A fully integrated paperfluidic molecular diagnostic chip for the extraction, amplification, and detection of nucleic acids from clinical samples

Whole blood gene expression within days after total-body irradiation predicts long term survival in Gottingen minipigs

Gottingen minipigs mirror the physiological radiation response observed in humans and hence make an ideal candidate model for studying radiation biodosimetry for both limited-sized and mass casualty incidents. We examined the whole blood gene expression profiles starting one day after total-body irradiation with increasing doses of gamma-rays. The minipigs were monitored for up to 45 days or time to euthanasia necessitated by radiation effects. We successfully identified dose- and time-agnostic (over a 1-7 day period after radiation), survival-predictive gene expression signatures derived using machine-learning algorithms with high sensitivity and specificity. These survival-predictive signatures fare better than an optimally performing dose-differentiating signature or blood cellular profiles. These findings suggest that prediction of survival is a much more useful parameter for making triage, resource-utilization and treatment decisions in a resource-constrained environment compared to predictions of total dose received. It should hopefully be possible to build such classifiers for humans in the future.

Recent innovations in cost-effective polymer and paper hybrid microfluidic devices

Hybrid microfluidic systems that are composed of multiple different types of substrates have been recognized as a versatile and superior platform, which can draw benefits from different substrates while avoiding their limitations. This review article introduces the recent innovations of different types of low-cost hybrid microfluidic devices, particularly focusing on cost-effective polymer- and paper-based hybrid microfluidic devices. In this article, the fabrication of these hybrid microfluidic devices is briefly described and summarized. We then highlight various hybrid microfluidic systems, including polydimethylsiloxane (PDMS)-based, thermoplastic-based, paper/polymer hybrid systems, as well as other emerging hybrid systems (such as thread-based). The special benefits of using these hybrid systems have been summarized accordingly. A broad range of biological and biomedical applications using these hybrid microfluidic devices are discussed in detail, including nucleic acid analysis, protein analysis, cellular analysis, 3D cell culture, organ-on-a-chip, and tissue engineering. The perspective trends of hybrid microfluidic systems involving the improvement of fabrication techniques and broader applications are also discussed at the end of the review.

PARP1: A Potential Molecular Marker to Identify Cancer During Colposcopy Procedures

Despite efforts in prevention, cervical cancer still presents with a high worldwide incidence and remains a great problem in public health, especially in low-income countries. Screening programs, such as colposcopy with Papanicolaou testing, have greatly improved mortality rates. However, the agents currently used to delineate those lesions (topical application of acetic acid or Lugol iodine) lack specificity and sometimes can lead to unnecessary biopsies or even cervical excisions. A tool to enable in vivo histology to quickly and quantitatively distinguish between tumor, dysplastic tissue, and healthy tissue would be of great clinical interest. Methods: Here, we describe the use of PARPi-FL, a fluorescent inhibitor of poly[adenosine diphosphate-ribose]polymerase 1 (PARP1), which is a nuclear enzyme that is overexpressed in cancer when compared with the normal surrounding tissues. We exploit its use as an optical imaging agent to specifically target PARP1 expression, which was demonstrated to be higher in cervical cancer than the normal surrounding tissue. Results: After topical application of PARPi-FL on freshly excised cone biopsy samples, the nuclei of tumor cells emitted a specific fluorescent signal that could be visualized using a handheld fluorescence confocal microscope. Conclusion: This approach has the potential to improve in vivo identification of tumor cells during colposcopy examination, allowing a rapid, noninvasive, and accurate histopathologic assessment.

Emerging point-of-care biosensors for rapid diagnosis of COVID-19: current progress, challenges, and future prospects

Coronavirus disease 2019 (COVID-19) pandemic is currently a serious global health threat. While conventional laboratory tests such as quantitative real-time polymerase chain reaction (qPCR), serology tests, and chest computerized tomography (CT) scan allow diagnosis of COVID-19, these tests are time-consuming and laborious, and are limited in resource-limited settings or developing countries. Point-of-care (POC) biosensors such as chip-based and paper-based biosensors are typically rapid, portable, cost-effective, and user-friendly, which can be used for COVID-19 in remote settings. The escalating demand for rapid diagnosis of COVID-19 presents a strong need for a timely and comprehensive review on the POC biosensors for COVID-19 that meet ASSURED criteria: Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Deliverable to end users. In the present review, we discuss the importance of rapid and early diagnosis of COVID-19 and pathogenesis of COVID-19 along with the key diagnostic biomarkers. We critically review the most recent advances in POC biosensors which show great promise for the detection of COVID-19 based on three main categories: chip-based biosensors, paper-based biosensors, and other biosensors. We subsequently discuss the key benefits of these biosensors and their use for the detection of antigen, antibody, and viral nucleic acids. The commercial POC biosensors for COVID-19 are critically compared. Finally, we discuss the key challenges and future perspectives of developing emerging POC biosensors for COVID-19. This review would be very useful for guiding strategies for developing and commercializing rapid POC tests to manage the spread of infections.Graphical abstract.

Electrochemical Strategy for Low-Cost Viral Detection

Sexually transmitted infections, including the human immunodeficiency virus (HIV) and the human papillomavirus (HPV), disproportionally impact those in low-resource settings. Early diagnosis is essential for managing HIV. Similarly, HPV causes nearly all cases of cervical cancer, the majority (90%) of which occur in low-resource settings. Importantly, infection with HPV is six times more likely to progress to cervical cancer in women who are HIV-positive. An inexpensive, adaptable point-of-care test for viral infections would make screening for these viruses more accessible to a broader set of the population. Here, we report a novel, cost-effective electrochemical platform using gold leaf electrodes to detect clinically relevant viral loads. We have combined this platform with loop-mediated isothermal amplification and a CRISPR-based recognition assay to detect HPV. Lower limits of detection were demonstrated down to 10⁴ total copies of input nucleic acids, which is a clinically relevant viral load for HPV DNA. Further, proof-of-concept experiments with cervical swab samples, extracted using standard extraction protocols, demonstrated that the strategy is extendable to complex human samples. This adaptable technology could be applied to detect any viral infection rapidly and cost-effectively.

A HiPAD Integrated with rGO/MWCNTs Nano-Circuit Heater for Visual Point-of-Care Testing of SARS-CoV-2

Nowadays, the main obstacle for further miniaturization and integration of nucleic acids point-of-care testing devices is the lack of low-cost and high-performance heating materials for supporting reliable nucleic acids amplification. Herein, reduced graphene oxide hybridized multi-walled carbon nanotubes nano-circuit integrated into an ingenious paper-based heater is developed, which is integrated into a paper-based analytical device (named HiPAD). The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still raging across the world. As a proof of concept, the HiPAD is utilized to visually detect the SARS-CoV-2 N gene using colored loop-mediated isothermal amplification reaction. This HiPAD costing a few dollars has comparable detection performance to traditional nucleic acids amplifier costing thousands of dollars. The detection range is from 25 to 2.5 × 1010 copies mL-1 in 45 min. The detection limit of 25 copies mL-1 is 40 times more sensitive than 1000 copies mL-1 in conventional real-time PCR instruments. The disposable paper-based chip could also avoid potential secondary transmission of COVID-19 by convenient incineration to guarantee biosafety. The HiPAD or easily expanded M-HiPAD (for multiplex detection) has great potential for pathogen diagnostics in resource-limited settings.

Nucleic acid lateral flow assay for simultaneous detection of hygiene indicator bacteria

A simple and rapid polymerase chain reaction (PCR)-based lateral flow assay (LFA) was developed for multiplex detection of hygiene indicator bacteria. Specifically, new PCR primers were designed for accurately detecting Escherichia coli, coliform bacteria, and total bacteria, and the results obtained as a colorimetric signal (generated by the accumulation of gold nanoparticles at distinct test zones on flow strips) could be identified by the naked eye in <10 min after the completion of PCR. The proposed LFA system did not exhibit any cross-reactivities with 8 distinct bacterial strains and can detect down to 1 colony forming unit (CFU)/mL. Furthermore, three species of cultured bacteria (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) inoculated onto sterilized ham were successfully analyzed using the LFA system, which demonstrated that this system shows sufficient sensitivity and specificity for food hygiene monitoring. The speed and simplicity of this LFA make it suitable for use in the food industry as part of routine screening analysis.

Heat-enhancing aggregation of gold nanoparticles combined with loop-mediated isothermal amplification (HAG-LAMP) for Plasmodium falciparum detection

Malaria infection represents a major public health and economic issue that leads to morbidity and mortality globally. A highly effective and uncomplicated detection tool is required for malaria control in geographical hotspots of transmission. We developed a simple and more sensitive novel approach for the detection of the 18S rRNA gene of Plasmodium falciparum based on loop-mediated isothermal amplification (LAMP) and visualization using colorimetric, streptavidin-functionalized gold nanoparticles (SA-GNPs). Two loop primers of LAMP were biotinylated to produce biotin-containing products during amplification. After the addition of SA-GNPs, clusters of avidin-biotin complexes were established in the LAMP structure. While the positive reactions remained wine red, the negative reactions became colorless with partial aggregations induced by hydrochloric acid (HCl) under heat enhancement (60 °C). All steps of the assay were completed within 50 min, its detection limit was 1 parasite/μL, and it was highly specific for P. falciparum. This effortless detection system with high sensitivity and specificity could provide an alternative choice for malaria diagnostics in resource-limited regions.

Long-term dry storage of enzyme-based reagents for isothermal nucleic acid amplification in a porous matrix for use in point-of-care diagnostic devices

Nucleic acid amplification test (NAAT)-based point-of-care (POC) devices are rapidly growing for use in low-resource settings. However, key challenges are the ability to store the enzyme-based reagents in dry form in the device and the long-term stability of those reagents at elevated temperatures, especially where ambient temperatures could be as high as 45 °C. Here, we describe a set of excipients including a combination of trehalose, polyethylene glycol and dextran, and a method for using them that allows long-term dry storage of enzyme-based reagents for an isothermal strand displacement amplification (iSDA) reaction in a porous matrix. Various porous materials, including nitrocellulose, cellulose, and glass fiber, were tested. Co-dried reagents for iSDA always included those that amplified the ldh1 gene in Staphylococcus aureus (a polymerase and a nicking enzyme, 4 primers, dNTPs and a buffer). Reagents also either included a capture probe and a streptavidin-Au label required for lateral flow (LF) detection after amplification, or a fluorescent probe used for real-time detection. The reagents showed the best stability in a glass fiber matrix when stored in the presence of 10% trehalose and 2.5% dextran. The reagents were stable for over a year at ∼22 °C as determined by lateral flow detection and gel electrophoresis. The reagents also exhibited excellent stability after 360 h at 45 °C; the assay still detected as few as 10 copies of ldh1 gene target by lateral flow detection, and 50 copies with real-time fluorescence detection. These results demonstrate the potential for incorporation of amplification reagents in dry form in point-of-care devices for use in a wide range of settings.

Nucleic acid analysis on paper substrates (NAAPs): an innovative tool for Point of Care (POC) infectious disease diagnosis

The cost-effective rapid diagnosis of infectious diseases is an essential and important factor for curing such diseases in the global public health care picture. Owing to poor infrastructure and lack of sanitation, these diseases have an extreme impact on remote and rural areas, especially in developing countries, and there are unresolved challenges. Molecular diagnosis, such as nucleic acid analysis, plays a key role in the significant treatment of numerous infectious diseases. Current molecular diagnostic assays require a sophisticated laboratory setup with expensive components. Molecular diagnosis on a microfluidic point-of-care (POC) platform is attractive to researchers for disease detection with proper prevention. Compared to various microfluidic substrate materials, paper-based POC technologies offer significant cost-effective solutions over high-cost clinical instruments to fill the gap between the needs of users and affordability. Low-cost paper-based microfluidic POC technologies provide portable and disposable diagnostic systems for multiple disease detection that may be extremely useful in remote areas. This article presents a critical review of paper-based microfluidic device technology which has become an imminent platform to adjust the current health scenario for the detection of diseases using different stages of nucleic acid analysis, such as extraction, amplification and detection of nucleic acid, with future perspectives for paper substrates.

COVID-19 Diagnostic Strategies. Part I: Nucleic Acid-Based Technologies

The novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused respiratory infection, resulting in more than two million deaths globally and hospitalizing thousands of people by March 2021. A considerable percentage of the SARS-CoV-2 positive patients are asymptomatic or pre-symptomatic carriers, facilitating the viral spread in the community by their social activities. Hence, it is critical to have access to commercialized diagnostic tests to detect the infection in the earliest stages, monitor the disease, and follow up the patients. Various technologies have been proposed to develop more promising assays and move toward the mass production of fast, reliable, cost-effective, and portable PoC diagnostic tests for COVID-19 detection. Not only COVID-19 but also many other pathogens will be able to spread and attach to human bodies in the future. These technologies enable the fast identification of high-risk individuals during future hazards to support the public in such outbreaks. This paper provides a comprehensive review of current technologies, the progress in the development of molecular diagnostic tests, and the potential strategies to facilitate innovative developments in unprecedented pandemics.

Rapid Detection of Pathogens in Wound Exudate via Nucleic Acid Lateral Flow Immunoassay

The rapid detection of pathogens in infected wounds can significantly improve the clinical outcome. Wound exudate, which can be collected in a non-invasive way, offers an attractive sample material for the detection of pathogens at the point-of-care (POC). Here, we report the development of a nucleic acid lateral flow immunoassay for direct detection of isothermally amplified DNA combined with fast sample preparation. The streamlined protocol was evaluated using human wound exudate spiked with the opportunistic pathogen Pseudomonas aeruginosa that cause severe health issues upon wound colonization. A detection limit of 2.1 × 10⁵ CFU per mL of wound fluid was achieved, and no cross-reaction with other pathogens was observed. Furthermore, we integrated an internal amplification control that excludes false negative results and, in combination with the flow control, ensures the validity of the test result. The paper-based approach with only three simple hands-on steps has a turn-around time of less than 30 min and covers the complete analytical process chain from sample to answer. This newly developed workflow for wound fluid diagnostics has tremendous potential for reliable pathogen POC testing and subsequent target-oriented therapy.

Addressing cervical cancer screening disparities through advances in artificial intelligence and nanotechnologies for cellular profiling

Almost all cases of cervical cancer are caused by the human papilloma virus (HPV). Detection of pre-cancerous cervical changes provides a window of opportunity for cure of an otherwise lethal disease when metastatic. With a greater understanding of the biology and natural course of high-risk HPV infections, screening methods have shifted beyond subjective Pap smears toward more sophisticated and objective tactics. This has led to a substantial growth in the breadth and depth of HPV-based cervical cancer screening tests, especially in developed countries without constrained resources. Many low- and middle-income countries (LMICs) have less access to advanced laboratories and healthcare resources, so new point-of-care (POC) technologies have been developed to provide test results in real time, improve the efficiency of techniques, and increase screening adoption. In this Review, we will discuss how novel decentralized screening technologies and computational strategies improve upon traditional methods and how their realized promise could further democratize cervical cancer screening and promote greater disease prevention.

Multiplex Molecular Point-of-Care Test for Syndromic Infectious Diseases

Point-of-care (POC) molecular diagnostics for clinical microbiology and virology has primarily focused on the detection of a single pathogen. More recently, it has transitioned into a comprehensive syndromic approach that employs multiplex capabilities, including the simultaneous detection of two or more pathogens. Multiplex POC tests provide higher accuracy to for actionable decisionmaking in critical care, which leads to pathogen-specific treatment and standardized usages of antibiotics that help prevent unnecessary processes. In addition, these tests can be simple enough to operate at the primary care level and in remote settings where there is no laboratory infrastructure. This review focuses on state-of-the-art multiplexed molecular point-of-care tests (POCT) for infectious diseases and efforts to overcome their limitations, especially related to inadequate throughput for the identification of syndromic diseases. We also discuss promising and imperative clinical POC approaches, as well as the possible hurdles of their practical applications as front-line diagnostic tests.

Developments in integrating nucleic acid isothermal amplification and detection systems for point-of-care diagnostics

Early disease detection through point-of-care (POC) testing is vital for quickly treating patients and preventing the spread of harmful pathogens. Disease diagnosis is generally accomplished using quantitative polymerase chain reaction (qPCR) to amplify nucleic acids in patient samples, permitting detection even at low target concentrations. However, qPCR requires expensive equipment, trained personnel, and significant time. These resources are not available in POC settings, driving researchers to instead utilize isothermal amplification, conducted at a single temperature, as an alternative. Common isothermal amplification methods include loop-mediated isothermal amplification, recombinase polymerase amplification, rolling circle amplification, nucleic acid sequence-based amplification, and helicase-dependent amplification. There has been a growing interest in combining such amplification methods with POC detection methods to enable the development of diagnostic tests that are well suited for resource-limited settings as well as developed countries performing mass screenings. Exciting developments have been made in the integration of these two research areas due to the significant impact that such approaches can have on healthcare. This review will primarily focus on advances made by North American research groups between 2015 and June 2020, and will emphasize integrated approaches that reduce user steps, reliance on expensive equipment, and the system's time-to-result.

Advances in point-of-care nucleic acid extraction technologies for rapid diagnosis of human and plant diseases

Global health and food security constantly face the challenge of emerging human and plant diseases caused by bacteria, viruses, fungi, and other pathogens. Disease outbreaks such as SARS, MERS, Swine Flu, Ebola, and COVID-19 (on-going) have caused suffering, death, and economic losses worldwide. To prevent the spread of disease and protect human populations, rapid point-of-care (POC) molecular diagnosis of human and plant diseases play an increasingly crucial role. Nucleic acid-based molecular diagnosis reveals valuable information at the genomic level about the identity of the disease-causing pathogens and their pathogenesis, which help researchers, healthcare professionals, and patients to detect the presence of pathogens, track the spread of disease, and guide treatment more efficiently. A typical nucleic acid-based diagnostic test consists of three major steps: nucleic acid extraction, amplification, and amplicon detection. Among these steps, nucleic acid extraction is the first step of sample preparation, which remains one of the main challenges when converting laboratory molecular assays into POC tests. Sample preparation from human and plant specimens is a time-consuming and multi-step process, which requires well-equipped laboratories and skilled lab personnel. To perform rapid molecular diagnosis in resource-limited settings, simpler and instrument-free nucleic acid extraction techniques are required to improve the speed of field detection with minimal human intervention. This review summarizes the recent advances in POC nucleic acid extraction technologies. In particular, this review focuses on novel devices or methods that have demonstrated applicability and robustness for the isolation of high-quality nucleic acid from complex raw samples, such as human blood, saliva, sputum, nasal swabs, urine, and plant tissues. The integration of these rapid nucleic acid preparation methods with miniaturized assay and sensor technologies would pave the road for the "sample-in-result-out" diagnosis of human and plant diseases, especially in remote or resource-limited settings.

Integrated nucleic acid testing system to enable TB diagnosis in peripheral settings

To facilitate treatment and limit transmission of tuberculosis (TB), new methods are needed to enable rapid and affordable diagnosis of the disease in high-burden low-resource settings. We have developed a prototype integrated nucleic acid testing device to detect Mycobacterium tuberculosis (M.tb) in sputum. The device consists of a disposable cartridge and compact, inexpensive instrument that automates pathogen lysis, nucleic acid extraction, isothermal DNA amplification and lateral flow detection. A liquefied and disinfected sputum sample is manually injected into the cartridge, and all other steps are automated, with a result provided in <1.5 h. Cell disruption and DNA extraction is executed within a four-port active valve containing a miniature bead blender (based on PureLyse® technology, Claremont BioSolutions LLC). The DNA-containing eluate is combined with dry master-mix reagents and target DNA is isothermally amplified. Amplified master-mix is then pumped into a lateral flow strip chamber for detection. The entire process is performed in a single-use closed-system cartridge to prevent amplicon carryover. For testing of M.tb-spiked sputum the system provided a limit of detection of 5 × 103 colony forming units (CFU) per mL. None of the negative sputum-only controls yielded a false-positive result. Testing of 45 clinical sputum specimens from TB cases and controls relative to a validated manual qPCR-based comparator method revealed a preliminary sensitivity of 90% and specificity of 96%. With further development, the herein described integrated nucleic acid testing device can enable TB diagnosis and treatment initiation in the same clinical encounter in near-patient low-resource settings of high TB burden countries.

Transparent Microcrystalline Cellulose/Polyvinyl Alcohol Paper as a New Platform for Three-Dimensional Cell Culture

Multilayered and stacked cellulose paper has emerged as a promising platform for construction of three-dimensional (3D) cell culture because of its low cost, good biocompatibility, and high porosity. However, its poor light transmission makes it challenging to directly and clearly monitor cell behaviors (e.g., growth and proliferation) on the paper-based platform using an optical microscope. In this work, we developed a transparent microcrystalline cellulose/polyvinyl alcohol (MCC/PVA) paper with irregular pores through dissolution and regeneration of microcrystalline nanocellulose, addition of a porogen reagent (NaCl), and subsequently dipping in PVA solutions. The transparent MCC paper displays high porosity (up to 90%), adjustable pore size (between 23 and 46 μm), large thickness (from 315 to 436 μm), and high light transmission under water (>95%). Through further modification of the transparent MCC paper with PVA, the obtained transparent MCC/PVA paper shows enhanced mechanical properties (dry and wet strengths), good hydrophilicity (with a contact angle of 70.8°), and improved biocompatibility (cell viability up to 90%). By stacking and destacking multiple layers of the transparent MCC/PVA paper, it has been used for both two-dimensional and three-dimensional cell culture platforms. The transparent MCC/PVA paper under water enables both direct observation of cell morphology by an optical microscope via naked eyes and fluorescence microscope after staining. We envision that the developed transparent MCC/PVA paper holds great potential for future applications in various bioanalytical and biomedical fields, such as drug screening, tissue engineering, and organ-on-chips.

Enclosed paper-based analytical devices: Concept, variety, and outlook

Paper-based analytical devices possess desirable properties such as low cost, convenient production, and rapid output. These advantages over conventional analytical devices have attracted tremendous attention in recent years, and an abundance of fabrication techniques have been achieved with different designs. Related approaches are adopted by scientists and engineers from different research fields to create practical devices tailored for various applications. Among a diverse selection of strategies, paper-based analytical devices featuring enclosed channels can protect its contents from environmental harm, which is helpful in designing paper-based devices aimed toward practical use. However, superior properties of enclosed device designs have often been neglected when a paper-based platform is selected, and related discussion is still lacking in the field. To fill this empty space in the relevant literature, important issues are highlighted and recent research achievements are included in this article, which should have implication for scientists interested in sensing technology, analytical chemistry, material science, and miniaturized devices. For the convenience of reader's understanding, this article provides a general introduction to the basic properties and concepts of paper-based analytical devices. Firstly, commonly used fabrication strategies and detection methods are mentioned, with an in-depth emphasis on paper-based devices with enclosed channels, including breakthroughs in device types, thoughts on novel fabrication, and practical application examples. Subsequently, other important topics related to enclosed paper-based device design are summarized, and future challenges and opportunities in the field are also discussed.

Usability as a guiding principle for the design of paper-based, point-of-care devices - A review

Due to their portability, versatility for supporting multiple assay formats, and potential for resulting in low-cost assays, paper-based analytical devices (PADs) are an increasingly popular format as a platform for the development of point-of-care tests. However, very few PADs have been translated successfully to their intended environments outside of academic settings. Often overlooked as a factor that inhibits translation, usability is a vital characteristic of any successful point-of-care test. Recent advancements in PAD design have demonstrated improved usability by simplifying various aspects of user operation, including sample collection, sample processing, device operation, detection, and readout/interpretation. Field testing at various stages of device design can offer critical feedback about device usability, especially when it involves the proposed end-user or other stakeholders. By highlighting advances in usability, we aim to encourage thoughtful and rigorous design at the academic prototyping stage to address one outstanding hurdle that limits the number of PADs that make it from the benchtop to the point-of-care.

Thread- and Capillary Tube-Based Electrodes for the Detection of Glucose and Acetylthiocholine

An electrochemical sensor for the detection of glucose and acetylthiocholine (ATC) using thread- and capillary tube-based electrodes is described. Three nylon thread-based electrodes were fabricated by painting pieces of trifurcated nylon thread with conductive inks and threading the electrodes into capillary tubes. Two platforms, one paper-based and the other utilizing bubble wrap, were examined. For the glucose detection, a solution containing glucose oxidase (GOx), potassium ferricyanide (K3[Fe(CN)6]), and increasing concentrations of glucose (0-20 mM) in phosphate-buffered saline (PBS) was spotted onto the two platforms. Similarly, increasing concentrations of ATC (0-9.84 mg/mL) in acetylcholinesterase (AChE) (0.08 U/mL) and PBS solution were detected. Using cyclic voltammetry (CV), a scanning voltage was applied to yield a graph of voltage applied (V) vs. current output (A). For both platforms, both glucose and ATC concentrations were observed to be linearly proportional to the current output as demonstrated by the increased height of the oxidation peaks. The three-electrode system was simple to fabricate, inexpensive, and could be used for multiple readings.

SNAPflex: a paper-and-plastic device for instrument-free RNA and DNA extraction from whole blood

Nucleic acid amplification tests (NAATs), which amplify and detect pathogen nucleic acids, are vital methods to diagnose diseases, particularly in cases where patients exhibit low levels of infection. For many blood-borne pathogens such as HIV or Plasmodium falciparum, it is necessary to first extract pathogen RNA or DNA from patient blood prior to NAAT analysis. Traditional nucleic acid extraction methods are expensive, resource-intensive and are often difficult to deploy to resource-limited areas where many blood-borne infections are widespread. Here, we describe a portable, paper-and-plastic device, called SNAPflex, for instrument-free nucleic acid extraction from whole blood, which builds upon our previous work for RNA extraction using a pressure-driven extraction system. SNAPflex shows improved HIV RNA extraction from simulated patient samples compared to traditional extraction methods as well as long-term stability of extracted RNA without the need for cold storage. We further demonstrated successful extraction and recovery of P. falciparum DNA from cultured parasites in whole blood. SNAPflex was designed to be easily manufacturable and deployable to resource-limited settings.

An Integrated Smartphone-Based Genetic Analyzer for Qualitative and Quantitative Pathogen Detection

The use of the smartphone is an ideal platform to realize the future point-of-care (POC) diagnostic system. Herein, we propose an integrated smartphone-based genetic analyzer. It consists of a smartphone and an integrated genetic analysis unit (i-Gene), in which the power of the smartphone was utilized for heating the gene amplification reaction, and the camera function was used for imaging the colorimetric change of the reaction for quantitative and multiplex foodborne pathogens. The housing of i-Gene was fabricated by using a 3D printer, which was equipped with a macro lens, white LEDs, a disposable microfluidic chip for loop-mediated isothermal amplification (LAMP), a thin-film heater, and a power booster. The i-Gene was installed on the iPhone in alignment with a camera. The LAMP mixture for Eriochrome Black T (EBT) colorimetric detection was injected into the LAMP chip to identify Escherichia coli O157:H7, Salmonella typhimurium, and Vibrio parahaemolyticus. The proportional-integral-derivative controller-embedded film heater was powered by a 5.0 V power bank to maintain 63 °C for the LAMP reaction. When the LAMP proceeded, the color was changed from violet to blue, which was real-time monitored by the smartphone complementary metal oxide semiconductor camera. The images were transported to the desktop computer via Wi-Fi. The quantitative LAMP profiles were obtained by plotting the ratio of green/red intensity versus the reaction time. We could identify E. coli O157:H7 with a limit of detection of 10¹ copies/μL within 60 min. Our proposed smartphone-based genetic analyzer offers a portable, simple, rapid, and cost-effective POC platform for future diagnostic markets.

Fighting COVID-19: Integrated Micro- and Nanosystems for Viral Infection Diagnostics

The pandemic of coronavirus disease 2019 (COVID-19) highlights the importance of rapid and sensitive diagnostics of viral infection that enables the efficient tracing of cases and the implementation of public health measures for disease containment. The immediate actions from both academia and industry have led to the development of many COVID-19 diagnostic systems that have secured fast-track regulatory approvals and have been serving our healthcare frontlines since the early stage of the pandemic. On diagnostic technologies, many of these clinically validated systems have significantly benefited from the recent advances in micro- and nanotechnologies in terms of platform design, analytical method, and system integration and miniaturization. The continued development of new diagnostic platforms integrating micro- and nanocomponents will address some of the shortcomings we have witnessed in the existing COVID-19 diagnostic systems. This Perspective reviews the previous and ongoing research efforts on developing integrated micro- and nanosystems for nucleic acid-based virus detection, and highlights promising technologies that could provide better solutions for the diagnosis of COVID-19 and other viral infectious diseases. With the summary and outlook of this rapidly evolving research field, we hope to inspire more research and development activities to better prepare our society for future public health crises.

Recent Advances in Microfluidic Paper-Based Analytical Devices toward High-Throughput Screening

Microfluidic paper-based analytical devices (µPADs) have become promising tools offering various analytical applications for chemical and biological assays at the point-of-care (POC). Compared to traditional microfluidic devices, µPADs offer notable advantages; they are cost-effective, easily fabricated, disposable, and portable. Because of our better understanding and advanced engineering of µPADs, multistep assays, high detection sensitivity, and rapid result readout have become possible, and recently developed µPADs have gained extensive interest in parallel analyses to detect biomarkers of interest. In this review, we focus on recent developments in order to achieve µPADs with high-throughput capability. We discuss existing fabrication techniques and designs, and we introduce and discuss current detection methods and their applications to multiplexed detection assays in relation to clinical diagnosis, drug analysis and screening, environmental monitoring, and food and beverage quality control. A summary with future perspectives for µPADs is also presented.

Lab-on-paper for all-in-one molecular diagnostics (LAMDA) of zika, dengue, and chikungunya virus from human serum

Several tropical fever viruses transmitted by mosquitoes including zika, dengue, and chikungunya, are becoming a serious problem in global public health. Simple diagnostic tools in early stages are strongly required to monitor and prevent these diseases. Paper diagnostic platforms can provide a solution for these needs, with integration of fluidic control techniques and isothermal amplification methods. Here, we demonstrate a Lab-on-paper for all-in-one molecular diagnostics of zika, dengue, and chikungunya virus from human serum. The entire process of nucleic acid testing that involves sampling, extraction, amplification, and detection is simply operated on a single paper chip. Based on the engineered structure of paper materials and dried chemicals on the all-in-one chip, serum samples containing the target virus RNA were simply added by automatic flow from distilled water injection. Target RNA molecules were concentrated on the binding pad with chitosan and then transported to reaction pads following a pH increase for specific reverse transcription loop-mediated isothermal amplification with fluorescence signal generation. Three targets, zika virus, dengue virus, and chikungunya virus, in human serum were simultaneously detected on the all-in-one paper chip within 60 min at 65 °C. The all-in-one paper chip can be used as a real-time quantitative assay for 5-5000 copies of zika virus RNA. This all-in-one device was successfully used with 5 clinical specimens of zika and dengue virus from real patients. We believe that the proposed all-in-one paper chip can provide a portable, low-cost, user-friendly, sensitive, and specific NAT platform with great potential in point-of-care diagnostics.

Fast DNA Extraction with Polyacrylamide Microspheres for Polymerase Chain Reaction Detection

The fast and cost-effective DNA extraction is critical for all DNA-based detections. Here, we fabricated a new kind of polyacrylamide microsphere (PAMMP) in various sizes with two methods, spot polymerization (large size but low yield) and modified inverse microemulsion polymerization (small size but high yield). The fabricated PAMMPs have strong autofluorescence (fPAMMPs), including both visible fluorescence (VF) and near-infrared fluorescence (NIRF), which can remain very stable in various stringent conditions including strong acid and alkali and high temperature. The fabricated fPAMMPs were also highly positively charged, which could be used to effectively capture various biomolecules such as IRDye 800-labeled streptavidin and DNA. We thus developed a new method for rapid extraction (3-5 min) of DNA from various samples including bacteria, mammalian cells, plant and animal solid tissues, and human blood plasma using fPAMMPs. Moreover, the DNA captured on fPAMMPs (fPAMMP@DNA) could be effectively detected by both normal and quantitative PCR amplifications. Finally, we showed that NaBH₄ treatment removed autofluorescence in fPAMMPs (PAMMPs), which could also be applied to DNA extraction and PCR detection. In conclusion, we here fabricated new kinds of fPAMMPs and PAMMPs, developed a new rapid DNA extraction method, and demonstrated their useful applications in PCR detection.

Water and microbial monitoring technologies towards the near future space exploration

Space exploration is demanding longer lasting human missions and water resupply from Earth will become increasingly unrealistic. In a near future, the spacecraft water monitoring systems will require technological advances to promptly identify and counteract contingent events of waterborne microbial contamination, posing health risks to astronauts with lowered immune responsiveness. The search for bio-analytical approaches, alternative to those applied on Earth by cultivation-dependent methods, is pushed by the compelling need to limit waste disposal and avoid microbial regrowth from analytical carryovers. Prospective technologies will be selected only if first validated in a flight-like environment, by following basic principles, advantages, and limitations beyond their current applications on Earth. Starting from the water monitoring activities applied on the International Space Station, we provide a critical overview of the nucleic acid amplification-based approaches (i.e., loop-mediated isothermal amplification, quantitative PCR, and high-throughput sequencing) and early-warning methods for total microbial load assessments (i.e., ATP-metry, flow cytometry), already used at a high readiness level aboard crewed space vehicles. Our findings suggest that the forthcoming space applications of mature technologies will be necessarily bounded by a compromise between analytical performances (e.g., speed to results, identification depth, reproducibility, multiparametricity) and detrimental technical requirements (e.g., reagent usage, waste production, operator skills, crew time). As space exploration progresses toward extended missions to Moon and Mars, miniaturized systems that also minimize crew involvement in their end-to-end operation are likely applicable on the long-term and suitable for the in-flight water and microbiological research.

A fully integrated hand-powered centrifugal microfluidic platform for ultra-simple and non-instrumental nucleic acid detection

Hand-powered centrifugal microfluidics combined with isothermal nucleic acid amplification testing (NAAT) have been one of the most promising rapid detection platforms in resource-limited settings. However, current hand-powered centrifuges still suffer from customized instrument-based operation and low rotation rate; and most isothermal NAAT were conducted with complicated reaction systems for DNA detection and required an additional step for RNA detection. Herein, we built a fully hand-powered centrifugal miniaturized NAAT platform inspired by buzzer toys, which embedded sample preparation, strand exchange amplification (SEA) and visual fluorescence detection together. The centrifugal disc was easily fabricated, and operated the mixing in 1 min by simply dragging the looped rope through it with a mean input force of 16.5 N, enabling its rotation rate reach 5000 rpm. In addition, SEA was an ultra-simple one-step DNA or RNA detection method initiated by Bst DNA polymerase and a pair of primers, and thus we took all its merits and integrate it into microfluidic systems firstly. Furthermore, taking Vibrio parahemolyticus as an example, the microfluidic platform achieved DNA or RNA detection within 1 h; and the detection limit of the microchip for artificially spiked oysters was 10³ CFU/g without cumbersome sample preparation, and reached to 10⁰ CFU/g after enrichment. Therefore, we provided an ultra-simple and non-instrumental microfluidic platform powered merely by hands, performing general potential in sample-to-answer NAAT for versatile pathogens in remote regions.

Method for the elucidation of LAMP products captured on lateral flow strips in a point of care test for HPV 16

Loop-mediated amplification (LAMP) is an isothermal amplification technique favored in diagnostics and point-of-care work due to its high sensitivity and ability to run in isothermal conditions. In addition, a visual readout by lateral flow strips (LFS) can be used in conjunction with LAMP, making the assay accessible at the point-of-care. However, the amplicons resulting from a LAMP reaction varied in length and shape, making them undiscernible on a double-stranded DNA intercalating dye stained gel. Standard characterization techniques also do not identify which amplicons specifically bind to the LFS, which generate the visual readout. We aimed to standardize our characterization of LAMP products during assay development by using fluorescein amidite (FAM) and biotin-tagged loop forward and backward primers during assay development. A pvuII restriction enzyme digest is applied to the LAMP products. FAM-tagged bands are directly correlated with the LFS visual readout. We applied this assay development workflow for an HPV 16 assay using both plasmid DNA and clinical samples to demonstrate proof of concept for generalized assay development work.

Electrochemical Detection of Genomic DNA Utilizing Recombinase Polymerase Amplification and Stem-Loop Probe

Nucleic acid tests integrated into digital point-of-care (POC) diagnostic systems have great potential for the future of health care. However, current methods of DNA amplification and detection require bulky and expensive equipment, many steps, and long process times, which complicate their integration into POC devices. We have combined an isothermal DNA amplification method, recombinase polymerase amplification, with an electrochemical stem-loop (S-L) probe DNA detection technique. By combining these methods, we have created a system that is able to specifically amplify and detect as few as 10 copies/μL Staphylococcus epidermidis DNA with a total time to result of 70-75 min.

Development of Point-of-Care Biosensors for COVID-19

Coronavirus disease 2019 (COVID-19) outbreak has become a global pandemic. The deleterious effects of coronavirus have prompted the development of diagnostic tools to manage the spread of disease. While conventional technologies such as quantitative real time polymerase chain reaction (qRT-PCR) have been broadly used to detect COVID-19, they are time-consuming, labor-intensive and are unavailable in remote settings. Point-of-care (POC) biosensors, including chip-based and paper-based biosensors are typically low-cost and user-friendly, which offer tremendous potential for rapid medical diagnosis. This mini review article discusses the recent advances in POC biosensors for COVID-19. First, the development of POC biosensors which are made of polydimethylsiloxane (PDMS), papers, and other flexible materials such as textile, film, and carbon nanosheets are reviewed. The advantages of each biosensors along with the commercially available COVID-19 biosensors are highlighted. Lastly, the existing challenges and future perspectives of developing robust POC biosensors to rapidly identify and manage the spread of COVID-19 are briefly discussed.

Dynamic Aqueous Multiphase Reaction System for One-Pot CRISPR-Cas12a-Based Ultrasensitive and Quantitative Molecular Diagnosis

Recently, CRISPR-Cas technology has opened a new era of nucleic acid-based molecular diagnostics. However, current CRISPR-Cas-based nucleic acid biosensing has a lack of the quantitative detection ability and typically requires separate manual operations. Herein, we reported a dynamic aqueous multiphase reaction (DAMR) system for simple, sensitive and quantitative one-pot CRISPR-Cas12a based molecular diagnosis by taking advantage of density difference of sucrose concentration. In the DAMR system, recombinase polymerase amplification (RPA) and CRISPR-Cas12a derived fluorescent detection occurred in spatially separated but connected aqueous phases. Our DAMR system was utilized to quantitatively detect human papillomavirus (HPV) 16 and 18 DNAs with sensitivities of 10 and 100 copies within less than 1 h. Multiplex detection of HPV16/18 in clinical human swab samples were successfully achieved in the DAMR system using 3D-printed microfluidic device. Furthermore, we demonstrated that target DNA in real human plasma samples can be directly amplified and detected in the DAMR system without complicated sample pretreatment. As demonstrated, the DAMR system has shown great potential for development of next-generation point-of-care molecular diagnostics.

Advances in HIV diagnosis and monitoring

Although highly active antiretroviral therapy (HAART) has been introduced over twenty years ago to treat Human Immunodeficiency Virus (HIV) positive patients, acquired immunodeficiency syndrome (AIDS) is still one of the deadliest diseases found worldwide. AIDS prevalence and mortality rates are usually more pronounced in resource-constrained countries than in the developed world. The lack of trained medical technicians, sophisticated diagnostic equipment, and the overall scarcity of medical infrastructures have severely impacted HIV/AIDS diagnostics, which hinders the initiation and periodic monitoring of antiretroviral therapy (ART). Currently, available HIV viral load assays are not well-suited for resource-limited settings due to their high cost and a requirement for medical/technical infrastructures. In this paper, we review current and emerging diagnostic assays for HIV detection, with a focus on point-of-care (POC) based immunoassays for viral load measurement, drug resistance, and HIV recurrence. We also discuss the limitations of the available HIV assays and highlight the technological advancements in cellphone, paper, and flexible material-based assays which have the potential to improve HIV diagnosis and monitoring, thus assisting with the management of the disease.

A Loop-Mediated Isothermal Amplification Assay for the Detection of Treponema pallidum subsp. pertenue

The eradication of yaws caused by Treponema pallidum subsp. pertenue is constrained by the lack of rapid, accurate diagnosis. We sought to develop a molecular point-of-care test for the diagnosis of yaws. A loop-mediated isothermal amplification (LAMP) assay with primers targeting the conserved gene, tp0967, with visual detection by lateral flow test strip was developed and optimized. The limit of detection was evaluated while 63 samples from clinical cases of yaws and five samples with polymerase chain reaction (PCR)-confirmed syphilis were used to determine the sensitivity and specificity of the assay compared with the current molecular testing protocol. The developed LAMP assay was found to be optimal when run at 65°C for 30 minutes. The limit of detection from extracted DNA was 2.7 × 10⁴ DNA copies/mL. The sensitivity of the LAMP assay using unextracted and DNA extracted samples were 0.67 and 1.00, respectively. None of the syphilis samples tested positive in any of the assays. We show the development of a fast and sensitive LAMP assay for yaws detected by lateral flow test strip. Using extracted DNA, the assay sensitivity is at par with real-time PCR-based detection. The assay can be adapted to minimal sample processing required for infield detection without DNA extraction.

Development of a cost-efficient micro-detection slide system for the detection of multiple shrimp pathogens

In view of the current demand for rapid detection and identification of pathogens, point-of-care testing (POCT) with fast portability, low consumption, and increased sensitivity and specificity has become more and more popular. The emerging nucleic acid isothermal amplification technology (NAIAT) has shown potential advantages in the development of rapid microbial detection. In this study, a micro-detection slide system was developed based on the NAIAT of various nucleic acids of shrimp pathogens. The system included a micro-detection slide with 48 identical detecting cells precoated with all detection reagents, except the sample template. The process of producing the micro-detection slides mainly combined super-hydrophobic/super-oleophobic and super-hydrophilic materials to obtain separated spaces for detection, and aerosol pollution was eliminated in the form of water-in-oil. The micro-detection slide system was capable of simultaneously detecting 4 groups of samples and 8 important shrimp pathogens and is a relatively low-cost, portable, and high-throughput nucleic acid (RNA and DNA) detection technology. The establishment of this technology will provide key technical support for the construction of biosecurity systems for healthy shrimp culture.

Paper-based nuclease protection assay with on-chip sample pretreatment for point-of-need nucleic acid detection

Pathogen detection is crucial for human, animal, and environmental health; crop protection; and biosafety. Current culture-based methods have long turnaround times and lack sensitivity. Nucleic acid amplification tests offer high specificity and sensitivity. However, their cost and complexity remain a significant hurdle to their applications in resource-limited settings. Thus, point-of-need molecular diagnostic platforms that can be used by minimally trained personnel are needed. The nuclease protection assay (NPA) is a nucleic acid hybridization-based technique that does not rely on amplification, can be paired with other methods to improve specificity, and has the potential to be developed into a point-of-need device. In traditional NPAs, hybridization of an anti-sense probe to the target sequence is followed by single-strand nuclease digestion. The double-stranded target-probe hybrids are protected from nuclease digestion, precipitated, and visualized using autoradiography or other methods. We have developed a paper-based nuclease protection assay (PB-NPA) that can be implemented in field settings as the detection approach requires limited equipment and technical expertise. The PB-NPA uses a lateral flow format to capture the labeled target-probe hybrids onto a nitrocellulose membrane modified with an anti-label antibody. A colorimetric enzyme-substrate pair is used for signal visualization, producing a test line. The nuclease digestion of non-target and mismatched DNA provides high specificity while signal amplification with the reporter enzyme-substrate provides high sensitivity. We have also developed an on-chip sample pretreatment step utilizing chitosan-modified paper to eliminate possible interferents from the reaction and preconcentrate nucleic acids, thereby significantly reducing the need for auxiliary equipment. Graphical abstract.

Paper-based microfluidics for rapid diagnostics and drug delivery

Paper is a common material that is promising for constructing microfluidic chips (lab-on-a-paper) for diagnostics and drug delivery for biomedical applications. In the past decade, extensive research on paper-based microfluidics has accumulated a large number of scientific publications in the fields of biomedical diagnosis, food safety, environmental health, drug screening and delivery. This review focuses on the recent progress on paper-based microfluidic technology with an emphasis on the design, optimization and application of the technology platform, in particular for medical diagnostics and drug delivery. Novel advances have concentrated on engineering paper devices for point-of-care (POC) diagnostics, which could be integrated with nucleic acid-based tests and isothermal amplification experiments, enabling rapid sample-to-answer assays for field testing. Among the isothermal amplification experiments, loop-mediated isothermal amplification (LAMP), an extremely sensitive nucleic acid test, specifically identifies ultralow concentrations of DNA/RNA from practical samples for diagnosing diseases. We thus mainly focus on the paper device-based LAMP assay for the rapid infectious disease diagnosis, foodborne pathogen analysis, veterinary diagnosis, plant diagnosis, and environmental public health evaluation. We also outlined progress on paper microfluidic devices for drug delivery. The paper concludes with a discussion on the challenges of this technology and our insights into how to advance science and technology towards the development of fully functional paper devices in diagnostics and drug delivery.

Recent Advances of Fluid Manipulation Technologies in Microfluidic Paper-Based Analytical Devices (μPADs) toward Multi-Step Assays

Microfluidic paper-based analytical devices (μPADs) have been suggested as alternatives for developing countries with suboptimal medical conditions because of their low diagnostic cost, high portability, and disposable characteristics. Recently, paper-based diagnostic devices enabling multi-step assays have been drawing attention, as they allow complicated tests, such as enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR), which were previously only conducted in the laboratory, to be performed on-site. In addition, user convenience and price of paper-based diagnostic devices are other competitive points over other point-of-care testing (POCT) devices, which are more critical in developing countries. Fluid manipulation technologies in paper play a key role in realizing multi-step assays via μPADs, and the expansion of biochemical applications will provide developing countries with more medical benefits. Therefore, we herein aimed to investigate recent fluid manipulation technologies utilized in paper-based devices and to introduce various approaches adopting several principles to control fluids on papers. Fluid manipulation technologies are classified into passive and active methods. While passive valves are structurally simple and easy to fabricate, they are difficult to control in terms of flow at a specific spatiotemporal condition. On the contrary, active valves are more complicated and mostly require external systems, but they provide much freedom of fluid manipulation and programmable operation. Both technologies have been revolutionized in the way to compensate for their limitations, and their advances will lead to improved performance of μPADs, increasing the level of healthcare around the world.

Polymerization-Based Amplification for Target-Specific Colorimetric Detection of Amplified Mycobacterium tuberculosis DNA on Cellulose

Loop-mediated isothermal amplification (LAMP) is an appealing method for low-cost, point-of-care nucleic acid diagnostic assays due to high sensitivity, minimal equipment requirements, and compatibility with user-friendly colorimetric detection methods. The enhanced sensitivity LAMP offers comes with vulnerability to cross-contamination, where negative samples are exposed to minute amounts of nucleic acids from positive samples. These amounts are insignificant in less sensitive amplification methods, but visible when LAMP is paired with common colorimetric methods. Here, we examined the use of eosin photopolymerization, a tunable reaction, for colorimetric detection of LAMP products to reduce this false positive risk. Using eosin and biotin end-labeled primers, we successfully amplified target regions of the Mycobacterium tuberculosis (MTB) genome using PCR and LAMP, captured amplicons on streptavidin-coated cellulose, and detected DNA targets via eosin photopolymerization, producing a bright pink color only if MTB DNA was present in the sample. Consistent with previous reports, the LAMP-based method exhibited high background signal, but tuning the illumination time for the photopolymerization reaction allowed readouts from samples with no added MTB DNA to remain blank and visually distinct from pink positives. This method yielded limits of detection of 30 and 300 copies/μL for LAMP and PCR amplification, respectively. When confronted with boiled MTB culture samples, this method gave clear positive readouts, compared to negligible signal from other Mycobacterium boiled culture samples. This new method of LAMP colorimetric detection has the potential to increase the utility of LAMP as a nucleic acid assay technique by mitigating sensitivity to cross-contamination.

Development of Low-Cost Point-of-Care Technologies for Cervical Cancer Prevention Based on a Single-Board Computer

Cervical cancer disproportionally affects women in low- and middle-income countries, in part due to the difficulty of implementing existing cervical cancer screening and diagnostic technologies in low-resource settings. Single-board computers offer a low-cost alternative to provide computational support for automated point-of-care technologies. Here we demonstrate two new devices for cervical cancer prevention that use a single-board computer: 1) a low-cost imaging system for real-time detection of cervical precancer and 2) a low-cost reader for real-time interpretation of lateral flow-based molecular tests to detect cervical cancer biomarkers. Using a Raspberry Pi computer to provide real-time image collection and processing, we developed: 1) a low-cost, portable high-resolution microendoscope system (PiHRME); and 2) a low-cost automatic lateral flow test reader (PiReader). The PiHRME acquired high-resolution ([Formula: see text]) images of the cervix at half the cost of existing high-resolution microendoscope systems; image analysis algorithms based on convolutional neural networks were implemented to provide real-time image interpretation. The PiReader acquired and analyzed images of a point-of-care human papillomavirus (HPV) serology test with the same contrast and accuracy as a standard flatbed high-resolution scanner coupled to a laptop computer, for less than one-fifth of the cost. Raspberry Pi single-board computers provide a low-cost means to implement point-of-care tools with automatic image analysis. This work demonstrates the promise of single-board computers to develop and translate low-cost, point-of-care technologies for use in low-resource settings.

Estimates of incidence and mortality of cervical cancer in 2018: a worldwide analysis

BACKGROUND

The knowledge that persistent human papillomavirus (HPV) infection is the main cause of cervical cancer has resulted in the development of prophylactic vaccines to prevent HPV infection and HPV assays that detect nucleic acids of the virus. WHO has launched a Global Initiative to scale up preventive, screening, and treatment interventions to eliminate cervical cancer as a public health problem during the 21st century. Therefore, our study aimed to assess the existing burden of cervical cancer as a baseline from which to assess the effect of this initiative.

METHODS

For this worldwide analysis, we used data of cancer estimates from 185 countries from the Global Cancer Observatory 2018 database. We used a hierarchy of methods dependent on the availability and quality of the source information from population-based cancer registries to estimate incidence of cervical cancer. For estimation of cervical cancer mortality, we used the WHO mortality database. Countries were grouped in 21 subcontinents and were also categorised as high-resource or lower-resource countries, on the basis of their Human Development Index. We calculated the number of cervical cancer cases and deaths in a given country, directly age-standardised incidence and mortality rate of cervical cancer, indirectly standardised incidence ratio and mortality ratio, cumulative incidence and mortality rate, and average age at diagnosis.

FINDINGS

Approximately 570 000 cases of cervical cancer and 311 000 deaths from the disease occurred in 2018. Cervical cancer was the fourth most common cancer in women, ranking after breast cancer (2·1 million cases), colorectal cancer (0·8 million) and lung cancer (0·7 million). The estimated age-standardised incidence of cervical cancer was 13·1 per 100 000 women globally and varied widely among countries, with rates ranging from less than 2 to 75 per 100 000 women. Cervical cancer was the leading cause of cancer-related death in women in eastern, western, middle, and southern Africa. The highest incidence was estimated in Eswatini, with approximately 6·5% of women developing cervical cancer before age 75 years. China and India together contributed more than a third of the global cervical burden, with 106 000 cases in China and 97 000 cases in India, and 48 000 deaths in China and 60 000 deaths in India. Globally, the average age at diagnosis of cervical cancer was 53 years, ranging from 44 years (Vanuatu) to 68 years (Singapore). The global average age at death from cervical cancer was 59 years, ranging from 45 years (Vanuatu) to 76 years (Martinique). Cervical cancer ranked in the top three cancers affecting women younger than 45 years in 146 (79%) of 185 countries assessed.

INTERPRETATION

Cervical cancer continues to be a major public health problem affecting middle-aged women, particularly in less-resourced countries. The global scale-up of HPV vaccination and HPV-based screening-including self-sampling-has potential to make cervical cancer a rare disease in the decades to come. Our study could help shape and monitor the initiative to eliminate cervical cancer as a major public health problem.

FUNDING

Belgian Foundation Against Cancer, DG Research and Innovation of the European Commission, and The Bill & Melinda Gates Foundation.