Lab on a Chip最新文献

A significant challenge in the treatment of central nervous system (CNS) disorders is represented by the presence of the blood–brain barrier (BBB), a highly selective membrane that regulates molecular transport and restricts the passage of pathogens and therapeutic compounds. Traditional in vivo models are constrained by high costs, lengthy experimental timelines, ethical concerns, and interspecies variations. In vitro models, particularly microfluidic BBB-on-a-chip devices, have been developed to address these limitations. These advanced models aim to more accurately replicate human BBB conditions by incorporating human cells and physiological flow dynamics. In this framework, here we developed an innovative microfluidic system that integrates thin-film electrodes for non-invasive, real-time monitoring of BBB integrity using electrochemical impedance spectroscopy (EIS). EIS measurements showed frequency-dependent impedance changes, indicating BBB integrity and distinguishing well-formed from non-mature barriers. The data from EIS monitoring was confirmed by permeability assays performed with a fluorescence tracer. The model incorporates human endothelial cells in a vessel-like arrangement to mimic the vascular component and three-dimensional cell distribution of human astrocytes and microglia to simulate the parenchymal compartment. By modeling the BBB-on-a-chip with an equivalent circuit, a more accurate trans-endothelial electrical resistance (TEER) value was extracted. The device demonstrated successful BBB formation and maturation, confirmed through live/dead assays, immunofluorescence and permeability assays. Computational fluid dynamics (CFD) simulations confirmed that the device mimics in vivo shear stress conditions. Drug crossing assessment was performed with two chemotherapy drugs: doxorubicin, with a known poor BBB penetration, and temozolomide, conversely a specific drug for CNS disorders and able to cross the BBB, to validate the model predictive capability for drug crossing behavior. The proposed sensorized microfluidic device represents a significant advancement in BBB modeling, offering a versatile platform for CNS drug development, disease modeling, and personalized medicine.

Liver cancer is a significant global contributor to cancer-related mortality. Despite available targeted therapies, resistance to tyrosine kinase inhibitors (TKIs) like sorafenib and lenvatinib poses a formidable challenge. The tumor microenvironment (TME), inhabited by cancer-associated fibroblasts (CAFs), profoundly influences this resistance. To uncover the mechanisms, a 3D microfluidic chip replicating liver architecture was fabricated to probe the intricate mechanisms of TKI resistance. The chip design mirrors the hexagonal structure of liver lobules, situating liver cancer cells at the core, encircled by fibroblasts, with rigorous assessments confirming biocompatibility and consistent cell growth. After determining the IC₅₀ values of sorafenib and lenvatinib in 2D co-culture, a transwell setup revealed drug resistance development in co-cultured cells. Within the 3D microfluidic chip, live/dead assays highlighted elevated viability under drug exposure, emphasizing fibroblast-driven drug resistance. The study identifies AHSG and CLEC3B as potential mediators of drug resistance in co-culture, significantly upregulated in the co-cultured medium. Functional tests confirmed their roles, as introducing recombinant AHSG and CLEC3B enhanced liver cancer cell resistance to sorafenib and lenvatinib in both 2D and 3D scenarios. In conclusion, by replicating the complex TME using microfluidic technology, this study sheds light on the roles of AHSG and CLEC3B as well as possible approaches for improving the effectiveness of liver cancer treatment.

Regulation of protein mobility is a fundamental aspect of cellular processes. In this study, we examined the impact of DNA methylation on the diffusion of nucleoid associated protein Hfq. This protein is one of the most abundant proteins that shapes the bacterial chromosome and is involved in several aspects of nucleic acid metabolism. Fluorescence microscopy was employed to monitor the movement of Hfq along double-stranded DNA, which was stretched due to confinement within a nanofluidic channel. The mobility of Hfq is significantly influenced by DNA methylation. Our results underscore the importance of bacterial epigenetic modifications in governing the movement of nucleoid associated proteins such as Hfq. Increased levels of methylation result in enhanced binding affinity, which in turn slows down the diffusion of Hfq on DNA. The reported control of protein mobility by DNA methylation has potential implications for the mechanisms involved in target DNA search processes and dynamic modelling of the bacterial chromosome.

We report on the use of a microfluidic antisolvent crystallization method to investigate the effect of solution volume on the chiral symmetry breaking (CSB) phenomena of enantiomeric sodium chlorate crystals. The utilization of a microfluidic device is capable of periodically producing emulsion droplets of uniform size and facilitates the quantitative analysis and visualization of crystallization phenomena occurring within the individual emulsions immersed in an oil continuous medium (i.e., dodecane). To promote nucleation and crystallization, a small amount of an antisolvent (i.e., ethanol) is introduced into the continuous phase. We observe that 100% CSB occurs within a certain critical emulsion volume. Beyond this critical volume, the probability of forming two different enantiomeric crystal particles increases. This solution volume-dependent CSB phenomenon can be attributed to the rapid depletion of surrounding molecules by spontaneous crystal growth after the formation of the initial nucleus within the critical volume, thereby suppressing further primary nucleation.

Paper-based microfluidic devices offer an ideal platform for biological and environmental detection because they are low-cost, small, disposable, and fill by natural capillary action. In this tutorial review, we discuss the surface modification of paper-based microfluidic devices with functional polymers using the initiated chemical vapor deposition (iCVD) process. The iCVD process is solventless and therefore ideal for coating cellulose paper because there are no surface tension effects or solvent compatibility issues. The process can also be scaled up for roll-to-roll manufacturing. The chemical functionality of the iCVD coating can be tuned by varying the monomer and the structure of the coating can be tuned by varying the processing parameters.

Microfluidics provides unique opportunities for the high throughput selection of motile sperm with improved DNA integrity for assisted reproductive technologies (ARTs). Here, through a parametric study on dimensions and geometrical angles, a butterfly-shaped chip (BSC) is presented to isolate sperm with high progressive motility and intact DNA at a separation rate of 1125 sperm per minute. Using finite element simulations, the flow field and shear rates in the device were optimized to leverage the inherent motility characteristics of sperm for maximum selection throughput. The device incorporates a triple selection mechanism in series, initially activating sperm rheotaxis by rotation against the semen flow, penetrating the counter buffer flow and swimming against the direction of the buffer flow, leaving dead cells and debris behind, and subsequently leveraging boundary-following behavior to direct progressively motile sperm to swim along the walls and reach the device outlet. The device selects over 4.1 million sperm per mL within 20 minutes, with 29.2%, 68.2%, and 57.3% improvement in total motility, DNA integrity, and velocity parameter (VCL), as compared with the conventional swim-up method, respectively. Overall, the performance of the device to separate sperm with approximately 95.9% total motility, 97.8% viability, and 96.6% DNA integrity at high concentrations demonstrates its potential for enhancing the efficiency of conventional treatment methods.