Lab on a Chip最新文献

Inertial microfluidics provides a label-free strategy for isolating circulating tumor cells (CTCs) from blood by exploiting size-dependent lateral migration in microchannels. However, straight-channel devices are often optimized using the final equilibrium position, even though target-cell loss can arise from incomplete or poorly reproducible migration before outlet collection. Here, we show that heteroclinic orbit engagement provides a predictive design criterion for improving CTC scale separation in a rectangular co-flow inertial microchannel. A computational model predicted size-dependent heteroclinic orbits and lateral migration velocities, which were experimentally validated using beads under controlled inlet flow-split conditions. Increasing buffer confinement shifted the sample-buffer interface closer to the sidewall, promoted earlier orbit engagement, improved agreement between measured and simulated velocity profiles, and reduced upstream trajectory variability. Larger CTC scale particles engaged their orbits earlier and migrated more reproducibly, while smaller white blood cell (WBC) scale particles remained laterally displaced from the larger particle focusing region. Biological validation with PANC1 and A549 cells showed that the 1 : 6 : 1 flow-split configuration increased separation efficiency to 99.9 ± 0.2% for PANC1 and maintained high separation efficiency of 99.2 ± 0.9% for A549 cells, although its effect on total recovery was cell line dependent. In an intraductal papillary mucinous neoplasm (IPMN) patient sample, representing a premalignant pancreatic lesion that may progress to invasive pancreatic ductal adenocarcinoma (PDAC), CTC target outlet partitioning was 67% under 1 : 1 : 1 and 100% under 1 : 6 : 1, within the limits of the detected cell numbers. These results establish orbit engagement as a mechanistic design principle for improving clinically relevant CTC enrichment without changing device geometry, total flow rate, or labeling strategy.

Timely and accurate nucleic acid extraction is a critical bottleneck in point-of-care (POC) molecular diagnostics, particularly for low-abundance cell-free nucleic acids (DNA, RNA, miRNA) in plasma. We present a fully finger-actuated microfluidic device for power-free, pipette-free, nucleic acid extraction. The prototype device integrates finger-actuated valves, pump and blister reagent storage, enabling a complete, intuitive, "sample-to-eluate" workflow, including lysis, binding, washing and elution via manual actuation in approximately 35 minutes. The device operation was benchmarked against a commercial magnetic bead-based manual benchtop and an automated robotic workflow. In DNA-spiked aqueous samples (5-20 ng mL^-1), the device demonstrated recoveries of 84.6%, against 90.7% on the bench. Optimisation of magnetic bead volume identified 50 μL as the threshold for maximal recovery while minimising reagent consumption. Recovery from human pooled plasma samples were found to be on average 18, 62, and 552% higher than that obtained with the control bench extraction on initial sample volumes of 100, 75 and 50 μL, respectively. Coefficient of variation (CV%) for all techniques remained within reported laboratory ranges (20-80%). The device's clinical utility was piloted using patient samples positive for cytomegalovirus (CMV), monkeypox virus (MPXV) or chikungunya (CHIKV). The device achieved successful qPCR amplification for all targets, with viral DNA Cq values within as little as 0.3 cycles of the standard protocol. This instrument-free, manual circulating nucleic acid extraction tool could help bridge the gap between lateral flow based nucleic acid amplification technologies and real-world decentralised diagnostics, offering a scalable solution for infectious disease management in resource-limited settings.

An immune-competent, metabolically active gut-liver microphysiological platform (iGLoC) was engineered to investigate the pharmacokinetics, metabolism, hepatotoxicity, and drug-drug interaction (DDI) liabilities of the oral CDK4/6 inhibitor abemaciclib. The system integrates a mucus-secreting Caco-2/HT-29 intestinal epithelium co-cultured with THP-1-derived macrophages and 3D HepG2 spheroids in interconnected PMMA/PDMS microfluidic chips linked by a controlled-flow bridging channel. Intestinal barrier morphology, tight-junction integrity, transepithelial electrical resistance, P-glycoprotein transport, and paracellular permeability were functionally validated, while hepatic spheroids exhibited stable albumin and urea secretion and pharmacologically inducible CYP3A4 activity relative to 2D HepG2 monolayers, while remaining less CYP3A4-competent than primary hepatocytes. Following apical dosing with abemaciclib, serial sampling from apical, basolateral, and hepatic chambers combined with a validated UPLC-MS/MS assay enabled time-resolved quantification of parent drug and major metabolites (M2, M20). The platform reproduced an oral-like disposition profile characterized by luminal depletion, a transient basolateral peak, and delayed hepatic appearance, along with formation of clinically relevant metabolites. Pre-treatment with rifampicin (CYP3A4/P-gp inducer) or clarithromycin (CYP3A4/P-gp inhibitor) and induction of colitis-like injury with dextran sulfate sodium generated distinct, mechanistically consistent alterations in intestinal permeability, metabolite output, and hepatic exposure that mirrored reported clinical DDIs and inflammation-associated variability. Abemaciclib also elicited concentration-dependent hepatocellular injury and modulation of gut-immune cytokine responses at clinically relevant levels. iGLoC innovates through immune-competent gut-liver integration under flow, quantitative clinical PK validation for abemaciclib, and mechanistic resolution of CYP3A4/P-gp DDIs and inflammation effects. Collectively, these data demonstrate that iGLoC represents a human-relevant organ-on-a-chip platform capable of evaluating oral bioavailability, first-pass metabolism, metabolite formation, hepatotoxicity, and drug interaction potential. The system shows promise for preclinical assessment of small-molecule therapeutics, including those used in precision oncology applications.

Label-free tracking of adherent cell migration could enable important insights into biological processes such as tissue repair, inflammatory response, or cancer progression. Nevertheless, visualizing unlabeled animal cells using optical microscopy remains challenging due to low contrast as well as frequent changes in cell shape and number. A promising alternative uses electrical capacitance measurements, which are sensitive to cell adhesion to electrode surfaces. However, prior examples often utilized electrodes with areas larger than single cells, resulting in averaged readouts over multiple cells. Here, we demonstrate label-free, live-cell tracking using a capacitance sensor array with more than 1 million pixels on a 10 micron pitch across an area larger than 1 square centimeter. We show that single cell morphology can be clearly segmented and used to reconstruct migration and proliferation dynamics using optical flow. We further track the spreading of multicellular spheroids, revealing fast-moving peripheral regions led by a collective leader cell "front". Finally, we demonstrate label-free imaging of millimeter-scale honeycomb-shaped tissues without the multi-image stitching often required for conventional microscopy. We utilize mutual capacitance measurements with electrically-programmable electrode spacing to map topographical features of these engineered tissues. Overall, CMOS capacitance imaging arrays enable label-free imaging spanning from single cells to large tissues, in a portable and scalable format for settings where optical microscopy may be difficult to access.

Human cardiac and neuronal stem cell-derived spheroids and organoids are emerging models for drug discovery and drug safety studies. Their electrical properties are frequently investigated by means of multielectrode arrays (MEAs). However, it is difficult to establish adequate electrode contacts between planar MEAs and these round, 3D cell models. Contractions of cardiac 3D models and movement artefacts during the application of test solutions can also disrupt the recordings. As a solution, we present a microfluidics device (hereinafter referred to as SphereChip) that enables quick and stable attachment of free-floating spherical cell models such as cardiospheres, cardioids and neurospheres to conventional planar MEAs. The device reduces motion artifacts and enables complete solution exchange. It was successfully used with two different MEA designs for field potential measurements and simultaneous imaging using fluorescent probes on small cardio- and neurospheres (diameter 300 to 500 μm) and larger cardioids (800 to 900 μm). We observed concentration-dependent prolongation of action and field potentials of cardiospheres by the potassium channel (Kv1.11) inhibitors E4031 and dofetilide. In neurospheres, application of a potassium channel (Kv7.2/7.3) activator ML213 reduced spiking and bursting. We present these results as proof of concept for the microfluidics device as a means to enable organ-on-a-chip studies combining field potential measurements with simultaneous imaging on spherical cell models using planar MEAs. The method is applicable to different MEA formats and holds promise as a workable platform for drug testing and toxicity studies.

High-performance liquid handling is essential for a wide range of experiments. Previously, we introduced the Surface Patterned Omniphobic Tiles (SPOTs) platform, which enables manipulation of hundreds to thousands of independent experiments without costly equipment or excessive consumable expenses. However, the SPOTs platform uses a custom coating that requires a chemical synthesis step. This coating is also easily damaged by handling and requires careful manipulation, making it challenging to transport and interface the platform with existing well plates. To overcome these challenges, here we introduce the EZ-SPOTs platform which can be created in an hour with common fabrication tools and three components: glass, a phobic coating, and plastic. EZ-SPOTs preserve many of the SPOTs platform's strengths including ease of use, the ability to handle a wide range of volumes, and scalability, but by adopting a robust, abrasion-resistant coating, EZ-SPOTs devices can be reused. Additionally, this improved robustness enables the platform to address the "chip-to-lab" obstacle by directly interfacing with 96-well plates. Here, we describe the fabrication of EZ-SPOTs and showcase how devices can be reused to test many isolates for antimicrobial susceptibility. These results quantitatively match current gold-standard assays, and the increased throughput provides substantially more information than standard approaches.

Microphysiological systems (MPS) can improve intestinal epithelial modelling by combining 3D topographical cues, extracellular matrix mechanics and controlled apical-basal access. We present the EnView system, an imaging-compatible microphysiological platform configured to integrate human colon-inspired crypt-scale topography, tunable matrix stiffness and independent perfusion of apical/luminal and basal/stromal compartments. Crypt-like structures were molded in an interpenetrating polyacrylamide/collagen type I hydrogel, generating soft and stiff matrices with bulk stiffness values of 3.8 ± 1.8 kPa and 26.2 ± 8.4 kPa. Molecular transport through the hydrogel was characterized using FITC-dextrans of increasing molecular weight, and the experimentally derived diffusion coefficients were implemented in a numerical diffusion model to estimate the time required for soluble mediators to reach defined regions of the epithelial interface. Human colonic epithelial Caco-2 cells were cultured under continuous microfluidic perfusion for up to 21 days. Cells colonized the patterned surface, formed polarized epithelial monolayers and displayed stiffness-dependent morphology, with a more columnar organization on softer matrices highlighting the importance of matrix stiffness on cell morphology. Relative to standard 2D Transwell® conditions, these cultures exhibited increased gene expression of enterocyte markers such as FABP1 (fatty acid binding protein-1), ALPI (intestinal alkaline phosphatase), KRT20 (cytokeratin-20) and VIL1 (villin-1), indicating that the EnView environment supports better epithelial polarization and maturation-associated features compared with conventional Transwell® culture. Basal/stromal TNF-α stimulation induced an apical/luminal measurable epithelial IL8 secretion, demonstrating the capacity of the system for basal stimulation and apical sampling. Our results show the relevance of considering matrix stiffness when modelling the human colon epithelium. This innovative MPS, recapitulating 3D topography, tunable matrix stiffness and continuous microfluidic perfusion, represents a powerful platform for long term culture and in situ imaging of epithelial constructs enabled by active microfluidic control of the apical/luminal and basal/stromal compartments.

We report a smartphone-based microfluidic platform for automated nitrite determination using a paper colourimetric assay. The system combines a V-shaped microfluidic paper-based analytical device (μPAD), a wireless electronic module for capacitive flow monitoring and thermal actuation, and a custom Android application that coordinates the measurement sequence and processes the captured image. Fluid arrival at the sensing zone is identified from changes in capacitance, which trigger the heating step required to collapse a NIPAM-based hydrogel reservoir and release sulfanilic acid from the hydrogel reservoir. Images are acquired under ambient lighting conditions and analysed by an image-processing algorithm that includes circle detection, saturation-value (SV)-based pixel selection, and colour correction using in-frame black and white references. Calibration with standard nitrite solutions showed that the platform achieved a limit of detection (LOD) of 7.63 × 10^-6 M (0.35 mg L^-1 as NO₂^-) after colour correction, improving by about 17% with respect to the uncorrected response. The platform also showed good repeatability (CV < 6% at 10^-4 M) and consistent behaviour when tested with two different smartphones and several lighting conditions. Analysis of tap water and marine samples gave results in agreement with the reference method at the 95% confidence level. The platform combines automated fluid handling, thermally triggered reagent release, and adaptive image-based quantification in a portable format for nitrite analysis outside the laboratory.

Paper-based analytical devices (PADs) are attractive for point-of-need water analysis because of their low cost and operational simplicity. However, slow fluid transport often limits their analytical throughput. Here, we report a layer-by-layer PAD incorporating controlled interfacial gaps to enhance capillary-driven transport for the determination of dissolved inorganic carbon (DIC) in water. The device employs distance-based colorimetric detection using an acid-base system with bromocresol green (BCG) and was benchmarked against a laminated configuration fabricated from the same Whatman grade 4 paper. The layer-by-layer architecture reduced the colorimetric response time from 18 to 2.5 min while achieving limits of detection and quantification of 0.30 and 0.92 mg L^-1, respectively. Analysis of bottled mineral water samples showed good agreement with a reference potentiometric titration method, with relative errors below 7%. These results demonstrate that controlled interfacial engineering can be effectively integrated into distance-based PADs to accelerate analysis without modifying the sensing chemistry, providing a simple and low-cost approach for rapid on-site DIC determination.