Lateral flow nucleic acid biosensor for sensitive detection of microRNAs based on the dual amplification strategy of duplex-specific nuclease and hybridization chain reaction

Importance of DNA nanotechnology for DNA methyltransferases in biosensing assays

DNA methylation is the process by which specific bases on a DNA sequence acquire methyl groups under the catalytic action of DNA methyltransferases (DNMT). Abnormal changes in the function of DNMT are important markers for cancers and other diseases; therefore, the detection of DNMT and the selection of its inhibitors are critical to biomedical research and clinical practice. DNA molecules can undergo intermolecular assembly to produce functional aggregates because of their inherently stable physical and chemical properties and unique structures. Conventional DNMT detection methods are cumbersome and complicated processes; therefore, it is necessary to develop biosensing technology based on the assembly of DNA nanostructures to achieve rapid analysis, simple operation, and high sensitivity. The design of the relevant program has been employed in life science, anticancer drug screening, and clinical diagnostics. In this review, we explore how DNA assembly, including 2D techniques like hybridization chain reaction (HCR), rolling circle amplification (RCA), catalytic hairpin assembly (CHA), and exponential isothermal amplified strand displacement reaction (EXPAR), as well as 3D structures such as DNA tetrahedra, G-quadruplexes, DNA hydrogels, and DNA origami, enhances DNMT detection. We highlight the benefits of these DNA nanostructure-based biosensing technologies for clinical use and critically examine the challenges of standardizing these methods. We aim to provide reference values for the application of these techniques in DNMT analysis and early cancer diagnosis and treatment, and to alert researchers to challenges in clinical application.

Microfluidic-assisted integrated nucleic acid test strips for POCT

Numerous diseases have posed significant threats to public health, notably the global pandemic of COVID-19, resulting in widespread devastation due to its high infectivity and severity. The nucleic acid lateral flow assay (NALFA) addresses challenges of complexity, cost, and time associated with traditional assays, offering a reliable platform for rapid and precise nucleic acid target detection. NALFA is gaining prominence as a point-of-care testing (POCT) technique, thanks to its user-friendly operation and rapid results. Nevertheless, conventional NALFA relies on specialized technicians and involves labor-intensive steps like DNA extraction and PCR processes, impeding its efficiency. To overcome these limitations, integrating NALFA with microfluidic technology, widely employed in rapid field detection, holds promise. This review comprehensively outlines prevailing strategies for integrating NALFA, encompassing both research initiatives and commercial applications. Addressing the bottleneck of nucleic acid amplification as a rate-limiting step, the review delves into progress in amplification-free NALFA and highlights prevalent signal amplification techniques. Ultimately, the review outlines the future prospect of integrated NALFA development, capturing the technology's evolution and providing valuable insights for academic and commercial endeavors.

Biosensors, microfluidics systems and lateral flow assays for circulating microRNA detection: A review

MicroRNAs (miRNAs) are short RNA sequences found in eukaryotic cells and they are involved in several diseases pathogenesis including different types of cancers, metabolic and cardiovascular disorders. Thus, miRNAs circulating in serum, plasma, and other body fluids are employed as biomarkers for diagnostic and prognostic purposes and in assessment of drug response. Thus, various methods have been developed for detection of miRNAs including northern blotting, reverse transcriptase polymerase chain reaction (RT-PCR), next-generation sequencing, microarray, and isothermal amplification that are recognized as traditional methods. Considering the importance of early diagnosis and treatment of miRNAs-related diseases, development of simple, one-step, sensitive methods is of great interest. Nowadays developing technologies including lateral flow assay, biosensors (optical and electrochemical) and microfluidic systems which are simple fast responding, user-friendly, and are enabled with visible detection have gained considerable attention. This review briefly discusses miRNAs detection' methods, with a particular focus on lateral flow assay, biosensors, and microfluidic systems as novel and practical procedures.

Potential role of micro ribonucleic acids in screening for anal cancer in human papilloma virus and human immunodeficiency virus related malignancies

Despite advances in antiretroviral treatment (ART), human immunodeficiency virus (HIV) continues to be a major global public health issue owing to the increased mortality rates related to the prevalent oncogenic viruses among people living with HIV (PLWH). Human papillomavirus (HPV) is the most common sexually transmitted viral disease in both men and women worldwide. High-risk or oncogenic HPV types are associated with the development of HPV-related malignancies, including cervical, penile, and anal cancer, in addition to oral cancers. The incidence of anal squamous cell cancers is increasing among PLWH, necessitating the need for reliable screening methods in this population at risk. In fact, the currently used screening methods, including the Pap smear, are invasive and are neither sensitive nor specific. Investigators are interested in circulatory and tissue micro ribonucleic acids (miRNAs), as these small non-coding RNAs are ideal biomarkers for early detection and prognosis of cancer. Multiple miRNAs are deregulated during HIV and HPV infection and their deregulation contributes to the pathogenesis of disease. Here, we will review the molecular basis of HIV and HPV co-infections and focus on the pathogenesis and epidemiology of anal cancer in PLWH. The limitations of screening for anal cancer and the need for a reliable screening program that involves specific miRNAs with diagnostic and therapeutic values is also discussed.

Point-of-care diagnostics approaches for detection of lung cancer-associated circulating miRNAs

Circulating cell-free miRNAs (ccf-miRs) have gained significant interest as biomarkers for lung cancer (LC) diagnosis. However, the clinical application of ccf-miRs is mainly limited by time, cost, and expertise-related problems of existing detection strategies. Recently, the development of different point-of-care (POC) approaches offers useful on-site platforms, because these technologies have important features such as portability, rapid turnaround time, minimal sample requirement, and cost-effectiveness. In this review, we discuss different POC approaches for detecting ccf-miRs and highlight the utility of incorporating nanomaterials for enhanced biorecognition and signal transduction, further improving their diagnostic applicability in LC settings.

Duplex-specific nuclease signal amplification-based fluorescent lateral flow assay for the point-of-care detection of microRNAs

MiRNAs play important regulatory roles in numerous biological processes and serve as significant biomarkers for the development and prognosis of several diseases. Their unique characteristics, such as short size, high sequence homology among family members, low abundance, and easy degradability, have hindered their specific and highly sensitive detection. Herein, a duplex-specific nuclease (DSN)-assisted target recycling signal amplification-based fluorescent lateral flow assay was demonstrated for the point-of-care detection of cancer-related miRNA-21. In this assay, digoxin/biotin-labeled DNA probes were selectively cleaved by the DSN enzyme in the rounds of hybridization with the miRNA-21 target and cleavage cycle. Subsequently, the resulting mixture, containing the miRNA-21 target and intact and cleaved DNA probes, was loaded onto the lateral flow strip with digoxin antibody-conjugated quantum dot nanobeads and the streptavidin-coated test line. The increase in the proportion of cleaved DNA probes can induce a weakened response signal, which is directly associated with the amount of the miRNA target. Thus, highly sensitive quantification of miRNA-21 was achieved at a low limit of detection of 0.16 pM within 2 h of assay time. Assay specificity toward miRNA-21 was validated by testing several other miRNAs, including let-7b, let-7d, miRNA-141, and miRNA-200a. Moreover, the assay can quantify miRNA-21 spiked in human serum samples with acceptable recovery values, thus indicating its considerable clinical feasibility.

Extracellular Vesicles: Current Analytical Techniques for Detection and Quantification

Since their first observation, understanding the biology of extracellular vesicles (EV) has been an important and challenging field of study. They play a key role in the intercellular communication and are involved in important physiological and pathological functions. Therefore, EV are considered as potential biomarkers for diagnosis, prognosis, and monitoring the response to treatment in some diseases. In addition, due to their properties, EV may be used for therapeutic purposes. In the study of EV, three major points have to be addressed: 1. How to isolate EV from cell culture supernatant/biological fluids, 2. how to detect them, and 3. how to characterize and quantify. In this review, we focus on the last two questions and provide the main analytical techniques up-to-date for detection and profiling of EV. We critically analyze the advantages and disadvantages of each one, aimed to be of relevance for all researchers working on EV biology and their potential applications.

From Point-of-Care Testing to eHealth Diagnostic Devices (eDiagnostics)

Point-of-care devices were originally designed to allow medical testing at or near the point of care by health-care professionals. Some point-of-care devices allow medical self-testing at home but cannot fully cover the growing diagnostic needs of eHealth systems that are under development in many countries. A number of easy-to-use, network-connected diagnostic devices for self-testing are needed to allow remote monitoring of patients' health. This Outlook highlights the essential characteristics of diagnostic devices for eHealth settings and indicates point-of-care technologies that may lead to the development of new devices. It also describes the most representative examples of simple-to-use, point-of-care devices that have been used for analysis of untreated biological samples.

Ultrafast, universal and visual screening of dual genetically modified elements based on dual super PCR and a lateral flow biosensor

In this study, a cascade screening system has been developed combining Dual Super Polymerase Chain Reaction (DSPCR) with the universal Lateral Flow Biosensor (LFB) for the ultrafast, universal and visual screening of dual GM elements, taking P-35s × T-nos for example. In the design of DSPCR for universal screening, gene-specific forward primers were labelled with biotin and gene-specific reverse primers were tagged with Cy5 and digoxin, respectively. In 2.5-min, DSPCR effectively amplified the dual target fragments through our prototype facility. Then, through specific antigen-antibody binding, a universal lateral flow biosensor exported visually dual-amplified results simultaneously without cross contamination. After optimization, the detection limit allowed 0.05% GM maize, corresponding to nine copies in maize. The entire detection process could be achieved in 10 min without any large-scale instrumentation. This method may be useful for the ultrafast, universal and visual screening of dual GM elements (P-35s × T-nos) in GM crop lines and is expected to be of great promise for rapid GMO screening and point-of-care tests.

MicroRNA sensors based on gold nanoparticles

MicroRNAs (miRNAs) are small regulatory RNAs, the dysregulation of which has been associated with the progression of several human diseases, including cancer. Interestingly, these molecules can be used as biomarkers for early disease diagnosis and can be found in a variety of body fluids and tissue samples. However, their specific properties and very low concentrations make their detection rather challenging. In this regard, current detection methods are complex, cost-ineffective, and of limited application in point-of-care settings or resource-limited facilities. Recently, nanotechnology-based approaches have emerged as promising alternatives to conventional miRNA detection methods and paved the way for research towards sensitive, fast, and low-cost detection systems. In particular, due to their exceptional properties, the use of gold nanoparticles (AuNPs) has significantly improved the performance of miRNA biosensors. This review discusses the application of AuNPs in different miRNA sensor modalities, commenting on recently reported examples. A practical overview of each modality is provided, highlighting their future use in clinical diagnosis. Graphical abstract ᅟ.