Point Of Care Diagnostics Research Articles

Nanomaterials integrated with microfluidic paper-based analytical devices for enzyme-free glucose quantification

In this study, nanomaterials capable of enzyme-free glucose quantification and colorimetric readout are integrated into a microfluidic paper-based analytical devices (μPADs). Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) were utilized as a peroxidase-like nanozyme and a colorimetric probe to achieve glucose monitoring. In this developed device, glucose is oxidized by AuNPs to generate hydrogen peroxide (H2O2), which flows in the paper microchannels toward detection zones. H2O2 then etches the immobilized AgNPs to induce a color change. The intensity of color change is easily monitored using a smartphone application. Following method optimization, we obtained a linear range from 0.50 to 10.0 mmol L−1 (R2 = 0.9921) and a detection limit (LOD) of 340.0 μmol L−1. This falls in the clinically relevant range for glucose monitoring and diabetes diagnosis in humans. In addition, the total analysis time is just 20 min, which is significantly less than the same experiment performed in the solution phase. Also, our method is markedly selective; other substrates do not interfere. The recovery test in human control samples was in the range of 98.47–102.34% and the highest relative standard deviation (RSD) was 3.58%. The enzyme-free approach for glucose sensing is highly desirable for diabetes diagnosis as it replaces the more expensive enzyme with cheaper nanomaterials. Furthermore, since nanomaterials are more environmentally stable compared to enzymes, it has the potential for widespread deployment as point-of-care diagnostics (POC) in resource-limited settings.

Predisposition to soil-transmitted helminth reinfection after four rounds of mass drug administration: results from a longitudinal cohort in the Geshiyaro project, a transmission elimination feasibility study in the Wolaita zone of southern Ethiopia.

Current WHO strategies for reaching soil-transmitted helminths (STH) elimination as a public health problem excludes treating certain adult populations in endemic areas, creating infection reservoirs that drive 'bounce back' of STH infection to pretreatment levels post-mass drug administration (MDA). Predisposition is a widespread, but poorly understood phenomena among helminth infections where individuals are predisposed to reinfection after repeated treatments. This analysis uses Geshiyaro project data, an STH control programme exploring transmission interruption by community-wide MDA and enhanced water, sanitation and hygiene during 2019-2023. Parasitological survey data from longitudinal cohorts are analysed using Kendall's Tau-b rank correlation to assess the evidence for predisposition to light or heavy infection between four consecutive rounds of MDA. Correlation analyses revealed the strongest evidence for predisposition to heavy or light Ascaris lumbricoides infection was between survey 1 and 2 (Tau-b 0.29; p<0.001). Overall patterns were not observed for Trichuris trichiura or hookworm infections, however, some significant and notable correlations were recorded for some stratifications and time points. Evidence for predisposition in endemic settings in southern Ethiopia with low STH prevalence suggests that more targeted approaches to MDA in those predisposed to infection may be a sensible control strategy if cheap, point of care diagnostics are available.

Trauma team activation-Who should be alerted for which patients?

It is estimated that in total almost 10million people are injured in accidents in Germany every year, most of which are in the household milieu and leisure sector. It is estimated that of these more than 32,000 seriously injured patients are admitted to the emergency room every year. It is recommended that the decision of the prehospital treatment team or the first examiner in the hospital as to whether apotentially severely injured patient should be admitted via the emergency room of the hospital should be based on acatalogue of criteria. Against the background of the update of the S3guidelines on the treatment of multiple trauma/severely injured patients and on the basis of the current literature, an overview with respect to the composition of the team and the criteria for which an emergency room team is or should be activated is given. Alerting the emergency room team is still recommended if acertain injury pattern is present or if a prehospital intervention is necessary. The B‑criteria based on the course of the accident or mechanism, which have recently been the subject of increasing criticism, have been adapted. Recommendations for geriatric patients could also be formulated. Compared to the S3guidelines from 2016 the emergency room alarm criteria could be revised on the basis of new literature and have been included in the revised guidelines. There is no doubt that further optimization. e.g., based on prehospital algorithms or using point of care diagnostics, are possible and desirable in the future.

Magnetite-Based Biosensors and Molecular Logic Gates: From Magnetite Synthesis to Application

In the last few decades, point-of-care (POC) sensors have become increasingly important in the detection of various targets for the early diagnostics and treatment of diseases. Diverse nanomaterials are used as building blocks for the development of smart biosensors and magnetite nanoparticles (MNPs) are among them. The intrinsic properties of MNPs, such as their large surface area, chemical stability, ease of functionalization, high saturation magnetization, and more, mean they have great potential for use in biosensors. Moreover, the unique characteristics of MNPs, such as their response to external magnetic fields, allow them to be easily manipulated (concentrated and redispersed) in fluidic media. As they are functionalized with biomolecules, MNPs bear high sensitivity and selectivity towards the detection of target biomolecules, which means they are advantageous in biosensor development and lead to a more sensitive, rapid, and accurate identification and quantification of target analytes. Due to the abovementioned properties of functionalized MNPs and their unique magnetic characteristics, they could be employed in the creation of new POC devices, molecular logic gates, and new biomolecular-based biocomputing interfaces, which would build on new ideas and principles. The current review outlines the synthesis, surface coverage, and functionalization of MNPs, as well as recent advancements in magnetite-based biosensors for POC diagnostics and some perspectives in molecular logic, and it also contains some of our own results regarding the topic, which include synthetic MNPs, their application for sample preparation, and the design of fluorescent-based molecular logic gates.

Shifting the power: scale-up of access to point-of-care and self-testing for sexually transmitted infections in low-income and middle-income settings

Point-of-care (POC) testing for sexually transmitted infections (STIs) can provide complementary coverage to existing HIV testing services in LMICs. This review summarizes current and emerging technologies for detecting STIs in LMICs, with an emphasis on women, discharge-causing infections (chlamydia, gonorrhoea, trichomoniasis, and syphilis), true POC, self-testing, ethics, and economic considerations related to equitable access. The WHO have recently adapted guidelines for treatment of STIs in women that advise the use of true-POC or near-POC tests to improve case finding. The number of rapid, sensitive, and specific POC diagnostics for STIs has increased significantly over the past 10 years, although adoption of these in low-income and middle-income countries (LMICs) remains limited. Barriers to POC adoption by patients include the cost of tests, the inconvenience of lengthy clinic visits, low perceived risk, stigma, lack of partner notification, and lack of trust in healthcare providers. Lowering the cost of true POC lateral flow devices, interfacing these with digital or eHealth technologies, and enabling self-testing/self-sampling will overcome some of these barriers in LMICs. Ensuring linkage of diagnostic tests to subsequent care remains one of the major concerns about self-testing, irrespective of geography, although available evidence from HIV self-testing suggests that linkage to care is similar to that for facility-based testing. Increasing access to sensitive STI true POC tests will strengthen reproductive healthcare in LMICs. Although HIV self-testing is demonstrably useful in LMICs, there is an urgent need for randomized trials evaluating the utility and cost-effectiveness of similar tests for other sexually transmitted infections.

MagnEtophoretic Slider Assay (MeSA): A simple platform for point-of-care diagnostics

Infectious diseases account for millions of deaths each year. To reduce the number of infectious disease related deaths, diagnostic testing needs to be more accessible to patients in low-income countries as well as developed countries. Current diagnostic methods involve centralized laboratories, trained personnel, and are time-intensive, limiting translation to the point-of-care (POC). Microfluidic devices are a popular alternative for diagnostics due to reduced assay times, reduced sample volume, and lower cost. Microfluidic devices are small (&amp;lt;10 cm) and can perform complex assays. Microfluidic paper-based analytical devices (µPADs) are a popular approach to help translate diagnostics to the POC but historically suffer from poor sensitivity when compared to established laboratory methods. Magnetically labeling analytes allows samples to be sorted resulting in improved sensitivity and specificity. Microfluidic magnetophoresis is the process of manipulating magnetic particles in a magnetic field and offers the ability to wash and concentrate a sample during flow. However, until recently, magnetophoresis has not been used in conjunction with µPADs because magnetophoresis requires complex and expensive instrumentation to control flow. Coupling magnetophoresis with µPADs enables pump-free flow control, simple operation, and low cost. Early magnetophoresis µPADs showed detection limits similar to traditional methods but higher than targets for clinical use. In this work, we demonstrate a novel, simple MagnEtophoretic Slider Assay (MeSA) that is free of any external instrumentation and offers a new platform for POC diagnostics. We demonstrate the assay’s capability through biotin competitive assays and a sandwich immunoassay for E. coli detection. The calculated limit of detection for E. coli was 1.62 × 103 Colony Forming Units per mL (CFU/ml). The work described is a novel and simple microfluidic platform that has potential for a wide range of future applications.

Surface functionalized 3D printed metal structures as next generation recyclable SERS substrates.

Combining the design flexibility and rapid prototyping capabilities of additive manufacturing with photocatalytic and plasmonic functionalities is promising for the development of next-generation SERS applications such as point of care diagnostics and in situ monitoring of chemical reactions in fuels and chemical processing. Laser powder bed fusion (LPBF) is a well-matured additive manufacturing technique which generates metallic structures through localised melting and joining of metal powders using a laser. LPBF reduces material wastage during manufacturing, is applicable to a wide range of metals and alloys, and allows printing of complex internal structures. This feature article elaborates the use of soot templating, chemical vapour deposition and electroless plating techniques for grafting plasmonic and semiconductor nanoparticles on the surface of LPBF manufactured metallic substrates. The capability to fabricate different types of intricate metallic lattices using additive manufacturing is demonstrated and technical challenges in their adequate functionalization are elaborated. The developed methodology allows tailoring of the substrate structure, composition, morphology, plasmonic and photocatalytic activities and thus unveils a new class of recyclable SERS substrates.

Smart Microfluidics: Synergy of Machine Learning and Microfluidics in the Development of Medical Diagnostics for Chronic and Emerging Infectious Diseases.

The COVID-19 pandemic, emerging/re-emerging infections as well as other non-communicable chronic diseases, highlight the necessity of smart microfluidic point-of-care diagnostic (POC) devices and systems in developing nations as risk factors for infections, severe disease manifestations and poor clinical outcomes are highly represented in these countries. These POC devices are also becoming vital as analytical procedures executable outside of conventional laboratory settings are seen as the future of healthcare delivery. Microfluidics have grown into a revolutionary system to miniaturize chemical and biological experimentation, including disease detection and diagnosis utilizing μPads/paper-based microfluidic devices, polymer-based microfluidic devices and 3-dimensional printed microfluidic devices. Through the development of droplet digital PCR, single-cell RNA sequencing, and next-generation sequencing, microfluidics in their analogous forms have been the leading contributor to the technical advancements in medicine. Microfluidics and machine-learning-based algorithms complement each other with the possibility of scientific exploration, induced by the framework's robustness, as preliminary studies have documented significant achievements in biomedicine, such as sorting, microencapsulation, and automated detection. Despite these milestones and potential applications, the complexity of microfluidic system design, fabrication, and operation has prevented widespread adoption. As previous studies focused on microfluidic devices that can handle molecular diagnostic procedures, researchers must integrate these components with other microsystem processes like data acquisition, data processing, power supply, fluid control, and sample pretreatment to overcome the barriers to smart microfluidic commercialization.

Saliva-based microfluidic point-of-care diagnostic.

There has been a long-standing interest in point-of-care (POC) diagnostics as a tool to improve patient care because it can provide rapid, actionable results near the patient. Some of the successful examples of POC testing include lateral flow assays, urine dipsticks, and glucometers. Unfortunately, POC analysis is somewhat limited by the ability to manufacture simple devices to selectively measure disease specific biomarkers and the need for invasive biological sampling. Next generation POCs are being developed that make use of microfluidic devices to detect biomarkers in biological fluids in a non-invasive manner, addressing the above-mentioned limitations. Microfluidic devices are desirable because they can provide the ability to perform additional sample processing steps not available in existing commercial diagnostics. As a result, they can provide more sensitive and selective analysis. While most POC methods make use of blood or urine as a sample matrix, there has been a growing push to use saliva as a diagnostic medium. Saliva represents an ideal non-invasive biofluid for detecting biomarkers because it is readily available in large quantities and analyte levels reflect those in blood. However, using saliva in microfluidic devices for POC diagnostics is a relatively new and an emerging field. The overarching aim of this review is to provide an update on recent literature focused on the use of saliva as a biological sample matrix in microfluidic devices. We will first cover the characteristics of saliva as a sample medium and then review microfluidic devices that are developed for the analysis of salivary biomarkers.

Printable Graphene-Sustainable Elastomer-Based Cross Talk Free Sensor for Point of Care Diagnostics

Developing sensors for monitoring physiological parameters such as temperature and strain for point of care (POC) diagnostics is critical for better care of the patients. Various commercial sensors are available to get the job done; however, challenges like the structural rigidity of such sensors confine their usage. As an alternative, flexible sensors have been looked upon recently. In most cases, flexible sensors cannot discriminate the signals from different stimuli. While there have been reports on the printable sensors providing cross-talk-free solutions, research related to developing sensors from a sustainable source providing discriminability between signals is not well-explored. Herein, we report the development of a stencil printable composition made of graphene and epoxidized natural rubber. The stencil printability index was vetted using rheological studies. Post usage, the developed sensor was dissolved in an organic solvent at room temperature. This, along with the choice of a sustainable elastomer, warrants the minimization of electronic waste and carbon footprint. The developed material demonstrated good conformability with the skin and could perceive and decouple the signals from temperature and strain without inducing any crosstalks. Using a representative volume element model, a comparison between experimental findings and computation studies was made. The developed sensors demonstrated gauge factors of -506 and 407 in the bending strain regimes of 0-0.04% and 0.04%-0.09%, respectively, while the temperature sensitivity was noted to be -0.96%/°C. The printed sensors demonstrated a multifunctional sensing behavior for monitoring various active physiological parameters ranging from temperature, strain, pulse, and breathing to auditory responses. Using a Bluetooth module, various parameters like temperature and strain could be monitored seamlessly in a smart-phone. The current development would be crucial to open new avenues to fabricate crosstalk-free sensors from sustainable sources for POC diagnostics.

1172. Factors Associated With Febrile illnesses in Children in 27 Countries of Sub-Saharan Africa

Abstract Background Evidence on the relative importance of various factors associated with febrile illness in children and their heterogeneity across countries can inform the prevention, identification, and management of communicable diseases in resource-limited countries. Heatmap of odds ratios. Country-Specific Odds Ratios for 18 Factors Associated With Febrile illness From Multivariable Adjusted Models. Methods This cross-sectional study of 298 327 children aged 0 to 59 months assessed the strengths of associations of 18 factors with childhood fevers, using Demographic and Health Surveys (2010-2018) from 27 sub-Saharan African countries. A total of 7 direct factors (i.e., respiratory illness, diarrhea, breastfeeding initiation; vitamin A supplements; child's age; full vaccination; sex) and 11 indirect factors (household wealth; maternal education; maternal unemployment, water source; indoor pollution, stool disposal; antenatal care; family planning needs; maternal age, rural residence, and maternal marriage status) were assessed. Febrile illness was defined as the presence of fever in 2 weeks preceding the survey. Results Among the 298 327 children aged 0 to 59 months included in the analysis, the weighted prevalence of fever was 22.65% (95% CI, 22.31%-22.91%). In the pooled sample, respiratory illness was the strongest factor associated with fever in children (adjusted odds ratio [aOR], 5.46; 95% CI, 5.26-5.67; P &amp;lt; .0001), followed by diarrhea (aOR, 2.96; 95% CI, 2.85-3.08; P &amp;lt; .0001), poorest household wealth (aOR, 1.33; 95% CI,1.23-1.44; P &amp;lt; .0001), lack of maternal education (aOR, 1.25; 95% CI, 1.10-1.41; P &amp;lt; .0001), and delayed breastfeeding (aOR, 1.18; 95% CI, 1.14-1.22; P &amp;lt; .0001. Febrile illnesses were more prevalent in older children &amp;gt;6 months than those 6 months and younger. Conclusion In this study, respiratory illness, diarrhea, and socioeconomic conditions were the strongest factors associated with fevers in children of sub-Saharan Africa. Major causes of fevers in sub-Saharan Africa may mostly be attributed to respiratory infections and possibly viral—that may not be treated by antimalarial or antibiotics. Point of care diagnostics are needed to identify the pathogenic causes of respiratory infections to guide the clinical management of fevers in limited-resource countries. Disclosures All Authors: No reported disclosures.

Flexible and ultrathin waterproof conductive cellular membranes based on conformally gold-coated PVDF nanofibers and their potential as gas diffusion electrode

Nanofiber membranes (NFMs) coated with noble metals are intensively researched for various applications such as wearable electronics, environmental sensors, and point of care diagnostics. To achieve the desired functionality while minimizing costs, a combination of facile coating methods and accurate microstructural designs is required, but remains elusive. Herein, novel conductive and porous membranes are designed based on a facile and scalable approach to fabricating conformally coated gold layers on electrospun PVDF fibers (Au-PVDF-NFMs) via electroless plating. The deposition of a conformal and fully interconnected gold layer with an average thickness of circa 38 nm on the surface of nanofibers is confirmed by systematic characterizations. The high-conjunction gold layers endows a high electrical conductivity to the membranes, yielding a low sheet resistance of 1.2 Ω/sq. In addition, the membranes show integrated functionalities such as hydrophobicity and gas permeability. Notably, the NFMs also show excellent mechanical durability under both stretching and bending, with negligible conductivity losses after 1000 test cycles. Thanks to these properties, the Au-PVDF-NFMs demonstrates practical suitability as gas diffusion electrodes (GDEs) for electrochemical CO2 reduction. The Au-PVDF-NFMs exhibit a substantial Faradaic efficiency towards CO, as high as ∼ 85 % at −0.7 V vs reversible hydrogen electrode (RHE), and are able to reach current densities of 100 mA cm−2 at −0.95 V versus RHE.

Integrating Microfluidics and Electronics in Point-of-Care Diagnostics: Current and Future Challenges.

Point-of-Care (POC) diagnostics have gained increasing attention in recent years due to its numerous advantages over conventional diagnostic approaches. As proven during the recent COVID-19 pandemic, the rapidity and portability of POC testing improves the efficiency of healthcare services and reduces the burden on healthcare providers. There are hundreds of thousands of different applications for POC diagnostics, however, the ultimate requirement for the test is the same: sample-in and result-out. Many technologies have been implemented, such as microfluidics, semiconductors, and nanostructure, to achieve this end. The development of even more powerful POC systems was also enabled by merging multiple technologies into the same system. One successful example is the integration of microfluidics and electronics in POC diagnostics, which has simplified the sample handling process, reduced sample usage, and reduced the cost of the test. This review will analyze the current development of the POC diagnostic systems with the integration of microfluidics and electronics and discuss the future challenges and perspectives that researchers might have.

Emergence of infectious diseases and role of advanced nanomaterials in point-of-care diagnostics: a review

ABSTRACT Infectious outbreaks are the foremost global public health concern, challenging the current healthcare system, which claims millions of lives annually. The most crucial way to control an infectious outbreak is by early detection through point-of-care (POC) diagnostics. POC diagnostics are highly advantageous owing to the prompt diagnosis, which is economical, simple and highly efficient with remote access capabilities. In particular, utilization of nanomaterials to architect POC devices has enabled highly integrated and portable (compact) devices with enhanced efficiency. As such, this review will detail the factors influencing the emergence of infectious diseases and methods for fast and accurate detection, thus elucidating the underlying factors of these infections. Furthermore, it comprehensively highlights the importance of different nanomaterials in POCs to detect nucleic acid, whole pathogens, proteins and antibody detection systems. Finally, we summarize findings reported on nanomaterials based on advanced POCs such as lab-on-chip, lab-on-disc-devices, point-of-action and hospital-on-chip. To this end, we discuss the challenges, potential solutions, prospects of integrating internet-of-things, artificial intelligence, 5G communications and data clouding to achieve intelligent POCs.

A Review on PCR and POC-PCR - A Boon in the Diagnosis of COVID-19

Abstract: Ever since the global spread of covid 19, PCR predominantly took the lead in the diagnosis. It amplifies a particular DNA target sequence into millions of copies. To simplify the laboratory-dependent disease diagnosis, the point of care diagnostics (POC) paved the way for lab-on-a-chip-technology. Succeeding that, POC integrated with PCR stole the limelight. This review points out the various diagnostic methods of covid 19 based on PCR and POC-PCR along with its principles, and types clustered regularly interspaced short palindromic repeats (CRISPR) based assays for the rapid, accurate, and easier detection of covid 19.

Novel Electrochemical Biosensing for Detection of Neglected Tropical Parasites of Animal Origin: Recent Advances

AbstractParasitic diseases are among neglected disease of human and animals, especially in tropical and sub tropical regions. In the era of artificial intelligence, the novel biosensing diagnostic platform is needed for an early control measure implementation. This goal can be successfully achieved by onsite application of electrochemical biosensors. They are being developed towards point of care diagnostics; however commercial availability is scanty. The recent developments during last one decade in terms of the electrode surface modification for rapid diagnosis of important emerging/re‐emerging parasites is presented. The information would help future improvement in the electrochemical biosensing of parasites.

Point-of-Care Brain MRI: Preliminary Results from a Single-Center Retrospective Study.

Background Point-of-care (POC) MRI is a bedside imaging technology with fewer than five units in clinical use in the United States and a paucity of scientific studies on clinical applications. Purpose To evaluate the clinical and operational impacts of deploying POC MRI in emergency department (ED) and intensive care unit (ICU) patient settings for bedside neuroimaging, including the turnaround time. Materials and Methods In this preliminary retrospective study, all patients in the ED and ICU at a single academic medical center who underwent noncontrast brain MRI from January 2021 to June 2021 were investigated to determine the number of patients who underwent bedside POC MRI. Turnaround time, examination limitations, relevant findings, and potential CT and fixed MRI findings were recorded for patients who underwent POC MRI. Descriptive statistics were used to describe clinical variables. The Mann-Whitney U test was used to compare the turnaround time between POC MRI and fixed MRI examinations. Results Of 638 noncontrast brain MRI examinations, 36 POC MRI examinations were performed in 35 patients (median age, 66 years [IQR, 57-77 years]; 21 women), with one patient undergoing two POC MRI examinations. Of the 36 POC MRI examinations, 13 (36%) occurred in the ED and 23 (64%) in the ICU. There were 12 of 36 (33%) POC MRI examinations interpreted as negative, 14 of 36 (39%) with clinically significant imaging findings, and 10 of 36 (28%) deemed nondiagnostic for reasons such as patient motion. Of 23 diagnostic POC MRI examinations with comparison CT available, three (13%) demonstrated acute infarctions not apparent on CT scans. Of seven diagnostic POC MRI examinations with subsequent fixed MRI examinations, two (29%) demonstrated missed versus interval subcentimeter infarctions, while the remaining demonstrated no change. The median turnaround time of POC MRI was 3.4 hours in the ED and 5.3 hours in the ICU. Conclusion Point-of-care (POC) MRI was performed rapidly in the emergency department and intensive care unit. A few POC MRI examinations demonstrated acute infarctions not apparent at standard-of-care CT examinations. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Anzai and Moy in this issue.

MIP-based electrochemical sensor for direct detection of hepatitis C virus via E2 envelope protein

Hepatitis C is the most common liver disease caused by Hepatitis C virus (HCV), and can evolve into serious health problems e.g. cirrhosis and hepatocellular carcinoma. Nowadays, the initial stage of the disease cannot be practically diagnosed, representing thus an extremely important problem of modern public health care. This study is aimed at the development of a sensor for direct detection of HCV. The sensor utilizes a synthetic recognition element prepared by the technology of molecular imprinting and representing a molecularly imprinted polymer (MIP) having molecular recognition sites of HCV envelope protein E2 (E2-MIP). E2-MIP integrated into an electrochemical sensor platform allows quantitative evaluation of binding of free E2 protein as well as HCV-mimetic particles (HCV-MPs) in human plasma with LOD value of 4.6 × 10−4 ng/mL (for HCV-MPs). The developed electrochemical HCV sensor represents a simple, fast and inexpensive alternative for the existing methods of HCV detection and paves the way for the point-of care diagnostics of Hepatitis C.

A Low-Cost Cellulose-Based POC Device for Detection of COVID-19

Point-of-care diagnostic (POC) is of utmost importance for the fight against pandemics which provides easy, instant results right at your place. POC can transform healthcare management and create superior infrastructure. In POC, employing lateral flow assays (LFAs) can accelerate the assessment and shorten the treatment time. LFA is a small handheld device made from paper that controllably delivers the analyte without the need of an active pump to the detection area to produce the signal, generally coloured nanoparticles (Au, carbon).Conventional LFA device is made of four components, sample pad, conjugate pad, nitrocellulose membrane and absorbent pad arranged sequentially. At the sample pad, the analyte is dispensed. From here, the analyte moves to the conjugate pad and hybridizes with recognition antibodies (placed onto nanoparticles) to form analyte-antibody-gold nanoparticles conjugate. Further movement takes this to the nitrocellulose membrane. Here, other recognizant antibodies are placed at the test and control line to immobilize by forming the sandwich assay with the analyte-antibody-gold nanoparticles. The excess liquid is absorbed in the absorbent pad. From these components of the LFA device, nitrocellulose membrane and antibodies need replacements as they increase the device's overall cost. Cellulose paper holds promise to counter nitrocellulose membrane; however, the development of fabrication methods for cellulose paper-based LFA devices is needed. In comparison to antibodies, aptamers improve batch-to-batch variability, ruggedness, and longevity of LFA devices.This work describes the fabrication of half-strip cellulose paper (Whatman® Grade 4 filter paper) based LFA device exploiting aptamers as the recognition element for antigen detection. The covalent bonding of aptamers was achieved by NanoCheck-ATH® (NC) and p-phenylene disothiocyanate (PDITC). NC provides plentiful amine functional groups and constricts the test line width by covalently bonding aptamer to the NC region only. The chitosan-based NanoCheck on paper assists in realizing sharp test and control lines by providing the controlled surface for PDITC reaction through amine groups. PDITC functions as a linker between NC and aptamers. Finally, a proof-of-concept nucleocapsid protein of SARS-CoV-2 as an antigen detection was shown with the minimal detectable concentration down to ~20 ng/mL with excellent selectivity towards casein, BSA, and albumin. We envisage that using facile modification chemistry of NC, PDITC, and aptamers for antigen detection will allow the fabrication of paper-based LFA devices in a roll-to-roll setting and, thus, decrease the overall cost. The developed method is generic and can be adapted to detect other antigens to fight future pandemics.

Diagnostics for radiation injuries in large scale radio-nuclear accidents: Recent developments for a medical-management focused approach

During radiological or nuclear scenarios, a few to several tens of thousands of people can be affected. In a situation like that, it is essential identifying unexposed (to avoid absorbance of limited clinical resources), low exposed (not requiring immediate care but in need of surveillance for later developing health effects), and highly exposed individuals who will suffer from life-threatening acute health effects summarized into the acute radiation syndrome/sickness (ARS). An early hospitalization and early treatment will have a high impact on the ARS outcome. Hence, early and high-throughput diagnostics in specialized facilities, as well as point of care diagnostics, are required. Several approaches dealing with the support of medical management are known. Those comprise physical, clinical, and biological dosimetry. None of these approaches alone is ideal, and only a combination will cover different scenarios and different requirements. In this situation, it is useful revisiting the core task - Medical Management of irradiated individuals. Different layers of complexity/challenges have to be considered. They start with radiation exposure followed by radiation-induced biological alterations. These biological changes might convert into useful biomarkers located downstream of the exposure on a time scale closer to the effect (the ARS). As a final layer of complexity, these biomarkers of effect prediction have to be converted into clinically relevant information to facilitate patients’ treatment by clinicians understanding the prediction. The Bundeswehr Institute of Radiobiology (BIR) established two biomarker tools, which seem to integrate radiation exposure and biological processes for predicting clinical outcomes (hematological ARS, H-ARS severity). These tools bridge the gap and provide clinicians with comprehensive information for the treatment of potentially irradiated individuals. We, herein, describe the four layers of complexity and introduce the two tools, namely, the H-Module and a suggested gene expression combination for H-ARS prediction.