Point-of-care coagulation monitoring: first clinical experience using a paper-based lateral flow diagnostic device

A smartphone-integrated deep learning strategy-assisted rapid detection system for monitoring dual-modal immunochromatographic assay

This study focuses on the integration of a custom-built and optimally trained YOLO v5 model into a smartphone app developed with Java language. A dual-modal immunochromatographic rapid detection system based on a deep learning strategy for smartphones was developed for grade determination and predicting the concentration of aflatoxin B1 (AFB1). Innovative distance-type quantum dot microsphere fluorescent immunochromatographic chips enable semi-quantitative analysis by naked eye, and conventional colloidal gold nanoparticle colorimetric strips were also prepared. The compact and versatile hardware device making it easily integrable into smartphones of varying dimensions. Moreover, the wireless charging functionality of smartphones was to tackle power supply challenges. After optimized training, the accuracy, mAP@0.5, precision, and recall metrics of the YOLO v5 model all soared to 98 %. For the dual-modal immunochromatographic chips, the R2 values for the standard curve fits were as high as 0.993, with a broad linear range of 0.05-40 ng/mL and a standard deviation lower than 0.03 at each concentration. Finally, this system determined the grade of the AFB1 concentration with an accuracy of up to 98 % and it exhibited an ultra-sensitive quantitative detection capability with a limit of detection as low as 2.2 pg/mL, showcasing the reliability of the deep learning strategy for practical applications in smartphones. This robust technological foundation paves the way for potentially community-based, family-oriented, and personalized applications.

Unveiling the state of the art: a systematic review and meta-analysis of paper-based microfluidic devices

Introduction

This systematic review and meta-analysis present a comprehensive evaluation of paper-based microfluidic devices, focusing on their applications in immunoassays. These devices are emerging as innovative solutions to democratize access to diagnostic technologies, especially in resource-limited settings. Our review consolidates findings from diverse studies to outline advancements in paper-based microfluidic technology, including design intricacies and operational efficacy. Key advantages such as low cost, portability, and ease of use are highlighted.

Materials and Methods

The review categorizes literature based on the design and operational nuances of these diagnostic tools, exploring various methodologies, fabrication techniques, detection methods, and applications, particularly in protein science. The meta-analysis extends to the diverse applications of these technologies, providing a framework for classifying and stratifying their uses in diagnostics.

Results and discussion

Notable findings include a critical analysis of performance metrics, such as sensitivity and specificity. The review addresses challenges, including the need for further validation and optimization for broader clinical applications. A critical discussion on the validation processes, including cross-validation and rigorous control testing, is provided to ensure the robustness of microfluidic devices. This study offers novel insights into the computational strategies underpinning these technologies and serves as a comprehensive roadmap for future research, potentially broadening the impact across the protein science universe.

Development of Novel Paper-Based Assay for Direct Serum Separation

Background: Many conventional laboratory tests require serum separation using a clot activator/gel tube, followed by centrifugation in an equipped laboratory. The aim of this study is development of novel, equipment-free, paper-based assay for direct and efficient serum separation. Methods: Fresh blood was directly applied to wax-channeled filter paper treated with clotting activator/s and then observed for serum separation. The purity, efficiency, recovery, reproducibility, and applicability of the assay were validated after optimization. Results: Serum was successfully separated using activated partial thromboplastin time (APTT) reagent and calcium chloride-treated wax-channeled filter paper within 2 min. The assay was optimized using different coagulation activators, paper types, blood collection methods, and incubation conditions. Confirmation of serum separation from cellular components was achieved by direct visualization of the yellow serum band, microscopic imaging of the pure serum band, and absence of blood cells in recovered serum samples. Successful clotting was evaluated by the absence of clotting of recovered serum by prolonged prothrombin time and APTT, absence of fibrin degradation products, and absence of Staphylococcus aureus-induced coagulation. Absence of hemolysis was confirmed by undetectable hemoglobin from recovered serum bands. The applicability of serum separated in paper was tested directly by positive color change on paper using bicinchoninic acid protein reagent, on recovered serum samples treated with Biuret and Bradford reagents in tubes, or measurement of thyroid-stimulating hormone and urea compared to standard serum samples. Serum was separated using the paper-based assay from 40 voluntary donors and from the same donor for 15 days to confirm reproducibility. Dryness of coagulants in paper prevents serum separation that can be re-stored by a re-wetting step. Conclusions: Paper-based serum separation allows for development of sample-to-answer paper-based point-of-care tests or simple and direct blood sampling for routine diagnostic tests.

Microfluidic techniques for mechanical measurements of biological samples

The use of microfluidics to make mechanical property measurements is increasingly common. Fabrication of microfluidic devices has enabled various types of flow control and sensor integration at micrometer length scales to interrogate biological materials. For rheological measurements of biofluids, the small length scales are well suited to reach high rates, and measurements can be made on droplet-sized samples. The control of flow fields, constrictions, and external fields can be used in microfluidics to make mechanical measurements of individual bioparticle properties, often at high sampling rates for high-throughput measurements. Microfluidics also enables the measurement of bio-surfaces, such as the elasticity and permeability properties of layers of cells cultured in microfluidic devices. Recent progress on these topics is reviewed, and future directions are discussed.

Development of a paper-based lateral flow prothrombin assay

Disorders of haemostasis result in both excessive bleeding and clotting and are a major global cause of morbidity and mortality, particularly in the developing world. A small number of simple tests can be used to screen and monitor for such dysfunctions, one of which is the prothrombin time (PT) test and associated International Normalisation Ratio (INR). PT/INR is routine in hospital laboratories in developed countries, and can also be performed using point-of-care instruments. However, neither of these approaches is appropriate in low-resource settings. Significant interest has grown in paper-based devices to form the basis of simple and low-cost assays that may have the potential for application in such environments. This study describes the development of a simple, low-cost, paper-based lateral flow prothrombin assay. The assay employed wax printing on chromatography paper to define test channels, with deposition of thromboplastin reagent and calcium chloride onto the resulting strips. These were placed in a test housing and measurement of the flow rates of deposited plasma samples were performed in triplicate. The flow dynamics of the assay was optimised according to the type of paper substrate used, the nature and quantity of the thromboplastin reagent, the amount of calcium chloride required, and the volume of sample employed. An optimised assay configuration demonstrated a dynamic range of 6 mm between normal and factor-deficient plasmas. The assay showed good correlation with laboratory-based PT assay (Yumizen G200) in artificial plasmas in the 9.8 to 36 s range (r² = 0.8112). The assay also demonstrated good dynamic range and correlation in patient plasma samples in comparison with hospital PT, with a range of 9.8 to 45 s (r² = 0.7209).

Paper-based analytical devices for point-of-care blood tests

Blood can be a window to health, and as a result, is the most intensively studied human biofluid. Blood tests can diagnose diseases, monitor therapeutic drugs, and provide information about the health of an individual. Rapid response blood tests are becoming increasingly essential, especially when subsequent treatment is required. Toward this need, paper-based devices have been excellent tools for performing blood tests due to their ability to conduct rapid and low-cost diagnostics and analyses in a non-laboratory environment. In this Perspective, we review recent advances in paper-based blood tests, particularly focusing on the specific techniques and assays applied. Additionally, we discuss the future of these paper-based devices, such as how the signal intensity can be enhanced and how the in situ synthesis of nanomaterials can be used to improve the sensitivity, functionality, and operational simplicity. With these advances, paper-based devices are becoming increasingly valuable tools for point-of-care blood tests in various practical scenarios.

Evolving Paradigm of Prothrombin Time Diagnostics with Its Growing Clinical Relevance towards Cardio-Compromised and COVID-19 Affected Population

Prothrombin time (PT) is a significant coagulation (hemostasis) biomarker used to diagnose several thromboembolic and hemorrhagic complications based on its direct correlation with the physiological blood clotting time. Among the entire set of PT dependents, candidates with cardiovascular ailments are the major set of the population requiring lifelong anticoagulation therapy and supervised PT administration. Additionally, the increasing incidence of COVID affected by complications in coagulation dynamics has been strikingly evident. Prolonged PT along with sepsis-induced coagulopathy (SIC score > 3) has been found to be very common in critical COVID or CAC-affected cases. Considering the growing significance of an efficient point-of-care PT assaying platform to counter the increasing fatalities associated with cardio-compromised and coagulation aberrations propping up from CAC cases, the following review discusses the evolution of lab-based PT to point of care (PoC) PT assays. Recent advances in the field of PoC PT devices utilizing optics, acoustics, and mechanical and electrochemical methods in microsensors to detect blood coagulation are further elaborated. Thus, the following review holistically aims to motivate the future PT assay designers/researchers by detailing the relevance of PT and associated protocols for cardio compromised and COVID affected along with the intricacies of previously engineered PoC PT diagnostics.

Technical considerations to development of serological tests for SARS-CoV-2

The COVID-19 pandemic has had a devastating impact worldwide and has brought clinical assays both for acute diagnosis and prior exposure determination to the forefront. Serological testing intended for point-of-care or laboratory use can be used to determine more accurate individual and population assessments of prior exposure to SARS-CoV-2; improve our understanding of the degree to which immunity is conveyed to subsequent exposures; and quantify immune response to future vaccines. In response to this pandemic, initially more than 90 companies deployed serology assays to the U.S. market, many of which made overstated claims for their accuracy, regulatory approval status, and utility for intended purpose. The U.S. Food and Drug Administration subsequently instituted an Emergency Use Authorization (EUA) procedure requiring that manufacturers submit validation data, but allowing newly developed serological tests to be marketed without the usual approval process during this crisis. Although this rapid deployment was intended to benefit public health, the incomplete understanding of immune response to the virus and lack of assay vetting resulted in quality issues with some of these tests, and thus many were withdrawn after submission. Common assay platforms include lateral flow assays which can serve an important niche of low cost, rapid turnaround, and increased accessibility whereas established laboratory-based platforms based on ELISAs and chemiluminescence expand existing technologies to SARS-CoV-2 and can provide throughput and quantification capabilities. While most of the currently EUA assays rely on these well-established platforms, despite their apparent technical simplicity, there are numerous practical challenges both for manufacturers in developing and for end-users in running and interpreting such assays. Within are discussed technical challenges to serology development for SARS-CoV-2, with an emphasis on lateral flow assay technology.

Fully integrated rapid microfluidic device translated from conventional 96-well ELISA kit

In this work, a fully integrated active microfluidic device transforming a conventional 96-well kit into point-of-care testing (POCT) device was implemented to improve the performance of traditional enzyme-linked immunosorbent assay (ELISA). ELISA test by the conventional method often requires the collection of 96 samples for its operation as well as longer incubation time from hours to overnight, whereas our proposed device conducts ELISA immediately individualizing a 96-well for individual patients. To do that, a programmable and disposable on-chip pump and valve were integrated on the device for precise control and actuation of microfluidic reagents, which regulated a reaction time and reagent volume to support the optimized protocols of ELISA. Due to the on-chip pump and valve, ELISA could be executed with reduced consumption of reagents and shortening the assay time, which are crucial for conventional ELISA using 96-well microplate. To demonstrate highly sensitive detection and easy-to-use operation, this unconventional device was successfully applied for the quantification of cardiac troponin I (cTnI) of 4.88 pg/mL using a minimum sample volume of 30 µL with a shorter assay time of 15 min for each ELISA step. The limit of detection (LOD) thus obtained was significantly improved than the conventional 96-well platform.

Quantitative hematocrit measurement of whole blood in a point-of-care lateral flow device using a smartphone flow tracking app

We present a rapid and quantitative point-of-care (PoC) system based on a smartphone application that is capable of accurately tracking the flow of red blood cells (RBCs) through a no-reaction lateral flow assay (nrLFA) device. Utilizing only the camera feed from the smartphone and built-in image processing, the nrLFA is identified and RBC fluid flow distances and rates are recorded in parallel with the test without the need of any custom hardware or enclosure. We demonstrated the application by first measuring and then calculating hematocrit (Hct) values of whole blood samples with nominal content of 28%, 35%, 40%, and 45% Hct on the nrLFA platform. The PoC system was able to accurately measure (to within 1% Hct of nominal values) whole blood Hct in ~10-20 s after sample dispensing.

Microfluidics in Haemostasis: A Review

Haemostatic disorders are both complex and costly in relation to both their treatment and subsequent management. As leading causes of mortality worldwide, there is an ever-increasing drive to improve the diagnosis and prevention of haemostatic disorders. The field of microfluidic and Lab on a Chip (LOC) technologies is rapidly advancing and the important role of miniaturised diagnostics is becoming more evident in the healthcare system, with particular importance in near patient testing (NPT) and point of care (POC) settings. Microfluidic technologies present innovative solutions to diagnostic and clinical challenges which have the knock-on effect of improving health care and quality of life. In this review, both advanced microfluidic devices (R&D) and commercially available devices for the diagnosis and monitoring of haemostasis-related disorders and antithrombotic therapies, respectively, are discussed. Innovative design specifications, fabrication techniques, and modes of detection in addition to the materials used in developing micro-channels are reviewed in the context of application to the field of haemostasis.

Point-of-Care Assessment of Hemostasis with a Love-Mode Surface Acoustic Wave Sensor

Monitoring of the hemostasis status is essential for therapeutic anticoagulants, undergoing surgery, cardiovascular diseases, etc. Although the clinical values of conventional blood coagulation tests have been well demonstrated, these devices have limitations such as large and expensive equipment, excessive sample volumes, long turnaround times, and difficulty in miniaturization for point-of-care use. Here, we present a novel strategy to evaluate blood hemostasis using the single-port Love-mode surface acoustic wave (SLSAW) sensor. The SLSAW sensor was designed as a plug-and-play-type unit for disposable use and operated under the harmonic resonant mode to produce frequency response to the blood coagulation cascade. Compared with a quartz crystal microbalance, Lamb wave, and film bulk acoustic resonator, the frequency shift of SLSAW was significantly increased, ranging from approximately 8960 to 10 368 kHz, which indicated enhancement of the signal-to-noise ratio. To demonstrate the feasibility of the SLSAW, studies were carried out to examine the effects of temperature and clotting reagents on coagulation times and kinetics. Activated partial thromboplastin times of plasma were validated by comparing with SYSMEX CA-7000 with the correlation (R²) as 0.996. In terms of coagulation kinetics, reaction time, clot formation time, maximum frequency shift, and clot formation rate of whole blood correlated well with corresponding parameters of the standard thromboelastography (TEG) analyzer (R² = 0.9942, 0.9868, 0.9712, and 0.9939, respectively). The SLSAW sensor, with the advantages of low cost, small size, little sample consumption (1 μL), disposable use, and simple operation, is a promising tool for point-of-care diagnosis of hemostasis.

Technology Advancements in Blood Coagulation Measurements for Point-of-Care Diagnostic Testing

In recent years, blood coagulation monitoring has become crucial to diagnosing causes of hemorrhages, developing anticoagulant drugs, assessing bleeding risk in extensive surgery procedures and dialysis, and investigating the efficacy of hemostatic therapies. In this regard, advanced technologies such as microfluidics, fluorescent microscopy, electrochemical sensing, photoacoustic detection, and micro/nano electromechanical systems (MEMS/NEMS) have been employed to develop highly accurate, robust, and cost-effective point of care (POC) devices. These devices measure electrochemical, optical, and mechanical parameters of clotting blood. Which can be correlated to light transmission/scattering, electrical impedance, and viscoelastic properties. In this regard, this paper discusses the working principles of blood coagulation monitoring, physical and sensing parameters in different technologies. In addition, we discussed the recent progress in developing nanomaterials for blood coagulation detection and treatments which opens up new area of controlling and monitoring of coagulation at the same time in the future. Moreover, commercial products, future trends/challenges in blood coagulation monitoring including novel anticoagulant therapies, multiplexed sensing platforms, and the application of artificial intelligence in diagnosis and monitoring have been included.

A paper-based length of stain analytical device for naked eye (readout-free) detection of cystic fibrosis

The test of sweat chloride is routinely performed as a worldwide newborn screening (NBS) to the diagnosis of cystic fibrosis (CF) in infants. However, the available methods for measurement of chloride in sweat suffer from such limitations as either low selectivity and/or requiring relatively large sample size. In this work, we have designed an analytical ruler that can measure chloride ion in sweat and hence can be used for the diagnosis of cystic fibrosis. This micro-pad (μ-PAD) device is fabricated by making hydrophilic micro-channel on a filter paper impregnated with silver dichromate. After addition of chloride ion-containing sweat sample, it moves through the channel, leading to the formation of an AgCl sediment, which deposits as a white color stain, the length of which in the channel being proportional to the amount of chloride ion in sweat. A well-defined linear relation was observed between the length of white color stain and the concentration of chloride ion in the sample solutions with a relative standard deviation of 3.6% (n = 3) for an artificial sweat sample containing 100 mM chloride ion. The possible interfering effects of several different cations and anions on the detection of chloride ion were investigated and the results well-confirmed the selectivity of the proposed method. With the use of only 2.0 μL of the sample solution, the μPAD was able to measure the chloride content of sweat over a concentration range of 20.0-100.0 mM, which covers both the healthy range (˂ 40 mM) and the risky range (˃60 mM) of chloride ion. Analysis of chloride content of sweat samples by the μPAD agreed well with those obtained by a standard electrochemical method (with relative errors of lower than 10%).

Rapid paper diagnostic for plasma fibrinogen concentration

Fibrinogen is one of the first proteins to be depleted in heavily bleeding patients. In this study, we have developed a new paper-based diagnostic to quantify the fibrinogen concentration in blood at room temperature.

Microfluidic and Paper-Based Devices for Disease Detection and Diagnostic Research

Recent developments in microfluidic devices, nanoparticle chemistry, fluorescent microscopy, and biochemical techniques such as genetic identification and antibody capture have provided easier and more sensitive platforms for detecting and diagnosing diseases as well as providing new fundamental insight into disease progression. These advancements have led to the development of new technology and assays capable of easy and early detection of pathogenicity as well as the enhancement of the drug discovery and development pipeline. While some studies have focused on treatment, many of these technologies have found initial success in laboratories as a precursor for clinical applications. This review highlights the current and future progress of microfluidic techniques geared toward the timely and inexpensive diagnosis of disease including technologies aimed at high-throughput single cell analysis for drug development. It also summarizes novel microfluidic approaches to characterize fundamental cellular behavior and heterogeneity.

Engineering a simple lateral flow device for animal blood coagulation monitoring

Increasing numbers of animals are diagnosed with thromboembolism, requiring anticoagulation treatment to prevent thrombotic events. Frequent and periodic coagulation monitoring is critical to ensure treatment effectiveness and patient safety by limiting blood coagulation ability within the desired therapeutic range. Point-of-care diagnostics is an ideal candidate for frequent coagulation monitoring due to rapid test results and no need for laboratory setting. This article reports the first utilization of no-reaction lateral flow assay (nrLFA) device for simple and low-cost animal blood coagulation monitoring in resource-limited setting. The nrLFA device consists of sample pad, analytical membrane and wicking pad, without conjugate pad, reagent printing or membrane drying. Citrated and heparinized animal blood were utilized to mimic different blood coagulation abilities in vitro by adding reversal agents CaCl2 and protamine sulfate. The travel distance of red blood cells (RBCs) on the nrLFA after a pre-determined test time serves as endpoint marker. Upon adding 500 mM CaCl2 solution to citrated bovine, canine, rabbit and equine blood, the average travel distance decreases from 10.9 to 9.4 mm, 8.8 to 5.7 mm, 12.6 to 9 mm, and 15.3 to 11.3 mm, respectively. For heparinized bovine and rabbit blood, the average distance decreases from 14.5 to 11.4 mm and from 9.8 to 7.2 mm, respectively, when adding 300 mg/l protamine sulfate solution. The effect of hematocrit on RBC travel distance in the nrLFA was also investigated. The nrLFA device will potentially improve treatment efficiency, patient safety, quality of life, and satisfaction for both animal patients and their owners.