Paper Analytical Device Research Articles

Beyond wax printing: The future of paper analytical device fabrication

Many microfluidic “lab on paper” devices have been demonstrated for point-of-use applications, but scalable fabrication methods are necessary for these devices to make it past the proof-of-concept stage and become viable commercial products. Commercially available wax printers such as the Xerox ColorQube presented a near-ideal compromise between cost, ease of prototyping, and throughput, but in 2016, these printers were discontinued, and now, alternative methods are needed. In this review, we survey current paper analytical device (PAD) fabrication methods through the lens of scalability, focusing on the tradeoffs between resolution, ease of prototyping, cost, and throughput. Categories discussed include handmade, semi-automated, batch, laboratory-based, printer-based, and roll-to-roll fabrication methods. Hand-, batch-, semi-automated, and laboratory-based fabrication methods suffer from low throughput and high hands-on labor requirements. Roll-to-roll methods are high throughput but costly, while printer-based methods offer a compromise between cost and throughput. By highlighting the comparative merits of existing methods, we hope to offer insight into what makes a method “scalable” or “manufacturable.”

Ni-NTA resin-based multiplexed origami device for highly efficient sensing of allergen-specific IgE

Food allergy diagnosis requires a highly sensitive detection of allergen-specific immunoglobulin E (sIgE) in the serum. Enzyme-linked immunosorbent assay (ELISA) is a classical method widely used for sIgE detection but had to rely on costly and time-consuming assay procedures, skilled technicians, and bulky equipment. Here, a multiplexed origami paper analytical device (moPAD) that is hexahistidine-tagged and integrated with a nitrilotriacetic acid-functionalized surface with nickel (Ni-NTA) was developed to achieve low-cost and high-efficiency immunosensing of multiple allergen-specific IgEs in serum. The major oyster allergens, Cra a 1, Cra a 2, and Cra a 4, were used to detect sIgE in human serum. The feasibility of the moPAD-based immunosensing strategy was successfully demonstrated by desirable sensitivities for multiple targets. The detection results of moPAD for 72 serum samples were 100% consistent with clinical test results, while 69 of these results showed no significant differences from ELISA results, demonstrating the accuracy and stability of this method. A fully integrated moPAD reduces detection time and achieves highly sensitive quantification using a simple smartphone-based readout. Efficient allergen modification of paper devices has great applicability in allergen component-resolved diagnostics. The implementation of moPAD can make the process of allergy diagnosis simpler for patients, physicians, and healthcare systems alike.

Distance-based paper analytical device for the determination of dissolved inorganic carbon concentration in freshwater

Dissolved inorganic carbon (DIC) levels in freshwaters play a key role in the equilibrium of the carbon cycle between the atmosphere, water and living beings. Standard classical methods for DIC determination generally involve bulky and expensive equipment used in centralized laboratories, resulting in time-consuming processes that do not allow for adequate monitoring in the field. In order to address this challenge, we have developed a distance-based paper analytical device (PAD) for on-site determination of DIC in water. The portable, cost-effective and easy-to-use device was based on the miniaturization and integration of a classical acid-base colorimetric titration on a paper channel, enabling an accurate determination of DIC in less than 20 min. The length of the blue colored line in the detection channel after being filled with the sample was related to the DIC concentration in the sample. The reagent solution used to modify the titration channel was optimized so that DIC concentrations in the range 50–1000 mg L−1 could be measured. The long-term stability of the paper-based device was also evaluated, demonstrating a working stability for more than 70 days after their fabrication, an important characteristic for in-the-field analysis. Finally, the PAD was validated with different water samples, i.e. tap water, commercial bottled drinking water and water samples from a mine, with excellent agreement between the results obtained from the PAD and the standard method. This demonstrates the high potential of the proposed paper analytical device to quantify DIC in situ by minimally-trained personnel without the need for peripheral equipment, which represents an important advance compared to the current limited analysis systems.

Rapid detection of three mycotoxins in animal feed materials using competitive ELISA-based origami microfluidic paper analytical device (μPAD).

We report the development of a competitive ELISA-based origami microfluidic paper-based analytical device (μPAD) for the detection of mycotoxins in animal feed material. The μPAD was patterned using the wax printing technique with the design of a testing pad in the middle and two absorption pads at the side. Anti-mycotoxin antibodies were effectively immobilized on chitosan-glutaraldehyde-modified sample reservoirs in the μPAD. The determination of zearalenone, deoxynivalenol, and T-2 toxin in corn flour was successfully achieved by performing competitive ELISA on the μPAD in 20min. Colorimetric results were easily distinguished by the naked eye with a detection limit of 1µg/mL for all three mycotoxins. The μPAD integrated with competitive ELISA holds potential for practical applications in thelivestock industry for rapid, sensitive, and cost-effective detection of different mycotoxins in animal feed materials.

Threaded 3D microfluidic paper analytical device-based ratiometric fluorescent sensor for background-free and visual detection of organophosphorus pesticides

With the increasing concerns of food safety and environmental protection, it is desirable to develop reliable, effective, and portable sensors for detection of organophosphorus pesticides (OPs). Here, a cascade reaction system integrated with threaded 3D microfluidic paper analytical device (3D μPAD) was firstly developed for background-free and visual detection of OPs in agricultural samples. Butyrylcholinesterase (BChE) hydrolyzed acetylcholine into thiocholine (TCh), which reduced MnO2 nanosheets into Mn2+. With addition of OPs, BChE activity was irreversibly inhibited, and the generation of TCh and the reduction of MnO2 nanosheets were prevented. Then the remaining MnO2 nanosheets oxidized o-phenylenediamine into 2,3-diaminophenazine with yellow-emission fluorescence, which quenched the fluorescence intensity of red-emission carbon dots (RCDs) via inner-filter effect. Based on above mechanism, a ratiometric fluorescent system was established for OPs detection. Threaded 3D μPAD consisted of 4 layers, which allowed to load and/or add reagents to trigger the cascade reaction system for OPs detection. The fluorescent images presented distinguishable color variations from red to yellow with dichlorvos concentrations ranging from 2.5 to 120 μg L−1, and the limit of detection was 1.0 μg L−1. In the practical samples testing, threaded 3D μPAD can eliminate background influence on fluorescent signal for OPs detection. Threaded 3D μPAD integrated with ratiometric sensing platform has merits of accuracy response, facile operation, and background-free detection, which supplies a new alternative approach for on-site pesticide detection.

Advanced molecularly imprinted polymer-based paper analytical device for selective and sensitive detection of Bisphenol-A in water samples

Recently, the challenges in sensors have pointed towards rapid, on-site, and visual methods, especially when the sensing concerns toxic components such as Bisphenol-A (BPA). Herein, significant binding capacities for BPA have been featured the ultrasonically prepared molecularly imprinted polymer (MIP). Under the optimal adsorption conditions, which have been determined by a central composite design, the synthesized MIP exhibited a high imprinting factor of 9. The prepared MIP was effectively integrated into a membrane to fabricate an advanced paper-based analytical device (MIP-PAD) for the on-site colorimetric detection of BPA. The results of the evolved MIP-PAD were further analyzed by smartphone and processed by ImageJ software to quantify the BPA concentrations. The MIP-PAD platform exhibited a relevant performance for BPA sensitive sensing with a limit of detection and quantification of 0.03 μg/mL and 0.10 μg/mL, respectively. Moreover, trace levels of BPA (3.3 ng/mL) were successfully detected using MIP-PAD in SPE-tube with a loading volume of 1 mL. Besides, the fabricated chemical sensor revealed a high selectivity towards BPA after assessing various analogous compounds. Furthermore, this advanced technology was accurately and precisely applied for water samples and presented long-term stability.

Hollow-Channel Paper Analytical Devices Supported Biofuel Cell-Based Self-Powered Molecularly Imprinted Polymer Sensor for Pesticide Detection.

Herein, a paper-based glucose/air biofuel cell (BFC) was constructed and implemented for self-powered pesticide detection. Our developed paper-based chip relies on a hollow-channel to transport fluids rather than capillarity, which reduces analysis times as well as physical absorption. The gold nanoparticles (Au NPs) and carbon nanotubes (CNTs) were adapted to modify the paper fibers to fabricate the flexible conductive paper anode/cathode electrode (Au-PAE/CNT-PCE). Molecularly imprinted polymers (MIPs) using 2,4-dichlorophenoxyacetic acid (2,4-D) as a template were synthesized on Au-PAE for signal control. In the cathode, bilirubin oxidase (BOD) was used for the oxygen reduction reaction. Based on a competitive reaction between 2,4-D and glucose-oxidase-labeled 2,4-D (GOx-2,4-D), the amount of GOx immobilized on the bioanode can be simply tailored, thus a signal-off self-powered sensing platform was achieved for 2,4-D determination. Meanwhile, the coupling of the paper supercapacitor (PS) with the paper-based chip provides a simple route for signal amplification. Combined with a portable digital multi-meter detector, the amplified signal can be sensitively readout. Through rational design of the paper analytical device, the combination of BFC and PS provides a new prototype for constructing a low-cost, simple, portable, and sensitive self-powered biosensor lab-on-paper, which could be easily expanded in the field of clinical analysis and drug delivery.

A smartphone-assisted hybrid sensor for simultaneous potentiometric and distance-based detection of electrolytes

At home electrolyte analysis is of growing interest due to the importance for early diagnosis for various diseases. This work presents the first device that integrates a potentiometric ion-selective electrode (ISE) with distance-based colorimetric detection for the simultaneous analysis of K+ and Cl− ions at the point of care (POC). This hybrid sensing device was designed in a two-dimensional configuration using a plastic transparency sheet containing a stencil printed K+-ISE and a paper substrate for distance-based colorimetric detection of Cl−. K+ quantification was performed using a low-cost (<$25) lab-made Wi-Fi supported potentiometer with a custom smartphone application while Cl− ions were quantified with an instrument-free distance-based paper analytical device (dPAD). The total analysis time is 5 min once the sample is added. The K+-ISE showed a sensitivity of 55.89 ± 2.52 mV/decade from 0.1 to 100 mM with a limit of detection (LOD) of 0.01 mM. The linear working range for Cl− detection was 0.5–50 mM whereas the LOD was 0.16 ± 0.05 mM. The proof-of-concept application of the sensing hybrid device was demonstrated in human urine and artificial sweat samples containing K+ and Cl− ions at physiologically relevant ranges. The recoveries were found to be 88–108% for K+ and 90–104% for Cl−, showing the potential use of the proposed device for low-cost routine analysis of biological samples at POC.

Distance-Based All-In-One Immunodevice for Point-of-Care Monitoring of Cytokine Interleukin-6.

We report the development of a distance-based paper analytical device combined with a hydrophilic bridge valve (B-dPAD) as a quantitative immunoassay method to monitor human interleukin-6 (IL-6) in human samples. Our device design features (i) a circular sample inlet zone, (ii) a circular capture zone with immobilized anti-IL-6 (anti-Ab1), and (iii) a detection zone channel coated with methylene blue (MB). Two hydrophilic valves are positioned between these three zones. IL-6 levels were determined quantitatively by measuring the extent of degradation of MB to a colorless product along the length of the detection zone channel. Following method optimization, we obtained a linear range from 0.05 to 25.0 pg/mL (R2 = 0.9995) and a detection limit (LOD) of 0.05 pg/mL by the naked-eye readout. This is directly within the clinically relevant range. The system does not require any external instrumentation, and the bridge valves can be easily connected and disconnected by a minimally trained operator. The total analysis time is 35 min, significantly reduced from a typical ELISA assay, which takes around 1 h since the B-dPAD workflow circumvents washing steps. The device was tested for IL-6 quantification in human saliva and urine samples of volunteers, with no significant difference found between our method and the standard clinical laboratory method at 95% confidence levels. Recoveries ranged from 98 to 105% with the highest standard deviation at 3.9%. Our B-dPAD immunodevice is therefore a promising approach for rapid IL-6 monitoring in the context of point-of-care diagnostics and analysis in resource-limited settings.

A microfluidic paper analytical device using capture aptamers for the detection of PfLDH in blood matrices

BackgroundThe prevalence and death rate arising from malaria infection, and emergence of other diseases showing similar symptoms to malaria require the development of malaria-specific and sensitive devices for its diagnosis. To address this, the design and fabrication of low-cost, rapid, paper-based analytical devices (µPAD) using surface-immobilized aptamers to detect the presence of a recombinant malarial biomarker—Plasmodium falciparum lactate dehydrogenase (rPfLDH)—is reported in this study.MethodsTest zones on paper surfaces were created by covalently immobilizing streptavidin to the paper, subsequently attaching biotinylated aptamers to streptavidin. Aptamers selectively bound rPfLDH. The measurement of captured rPfLDH enzyme activity served as the means of detecting this biomarker. Enzyme activity across three replicate sensors was digitally quantified using the colorimetric Malstat assay.ResultsScreening of several different aptamers reported in the literature showed that aptamers rLDH7 and 2008s immobilized in this manner specifically recognised and captured PfLDH. Using rLDH7, the sensitivity of the µPAD sensor was evaluated and the µPAD sensor was applied for preferential detection of rPfLDH, both in buffered solutions of the protein and in spiked serum and red blood cell lysate samples. In buffered solutions, the test zone of the µPAD sensor exhibited a KD of 24 ± 11 nM and an empirical limit of detection of 17 nM, respectively, a limit similar to commercial antibody-based sensors exposed to rPfLDH. The specific recognition of 133 nM rPfLDH in undiluted serum and blood samples was demonstrated by the µPAD.ConclusionThe reported µPAD demonstrates the potential of integrating aptamers into paper-based malarial rapid diagnostic tests.Graphical The assembly of µPAD sensors using APTEC assay principles for the detection the malarial biomarker, lactate dehydrogenase enzymes from Plasmodium falciparum (PfLDH). The aptamers immobilized at the test zones capture the PfLDH in samples. After washing the unbound sample components from the zones, Malstat assay reagents are added for colour development, proportional to the amount of captured PfLDH.

Handmade Paper as a Paper Analytical Device for Determining the Quality of an Antidiabetic Drug.

Paper analytical devices (PADs) are a class of low-cost, portable, and easy-to-use platform for several analytical tests in clinical diagnostics, environmental pollution monitoring, and food and drug safety screening. These devices are primarily made from cellulosic paper. Considering the importance of eco-friendly and local or distributed manufacturing of devices realized during the COVID-19 pandemic, we systematically studied the potential of handmade Nepali paper to be used in fabricating PADs in this work. We characterized five different handmade papers made from locally available plant fibers using an eco-friendly method and used them to fabricate PADs for determining the drug quality. The thickness, grammage, and apparent density of the paper samples ranged from 198.6 to 314.8 μm, 49.1 to 117.8 g/m2, and 0.23 to 0.43 g/cm3, respectively. The moisture content, water filtration, and wicking speed ranged from 5.8 to 7.1%, 35.7 to 156.7, and 0.062 to 0.124 mms–1, respectively. Furthermore, the water contact angle and porosity ranged from 76.6 to 112.1° and 79 to 83%, respectively. The best paper sample (P5) was chosen to fabricate PADs for the determination of metformin, an antidiabetic drug. The metformin assay on PADs followed a linear range from 0.0625 to 0.5 mg/mL. The assay had a limit of detection and limit of quantitation of 0.05 and 0.18 mg/mL, respectively. The average amount of metformin concentration in samples collected from local pharmacies (n = 20) was 465.6 ± 15.1 mg/tablet. When compared with the spectrophotometric method, PAD assay correctly predicted the concentration of 90% samples. The PAD assay on handmade paper may provide a low-cost and easy-to-use system for screening the quality of drugs and other point-of-need applications.

A Novel Truncated DNAzyme Modified Paper Analytical Device for Point-of-Care Test of Copper Ions in Natural Waters

On-site determination of trace copper ions in natural waters is of great significance to environmental monitoring, and how to develop accurate and specific point-of-care test methods is one critical issue. In the study, a paper-based analytical device (PAD) being modified with a new truncated DNAzyme (CLICK-T, which was derived from a reported DNAzyme-CLICK-17) was developed for Cu ions detection. The detection mechanism was based on Cu(II)-catalyzed azide-alkyne cycloaddition (Cu(II)AAC) reaction. It can directly conduct on-site analysis of Cu(II) ions based on fluorescent signals detected using a mobile phone. In the assay, the CLICK-T was firstly modified on the PADs. Then, water samples containing Cu ions mixed with 3-azido-7-hydroxycoumarin and 3-butyn-1-ol were instantly dripped on PADs and incubated for 20 min. Finally, the PADs were excited at 365 nm and emitted fluorescence which could be analyzed on site using smart phones. The Cu(II) concentration could be quantified through RGB analysis with the aid of iPhone APP software. The limit of detection is 0.1 µM by the naked eye due to the fact that CLICK-T exhibited a good catalytic effect on Cu(II)AAC. The Cu(II) concentration could also be directly detected without using reductant, such as ascorbic acid, which is prone to be oxidized in air. This simplifies the PDA detection process improves its efficiency. The PAD is convenient for the on-site analysis of Cu ions in natural waters.

The detection of Mercury(II) ions using fluorescent gold nanoclusters on a portable paper-based device

To minimize the need for complex testing procedures, sophisticated instrumentation, and electricity for on-site testing, we demonstrate a simple and portable gold nanocluster (AuNC)-modified paper analytical device integrated with syringe-driven fluid flow to enable highly sensitive mercury ion (Hg2+) detection for environmental monitoring. The device is composed of a paper substrate modified with fluorescent AuNCs (AuNC-paper), which is held within a reusable cartridge connected to a syringe, thus allowing users to flow a large volume of the sample solution through the paper test for greater accumulation of the analyte signal. The metallophilic d10-d10 interaction of Hg2+ with Au+ on the surface of the AuNC-paper induces fluorescence quenching, which can be monitored using a smartphone. Importantly, the red-emitting AuNCs avoid interference with the background fluorescence of the paper substrate. Additionally, the AuNCs are strongly-attached to the paper substrate via carbodiimide coupling, which helps prevent the AuNCs from leaching and enables a large amount of solution to interact with the test (up to 2.5 mL) to increase the amount of the target ions that react with the AuNC-paper. As a result, without the need for preconcentrating the test solution, this paper device can provide the highly sensitive detection of Hg2+ ions, including a 26-fold higher sensitivity than the AuNC-modified test paper without a fluidic cartridge, at a low level of down to nM. The paper platform can complete the detection of Hg2+ ions within 30 min, with a detection limit as low as 1.2 nM, which is less than the United States Environmental Protection Agency’s regulatory limit for drinking water. This highly sensitive, selective, portable, and easy-to-operate platform may be valuable for on-site mercury pollution monitoring in resource-constrained settings.

A paper-analytical device for detecting bisphenol-A in foods.

Bisphenol A (BPA) is a plastic monomer that can leach into food and cause adverse health effects with long-term exposure. In this study, we developed simple paper-analytical devices (PADs) for detecting BPA in food. The PADs were designed with hydrophilic and hydrophobic areas via wax printing. The hydrophilic areas were designed as a detection zone and modified with carboxymethyl cellulose (CMC) for the immobilisation of BPA-bovine serum albumin (BSA). The monoclonal antibodies against BPA were generated and modified with quantum dots (QDs) to synthesise QD-antibody (QD-Ab) probes. Detection conditions of the assay were optimized, with results of 0.1 μg of BPA-BSA and 30-fold diluted QD-Ab probes. The detection limit was 0.098 μg L-1 using ImageJ analysis. Samples of drinking water, green tea beverage and peanut cooking oil were selected to conduct the matrix effect study. The recovery rates of BPA in different samples ranged from 78.77% to 118.96%, proving that the PADs were a simple and sensitive detection method for easy, low-cost analysis of real food samples.

Advanced Molecularly Imprinted Polymer-Based Paper Analytical Device for Selective and Sensitive Detection of Bisphenol-A in Water Samples

Advanced Molecularly Imprinted Polymer-Based Paper Analytical Device for Selective and Sensitive Detection of Bisphenol-A in Water Samples

Enhanced Catalytic Activity Induced by the Nanostructuring Effect in Pd Decoration onto Doped Ceria Enabling an Origami Paper Analytical Device for High Performance of Amyloid-β Bioassay.

In this work, we fabricated a novel origami paper-based analytical device (oPAD) assisted by the nanostructuring effect of in situ Pd decoration of Cu/Co-doped CeO2 (CuCo-CeO2-Pd) nanospheres, functionalized with their strongly enhanced electrocatalytic properties to realize an electrochemical and visual signal readout system in oPAD, for highly sensitive detection of amyloid-β (Aβ). The CuCo-CeO2-Pd nanospheres were introduced as an enhanced "signal transducer layer" on account of the electron transfer acceleration caused by catalyzing glucose to produce H2O2 for differential pulse voltammetry signal readout and further 3,3'5,5'-tetramethylbenzidine (TMB) oxidation for colorimetric analysis. Meanwhile, for achieving superior performance of the proposed oPAD, in situ growth of urchin-like gold nanoparticles (Au NPs) onto cellulose fibers was adopted to improve "the recognition layer" in favor of immobilizing antibodies for targeting Aβ through specific antigen-antibody interactions. Combined with the delicate design of oPAD, exhibiting actuation of the conversion procedure between hydrophobicity and hydrophilicity on paper tabs in the assay process, the oPAD successfully enabled sensitive diagnosis of Aβ in a linear range from 1.0 pM to 100 nM with a limit of detection of 0.05 pM (S/N = 3) for electrochemical detection, providing a reliable strategy for quantifying the Aβ protein in clinical applications.

Paper based analytical devices for blood grouping: a comprehensive review.

The clinical importance of blood group (BG) antigens is related to their ability to induce immune antibodies that can cause hemolysis. Yet, ABO and D (Rh) are still considered to be the key antigens for healthy blood transfusion and secondary antigens are the next priority. Serological typing is the most widely used typing method. Rapid and accurate blood grouping plays an important role in some clinical conditions, rather than conventional techniques. Hence, developing a simple and economical model for rapid blood grouping would facilitate these tests. In recent decades, paper-based microfluidics such as μPADs has gained much interest in wide application areas such as point-of-care diagnostic. In this study, we evaluated μPADs that are performed for blood grouping and its recent progress.A comprehensive literature search was performed using databases including PUBMED, SCOPUS, Web of Science and Google Scholar. Keywords were blood grouping or typing, paper analytical device, rapid test, etc.After investigation of search results, 16 papers from 2010 to 2020 were included. Further information in detail was classified in Table 1. Generally, two principles for blood typing μPADs are introduced. The lateral chromatographic flow method and the vertical flow-through method that detects BG in a visual-based manner. To detect results with acceptable clarity many factors and challenges like paper, blood sample, buffer, Ab and RBC interaction and also μPADs stability need to be considered, which are discussed. In conclusion, the simplicity, stability, cheapness, portability and biocompatibility of μPADs for blood grouping confirming its utility and also they have the capability to robust, universal blood-grouping platform. Table 1 Summary of blood grouping tests using paper-based analytical devices Antigens Type of diagnosis Validation method Sample No Accuracy Action time Paper type Stability Sample dilution Buffer Ref A, B, Rh Forward volunteers records 5 - - Whatman No. 4 - 1/2 PBS* (Khan et al. 2010) A, B, Rh Forward gel assay test and conventional slide test 100 100% 1min Whatman No. 4 and Kleeenex paper towel 7 Days in 4°C 1/1 NSS (Al-Tamimi et al. 2012) A, B, Rh Forward gel card assay 99 100% 20 Sec + Washing Kleeenex paper towel - 1/1 NSS (Li et al. 2012) A, B, Rh Forward - - - - Kleeenex paper towel - 45/100 PSS (Li et al. 2013) A, B, Rh Forward gel card assay 98 100% 1.5min Kleeenex paper towel - 85/100 PBS (Guan et al. 2014b) C, E, c, e, K, Jka, Jkb, M, N, S, P1, and Lea Forward gel card assay 266 100% - Kleeenex paper towel - 1/1 NSS (Li et al. 2014b) A, B, Rh Forward and Reverse conventional slide test 96 ≈ 91% 10min Whatman No. 1 21 Days in 4°C 1/2 NSS (Noiphung et al. 2015) C, c, E, e, K, k, Fya, Fyb, Jka, Jkb, M, N, S and s, P1, Lea and Leb Forward - 478 - - Kleeenex paper towel - 1/1 NSS, PBS (Then et al. 2015) A, B Forward and Reverse conventional slide test 76 100% 5-8min Whatman No. 4 38 Days in 4°C 1/4, 1/1 NSS (Songjaroen and Laiwattanapaisal 2016) D, K Forward volunteers records 210 - 7.5min Kleenex paper towel - 1/1 NSS (Yeow et al. 2016) A, B, c, e, D, C, E, M, N, S, s, P1, Jka, Jkb, Lea, Leb, Fya, and Fyb Forward and Reverse gel card assay 3550 ≈100% 30s Fiber glass and cotton linter 180 Days in 25°C 45/100, 1/1 PBS (Zhang et al. 2017) A, B Forward conventional slide test 598 100% 3min Whatman No. 113 14 Day in 4°C 1/1 NSS (Songjaroen et al. 2018) A, B, Rh Forward conventional slide test - - 30 Sec + Washing Unrefined sisal paper - 1/2 NSS (Casals-Terré et al. 2019) A, B, Rh Forward - - - - Whatman No.1 - 1/1 NSS (Ansari et al. 2020) ABO & Rh Forward and Reverse conventional slide test - 100% Unrefined Eucalyptus papers - 1/2 NSS, PBS (Casals-Terré et al. 2020) A, B, Rh Forward - - - 30 Sec + Washing Whatman No. 4 modified with chitosan ≥ 100days in 25°C 1/1 NSS (Parween et al. 2020) *phosphate buffer saline, normal saline solution.

Development of Field Deployable Sensor for Detection of Pesticide From Food Chain

The use of pesticides in agriculture field remains a serious issue related to public health. This necessitates the need to develop a low cost/portable, sensitive and selective bio-sensing platform for detection of pesticides in food chain. In this work a low-cost biosensing platform for ultrasensitive detection of chlorpyrifos (CPF) is developed. Electrochemical micro Paper Analytical Device ( $\text{E}\mu $ PAD) is fabricated by conventional screen-printing technology. Metal Organic Framework (Z1200 MOF) having zinc metal and imidazole ligand is used as a transducing element which facilitates biocompatible matrix for Acetylcholinesterase (AChE) enzyme immobilization. The limit of detection for CPF is found be 3 ng/L with sensitivity 0.521 $\text{k}\Omega $ /ng $\text{L}^{-1}$ /mm $^{2}$ . The sensor required $100\mu \text{L}$ of reagent and was tested with a linear concentration range of 10 ng/L to 1000 ng/L with response time of 5s. The sensor is further integrated with portable electronics based on Arduino microcontroller and Artificial Intelligence (AI) which provided economical, portable and user-friendly sensing platform. The stability of the sensor was 30 days. The developed sensor was also tested with real samples and the sensor response is in agreement with conventional technique.

Aggregation-induced emission luminogen@manganese dioxide core-shell nanomaterial-based paper analytical device for equipment-free and visual detection of organophosphorus pesticide

Organophosphorus pesticide (OP) residues have gathered considerable attention because of their significant threat to society development and healthy life. Developing a sensitive and practical OPs sensor is highly urgent, whereas remains a huge challenge. To this end, we fabricated a high-performance fluorescence paper analytical device (PAD) for apparatus-free and visual sensing of OPs based on aggregation-induced emission (AIE) luminogen’s bright emission in aggregated state, unique response of MnO2 to thiol compounds, and difference of MnO2 and Mn2+ in quenching fluorescence. AIE nanoparticles PTDNPs-0.10 and MnO2 respectively acted as core and shell to prepare PTDNPs@MnO2, which possessed high stability and were dripped on cellulose paper’s surface to fabricate AIE-PAD. The sensing mechanism is that OPs-treated acetylcholinesterase (AChE) prevents the formation of thiocholine, thereby minimizing the reduction of MnO2 into Mn2+ and changing the output signal. As a result, equipment-free and visual sensing of OPs was acquired with limit of detection of 1.60 ng/mL. This work justifies the feasibility of applying core-shell material to develop high-performance sensor and substituting complex/expensive solution-phase sensor with PAD, providing a new avenue to bring OPs analysis out of the lab and into the world.

A manual and portable centrifuge combined with a paper-based immunoassay for myocardial infarction diagnosis

Myocardial infarction (MI) causes hundreds of thousands of deaths annually. Early diagnosis of MI by detecting the concentration of troponin I in plasma can help limit mortality rates. However, plasma separation and early diagnosis are particularly difficult to achieve in resource-limited settings. In this study, we demonstrate a manual and portable centrifuge along with a paper analytical device to measure troponin I for early MI diagnosis. With this so-called “Handfuge,” pure plasma can be achieved with a yield of up to 47.1% and purity as high as 99.9% in less than 3 min without electricity. The resulting plasma can then be directly used for detecting troponin I using a paper-based enzyme-linked immunosorbent assay (ELISA), with a detection limit as low as 0.03 ng/mL. The whole detection process consumes just 10 µL of blood, which is similar to the volume obtained by a clinical finger-prick. The proposed centrifuge together with the paper analytical device possesses the potential to replace existing techniques in troponin I detection for early MI diagnoses in resource-limited regions of the world.