Simple Approaches to Minimally-Instrumented, Microfluidic-Based Point-of-Care Nucleic Acid Amplification Tests

Mini Review on the Lyophilization: A Basic Requirement for Formulation Development and Stability Modifier

Freeze-drying is popular for producing pharmaceutical formulations with structurally complicated active components and drug delivery system carriers. It is the process of eliminating water from ice crystals through the sublimation mechanism. Some formulations may require drug-specific excipients such as stabilizers, buffers, and bulking agents to maintain the appearance and assure the long-term stability of the drug product. This approach is utilized for therapeutic compounds that are moisture sensitive, thermolabile, and degrade in the atmosphere. Freezing and primary and secondary drying are critical processes in the lyophilization process because they directly impact the end result. This approach is effective for producing a variety of dosage forms, including oral, inhalation, and parenteral. As a result, lyophilization may be an important method for improving the therapeutic efficacy and delivery of various dosage forms delivered via different routes. Additionally, lyophilization is used in pharmacological research to preserve biological samples, stabilize reference/standards, and increase the solubility and bioavailability of poorly soluble drugs. Thus, lyophilization is critical for maintaining the stability, efficacy, and safety of pharmaceutical products throughout their development and lifecycles. This article includes a broad overview of the lyophilization process, principle, excipients for lyophilized medicine compositions, and new lyophilization technologies as well as their applications in a variety of fields.

An open source, PCR based, point-of-care testing platform

In recent years, point-of-care nucleic acid testing had played an important role in the diagnosis of infectious diseases. Despite its advantages, current point-of-care testing (POCT) platforms were all closed, which hindered researchers from quickly validating the performance of customized reagents. Incompatibility and repeated development of different POCT devices also resulted in the waste of medical resources. In this article, a rotating cartridge with a detachable reagent rack was developed, which provided an open platform in conjunction with a programmable POCT instrument. The system had been confirmed to effectively detect the HPV sample with a concentration of 1000 copies per milliliter and the novel coronavirus nucleic acid control dilution with a concentration of 200 copies per milliliter within 1 h. The cartridge could detect six targets simultaneously and cost less than ten dollars. The square of the correlation coefficients of the fitting line between the dye concentration and the fluorescence intensity all exceeded 0.99. The coefficient of variation (CV) for testing one sample with multiple cartridges or instruments was under 3%, confirming the stability and reliability of system performance. Results of clinical testing further verified its ability to detect multiple viruses, including novel coronavirus, influenza and human papillomavirus. Compared with standard results, the sensitivity reached 100% in the detection of multiple respiratory viruses and HPV viruses while the specificity was above 98% for all targets. The area under the curve (AUC) values for all receiver operating characteristic (ROC) curves exceeded 0.98. These results indicated that this platform had excellent performances and provided a competitive solution for low-cost, open point-of-care nucleic acid testing.

Self-actuated microfluidic chiplet for two-stage multiplex nucleic acid amplification assay

Effective diagnosis of comorbidities and infectious diseases that present similar symptoms requires point-of-need assays capable of co-detecting and differentiating among multiple co-endemic pathogens to enable timely, precision medicine and effective control measures. We previously developed a two-stage isothermal amplification assay dubbed Penn-RAMP to address this need. Penn-RAMP's first stage comprises a recombinase polymerase amplification (RPA), which amplifies all targets of interest in a single reaction chamber for a short duration. The RPA amplicons are then aliquoted into multiple loop-mediated isothermal amplification (LAMP) reaction chambers, each customized with pre-dried primers to amplify a single target or a group of targets. To enable Penn-RAMP at the point of need, we describe here a self-actuated Penn-RAMP chiplet that accommodates the Penn-RAMP assay. Our chiplet employs temperature-controlled phase change valves and capillary valves to self-aliquot first-stage amplicons into multiple (five) second-stage reaction chambers and to seal these chambers. The functionality of our device is demonstrated by co-detecting plant pathogens. The analytical performance of our chiplet is comparable to that of the benchtop Penn-RAMP assay and surpasses that of standalone LAMP assays. Our self-actuated chiplet can be operated standalone with purified nucleic acids or as the downstream amplification module of a sample preparation cassette.

Isothermal Technologies for HPV Detection: Current Trends and Future Perspectives

The human papillomavirus (HPV) is a non-enveloped DNA virus transmitted through skin-to-skin contact that infects epithelial and mucosal tissue. It has over 200 known genotypes, classified by their pathogenicity as high-risk and low-risk categories. High-risk HPV genotypes are associated with the development of different types of cancers, including cervical cancer, which is a leading cause of mortality in women. In clinical practice and the market, the principal tests used to detect HPV are based on cytology, hybrid detection, and qPCR. However, these methodologies may not be ideal for the required timely diagnosis. Tests have been developed based on isothermal nucleic acid amplification tests (INAATs) as alternatives. These tests offer multiple advantages over the qPCR, such as not requiring specialized laboratories, highly trained personnel, or expensive equipment like thermocyclers. This review analyzes the different INAATs applied for the detection of HPV, considering the specific characteristics of each test, including the HPV genotypes, gene target, the limit of detection (LOD), detection methods, and detection time. Additionally, we discuss the tests available on the market that are approved by the Food and Drug Administration (FDA). Finally, we address the challenges and potential solutions for the large-scale implementation of INAATs, particularly in rural or underserved areas.

Extensively and multidrug-resistant bacterial strains: case studies of antibiotics resistance

The development of antibiotic resistance compromises the effectiveness of our most effective defenses against bacterial infections, presenting a threat to global health. To date, a large number of research articles exist in the literature describing the case reports associated with extensively drug-resistant (XDR) and multidrug-resistant (MDR) bacterial strains. However, these findings are scattered, making it time-consuming for researchers to locate promising results and there remains a need for a comparative study to compile these case reports from various geographical regions including the Kingdom of Saudi Arabia. Additionally, no study has yet been published that compares the genetic variations and case reports of MDR and XDR strains identified from Saudi Arabia, the Middle East, Central Europe, and Asian countries. This study attempts to provide a comparative analysis of several MDR and XDR case reports from Saudi Arabia alongside other countries. Furthermore, the purpose of this work is to demonstrate the genetic variations in the genes underlying the resistance mechanisms seen in MDR and XDR bacterial strains that have been reported in Saudi Arabia and other countries. To cover the gap, this comprehensive review explores the complex trends in antibiotic resistance and the growing risk posed by superbugs. We provide context on the concerning spread of drug-resistant bacteria by analyzing the fundamental mechanisms of antibiotic resistance and looking into individual case reports. In this article, we compiled various cases and stories associated with XDR and MDR strains from Saudi Arabia and various other countries including China, Egypt, India, Poland, Pakistan, and Taiwan. This review will serve as basis for highlighting the growing threat of MDR, XDR bacterial strains in Saudi Arabia, and poses the urgent need for national action plans, stewardship programs, preventive measures, and novel antibiotics research in the Kingdom.

Point-of-care isothermal nucleic acid amplification tests: progress and bottlenecks for extraction-free sample collection and preparation

INTRODUCTION

Suitable sample collection and preparation methods are essential to enable nucleic acid amplification testing at the point of care (POC). Strategies that allow direct isothermal nucleic acid amplification testing (iNAAT) of crude sample lysate without the need for nucleic acid extraction minimize time to result as well as the need for operator expertise and costly infrastructure.

AREAS COVERED

The authors review research to understand how sample matrix and preparation affect the design and performance of POC iNAATs. They focus on approaches where samples are directly combined with liquid reagents for preparation and amplification via iNAAT strategies. They review factors related to the type and method of sample collection, storage buffers, and lysis strategies. Finally, they discuss RNA targets and relevant regulatory considerations.

EXPERT OPINION

Limitations in sample preparation methods are a significant technical barrier preventing implementation of nucleic acid testing at the POC. The authors propose a framework for co-designing sample preparation and amplification steps for optimal performance with an extraction-free paradigm by considering a sample matrix and lytic strategy prior to an amplification assay and readout. In the next 5 years, the authors anticipate increasing priority on the co-design of sample preparation and iNAATs.

Investigation of DNA Hybridization on Nano-Structured Plasmonic Surfaces for Identifying Nasopharyngeal Viruses

Recently, studies have revealed that human herpesvirus 4 (HHV-4), also known as the Epstein-Barr virus, might be associated with the severity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Compared to SARS-CoV-2 infection alone, patients coinfected with SARS-CoV-2 and HHV-4 had higher risks of fever, inflammation, and even death, thus, confirming that HHV-4/SARS-CoV-2 coinfection in patients could benefit from clinical investigation. Although several intelligent devices can simultaneously discern multiple genes related to SARS-CoV-2, most operate via label-based detection, which restricts them from directly measuring the product. In this study, we developed a device that can replicate and detect SARS-CoV-2 and HHV-4 DNA. This device can conduct a duplex polymerase chain reaction (PCR) in a microfluidic channel and detect replicates in a non-labeled manner through a plasmonic-based sensor. Compared to traditional instruments, this device can reduce the required PCR time by 55% while yielding a similar amount of amplicon. Moreover, our device's limit of detection (LOD) reached 100 fg/mL, while prior non-labeled sensors for SARS-CoV-2 detection were in the range of ng/mL to pg/mL. Furthermore, the device can detect desired genes by extracting cells artificially infected with HHV-4/SARS-CoV-2. We expect that this device will be able to help verify HHV-4/SARS-CoV-2 coinfected patients and assist in the evaluation of practical treatment approaches.

Current and Future Advances in the Detection and Surveillance of Biosecurity-Relevant Equine Bacterial Diseases Using Loop-Mediated Isothermal Amplification (LAMP)

Horses play an important role throughout the world, whether for work, culture, or leisure, providing an ever-growing significant contribution to the economy. The increase in importation and movement of horses, both nationally and internationally, has inevitably allowed for the global equine industry to grow. Subsequently, however, the potential for transmission of fatal equine bacterial diseases has also escalated, and devasting outbreaks continue to occur. To prevent such events, disease surveillance and diagnosis must be heightened throughout the industry. Current common, or "gold-standard" techniques, have shown to be inadequate at times, thus requiring newer technology to impede outbreaks. Loop-mediated isothermal amplification (LAMP) has proven to be a reliable, rapid, and accessible tool in both diagnostics and surveillance. This review will discuss equine bacterial diseases of biosecurity relevance and their current diagnostic approaches, as well as their respective LAMP assay developments. Additionally, we will provide insight regarding newer technology and advancements associated with this technique and their potential use for the outlined diseases.

Examining Myeloperoxidase (MPO) biomarker in the saliva of patients with Lactobacillus-associated caries in Hilla City

This study aimed to evaluate the levels of myeloperoxidase (MPO) biomarkers in the saliva of individuals with Lactobacillus spp.-related caries in Hilla City. A total of 115 samples were collected, including 90 (78.26%) from patients with severe dental caries and 25 (21.74%) from healthy subjects as a control group. The age range was between 20 and 45 years, with a mean age of 33.76±2.01 for patients with severe dental caries and 24.15±0.44 for healthy subjects. Female participants constituted the majority of the study sample, with 77 (85.5%) females and 13 (14.5%) males. Pathogenic bacteria were isolated and identified using gram staining, biochemical tests, and the VITEK 2 compact system. Of the 90 clinical samples, 65 (72.2%) showed positive bacterial culture, while 25 (27.7%) samples had no bacterial growth. Lactobacillus spp. accounted for 25/65 (38.4%) of the total isolates, making it the predominant etiological agent compared to other types of bacteria, constituting 40/65 (61.5%). There was a significant decrease (p≤0.05) in myeloperoxidase levels in patients with severe dental caries and positive Lactobacillus culture compared to the control group.

Mini-thermal platform integrated with microfluidic device with on-site detection for real-time DNA amplification

The recent cases of COVID-19 have brought the prospect of and requirement for point-of-care diagnostic devices into the limelight. Despite all the advances in point-of-care devices, there is still a huge requirement for a rapid, accurate, easy-to-use, low-cost, field-deployable and miniaturized PCR assay device to amplify and detect genetic material. This work aims to develop an Internet-of-Things automated, integrated, miniaturized and cost-effective microfluidic continuous flow-based PCR device capable of on-site detection. As a proof of application, the 594-bp GAPDH gene was successfully amplified and detected on a single system. The presented mini thermal platform with an integrated microfluidic device has the potential to be used for the detection of several infectious diseases.

Promise and perils of paper-based point-of-care nucleic acid detection for endemic and pandemic pathogens

From HIV and influenza to emerging pathogens like COVID-19, each new infectious disease outbreak has highlighted the need for massively-scalable testing that can be performed outside centralized laboratory settings at the point-of-care (POC) in order to prevent, track, and monitor endemic and pandemic threats. Nucleic acid amplification tests (NAATs) are highly sensitive and can be developed and scaled within weeks while protein-based rapid tests require months for production. Combining NAATs with paper-based detection platforms are promising due to the manufacturability, scalability, and simplicity of each of these components. Typically, paper-based NAATs consist of three sequential steps: sample collection and preparation, amplification of DNA or RNA from pathogens of interest, and detection. However, these exist within a larger ecosystem of sample collection and interpretation workflow, usability, and manufacturability which can be vastly perturbed during a pandemic emergence. This review aims to explore the challenges of paper-based NAATs covering sample-to-answer procedures along with three main types of clinical samples; blood, urine, and saliva, as well as broader operational, scale up, and regulatory aspects of device development and implementation. To fill the technological gaps in paper-based NAATs, a sample-in-result-out system that incorporates the integrated sample collection, sample preparation, and integrated internal amplification control while also balancing needs of users and manufacturability upfront in the early design process is required.

Microfluidic-based blood immunoassays

Microfluidics enables the integration of whole protocols performed in a laboratory, including sample loading, reaction, extraction, and measurement steps on a single system, which offers significant advantages thanks to small-scale operation combined with precise fluid control. These include providing efficient transportation mechanisms and immobilization, reduced sample and reagent volumes, fast analysis and response times, lower power requirements, lower cost and disposability, improved portability and sensitivity, and greater integration and automation capability. Immunoassay is a specific bioanalytical method based on the interaction of antigens and antibodies, which is utilized to detect bacteria, viruses, proteins, and small molecules in several areas such as biopharmaceutical analysis, environmental analysis, food safety, and clinical diagnostics. Because of the advantages of both techniques, the combination of immunoassays and microfluidic technology is considered one of the most potential biosensor systems for blood samples. This review presents the current progress and important developments in microfluidic-based blood immunoassays. After providing several basic information about blood analysis, immunoassays, and microfluidics, the review points out in-depth information about microfluidic platforms, detection techniques, and commercial microfluidic blood immunoassay platforms. In conclusion, some thoughts and future perspectives are provided.

Ultrafast PCR Detection of COVID-19 by Using a Microfluidic Chip-Based System

With the evolution of the pandemic caused by the Coronavirus disease of 2019 (COVID-19), reverse transcriptase-polymerase chain reactions (RT-PCR) have invariably been a golden standard in clinical diagnosis. Nevertheless, the traditional polymerase chain reaction (PCR) is not feasible for field application due to its drawbacks, such as time-consuming and laboratory-based dependence. To overcome these challenges, a microchip-based ultrafast PCR system called SWM-02 was proposed to make PCR assay in a rapid, portable, and low-cost strategy. This novel platform can perform 6-sample detection per run using multiple fluorescent channels and complete an ultrafast COVID-19 RT-PCR test within 40 min. Here, we evaluated the performance of the microdevice using the gradient-diluted COVID-19 reference samples and commercial PCR kit and determined its limit-of-detection (LoD) as 500 copies/mL, whose variation coefficients for the nucleocapsid (N) gene and open reading frame 1 ab region (ORF1ab) gene are 1.427% and 0.7872%, respectively. The system also revealed an excellent linear correlation between cycle threshold (Ct) values and dilution factors (R2 > 0.99). Additionally, we successfully detected the target RNAs and internal gene in the clinical samples by fast PCR, which shows strong consistency with conventional PCR protocol. Hence, with compact dimension, user-friendly design, and fast processing time, SWM-02 has the capability of offering timely and sensitive on-site molecular diagnosis for prevention and control of pathogen transmission.

Capture, detection and purification of dsDNA amplicons using a DNA binding protein on magnetic beads

Magnetic separation has been widely exploited for capture and detection of nucleic acids, including amplicons. Streptavidin-magnetic beads (SA-MB) are typically employed for this purpose, as well as in biosensing applications. However, remaining biotinylated primer in the amplification reaction can compete with labeled amplicon for binding to the beads. Also, the harsh conditions needed for elution of bound amplicons restrict their use for purification purposes. Herein we show that a sequence-specific DNA binding protein immobilized on magnetic beads can serve as an alternative to SA-MB for these applications. This is enabled by the high binding affinity of scCro DNA binding protein for its specific sequence and its ability to bind dsDNA but not ssDNA. This specific sequence is easily incorporated in the amplicon during amplification with an extended primer. The scCro-MB exhibited higher amplicon binding capacity and detection sensitivity compared to SA-MB when both synthetic and genomic DNA were used as templates for PCR. This resulted not only from increased protein load on the beads but also from minimized interference of excess labeled primer remaining in the unpurified amplification reactions. Finally, a proof-of-concept was provided for the use of the scCro-MB for PCR amplicon purification under mild elution conditions using salt.

Progression of LAMP as a Result of the COVID-19 Pandemic: Is PCR Finally Rivaled?

Reflecting on the past three years and the coronavirus disease 19 (COVID-19) pandemic, varying global tactics offer insights into the most effective public-health responses. In the US, specifically, rapid and widespread testing was quickly prioritized to lower restrictions sooner. Essentially, only two types of COVID-19 diagnostic tests were publicly employed during the peak pandemic: the rapid antigen test and reverse transcription polymerase chain reaction (RT-PCR). However, neither test ideally suited the situation, as rapid antigen tests are far too inaccurate, and RT-PCR tests require skilled personnel and sophisticated equipment, leading to long wait times. Loop-mediated isothermal amplification (LAMP) is another exceptionally accurate nucleic acid amplification test (NAAT) that offers far quicker time to results. However, RT-LAMP COVID-19 tests have not been embraced as extensively as rapid antigen tests or RT-PCR. This review will investigate the performance of current RT-LAMP-based COVID-19 tests and summarize the reasons behind the hesitancy to embrace RT-LAMP instead of RT-PCR. We will also look at other LAMP platforms to explore possible improvements in the accuracy and portability of LAMP, which could be applied to COVID-19 diagnostics and future public-health outbreaks.

Contribution of magnetic particles in molecular diagnosis of human viruses

Viral diseases are the primary source of death, making a worldwide influence on healthcare, social, and economic development. Thus, diagnosis is the vital approach to the main aim of virus control and elimination. On the other hand, the prompt advancement of nanotechnology in the field of medicine possesses the probability of being beneficial to diagnose infections normally in labs as well as specifically. Nanoparticles are efficiently in use to make novel strategies because of permitting analysis at cellular in addition to the molecular scale. Henceforth, they assist towards pronounced progress concerning molecular analysis at the nanoscale. In recent times, magnetic nanoparticles conjugated through covalent bonds to bioanalytes for instance peptides, antibodies, nucleic acids, plus proteins are established like nanoprobes aimed at molecular recognition. These modified magnetic nanoparticles could offer a simple fast approach for extraction, purification, enrichment/concentration, besides viruses' recognition precisely also specifically. In consideration of the above, herein insight and outlook into the limitations of conventional methods and numerous roles played by magnetic nanoparticles to extract, purify, concentrate, and additionally in developing a diagnostic regime for viral outbreaks to combat viruses especially the ongoing novel coronavirus (COVID-19).

Automated Centrifugal Microfluidic Chip Integrating Pretreatment and Molecular Diagnosis for Hepatitis B Virus Genotyping from Whole Blood

Point-of-care (POC) testing for nucleic acid that combines pretreatment and molecular diagnosis is crucial in analyzing complex samples such as those encountered in clinical diagnosis. Herein, we developed a centrifugal microfluidic platform, which can achieve a series of functions including separating serum and adsorbing, washing, eluting, and detecting DNA. We combined multiple signal enhancement systems including recombinase polymerase amplification (RPA), T7 transcription technology, and clustered regularly interspaced short palindromic repeat (CRISPR) technology to yield an ultrabright signal, which can avoid false-negative results. As an application, hepatitis B virus (HBV), a virus that causes global public health problems, was successfully detected and genotyped from whole blood on the automated centrifugal microfluidic platform. Compared to the traditional diagnosis process, the POC platform largely decreased the consumption of time from 3 to 1 h and the consumption of professional labor from three persons to only one. The automated centrifugal microfluidic platform integrated pretreatment and molecular diagnosis will play an essential role in clinical detection.

Recent Advances in Solid-Phase Extraction as a Platform for Sample Preparation in Biomarker Assay

Low levels of biomarkers and the complexity of bio sample make the analytical assay of several biomarkers a challenging issue. Suitable sample preparation run remain a vital part of the puzzle of diagnostic level. Enhancing the detection limit of bioanalytical methods start during the sample preparation procedure. A robust sample preparation method is needed to evaluate the number of biomarkers. As worldwide environmental issues attract expanding consideration, all the more harmless to the ecosystem investigations are liked. Solid-phase extraction (SPE) is an appealing strategy among the sample treatment methods due to the versatility of sorbent materials, less solvent consumption, and compatibility with analytical devices. Miniaturization of the SPE gives the chance to integrate the other analytical steps in a single run, known as an easy-to-use and effective method. SPE utilizes various SPE sorbent beds such as packed beads, porous polymer monoliths, molecularly imprinted polymers, membranes, or other magnetic form microstructures to achieve high surface-to-volume ratio and appropriate chemical properties effective extraction. Also, SPE is the methodology of interest to fulfill high recovery and efficiency demands. In this review, we intend to explain more recent methods for the rational design of SPE and miniaturized SPE to determine biomarkers from biological media. The headlines are subdivided into (1) packing materials in SPE, (2) setups for sample preparation by magnetic SPE, and (3) and future perspective for the application of SPE in sample preparation for analysis of biomarkers.

A fully integrated SNP genotyping system for hereditary hearing-loss detection

Hereditary hearing loss is one of the most common human neurosensory disorders, and there is a great need for early intervention methods such as genetically screening newborns. Single nucleotide polymorphisms (SNPs) are the major genetic targets for hearing-loss screening. In this study, a fully integrated SNP genotyping system was constructed to identify hereditary hearing loss-related genetic markers from human whole blood. The entire detection process, including blood cell lysis, nucleic acid extraction, the reaction mixture distribution, the chambers sealing and the two-colour multiplex competitive allele-specific polymerase chain reaction (KASP), can be automatically conducted in a self-contained cassette within 3 hours. To critically evaluate the performance of the system, its specificity, sensitivity and stability were assessed. Then, 13 clinical samples were genotyped with this fluidic cassette system to detect seven hotspot deafness-associated mutations in three genes (MT-RNR1, GJB2 and SLC26A4). The detection results of the cassette system were 100% concordant with those obtained by Sanger sequencing, proving its accuracy in the genetic screening of inherited hearing loss.

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.

Immuno-Dipstick for Colletotrichum gloeosporioides Detection: Towards On-Farm Application

Early and quick detection of pathogens are crucial for managing the spread of infections in the biomedical, biosafety, food, and agricultural fields. While molecular diagnostics can offer the specificity and reliability in acute infectious diseases, detection of pathogens is often slowed down by the current benchtop molecular diagnoses, which are time consuming, labor intensive, and lack the mobility for application at the point-of-need. In this work, we developed a complete on-farm use detection protocol for the plant-devastating anthracnose agent: Colletotrichum gloeosporioides. Our methods combined a simplified DNA extraction on paper that is compatible with loop-mediated isothermal amplification (LAMP), coupled with paper-based immunoassay lateral flow sensing. Our results offer simple, quick, easy, and a minimally instrumented toolkit for Colletotrichum gloeosporioides detection. This scalable and adaptable platform is a valuable alternative to traditional sensing systems towards on-the-go pathogen detection in food and agriculture, biomedical, and other fields.

An internet of things-based point-of-care device for direct reverse-transcription-loop mediated isothermal amplification to identify SARS-CoV-2

Rapid and accurate testing tools for SARS-CoV-2 detection are urgently needed to prevent the spreading of the virus and to take timely governmental actions. Internet of things (IoT)-based diagnostic devices would be an ideal platform for point-of-care (POC) screening of COVID-19 and ubiquitous healthcare monitoring for patients. Herein, we present an advanced IoT-based POC device for real-time direct reverse-transcription-loop mediated isothermal amplification assay to detect SARS-CoV-2. The diagnostic system is miniaturized (10 cm [height] × 9 cm [width] × 5.5 cm [length]) and lightweight (320 g), which can be operated with a portable battery and a smartphone. Once a liquid sample was loaded into an integrated microfluidic chip, a series of sample lysis, nucleic amplification, and real-time monitoring of the fluorescent signals of amplicons were automatically performed. Four reaction chambers were patterned on the chip, targeting As1e, N, E genes and a negative control, so multiple genes of SARS-CoV-2 could be simultaneously analyzed. The fluorescence intensities in each chamber were measured by a CMOS camera upon excitation with a 488 nm LED light source. The recorded data were processed by a microprocessor inside the IoT-based POC device and transferred and displayed on the wirelessly connected smartphone in real-time. The positive results could be obtained using three primer sets of SARS-CoV-2 with a limit of detection of 2 × 10¹ genome copies/μL, and the clinical sample of SARS-CoV-2 was successfully analyzed with high sensitivity and accuracy. Our platform could provide an advanced molecular diagnostic tool to test SARS-CoV-2 anytime and anywhere.

Multiplexed detection of respiratory pathogens with a portable analyzer in a "raw-sample-in and answer-out" manner

Coronavirus disease 2019 (COVID-19) has emerged, rapidly spread and caused significant morbidity and mortality worldwide. There is an urgent public health need for rapid, sensitive, specific, and on-site diagnostic tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this study, a fully integrated and portable analyzer was developed to detect SARS-CoV-2 from swab samples based on solid-phase nucleic acid extraction and reverse transcription loop-mediated isothermal amplification (RT-LAMP). The swab can be directly inserted into a cassette for multiplexed detection of respiratory pathogens without pre-preparation. The overall detection process, including swab rinsing, magnetic bead-based nucleic acid extraction, and 8-plex real-time RT-LAMP, can be automatically performed in the cassette within 80 min. The functionality of the cassette was validated by detecting the presence of a SARS-CoV-2 pseudovirus and three other respiratory pathogens, i.e., Klebsiella pneumoniae, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. The limit of detection (LoD) for the SARS-CoV-2 pseudovirus was 2.5 copies/μL with both primer sets (N gene and ORF1ab gene), and the three bacterial species were successfully detected with an LoD of 2.5 colony-forming units (CFU)/μL in 800 μL of swab rinse. Thus, the analyzer developed in this study has the potential to rapidly detect SARS-CoV-2 and other respiratory pathogens on site in a “raw-sample-in and answer-out” manner.

A Portable Digital Loop-Mediated Isothermal Amplification Platform Based on Microgel Array and Hand-Held Reader

Digital polymerase chain reaction (dPCR) has found widespread applications in molecular diagnosis of various diseases owing to its sensitive single-molecule detection capability. However, the existing dPCR platforms rely on the auxiliary procedure to disperse DNA samples, which needs complicated operation, expensive apparatus, and consumables. Besides, the complex and costly dPCR readers also impede the applications of dPCR for point-of-care testing (POCT). Herein, we developed a portable digital loop-mediated isothermal amplification (dLAMP) platform, integrating a microscale hydrogel (microgel) array chip for sample partition, a miniaturized heater for DNA amplification, and a hand-held reader for digital readout. In the platform, the chip with thousands of isolated microgels holds the capability of self-absorption and partition of DNA samples, thus avoiding auxiliary equipment and professional personnel operations. Using the integrated dLAMP platform, λDNA templates have been quantified with a good linear detection range of 2-1000 copies/μL and a detection limit of 1 copy/μL. As a demonstration, the epidermal growth factor receptor L858R gene mutation, a crucial factor for the susceptibility of the tyrosine kinase inhibitor in non-small-cell lung cancer treatment, has been accurately identified by the dLAMP platform with a spiked plasma sample. This work shows that the developed dLAMP platform provides a low-cost, facile, and user-friendly solution for the absolute quantification of DNA, showing great potential for the POCT of nucleic acids.

Isothermal amplifications - a comprehensive review on current methods

The introduction of nucleic acid amplification techniques has revolutionized the field of medical diagnostics in the last decade. The advent of PCR catalyzed the increasing application of DNA, not just for molecular cloning but also for molecular based diagnostics. Since the introduction of PCR, a deeper understanding of molecular mechanisms and enzymes involved in DNA/RNA replication has spurred the development of novel methods devoid of temperature cycling. Isothermal amplification methods have since been introduced utilizing different mechanisms, enzymes, and conditions. The ease with which isothermal amplification methods have allowed nucleic acid amplification to be carried out has had a profound impact on the way molecular diagnostics are being designed after the turn of the millennium. With all the advantages isothermal amplification brings, the issues or complications surrounding each method are heterogeneous making it difficult to identify the best approach for an end-user. This review pays special attention to the various isothermal amplification methods by classifying them based on the mechanistic characteristics which include reaction formats, amplification information, promoter, strand break, and refolding mechanisms. We would also compare the efficiencies and usefulness of each method while highlighting the potential applications and detection methods involved. This review will serve as an overall outlook on the journey and development of isothermal amplification methods as a whole.

An Overview on Microfluidic Systems for Nucleic Acids Extraction from Human Raw Samples

Nucleic acid (NA) extraction is a basic step for genetic analysis, from scientific research to diagnostic and forensic applications. It aims at preparing samples for its application with biomolecular technologies such as isothermal and non-isothermal amplification, hybridization, electrophoresis, Sanger sequencing and next-generation sequencing. Multiple steps are involved in NA collection from raw samples, including cell separation from the rest of the specimen, cell lysis, NA isolation and release. Typically, this process needs molecular biology facilities, specialized instrumentation and labor-intensive operations. Microfluidic devices have been developed to analyze NA samples with high efficacy and sensitivity. In this context, the integration within the chip of the sample preparation phase is crucial to leverage the promise of portable, fast, user-friendly and economic point-of-care solutions. This review presents an overview of existing lab-on-a-chip (LOC) solutions designed to provide automated NA extraction from human raw biological fluids, such as whole blood, excreta (urine and feces), saliva. It mainly focuses on LOC implementation aspects, aiming to describe a detailed panorama of strategies implemented for different human raw sample preparations.

A Scalable, Easy-to-Deploy Protocol for Cas13-Based Detection of SARS-CoV-2 Genetic Material

The COVID-19 pandemic has created massive demand for widespread, distributed tools for detecting SARS-CoV-2 genetic material. The hurdles to scalable testing include reagent and instrument accessibility, availability of highly trained personnel, and large upfront investment. Here, we showcase an orthogonal pipeline we call CREST (Cas13-based, rugged, equitable, scalable testing) that addresses some of these hurdles. Specifically, CREST pairs commonplace and reliable biochemical methods (PCR) with low-cost instrumentation, without sacrificing detection sensitivity. By taking advantage of simple fluorescence visualizers, CREST allows a binary interpretation of results. CREST may provide a point-of-care solution to increase the distribution of COVID-19 surveillance.

A Scalable, Easy-to-Deploy Protocol for Cas13-Based Detection of SARS-CoV-2 Genetic Material

The COVID-19 pandemic has created massive demand for widespread, distributed tools for detecting SARS-CoV-2 genetic material. The hurdles to scalable testing include reagent and instrument accessibility, availability of highly trained personnel, and large upfront investment. Here, we showcase an orthogonal pipeline we call CREST (Cas13-based, rugged, equitable, scalable testing) that addresses some of these hurdles. Specifically, CREST pairs commonplace and reliable biochemical methods (PCR) with low-cost instrumentation, without sacrificing detection sensitivity. By taking advantage of simple fluorescence visualizers, CREST allows a binary interpretation of results. CREST may provide a point-of-care solution to increase the distribution of COVID-19 surveillance.

Fabrication Methods for Microfluidic Devices: An Overview

Microfluidic devices offer the potential to automate a wide variety of chemical and biological operations that are applicable for diagnostic and therapeutic operations with higher efficiency as well as higher repeatability and reproducibility. Polymer based microfluidic devices offer particular advantages including those of cost and biocompatibility. Here, we describe direct and replication approaches for manufacturing of polymer microfluidic devices. Replications approaches require fabrication of mould or master and we describe different methods of mould manufacture, including mechanical (micro-cutting; ultrasonic machining), energy-assisted methods (electrodischarge machining, micro-electrochemical machining, laser ablation, electron beam machining, focused ion beam (FIB) machining), traditional micro-electromechanical systems (MEMS) processes, as well as mould fabrication approaches for curved surfaces. The approaches for microfluidic device fabrications are described in terms of low volume production (casting, lamination, laser ablation, 3D printing) and high-volume production (hot embossing, injection moulding, and film or sheet operations).

Detection of Streptococcus equi subsp. equi in guttural pouch lavage samples using a loop-mediated isothermal nucleic acid amplification microfluidic device

Background

Rapid point‐of‐care (POC) detection of Streptococcus equi subsp. equi (S. equi) would theoretically reduce the spread of strangles by identifying index and carrier horses.

Hypothesis

That the eqbE isothermal amplification (LAMP) assay, and the same eqbE LAMP assay tested in a microfluidic device format, are comparable to a triplex real‐time quantitative polymerase chain reaction (qPCR) assay that is commonly used in diagnostic labs.

Samples

Sixty‐eight guttural pouch lavage (GPL) specimens from horses recovering from strangles.

Methods

Guttural pouch lavage specimens were tested for S. equi retrospectively using the benchtop eqbE LAMP, the eqbE LAMP microfluidic device, and compared to the triplex qPCR, that detects 2 S. equi‐specific genes, eqbE and SEQ2190, as the reference standard using the receiver operating characteristic area under the curve (ROC).

Results

The 27/68 specimens were positive by benchtop eqbE LAMP, 31/64 by eqbE LAMP microfluidic device, and 12/67 by triplex qPCR. Using the triplex PCR as the reference, the benchtop eqbE LAMP showed excellent discrimination (ROC Area = 0.813, 95% confidence interval [CI] = 0.711‐0.915) as did the LAMP microfluidic device (ROC Area = 0.811, 95% CI = 0.529‐0.782). There was no significant difference between the benchtop LAMP and LAMP microfluidic device (ROC Area 0.813 ± 0.055 vs 0.811 ± 0.034, P = .97).

Conclusions

The eqbE LAMP microfluidic device detected S. equi in GPL specimens from convalescent horses. This assay shows potential for development as a POC device for rapid, sensitive, accurate, and cost‐efficient detection of S. equi.

Laboratory Diagnosis of Leptospirosis

The diagnosis of leptospirosis depends on specific laboratory tests because nonspecific and diverse clinical manifestations make clinical diagnosis difficult and it is easily confused with other infectious diseases in the tropics. Suitable laboratory diagnostic tests vary depending on the stage of the disease, requiring the combination of diagnostic tests using appropriate specimens at each disease stage.

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.

A fully automated microfluidic PCR-array system for rapid detection of multiple respiratory tract infection pathogens

Rapid and accurate identification of respiratory tract infection pathogens is of utmost importance for clinical diagnosis and treatment, as well as prevention of pathogen transmission. To meet this demand, a microfluidic chip-based PCR-array system, Onestart, was developed. The Onestart system uses a microfluidic chip packaged with all the reagents required, and the waste liquid is also collected and stored on the chip. This ready-to-use system can complete the detection of 21 pathogens in a fully integrated manner, with sample lysis, nucleic acid extraction/purification, and real-time PCR sequentially implemented on the same chip. The entire analysis process is completed within 1.5 h, and the system automatically generates a test report. The lower limit-of-detection (LOD) of the Onestart assay was determined to be 1.0 × 10³ copies·mL⁻¹. The inter-batch variation of cycle threshold (Ct) values ranged from 0.08% to 0.69%, and the intra-batch variation ranged from 0.9% to 2.66%. Analytical results of the reference sample mix showed a 100% specificity of the Onestart assay. The analysis of batched clinical samples showed consistency of the Onestart assay with real-time PCR. With its ability to provide rapid, sensitive, and specific detection of respiratory tract infection pathogens, application of the Onestart system will facilitate timely clinical management of respiratory tract infections and effective prevention of pathogen transmission.

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

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

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.

Recent Trends in Nanomaterial-Based Biosensors for Point-of-Care Testing

In recent years, nanomaterials of different shape, size, and composition have been prepared and characterized, such as gold and silver nanoparticles, quantum dots, mesoporous silica nanoparticles, carbon nanomaterials, and hybrid nanocomposites. Because of their unique physical and chemical properties, these nanomaterials are increasingly used in point-of-care testing (POCT) to improve analytical performance and simplify detection process. They are used either as carriers for immobilizing biorecognition elements, or as labels for signal generation, transduction and amplification. In this commentary, we highlight recent POCT technologies that employ nanotechnology for the analysis of disease biomarkers, including small-molecule metabolites, enzymes, proteins, nucleic acids, cancer cells, and pathogens. Recent advances in lateral flow tests, printable electrochemical biosensors, and microfluidics-based devices are summarized. Existing challenges and future directions are also discussed.

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.

3D Printed Microfluidic Devices for Solid-Phase Extraction and On-Chip Fluorescent Labeling of Preterm Birth Risk Biomarkers

Solid-phase extraction (SPE) is a general preconcentration method for sample preparation that can be performed on a variety of specimens. The miniaturization of SPE within a 3D printed microfluidic device further allows for fast and simple extraction of analytes while also enabling integration of SPE with other sample preparation and separation methods. Here, we present the development and application of a reversed-phase lauryl methacrylate-based monolith, formed in 3D printed microfluidic devices, which can selectively retain peptides and proteins. The effectiveness of these SPE monoliths and 3D printed microfluidic devices was tested using a panel of nine preterm birth biomarkers of varying hydrophobicities and ranging in mass from 2 to 470 kDa. The biomarkers were selectively retained, fluorescently labeled, and eluted separately from the excess fluorescent label in 3D printed microfluidic systems. These are the first results demonstrating microfluidic analysis processes on a complete panel of preterm birth biomarkers, an important step toward developing a miniaturized, fully integrated analysis system.

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.

Smartphone-based multiplex 30-minute nucleic acid test of live virus from nasal swab extract

Rapid, sensitive and specific detection and reporting of infectious pathogens is important for patient management and epidemic surveillance. We demonstrated a point-of-care system integrated with a smartphone for detecting live virus from nasal swab media, using a panel of equine respiratory infectious diseases as a model system for corresponding human diseases such as COVID-19. Specific nucleic acid sequences of five pathogens were amplified by loop-mediated isothermal amplification on a microfluidic chip and detected at the end of reactions by the smartphone. Pathogen-spiked horse nasal swab samples were correctly diagnosed using our system, with a limit of detection comparable to that of the traditional lab-based test, polymerase chain reaction, with results achieved in ∼30 minutes.

Lab-on-a-Chip Technologies for the Single Cell Level: Separation, Analysis, and Diagnostics

In the last three decades, microfluidics and its applications have been on an exponential rise, including approaches to isolate rare cells and diagnose diseases on the single-cell level. The techniques mentioned herein have already had significant impacts in our lives, from in-the-field diagnosis of disease and parasitic infections, through home fertility tests, to uncovering the interactions between SARS-CoV-2 and their host cells. This review gives an overview of the field in general and the most notable developments of the last five years, in three parts: 1. What can we detect? 2. Which detection technologies are used in which setting? 3. How do these techniques work? Finally, this review discusses potentials, shortfalls, and an outlook on future developments, especially in respect to the funding landscape and the field-application of these chips.

Application of magnetic nanoparticles in nucleic acid detection

Nucleic acid is the main material for storing, copying, and transmitting genetic information. Gene sequencing is of great significance in DNA damage research, gene therapy, mutation analysis, bacterial infection, drug development, and clinical diagnosis. Gene detection has a wide range of applications, such as environmental, biomedical, pharmaceutical, agriculture and forensic medicine to name a few. Compared with Sanger sequencing, high-throughput sequencing technology has the advantages of larger output, high resolution, and low cost which greatly promotes the application of sequencing technology in life science research. Magnetic nanoparticles, as an important part of nanomaterials, have been widely used in various applications because of their good dispersion, high surface area, low cost, easy separation in buffer systems and signal detection. Based on the above, the application of magnetic nanoparticles in nucleic acid detection was reviewed.

Emerging Trends in Microfluidics Based Devices

One of the major challenges for scientists and engineers today is to develop technologies for the improvement of human health in both developed and developing countries. However, the need for cost-effective, high-performance diagnostic techniques is very crucial for providing accessible, affordable, and high-quality healthcare devices. In this context, microfluidic-based devices (MFDs) offer powerful platforms for automation and integration of complex tasks onto a single chip. The distinct advantage of MFDs lies in precise control of the sample quantities and flow rate of samples and reagents that enable quantification and detection of analytes with high resolution and sensitivity. With these excellent properties, microfluidics (MFs) have been used for various applications in healthcare, along with other biological and medical areas. This review focuses on the emerging demands of MFs in different fields such as biomedical diagnostics, environmental analysis, food and agriculture research, etc., in the last three or so years. It also aims to reveal new opportunities in these areas and future prospects of commercial MFDs.

A Novel Microfluidic Device Integrated with Chitosan-Modified Capillaries for Rapid ZIKV Detection

The outbreak of Zika virus (ZIKV) has posed a great challenge to public health in recent years. To address the urgent need of ZIKV RNA assays, we integrate the microfluidic chip embedded with chitosan-modified silicon dioxide capillaries, smartphone-based detection unit to be a C³-system for the rapid extraction and detection of ZIKV RNA. The C³-system is characterized by: (1) four chitosan-modified silicon dioxide capillaries integrated in the microfluidic chip for target ZIKV RNA enrichment and “in situ PCR” (polymerase chain reaction) amplification; (2) smartphone-based point of care (POC) device consisting of a pneumatic subsystem for controlling the nucleic acid extraction processes in the microfluidic chip, a heating subsystem for sample lysis and PCR amplification, and an optical subsystem for signal acquisition. The entire detection processes including sample lysis, ZIKV RNA enrichment, and reverse-transcription polymerase chain reaction (RT-PCR) is achieved in the microfluidic chip. Moreover, PCR buffers can be directly loaded into the chitosan-modified silicon dioxide capillaries for “in situ PCR”, in which the captured ZIKV RNA is directly used for downstream PCR without any loss. ZIKV RNA extracted by the C³-system can be successfully recovered at very low concentrations of 50 transducing units (TU)/mL from crude human saliva. This means that our method of detecting viremia in patients infected with ZIKV is reliable.

An integrated biosensor platform for extraction and detection of nucleic acids

The development of portable systems for analysis of nucleic acids (NAs) is crucial for the evolution of biosensing in the context of future healthcare technologies. The integration of NA extraction, purification, and detection modules, properly actuated by microfluidics technologies, is a key point for the development of portable diagnostic systems. In this paper, we describe an integrated biosensor platform based on a silicon-plastic hybrid lab-on-disk technology capable of managing NA extraction, purification, and detection processes in an integrated format. The sample preparation process is performed by solid-phase extraction technology using magnetic beads on a plastic disk, while detection is done through quantitative real-time polymerase chain reaction (qRT-PCR) on a miniaturized silicon device. The movement of sample and reagents is actuated by a centrifugal force induced by a disk actuator instrument. The assessment of the NA extraction and detection performance has been carried out by using hepatitis B virus (HBV) DNA genome as a biological target. The quantification of the qRT-PCR chip in the hybrid disk showed an improvement in sensitivity with respect to the qRT-PCR commercial platforms, which means an optimization of time and cost. Limit of detection and limit of quantification values of about 8 cps/reaction and 26 cps/reaction, respectively, were found by using analytical samples (synthetic clone), while the results with real samples (serum with spiked HBV genome) indicate that the system performs as well as the standard methods.

Enhanced sample filling and discretization in thermoplastic 2D microwell arrays using asymmetric contact angles

Sample filling and discretization within thermoplastic 2D microwell arrays is investigated toward the development of low cost disposable microfluidics for passive sample discretization. By using a high level of contact angle asymmetry between the filling channel and microwell surfaces, a significant increase in the range of well geometries that can be successfully filled is revealed. The performance of various array designs is characterized numerically and experimentally to assess the impact of contact angle asymmetry and device geometry on sample filling and discretization, resulting in guidelines to ensure robust microwell filling and sample isolation over a wide range of well dimensions. Using the developed design rules, reliable and bubble-free sample filling and discretization is achieved in designs with critical dimensions ranging from 20 μm to 800 μm. The resulting devices are demonstrated for discretized nucleic acid amplification by performing loop-mediated isothermal amplification for the detection of the mecA gene associated with methicillin-resistant Staphylococcus aureus.

A self-contained and fully integrated fluidic cassette system for multiplex nucleic acid detection of bacteriuria

The gold standard for diagnosing infectious diseases is culture-based identification of bacterial pathogens, which is time-consuming and labour-intensive. Current advances in molecular diagnostics and microfluidic technologies have made the rapid detection of bacteria or viruses in clinical specimens possible. However, the need for rapid, sensitive and multiplex detection of pathogens in a "sample-in and answer-out" manner has not been fully satisfied. In this study, a self-contained and fully integrated fluidic cassette and its supporting analyser were constructed for multiplex detection of bacteria to accelerate the diagnosis of urinary tract infections (UTIs). The fully integrated cassette contains all the necessary components and reagents for bacterial analysis. All of the bacterial analysis processes, including bacterial lysis, magnetic silica bead-based DNA extraction, DNA elution and multiplex loop-mediated amplification (LAMP), are automatically conducted in the cassette. This cassette was successfully applied for the detection of four major pathogenic bacteria in UTIs, i.e., Escherichia coli, Proteus mirabilis, Salmonella typhimurium and Staphylococcus aureus. The first three were successfully detected with a limit of detection (LoD) of 1 colony-forming unit (CFU) μL^-1 and the last was with a LoD of 10 CFU μL^-1 in urine samples, demonstrating that the cassette has similar sensitivity compared to that of the manual protocol, which is lower than that required by UTIs. The turnaround time for this cassette-based sample-to-answer system was approximately 100 minutes, and the detection is sensitive, fully automated, and accurate, demonstrating the potential to be a useful diagnostic tool for UTIs.