Microfluidic-assisted integrated nucleic acid test strips for POCT

Development and optimization of an antibody-free nucleic acid lateral flow assay (AF-NALFA) as part of a molecular toolkit for visual readout of amplified Listeria monocytogenes DNA

Listeria monocytogenes is a Gram-positive foodborne pathogen responsible for listeriosis, a severe disease with high mortality in immunocompromised individuals. Rapid and accurate detection in food samples is essential for food safety. In this study, we developed and optimized an Antibody-Free Nucleic Acid Lateral Flow Assay (AF-NALFA) as part of a molecular detection toolkit for the visual readout of amplified L. monocytogenes hlyA gene, in combination with ultra-fast asymmetric PCR (aPCR) and oligonucleotide probe hybridization. Three critical parameters were optimized: oligonucleotide probe concentration on test and control lines, gold nanoparticle-probe conjugation ratio, and running buffer composition. In pure bacterial cultures, the limit of detection (LOD) of AF-NALFA was 12.62 copies for L. monocytogenes ATCC 7644, 8.68 copies for ATCC 19117, and 4.83 copies for ATCC 13932. These values were quantitatively assessed using qPCR, confirming the assay's consistency in detecting low DNA copy numbers. The prototype demonstrated 100% specificity against 13 other bacterial species. Furthermore, it was successfully tested in artificially contaminated UHT milk after 1 year of storage at room temperature, detecting L. monocytogenes at 1-30 CFU/mL without DNA purification or selective enrichment. The AF-NALFA enabled visual detection of target ssDNA hybridization within 20 min, offering a rapid, cost-effective alternative to DNA detection methods requiring expensive equipment, specialized expertise, and time-consuming procedures. These findings highlight AF-NALFA's potential as a complementary tool for L. monocytogenes surveillance, providing a practical solution for rapid screening in food safety laboratories and epidemiological monitoring.

Handheld RPA-based molecular POCT system for rapid, low-cost 8-plexed detection of respiratory pathogens at home

During seasonal influenza or emerging respiratory outbreaks, rapid home-based multiplex molecular point-of-care testing (POCT) for respiratory pathogens is crucial for early diagnosis and intervention, particularly in vulnerable populations. However, existing POCT systems, primarily designed for clinical settings, are often too complex, costly, and reliant on trained operators, limiting their suitability for home use. To overcome these barriers, we introduce a microfluidic cartridge-based system leveraging recombinase polymerase amplification (RPA) for multiplexed detection of respiratory pathogens in home environments. The microfluidic cartridge is designed with three parallel channels-each integrating a lysis chamber, an RPA chamber preloaded with lyophilized reagents, and an air storage chamber. Each detection channel enables extraction-free, single-channel 3-plex RPA assays, and by combining three-channel parallel detection, the system achieves simultaneous identification of eight respiratory pathogens and one internal control in under 25 min. A novel pneumatic pressure pumping strategy ensures precise flow control through dynamic bladder compression, paired with microchannel hydraulic resistance matching to guarantee uniform volumetric distribution and synchronized flow across all channels. Furthermore, a dynamic mixing method promotes homogeneous mixing of RPA reagents with lysed samples via a bidirectional flow between the lysis and RPA chambers, enhancing assay reliability. Our microfluidic design enables significant miniaturization, yielding a compact, lightweight system (<1 kg) suitable for handheld or desktop use. Its low power consumption (3 W) and remarkable cost-effectiveness ($1.4 per test) enhance the system's practicality and accessibility for home settings. Validation with 356 nasopharyngeal swabs further confirms its robust performance, achieving high sensitivity (>97%) and specificity (>99%), ensuring reliable at-home diagnosis of respiratory co-infections without requiring professional operation.

The Development Potential of AuNPs-Based Lateral Flow Technology Combined with Other Advanced Technologies in POCT

Currently, there is a demand for rapid, sensitive, low-cost, portable, and visualized testing technologies for point-of-care testing (POCT). However, most traditional testing methods face challenges such as long testing times, complicated operations, and high costs, limiting their implementation in resource-limited areas and hindering the fulfillment of POCT demands. Lateral flow assay (LFA) has emerged as an ideal detection technique for POCT, particularly when utilizing gold nanoparticles (AuNPs) as labels. This approach not only enables visualization with the naked eye but also reduces the need for expensive reading instruments. The technologies reviewed in this paper encompass integrated detection technology utilizing amplification technique and LFA, integrated detection technology utilizing clustered regularly interspaced short palindromic repeats (CRISPR) system and LFA, the utilization of surface-enhanced Raman spectroscopy (SERS) in LFA detection technique, the utilization of aptamers in LFA detection technique, and the utilization of DNA barcodes in LFA detection technique. By integrating these advanced techniques, there is significant potential to overcome the limitations of LFA, including low sensitivity, poor specificity, inability to quantify, and false positives, thereby enabling broader applications in resource-constrained settings. Additionally, this article comprehensively evaluates the strengths and weaknesses of each approach, underscoring the immense developmental potential of AuNPs-based LFA in point-of-care testing (POCT).

Fluorescence excitation-emission matrix spectroscopy combined with machine learning for the classification of viruses for respiratory infections

Significant efforts were currently being made worldwide to develop a tool capable of distinguishing between various harmful viruses through simple analysis. In this study, we utilized fluorescence excitation-emission matrix (EEM) spectroscopy as a rapid and specific tool with high sensitivity, employing a straightforward methodological approach to identify spectral differences between samples of respiratory infection viruses. To achieve this goal, the fluorescence EEM spectral data from eight virus samples was divided into training and test sets, which were then analyzed using random forest and support vector machine classification models. We proposed a novel strategy for data fusion based on fast Fourier transform (FFT) and wavelet transform (WT) methods, which significantly enhanced classification accuracy from 45 % to 75 %. This approach improved the classification capability for similar spectral characteristics of viruses. Rhinovirus was further differentiated from rotavirus, while influenza A virus was distinguished from inactivated poliovirus vaccines and rhinovirus. This study demonstrated that the integration of fluorescence EEM spectroscopy with machine learning algorithms presented significant potential for the detection of unidentified harmful substances in the ambient environment.

A comprehensive scoping review of methodological approaches and clinical applications of tear fluid biomarkers

Tear fluid is an emerging source of disease biomarkers, drawing attention due to its quick, inexpensive, and non-invasive collection. The advancements in detection techniques enable the measurement of ultra-low biomarker levels from small sample volumes typical of tear fluid. The lack of standardized protocols for collection, processing, and analysis of tear fluid remains a significant challenge. To address this, we convened the Tear Research Network Review Taskforce in 2022 to review protocols from the past three decades, providing a comprehensive overview of the methodologies used in tear fluid biomarker research. A total of 1484 articles published from January 1974 to May 2024 from two electronic databases, Embase and Ovid MEDLINE, were reviewed. An exponential increase in the number of articles on tear fluid biomarkers was observed from 2015 onwards. The two most commonly reported collection methods were; glass capillaries (45.2%), and Schirmer's strips (25%), with glass capillary tube collection remaining the most frequent method until 2019, when Schirmer's strips became the leading method. Most articles analyzed tear fluid proteins (65%) and focused on a single analyte (32.3%). In recent years, an increase was observed in the type and number of examined analytes. The differences in the reported methodologies and protocols underscore the need for standardization and harmonization within the field of tear fluid biomarkers to minimize methodological differences and reduce variability in clinical outcomes. Consistent and detailed reporting is essential for improving the reproducibility and validity of tear fluid studies, in order to advance their potential clinical applications.

Advancing clinical biochemistry: addressing gaps and driving future innovations

Modern healthcare depends fundamentally on clinical biochemistry for disease diagnosis and therapeutic guidance. The discipline encounters operational constraints, including sampling inefficiencies, precision limitations, and expansion difficulties. Recent advancements in established technologies, such as mass spectrometry and the development of high-throughput screening and point-of-care technologies, are revolutionizing the industry. Modern biosensor technology and wearable monitors facilitate continuous health tracking, Artificial Intelligence (AI)/machine learning (ML) applications enhance analytical capabilities, generating predictive insights for individualized treatment protocols. However, concerns regarding algorithmic bias, data privacy, lack of transparency in decision-making ("black box" models), and over-reliance on automated systems pose significant challenges that must be addressed for responsible AI integration. However, significant limitations remain-substantial implementation expenses, system incompatibility issues, and information security vulnerabilities intersect with ethical considerations regarding algorithmic fairness and protected health information. Addressing these challenges demands coordinated efforts between clinicians, scientists, and technical specialists. This review discusses current challenges in clinical biochemistry, explicitly addressing the limitations of reference intervals and barriers to implementing innovative biomarkers in medical settings. The discussion evaluates how advanced technologies and multidisciplinary collaboration can overcome these constraints while identifying research priorities to enhance diagnostic precision and accessibility for better healthcare delivery.

Integrated and streamlined microfluidic device for molecular diagnosis of pathogen through direct PCR amplification

Background

Polymerase chain reaction (PCR) is a gold-standard method widely acknowledged for offering precise and rapid analysis of genetic material, particularly having a crucial role in detecting pathogens and diagnosing infectious diseases. However, the complexity of the PCR process (including nucleic acid extraction/purification, amplification, and amplicon detection) hinders its widespread adoption in point-of-care testing, where simplicity and rapidity are essential for practical use.

Results

In this study, we developed a microfluidic genetic analysis device that leverages direct PCR technology to simplify the entire PCR process, focusing on enhancing the usability and accessibility of the device for point-of-care diagnostics. Direct PCR, which enables direct DNA amplification from biological samples without the need for DNA extraction and purification, streamlines the device architecture and transforms it into a more user-friendly form. Within the device, two spatially separated zones for PCR and micro-capillary electrophoresis (μCE) are sequentially connected via a microchamber plate, which is slidable on top of the device and transfers the amplified products from the PCR zone to the μCE zone for subsequent analysis. Using our device, we quantitatively analyzed two types of bacteria-Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus)-in milk (food poisoning simulation) with a sensitivity of up to 10 bacterial cells.

Significance

Considering how prominent PCR is for diagnostics, this work represents the potential to make traditionally labor-intensive molecular assays available in a decentralized point-of-care setting.

Innovations in one-step point-of-care testing within microfluidics and lateral flow assays for shaping the future of healthcare

Point-of-care testing (POCT) technology, using lateral flow assays and microfluidic systems, facilitates cost-effective diagnosis, timely treatment, ongoing monitoring, and prevention of life-threatening outcomes. Aside from significant advancements demonstrated in academic research, implementation in real-world applications remains frustratingly limited. The divergence between academic developments and practical utility is often due to factors such as operational complexity, low sensitivity and the need for trained personnel. Taking this into consideration, our objective is to present a critical and objective overview of the latest advancements in fully integrated one-step POCT assays for home-testing which would be commercially viable. In particular, aspects of signal amplification, assay design modification, and sample preparation are critically evaluated and their features and medical applications along with future perspective and challenges with respect to minimal user intervention are summarized. Associated with and very important for the one-step POCT realization are also readout devices and fabrication processes. Critical analysis of available and useful technologies are presented in the SI section.

Engineering Stimuli-Responsive Materials for Precision Medicine

Over the past decade, precision medicine has garnered increasing attention, making significant strides in discovering new therapeutic drugs and mechanisms, resulting in notable achievements in symptom alleviation, pain reduction, and extended survival rates. However, the limited target specificity of primary drugs and inter-individual differences have often necessitated high-dosage strategies, leading to challenges such as restricted deep tissue penetration rates and systemic side effects. Material science advancements present a promising avenue for these issues. By leveraging the distinct internal features of diseased regions and the application of specific external stimuli, responsive materials can be tailored to achieve targeted delivery, controllable release, and specific biochemical reactions. This review aims to highlight the latest advancements in stimuli-responsive materials and their potential in precision medicine. Initially, we introduce disease-related internal stimuli and capable external stimuli, elucidating the reaction principles of responsive functional groups. Subsequently, we provide a detailed analysis of representative pre-clinical achievements of stimuli responsive materials across various clinical applications, including enhancements in the treatment of cancers, injury diseases, inflammatory diseases, infection diseases, and high-throughput microfluidic biosensors. Finally, we discuss some clinical challenges, such as off-target effects, long-term impacts of nano-materials, potential ethical concerns, and offer insights into future perspectives of stimuli-responsive materials.

Rapid Fluid Velocity Field Prediction in Microfluidic Mixers via Nine Grid Network Model

The rapid advancement of artificial intelligence is transforming the computer-aided design of microfluidic chips. As a key component, microfluidic mixers are widely used in bioengineering, chemical experiments, and medical diagnostics due to their efficient mixing capabilities. Traditionally, the simulation of these mixers relies on the finite element method (FEM), which, although effective, presents challenges due to its computational complexity and time-consuming nature. To address this, we propose a nine-grid network (NGN) model theory with a centrally symmetric structure.The NGN uses a symmetric structure similar to a 3 × 3 grid to partition the fluid space to be predicted. Using this theory, we developed and trained an artificial neural network (ANN) to predict the fluid dynamics within microfluidic mixers. This approach significantly reduces the time required for fluid evaluation. In this study, we designed a prototype microfluidic mixer and validated the reliability of our method by comparing it with predictions from traditional FEM software. The results show that our NGN model completes fluid predictions in just 40 s compared to approximately 10 min with FEM, with acceptable error margins. This technology achieves a 15-fold acceleration, greatly reducing the time and cost of microfluidic chip design.

Application of recombinase polymerase amplification with lateral flow assay to pathogen point-of-care diagnosis

Since the outbreak of the new coronavirus, point-of-care diagnostics based on nucleic acid testing have become a requirement for the development of pathogen diagnostics, which require the ability to accurately, rapidly, and conveniently detect pathogens. Conventional nucleic acid amplification techniques no longer meet the requirements for pathogen detection in low-resource, low-skill environments because they require specialist equipment, complex operations, and long detection times. Therefore, recombinant polymerase amplification (RPA) is becoming an increasingly important method in today's nucleic acid detection technology because it can amplify nucleic acids in 20-30 minutes at a constant temperature, greatly reducing the dependence on specialist equipment and technicians. RPA products are primarily detected through methods such as real-time fluorescence, gel electrophoresis, lateral flow assays (LFAs), and other techniques. Among these, LFAs allow for the rapid detection of amplification products within minutes through the visualization of results, offering convenient operation and low cost. Therefore, the combination of RPA with LFA technology has significant advantages and holds broad application prospects in point-of-care (POC) diagnostics, particularly in low-resource settings. Here, we focus on the principles of RPA combined with LFAs, their application to pathogen diagnosis, their main advantages and limitations, and some improvements in the methods.

Proposal of a Rapid Detection System Using Image Analysis for ELISA with an Autonomous Centrifugal Microfluidic System

In this study, with the aim of adapting an enzyme-linked immunosorbent assay (ELISA) system for point-of-care testing (POCT), we propose an image analysis method for ELISAs using a centrifugal microfluidic device that automatically executes the assay. The developed image analysis method can be used to quantify the color development reaction on a TMB (3,3',5,5'-tetramethylbenzidine) substrate. In a conventional ELISA, reaction stopping reagents are required at the end of the TMB reaction. In contrast, the developed image analysis method can analyze color in the color-developing reaction without a reaction stopping reagent. This contributes to a reduction in total assay time. The microfluidic devices used in this study could execute reagent control for ELISAs by steady rotation. In the demonstration of the assay and image analysis, a calibration curve for mouse IgG detection was successfully prepared, and it was confirmed that the image analysis method had the same performance as the conventional analysis method. Moreover, the changes in the amount of color over time confirmed that a calibration curve equal to the endpoint analysis was obtained within 2 min from the start of the TMB reaction. As the assay time before the TMB reaction was approximately 7.5 min, the developed ELISA system could detect TMB in just 10 min. In conventional methods using a plate reader, the assay required a time of 90 min for manual handling using microwell plates, and in the case of using automatic microfluidic devices, 30 min were required. The time of 10 min realized by this proposed method is equal to the time required for detection in an immunochromatographic assay with a lateral flow assay; therefore, it is expected that ELISAs can be performed sufficiently to adapt to POCT.

Dual lateral flow assay based on PdRu nanocages for human Papillomavirus detection

Cervical cancer is one of the most common gynecological malignancies, with the vast majority of which being caused by persistent infection with Human Papillomavirus (HPV) 16 and 18. The current available HPV detection methods are sensitive and genotyped but are restricted by expensive instruments and skilled personnel. The development of an easy-to-use, rapid, and cost-friendly analysis method for HPV is of great need. Herein, hollow palladium-ruthenium nanocages modified with two oligonucleotides (PdRu capture probes) were constructed for genotyping and simultaneous detection of target nucleic acids HPV16 and HPV18 by dual lateral flow assay (DLFA). PdRu capture probes were endowed with bi-functions for the first time, which could be used to output signals and hybridize target nucleic acids. Under optimized conditions, the PdRu based-DLFA with detection limits of 0.93 nM and 0.19 nM, respectively, exhibited convenient operation, and high sensitivity. Meanwhile, the DLFA achieved excellent rapid detection within 20 min, which was attributed to capture probes that can be directly bound to amplification-free target nucleic acids. Therefore, the development of PdRu-based DLFA can be utilized for rapid, sensitive, and simultaneous genotyping detection of HPV16 and HPV18, showing great application for nucleic acid detection.

Developing portable and controllable fluorescence capillary imprinted sensor for visual detection Crohn's disease biomarkers

Simultaneous detection of multiple biomarker levels is essential to improve the accuracy of early diagnosis. Introducing capillary will simplify procedure, less time, and reduce reagent consumption for point-of-care testing of biomarkers. Here, we developed a portable and controllable smartphone-integrated fluorescence capillary imprinted sensing platform for the accuracy visual detection of Crohn's disease biomarkers (lysozyme, Fe3+) using single-excitation/double-signal detection. A novel controllable capillary coating strategy was developed by static gas-driven coating method for synthesis uniform fluorescence capillary imprinted sensor (Si-CD/g-CdTe@MIP capillary sensor). When Fe3+ and lysozyme were added, the fluorescence intensity of Si-CD/g-CdTe@MIP capillary sensor was quenched at 426 nm and enhanced at 546 nm, respectively. This Si-CD/g-CdTe@MIP capillary sensor has high sensitivity and selectivity for quantification lysozyme and Fe3+ simultaneously with the detection limit of 0.098 nM and 0.20 nM, respectively. In addition, the smartphone-integrated Si-CD/g-CdTe@MIP capillary sensor was applied for the intelligent detection of lysozyme and Fe3+, in which the detection limit was calculated as 0.32 nM and 0.65 nM. The smartphone-integrated visual Si-CD/g-CdTe@MIP capillary sensor realized ultrasensitive microanalysis (18 μL/time) of biomarkers in health man and Crohn 's patients, providing a novel strategy for early diagnosis of Crohn 's disease.

Decentralized food safety and authentication on cellulose paper-based analytical platform: A review

Food safety and authenticity analysis play a pivotal role in guaranteeing food quality, safeguarding public health, and upholding consumer trust. In recent years, significant social progress has presented fresh challenges in the realm of food analysis, underscoring the imperative requirement to devise innovative and expedient approaches for conducting on-site assessments. Consequently, cellulose paper-based devices (PADs) have come into the spotlight due to their characteristics of microchannels and inherent capillary action. This review summarizes the recent advances in cellulose PADs in various food products, comprising various fabrication strategies, detection methods such as mass spectrometry and multi-mode detection, sampling and processing considerations, as well as applications in screening food safety factors and assessing food authenticity developed in the past 3 years. According to the above studies, cellulose PADs face challenges such as limited sample processing, inadequate multiplexing capabilities, and the requirement for workflow integration, while emerging innovations, comprising the use of simplified sample pretreatment techniques, the integration of advanced nanomaterials, and advanced instruments such as portable mass spectrometer and the innovation of multimodal detection methods, offer potential solutions and are highlighted as promising directions. This review underscores the significant potential of cellulose PADs in facilitating decentralized, cost-effective, and simplified testing methodologies to maintain food safety standards. With the progression of interdisciplinary research, cellulose PADs are expected to become essential platforms for on-site food safety and authentication analysis, thereby significantly enhancing global food safety for consumers.

All-in-one detection of breast cancer-derived exosomal miRNA on a pen-based paper chip

Exosomal microRNAs (miRNAs) play a pivotal role in intercellular communication, regulating gene expression in target cells, and hold significant promise as cancer biomarkers for early detection and screening. However, achieving precise and viable detection of exosomal miRNAs remains a challenge. This paper proposes an all-in-one detection strategy for breast cancer-derived exosomal miRNA-21 on a pen-based paper chip (PPC). The PPC is constructed using a modified automatic pen and lateral flow assay (LFA), which results in a cost-effective fabrication process. The user only needs to add the sample and trigger the top of the self-contained PPC after a period of time to complete the entire detection process. To enhance the sensitivity of exosomal miRNA testing, an enzyme-free catalyzed hairpin assembly (CHA) is further introduced, enabling highly sensitive detection of miRNA-21 with a limit of detection (LOD) of 25 fmol. Additionally, the detection of miRNAs in differentially-expressed cells and clinical samples has also been successfully achieved with high specificity. Overall, the proposed PPC provides an effective tool for detecting early cancer, monitoring diseases, and establishing point of care testing (POCT).