Point of Care Diagnostics in Resource-Limited Settings: A Review of the Present and Future of PoC in Its Most Needed Environment

Point-of-care biochemistry for primary healthcare in low-middle income countries: a qualitative inquiry

BACKGROUND

Access to essential diagnostics is crucial for primary healthcare (PHC) in low-and-middle income countries (LMICs). Many LMICs have invested in equipping PHC with point-of-care (PoC) diagnostics for infectious diseases, however there has been no similar investment to improve PHC capacities for clinical chemistry. The biochemistry gap is among the deterrents to universal health coverage.

METHODS

A social sciences project was conducted with the aim to understand the key PHC stakeholders' insights on the pertinence of PoC biochemistry for PHC in LMICs. Data generation was conducted between July-November 2023 in Mongolia, Nigeria and Peru. Decision-makers in healthcare delivery, healthcare professionals, and patient and community advocates were engaged using a combination of sampling techniques. Unstructured individual and group conversations, and non-participant observation were conducted. Analysis involved an inductive line-by-line coding on printed transcripts, followed by a deductive coding and theme-by-theme analysis on digitized transcripts.

RESULTS

Fifteen, 51 and 20 informants from Mongolia, Nigeria and Peru, respectively, participated. Fifty-five of the 94 informants were female. Most informants considered that PoC biochemistry in PHC would be pertinent, from a clinical and a resources-saving perspective. Those households that currently bear the burden of referrals (i.e., the poor, the bedridden, the older adults) would benefit the most from the deployment of PoC biochemistry for essential biochemistry parameters. Improved access to PoC glycated hemoglobin (HbA1c), lipid, liver and kidney profile was perceived as helpful to inform clinicians' decision-taking. The value of PoC biochemistry for the management of noncommunicable diseases (diabetes, hypertension) and infectious conditions (dengue, malaria, tuberculosis), to improve child health outcomes (severe dehydration in children with diarrhea and/or malnutrition) and to reduce preventable causes of death (dengue-related renal failure) was highlighted.

CONCLUSIONS

PoC biochemistry holds potential to revert the impact that the biochemistry gap has for patient care in some LMICs' PHC settings. PoC equipment for parameters such as HbA1c, urea, creatinine or electrolytes could enhance community-level management of preventable causes of mortality, improve service delivery for patients affected by locally-prevalent infectious conditions, and improve the psychosocial and economic wellbeing of patients facing the burden of referrals to remote biochemistry-equipped centers.

TRIAL REGISTRATION

Not applicable.

Paper-Based DNA Biosensor for Rapid and Selective Detection of miR-21

Cancer is the second leading cause of death globally, with 9.7 million fatalities in 2022. While routine screenings are vital for early detection, healthcare disparities persist, highlighting the need for equitable solutions. Recent advancements in cancer biomarker identification, particularly microRNAs (miRs), have improved early detection. MiR-21 is notably overexpressed in various cancers and can be a valuable diagnostic tool. Traditional detection methods, though accurate, are costly and complex, limiting their use in resource-limited settings. Paper-based electrochemical biosensors offer a promising alternative, providing cost-effective, sensitive, and rapid diagnostics suitable for point-of-care use. This study introduces an innovative electrochemical paper-based biosensor that leverages gold inkjet printing for the quantitative detection of miR-21. The biosensor, aimed at developing cost-effective point-of-care devices for low-resource settings, uses thiolated self-assembled monolayers to immobilize single-stranded DNA-21 (ssDNA-21) on electrodeposited gold nanoparticles (AuNPs) on the printed gold surface, facilitating specific miR-21 capture. The hybridization of ssDNA-21 with miR-21 increases the anionic barrier density, impeding electron transfer from the redox probe and resulting in a current suppression that correlates with miR-21 concentration. The biosensor exhibited a linear detection range from 1 fM to 1 nM miR-21 with a sensitivity of 7.69 fM µA-1 cm2 and a rapid response time (15 min). With a low detection limit of 0.35 fM miR-21 in serum, the biosensor also demonstrates excellent selectivity against interferent species. This study introduces an electrochemical paper-based biosensor that uses gold inkjet printing to precisely detect miR-21, a key biomarker overexpressed in various cancers. This innovative device highlights the potential for cost-effective, accessible cancer diagnostics in underserved areas.

Diagnostics for detection and surveillance of priority epidemic-prone diseases in Africa: an assessment of testing capacity and laboratory strengthening needs

In 2023, Africa experienced 180 public health emergencies, of which 90% were infectious diseases and 75% were related to zoonotic diseases. Testing capacity for epidemic-prone diseases is essential to enable rapid and accurate identification of causative agents, and for action to prevent disease spread. Moreover, testing is pivotal in monitoring disease transmission, evaluating public health interventions and informing targeted resource allocation during outbreaks. An online, self-assessment survey was conducted in African Union Member States to identify major challenges in testing for epidemic-prone diseases. The survey assessed current capacity for diagnosing priority epidemic-prone diseases at different laboratory levels. It explored challenges in establishing and maintaining testing capacity to improve outbreak response and mitigate public health impact. Survey data analysed diagnostic capacity for priority infectious diseases, diagnostic technologies in use, existing surveillance programmes and challenges limiting diagnostic capacity, by country. The survey result from 15 Member States who responded to the survey, showed high variability in testing capacity and technologies across countries and diverse factors limiting testing capacity for certain priority diseases like dengue and Crimean-Congo haemorrhagic fever. At the same time diagnostic capacity is better for coronavirus disease 2019 (COVID-19), polio, and measles due to previous investments. Unfortunately, many countries are not utilizing multiplex testing, despite its potential to improve diagnostic access. The challenges of limited laboratory capacity for testing future outbreaks are indeed significant. Recent disease outbreaks in Africa have underscored the urgent need to strengthen diagnostic capacity and introduce cost-effective technologies. Small sample sizes and differing disease prioritisation within each country limited the analysis. These findings suggest the benefits of evaluating laboratory testing capacity for epidemic-prone diseases and highlight the importance of effectively addressing challenges to detect diseases and prevent future pandemics.

Enhanced CRISPR/Cas-Based Immunoassay through Magnetic Proximity Extension and Detection

Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-associated systems have recently emerged as a focal point for developing next-generation molecular diagnosis, particularly for nucleic acid detection. However, the detection of proteins is equally critical across diverse applications in biology, medicine, and the food industry, especially for diagnosing and prognosing diseases like cancer, Alzheimer's and cardiovascular conditions. Despite recent efforts to adapt CRISPR/Cas systems for protein detection with immunoassays, these methods typically achieved sensitivity only in the femtomolar to picomolar range, underscoring the need for enhanced detection capabilities. To address this, we developed CRISPR-AMPED, an innovative CRISPR/Cas-based immunoassay enhanced by magnetic proximity extension and detection. This approach combines proximity extension assay (PEA) with magnetic beads that converts protein into DNA barcodes for quantification with effective washing steps to minimize non-specific binding and hybridization, therefore reducing background noise and increasing detection sensitivity. The resulting DNA barcodes are then detected through isothermal nucleic acid amplification testing (NAAT) using recombinase polymerase amplification (RPA) coupled with the CRISPR/Cas12a system, replacing the traditional PCR. This integration eliminates the need for thermocycling and bulky equipment, reduces amplification time, and provides simultaneous target and signal amplification, thereby significantly boosting detection sensitivity. CRISPR-AMPED achieves attomolar level sensitivity, surpassing ELISA by over three orders of magnitude and outperforming existing CRISPR/Cas-based detection systems. Additionally, our smartphone-based detection device demonstrates potential for point-of-care applications, and the digital format extends dynamic range and enhances quantitation precision. We believe CRISPR-AMPED represents a significant advancement in the field of protein detection.

Impact of Hepatitis B Virus Point-of-care DNA Viral Load Testing Compared With Laboratory-based Standard-of-care Approaches on Uptake of HBV Viral Load Testing, Treatment, and Turnaround Times: A Systematic Review and Meta-analysis

Background

Point-of-care (PoC) hepatitis B virus (HBV) DNA viral load (VL) assays represent an alternative to laboratory-based standard-of-care (SoC) VL assays to accelerate diagnosis and treatment. We evaluated the impact of using PoC versus SoC approaches on the uptake of VL testing, treatment, and turnaround times from testing to treatment across the HBV care cascade.

Methods

We searched 5 databases, 6 conference websites, and contacted manufacturers for unpublished reports, for articles with or without a comparator (SoC VL testing), and had data on the uptake of VL testing, treatment, or turnaround times between hepatitis B surface antigen (HBsAg) testing, VL testing, and treatment in the cascade. We performed a random-effects meta-analysis on rates of VL testing and treatment initiation.

Results

Six studies, composing 9 arms, were included. Three PoC arms reported less than 1 day between screening for HBsAg positivity and VL testing, and the other one (2 arms) reported it between 7 and 11 days. Five arms reported the time to available VL test results (<1 day). Three studies reported 1-8 days between VL testing results and treatment initiation. Two studies reported the turnaround times between a positive HBsAg screening and treatment initiation (the same day and 27 days). Overall, 84.1% of those with HBsAg positivity were tested for DNA VL and 88.3% of eligible people initiated treatment.

Conclusions

HBV PoC DNA testing appears to be associated with a turnaround time of <1 day for receipt of VL results and appears associated with high rates of DNA testing and initiation of treatment among those eligible.

Clinical Trials Registration

PROSPERO CRD42023398440.

Mobile-linked point-of-care diagnostics in community-based healthcare: a scoping review of user experiences

BACKGROUND

While mobile-linked point-of-care diagnostics may circumvent geographical and temporal barriers to efficient communication, the use of such technology in community settings will depend on user experience. We conducted a scoping review to systematically map evidence on user experiences of mobile-linked point-of-care diagnostics in community healthcare settings published from the year 2016 up to the year 2022.

METHODOLOGY

We conducted a comprehensive search of the following electronic databases: Scopus, Web of Science, and EBSCOhost (Medline, CINAHL, Africa-wide, Academic Search Complete). The inter-reviewer agreement was determined using Cohen's kappa statistic. Data quality was appraised using the mixed method appraisal tool version 2018, and the results were reported according to the preferred reporting items for systematic reviews and meta-analyses for scoping reviews (PRISMA-ScR).

RESULTS

Following the abstract and full article screening, nine articles were found eligible for inclusion in data extraction. Following the quality appraisal, one study scored 72.5%, one study scored 95%, and the remaining seven studies scored 100%. Inter-rater agreement was 83.54% (Kappa statistic = 0.51, p < 0.05). Three themes emerged from the articles: approaches to implementing mobile-linked point-of-care diagnostics, user engagement in community-based healthcare settings, and limited user experiences in mobile-linked point-of-care diagnostics. User experiences are key to the sustainable implementation of mobile-linked point-of-care diagnostics. User experiences have been evaluated in small community healthcare settings. There is limited evidence of research aimed at evaluating the usability of mobile-linked diagnostics at the community level.

CONCLUSION

More studies are needed to assess the user experience of mobile-linked diagnostics in larger communities. This scoping review revealed gaps that need to be addressed to improve user experiences of mobile-linked diagnostics, including language barriers, privacy issues, and clear instructions.

The social lives of point-of-care tests in low- and middle-income countries: a meta-ethnography

Point-of-care tests (POCTs) have become technological solutions for many global health challenges. This meta-ethnography examines what has been learned about the 'social lives' of POCTs from in-depth qualitative research, highlighting key social considerations for policymakers, funders, developers and users in the design, development and deployment of POCTs. We screened qualitative research examining POCTs in low- and middle-income countries and selected 13 papers for synthesis. The findings illuminate five value-based logics-technological autonomy, care, scalability, rapidity and certainty-shaping global health innovation ecosystems and their entanglement with health systems. Our meta-ethnography suggests that POCTs never achieve the technological autonomy often anticipated during design and development processes. Instead, they are both embedded in and constitutive of the dynamic relationships that make up health systems in practice. POCTs are often imagined as caring commodities; however, in use, notions of care inscribed in these devices are constantly negotiated and transformed in relation to multiple understandings of care. POCTs promise to standardize care across scale, yet our analysis indicates nonstandard processes, diagnoses and treatment pathways as essential to 'fluid technologies' rather than dangerous aberrations. The rapidity of POCTs is constructed and negotiated within multiple distinct temporal registers, and POCTs operate as temporal objects that can either speed up or slow down experiences of diagnosis and innovation. Finally, while often valued as epistemic tools that can dispel diagnostic uncertainty, these papers demonstrate that POCTs contribute to new forms of uncertainty. Together, these papers point to knowledge practices as multiple, and POCTs as contributing to, rather than reducing, this multiplicity. The values embedded in POCTs are fluid and contested, with important implications for the kind of care these tools can deliver. These findings can contribute to more reflexive approaches to global health innovation, which take into account limitations of established global health logics, and recognize the socio-technical complexity of health systems.

Point-of-care C-reactive protein measurement by community health workers safely reduces antimicrobial use among children with respiratory illness in rural Uganda: A stepped wedge cluster randomized trial

BACKGROUND

Acute respiratory illness (ARI) is one of the most common reasons children receive antibiotic treatment. Measurement of C-reaction protein (CRP) has been shown to reduce unnecessary antibiotic use among children with ARI in a range of clinical settings. In many resource-constrained contexts, patients seek care outside the formal health sector, often from lay community health workers (CHW). This study's objective was to determine the impact of CRP measurement on antibiotic use among children presenting with febrile ARI to CHW in Uganda.

METHODS AND FINDINGS

We conducted a cross-sectional, stepped wedge cluster randomized trial in 15 villages in Bugoye subcounty comparing a clinical algorithm that included CRP measurement by CHW to guide antibiotic treatment (STAR Sick Child Job Aid [SCJA]; intervention condition) with the Integrated Community Care Management (iCCM) SCJA currently in use by CHW in the region (control condition). Villages were stratified into 3 strata by altitude, distance to the clinic, and size; in each stratum, the 5 villages were randomly assigned to one of 5 treatment sequences. Children aged 2 months to 5 years presenting to CHW with fever and cough were eligible. CHW conducted follow-up assessments 7 days after the initial visit. Our primary outcome was the proportion of children who were given or prescribed an antibiotic at the initial visit. Our secondary outcomes were (1) persistent fever on day 7; (2) development of prespecified danger signs; (3) unexpected visits to the CHW; (4) hospitalizations; (5) deaths; (6) lack of perceived improvement per the child's caregiver on day 7; and (7) clinical failure, a composite outcome of persistence of fever on day 7, development of danger signs, hospitalization, or death. The 65 participating CHW enrolled 1,280 children, 1,220 (95.3%) of whom had sufficient data. Approximately 48% (587/1,220) and 52% (633/1,220) were enrolled during control (iCCM SCJA) and intervention periods (STAR SCJA), respectively. The observed percentage of children who were given or prescribed antibiotics at the initial visit was 91.8% (539/587) in the control periods as compared to 70.8% (448/633) during the intervention periods (adjusted prevalence difference -24.6%, 95% CI: -36.1%, -13.1%). The odds of antibiotic prescription by the CHW were over 80% lower in the intervention as compared to the control periods (OR 0.18, 95% CI: 0.06, 0.49). The frequency of clinical failure (iCCM SCJA 3.9% (23/585) v. STAR SCJA 1.8% (11/630); OR 0.41, 95% CI: 0.09, 1.83) and lack of perceived improvement by the caregiver (iCCM SCJA 2.1% (12/584) v. STAR SCJA 3.5% (22/627); OR 1.49, 95% CI: 0.37, 6.52) was similar. There were no unexpected visits or deaths in either group within the follow-up period.

CONCLUSIONS

Incorporating CRP measurement into iCCM algorithms for evaluation of children with febrile ARI by CHW in rural Uganda decreased antibiotic use. There is evidence that this decrease was not associated with worse clinical outcomes, although the number of adverse events was low. These findings support expanded access to simple, point-of-care diagnostics to improve antibiotic stewardship in rural, resource-constrained settings where individuals with limited medical training provide a substantial proportion of care.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05294510. The study was reviewed and approved by the University of North Carolina Institutional Review Board (#18-2803), Mbarara University of Science and Technology Research Ethics Committee (14/03-19), and Uganda National Council on Science and Technology (HS 2631).

Molecular Point-of-Care Assay Development: Design and Considerations

Molecular diagnostic point-of-care (MDx POC) testing is gaining momentum and is increasingly important for infectious disease detection and monitoring, as well as other diagnostic areas such as oncology. Molecular testing has traditionally required high-complexity laboratories. Laboratory testing complexity is determined by utilizing the Clinical Laboratory Improvement Amendments of 1988 (CLIA) Categorization Criteria scorecard, utilizing seven criteria that are scored on a scale of one to three. Previously, most commercially available point-of-care (POC) tests use other analytes and technologies that were not found to be highly complex by the CLIA scoring system. However, during the COVID-19 pandemic, MDx POC testing became much more prominent. Utilization during the COVID-19 pandemic has demonstrated that MDx POC testing applications can have outstanding advantages compared to available non-molecular POC diagnostic tests. This article introduces MDx POC testing to students, technologists, researchers, and others, providing a general algorithm for MDx POC test development. This algorithm is an introductory, step-by-step decision tree for defining a molecular POC diagnostic device meeting the functional requirements for a desired application. The technical considerations driving the decision-making include nucleic acid selection method (DNA, RNA), extraction methods, sample preparation, number of targets, amplification technology, and detection method. The scope of this article includes neither higher-order multiplexing, nor quantitative molecular analysis. This article covers key application considerations, such as sensitivity, specificity, turnaround time, and shipping/storage requirements. This article provides an overall understanding of the best resources and practices to use when developing a MDx POC assay that may be a helpful resource for readers without extensive molecular testing experience as well as for those who are already familiar with molecular testing who want to increase MDx availability at the POC. © 2024 Wiley Periodicals LLC.

Sustainable solutions to barriers of point-of-care diagnostic testing services in health facilities without laboratories in the bono region, Ghana: a qualitative study

BACKGROUND

A sustainable point-of-care (POC) diagnostic testing implementation in low-resourced facilities enhances quick diagnostic investigation and halts unnecessary referrals. This study identified the barriers impeding the implementation of POC diagnostic testing in health facilities without laboratories in the Bono Region of Ghana; as well as explored potential solutions that could enhance the accessibility and effectiveness of POC diagnostic testing, ultimately improving the quality of healthcare delivery.

METHODS

A total of twenty-eight participants were purposively selected from health facilities in low-resourced settings in the Bono Region for a descriptive qualitative study. Of the twenty-eight participants, seventeen including ten healthcare providers from CHPS facilities, six district health depot managers, and one regional depot manager were engaged in in-depth interviews. Additional eleven including nine healthcare providers and two district depot managers were also engaged in focus group discussions. NVivo version 12 software was employed for condensation, labelling, and grouping of themes. Data was analysed narratively.

RESULTS

Work overloads, limited POC testing services, stock-outs of POC tests at the facilities, and supply-related challenges of POC test kits were identified as major barriers to POC testing services. To solve these barriers, adequate funding, an effective delivery system, stakeholders' engagement and advocacy, and in-service and refresher training courses were suggested as potential solutions to POC diagnostic testing services implementation by the stakeholders.

CONCLUSIONS

This study's findings emphasize the need to address the barriers hindering the implementation of POC diagnostic testing in health facilities without laboratories in the Bono Region of Ghana. The suggested solutions provide a roadmap for improving the accessibility and effectiveness of POC testing, which has the potential to enhance the quality of healthcare delivery, reduce unnecessary referrals, and ultimately improve patient health outcomes in underserved settings.

Point-of-care diagnostics for infection and antimicrobial resistance in sub-Saharan Africa: A narrative review

OBJECTIVES

Sub-Saharan African (SSA) countries are severely impacted by antimicrobial resistance (AMR). Due to gaps in access to diagnostics in SSA, the true extent of AMR remains unknown. This diagnostic gap affects patient management and leads to significant antimicrobial overuse. This review explores how point-of-care (POC) testing for pathogen identification and AMR may be used to close the diagnostic gap in SSA countries.

METHODS

A narrative review exploring current clinical practice and novel developments in the field of POC testing for infectious diseases and AMR.

RESULTS

POC assays for identification of various pathogens have been successfully rolled out in SSA countries. While implementation studies have mostly highlighted impressive test performance of POC assays, there is limited data on the impact of implementation on clinical outcomes and cost-effectiveness. We did not encounter local studies of host-directed POC assays relevant to AMR. Novel POC assays using real-time polymerase chain reaction, isothermal amplification, microfluidics, and other technologies are in various stages of development.

CONCLUSIONS

Available literature shows that POC testing for AMR applications is implementable in SSA and holds the potential to reduce the diagnostic gap. Implementation will require effective regulatory pathways, incorporation of POC testing in clinical and laboratory guidelines, and adequate value capture in existing health financing models.

Analytical performances of a point-of-care loop-mediated isothermal amplification assay to detect Group B Streptococcus in intrapartum pregnant women living in the Democratic Republic of the Congo

OBJECTIVES

Group B Streptococcus (GBS) is the leading infectious cause of stillbirth and neonatal morbidity and mortality in sub-Saharan Africa.

METHODS

Vaginal and rectovaginal swab samples were obtained from 274 intrapartum pregnant women in the Democratic Republic of the Congo to be analyzed for GBS DNA detection in parallel by the point-of-care BIOSYNEX AMPLIFLASH® GBS assay (Biosynex SA, Illkirch-Graffenstaden, France) and by reference quantitative polymerase chain reaction (qPCR).

RESULTS

Rectovaginal swabbing, nearly two-fold more positive for GBS than vaginal swabbing alone, showed a high prevalence of GBS DNA positivity in 20.1% of eligible intrapartum pregnant women. In the event of significant bacterial carriage (i.e., cycle threshold ≤33 by reference qPCR), the AMPLIFLASH® GBS assay with rectovaginal swabbing showed high sensitivity (98.1%) and specificity (100.0%) for GBS DNA detection, with excellent concordance, reliability, and accuracy with the reference qPCR, and positive predictive values and negative predictive values above 99.0%.

CONCLUSIONS

The study demonstrates a high rate of female rectogenital GBS colonization in pregnant Congolese women. The AMPLIFLASH® GBS assay harbored excellent analytical performances in the field, which makes it suitable to be used as point-of-care molecular assay in various hospital and non-hospital settings where rapid diagnosis of GBS is necessary.

Engineered two-dimensional nanomaterials based diagnostics integrated with internet of medical things (IoMT) for COVID-19

More than four years have passed since an inimitable coronavirus disease (COVID-19) pandemic hit the globe in 2019 after an uncontrolled transmission of the severe acute respiratory syndrome (SARS-CoV-2) infection. The occurrence of this highly contagious respiratory infectious disease led to chaos and mortality all over the world. The peak paradigm shift of the researchers was inclined towards the accurate and rapid detection of diseases. Since 2019, there has been a boost in the diagnostics of COVID-19 via numerous conventional diagnostic tools like RT-PCR, ELISA, etc., and advanced biosensing kits like LFIA, etc. For the same reason, the use of nanotechnology and two-dimensional nanomaterials (2DNMs) has aided in the fabrication of efficient diagnostic tools to combat COVID-19. This article discusses the engineering techniques utilized for fabricating chemically active E2DNMs that are exceptionally thin and irregular. The techniques encompass the introduction of heteroatoms, intercalation of ions, and the design of strain and defects. E2DNMs possess unique characteristics, including a substantial surface area and controllable electrical, optical, and bioactive properties. These characteristics enable the development of sophisticated diagnostic platforms for real-time biosensors with exceptional sensitivity in detecting SARS-CoV-2. Integrating the Internet of Medical Things (IoMT) with these E2DNMs-based advanced diagnostics has led to the development of portable, real-time, scalable, more accurate, and cost-effective SARS-CoV-2 diagnostic platforms. These diagnostic platforms have the potential to revolutionize SARS-CoV-2 diagnosis by making it faster, easier, and more accessible to people worldwide, thus making them ideal for resource-limited settings. These advanced IoMT diagnostic platforms may help with combating SARS-CoV-2 as well as tracking and predicting the spread of future pandemics, ultimately saving lives and mitigating their impact on global health systems.

Lessons from the pandemic: new best practices in selecting molecular diagnostics for point-of-care testing of infectious diseases in sub-Saharan Africa

INTRODUCTION

Point-of-care molecular diagnostics offer solutions to the limited diagnostic availability and accessibility in resource-limited settings. During the COVID-19 pandemic, molecular diagnostics became essential tools for accurate detection and monitoring of SARS-CoV-2. The unprecedented demand for molecular diagnostics presented challenges and catalyzed innovations which may provide lessons for the future selection of point-of-care molecular diagnostics.

AREAS COVERED

We searched PubMed from January 2020 to August 2023 to identify lessons learned from the COVID-19 pandemic which may impact the selection of point-of-care molecular diagnostics for future use in sub-Saharan Africa. We evaluated this in the context of REASSURED criteria (Real-time connectivity; Ease of specimen collection; Affordable; Sensitive; Specific; User-friendly; Rapid and robust; Equipment free; and Deliverable to users at the point of need) for point-of-care diagnostics for resource-limited settings.

EXPERT OPINION

The diagnostic challenges and successes during the COVID-19 pandemic affirmed the importance of the REASSURED criteria but demonstrated that these are not sufficient to ensure new diagnostics will be appropriate for public health emergencies. Capacity for rapid scale-up of diagnostic testing and transferability of assays, data, and technology are also important, resulting in updated REST-ASSURED criteria. Few diagnostics will meet all criteria, and trade-offs between criteria will need to be context-specific.

FlashPCR: Revolutionising qPCR by Accelerating Amplification through Low ∆T Protocols

Versatility, sensitivity, and accuracy have made the real-time polymerase chain reaction (qPCR) a crucial tool for research, as well as diagnostic applications. However, for point-of-care (PoC) use, traditional qPCR faces two main challenges: long run times mean results are not available for half an hour or more, and the requisite high-temperature denaturation requires more robust and power-demanding instrumentation. This study addresses both issues and revises primer and probe designs, modified buffers, and low ∆T protocols which, together, speed up qPCR on conventional qPCR instruments and will allow for the development of robust, point-of-care devices. Our approach, called "FlashPCR", uses a protocol involving a 15-second denaturation at 79 °C, followed by repeated cycling for 1 s at 79 °C and 71 °C, together with high Tm primers and specific but simple buffers. It also allows for efficient reverse transcription as part of a one-step RT-qPCR protocol, making it universally applicable for both rapid research and diagnostic applications.

Wireless Detection of Trace Ammonia: A Chronic Kidney Disease Biomarker

Elevated levels of ammonia in breath can be linked to medical complications, such as chronic kidney disease (CKD), that disturb the urea balance in the body. However, early stage CKD is usually asymptomatic, and mass screening is hindered by high instrumentation and operation requirements and accessible and reliable detection methods for CKD biomarkers, such as trace ammonia in breath. Enabling methods would have significance in population screening for early stage CKD patients. We herein report a method to effectively immobilize transition metal selectors in close proximity to a single-walled carbon nanotube (SWCNT) surface using pentiptycene polymers containing metal-chelating backbone structures. The robust and modular nature of the pentiptycene metallopolymer/SWCNT complexes creates a platform that accelerates sensor discovery and optimization. Using these methods, we have identified sensitive, selective, and robust copper-based chemiresistive ammonia sensors that display low parts per billion detection limits. We have added these hybrid materials to the resonant radio frequency circuits of commercial near-field communication (NFC) tags to achieve robust wireless detection of ammonia at physiologically relevant levels. The integrated devices offer a noninvasive and cost-effective approach for early detection and monitoring of CKD.

Military Medicine and Medical Research as a Source of Inspiration and Innovation to Solve National Security and Health Challenges in the 21st Century

The history of military medicine and research is rife with examples of novel treatments and new approaches to heal and cure soldiers and others impacted by war's devastation. In the 21st century, new threats, like climate change, are combined with traditional threats, like geopolitical conflict, to create novel challenges for our strategic interests. Extreme and inaccessible environments provide heightened risks for warfighter exposure to dangerous bacteria, viruses, and fungi, as well as exposure to toxic substances and extremes of temperature, pressure, or both providing threats to performance and eroding resilience. Back home, caring for our veterans is also a health-care priority, and the diseases of veterans increasingly overlap with the health needs of an aging society. These trends of climate change, politics, and demographics suggest performance evaluation and resilience planning and response are critical to assuring both warfighter performance and societal health. The Cleveland ecosystem, comprising several hospitals, a leading University, and one of the nation's larger Veteran's Health Administration systems, is ideal for incubating and understanding the response to these challenges. In this review, we explore the interconnections of collaborations between Defense agencies, particularly Air Force and Army and academic medical center-based investigators to drive responses to the national health security challenges facing the United States and the world.

Flexible and Innovative Connectivity Solution to Support National Decentralized Infectious Diseases Point-of-Care Testing Programs in Primary Health Services: Descriptive Evaluation Study

BACKGROUND

Molecular point-of-care (POC) testing for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV) has been available in regional and remote primary health services in Australia as part of a decentralized POC testing program since 2016 and for SARS-CoV-2 from 2020. As there was no suitable existing connectivity infrastructure to capture and deliver POC test results to a range of end users, a new system needed to be established.

OBJECTIVE

The aim of the study is to design, implement, and optimize a connectivity system to meet clinical management, analytical quality management, and public health surveillance needs.

METHODS

We used commercially available e-messaging technology coupled with adapted proprietary software to integrate a decentralized molecular POC testing platform (GeneXpert) in primary health services and interface with end-user databases. This connectivity infrastructure was designed to overcome key barriers to the implementation, integration, and monitoring of these large multijurisdictional infectious disease POC testing networks. Test result messages were tailored to meet end-user needs. Using centrally captured deidentified data, we evaluated the time to receipt of test results and completeness of accompanying demographic data.

RESULTS

From January 2016 to April 2020, we operationalized the system at 31 health services across 4 jurisdictions and integrated with 5 different patient management systems to support the real-time delivery of 29,356 CT/NG and TV test results to designated recipients (patient management system and local clinical and central program databases). In 2019, 12,105 CT/NG and TV results were delivered, and the median time to receipt of results was 3.2 (IQR 2.2-4.6) hours, inclusive of test runtime. From May 2020 to August 2022, we optimized the system to support rapid scale-up of SARS-CoV-2 testing (105 services; 6 jurisdictions; 71,823 tests) and additional sexually transmissible infection testing (16,232 tests), including the electronic disease-specific notifications to jurisdictional health departments and alerts for connectivity disruption and positive results. In 2022, 19,355 results were delivered with an overall median transmission time of 2.3 (IQR 1.4-3.1) hours, 2.2 (IQR 1.2-2.3) hours for SARS-CoV-2 (n=16,066), 3.0 (IQR 2.0-4.0) hours for CT/NG (n=1843), and 2.6 (IQR 1.5-3.8) hours for TV (n=1446). Demographic data (age, sex, and ethnicity) were completed for 99.5% of test results in 2022.

CONCLUSIONS

This innovative connectivity system designed to meet end-user needs has proven to be sustainable, flexible, and scalable. It represents the first such system in Australia established independent of traditional pathology providers to support POC testing in geographically dispersed remote primary health services. The system has been optimized to deliver real-time test results and has proven critical for clinical, public health, and quality management. The system has significantly supported equitable access to rapid diagnostics for infectious diseases across Australia, and its design is suitable for onboarding other POC tests and testing platforms in the future.

Point-of-care testing in private pharmacy and drug retail settings: a narrative review

BACKGROUND

Point-of-care testing (POCT) using rapid diagnostic tests for infectious disease can potentially guide appropriate use of antimicrobials, reduce antimicrobial resistance, and economise use of healthcare resources. POCT implementation in private retail settings such as pharmacies and drug shops could lessen the burden on public healthcare. We performed a narrative review on studies of POCTs in low- and middle-income countries (LMICs), and explored uptake, impact on treatment, and feasibility of implementation.

METHODS

We searched MEDLINE/PubMed for interventional studies on the implementation of POCT for infectious diseases performed by personnel in private retail settings. Data were extracted and analysed by two independent reviewers.

RESULTS

Of the 848 studies retrieved, 23 were included in the review. Studies were on malaria (19/23), malaria and pneumonia (3/23) or respiratory tract infection (1/23). Nine randomised controlled studies, four controlled, non-randomised studies, five uncontrolled interventions, one interventional pre-post study, one cross-over interventional study and three retrospective analyses of RCTs were included. Study quality was poor. Overall, studies showed that POCT can be implemented successfully, leading to improvements in appropriate treatment as measured by outcomes like adherence to treatment guidelines. Despite some concerns by health workers, customers and shop providers were welcoming of POCT implementation in private retail settings. Main themes that arose from the review included the need for well-structured training with post-training certification covering guidelines for test-negative patients, integrated waste management, community sensitization and demand generation activities, financial remuneration and pricing schemes for providers, and formal linkage to healthcare and support.

CONCLUSION

Our review found evidence that POCT can be implemented successfully in private retail settings in LMICs, but comprehensive protocols are needed. High-quality randomised studies are needed to understand POCTs for infectious diseases other than malaria.

Molecular Farming Strategy for the Rapid Production of Protein-Based Reagents for Use in Infectious Disease Diagnostics

Recombinant proteins are a major breakthrough in biomedical research with a wide range of applications from diagnostics to therapeutics. Strategic construct design, consistent expression platforms, and suitable upstream and downstream techniques are key considerations to produce commercially viable recombinant proteins. The recombinant antigenic protein production for use either as a diagnostic reagent or subunit vaccine formulation is usually carried out in prokaryotic or eukaryotic expression platforms. Microbial and mammalian systems dominate the biopharmaceutical industry for such applications. However, there is no universal expression system that can meet all the requirements for different types of proteins. The adoptability of any expression system is likely based on the quality and quantity of the proteins that can be produced from it. The huge demand of recombinant proteins for different applications requires an inexpensive production platform for rapid development. The molecular farming scientific community has been promoting the plant system for nearly 3 decades as a cost-effective alternative to produce high-quality proteins for research, diagnostic, and therapeutic applications. Here, we discuss how plant biotechnology could offer solutions for the rapid and scalable production of protein antigens as low-cost diagnostic reagents for use in functional assays.

Point-of-care test for tuberculosis: a boon in diagnosis

Rapid diagnosis of tuberculosis (TB) is an effective measure to eradicate this infectious disease worldwide. Traditional methods for screening TB patients do not provide an immediate diagnosis and thus delay treatment. There is an urgent need for the early detection of TB through point-of-care tests (POCTs). Several POCTs are widely available at primary healthcare facilities that assist in TB screening. In addition to the currently used POCTs, advancements in technology have led to the discovery of newer methods that provide accurate and fast information independent of access to laboratory facilities. In the present article, the authors tried to include and describe the potential POCTs for screening TB in patients. Several molecular diagnostic tests, such as nucleic acid amplification tests, including GeneXpert and TB-loop-mediated isothermal amplification, are currently being used as POCTs. Besides these methods, the pathogenic component of Mycobacterium tuberculosis can also be utilized as a biomarker for screening purposes through immunological assays. Similarly, the host immune response to infection has also been utilized as a marker for the diagnosis of TB. These novel biomarkers might include Mtb85, interferon-γ inducible protein-10, volatile organic compounds, acute-phase proteins, etc. Radiological tests have also been observed as POCTs in the TB screening POCT panel. Various POCTs are performed on samples other than sputum, which further eases the screening process. These POCTs should not require large-scale manpower and infrastructure. Hence, POCT should be able to identify patients with M. tuberculosis infection at the primary healthcare level only. There are several other advanced techniques that have been proposed as future POCTs and have been discussed in the present article.

Facilitators and barriers of the implementation of point-of-care devices for cardiometabolic diseases: a scoping review

BACKGROUND

Point-of-care testing (POCT) devices may facilitate the delivery of rapid and timely results, providing a clinically important advantage in patient management. The challenges and constraints in the implementation process, considering different levels of actors have not been much explored. This scoping review aimed to assess literature pertaining to implementation facilitators and barriers of POCT devices for the diagnosis or monitoring of cardiometabolic diseases.

METHODS

A scoping review of the literature was conducted. The inclusion criteria were studies on the inception, planning, or implementation of interventions with POCT devices for the diagnosis or monitoring of cardiometabolic diseases defined as dyslipidemia, cardiovascular diseases, type 2 diabetes, and chronic kidney disease. We searched MEDLINE, Embase, and Global Health databases using the OVID searching engine until May 2022. The Consolidated Framework of Implementation Research (CFIR) was used to classify implementation barriers and facilitators in five constructs. Also, patient, healthcare professional (HCP), and organization level was used.

RESULTS

Twenty studies met the eligibility criteria for data extraction. All studies except two were conducted in high-income countries. Some findings are: 1) Intervention: the most widely recognized facilitator was the quick turnaround time with which results are obtained. 2) Outer setting: at the organizational level, the lack of clear regulatory and accreditation mechanisms has hindered the adoption and sustainability of the use of POCT. 3) Inner setting: for HCP, performing POCT during the consultation was both a facilitator and a barrier in terms of time, personnel, and service delivery. 4) Individuals: the implementation of POCT may generate stress and discomfort in some HCP in terms of training and new responsibilities. 5) Process: for patients, it is highly appreciated that obtaining the sample was simple and more comfortable if venipuncture was not used.

CONCLUSION

This scoping review has described the facilitators and barriers of implementing a POCT device for cardiometabolic conditions using the CFIR. The information can be used to design better strategies to implement these devices and benefit more populations that have low access to cardiometabolic tests.

Low-Cost Electronics for Automatic Classification and Permittivity Estimation of Glycerin Solutions Using a Dielectric Resonator Sensor and Machine Learning Techniques

Glycerin is a versatile organic molecule widely used in the pharmaceutical, food, and cosmetic industries, but it also has a central role in biodiesel refining. This research proposes a dielectric resonator (DR) sensor with a small cavity to classify glycerin solutions. A commercial VNA and a novel low-cost portable electronic reader were tested and compared to evaluate the sensor performance. Within a relative permittivity range of 1 to 78.3, measurements of air and nine distinct glycerin concentrations were taken. Both devices achieved excellent accuracy (98-100%) using Principal Component Analysis (PCA) and Support Vector Machine (SVM). In addition, permittivity estimation using Support Vector Regressor (SVR) achieved low RMSE values, around 0.6 for the VNA dataset and between 1.2 for the electronic reader. These findings prove that low-cost electronics can match the results of commercial instrumentation using machine learning techniques.

A multi-line platinum nanozyme-based lateral flow device for the colorimetric evaluation of total antioxidant capacity in different matrices

The evaluation of Total Antioxidant Capacity (TAC), namely the complete pattern of antioxidant species in a complex medium, is of major interest in many fields ranging from health monitoring to quality control in the food industry. In this framework, point-of-care (POC) testing technologies are a promising diagnostic solution for rapid on-site analyses, unlike laboratory based-assays, which are often limited by centralized analyses, time-consuming and costly procedures, and invasiveness in the case of health diagnostics. In this work, we developed a POC methodology that evaluates TAC in different matrices, exploiting the peroxidase-like properties of 5 nm platinum nanoparticles (PtNPs), combined with a colorimetric paper-based device. Notably, we designed and optimized a multi-line PtNPs-based Lateral Flow Assay (LFA), which relies on three sequential test lines with increasing concentrations of platinum nanozymes, to get a non-invasive, accurate, and fast (10 minutes) colorimetric evaluation of the body TAC in saliva samples. Furthermore, we employed the device as a prototype of a quality control tool in the food industry, for the determination of the TAC in fruit juices.

Development and assessment of a novel gold immunochromatographic assay for the diagnosis of schistosomiasis japonica

Background

The neglected zoonosis, schistosomiasis japonica, remains a major public health problem in the Philippines. The current study aims to develop a novel gold immunochromatographic assay (GICA) and evaluate its performance in the detection of Schistosoma japonicum infection.

Methods

A GICA strip incorporating a S. japonicum saposin protein, SjSAP4 was developed. For each GICA strip test, diluted serum sample (50 µl) was loaded and strips were scanned after 10 min to convert the results into images. ImageJ was used to calculate an R value, which was defined as the signal intensity of the test line divided by the signal intensity of the control line within the cassette. After determination of optimal serum dilution and diluent, the GICA assay was evaluated with sera collected from non-endemic controls (n = 20) and individuals living in schistosomiasis-endemic areas of the Philippines (n = 60), including 40 Kato Katz (KK)-positive participants and 20 subjects confirmed as KK-negative and faecal droplet digital PCR assay (F_ddPCR)-negative at a dilution of 1:20. An ELISA assay evaluating IgG levels against SjSAP4 was also performed on the same panel of sera.

Results

Phosphate-buffered saline (PBS) and 0.9% NaCl were determined as optimal dilution buffer for the GICA assay. The strips tested with serial dilutions of a pooled serum sample from KK-positive individuals (n = 3) suggested that a relatively wide range of dilutions (from 1:10 to 1:320) can be applied for the test. Using the non-endemic donors as controls, the GICA strip showed a sensitivity of 95.0% and absolute specificity; while using the KK-negative and F_ddPCR-negative subjects as controls, the immunochromatographic assay had a sensitivity of 85.0% and a specificity of 80.0%. The SjSAP4-incorperated GICA displayed a high concordance with the SjSAP4-ELISA assay.

Conclusions

The developed GICA assay exhibited a similar diagnostic performance with that of the SjSAP4-ELISA assay, yet the former can be performed by local personnel with minimal training with no requirement for specialised equipment. The GICA assay established here represents a rapid, easy-to-use, accurate and field-friendly diagnostic tool for the on-site surveillance/screening of S. japonicum infection.

Biosensing with Silicon Nitride Microring Resonators Integrated with an On-Chip Filter Bank Spectrometer

Wearable, mobile, and point-of-care (POC) sensors comprise a rapidly expanding field of devices aimed at improving human health by relaying real-time biometric data such as heart rate and glucose levels. The current scope of what these devices can offer healthcare is limited by their inability to measure biomarkers associated with inflammation, well-being, and disease. Photonic biosensors that integrate sensing elements directly with spectrometers, lasers, and detectors are an attractive approach to enabling POC sensors, with distinct advantages in terms of size, weight, power consumption, and cost. Here, we have demonstrated for the first time the integration of photonic microring resonator biosensors with an on-chip microring filter bank spectrometer for the controlled detection of inflammatory biomarker C-reactive protein (CRP) in serum. We demonstrate that sensor and spectrometer performance is tolerant of temperature variation, as temperature dependence moves in parallel. Finally, we assess the impact of manufacturing variability on the 300 mm wafer scale on the performance of the spectrometer. Taken together, these results suggest that integration of on-chip ring filter bank spectrometers with ring resonator-based biosensors constitutes an attractive approach toward cost-effective integrated sensor development.

A scoping review protocol on integration of mobile-linked POC diagnostics in community-based healthcare: User experience

BACKGROUND

Mobile-linked point-of-care diagnostics forms an integral part of diagnostic health services for efficient communication between patients and healthcare professionals despite geographical location and time of diagnosis. The efficiency of this technology lies in the user experience which means that the interaction of the user with the implemented technology needs to be simple, convenient, and consistent. Having a well-structured user experience of these devices in community-based healthcare will aid in sustainable implementation. Herein, we propose to conduct a literature search to systematically map out evidence based on mobile-linked POC diagnostics user experience at a community level in resource-limited settings.

METHODOLOGY

The proposed scoping review will be guided by the advanced Arksey and O'Malley methodological framework and further advanced by Levac et al. A comprehensive search will be conducted to find relevant published literature from the following electronic databases: Scopus, Web of Science, EBSCOhost (Medline, CINAHL, Africa-wide, Academic Search Complete). Grey literature will also be searched, including reports from government and international organizations such as World Health Organization (WHO), Foundation for Innovative New Diagnostics (FIND), and the Food and Drug Administration (FDA). Two independent reviewers will screen the relevant studies and the degree of the agreement will be determined by calculating Cohen's kappa statistic. The quality of eligible data will also be appraised using the mixed method appraisal tool version 2018.

DISCUSSION

We anticipate that the planned scoping review will present useful evidence to inform stakeholders on the integration of mobile-linked diagnostic devices in community-based healthcare which will guide further research on the subject.

A Rapid and Simple Method for Purification of Nucleic Acids on Porous Membranes: Simulation vs. Experiment

Paper-based microfluidic systems have emerged as one of the most promising technologies for developing point-of-care diagnostic platforms (POCT) for detecting and monitoring various diseases. Saliva is a non-invasive biofluid easily collected, transported, and stored. Due to its accessibility and connection to systemic diseases, saliva is one of the best candidates for medical advancement at the point of care, where people can easily monitor their health. However, saliva is a complex mixture of DNA, RNA, proteins, exosomes, and electrolytes. Thus, nucleic acid separation from the salivary components is essential for PCR applications. Paper membranes are a highly porous and foldable structure capable of transporting fluids without pumps and sophisticated systems. The current work presents an insight into simulations for nucleic acid extraction on three types of porous paper membranes for use in point-of-care devices. The flow fluid model is solved on a COMSOL Multiphysics 5.3 free version platform, and the results are compared with experimental assays. The results show that pore uniformity, wet strength, porosity, and functional groups of MF1™ and Fusion 5™ paper membranes are vital parameters affecting nucleic acid extraction and PCR amplification efficiency.

After Theranos: Using point-of-care testing to advance measures of health biomarkers in human biology research

OBJECTIVES

The rise and fall of the health technology startup Theranos is emblematic of the promise and peril of point-of-care testing (POCT). Instruments that deliver immediate results from minimally invasive samples at the location of collection can provide powerful tools to deliver health data in clinical and public health contexts. Yet, POCT availability is driven largely by market interests, which limits the development of inexpensive tests for diverse health conditions that can be used in resource-limited settings. These constraints, combined with complex regulatory hurdles and substantial ethical challenges, have contributed to the underutilization of POCT in human biology research.

METHODS

We evaluate current POCT capabilities and limitations, discuss promising applications for POCT devices in resource-limited settings, and discuss the future of POCT.

RESULTS

As evidenced by publication trends, POCT platforms have rapidly advanced in recent years, gaining traction among clinicians and health researchers. We highlight POCT devices of potential interest to population-based researchers and present specific examples of POCT applications in human biology research.

CONCLUSIONS

Several barriers can limit POCT applications, including cost, lack of regulatory approval for non-clinical use, requirements for expensive equipment, and the dearth of validation in remote field conditions. Despite these issues, we see immense potential for emerging POCT technology capable of analyzing new sample types and used in conjunction with increasingly common technology (e.g., smart phones). We argue that the fallout from Theranos may ultimately provide an opportunity to advance POCT, leading to more ethical data collection and novel opportunities in human biology research.

Bringing the lab bench to the field: Point-of-care testing for enhancing health research and stakeholder engagement in rural/remote, indigenous, and resource-limited contexts

Point-of-care testing (POCT) allows researchers and health-care providers to bring the lab bench to the field, providing essential health information that can be leveraged to improve health care, accessibility, and understanding across clinical and research settings. Gaps in health service access are most pronounced in what we term RIR settings-rural/remote regions, involving Indigenous peoples, and/or within resource-limited settings. In these contexts, morbidity and mortality from infectious and non-communicable diseases are disproportionately higher due to numerous geographic, economic, political, and sociohistorical factors. Human biologists and global health scholars are well-positioned to contribute on-the-ground-level insights that can serve to minimize global health inequities and POCT has the potential to augment such approaches. While the clinical benefits of POCT include increasing health service access by bringing testing, rapid diagnosis, and treatment to underserved communities with limited pathways to centralized laboratory testing, POCT also provides added benefits to both health-focused researchers and their participants. Through portable, minimally invasive devices, researchers can provide actionable health data to participants by coupling POCT with population-specific health education, discussing results and their implications, creating space for participants to voice concerns, and facilitating linkages to treatment. POCT can also strengthen human biology research by shedding light on questions of evolutionary and biocultural importance. Here, we expand on the epidemiological and research value, as well as practical and ethical challenges of POCT across stakeholders (i.e., participant, community, health researcher, and trainee). Finally, we emphasize the immense opportunities of POCT for fostering collaborative research and enhancing access to health delivery and information and, by extension, helping to mitigate persistent global health inequities.

Direct Processing and Storage of Cell-Free Plasma Using Dried Plasma Spot Cards

Plasma separation cards represent a viable approach for expanding testing capabilities away from clinical settings by generating cell-free plasma with minimal user intervention. These devices typically comprise a basic structure of the plasma separation membrane, unconstrained porous collection pad, and utilize either (i) lateral or (ii) vertical fluidic pathways for separating plasma. Unfortunately, these configurations are highly susceptible to (i) inconsistent sampling volume due to differences in the patient hematocrit or (ii) severe contamination due to leakage of red blood cells or release of hemoglobin (i.e., hemolysis). Herein, we combine the enhanced sampling of our previously reported patterned dried blood spot cards with an assembly of porous separation materials to produce a patterned dried plasma spot card for direct processing and storage of cell-free plasma. Linking both vertical separation and lateral distribution of plasma yields discrete plasma collection zones that are spatially protected from potential contamination due to hemolysis and an inlet zone enriched with blood cells for additional testing. We evaluate the versatility of this card by quantitation of three classes of analytes and techniques including (i) the soluble transferrin receptor by enzyme-linked immunosorbent assay, (ii) potassium by inductively coupled plasma atomic emission spectroscopy, and (iii) 18S rRNA by reverse transcriptase quantitative polymerase chain reaction. We achieve quantitative recovery of each class of analyte with no statistically significant difference between dried and liquid reference samples. We anticipate that this sampling approach can be applied broadly to improve access to critical blood testing in resource-limited settings or at the point-of-care.

Translating diagnostics and drug delivery technologies to low-resource settings

Diagnostics and drug delivery technologies engineered for low-resource settings aim to meet their technical design specifications using strategies that are compatible with limited equipment, infrastructure, and operator training. Despite many preclinical successes, very few of these devices have been translated to the clinic. Here, we identify factors that contribute to the clinical success of diagnostics and drug delivery systems for low-resource settings, including the need to engage key stakeholders at an early stage, and provide recommendations for the clinical translation of future medical technologies.

Automated Recognition of Plasmodium falciparum Parasites from Portable Blood Levitation Imaging

In many malaria-endemic regions, current detection tools are inadequate in diagnostic accuracy and accessibility. To meet the need for direct, phenotypic, and automated malaria parasite detection in field settings, a portable platform to process, image, and analyze whole blood to detect Plasmodium falciparum parasites, is developed. The liberated parasites from lysed red blood cells suspended in a magnetic field are accurately detected using this cellphone-interfaced, battery-operated imaging platform. A validation study is conducted at Ugandan clinics, processing 45 malaria-negative and 36 malaria-positive clinical samples without external infrastructure. Texture and morphology features are extracted from the sample images, and a random forest classifier is trained to assess infection status, achieving 100% sensitivity and 91% specificity against gold-standard measurements (microscopy and polymerase chain reaction), and limit of detection of 31 parasites per µL. This rapid and user-friendly platform enables portable parasite detection and can support malaria diagnostics, surveillance, and research in resource-constrained environments.

Magnetic Bead Handling Using a Paper-Based Device for Quantitative Point-of-Care Testing

Microfluidic paper-based analytical devices (μPADs) have been extensively proposed as ideal tools for point-of-care (POC) testing with minimal user training and technical requirements. However, most μPADs use dried bioreagents, which complicate production, reduce device reproducibility and stability, and require transport and storage under temperature and humidity-controlled conditions. In this work, we propose a μPAD produced using an affordable craft-cutter and stored at room temperature, which is used to partially automate a single-step colorimetric magneto-immunoassay. As a proof-of-concept, the μPAD has been applied to the quantitative detection of Plasmodium falciparum lactate dehydrogenase (Pf-LDH), a biomarker of malaria infection. In this system, detection is based on a single-step magneto-immunoassay that consists of a single 5-min incubation of the lysed blood sample with immuno-modified magnetic beads (MB), detection antibody, and an enzymatic signal amplifier (Poly-HRP). This mixture is then transferred to a single-piece paper device where, after on-chip MB magnetic concentration and washing, signal generation is achieved by adding a chromogenic enzyme substrate. The colorimetric readout is achieved by the naked eye or using a smartphone camera and free software for image analysis. This μPAD afforded quantitative Pf-LDH detection in <15 min, with a detection limit of 6.25 ng mL−1 when the result was interpreted by the naked eye and 1.4 ng mL−1 when analysed using the smartphone imaging system. Moreover, the study of a battery of clinical samples revealed concentrations of Pf-LDH that correlated with those provided by the reference ELISA and with better sensitivity than a commercial rapid diagnostic test (RDT). These results demonstrate that magneto-immunoassays can be partly automated by employing a μPAD, achieving a level of handling that approaches the requirements of POC testing.

Asymmetric Mach–Zehnder Interferometric Biosensing for Quantitative and Sensitive Multiplex Detection of Anti-SARS-CoV-2 Antibodies in Human Plasma

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic has once more emphasized the urgent need for accurate and fast point-of-care (POC) diagnostics for outbreak control and prevention. The main challenge in the development of POC in vitro diagnostics (IVD) is to combine a short time to result with a high sensitivity, and to keep the testing cost-effective. In this respect, sensors based on photonic integrated circuits (PICs) may offer advantages as they have features such as a high analytical sensitivity, capability for multiplexing, ease of miniaturization, and the potential for high-volume manufacturing. One special type of PIC sensor is the asymmetric Mach–Zehnder Interferometer (aMZI), which is characterized by a high and tunable analytical sensitivity. The current work describes the application of an aMZI-based biosensor platform for sensitive and multiplex detection of anti-SARS-CoV-2 antibodies in human plasma samples using the spike protein (SP), the receptor-binding domain (RBD), and the nucleocapsid protein (NP) as target antigens. The results are in good agreement with several CE-IVD marked reference methods and demonstrate the potential of the aMZI biosensor technology for further development into a photonic IVD platform.

Rapid Quantum Magnetic IL-6 Point-of-Care Assay in Patients Hospitalized with COVID-19

Interleukin-6 (IL-6) has been linked to several life-threatening disease processes. Developing a point-of-care testing platform for the immediate and accurate detection of IL-6 concentrations could present a valuable tool for improving clinical management in patients with IL-6-mediated diseases. Drawing on an available biobank of samples from 35 patients hospitalized with COVID-19, a novel quantum-magnetic sensing platform is used to determine plasma IL-6 concentrations. A strong correlation was observed between IL-6 levels measured by QDTI10x and the Luminex assay (r = 0.70, p-value < 0.001) and between QDTI80x and Luminex (r = 0.82, p-value < 0.001). To validate the non-inferiority of QDTI to Luminex in terms of the accuracy of IL-6 measurement, two clinical parameters—the need for intensive care unit admission and the need for mechanical intubation—were chosen. IL-6 concentrations measured by the two assays were compared with respect to these clinical outcomes. Results demonstrated a comparative predictive performance between the two assays with a significant correlation coefficient. Conclusion: In short, the QDTI assay holds promise for implementation as a potential tool for rapid clinical decision in patients with IL-6-mediated diseases. It could also reduce healthcare costs and enable the development of future various biomolecule point-of-care tests for different clinical scenarios.

Giant Magnetoresistance Biosensors in Biomedical Applications

The giant magnetoresistance (GMR) effect has seen flourishing development from theory to application in the last three decades since its discovery in 1988. Nowadays, commercial devices based on the GMR effect, such as hard-disk drives, biosensors, magnetic field sensors, microelectromechanical systems (MEMS), etc., are available in the market, by virtue of the advances in state-of-the-art thin-film deposition and micro- and nanofabrication techniques. Different types of GMR biosensor arrays with superior sensitivity and robustness are available at a lower cost for a wide variety of biomedical applications. In this paper, we review the recent advances in GMR-based biomedical applications including disease diagnosis, genotyping, food and drug regulation, brain and cardiac mapping, etc. The GMR magnetic multilayer structure, spin valve, and magnetic granular structure, as well as fundamental theories of the GMR effect, are introduced at first. The emerging topic of flexible GMR for wearable biosensing is also included. Different GMR pattern designs, sensor surface functionalization, bioassay strategies, and on-chip accessories for improved GMR performances are reviewed. It is foreseen that combined with the state-of-the-art complementary metal-oxide-semiconductor (CMOS) electronics, GMR biosensors hold great promise in biomedicine, particularly for point-of-care (POC) disease diagnosis and wearable devices for real-time health monitoring.

Bridging the gap between development of point-of-care nucleic acid testing and patient care for sexually transmitted infections

The incidence rates of sexually transmitted infections (STIs), including the four major curable STIs - chlamydia, gonorrhea, trichomoniasis and, syphilis - continue to increase globally, causing medical cost burden and morbidity especially in low and middle-income countries (LMIC). There have seen significant advances in diagnostic testing, but commercial antigen-based point-of-care tests (POCTs) are often insufficiently sensitive and specific, while near-point-of-care (POC) instruments that can perform sensitive and specific nucleic acid amplification tests (NAATs) are technically complex and expensive, especially for LMIC. Thus, there remains a critical need for NAAT-based STI POCTs that can improve diagnosis and curb the ongoing epidemic. Unfortunately, the development of such POCTs has been challenging due to the gap between researchers developing new technologies and healthcare providers using these technologies. This review aims to bridge this gap. We first present a short introduction of the four major STIs, followed by a discussion on the current landscape of commercial near-POC instruments for the detection of these STIs. We present relevant research toward addressing the gaps in developing NAAT-based STI POCT technologies and supplement this discussion with technologies for HIV and other infectious diseases, which may be adapted for STIs. Additionally, as case studies, we highlight the developmental trajectory of two different POCT technologies, including one approved by the United States Food and Drug Administration (FDA). Finally, we offer our perspectives on future development of NAAT-based STI POCT technologies.

Critical Factors and Economic Methods for Regulatory Impact Assessment in the Medical Device Industry

Introduction

Methods

Results

Discussion

A sample-to-answer electrochemical biosensor system for biomarker detection

Biomarker detection is critical for the diagnosis and treatment of numerous diseases. Typically, target biomarkers in blood samples are measured through tests conducted at centralized laboratories. Testing at central laboratories increases wait times for results, in turn increasing healthcare costs and negatively impacting patient outcomes. Alternatively, point-of-care platforms enable the rapid measurement of biomarkers, expand testing location capabilities and mitigate manual processing steps through integration and automation. However, many of these systems focus on sample detection rather than the equally important sample preparation. Here we present a fully integrated and automated sample-to-answer electrochemical biosensing platform which incorporates each aspect of the biomarker testing workflow from blood collection to sample preparation to assay operation and readout. The system combines a commercial microneedle blood sampling device with membrane-based plasma filtration upstream of a bead-based electrochemical immunoassay. We characterize the high separation efficiency (>99%) and low non-specific binding of the whole blood-to-plasma filtration membrane under a range of operating conditions. We demonstrate a full sample-to-answer workflow through the analysis of interlukin-6-spiked blood samples.

A Strategy to Detect Emerging Non-Delta SARS-CoV-2 Variants with a Monoclonal Antibody Specific for the N501 Spike Residue

Efforts to control SARS-CoV-2 have been challenged by the emergence of variant strains that have important implications for clinical and epidemiological decision making. Four variants of concern (VOCs) have been designated by the Centers for Disease Control and Prevention (CDC), namely, B.1.617.2 (delta), B.1.1.7 (alpha), B.1.351 (beta), and P.1 (gamma), although the last three have been downgraded to variants being monitored (VBMs). VOCs and VBMs have shown increased transmissibility and/or disease severity, resistance to convalescent SARS-CoV-2 immunity and antibody therapeutics, and the potential to evade diagnostic detection. Methods are needed for point-of-care (POC) testing to rapidly identify these variants, protect vulnerable populations, and improve surveillance. Antigen-detection rapid diagnostic tests (Ag-RDTs) are ideal for POC use, but Ag-RDTs that recognize specific variants have not yet been implemented. Here, we describe a mAb (2E8) that is specific for the SARS-CoV-2 spike protein N501 residue. The 2E8 mAb can distinguish the delta VOC from variants with the N501Y meta-signature, which is characterized by convergent mutations that contribute to increased virulence and evasion of host immunity. Among the N501Y-containing mutants formerly designated as VOCs (alpha, beta, and gamma), a previously described mAb, CB6, can distinguish beta from alpha and gamma. When used in a sandwich ELISA, these mAbs sort these important SARS-CoV-2 variants into three diagnostic categories, namely, (1) delta, (2) alpha or gamma, and (3) beta. As delta is currently the predominant variant globally, they will be useful for POC testing to identify N501Y meta-signature variants, protect individuals in high-risk settings, and help detect epidemiological shifts among SARS-CoV-2 variants.

Topographical Vacuum Sealing of 3D-Printed Multiplanar Microfluidic Structures

We demonstrate a novel way of creating three-dimensional microfluidic channels capable of following complex topographies. To this end, substrates with open channels and different geometries were 3D-printed, and the open channels were consecutively closed with a thermoplastic using a low-resolution vacuum-forming approach. This process allows the sealing of channels that are located on the surface of complex multiplanar topographies, as the thermoplastic aligns with the surface-shape (the macrostructure) of the substrate, while the microchannels remain mostly free of thermoplastic as their small channel size resists thermoplastic inflow. This new process was analyzed for its capability to consistently close different substrate geometries, which showed reliable sealing of angles >90°. Furthermore, the thermoplastic intrusion into channels of different widths was quantified, showing a linear effect of channel width and percentage of thermoplastic intrusion; ranging from 43.76% for large channels with 2 mm width to only 5.33% for channels with 500 µm channel width. The challenging sealing of substrate ‘valleys’, which are created when two large protrusions are adjacent to each other, was investigated and the correlation between protrusion distance and height is shown. Lastly, we present three application examples: a serpentine mixer with channels spun around a cuboid, increasing the usable surface area; a cuvette-inspired flow cell for a 2-MXP biosensor based on molecular imprinted polymers, fitting inside a standard UV/Vis-Spectrophotometer; and an adapter system that can be manufactured by one-sided injection molding and is self-sealed before usage. These examples demonstrate how this novel technology can be used to easily adapt microfluidic circuits for application in biosensor platforms.

Next-Generation Continuous Metabolite Sensing toward Emerging Sensor Needs

This article discusses the emergent biosensor technology focused on continuous biosensing of metabolites by non-invasive sampling of body fluids emphasized on physiological monitoring in mobility-constrained populations, resource-challenged settings, and harsh environments. The boom of innovative ideas and endless opportunities in healthcare technologies has transformed traditional medicine into a sustainable link between medical practitioners and patients to provide solutions for faster disease diagnosis. The future of healthcare is focused on empowering users to manage their own health. The confluence of big data and predictive analysis and the internet of things (IoT) technology have shown the potential of converting the abundant health profile data amassed from medical diagnosis of patients into useable information, whilst allowing caregivers to provide suitable treatment plans. The implementation of the IoT technology has opened up advanced approaches in real-time, continuous, remote monitoring of patients. Wearable, point-of-care biosensors are the future roadmap to providing direct, real-time information of health status to the user and medical professionals in this digitized era.

Lateral Flow Serodiagnosis in the Double-Antigen Sandwich Format: Theoretical Consideration and Confirmation of Advantages

Determination of the presence in the blood of antibodies specific to the causative agent of a particular disease (serodiagnosis) is an effective approach in medical analytical chemistry. Serodiagnostics performed in the lateral flow immunoassay format (immunochromatography) meet the modern requirements for point-of-care testing and are supported by existing technologies of large-scale diagnostic tests production, thus increasing the amount of attention in a tense epidemiological situation. For traditional lateral flow serodiagnostics formats, a large number of nonspecific immunoglobulins in the sample significantly reduces the degree of detectable binding. To overcome these limitations, an assay based on the formation of immobilized antigen-specific antibody-labeled antigen complexes detection was proposed. However, the requirements for its implementation, providing maximum sensitivity, have not been established. This article describes the mathematical model for the above assay. The influence of the ratio of reagent concentrations on the analysis results is considered. It is noted that the formation of specific antibody complexes with several labeled antigens is the main limiting factor in reducing the detection limit, and methods are proposed to minimize this factor. Recommendations for the choice of the assay conditions, following from the analysis of the model, are confirmed experimentally.