BSEO-Semiautomatic Method for Determination of Oil Recovery with Nanofluids in Microfluidic Devices.

Microfluidic models have become essential instruments for studying enhanced oil recovery techniques through fluid and chemical injection into micromodels to observe interactions with pore structures and resident fluids. The widespread use of cost-effective lab-on-a-chip devices, known for efficient data extraction and minimal reagent usage, has driven demand for efficient data management methods crucial for high-performance data and image analyses. This article introduces a semiautomatic method for calculating oil recovery in polymeric nanofluid flooding experiments based on the background subtraction (BSEO). It employs the background subtraction technique, generating a foreground binary mask to detect injected fluids represented as pixel areas. The pixel difference is then compared to a threshold value to determine whether the given pixel is foreground or background. Moreover, the proposed method compares its performance with two other representative methods: the ground truth (manual segmentation) and Fiji-ImageJ software. The experiments yielded promising results. Low values of mean-squared error (MSE), mean absolute error (MAE), and root-mean-squared error (RMSE) indicate minimal prediction errors, while a substantial coefficient of determination (R2) of 98% highlights the strong correlation between the method's predictions and the observed outcomes. In conclusion, the presented method emphasizes the viability of BSEO as a robust alternative, offering the advantages of reduced computational resource usage and faster processing times.

Microdevices for cancer stem cell culture as a predictive chemotherapeutic response platform.

Microfluidic platforms for clinical use are a promising translational strategy for cancer research specially for drug screening. Identifying cancer stem cells (CSC) using sphere culture techniques in microfluidic devices (MDs) showed to be better reproducing physiological responses than other in vitro models and allow the optimization of samples and reagents. We evaluated individual sphere proliferation and stemness toward chemotherapeutic treatment (CT) with doxorubicin and cisplatin in bladder cancer cell lines (MB49-I and J82) cultured in MDs used as CSC treatment response platform. Our results confirm the usefulness of this device to evaluate the CT effect in sphere-forming efficiency, size, and growth rate from individual spheres within MDs and robust information comparable to conventional culture plates was obtained. The expression of pluripotency genetic markers (Oct4, Sox2, Nanog, and CD44) could be analyzed by qPCR and immunofluorescence in spheres growing directly in MDs. MDs are a suitable platform for sphere isolation from tumor samples and can provide information about CT response. Microfluidic-based CSC studies could provide information about treatment response of cancer patients from small samples and can be a promising tool for CSC-targeted specific treatment with potential in precision medicine. KEY MESSAGES: We have designed a microfluidic platform for CSC enriched culture by tumor sphere formation. Using MDs, we could quantify and determine sphere response after CT using murine and human cell lines as a proof of concept. MDs can be used as a tumor-derived sphere isolation platform to test the effect of antitumoral compounds in sphere proliferation.

GEMA-An Automatic Segmentation Method for Real-Time Analysis of Mammalian Cell Growth in Microfluidic Devices.

Nowadays, image analysis has a relevant role in most scientific and research areas. This process is used to extract and understand information from images to obtain a model, knowledge, and rules in the decision process. In the case of biological areas, images are acquired to describe the behavior of a biological agent in time such as cells using a mathematical and computational approach to generate a system with automatic control. In this paper, MCF7 cells are used to model their growth and death when they have been injected with a drug. These mammalian cells allow understanding of behavior, gene expression, and drug resistance to breast cancer. For this, an automatic segmentation method called GEMA is presented to analyze the apoptosis and confluence stages of culture by measuring the increase or decrease of the image area occupied by cells in microfluidic devices. In vitro, the biological experiments can be analyzed through a sequence of images taken at specific intervals of time. To automate the image segmentation, the proposed algorithm is based on a Gabor filter, a coefficient of variation (CV), and linear regression. This allows the processing of images in real time during the evolution of biological experiments. Moreover, GEMA has been compared with another three representative methods such as gold standard (manual segmentation), morphological gradient, and a semi-automatic algorithm using FIJI. The experiments show promising results, due to the proposed algorithm achieving an accuracy above 90% and a lower computation time because it requires on average 1 s to process each image. This makes it suitable for image-based real-time automatization of biological lab-on-a-chip experiments.

Metronomic doses and drug schematic combination response tested within chambered coverslips for the treatment of breast cancer cells (JIMT-1).

Low-dose metronomic (LDM) chemotherapy is an alternative to conventional chemotherapy and is the most frequently used approach in low dose chemotherapy regimens. The selection of patients, drug dosages, and dosing intervals in LDM is empirical. In this study, we systematically examined the schedule-dependent interaction of drugs on a breast cancer cell line (BCC) cultured in chambered coverslips. The LDM studies were combined with cell staining in order to better characterize different cell states and cell death modes, including caspase-dependent apoptosis, caspase-independent cell death and autophagy-dependent cell death. Microscope images were examined using the Fiji Trainable Weka Segmentation plugin to analyse cell area in 7500 images showing different modes of cell death. Paclitaxel combined with LDM chemotherapy demonstrated a reduction in the area covered by live cells. In contrast, there was an induction of high levels of cell death due to caspase-dependent apoptosis.

Color Engineering of Silicon Nitride Surfaces to Characterize the Polydopamine Refractive Index.

A simple methodology to generate polydopamine (PDA) surfaces featured with color due to thin-film interference phenomena is presented. It is based on depositing ultra-thin films of polydopamine on a Si/Si3 N4 wafer that exhibits an interferential reflectance maximum right at the visible/UV boundary (∼400 nm). Therefore, a small deposit of PDA modifies the optical path, in such manner that the wavelength of the maximum of reflectance red shifts. Because the human eye is very sensitive to any change of the light spectral distribution at the visible region, very small film thickness changes (∼30 nm) are enough to notably modify the perceived color. Consequently, a controlled deposit of PDA, tune the color along the whole visible spectrum. Additionally, good quality of PDA deposits allowed us to determine the refractive index of polydopamine by ellipsometry spectroscopy. This data can be crucial in confocal skin microscopic techniques, presently used in diagnosis of skin tumors.

Analysis of tumoral spheres growing in a multichamber microfluidic device.

Lab on a Chip (LOC) farming systems have emerged as a powerful tool for single cell studies combined with a non-adherent cell culture substrate and single cell capture chips for the study of single cell derived tumor spheres. Cancer is characterized by its cellular heterogeneity where only a small population of cancer stem cells (CSCs) are responsible for tumor metastases and recurrences. Thus, the in vitro strategy to the formation of a single cell-derived sphere is an attractive alternative to identify CSCs. In this study, we test the effectiveness of microdevices for analysis of heterogeneity within CSC populations and its interaction with different components of the extracellular matrix. CSC could be identify using specific markers related to its pluripotency and self-renewal characteristics such as the transcription factor Oct-4 or the surface protein CD44. The results confirm the usefulness of LOC as an effective method for quantification of CSC, through the formation of spheres under conditions of low adhesion or growing on components of the extracellular matrix. The device used is also a good alternative for evaluating the individual growth of each sphere and further identification of these CSC markers by immunofluorescence. In conclusion, LOC devices have not only the already known advantages, but they are also a promising tool since they use small amounts of reagents and are under specific culture parameters. LOC devices could be considered as a novel technology to be used as a complement or replacement of traditional studies on culture plates.