Lab on a Chip最新文献

We propose a novel contactless droplet manipulation strategy that combines electrostatic tweezers (ESTs) with lubricated slippery surfaces. Electrostatic induction causes the droplet to experience an electrostatic force, allowing it to move with the horizontal shift of the EST. Because both the EST and the slippery operating platform prepared by a femtosecond laser exhibit a strong binding effect on droplets, the EST droplet manipulation features significant flexibility, high precision, and can work under various operating conditions. The EST can manipulate droplets with a wide volume range (500 nL–1 mL), droplets hanging on tilted or even inverted surfaces, multiple droplets in parallel, corrosive droplets, low-surface-tension organic droplets (e.g., ethanol), and even droplets in a sealed space from the outside. The EST operation method is suitable for various slippery substrates prepared by femtosecond laser processing and can also be used to manipulate small solid spheres other than liquids. Additionally, a self-powered EST system is also designed without the need for high-voltage static electricity, allowing even fingers to serve as EST sources for droplet manipulation. The flexible and precise manipulation performance allows this technology to be applied in a variety of applications. For example, a new digital microfluidic (DMF) technology based on an EST array has been successfully validated and is expected to replace traditional electrowetting-on-dielectric technology in the future.

Organoids-on-a-chip exhibit significant potential for advancing disease modeling, drug screening, and precision medicine, largely due to their capacity to facilitate interactions among organoids. However, the influence of chip design on these interactions remains poorly understood, primarily due to our limited knowledge of the mediators of communication and the complexity of interaction dynamics. This study demonstrates that analyzing albumin secretion from liver organoids within an organoids-on-a-chip system can provide a measure of the interaction intensity among organoids, offering valuable insights into how chip design influences these interactions. Our findings reveal that the interaction dynamics of target organoids is primarily affected by the types of neighboring organoids positioned upstream. For instance, adipose organoids located upstream and adjacent to liver organoids considerably stimulate functional improvements in the liver organoids, whereas adipose organoids in other arrangements do not produce similar effects. Importantly, both theoretical and experimental evidence indicate that the interaction dynamics is independent of the physical distance between organoids. Instead, it can be adjusted by flow rate, well depth, introducing a vascular barrier, or the media volume within the system. However, it is crucial to note that the influence of these factors is not linear. Finally, the exosome was identified as one of key mediators of communication within the organoids-on-a-chip system.

Intrinsic biophysical and morphological features are essential for the label-free identification of different cell types. Indeed, apart from object size, density could represent a key parameter for single-cell analysis. However, the measurement of such a parameter is challenging. Therefore, we present a straightforward and versatile microfluidic chip. The densimeter-on-chip (DoC) measures single-cell mass densities thanks to a hydrodynamically induced sedimentation process inside the microchannel. In detail, in-flow buoyant components become more relevant than viscoelastic alignment forces, leading to precise in-flow sedimentation. DoC is based on precise three-dimensional cell alignment, followed by an abrupt change in cross-section to induce calibrated sedimentation. Based on the balance of acting forces and tracking the in-flow cell trajectory, we have developed a self-written mathematical model to precisely measure the single-cell densities of multiple cell types of any shape. Both cell velocity and fall length define the resulting cell density. The working range of object diameters for which density can be estimated is 0.75–22.5 μm. As result, the minimum measured density is 998 kg m⁻³ and a sensitivity of 0.001 can be obtained. Great agreement between the computational and the literature findings about red blood cells (∼1159 ± 29.5 kg m⁻³), lymphocytes (∼1073 ± 49 kg m⁻³) and neutrophils (∼1093 ± 27 kg m⁻³) is obtained without chip modification. Indeed, the computational error between the mean density values is ∼1%. Thereby, DoC as an easy-to-use and reproducible solution for label-free single-cell density measurement, provides a universal approach for characterizing a wide range of cell types, independently of their size and shape.

Organ-on-a-chip culture systems using human organ tissues provide invaluable preclinical insights into systemic functions in vitro. This study aimed to develop a novel human testicular tissue chip within a microfluidic device employing computer-aided design software and photolithography technology. Polydimethylsiloxane was used as the primary material to ensure marked gas permeability and no biotoxicity, enabling effective mimicry of the in vivo testicular microenvironment. This biochip preserved the structural integrity and cellular composition of human testicular tissue, as well as part of its functionality, over an extended period in vitro. Moreover, compared to traditional static culture methods, it more effectively maintained tissue viability and endocrine function. The chip maintained cellular components, histological morphology, and an ultrastructure similar to those in vivo. Notably, the addition of gonadotropins to the human testis tissue on the chip resulted in consistent and steady in vitro production of testosterone and inhibin B. Additionally, the chip displayed sensitivity to the reproductive toxicity of the chemotherapeutic drug busulfan. The results demonstrate the successful establishment of a novel human testicular tissue chip culture system, providing a novel in vitro approach enabling the exploration of human reproductive biology, reproductive pharmacology, toxicology, individual diagnosis, and treatment strategies.

Combining different “omics” approaches, such as genomics and proteomics, is necessary to generate a detailed and complete insight into microbiome comprehension. Proper sample collection and processing and accurate analytical methods are crucial in generating reliable data. We previously developed the ChipFilter device for proteomic analysis of microbial samples. We have shown that this device coupled to LC-MS/MS can successfully be used to identify microbial proteins. In the present work, we have developed our workflow to analyze concomitantly proteins and nucleic acids from the same sample. We performed lysis and proteolysis in the device using cultures of E. coli, B. subtilis, and S. cerevisiae. After peptide recovery for LC-MS/MS analysis, DNA from the same samples was recovered and successfully amplified by PCR for the 3 species. This workflow was further extended to a complex microbial mixture of known compositions. Protein analysis was carried out, enabling the identification of more than 5000 proteins. The recovered DNA was sequenced, performing comparable to DNA extracted with a commercial kit without proteolysis. Our results show that the ChipFilter device is suited to prepare samples for parallel proteomic and genomic analyses, which is particularly relevant in the case of low-abundant samples and drastically reduces sampling bias.

A novel microfluidic platform was designed to study the cellular architecture of endothelial cells (ECs) in an environment replicating the 3D organization and flow of blood vessels. In particular, the platform was constructed to investigate EC defects in slow-flow venous malformations (VMs) under varying shear stress and flow conditions. The platform featured a standard microtiter plate footprint containing 32 microfluidic units capable of replicating wall shear stress (WSS) in normal veins and enabling precise control of shear stress and flow directionality without the need for complex pumping systems. Using genetically engineered human umbilical vein endothelial cells (HUVECs) and induced pluripotent stem cell (iPSC)-derived ECs (iECs) to express the recurrent TIE2^L914F VM mutation we assessed responses on EC orientation and area, actin organization, and Golgi polarization to uni- and bidirectional flow and varying WSS. Comparison of control and TIE2^L914F expressing ECs showed differential cellular responses to flow and WSS in terms of cell shape elongation, orientation of F-actin, and Golgi polarization, indicating altered mechanosensory or mechanotransduction signaling pathways in the presence of the VM causative mutation. The data also revealed significant differences in how the primary and iPSC-derived iECs responded to flow. As a conclusion, the developed microfluidic platform allowed simulation of multiple flow conditions in a scalable and pumpless format. The design made it a desirable tool for studying different EC types as well as cellular changes in vascular disease. The platform should offer new opportunities for biomechanical research by providing a controlled environment to analyze the flow-dependent mechanosensory pathways in ECs.

Despite being a high-resolution separation technique, deterministic lateral displacement (DLD) technology is facing multiple challenges with regard to design, manufacture, and operation of pertinent devices. This work specifically aims at alleviating difficulties associated with design and manufacture of DLD chips. The process of design and production of computer-aided design (CAD) mask layout files that are typically required for computational modeling analysis, optimization, as well as for manufacturing DLD-based micro/nanofluidic chips is complex, time-consuming, and often necessitates a high level of expertise in the field. Herein, we report a universal framework to automate the process of designing DLD and producing layout CAD files for various systems spanning from simply a single DLD unit to complex parallelized DLD structures with/without additional upstream/downstream components, e.g., inlet filter, preload, collection channels, and through-wafer vias. In addition, to the best of our knowledge, for the first time, we adopt imprint lithography (IL) into fabrication process flow to define fine features of parallelized DLD arrays, while avoiding problems in connection with accessibility and cost of advanced photolithography tools. With regard to parallelized DLD architectures, we also report a new fabrication process flow aiming at mitigating the problems related to creating through-silicon vias at high yield. We demonstrate some use cases of our developed design and manufacture framework by designing and fabricating multiple devices to separate microspheres (0.6 μm and 1.3 μm) from aqueous media. We believe that our design automation package offers a user-friendly workflow, significantly alleviating the hurdles associated with design and optimization of DLD structures, while our fabrication process flow can provide an accessible solution to manufacturing micron- and submicron-scale DLD chips. These innovations should enable a larger community to adopt the DLD technology into their research, particularly for lab-on-a-chip applications.

Alzheimer's disease (AD) is the leading cause of dementia worldwide, and the development of early screening methods can address its significant health and social consequences. In this paper, we present a rotary-valve assisted paper-based immunoassay device (RAPID) for early screening of AD, featuring a highly integrated on-chip rotary micro-valve that enables fully automated and efficient detection of the AD biomarker (amyloid beta 42, Aβ42) in artificial plasma. The microfluidic paper-based analytical device (μPAD) of the RAPID pre-stores the required assay reagents on a μPAD and automatically controls the liquid flow through a single valve. Once the test sample is added, the test reagents are sequentially transferred to the test area in the order set by the enzyme-linked immunosorbent assay (ELISA) protocol. In addition, the RAPID can remotely control the operation of the μPAD valve via a micro-servomotor, quantify the signals generated, display the results, and wirelessly transmit the data to a smartphone. To calibrate the RAPID, we performed a sandwich ELISA for Aβ42 in artificial plasma, and obtained a low limit of detection (LOD) of 9.6 pg mL⁻¹, a coefficient of determination (COD) of 0.994, and an individual assay time of ∼30 minutes. In addition, we simulated 24 artificial samples to quantify Aβ42 protein concentrations in artificial plasma samples. The results show good consistency between the conventional ELISA and RAPID detection. The experimental results demonstrate that the RAPID is expected to promote further popularization of the screening of early-stage AD.

Sperm navigation through the complex microarchitecture of the fallopian tube is essential for successful fertilization. Spatiotemporal structural alteration due to folded epithelium or muscle contractions in the fallopian tube changes the geometry of the sperm pathways. The role of structural complexity in sperm navigational patterns has been investigated for single sperm cells but has not been fully addressed at the population level. Here, we studied the dynamics of the navigation of a bull sperm population through obstructed pathways mimicking the architecture of the female reproductive tract. We observed that slightly tapered barriers enhance navigation by 20% compared to straight pathway; however, tapered barriers with a 90° angle restrict sperm passage. We demonstrated sperm cooperation while passing through a tapered pathway in a low-viscosity medium under elevated shear rates. These findings propose a fresh perspective on how sperm move through the fallopian tube, suggesting that the convoluted pathways' shape influences sperm navigation locally.