Detection and monitoring of lactate and glucose levels in biological fluids and cell cultures are essential for understanding metabolic disorders. While electrochemical biosensors are commonly used, traditional enzymatic sensors face challenges related to stability, reproducibility, and cost. To address these limitations, we developed non-enzymatic sensors for lactate and glucose detection using nanostructured nickel oxide (NiO)–modified screen-printed carbon electrodes. The sensors were fabricated by drop-casting a NiO/Nafion/ethanol dispersion onto the working electrode, and their performance was evaluated using cyclic voltammetry and amperometry. Optimal sensitivity and linearity were achieved at a working potential of ∼0.5 V. The sensors exhibited linear responses for both lactate and glucose in the 0.1–5 mM range, with detection limits of 0.03 mM (lactate) and 0.025 mM (glucose), and sensitivities of 1.564 μA/mM (lactate) and 1.842 μA/mM (glucose) in 0.1 M NaOH–KCl electrolyte. To address glucose interference in lactate sensing, dual-sensing strategies were employed by varying Nafion concentration, applying differential potentials, or modifying the sensors with Prussian Blue to achieve selective detection. Validation against commercial lactate and glucose assay kits in cell culture medium showed good agreement, confirming the sensors’ accuracy. Finally, the sensor was integrated with a microfluidic chip, demonstrating its potential as a flow-through, enzyme-free metabolic sensor for future organ-on-a-chip applications.

Replicating the in vitro properties of tissue barriers—such as the blood-brain barrier, gut, skin, lung, kidney, retina, nasal epithelium, and placenta—is crucial for many applications, including drug screening, studying molecular transport, drug delivery, and disease modeling in preclinical studies. Organ-on-a-chip (OoC) platforms are advanced three-dimensional (3D) in vitro models that aim to replicate various aspects of organ functionality within microfluidic systems by providing microenvironments akin to native tissue. When used to model the interface between two different tissue compartments, OoC technology offers a promising platform for more accurately replicating the physiology and pathophysiology of various tissue barriers in the body. This review focuses on the state-of-the-art biomimetic tissue barrier models, ranging from two-channel tissue barrier-on-a-chip systems with a thin porous membrane to hydrogel-based membrane models. Specifically, it explores the engineering of tissue barrier-on-a-chip platforms, highlighting various fabrication techniques for microfluidic chips and membranes, as well as methods for functional characterization of the engineered tissue barriers. Additionally, we discuss the development of organ-specific barrier models and multi-organ-on-a-chip systems for studying inter-organ communication. Finally, we highlight the current challenges in the field and future directions in advancing tissue barrier modeling using OoC technology.

Neurons depend on glucose to sustain their high energetic demands; yet, ketone bodies can serve as alternative substrates during ketogenic states. Here, we examined how β-hydroxybutyrate reshapes metabolism and function in human iPSC-derived neurons. Neurons generated from neuroepithelial stem cells were cultured in glucose-rich media or low-glucose media supplemented with β-hydroxybutyrate. We developed an electrochemical biosensor for ketone detection and validated its performance by cyclic voltammetry and amperometry, achieving linear sensitivity in the 0.01 to 0.1 mM range. Metabolic changes for neurons were assessed through glucose consumption and lactate production, and transcriptional profiling revealed reduced expression of selected metabolic and ketone-associated genes under ketone supplementation. Calcium imaging further showed lower firing rates in ketone exposed neurons compared with glucose conditions. Together, these results demonstrate how alternative energy substrates modulate neuronal metabolism and excitability, providing a framework to evaluate metabolic interventions for neurological disorders.

Radiation-induced neurocognitive dysfunction after brain radiotherapy is a growing concern among the increasing numbers of long-term cancer survivors, particularly in children. This dysfunction significantly impacts memory, learning, and overall quality of life. Neural stem and progenitor cells (NSPCs) play a vital role in maintaining neurogenesis and plasticity, processes essential for memory formation and cognitive resilience. Currently, no effective treatments exist, highlighting the urgent need for strategies to mitigate these effects. One potential contributing factor to this dysfunction is the depletion or dysregulation of NSPCs following radiation. Here, we developed an in vitro microfluidic neurogenic niche setup to investigate how non-irradiated NSPCs respond to the inflammatory secretome produced by irradiated human fetal astrocytes (HFA) and human brain microvascular endothelial cells (HBMEC). NSPCs viability was dose-dependently affected when exposed to conditioned media from irradiated cells. Notably, NSPCs exposed to conditioned media from cells irradiated at 2 Gy and 8 Gy exhibited increased expression of SOX9 and S100B, respectively, suggesting a shift toward a gliogenic fate. Our findings suggest that this microfluidic model is valuable for exploring radiation-induced neurocognitive dysfunction and identifying potential therapeutic targets.

Solid-state nanopores in ultrathin (<20 nm) membranes enable label-free single-molecule sensing, but their adoption as sensors is limited by the lack of scalable manufacturing methods that deliver nanopores with single-nanometer reproducibility. Self-limiting metal-assisted chemical etching (MACE) in silicon-on-insulator (SOI) membranes offers a parallel wet-chemical route for nanopore fabrication, yet prior demonstrations lacked a predictive design rule and required electron microscopy or electrical tests for confirming presence and number of pores. Here, we convert self-limiting MACE into a manufacturing-oriented workflow with optical process control to obtain and verify the formation of 4 nm nanopores in a scalable fashion. We decouple the deposition of 200 +/- 10 nm gold (Au) nanoparticles from etching, enabling independent optimization of the two steps. The nanoparticle size allows for particle-per-membrane counting by dark-field optical microscopy, so that deposition can be repeated when counts are below target. We then map etching behavior across Au nanoparticle diameter d (10-200 nm) and silicon (Si) device-layer thickness t (5-18 nm), finding that d/t >= 0.8 ratio predicts self-limiting MACE behavior, where pore diameter becomes independent of particle size. In this regime, 200 +/- 10 nm catalysts yield 4 +/- 1 nm pores, corresponding to a reduction of similar to 50 & times; in pore diameter and similar to 10 & times; in pore-diameter variability compared to the catalyst diameter and related variability. Successful through-membrane pore formation produces undercuts in the buried oxide (typically similar to 200-300 nm diameter) beneath each pore, which can be characterized for each membrane by bright-field microscopy and used as a proxy for the otherwise optically invisible 4 nm pores. Together, the predictive d/t framework and two-stage optical verification establish a scalable wet-chemical route to fabricate nanopores for biomolecular sensing and related nanofluidic devices.

Nanopores in ultrathin membranes are central to single-molecule sensing, filtration, and energy conversion applications, yet fabrication of solid-state nanopores remains limited by fundamental trade-off between resolution, throughput, and tool complexity. Here, we report a scalable nanopore fabrication process that exploits stress-induced mechanical ripping to detach a fragment from a membrane with lateral dimensions in the nm-scale, forming pores with diameters down to the sub-10 nm regime, which is well below the resolution limit of the employed lithography. Using this approach, we demonstrate wafer-scale fabrication of nanopores at densities exceeding 105 pores per cm2 in dielectric (HfO2), semiconducting (SiGe), and metallic (Cr) membranes, including suspended HfO2 membranes as thin as 2 nm. We demonstrate the utility of the fabricated nanopores for high-performance surface enhanced Raman readouts of single molecule translocations. Beyond nanopore fabrication, this fracture-based approach points to broader opportunities for nanometer- and atomic-scale structuring of ultrathin materials.

Intraventricular hemorrhage (IVH) in preterm infants disrupts neurogenesis in the subventricular zone (SVZ), a key neurogenic niche, yet no effective treatments exist. This work develops a human SVZ-on-a-chip model to investigate the inflammatory response in IVH and its impact on neurogenesis. Using this platform, this work examines the effects of red blood cell lysate (RBCL) and hemorrhagic cerebrospinal fluid (CSF) from preterm infants with IVH on SVZ cells. Transcriptomic analysis reveal activation of inflammatory pathways in fetal astrocytes and brain microvascular endothelial cells exposed to hemoglobin isoforms. Notably, interleukin-1B (IL1B) is upregulated following RBCL and hemorrhagic CSF exposure. To probe its role, this work applies an IL1 receptor antagonist, which demonstrate that IL1B has a partially protective influence on neurogenesis. These findings highlight the SVZ-on-a-chip as a powerful tool for studying IVH pathology and emphasize the role of inflammation in regulating neurogenesis. IL1B emerges as a potential therapeutic target, offering new avenues for intervention. This study advances the understanding of IVH and lays the groundwork for developing strategies to protect the developing brain.

This protocol outlines the synthesis and use of engineered hyaluronan-based hydrogels for 3D cell culture and bioprinting of human induced pluripotent stem cell (hiPSC)-derived neuroepithelial stem cells (lt-NES). Key steps include hydrogel formation using bioorthogonal chemistries, cell encapsulation, and 3D bioprinting with a Cellink BioX printer, enabling the creation of complex tissue models. The protocol ensures high cell viability and supports differentiation, essential for neuroscience research and drug development.

Microphysiological systems (MPS) are advanced in vitro platforms engineered to replicate in vivo conditions for studying human biology, disease mechanisms, and drug responses with greater physiological relevance. Fluorescence sensing is widely used as a functional readout in MPS due to its high sensitivity, selectivity, and stability. However, conventional fluorescence sensing systems often rely on bulky instrumentation with limited integration, which restricts continuous in situ monitoring, scalable high-throughput analysis, and spatially resolved investigation in multi-organ-on-a-chip models. To address these limitations, we present a highly miniaturized, fully integrated optical system with a 1 mm² footprint, enabling continuous in situ fluorescence monitoring of three-dimensional microtissues in close proximity. The system integrates microscale illumination and sensing units for fluorescence excitation and selective detection, an optical element for guided light propagation, and a microcage for mechanical confinement of microtissues. To demonstrate its capabilities, we integrated the miniaturized optical system with an MPS-relevant platform to monitor fluorescence signals in transgenic mouse pancreatic islets expressing genetically encoded calcium indicators. The integrated platform enables real-time, continuous monitoring of islet responses to potassium chloride stimulation and tracking of calcium oscillations for over two hours, providing valuable information about the functional status of the pancreatic islets. Our work enhances the analytical capabilities of MPS through the integration of miniaturized on-chip quantitative assessment tools, enabling precise, in situ, and continuous monitoring of biological activities in close proximity.