectable levels of total BPA or BPS in serum, whereas BPSIP tended to be detected more frequently. Conclusions: Thermal receipt paper is a potential source of occupational exposure to BPA, BPS, and BPSIP. Citation: Thayer KA, Taylor KW, Garantziotis S, Schurman SH, Kissling GE, Hunt D, Herbert B, Church R, Jankowich R, Churchwell MI, Scheri RC, Birnbaum LS, Bucher JR. 2016. Bisphenol A, bisphenol S, and 4-hydro​xyphenyl 4-isopro​oxyphenyl​sulfone (BPSIP) in urine and blood of cashiers. Environ Health Perspect 124:437–444; http://dx.doi.org/10.1289/ehp.1409427

We report a paper-based assay platform for the detection of the kidney disease marker Trefoil Factor 3 (TFF3) in human urine. The sensor is based on a quantitative metalloimmunoassay that can determine TFF3 concentrations via electrochemical detection of environmentally stable silver nanoparticle (AgNP) labels attached to magnetic microbeads via a TFF3 immunosandwich. The paper electroanalytical device incorporates two preconcentration steps that make it possible to detect concentrations of TFF3 in human urine at the low end of the target TFF3 concentration range (0.03-7.0 μg mL(-1)). Importantly, the paper device provides a level of accuracy for TFF3 determination in human urine equivalent to that of a commercial kit. The paper sensor has a dynamic range of ∼2.5 orders of magnitude, only requires a simple, one-step incubation protocol, and is fast, requiring only 10 min to complete. The cost of the materials at the prototypic laboratory scale, excluding reagents, is just US$0.42.