Lab on a Chip最新文献

Pancreatic islets play a major role in glucose homeostasis as well as in diabetes, and islets-on-chip devices have been mainly developed using optical means for on-line monitoring. In contrast, no well-characterized electrophysiological platform for on-line analysis with unrivalled temporal resolution has been reported. Extracellular electrophysiology monitors two crucial parameters, islet β-cell activity and β-to-β-cell coupling, does not require chemical or genetic probes with inherent potential bias, is non-invasive and permits repetitive long-term monitoring. We have now developed and characterized a microfluidic islets-on-chip for combined electrophysiology (on-line) and hormone monitoring (off-line) with two chambers for concomitant monitoring. Fabrication of the device, based on commercial or easily manufacturable components, is within the reach of non-specialized laboratories. The chip permits convenient loading as well as long-term culture with comparable glucose kinetics and low shear stress in both chambers. An optimized flow rate did not alter islet β-cell electrical activity or coupling in response to glucose. Culturing for up to 8 days did not change islet survival as well as glucose-induced electrical or secretory kinetics of islet β-cells. The addition of a physiological amino acid mix, in the presence of elevated glucose, made a considerable change in the functional organisation of islet β-cell activity in terms of frequency and coupling, which explains the ensuing strong increase in insulin secretion. This device thus allows reliable long-term multiparametric on-line monitoring in two islet populations. The ease of fabrication, assembly and handling should permit widespread long-term on-line monitoring of islet activity in native micro-organs (e.g. controls/mutants), pseudo-islets or stem-cell-derived islet-like organoids.

We explore the capabilities of a microfluidic-based synthetic molecular communication (SMC) system for the transmission of physiological data within the human body. The system employs oscillating water droplets as a means of transmitting information through pressure variations. The validity of this approach for binary communications is validated through a combination of simulations and experiments. A case study focused on monitoring gastroesophageal reflux disease (GERD) has been considered. The prototype platform demonstrated the capacity to transmit both synthetic raw esophageal pH values and severity classifications (e.g. acid reflux) through oscillating droplets. This finding underscores the promise of SMC for real-time physiological monitoring, paving the way for enhanced disease diagnosis and personalized treatment in medicine. Despite the need for miniaturization to facilitate in vivo use, this research establishes a robust foundation for the development of microfluidic SMC devices for medical diagnostics and physiological monitoring.

The use of the intrinsic electrical properties of a single cell by broadband electrical impedance spectroscopy (EIS) as a label-free and non-invasive method to monitor cellular and intracellular features is an emerging field. Here, we present a novel EIS-based sheathless microfluidic platform with an integrated coplanar waveguide to probe the interior of a single cell. This platform allows for precise single-cell trapping by dielectrophoresis, hydrodynamic focusing, and sensing the electrical properties of the trapped single cell. We measured the impedance characteristics of a single Schizosaccharomyces pombe (fission) yeast cell by a single frequency sweep (30 kHz to 6GHz) in a stagnant sucrose solution using two-port scattering (S) parameters. The measurements revealed a clear distinction between the cytoplasm impedance of live versus dead cells at 3 GHz. This platform could provide real-time monitoring of cellular electrical responses to chemical and physical antagonists for diagnostic purposes.

We describe a model system for vascular-cell culture where recirculating fluid flow in standard culture plates is generated by gravity using a combination of platform tilt and rotation (nutation). Placed inside a cell-culture incubator, variable nutation speeds provide pulsatile shear stresses to vascular cells within the physiological range. The effect of these stresses on cells is demonstrated here using standard laboratory techniques such as immunofluorescent staining, immunoblot, and supernatant analyses. This gravity-driven model framework is well-suited for assessing dynamic conditions for mono- and co-cultures. In addition, the modular design and the use of off-the-shelf components make the system economical and scalable.

Correction for ‘Acoustic modulation and non-contact atomization of droplets based on the Fabry–Pérot resonator’ by Jingjun Li et al., Lab Chip, 2024, 24, 2418–2427, https://doi.org/10.1039/D4LC00071D.

We report methods that improve the manipulation of magnetic beads using digital microfluidics (DMF) that can enhance the performance of single molecule array (Simoa) digital protein assays in miniaturized analytical systems. Despite significant clinical and biomedical applications for digital protein detection, the development of miniaturized Simoa systems has been limited by the requirements for use of large sample volumes (∼100 μL) and low numbers of beads (∼5000) for high sensitivity tests. To address these challenges, we improved the integration of DMF with Simoa-based assays by developing strategies for loading mixtures of sample and beads into DMF networks using methods relying on either virtual channels or small liquid segments that were applied either in parallel or in a stepwise manner. We have also demonstrated a dedicated densifying electrode technique that captures low numbers of beads within a droplet, allowing high bead retention with minimal residual volumes of liquid. Based on these improvements, we optimized the front-end assay processing of beads using DMF and demonstrated a method to detect tumor necrosis factor α (TNF-α) by Simoa that showed equivalent performance to a microtitre plate assay. The new strategies described here form a step toward integrating DMF and Simoa for a wide range of applications.

The incidence of inflammatory bowel disease among the elderly has significantly risen in recent years, posing a growing socioeconomic burden to aging societies. Moreover, non-gastrointestinal diseases, also prevalent in this demographic, have been linked to intestinal barrier dysfunction, thus highlighting the importance of investigating aged-mediated changes within the human gut. While gastrointestinal pathology often involves an impaired gut barrier, the impact of aging on the human gastrointestinal barrier function remains unclear. To explore the effect of senescence, a key hallmark of aging, on gut barrier integrity, we established and evaluated an in vitro gut-on-a-chip model tailored to investigate barrier changes by the integration of an impedance sensor. Here, a microfluidic gut-on-a-chip system containing integrated membrane-based electrode microarrays is used to non-invasively monitor epithelial barrier formation and senescence-mediated changes in barrier integrity upon treating Caco-2 cells with 0.8 μg mL⁻¹ doxorubicin (DXR), a chemotherapeutic which induces cell cycle arrest. Results of our microfluidic human gut model reveal a DXR-mediated increase in impedance and cell hypertrophy as well as overexpression of p21, and CCL2, indicative of a senescent phenotype. Combined with the integrated electrodes, monitoring ∼57% of the cultivation area in situ and non-invasively, the developed chip-based senescent-gut model is ideally suited to study age-related malfunctions in barrier integrity.

Cell analysis plays an important role in disease diagnosis. However, many characterisation techniques are labour intensive, expensive and time-consuming. Impedance and dielectric spectroscopy (IDS) offers a new approach by using varying electrical current and electric field propagation responses to probe cell physiology. This review aims to explore the theoretical foundations, practical applications, and advancements in IDS for single-cell analysis, particularly when integrated with microfluidic technologies. It highlights recent developments in electrode configurations, calibration techniques, and data analysis methodologies, emphasising their importance in enhancing sensitivity and selectivity. The review identifies key trends, including the shift towards high-throughput and precise single-cell analysis, and discusses the challenges and potential solutions in this field. The implications of these findings suggest significant near-future advances in biomedical research, diagnostics, and therapeutic monitoring. This paper serves as a comprehensive reference for researchers in different fields to make a bridge between theoretical research and practical implementation in single-cell analysis.

Platforms capable of selective single-cell capture and enclosure in a fluidically isolated volume for subsequent analysis are crucial for unmasking cellular heterogeneity. Our research group has previously reported an approach that employs wireless bipolar electrodes (BPEs) to facilitate individual isolation of cells in large arrays of pico- to nanoliter scale chambers by dielectrophoresis (DEP). This device was leveraged for a single-cell enzymatic assay and the isolation of circulating tumor cells (CTCs) from patient-derived blood samples, which takes advantage of the selectivity of DEP. However, alignment of BPEs to the microchamber openings is nontrivial, and augmentation of the array dimensions accumulates alignment error, thereby disrupting the uniformity of cell capture across the device. Thus, tolerance-forgiving designs that are simultaneously expandable are in demand. To address this demand, we present an approach that combines BPEs with insulator DEP (iDEP) to drastically expand alignment tolerance. This iDEP-BPE device offers a vertical tolerance (the distance the BPE is recessed within each microchamber) of 80 μm while the horizontal tolerance is nearly infinite. Further, the iDEP-BPE device decreases the exposure of cells to electrode surfaces and reactive oxygen species, thereby preserving their viability. Finally, this iDEP approach can be carried out with BPEs that are easy to fabricate, lacking features that require high-resolution lithography. These advancements potentiate the broad adoption of the iDEP-BPE approach for selective single-cell capture and on-chip analysis and potentiate its commercialization upon deployment of appropriate thermoplastic materials.

Preclinical evaluation of anticancer drug efficacy utilizes 2D cell culture systems, tumoroids or experimental animal models, but it suffers from limitations such as inaccurate simulation of tumor microenvironments in living tumors, difficulty in regional analysis, and low throughput. Therefore, in this study, we developed a system named tumor-microenvironment-on-chip (TMoC) comprising a 3D dynamic tumor tissue culture system, which recreated diverse and heterogeneous cellular tumor microenvironments. In addition to the culture with a dynamic circulation, TMoC allowed users to perform real-time regional analysis, independently assessing the drug response from the normoxic area to the hypoxic area in a gradient manner. Through cell composition analysis and gene analysis, we proved that TMoC has a tumor environment with close resemblance to the original tumor environment. By comparing 15 drug testing results with animal experiments, we proved that TMoC is 93% consistent with the response results of animal experiments. In addition, we confirmed that either mouse- or patient-derived tumor cell lines can be cultured and tested in TMoC, indicating its immense potential for all aspects of preclinical drug evaluation.