Lab on a Chip最新文献

DNA methylation is a crucial epigenetic modification used as a biomarker for early cancer progression. However, existing methods for DNA methylation analysis are complex, time-consuming, and prone to DNA degradation. This work demonstrates selective capture of unmethylated DNAs using ZnO nanowires without chemical or biological modifications, thereby concentrating methylated DNA, particularly those with high methylation levels that can predict cancer risk. We observe varying affinities between methylated and unmethylated DNA on ZnO nanowires, which may be influenced by differences in hydrogen bonding strength, potentially related to the effects of methylation on DNA strand behavior, including self-aggregation and stretching inhibition. As a result, the nanowire-based microfluidic device effectively collects unmethylated DNA, leading to a significantly increased ratio of methylated to unmethylated DNA, particularly for collecting low-concentration methylated DNA. This simplified microfluidic device, composed of ZnO nanowires, enables direct separation of specific methylated DNA, offering a potential approach for DNA methylation mapping in clinical disease diagnostics.

Microfluidic droplet sorting has emerged as a powerful technique for a broad spectrum of biomedical applications ranging from single cell analysis to high-throughput drug screening, biomarker detection and tissue engineering. However, the controlled and reliable retrieval of selected droplets for further off-chip analysis and processing is a significant challenge in droplet sorting, particularly in high-throughput applications with low expected hit rates. In this study, we present a microfluidic platform capable of sorting and dispensing individual droplets with minimal loss rates. We demonstrate our direct transfer mechanism by placing selected droplets containing hybridoma cells into microwells, eliminating the need for manual and often lossy handling steps. Sorted droplets are dispensed via a novel 3D-printed dispensing nozzle, enabling precise and controlled placement of selected single droplets into individual wells without affecting the microfluidic sorting flow. The sorting and transfer process is monitored in real time, which provides feedback and quality control of the entire workflow. Our integrated microfluidic system holds great potential for applications requiring high-throughput droplet sorting with minimal sample loss and precise dispensing into microwells, such as screening for therapeutical antibodies or monoclonal cells.

Revealing how individual cells alter their secretions over time is crucial for understanding their responses to environmental changes. Key questions include: When do cells modify their functions and states? What transitions occur? Insights into the kinetic secretion trajectories of various cell types are essential for unraveling complex biological systems. This review highlights seven microfluidic technologies for time-resolved single-cell secretion analysis: 1. Microwell real-time electrical detection: uses microelectrodes for precise, cell-specific, real-time measurement of secreted molecules. 2. Microwell real-time optical detection: employs advanced optical systems for real-time, multiplexed monitoring of cellular secretions. 3. Microvalve real-time optical detection: dynamically analyzes secretions under controlled in situ stimuli, enabling detailed kinetic studies at the single-cell level. 4. Droplet real-time optical detection: provides superior throughput by generating droplets containing single cells and sensors for high-throughput screening. 5. Microwell time-barcoded optical detection: utilizes sequential barcoding techniques to facilitate scalable assays for tracking multiple secretions over time. 6. Microvalve time-barcoded optical detection: incorporates automated time-barcoding via micro-valves for robust and scalable analysis. 7. Microwell time-barcoded sequencing: captures and labels secretions for sequencing, enabling multidimensional analysis, though currently limited to a few time points and extended intervals. This review specifically addresses the challenges of achieving high-resolution timing measurements with short intervals while maintaining scalability for single-cell screening. Future advancements in microfluidic devices, integrating innovative barcoding technologies, advanced imaging technologies, artificial intelligence-powered decoding and analysis, and automations are anticipated to enable highly sensitive, scalable, high-throughput single-cell dynamic analysis. These developments hold great promise for deepening our understanding of biosystems by exploring single-cell timing responses on a larger scale.

Organs-on-chips (OoCs) have significantly advanced biomedical research by precisely reconstructing human microphysiological systems with biomimetic functions. However, achieving greater structural complexity of cell cultures on-chip for enhanced biological mimicry remains a challenge. To overcome these challenges, 3D bioprinting techniques can be used in directly building complex 3D cultures on chips, facilitating the in vitro engineering of organ-level models. Herein, we review the distinctive features of OoCs, along with the technical and biological challenges associated with replicating complex organ structures. We discuss recent bioprinting innovations that simplify the fabrication of OoCs while increasing their architectural complexity, leading to breakthroughs in the field and enabling the investigation of previously inaccessible biological problems. We highlight the challenges for the development of 3D bioprinted OoCs, concluding with a perspective on future directions aimed at facilitating their clinical translation.

Heterogeneities among tumor cells significantly contribute towards cancer progression and therapeutic inefficiency. Hence, understanding the nature of cancer through liquid biopsies and isolation of circulating tumor cells (CTCs) has gained considerable interest over the years. Microfluidics has emerged as one of the most popular platforms for performing liquid biopsy applications. Various label-free and labeling techniques using microfluidic platforms have been developed, the majority of which focus on CTC isolation from normal blood cells. However, sorting and profiling of various cell phenotypes present amongst those CTCs is equally important for prognostics and development of personalized therapies. In this review, firstly, we discuss the biophysical and biochemical heterogeneities associated with tumor cells and CTCs which contribute to cancer progression. Moreover, we discuss the recently developed microfluidic platforms for sorting and profiling of tumor cells and CTCs. These techniques are broadly classified into biophysical and biochemical phenotyping methods. Biophysical methods are further classified into mechanical and electrical phenotyping. While biochemical techniques have been categorized into surface antigen expressions, metabolism, and chemotaxis-based phenotyping methods. We also shed light on clinical studies performed with these platforms over the years and conclude with an outlook for the future development in this field.

Point-of-care testing (POCT) holds significant importance in the field of infectious disease prevention and control, as well as personalized precision medicine. The emerging microfluidics, capable of minimal reagent consumption, integration, and a high degree of automation, play a pivotal role in POCT. Centrifugal microfluidics, also termed lab-on-a-disc (LOAD), is a significant subfield of microfluidics that integrates crucial analytical steps onto a single chip, thereby optimizing the process and enabling high-throughput, automated analysis. By utilizing rotational mechanics to precisely control fluid dynamics without external pressure sources, centrifugal microfluidics facilitates swift operations ideal for urgent medical and field settings. This review provides a comprehensive overview of the latest advancements in centrifugal microfluidics for POCT, covering both theoretical principles and practical applications. We begin by introducing the fundamental operational principles, fluidic control mechanisms, and signal output detection methods. Subsequently, we delve into the typical applications of centrifugal microfluidic platforms in immunoassays, nucleic acid testing, antimicrobial susceptibility testing, and other tests. We also discuss the strengths and potential limitations of centrifugal microfluidic platforms, underscoring their transformative impact on traditional conventional procedures and their significant role in diagnostic practices.

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.

Cell cultures, organs-on-chip and microphysiological systems become increasingly relevant as in vitro models, e.g., in drug development, disease modelling, toxicology or cancer research. It has been underlined repeatedly that culture conditions and metabolic cues have a strong or even essential influence on the reproducibility and validity of such experiments but are often not appropriately measured or controlled. Here we review microsensor systems for cell metabolism for the continuous measurement of culture conditions in microfluidic and lab-on-chip platforms. We identify building blocks, features and essential advantages to underline the relevance of these systems and to derive appropriate requirements for development and practical use. We discuss different formats and geometries of cell culture, microfluidics and the resulting consequences for sensor placement, as the prerequisite for understanding the various approaches and classification of the systems. The major chemical and biosensors based on electrochemical and optical principles are discussed for general understanding and to contextualize current developments. We then review selected recent sensor systems with real-world implementations of sensing in cell cultures and organs-on-chip, employing a helpful characterization. That includes formats and cell models, microfluidic systems and sensor types applied in static and dynamic monitoring of 2D and 3D cell cultures, as well as single spheroids. We discuss notable advances, particularly with respect to sensor performance and the demonstration of long-term continuous measurements. We outline current approaches to system fabrication technologies, material choice, and interfacing, and comment on recent trends. Finally, we conclude with critical remarks on the current state of sensors in cell culture monitoring and identify avenues for future improvements for both developers and users of such systems, which will lead to better and more predictive in vitro models.

In the past decade, interest in nanoplasmonic structures has experienced significant growth, owing to rapid advancements in materials science and the evolution of novel nanofabrication techniques. The activities in the area are not only leading to remarkable progress in specific applications in photonics, but also permeating to and synergizing with other fields. This review delves into the symbiosis between nanoplasmonics and microfluidics, elucidating fundamental principles on nanophotonics centered on surface plasmon-polaritons, and key achievements arising from the intricate interplay between light and fluids at small scales. This review underscores the unparalleled capabilities of subwavelength plasmonic structures to manipulate light beyond the diffraction limit, concurrently serving as fluidic entities or synergistically combining with micro- and nanofluidic structures. Noteworthy phenomena, techniques and applications arising from this synergy are explored, including the manipulation of fluids at nanoscopic dimensions, the trapping of individual nanoscopic entities like molecules or nanoparticles, and the harnessing of light within a fluidic environment. Additionally, it discusses light-driven fabrication methodologies for microfluidic platforms and, contrariwise, the use of microfluidics in the fabrication of plasmonic nanostructures. Pondering future prospects, this review offers insights into potential future developments, particularly focusing on the integration of two-dimensional materials endowed with exceptional optical, structural and electrical properties, such as goldene and borophene, which enable higher carrier densities and higher plasmonic frequencies. Such advancements could catalyze innovations in diverse applications, including energy harvesting, advanced photothermal cancer therapies, and catalytic processes for hydrogen generation and CO₂ conversion.

X-ray-based methods are powerful tools for structural and chemical studies of materials and processes, particularly for performing time-resolved measurements. In this critical review, we highlight progress in the development of X-ray compatible microfluidic and millifluidic platforms that enable high temporal and spatial resolution X-ray analysis across the chemical and materials sciences. With a focus on liquid samples and suspensions, we first present the origins of microfluidic sample environments for X-ray analysis by discussing some alternative liquid sample holder and manipulator technologies. The bulk of the review is then dedicated to micro- and milli-fluidic devices designed for use in the three main areas of X-ray analysis: (1) scattering/diffraction, (2) spectroscopy, and (3) imaging. While most research to date has been performed at synchrotron radiation facilities, the recent progress made using commercial and laboratory-based X-ray instruments is then reviewed here for the first time. This final section presents the exciting possibility of performing in situ and operando X-ray analysis in the 'home' laboratory and transforming microfluidic and millifluidic X-ray analysis into a routine method in physical chemistry and materials research.