Microfluidic space coding for multiplexed nucleic acid detection via CRISPR-Cas12a and recombinase polymerase amplification

Space-coded microchip for multiplexed respiratory virus detection via CRISPR-Cas12a and RPA

Multiple infections of respiratory viruses are common in patients with clinical respiratory diseases, but current detection methods still have problems such as complex equipment and long detection time. Rapid, low-cost, and on-site detection of human respiratory viruses is crucial for both clinical diagnosis and population screening. In this research, we created a space-coded microfluidic chip (SC-Chip) for the recognition of nine respiratory viruses: influenza A virus, influenza B virus, severe acute respiratory syndrome coronavirus 2, human coronavirus OC43, human coronavirus NL63, human coronavirus HKU1, human respiratory syncytial virus, human parainfluenza virus, and human metapneumovirus. For the first time, a comprehensive sequence comparison among these viruses was performed to design the recombinase polymerase amplification (RPA) primers and Cas12a-crRNAs. The SC-Chip partitions samples amplified by RPA into spatially coded wells preloaded with CRISPR-Cas12a detection reagents, enabling the identification of all nine viral targets in a single test using a single fluorescence probe. The chip-based assay displays 9 respiratory viruses in less than 40 min with a minimum detection limit at a concentration of 10-18 M (∼1 copy/reaction). Additionally, the efficacy of the method was assessed through its application to 35 clinical patient samples identified as being at risk for respiratory virus infection, yielding a sensitivity of 90 % and a specificity of 100 %. In summary, this space-coded microfluidic CRISPR system offers several advantages, including ease of operation, cost-effectiveness, and rapid data acquisition, thereby holding great potential for multiplexed detection of nucleic acid targets in a clinical setting.

An ultra-sensitive, multiplexed, and cost-effective POCT system for the detection of co-infecting respiratory viruses, including SARS-CoV-2, Flu A, Flu B, and RSV, within 30 min

The co-circulation of respiratory viruses, including SARS-CoV-2, Influenza A (Flu A), Influenza B (Flu B), and respiratory syncytial virus (RSV), poses a significant public health threat. Timely recognition of these viruses allows healthcare professionals to implement effective infection control measures, allocate medical resources properly, and prevent complications from incorrect treatments. Multiplex nucleic acid testing Point-of-care test (mNAT-POCT) circumvents issues of traditional tests, such as high demands on laboratory environments, personnel, and equipment, and limited target analyses, allowing its use in point-of-care settings. However, challenges include primer-primer interactions during fast amplification, high automation requirements, configuring multiple fluorescence channels to avoid spectral overlap, and balancing rapid thermal cycling with sensitive fluorescence signal collection. To address these issues, we developed the multiplexed reverse transcription-quantitative PCR (RT-qPCR) POCT system iNAT SARS-CoV-2/Flu A/Flu B/RSV Assay. This assay enables quick, automatic, and accurate detection of multiple pathogens, improving diagnostic and treatment efficiency for syndromic infectious diseases. The limit of detection (LoD) is 45 copies/mL for SARS-CoV-2, 133 copies/mL for Flu A, 57 copies/mL for Flu B, and 212.5 copies/mL for RSV, with a turnaround time (TAT) of 30 min. Clinical sample analysis showed a 99.36 % agreement with National Medical Products Administration (NMPA) approved reference tests. In conclusion, the iNAT SARS-CoV-2/Flu A/Flu B/RSV Assay performs excellently in detecting and differentiating SARS-CoV-2, Flu A, Flu B, and RSV in respiratory infections, which is crucial for accurate diagnoses.

A rapid and ultrasensitive RPA-assisted CRISPR-Cas12a/Cas13a nucleic acid diagnostic platform with a smartphone-based portable device

The spread of infectious diseases can be controlled by early identification of the source of infection and timely diagnosis to stop transmission. Real-time fluorescence quantitative polymerase chain reaction (PCR) is the current gold standard for pathogen diagnosis, with high detection sensitivity and accuracy. However, due to the need for specialized equipment, laboratories, and personnel, it is difficult to achieve rapid and immediate diagnosis during large-scale infectious disease outbreaks. Herein, an optimized CRISPR-based nucleic acid detection method was developed that reduces the CRISPR detection time to 15 min while maintaining high sensitivity. By using nucleic acid extraction-free and lyophilization techniques, the 'sample-in-result-out' detection of the two target genes of SARS-CoV-2, the human internal reference gene, and the negative quality control sample can be completed in 20 min, with a sensitivity of 0.5 copies/μL. Additionally, to facilitate the application, a smartphone-based reverse transcription-recombinase polymerase amplification (RT-RPA)-assisted CRISPR-rapid, portable nucleic acid detection device was developed, integrating functions such as heating, centrifugation, mixing, optical detection and result output. Process control, output, and uploading of detection results were conducted through smartphones. The device is not dependent on a power supply and can perform on-site rapid virus detection in resource-limited settings. Real-time uploading of results helps to rapidly implement epidemic prevention and control measures, providing an innovative means of detection, control, and prevention of virus-based infectious diseases. This important work provides a new and effective tool to manage potential future outbreaks of infectious diseases.

CRISPR/Cas12a-based transition state molecular switch for low-background detection of HPV-16 on a microfluidic platform

Human papillomavirus type 16 (HPV-16) is a high-risk oncogenic subtype of HPV, strongly associated with the pathogenesis of multiple cancers. Researchers have developed many detection methods for HPV-16, among which, the detection method based on microfluidic has the characteristics of high efficiency and high sensitivity. However, non-specific adsorption remains a critical challenge, often leading to elevated background signals. Here, we propose an On-Chip assay integrated by transition state molecular switch based on CRISPR-Cas12a (OCTMS-CRISPR) for stable, sensitive, and low-background fluorescence detection of HPV-16. This system leverages a highly integrated molecular switch and Cas12a to perform dual-screening, while the dissociation products of the molecular switch activate trans-cleavage activity. Our data suggest that OCTMS-CRISPR suppresses background signals on microfluidic chip while maintaining the specificity and sensitivity of trans-cleavage. For demonstration, we detected five HPV subtypes and base mismatches at varying positions and quantities. The LOD can reach 7.64 pM (average fluorescence intensity) and 9.91fM (pixel counting), showing great potential in the field of biosensing and DNA chips.

Advancements in fluorescent nanobiosensors for HPV detection: from integrating nanomaterials to DNA nanotechnology

Human papillomavirus (HPV) is a leading cause of cervical cancer and other malignancies, necessitating the development of highly sensitive and specific detection tools. This review explores recent advancements in fluorescent nanobiosensors (FNBS) for HPV detection, focusing on the integration of nanomaterials and DNA nanotechnology, highlighting their contributions to improving sensitivity, specificity, and point-of-care (POC) usability. The review critically evaluates a range of nanomaterial-based FNBS, including those employing quantum and carbon dots, nanoclusters, nanosheets, and nanoparticles, discussing their underlying signal amplification mechanisms, target recognition strategies, and limitations related to toxicity, stability, and reproducibility. Furthermore, it examines the application of diverse DNA nanotechnology, such as DNA origami, DNAzyme, catalytic hairpin assembly (CHA), hybridization chain reaction (HCR), and DNA hydrogel in improving FNBS performance. It also addresses the current challenges in clinical translation, emphasizing the necessity for large-scale production methods and thorough clinical validation to ensure biosafety. It also outlines the potential of innovative technologies, such as CRISPR-Cas-based diagnostics and artificial intelligence, to further revolutionize HPV detection and enable accessible, cost-effective screening, particularly in resource-limited settings. This review provides a valuable resource for researchers and clinicians seeking to develop next-generation FNBS for improved HPV diagnostics and cervical cancer prevention.

CRISPR/Cas Multiplexed Biosensing: Advances, Challenges, and Perspectives

Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) protein systems are renowned for their high sensitivity and specificity, enabling them as a powerful diagnostic toolbox. Multiplexed detection of panels of targets, as opposed to single targets, is imperative for reliable and conclusive disease diagnostics. However, multiplex application of the CRISPR/Cas system has long been hindered by indistinguishable signals from specific targets due to nonspecific chaotic trans-cleavage. To make a breakthrough, substantial efforts have been devoted to CRISPR/Cas-powered multiplexed biosensing strategies, which consequently experienced rapid development over the past five years. This review systematically summarizes recent advances in CRISPR/Cas multiplexed detection encompassing Cas9, Cas12, and Cas13. Key focus issues include multiplex biosensing strategies and their respective advantages and limitations, sensing mechanisms, and detection performance of novel validated examples. Finally, the status and challenges of CRISPR/Cas multiplexed biosensing are critically discussed, and future outlooks are proposed for their potential practical application. This Perspective aims to inspire significant research and promote the development of the next generation of CRISPR/Cas multiplexed biosensing.

Microfluidics-Based High-Throughput Single-Cell Analysis of Reactive Oxygen Species and T Cell Exhaustion

Reactive oxygen species (ROS) play a significant role in cellular signaling and oxidative stress, with elevated levels often linked to T cell exhaustion in various pathological conditions, including cancer. However, the relationship between ROS and T cell exhaustion in acute myeloid leukemia (AML) remains unexplored. To address this, we developed a high-throughput single-cell platform─T cell exhaustion and reactive oxygen species analyzer (TEROSA). The system achieved a single-cell capture efficiency of up to 80% with a throughput of 2400 cells and enabled dynamic monitoring of triple molecules, including the intracellular mitochondrial superoxide, on-membrane T cell exhaustion marker PD-1, and secreted extracellular H2O2. Our study evaluated the device's performance across multiple cell lines and demonstrated its capability to assess ROS production at the single-cell level. In particular, we analyzed T cells from AML patients and found significantly elevated ROS levels and increased PD-1 expression compared to healthy donors, suggesting a potential link between ROS and T cell exhaustion in AML. These findings highlight the utility of TEROSA in advancing our understanding of T cell behavior in leukemia and underscore its potential for broader applications in single-cell analysis.

Micro-scale thermofluidics enable autonomous and scalable CRISPR diagnostics for sexually transmitted infections screening

The development of clustered regularly interspaced short palindromic repeats (CRISPR)-based nucleic acid detection has recently been a center of interest for next-generation molecular diagnostics. Despite considerable advances, simple and effective strategies to harness the isothermal amplification reaction and CRISPR-based detection for maximal performance and minimal complexity are still desirable. Here, a thermofluidic approach leverages the micro-scale chemical and physical mechanism to perform autonomous and scalable CRISPR-based diagnostics (CRISPR-Dx) in a greatly simplified format, which was called "Thermofluidic CRISPR". Originating from the concept of convective PCR, it utilizes looped microchannel reactors to perform approximatively undisturbed isothermal amplification reaction at balanced temperature by virtue of the restricted molecular diffusion across the microchannel, in which the reagents of two reactions are compartmentalized virtually; then it creates circulatory flow within the loop channel to mix the amplificons and CRISPR reagents via Rayleigh-Bénard thermal convection, by simply warming up one side of the loop channel. Due to the simplicity and scalability, a low-cost, battery-powered, portable diagnostic platform, incorporating with smartphone-enabled real-time fluorescence readout, to perform rapid (<30 min), highly sensitive (2 copies per reaction), quantitative and multiplexed CRISPR-Dx was constructed. Its diagnostic performance in rapid screening of multiple pathogens from 196 clinical samples for syndromic testing of sexually transmitted infections was evaluated, exhibiting 97.4 % sensitivity and 100 % specificity benchmarked against the laboratory-based testing. Leveraging the micro-scale chemical and physical mechanism to simplify workflows for CRISPR-Dx may enhance their versatility and facilitate their broader applicability at the point of care.

Artificial intelligence enhanced microfluidic system for multiplexed point-of-care-testing of biological thiols

Cysteamine (CA) serves as a cystine-depleting agent employed in the management of cystinosis and a range of other medical conditions. Monitoring blood CA levels at the point of care is imperative due to the risk of toxicity associated with elevated CA dosages. An additional significant challenge is presented by the intricate composition of human plasma and the presence of various interfering biological thiols, which possess similar structures or properties. Here, this work proposes an AI-enhanced Lab-on-a-disc system, also termed AI-LOAD, for multiplexed point-of-care testing of cysteamine. The AI-LOAD system incorporates an online whole blood separation mechanism alongside a naked-eye colorimetric detection module, facilitating the rapid and precise visual identification of cysteamine. Remarkably, the system necessitates only 40 μL of whole blood to analyze eight samples within 3-min, achieving a limit of detection as low as 10 μM, which is lower than the physiological toxic concentration of 0.1 mM. By leveraging diverse colorimetric responses generated through interactions between gold nanoparticles of varying sizes and different biological thiols, combined with artificial intelligence methodologies, the system successfully accomplished specific recognition of various biological thiols with 100 % accuracy. The proposed AI-LOAD will drive advancements in centrifugal microfluidics for point-of-care testing, thereby holding potential for broader applications in future biomedical research and in vitro diagnosis.

The nucleic acid detection using CRISPR/Cas biosensing system with micro-nano modality for point-of-care applications

Nucleic acid detection is considered the golden standard for diagnosing infectious diseases caused by various pathogens, including viruses, bacteria, and parasites. PCR and other amplification-based technologies are highly sensitive and specific, allowing for accurate detection and identification of low-level causative pathogens by targeting and amplifying their unique genetic segment (DNA or RNA). However, it is important to recognize that machinery-dependent diagnostic methods may only sometimes be available or practical in resource-limited settings, where direct implementation can be challenging. CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-based diagnostics offer a promising alternative for nucleic acid detection. These methods provide gene sequence-specific targeting, multiplexing capability, rapid result disclosure, and ease of operation, making them suitable for point-of-care (POC) applications. CRISPR-Cas-based nucleic acid detection leverages the intrinsic gene-editing capabilities of CRISPR systems to detect specific DNA or RNA sequences with high precision, ensuring high specificity in identifying pathogens. When integrated with micro- and nano-technologies, CRISPR-based diagnostics gain additional benefits, including automated microfluidic processes, enhanced multiplexed detection, improved sensitivity through nanoparticle integration, and combined detection strategies. In this review, we analyze the motivations for tailoring the CRISPR-Cas system with microfluidic formats or nanoscale materials for nucleic acid biosensing and detection. We discuss and categorize current achievements in such systems, highlighting their differences, commonalities, and opportunities for addressing challenges, particularly for POC diagnostics. Micro- and nano-technologies can significantly enhance the practical utility of the CRISPR-Cas system, enabling more comprehensive diagnostic and surveillance capabilities. By integrating these technologies, CRISPR-based diagnostics can achieve higher levels of automation, sensitivity, and multiplexing, making them invaluable tools in the global effort to diagnose and control infectious diseases.

Human papilloma virus (HPV) mediated cancers: an insightful update

Human papillomavirus (HPV), a DNA virus, is a well-documented causative agent of several cancers, including cervical, vulvar, vaginal, penile, anal, and head & neck cancers. Major factors contributing to HPV-related cancers include persistent infection and the oncogenic potential of particular HPV genotypes. High-risk HPV strains, particularly HPV-16 and HPV-18, are responsible for over 70% of cervical cancer cases worldwide, as well as a significant proportion of other genital and head and neck cancers. At the molecular level, the oncogenic activity of these viruses is driven by the overexpression of E6 and E7 oncoproteins. These oncoproteins dysregulate the cell cycle, inhibit apoptosis, and promote the accumulation of DNA damage, ultimately transforming normal cells into cancerous ones. This review aims to provide a comprehensive overview of the recent advances in HPV-related cancer biology and epidemiology. The review highlights the molecular pathways of HPV-driven carcinogenesis, focusing on the role of viral oncoproteins in altering host cell targets and disrupting cellular signalling pathways. The review explores the therapeutic potential of these viral proteins, and discusses current diagnostic and treatment strategies for HPV-associated cancers. Furthermore, the review highlights the critical role of HPV in the development of various malignancies, emphasizing the persistent challenges in combating these cancers despite advancements in vaccination and therapeutic strategies. We also emphasize recent breakthroughs in utilizing biomarkers to monitor cancer therapy responses, such as mRNAs, miRNAs, lncRNAs, proteins, and genetic markers. We hope this review will serve as a valuable resource for researchers working on HPV, providing insights that can guide future investigations into this complex virus, which continues to be a major contributor to global morbidity and mortality.

DNA Fragment Fusion and Nucleic Acid Detection by Fusion Recombinase-Aided Amplification

Constructing fusion DNA fragments is frequently used for genetic engineering purposes. To date, fusion PCR is one of the most popular approaches for generating fusion DNA fragments. Here, we describe a novel method for DNA fusion based on the isothermal DNA amplification technique, recombinase-aided amplification (RAA). We demonstrate that this method, termed "fusion RAA", can assemble two to three DNA fragments to generate a fusion fragment of up to ∼1 kb in a one-pot reaction within 40 min at 37 °C. We further demonstrate that fusion RAA can realize fragment insertion, deletion, and base mutation. Moreover, we show that fusion RAA can be harnessed to facilitate pathogen detection by simultaneously targeting two genes in one RAA assay, as demonstrated by the rapid and simplified detection of methicillin-resistant Staphylococcus aureus (MRSA). Based on fusion RAA, we establish two novel pathogen detection platforms, FREAC (Fusion REcombinase-aided Amplification combined with CRISPR/Cas13a) and FREAL (Fusion REcombinase-aided Amplification combined with Lateral flow assay). Using these two platforms, we can detect clinical MRSA strains within 55 min with high specificity and a limit of detection of 150 copies/μL of genomic DNA, highlighting their potential as user-friendly platforms for nucleic acid detection.

Deep Learning-Enhanced Hand-Driven Microfluidic Chip for Multiplexed Nucleic Acid Detection Based on RPA/CRISPR

The early detection of high-risk human papillomavirus (HR-HPV) is crucial for the assessment and improvement of prognosis in cervical cancer. However, existing PCR-based screening methods suffer from inadequate accessibility, which dampens the enthusiasm for screening among grassroots populations, especially in resource-limited areas, and contributes to the persistently high mortality rate of cervical cancer. Here, a portable system is proposed for multiplexed nucleic acid detection, termed R-CHIP, that integrates Recombinase polymerase amplification (RPA), CRISPR detection, Hand-driven microfluidics, and an artificial Intelligence Platform. The system can go from sample pre-processing to results readout in less than an hour with simple manual operation. Optimized for sensitivity of 10-17 M for HPV-16 and 10-18 M for HPV-18, R-CHIP has an accuracy of over 95% in 300 tests on clinical samples. In addition, a smartphone microimaging system combined with the ResNet-18 deep learning model is used to improve the readout efficiency and convenience of the detection system, with initial prediction accuracies of 96.0% and 98.0% for HPV-16 and HPV-18, respectively. R-CHIP, as a user-friendly and intelligent detection platform, has great potential for community-level HR-HPV screening in resource-constrained settings, and contributes to the prevention and early diagnosis of other diseases.

Engineered CRISPR/Cas Ribonucleoproteins for Enhanced Biosensing and Bioimaging

CRISPR-Cas systems represent a highly programmable and precise nucleic acid-targeting platform, which has been strategically engineered as a versatile toolkit for biosensing and bioimaging applications. Nevertheless, their analytical performance is constrained by inherent functional and activity limitations of natural CRISPR/Cas systems, underscoring the critical role of molecular engineering in enhancing their capabilities. This review comprehensively examines recent advancements in engineering CRISPR/Cas ribonucleoproteins (RNPs) to enhance their functional capabilities for advanced molecular detection and cellular imaging. We explore innovative strategies for developing enhanced CRISPR/Cas RNPs, including Cas protein engineering through protein mutagenesis and fusion techniques, and guide RNA engineering via chemical and structural modifications. Furthermore, we evaluate these engineered RNPs' applications in sensitive biomarker detection and live-cell genomic DNA and RNA monitoring, while analyzing the current challenges and prospective developments in CRISPR-Cas RNP engineering for advanced biosensing and bioimaging.

Application of CRISPR-Cas System in Human Papillomavirus Detection Using Biosensor Devices and Point-of-Care Technologies

Human papillomavirus (HPV) is the most common virus for genital tract infections. Cervical cancer ranks as the fourth most prevalent cancer globally, with over 99% of cases in women attributed to HPV infection. This infection continues to pose an ongoing threat to public health. Therefore, the development of rapid, high-throughput, and sensitive HPV detection platforms is important, especially in regions with limited access to advanced medical resources. CRISPR-based biosensors, a promising new method for nucleic acid detection, are now rapidly and widely used in basic and applied research and have received much attention in recent years for HPV diagnosis and treatment. In this review, we discuss the mechanisms and functions of the CRISPR-Cas system, focusing on its applications in HPV diagnostics. The review covers CRISPR technologies such as CRISPR-Cas9, CRISPR-Cas12, and CRISPR-Cas13, along with nucleic acid amplification methods, CRISPR-based signal output systems, and point-of-care testing (POCT) strategies. This comprehensive overview highlights the versatility and potential of CRISPR technologies in HPV detection. We also discuss the numerous CRISPR biosensors developed since the introduction of CRISPR to detect HPV. Finally, we discuss some of the challenges faced in HPV detection by the CRISPR-Cas system.

FEN1-Aided RPA (FARPA) Coupled with Autosampling Microfluidic Chip Enables Highly Multiplexed On-Site Pathogen Screening

A simple, rapid, low-cost, and multiplex detection platform is crucial for the diagnosis of infectious diseases, especially for on-site pathogen screening. However, current methods are difficult to satisfy the requirements for minimal instrument and multiplexed point-of-care testing (POCT). Herein, we propose a versatile and easy-to-use platform (FARPA-chip) by combining multiplex FARPA with an autosampling microfluidic chip. A pair of universal recombinase polymerase amplification (RPA) primers introduced during double-stranded cDNA (ds-cDNA) preparation are employed to amplify multiple targets, followed by amplicon-decoding with the chip, indicating no bias in amplifying different targets due to the universal RPA primers. FARPA-chip exhibits that as low as 10 copies of each target RNA in the starting sample can be sensitively detected by 12-plex detection of vector-borne viruses within 45 min and no cross-talk is observed between different targets. The feasibility of this platform is confirmed by designing a 9-plex FARPA-chip to detect 6 kinds of clinically common respiratory viruses from 16 clinical samples of nasopharyngeal swabs, and the results are completely consistent with RT-qPCR. Furthermore, by integrating quick extraction reagent, the turnaround time can be significantly decreased to <50 min, highlighting that our FARPA-chip enables a cost-effective on-site pathogen screening with a relatively high level of multiplexing. Depending on the number of chambers in the chip, the current design is theoretically capable of detecting up to 24 different pathogens, which should fulfill most clinical purposes. We believe that the proposed platform could provide an effective way for a series of healthcare-related applications in resource-limited settings.

CRISPR-Cas12a/Cas13a Multiplex Bioassay for ctDNA and miRNA by Mass Spectrometry

The CRISPR-Cas system, particularly CRISPR-Cas12a and CRISPR-Cas13a, has been widely utilized in constructing various biosensors due to their "trans-cleavage" ability as a means of signal amplification. However, this universal "trans-cleavage" characteristic also presents a challenge for realizing CRISPR-Cas multiplexed bioanalysis. Besides, potential signal cascading interference and complicated design are notable obstacles in CRISPR-Cas multiplexed bioanalysis. Herein, we propose a mass spectrometry method that leverages the CRISPR-Cas12a/13a system to achieve simultaneous detection of ctDNA and miRNA. Based on the properties of the CRISPR-Cas12a/13a system, two types of nanoparticle reporter probes have been engineered, using cancer-related biomarkers ctDNA and miR-21 as our model analytes. The nanoparticle tags, which intrinsically incorporated millions of detectable atoms, combined with the CRISPR-Cas12a/Cas13a system's "trans-cleavage" ability, allow the proposed mass spectrometry strategy to achieve fmol-level detection limits without any nucleic acid amplification procedures. The assay was successfully applied to human serum samples, demonstrating its potential for early disease diagnosis and progression tracking.

Visual detection of HPV16 using a photoactivatable CRISPR-Cas12 system

Human papillomavirus (HPV) screening is crucial for the diagnosis of cervical cancer. In this study, we have combined photoactivated CRISPR-Cas12a with tube-in-tube structure and recombinase polymerase amplification (RPA) to enable simple, rapid and convenient visualization detection of HPV16, facilitated by blue UV light at 302 nm. It serves as a potential tool for on-site diagnostic use, which could be beneficial in terms of portability and speed.

Unveiling a novel RNA G-triplex structure: its function and potential in CRISPR-based diagnostics

We report the discovery of a novel higher-order RNA structure, RNA G-triplex (rG3), formed by the TERRA sequence. Through CD spectroscopy, NMR analysis, and molecular modeling, we confirmed its stable, parallel conformation. rG3 exhibits strong binding to thioflavin T (ThT), N-methyl mesoporphyrin IX (NMM), and hemin, showcasing its potential as a biosensing element. Additionally, CRISPR-Cas13a trans-cleaves rG3, demonstrating its utility as a sensitive reporter in diagnostic applications. These findings expand the structural diversity of RNA and suggest new avenues for RNA-based biosensors and CRISPR diagnostics.

A Streamlined Point-of-Care CRISPR Test for Tuberculosis Detection Directly from Sputum

Mycobacterium tuberculosis (Mtb) is a major threat to global health and is responsible for over one million deaths each year. To stem the tide of cases and maximize opportunities for early interventions, there is an urgent need for affordable and simple means of tuberculosis diagnosis in under-resourced areas. We sought to develop a CRISPR-based isothermal assay coupled with a compatible, straightforward sample processing technique for point-of-care use. Here, we combine Recombinase Polymerase Amplification (RPA) with Cas13a and Cas12a, to create two parallelised one-pot assays that detect two conserved elements of Mtb (IS6110 and IS1081) and an internal control targeting human DNA. These assays were shown to be compatible with lateral flow and can be readily lyophilized. Our finalized assay exhibited sensitivity over a wide range of bacterial loads (105 to 102 CFU/mL) in sputum. The limit of detection (LoD) of the assay was determined to be 69.0 (51.0 - 86.9) CFU/mL for Mtb strain H37Rv spiked in sputum and 80.5 (59.4 - 101.6) CFU/mL for M. bovis BCG. Our assay showed no cross reactivity against a wide range of bacterial/fungal isolates. Clinical tests on 13 blinded sputum samples revealed 100% (6/6) sensitivity and 100% (7/7) specificity compared to culture. Our assay exhibited comparable sensitivity in clinical samples to the microbiological gold standard, TB culture, and to the nucleic acid state-of-the-art, GeneXpert MTB/RIF Ultra. This technology streamlines TB diagnosis from sample extraction to assay readout in a rapid and robust format, making it the first test to combine amplification and detection while being compatible with both lateral flow and lyophilization.

Emerging microfluidic technologies for CRISPR-based diagnostics: an overview

In recent years, CRISPR (clustered regularly interspaced short palindromic repeats) has emerged as a detection technique with high specificity and sensitivity. However, it still needs improvements in terms of reducing cost, complexity, cross-contamination, technical requirements, and lack of quantification platforms. Microfluidic strategies can advance CRISPR-based technology and be modified to a higher level in the future. This review provides an overview of CRISPR-based detection systems (CRISPR-Dx) and their mechanism. Then, it explains how they have been optimized for fast and accurate point-of-care testing (POCT) using microfluidic devices such as SHINE, CARMEN, DNAiTECH, Dμchip, MAPnavi, FAST, and ITP. We discuss their innovations, primarily focusing on how they develop CRISPR-Dx in detection throughput, quantification, simple operation, visualization, sensitivity, specificity, and anti-contamination.

Construction of Multiplexed Assays on Single Anisotropic Particles Using Microfluidics

Considerable efforts have been made to develop microscale multiplexing strategies. However, challenges remain due to the difficulty in deploying functional objects and decoding high-density signals on anisotropic microcarriers. Here, we report a microfluidic method to fabricate architecture-marked anisotropic particles for performing designable multiplexed assays in a label-free manner. By controlling fluid assembly and rapid in-air cross-linking, the particles are endowed with multiple functional regions and a unique architecture identifier. The marked architecture enables an addressing mechanism that allows the profiling of embedded label-free objects by mapping a well-defined reference architecture onto the target particle. By loading analytes of interest, such as molecular probes or cells, we showed the potential of these structurally flexible particles for detecting microRNAs and studying cell interactions. The architecture-marked particles represent a new approach for single-entity assays and can be the basis for exploring more advanced microscale multiplexed applications.

Demystifying EV heterogeneity: emerging microfluidic technologies for isolation and multiplexed profiling of extracellular vesicles

Extracellular vesicles (EVs) are heterogeneous lipid containers carrying complex molecular cargoes, including proteins, nucleic acids, glycans, etc. These vesicles are closely associated with specific physiological characteristics, which makes them invaluable in the detection and monitoring of various diseases. However, traditional isolation methods are often labour-intensive, inefficient, and time-consuming. In addition, single biomarker analyses are no longer accurate enough to meet diagnostic needs. Routine isolation and molecular analysis of high-purity EVs in clinical applications is even more challenging. In this review, we discuss a promising solution, microfluidic-based techniques, that combine efficient isolation and multiplex detection of EVs, to further demystify EV heterogeneity. These microfluidic-based EV multiplexing platforms will hopefully facilitate development of liquid biopsies and offer promising opportunities for personalised therapy.

Dual-OR Logic-Gated Lateral Flow Strip Assay Based on Colorimetric-Fluorescence Dual Indication for Screening of HPV16/18 in Multiple Scenarios

The incidence of cervical cancer continues to rise in underdeveloped regions due to low human papillomavirus (HPV) vaccination rates and inadequate screening systems. To achieve convenient, rapid, and accurate detection of HPV, we developed a three-wire lateral flow strip assay system based on dual-OR logic gates for rapid and simultaneous detection of HPV subtypes 16 and 18 in a single test. The system combines three-branch-catalytic hairpin assembly (TCHA)-mediated signal amplification with simple OR logic gate-based signal output to improve detection rates while enabling HPV 16/18 subtype identification. The detection limit of the method was calculated to be 10 aM for the selected target sequences. Meanwhile, the method showed excellent specificity with no false-positive output in real-world detection. The sensitivity of the colorimetric test strips exceeded 90%, while the sensitivity of the fluorescence-based test strips surpassed 95% in detecting clinical samples, demonstrating a high degree of concordance with the results obtained from the real-time quantitative polymerase chain reaction (qPCR). This method provides a simple and easy method for the rapid screening of HPV.

Detecting CYP2C19 genes through an integrated CRISPR/Cas13a-assisted system

CYP2C19 gene single nucleotide polymorphisms (SNPs) should be considered in the clinical use of clopidogrel as they have important guiding value for predicting the risk of bleeding and thrombosis after clopidogrel treatment. The CRISPR/Cas system is increasingly used for SNP detection owing to its single-nucleotide mismatch specificity. Simultaneous detection of multiple SNPs for rapid identification of the CYP2C19 genotype is important, but there is no method to detect a wide variety of CYP2C19 SNPs. This study proposes a new integrated system that integrates the PCR reaction and CRISPR/Cas detection of three CYP2C19 genes on a device, achieving rapid, sensitive, and specific detection. In our design, magnetic beads with three different sizes capture target nucleic acid from the sample, which are dragged through different areas by magnetic force, for PCR amplification reaction and CRISPR/Cas13a detection of CYP2C19*2, CYP2C19*3 and CYP2C19*17 genes. Note that magnetic beads were sorted via microporous PC membranes of different apertures. This study exhibits a broad clinical application prospect and provides a favorable tool for clinical clopidogrel administration.

Using CRISPR for viral nucleic acid detection

Pathogenic microorganisms, such as viruses, have threatened human health and will continue to contribute to future epidemics and pandemics, highlighting the importance of developing effective diagnostics. To contain viral outbreaks within populations, fast and early diagnosis of infected individuals is essential. Although current standard methods are highly sensitive and specific, like RT-qPCR, some can have slow turnaround times, which can hinder the prevention of viral transmission. The discovery of CRISPR-Cas systems in bacteria and archaea initially revolutionized the world of genome editing. Intriguingly, CRISPR-Cas enzymes also have the ability to detect nucleic acids with high sensitivity and specificity, which sparked the interest of researchers to also explore their potential in diagnosis of viral pathogens. In particular, the CRISPR-Cas13 system has been used as a tool for detecting viral nucleic acids. Cas13's capability to detect both target RNA and non-specific RNAs has led to the development of detection methods that leverage these characteristics through designing specific detection read-outs. Optimization of viral sample collection, amplification steps and the detection process within the Cas13 detection workflow has resulted in assays with high sensitivity, rapid turnaround times and the capacity for large-scale implementation. This review focuses on the significant innovations of various CRISPR-Cas13-based viral nucleic acid detection methods, comparing their strengths and weaknesses while highlighting Cas13's great potential as a tool for viral diagnostics.

Expanding Cas12a Activity Control with an RNA G-Quadruplex at the 5' end of CRISPR RNA

Precise control of Cas12a activity is essential for the improvement of the detection limit of clinical diagnostics and the minimization of errors. This study addresses the challenge of controlling Cas12a activity, especially in the context of nucleic acid detection where the inherent incompatibility between isothermal amplification and CRISPR reactions complicates accurate diagnostics. An RNA G-quadruplex (RG4) structure at the 5' end of crRNA is introduced to modulate Cas12a activity accurately without the need for chemical modifications. The results indicate that the presence of RG4 does not significantly impact Cas12a's cleavage activity but can be controlled by RG4 stabilizers, enabling the suppression and subsequent restoration of Cas12a activity with potential for precise activity control. Moreover, the use of RG4 is expanded by incorporating it into split crRNA, introducing RG4 directly at the 5' end of the direct repeat (DR) region, enabling tailored activity regulation for different targets by matching with various Spacer regions. Additionally, a light-controlled one-pot method for activating Cas12a is developed, thereby enhancing the accuracy and sensitivity of clinical samples. This study showcases the pioneering use of RG4 in manipulating Cas12a activity, streamlining diagnostics, and paving the way for advances in clinical nucleic acid testing.

Rapid and Sensitive On-Site Nucleic Acid Detection of Three Main Fusarium Pathogens of Maize Stalk Rot Based on RPA-CRISPR/Cas12a

Maize stalk rot is a soilborne disease that poses a serious threat to maize production worldwide, with the most significant cause being fungal stalk rot. The development of a visual and rapid detection method for the maize stalk rot pathogen is significant for its prompt and accurate identification, enhancing agricultural production efficiency, and implementing timely preventive measures. These measures will help safeguard the maize yield and quality, ultimately reducing agricultural losses. In this study, we aimed to develop an efficient method to detect maize stalk rot pathogens. We focused on three pathogenic fungi commonly found in maize-producing regions worldwide: Fusarium verticillioides, F. proliferatum, and F. graminearum. Based on translation elongation factor 1-α, we developed a rapid detection technique using recombinase polymerase amplification-CRISPR/Cas12a, combined with test strips to develop an on-site rapid visual detection test for these pathogens. The method showed detection sensitivity for F. verticillioides, F. proliferatum, and F. graminearum within 20 min at concentrations of 7.8 pg/μl, 0.11 ng/μl, and 0.13 ng/μl, respectively. The sensitivity increased with increasing reaction time. Testing of field disease samples indicated that the method is effective in detecting nucleic acids obtained through crude extraction methods. In conclusion, we developed a visually rapid detection technology that does not rely on complex instruments and equipment for the on-site early detection of F. verticillioides, F. proliferatum, and F. graminearum in the field to implement effective control measures, ensuring stable and high maize yields.

Direct repeat region 3' end modifications regulate Cas12a activity and expand its applications

CRISPR-Cas12a technology has transformative potential, but as its applications grow, enhancing its inherent functionalities is essential to meet diverse demands. Here, we reveal a regulatory mechanism for LbCas12a through direct repeat (DR) region 3' end modifications and de-modifications, which can regulate LbCas12a's cis- and trans-cleavage activities. We extensively explored the effects of introducing phosphorylation, DNA, photo-cleavable linker, DNA modifications at the DR 3' end on LbCas12a's functionality. We find that the temporary inhibitory function of Cas12a can be reactivated by DR 3' end modification corresponding substances, such as alkaline phosphatase (ALP), immunoglobulin G (IgG), alpha-fetoprotein (AFP), DNA exonucleases, ultraviolet radiation, and DNA glycosylases, which greatly expand the scope of application of Cas12a. Clinical applications demonstrated promising results in ALP, AFP, and trace Epstein-Barr virus detection compared to gold standard methods. Our research provides valuable insights into regulating LbCas12a activity through direct modification of DR and significantly expands its potential clinical detection targets, paving the way for future universal clustered regularly interspaced short palindromic repeats (CRISPR) diagnostic strategies.

Surveillance of antimicrobial resistance using isothermal amplification: a review

The monitoring of antibiotic resistance genes (ARGs) is crucial for understanding the level of antimicrobial resistance and the associated health burden, which in turn is essential for the control and prevention of antimicrobial resistance (AMR). Isothermal amplification, an emerging molecular biology technology, has been widely used for drug resistance detection. Furthermore, its compatibility with a range of technologies enables high-specificity, high-throughput, and portable and integrated detection in drug resistance, particularly in resource-limited areas. However, to date, reviews involved in isothermal amplification all concentrate on its technological advancements and its application in nucleic acid point-of-care testing. Few reviews have been published that focus specifically on the application of isothermal amplification in the detection of drug resistance. This review summarizes the detection principles of different isothermal amplification techniques and discusses their strengths and weaknesses as well as the applicable scenarios for drug resistance detection. It also summarizes advances in the application, challenges and prospects of isothermal amplification technologies in conjunction with different methods such as base mismatch, CRISPR-Cas, lateral flow immunoassay, sensing and microfluidic technologies for improvement of specificity, throughput and integration for drug resistance detection. It is anticipated that this review will assist scientists in comprehending the evolution of isothermal amplification in the context of drug resistance detection and provide insights into the prospective applications of isothermal amplification for highly integrated and immediate on-site detection of drug resistance.

Multiplex Digital Nucleic Acid Analysis by a LAMP-Argonaute Coupling Assay via a Parallel Droplet Fusion SlipChip

Multiplex digital nucleic acid analysis (NAA) allows the precise quantification of multiple target nucleic acids with single-molecule sensitivity, making it highly appealing for life science research and clinical diagnostics. Nucleic acid-guided endonucleases, such as CRISPR, have demonstrated great potential in digital NAA. However, performing multiplex digital NAA with an endonuclease remains challenging. The thermophilic Argonaute protein (Ago) enables specific targeting of multiple sequences by a single enzyme, exhibiting superior potential in multiplex detection. Here, we developed a multiplex digital NAA by coupling nucleic acid amplification and Ago-specific detection using parallel droplet fusion facilitated by a SlipChip. The SlipChip can generate a series of droplets to perform multiplex digital loop-mediated isothermal amplification (LAMP), followed by a series of droplets containing Ago reagents for parallel mixing and reactions, resulting in three distinct digital fluorescence signals (FAM, ROX, and Cy5) corresponding to each specific target sequence. We performed viral load analysis of respiratory viruses, including influenza A, influenza B, and SARS-CoV-2, within 60 min. In addition, we used this digital LAMP-Ago assay to analyze viral loads in 34 clinical samples. The system provides a multiplex digital NAA capable of precise nucleic acid quantification with high sensitivity and specificity.

Development and evaluation of a CRISPR/Cas12a-based diagnostic test for rapid detection and genotyping of HR-HPV in clinical specimens

Persistent infection with high-risk human papillomavirus (HR-HPV) is the principal etiological factor of cervical cancer. Considering the gradual progression of cervical cancer, the early, rapid, sensitive, and specific identification of HPV, particularly HR-HPV types, is crucial in halting the advancement of the illness. Here, we established a rapid, highly sensitive, and specific HR-HPV detection platform, leveraging the CRISPR/Cas12a assay in conjunction with multienzyme isothermal rapid amplification. Our platform enables the detection and genotyping of 14 types of HR-HPV by using type-specific crRNAs. The outcomes of the detection can be interpreted either through a fluorescence reader or visually. Furthermore, we achieved one-tube multiplex detection of 14 HR-HPV types through the use of multiple amplifications and a crRNA pool. The detection sensitivity of this method is 2 copies/μL with no cross-reactivity, and the results can be obtained within 30 minutes. This method exhibited 100% clinical sensitivity and 100% clinical specificity when applied to 258 clinical specimens. Based on these findings, our CRISPR/Cas-based HR-HPV detection platform holds promise as a novel clinical detection tool, offering a visually intuitive and expedited alternative to existing HPV infection diagnostics and providing fresh perspectives for clinical cervical cancer screening.IMPORTANCEThis study developed a novel high-risk human papillomavirus (HR-HPV) detection platform based on CRISPR/Cas12a technology. This platform not only enables the rapid, highly sensitive, and specific detection and genotyping of 14 types of HR-HPV but also achieves single-tube multiplex detection of 14 HR-HPV types through ingenious design. The outcomes of the detection can be interpreted either through a fluorescence reader or visually. To the best of our knowledge, this is the first paper to utilize CRISPR/Cas diagnostic technology for the simultaneous detection of 14 types of HPV and to evaluate its feasibility in clinical sample detection using a large number of clinical samples. We hope that this work will facilitate the rapid and accurate detection of HPV and promote the broader application of CRISPR/Cas diagnostic technology.

Phase Transition of Wax Enabling CRISPR Diagnostics for Automatic At-Home Testing of Multiple Sexually Transmitted Infection Pathogens

Sexually transmitted infections (STIs) significantly impact women's reproductive health. Rapid, sensitive, and affordable detection of these pathogens is essential, especially for home-based self-testing, which is crucial for individuals who prioritize privacy or live in areas with limited access to healthcare services. Herein, an automated diagnostic system called Wax-CRISPR has been designed specifically for at-home testing of multiple STIs. This system employs a unique strategy by using the solid-to-liquid phase transition of wax to sequentially isolate and mix recombinase polymerase amplification (RPA) and CRISPR assays in a microfluidic chip. By incorporating a home-built controlling system, Wax-CRISPR achieves true one-pot multiplexed detection. The system can simultaneously detect six common critical gynecological pathogens (CT, MG, UU, NG, HPV 16, and HPV 18) within 30 min, with a detection limit reaching 10-18 M. Clinical evaluation demonstrates that the system achieves a sensitivity of 96.8% and a specificity of 97.3% across 100 clinical samples. Importantly, eight randomly recruited untrained operators performe a double-blinded test and successfully identified the STI targets in 33 clinical samples. This wax-transition-based one-pot CRISPR assay offers advantages such as low-cost, high-stability, and user-friendliness, making it a useful platform for at-home or field-based testing of multiple pathogen infections.

Programmable Multiplexed Nucleic Acid Detection by Harnessing Specificity Defect of CRISPR-Cas12a

CRISPR-Cas12a works like a sophisticated algorithm in nucleic acid detection, yet its challenge lies in sometimes failing to distinguish targets with mismatches due to its specificity limitations. Here, the mismatch profiles, including the quantity, location, and type of mismatches in the CRISPR-Cas12a reaction, are investigated and its various tolerances to mismatches are discovered. By harnessing the specificity defect of the CRISPR-Cas12a enzyme, a dual-mode detection strategy is designed, which includes approximate matching and precise querying of target sequences and develop a programmable multiplexed nucleic acid assay. With the assay, 14 high-risk human papillomavirus (HPV) subtypes are simultaneously detected, collectively responsible for 99% of cervical cancer cases, with attomolar sensitivity. Specifically, the assay not only distinguishes HPV16 and HPV18, the two most common subtypes but also detects 12 other high-risk pooled HPV subtypes. To enable low-cost point-of-care testing, the assay is incorporated into a paper-based microfluidic chip. Furthermore, the clinical performance of the paper-based microfluidic chip is validated by testing 75 clinical swab samples, achieving performance comparable to that of PCR. This programmable multiplexed nucleic acid assay has the potential to be widely applied for sensitive, specific, and simultaneous detection of different pathogens.

CRISPR/Cas12a dual-mode biosensor for Staphylococcus aureus detection via enzyme-free isothermal amplification

Accurate and reliable detection of Staphylococcus aureus (S. aureus) is essential for preventing infections, particularly in healthcare and food safety contexts. This work presents a novel dual-mode biosensor that integrates the CRISPR/Cas12a system with an enzyme-free isothermal amplification method for detecting S. aureus. Hybridization chain reaction (HCR) and catalytic hairpin assembly (CHA) amplify the aptamer-triggered response, significantly enhancing sensitivity. CRISPR/Cas12a's nuclease activity is utilized in two modes: cis cleavage generates a fluorescence signal, while trans cleavage produces an electrochemical signal, enabling dual-mode detection. The biosensor demonstrates outstanding performance, with a limit of detection (LOD) as low as 5.7 CFU mL-1 in electrochemical mode and 133.7 CFU mL-1 in fluorescence mode, showcasing excellent accuracy, stability, and sensitivity. It has been successfully applied to detecting actual samples, confirming its practical applicability. This innovative approach offers a powerful tool for the swift and precise identification of S. aureus and paves the way for developing next-generation dual-mode biosensors for various analytes. Future research will aim to simplify the detection process further, making it more accessible for use in resource-limited settings.

SlipChip Enables the Integration of CRISPR-Cas12a and RPA for Fast and Stand-Alone HPV Detection

Human papillomavirus (HPV) screening is vital for the early detection and prevention of cervical cancer. However, existing methods often face challenges related to speed, simplicity, and multiplexing, especially in resource-limited settings. Here we developed a portable SlipChip-based multiplexed and rapid nucleic acid testing platform, named SMART, designed to simultaneously detect HPV16 and HPV18. SMART allows seamless integration of the RPA and Cas12a assays on the SlipChip and includes a heating membrane to regulate the on-chip assay temperatures. This allows SMART to operate as a stand-alone platform without additional control instruments. The platform also features an All-in-One imaging mode for rapid on-chip data acquisition, enhancing its performance. SMART enables sensitive detection of HPV16 and HPV18 DNA across multiple samples in just 36 min with a detection limit of approximately 6 copies per reaction. Testing of 56 clinical samples at risk of HPV infection validated SMART's performance, showing 97.7% sensitivity and 100% specificity. In summary, SMART offers a stand-alone system capable of rapidly distinguishing between the two most harmful HPV subtypes, showcasing the significant potential for rapid, multiplexed nucleic acid testing in various applications.

Self-Interference Digital Optofluidic Genotyping for Integrated and Automated Label-Free Pathogen Detection

Pathogen, prevalent in both natural and human environments, cause approximately 4.95 million deaths annually, ranking them among the top contributors to global mortality. Traditional pathogen detection methods, reliant on microscopy and cultivation, are slow and labor-intensive and often produce subjective results. While nucleic acid amplification techniques such as polymerase chain reaction offer genetic accuracy, they necessitate costly laboratory equipment and skilled personnel. Consequently, isothermal amplification methods like recombinase polymerase amplification (RPA) have attracted interest for their rapid and straightforward operations. However, these methods face challenges in specificity and automated sample processing. In this study, we introduce a self-interferometric digital optofluidic platform incorporating asymmetric direct solid-phase RPA for real-time, label-free, and automated pathogen genotyping. By integration of digital microfluidics with a DNA monolayer detection method using hyperspectral interferometry, this platform enables rapid, specific, and sensitive pathogen detection without the need for exogenous labeling or complex procedures. The system demonstrated high sensitivity (10 CFU·mL-1), specificity (differentiating four Candida species), detection efficiency (fully automated within 50 min for Gram-negative bacteria), and throughput (simultaneous detection of four indices). This integrated approach to pathogen quantitation on a single microfluidic chip represents a significant advancement in rapid pathogen diagnostics, providing a practical solution for timely pathogen detection and analysis.

Isothermal nucleic acid amplification for monitoring hand-foot-and-mouth disease: current status and future implications

With the global prevalence of the hand-foot-and-mouth disease (HFMD) epidemic, the development of reliable point-of-care testing (POCT) is crucial for the timely identification and prevention of outbreaks. Isothermal nucleic acid amplification techniques (INAATs) have attracted much attention because of their high efficiency for rapid diagnosis. In this work, we systematically summarize the current status of INAATs for HFMD and discuss advantages and drawbacks of various INAATs for HFMD. The INAATs for HFMD detection mainly include loop-mediated isothermal amplification (LAMP), simultaneous amplification and testing (SAT), and recombinase polymerase amplification (RPA). Among them, LAMP has excelled in several diagnostic metrics and has made significant progress in the field of POCT. SAT has been effective in overcoming the problem of RNA degradation. RPA is suited for on-site testing due to its rapid amplification rate and low reaction temperature. In addition, this study explores the potential of INAATs in lateral flow strips (LFS) test and microfluidic devices for HFMD. LFS is typically used for qualitative analysis and supports multiple detection. Microfluidics can integrate necessary processes of sample pre-processing, amplification, and signal output, enabling high-throughput qualitative or quantitative detection and demonstrating the potential of monitoring HFMD. We hope the current work will provide insights into INAATs for monitoring HFMD and serve as a reference for the implementation of on-site EV detection for public health.

Synthetic mismatches enable specific CRISPR-Cas12a-based detection of genome-wide SNVs tracked by ARTEMIS

Detection of pathogenic DNA variants is vital in cancer diagnostics and treatment monitoring. While CRISPR-based diagnostics (CRISPRdx) offer promising avenues for cost-effective, rapid, and point-of-care testing, achieving single-nucleotide detection fidelity remains challenging. We present an in silico pipeline that scans the human genome for targeting pathogenic mutations in the seed region (ARTEMIS), the most stringent crRNA domain. ARTEMIS identified 12% of pathogenic SNVs as Cas12a recognizable, including 928 cancer-associated variants such as BRAFV600E, BRCA2E1953∗, TP53V272M, and ALDH2E504K. Cas12a exhibited remarkable tolerance to single mismatches within the seed region. Introducing deliberate synthetic mismatches within the seed region yielded on-target activity with single-nucleotide fidelity. Both positioning and nucleobase types of mismatches influenced detection accuracy. With improved specificity, Cas12a could accurately detect and semi-quantify BRAFV600E in cfDNA from cell lines and patient liquid biopsies. These results provide insights toward rationalized crRNA design for high-fidelity CRISPRdx, supporting personalized and cost-efficient healthcare solutions in oncologic diagnostics.

CRISPR/Cas12a-enhanced DNA nanomachine for multiple respiratory pathogens detection

Respiratory infection caused by pathogens is among the most prevalent health issues affecting people worldwide. Accurate and rapid screening of respiratory pathogens is crucial for selecting appropriate treatments to control epidemics. However, it is often challenged by two aspects: first, the low concentration of pathogens in the early stages of infection; second, the difficulty of analyzing multiple pathogens. Herein, we report a mass spectrometry strategy combining the CRISPR/Cas12a system with DNA nanomachines for respiratory pathogens detection. Thanks to the high sensitivity of the CRISPR/Cas12a-enhanced DNA nanomachine and the multiple analysis of elemental mass spectrometry, the proposed method was successfully applied for clinical sample analysis with a low detection limit of 28 amol, 30 amol, and 38 amol for SARS-CoV-2, influenza A virus subtype H1N1, and Mycoplasma pneumoniae, respectively.

Toothpick DNA extraction combined with handheld LAMP microfluidic platform for simple and rapid meat authentication

Adulteration of meat is a global issue, necessitating rapid, inexpensive, and simple on-site testing methods. Therefore, the present study aimed to develop a one-minute toothpick-based DNA extraction method, a handheld microfluidic chip, and a smartphone-controlled portable analyzer for detecting multiple meat adulterations. A toothpick was inserted into the meat to promote DNA release and adsorption. Furthermore, a handheld microfluidic chip was designed for DNA elution on toothpicks and fluid distribution. Finally, a smartphone-actuated portable analyzer was developed to function as a heater, signal detector, and result reader. The portable device comprises a microcontroller, a fluorescence detection module, a step scanning unit, and a heating module. The proposed device is portable, and the app is user-friendly. This simple design, easy operation, and fast-response system could rapidly detect as little as 1% of simulated adulterated samples (following UK standards) within 40 min at a cost of less than USD 1 per test.

Rapid and simultaneous detection of common childhood diarrhea viruses by microfluidic-FEN1-assisted isothermal amplification with ultra-high specificity and sensitivity

Rapid and accurate diagnostic methods are crucial for managing viral gastroenteritis in children, a leading cause of global childhood morbidity and mortality. This study introduces a novel microfluidic-Flap endonuclease 1 (FEN1)-assisted isothermal amplification (MFIA) method for simultaneously detecting major viral pathogens associated with childhood diarrhea-rotavirus, norovirus, and adenovirus. Leveraging the specificity-enhancing properties of FEN1 with a universal dspacer-modified flap probe and the adaptability of microfluidic technology, MFIA demonstrated an exceptional detection limit (5 copies/μL) and specificity in the simultaneous detection of common diarrhea pathogens in clinical samples. Our approach addresses the limitations of current diagnostic techniques by offering a rapid (turn around time <1 h), cost-effective, easy design steps (universal flap design), and excellent detection performance method suitable for multiple applications. The validation of MFIA against the gold-standard PCR method using 150 actual clinical samples showed no statistical difference in the detection performance of the two methods, positioning it as a potential detection tool in pediatric diagnostic virology and public health surveillance. In conclusion, the MFIA method promises to transform pediatric infectious disease diagnostics and contribute significantly to global health efforts combating viral gastroenteritis.

Fluorescent and colorimetric dual-readout platform for tuberculosis point-of-care detection based on dual signal amplification strategy and quantum dot nanoprobe

Rapid and accurate diagnosis of tuberculosis (TB) is of great significance to control the spread of this devastating infectious disease. In this work, a sensitive and low-cost point-of-care testing (POCT) detection platform for TB was developed based on recombinase polymerase amplification (RPA)-catalytic hairpin assembly (CHA)-assisted dual signal amplification strategy. This platform could achieve homogeneous fluorescent and visual diagnosis of TB by using CdTe quantum dots (QDs) signal reporter. In the presence of target DNA (IS1081 gene fragment), RPA amplicons blocked by short oligonucleotide strands could trigger CHA signal amplification, leading to the Ag+ releasing from C-Ag+-C structure and the fluorescence quenching of CdTe QDs by the released Ag+. Furthermore, the detection performance of CdTe QDs modified by 3-mercaptopropionic acid (MPA) or thiomalic acid (TMA) (MPA-capped QDs and TMA-capped QDs) was systematically compared. Experimental results demonstrated that TMA-capped QDs exhibited better detection sensitivity due to their stronger interaction with Ag+. The limits of detection (LODs) of fluorescence and visual analysis were as low as 0.13 amol L-1 and 0.33 amol L-1. This method was successfully applied to the clinical sputum samples from 36 TB patients and 20 healthy individuals, and its quantitative results were highly consistent with those obtained by real-time fluorescent quantitative polymerase chain reaction (RT-qPCR). The proposed approach has the advantages of high sensitivity and specificity, simple operation and low cost, and is expected to be applied in clinical TB screening and diagnosis.

A Novel High-Throughput Sample-in-Result-Out Device for the Rapid Detection of Viral Nucleic Acids

Clustered regularly interspaced short palindromic repeats (CRISPR) molecular diagnostic technology is one of the most reliable diagnostic tools for infectious diseases due to its short reaction time, high sensitivity, and excellent specificity. However, compared with fluorescent polymerase chain reaction (PCR) technology, CRISPR molecular diagnostic technology lacks high-throughput automated instrumentation and standardized detection reagents for high sensitivity, limiting its large-scale clinical application. In this study, a high-throughput automated device was developed by combining reagent lyophilization, extraction-free technology, and a one-pot consumable system. This innovative approach enabled the rapid sample-in-result-out detection of 48 samples in 25 min and demonstrated high sensitivity and specificity for the qualitative analysis of clinical samples. The obtained results show that the detection limit of the designed system for African swine fever virus (ASFV) is 0.5 copies/μL. As a proof concept, a single-tube dual-target nucleic acid detection method was developed, achieving a detection limit of 5 copies/μL for the ORF1ab and N genes of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) within 45 min. The method is highly specific, reliable, and stable, providing a feasible solution for the clinical application of CRISPR nucleic acid detection technology.

One-pot diagnostic methods based on CRISPR/Cas and Argonaute nucleases: strategies and perspectives

CRISPR/Cas and Argonaute (Ago) proteins, which target specific nucleic acid sequences, can be applied as diagnostic tools. Despite high specificity and efficiency, achieving sensitive detection often necessitates a preamplification step that involves opening the lid and multistep operation, which may elevate the risk of contamination and prove inadequate for point-of-care testing. Hence, various one-pot detection strategies have been developed that enable preamplification and sensing in a single operation. We outline the challenges of one-pot detection with Cas and Ago proteins, present several main implementation strategies, and discuss future prospects. This review offers comprehensive insights into this vital field and explores potential improvements to detection methods that will be beneficial for human health.

Recent advances in the CRISPR/Cas system-based visual detection method

Currently, various infectious pathogens and bacterial toxins as well as heavy metal pollution pose severe threats to global environmental health and the socio-economic infrastructure. Therefore, there is a pressing need for rapid, sensitive, and convenient visual molecular detection methods. The rapidly evolving detection approach based on clustered regularly interspaced short palindromic repeats (CRISPR)/associated nucleases (Cas) has opened a new frontier in the field of molecular diagnostics. This paper reviews the development of visual detection methods in recent years based on different Cas and analyzes their advantages and disadvantages as well as the challenges of future research. Firstly, different CRISPR/Cas effectors and their working principles in the diagnosis of various diseases are briefly reviewed. Subsequently, the article focuses on the development of visual readout signals in point-of-care testing using laboratory-based CRISPR/Cas technology, including colorimetric, fluorescence, and lateral flow analysis. Finally, the challenges and prospects of visual detection methods based on CRISPR/Cas technology are discussed.

CRISPR for companion diagnostics in low-resource settings

New point-of-care tests (POCTs), which are especially useful in low-resource settings, are needed to expand screening capacity for diseases that cause significant mortality: tuberculosis, multiple cancers, and emerging infectious diseases. Recently, clustered regularly interspaced short palindromic repeats (CRISPR)-based diagnostic (CRISPR-Dx) assays have emerged as powerful and versatile alternatives to traditional nucleic acid tests, revealing a strong potential to meet this need for new POCTs. In this review, we discuss CRISPR-Dx assay techniques that have been or could be applied to develop POCTs, including techniques for sample processing, target amplification, multiplex assay design, and signal readout. This review also describes current and potential applications for POCTs in disease diagnosis and includes future opportunities and challenges for such tests. These tests need to advance beyond initial assay development efforts to broadly meet criteria for use in low-resource settings.

Split crRNA with CRISPR-Cas12a enabling highly sensitive and multiplexed detection of RNA and DNA

The CRISPR-Cas12a system has revolutionized nucleic acid testing (NAT) with its rapid and precise capabilities, yet it traditionally required RNA pre-amplification. Here we develop rapid fluorescence and lateral flow NAT assays utilizing a split Cas12a system (SCas12a), consisting of a Cas12a enzyme and a split crRNA. The SCas12a assay enables highly sensitive, amplification-free, and multiplexed detection of miRNAs and long RNAs without complex secondary structures. It can differentiate between mature miRNA and its precursor (pre-miRNA), a critical distinction for precise biomarker identification and cancer progression monitoring. The system's specificity is further highlighted by its ability to detect DNA and miRNA point mutations. Notably, the SCas12a system can quantify the miR-21 biomarker in plasma from cervical cancer patients and, when combined with RPA, detect HPV at attomole levels in clinical samples. Together, our work presents a simple and cost-effective SCas12a-based NAT platform for various diagnostic settings.

Phase transition-driven encapsulation of biomolecules using liquid metal with on-demand release for biomedical applications

Robust encapsulation and controllable release of biomolecules have wide biomedical applications ranging from biosensing, drug delivery to information storage. However, conventional biomolecule encapsulation strategies have limitations in complicated operations, optical instability, and difficulty in decapsulation. Here, we report a simple, robust, and solvent-free biomolecule encapsulation strategy based on gallium liquid metal featuring low-temperature phase transition, self-healing, high hermetic sealing, and intrinsic resistance to optical damage. We sandwiched the biomolecules with the solid gallium films followed by low-temperature welding of the films for direct sealing. The gallium can not only protect DNA and enzymes from various physical and chemical damages but also allow the on-demand release of biomolecules by applying vibration to break the liquid gallium. We demonstrated that a DNA-coded image file can be recovered with up to 99.9% sequence retention after an accelerated aging test. We also showed the practical applications of the controllable release of bioreagents in a one-pot RPA-CRISPR/Cas12a reaction for SARS-COV-2 screening with a low detection limit of 10 copies within 40 min. This work may facilitate the development of robust and stimuli-responsive biomolecule capsules by using low-melting metals for biotechnology.

Harnessing the evolving CRISPR/Cas9 for precision oncology

The Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Cas9 system, a groundbreaking innovation in genetic engineering, has revolutionized our approach to surmounting complex diseases, culminating in CASGEVY™ approved for sickle cell anemia. Derived from a microbial immune defense mechanism, CRISPR/Cas9, characterized as precision, maneuverability and universality in gene editing, has been harnessed as a versatile tool for precisely manipulating DNA in mammals. In the process of applying it to practice, the consecutive exploitation of novel orthologs and variants never ceases. It's conducive to understanding the essentialities of diseases, particularly cancer, which is crucial for diagnosis, prevention, and treatment. CRISPR/Cas9 is used not only to investigate tumorous genes functioning but also to model disparate cancers, providing valuable insights into tumor biology, resistance, and immune evasion. Upon cancer therapy, CRISPR/Cas9 is instrumental in developing individual and precise cancer therapies that can selectively activate or deactivate genes within tumor cells, aiming to cripple tumor growth and invasion and sensitize cancer cells to treatments. Furthermore, it facilitates the development of innovative treatments, enhancing the targeting efficiency of reprogrammed immune cells, exemplified by advancements in CAR-T regimen. Beyond therapy, it is a potent tool for screening susceptible genes, offering the possibility of intervening before the tumor initiative or progresses. However, despite its vast potential, the application of CRISPR/Cas9 in cancer research and therapy is accompanied by significant efficacy, efficiency, technical, and safety considerations. Escalating technology innovations are warranted to address these issues. The CRISPR/Cas9 system is revolutionizing cancer research and treatment, opening up new avenues for advancements in our understanding and management of cancers. The integration of this evolving technology into clinical practice promises a new era of precision oncology, with targeted, personalized, and potentially curative therapies for cancer patients.