BioChip Journal最新文献

Researchers have placed engineered or natural tissues within microfluidic chips originating the so-called organ-on-a-chip (OoC) devices. With this technology, organ models can be subjected to phenomena that replicate the complex in vivo biological environment. Furthermore, the OoC devices constitute a more valuable, cost-effective and ethical option when compared to assays performed in animal models for disease research and drug discovery. However, there are still many challenges in replicating some organs/diseases in vitro such as the Blood–Brain Barrier (BBB), given its complexity and structure. Despite the difficulties, many efforts have been made to develop improved in vitro BBB-on-a-chip models to investigate several neurological disorders. In the present review, a summary of the progress made in the development of BBB-on-a-chip is provided focusing on the importance of using numerical simulations for obtaining improved models and better planning the experimental assays. In addition, the future perspectives and current challenges are provided.

In the evolving landscape of cancer research, 3D cell cultures, particularly tumor cell spheroids, are increasingly preferred in drug screening due to their enhanced mimicry of in vivo tumor environments, especially in drug resistance aspects. However, the consistent formation of uniform spheroids and their precise manipulation remain complex challenges. Among various methodologies, droplet microfluidics emerges as a highly effective approach for tumor spheroid formation. This paper introduces a novel, multifaceted microfluidic system that streamlines the entire spheroid cultivation process: (i) generating tumor spheroids from cell suspensions within individual droplets, (ii) merging these droplets into a continuous aqueous phase once spheroid formation is complete, and (iii) transferring the spheroids to a specialized cultivation area within the chip, equipped with trapping elements for extended cultivation in perfusion mode. Remarkably, this process requires no hydrogel encapsulation or external handling, as all operations are conducted within the microfluidic chip. Fabricated from the innovative OSTE+ (off-stoichiometry thiol-ene epoxy) polymer, the chip is designed for repeated use. To show its efficacy, we successfully formed spheroids from MCF-7, GAMG, and U87 cell lines in our system and compared them with spheroids prepared by a traditional agarose microwell method. Additionally, our methodology has successfully enabled the in-chip release of spheroids from droplets, followed by their effective trapping for subsequent cultivation, a process we have exemplified with MCF-7 spheroids. To our knowledge, this research represents the first instance of a fully integrated droplet microfluidic platform achieving scaffoldless tumor spheroid formation and handling. Our method holds promise for improving high-throughput, automated procedures in the formation, transfer, and cultivation of tumor cell spheroids.

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Nanofluidic phenomena, particularly Ion Concentration Polarization (ICP), have been actively utilized for advancing various research fields, including chemical analysis and biomedical diagnostics, over the past century. While ICP can be used as effective preconcentration techniques in bio-/chemical analysis, there are few studies to investigate the shape of preconcentration plug, especially perpendicular distribution of analyte in the preconcentration plug. Previously we have reported the theoretical analysis of the distribution so that the types of plug were categorized as dumbbell or plug shape. In this study, we further investigated the classification of real DNAs within micro-/nanofluidic devices by examining the preconcentration dynamics of different DNA types under diverse electrical conditions. Our investigation successfully distinguished distinct preconcentration profiles for Short DNA, Multi-short DNAs, and Equitable DNA with introducing the concept of the Radius of Gyration for Fluorescence (RGF). We provided a quantitative framework to analyze and differentiate preconcentration shapes with reasonable precision. These findings not only deepen our understanding of DNA preconcentration dynamics but also provide implications for genetic diagnostics. As a simpler and more accessible pre-test tool, our research could be utilized as the efficient genetic testing, particularly in diagnosing disorders characterized by variations in DNA length.

Cisplatin, which is commonly used in tumor treatment, and gentamicin, which is widely used as an antibiotic, both induce nephrotoxicity as a side effect. In this study, a nephrotoxicity model for these two drugs was constructed using the organ-on-a-chip technology, which is an alternative to animal tests. Using injection-molded polycarbonate chips, human renal proximal tubular epithelial cells (HRPTECs) and human umbilical vein endothelial cells (HUVECs) were co-cultured to mimic the apical and basolateral sides. To induce nephrotoxicity, cisplatin and gentamicin were administered, and cell viability and toxicity markers were confirmed via cell viability, live/dead staining, and confocal fluorescence microscopy imaging of the samples. In addition, renal tubule function was quantitatively evaluated through transepithelial electrical resistance, glucose reabsorption, and permeability analyses, and the concentrations of the nephrotoxic biomarkers kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin were measured using enzyme-linked immunosorbent assay. An organ-on-a-chip model mimicking the apical and basolateral sides co-cultured with HRPTECs and HUVECs was developed, which served as a nephrotoxicity model with impaired renal function. This model is expected to resolve interspecies discrepancies in nephrotoxicity during drug development and significantly reduce the time and cost involved in preclinical and clinical trials.

The enzyme-linked immunosorbent assay (ELISA) is the most widely used technique for the selective detection of various analytes due to its advantages of sensitivity, simplicity, versatility, and high throughput. However, conventional ELISA is not sufficient to detect biomarkers at lower concentration ranges, such as low pM levels. Therefore, we developed multi-horseradish peroxidase (HRP)-conjugated branched polyethyleneimine (PEI)/antibody-functionalized gold nanoparticles (mHRP/bPEI/AuNPs) that immobilize a large number of HRP enzymes to lower the threshold for target antigen detection. Briefly, mHRP/bPEI/AuNPs were fabricated by attaching branched PEI with many enzyme molecules to the surface of streptavidin-HRP-coated AuNPs. The fabricated mHRP/bPEI/AuNPs were applied as a detection probe in ELISA, enabling the quantitative detection of the breast cancer biomarker Thioredoxin-1 (Trx-1) in a range from 10 pM to 100 nM and showed 10³ times greater sensitivity than conventional ELISA, with a limit of detection (LOD) of 1.7 pM for Trx-1. These results suggest that the higher number of enzymes present in mHRP/bPEI/AuNPs amplifies the signal and increases the detection sensitivity. Consequently, we expect that mHRP/bPEI/AuNPs can be used in situations requiring the detection of low concentrations of biomarkers, such as early disease diagnosis.

The concern regarding tetrodotoxin (TTX), a highly hazardous marine neurotoxin found in puffer fish, has expanded beyond Asia due to the migration of puffer fish caused by the rise in global temperatures. This highlights the urgent need to develop fast yet reliable methods for detecting TTX. In this study, we developed a peptide-based potentiometric TTX sensor based on a polypyrrole/Au nanoparticle-modified carbon screen-printed electrode (PPy/AuNP SPE). The bioreceptor responsible for recognizing TTX is a specific binding peptide that was discovered through phage display technique. The phage-displayed peptide candidates were sorted based on frequency and similarity, and their binding affinity was subsequently assessed via phage enzyme-linked immunosorbent assay. The C-terminal of the specific binding peptide was then modified with cysteamine to facilitate its immobilization through Au–S bonding on the PPy/AuNP SPE platform, thereby constructing the TTX sensor. The sensing platform was prepared by successive electrodeposition of polypyrrole and AuNP onto the surface of carbon SPE as a substrate. Both materials play significant roles to improve the poor conductivity of carbon SPE and provide sufficient immobilization sites for TTX receptors, respectively. Finally, the PPy/AuNP TTX sensor demonstrated a detection limit of around 2.80 ppb with a detection range from 2 to 1000 ppb, making it a promising platform for rapid and reliable marine toxin detection.

In this study, La_0.25Fe_0.75FeO₃ (PNp)perovskite nanoparticle was synthesized using the sol–gel method. PNp-coated polyacrylonitrile (PAN) nanofibers were prepared by electrospinning on the pencil graphite electrode (PGE) surface. In another step, carcinoembryonic antigen (CEA) was loaded with CEA antibodies (Anti-CEA) as a biomarker receptor. Finally, PGE/PAN@PNp/Anti-CEA was used for CEA detection. Optimization steps and cell culture steps were performed using differential pulse voltammetry (DPV). The use of this composite system is a novel immunosensor development approach for label-free detection of CEA. Under optimum conditions, detection limit (LOD) of PGE/PAN@PNp/Anti-CEA immunosensor LOD 1.48 ng/mL, limit of quantification (LOQ) = 4.94 ng/mL, reproducibility 1.46% (n = 5) and R² = 0.9984 for antigen concentration within a linear working range of 0.1–10 ng/mL. Also, immunosensor recovery in real serum samples containing dopamine and ascorbic acid was found as 98.94 ± 7.43. It has great potential in clinical screening of different cancer biomarkers. The number of cells attached to the PGE/PAN@PNp/Anti-CEA/BSA(bovine serum)/CEA surface decreased in RT-4(bladder cancer), MDA-MB-231 (triple-negative breast adenocarcinoma cell line), and T98G cells (glioblastoma multiforme cell line), which are known as CEA-negative cell lines, whereas the number of MCF-7 cells (estrogen-sensitive human breast cancer cell line, known to be CEA positive) attached to the PGE/PAN@PNp/Anti-CEA/BSA/CEA surface increased, indicating higher affinity to the immunosensor surface. As a result, while MCF-7, which is CEA positive, can be determined best when using an immune-cytosensor, the cell that can be best determined with cytosensors was found to be RT-4.

Diffusion layer dispersed electrodes were presented for application in electrochemical immunoassays. The diffusion layer refers to the region on the electrode surface where concentration gradients occur during the redox reactions of the target analytes. To control the diffusion layer, electrodes of the same area and size were fabricated, and the shape of the diffusion layer was controlled by adjusting each electrode distance. To estimate the properties of the electrodes, cyclic voltammetry (CV) analysis was performed using ferricyanide ([Fe(CN)₆^–3]) and 3,3′5,5′-tetramethylbenzidine (TMB) as a model redox couple. Changes in the diffusion layer shape according to electrode distance were compared through simulation. The redox currents for the target analytes increased as electrode distance increased. These results indicate that even if the electrode shape and area are the same, dispersing the diffusion layer by adjusting the distance between the electrodes can affect the microelectrode characteristics. Finally, the diffusion layer dispersed electrode was applied for the medical diagnosis of the human hepatitis B virus (hHBV) antigen, and the human hepatitis C virus (hHCV) antibody was compared with conventional assay methods, such as TMB-based chromogenic detection.

Overlimiting current (OLC) is a non-linear current response that occurs related to an ion concentration polarization (ICP) phenomenon in micro/nanofluidic systems and holds great importance since it represents the rate of selective ion transportation through perm-selective structure. For last two decades, numerous studies of OLC have been reported about understanding the fundamentals of nanoelectrokinetics and enhancing ion transportation through perm-selective membranes. Recent study reported that the alignment of non-uniform microspace near the perm-selective membranes in two-dimensional micro/nanofluidic systems can significantly enhance OLC, i.e., overlimiting conductance (σ_OLC). This is attributed to recirculation flow induced by combination of unbalanced electroosmosis and induced pressure driven flow among non-uniform microspaces. However, 2D micro/nanofluidic systems have limited practicality due to their small volume and low throughput. Herein, we tested the OLC enhancement using 3D-printed hierarchical micro/nanofluidic systems with respect to the non-uniformity of microspaces. The 3D microspaces were fabricated as a mesh structure using a conventional 3D printer. By comparing current–voltage measurement with each type of mesh, we experimentally confirmed the generation of recirculation flow among non-uniform meshes and ionic current enhancement in 3D hierarchical micro/nanofluidic system. Also, we further investigated the enhancement of overlimiting conductance depending on the mesh pattern. Furthermore, we validated that this effect of microscale non-uniform compartmentalization, both increasing surface area and aligning non-uniform spaces, appears not only at low molar concentration but at high molar concentrations. This demonstration can offer a strategy to design optimal electrochemical systems where a perm-selective ion transportation is crucial.

This review paper aims to critically assess the advancements, challenges, and future prospects of kidney-on-chip (KOC) technology in studying antibiotic-induced kidney injury. Despite significant progress, challenges such as limited throughput and the need for more accurate physiological replication persist. By analyzing current literature and technological developments, this review identifies key issues and outlines future directions for KOC research. Through an exploration of sensor integration, high-throughput screening capabilities, and automation, this review seeks to address these challenges and propel KOC toward more efficient and predictive drug-testing methodologies.