Micro and Nano Systems Letters最新文献

Brain-on-a-chip is an emerging field involving microfluidic devices capable of mimicking the structure and function of the human brain. Existing research often focuses on single barriers, such as the blood–brain barrier or blood–cerebrospinal fluid barrier (BCSFB). However, the brain has both barriers working together, and mimicking this dual system is crucial for better understanding of brain (patho)physiology. In this work, we present a four-channel microfluidic chip model that incorporates both the BBB and BCSFB, to reproduce physiologically correct architecture. Using computer simulations, we demonstrate that this model can mimic both healthy and diseased states by adjusting the shear stress experienced by the barriers, which is a key factor in their function. These findings offer valuable insights for designing future brain-on-a-chip devices with improved accuracy. This improved technology could contribute to wider advancements in tissue engineering and the study of brain function and diseases.

Organoids are three-dimensional cell clusters derived from stem cells and closely resemble the physiological characteristics of human tissues. As the next-generation biological model, organoids provide new opportunities for drug discovery, disease modeling, and personalized medicine. To fully harness the potential of organoids, real-time monitoring of biological states and functional evaluation of organoids are crucial. This review highlights recent advances in real-time, in situ biosensing technologies, including microelectrode arrays for electrophysiological recordings, chemical sensors for biochemical detection, and strain sensors for monitoring mechanical properties. While the development of miniature sensors for non-invasive, long-term, and real-time monitoring of organoids is in the early stage, these sensors are an essential part of organoid technology which would provide new insights into human developmental biology, pathophysiology, and drug discovery. After reviewing the seminal works on the microfabricated sensors for organoids, we also provide an outlook of the field including a discussion on the remaining challenges and future directions with a focus on integration of multiple sensors to facilitate organoid research and applications.

In this paper, using high-dose implantation of O₂⁺ ions, nano-sized WO₃ films were obtained on the surface and at various depths of W(111) for the first time. It has been confirmed that when O₂⁺ ions are implanted into W at room temperature with low energy, partial formation of oxides such as WO, WO₂, WO₃ and WO₄ occurs. It has been proved that in order to obtain a homogeneous and good stoichiometry of W oxide, it is necessary to carry out oxidation at a certain temperature. The optimal modes for obtaining hidden oxide layers in the near-surface region of tungsten, the substrate temperature W, the energy and dose of O₂⁺ ions were determined. The concentration profiles of distributed O atoms in depth were studied for the three-layer W-WO₃-W(111) system. Using scanning electron microscopy, the formation depths and thicknesses of WO₃ layers were determined. The WO₃ films were polycrystalline. The resulting films have potential for creating thin-film OLED displays, as well as nanofilm MOS transistors.

Digital microfluidic systems, based on the electrowetting-on-dielectric mechanism, allow the manipulation, dispensing, merging, splitting, and mixing of micro- to nanoliter droplets on hydrophobic surfaces by applying voltages to an array of planar electrodes. The manipulation of both a non-aqueous and an aqueous phase droplet in a single experiment has gained considerable interest. This study focuses on characterizing the dispensing and dosing of 1-octanol droplets, merging with a water droplet, and phase separation with minimal residue formation by shearing off the biphasic droplet at a tear-off edge of a hydrophilic well, using optimized actuation parameters. The volume of the 1-octanol droplet dispensed from an L-junction reservoir design increased with increasing dispensing speed. Dispensing can only occur within a certain reservoir volume range. Under identical conditions, 1-octanol droplets could be dispensed with volume variations of less than 0.55%, and manipulated at a maximum velocity of 5.6 mm/s when the frequency of the applied AC voltage was about 200 Hz. At the tear-off edge of the hydrophilic well, the 1-octanol residue on the water droplet was reduced to less than 0.15% of the original 1-octanol droplet volume. The results will be used for future applications, such as for the precise quantitative characterization of the reaction kinetics of complex parallel or sequential interfacial catalytic reactions, for the study of self-assembly processes or for liquid–liquid extractions at the 1-octanol–water interface.

This work evaluates the use of zinc oxide nanorods as intensifiers of a latent heat thermal energy storage system working with adipic acid as the phase change material (PCM). By virtue of not participating directly in the solid–liquid and liquid–solid phase transition, ZnO-adipic acid composites (ZnO-adipic acid) possessed lower specific heat and latent heat. Our results have shown that the overall heat transfer coefficient during the freezing of PCM through heat transfer to a well-mixed liquid bath is amplified by 61%, when adipic acid is replaced with 2 wt.% ZnO-adipic acid. Heterogenous nucleation due to well-dispersed, ZnO nanorods caused this enhancement. The large enhancement in discharge rate of 2 wt.% ZnO-adipic acid during freezing overweighs higher degree of latent heat loss due to its repeated thermal cycling. The enhancement in overall heat transfer coefficient reported here (61%) is the highest reported so far for any latent heat thermal energy system employing adipic acid or its composites.

The present study explores the application of X-ray scattering, using synchrotron radiation, to assess the diffusive transport of nanomedicines in tumor on a chip devices fabricated by 3D stereolithography using a resin with high optical and X-ray transmittance. Unlike conventional methods that require fluorescent labeling of nanoparticles, potentially altering their in vitro and in vivo behavior, this approach enables the investigation of the transport properties for unlabeled nanoparticles. In particular, the results presented confirm the influence of the porosity of the extracellular matrix-like microenvironment, specifically Matrigel, on the diffusive transport of oligonucleotide-functionalized gold nanoparticles. The analysis of the scattering patterns allows to create 2D maps showing the nanoparticle distribution with high spatial resolution. The proposed approach demonstrates the potential for studying other factors involved in nanoparticle diffusion processes. By implementing X-ray scattering to track unmodified nanomedicines within extracellular matrix-like microenvironments, increasingly accurate models for evaluating and predicting therapeutics transport behaviors can be developed.

Simultaneous detection of multiple neurotransmitters and their related activities is crucial for enhancing our understanding of complex neurological mechanisms and disorders. In this study, we developed a flexible, high-sensitivity multi-electrodes array probe capable of concurrent detection of four neurotransmitters: dopamine, serotonin, acetylcholine and glutamate. The probe was fabricated on a polyimide substrate with 16 circular gold-film electrodes. These electrodes were modified with PEDOT/GluOx and PEDOT/ChOx for enzymatic detection of glutamate and acetylcholine, and with rGO/PEDOT/Nafion for the detection of dopamine and serotonin. Our electrochemical sensor achieved sensitivities of 184.21 and 219.29 μA/μM cm² for glutamate and acetylcholine, respectively, with limits of detection (LOD) of 0.0242 and 0.0351 μM within a concentration range of 0.1–100 μM. For dopamine and serotonin, the sensor showed sensitivities of 195.9 and 181.2 μA/μM cm², respectively, with LOD of 0.4743 and 0.3568 μM. This research advances the field of neurochemical sensing and provides valuable insights into the balance of neurotransmitters associated with neurological disorders. These insights improve diagnostic and therapeutic strategies.

One of the physical methods for obtaining magnetite nanoparticles (NPs) is electron beam physical vapor deposition (EB PVD), which requires complex equipment, but allows obtaining a significant amount of pure (ligand-free) NPs. The biomedical application of such NPs is less studied than materials from other synthesis methods. The objective is to study the effect of pure magnetite NPs in the NaCl matrix obtained by EB PVD on hematological indicators, gases, electrolytes and parameters of iron metabolism in the blood of intact animals. The physical characteristics of NPs were studied using high-resolution transmission electron microscopy, scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping, electron energy-loss spectroscopy, selected area electron diffraction and fast Fourier transform. In vivo experiments were conducted on albino male rats, which were injected with solution of magnetite-sodium chloride NPs (1.35 mg Fe/kg). After 3 and 72 h, hematological parameters, blood gases, electrolytes, and serum iron were determined. The synthesized NPs had an average size of 11 nm. They were identified as magnetite, where polycrystals and single crystals were present. The absence of contamination in crystal boundaries, clear orientation and orderliness of atoms in crystals were established. The administration of NPs in the sodium chloride matrix to animals was characterized by a transient increase in the main indicators of red blood accompanied by an increase in the saturation of erythrocytes with hemoglobin and their mean volume after 3 h. It did not worsen blood gases and pH, but decreased blood Na⁺ content after 72 h. The investigated NPs caused changes in the parameters of serum iron characteristic to iron preparations, which after 3 h were smaller compared to the reference iron drug, and after 72 h—similar to it. More intense rapid effects on hematological parameters at lower serum iron indicate greater activity of the studied pure magnetite NPs obtained by EB PVD syntesis compared to the reference iron preparation.

The synthesis of a co-precipitated mixture of tantalum and brass nanoparticles (Ta and Cu/Zn) using a micro-wire-electro-discharge-grinding (µ-WEDG) with a combination of multiple process parameters is explained in this article. Tantalum and brass nanoparticles are produced in a dielectric medium Diel-7500 EDM oil. µ-WEDG represents a cutting-edge mechanical micro-machining technique extensively employed for machining micro rods. This method uses a grinding process that expels debris via melting and evaporation. This process disperses a fraction of nanometre-sized debris within the dielectric medium. Traditionally, this debris consisting of nanoparticles has been classified as unwanted substances and subsequently eliminated from the system. However, it now requires a thorough reassessment for possible usage. Hence, the characterization of tantalum and brass nanoparticles is conducted through Field emission Scanning Electron Microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analyses. The process parameters are capacitance, voltage and spindle speed. The investigation reveals that the mean nanoparticle size of produced tantalum nanoparticles range from 25 to 200 nm, while brass nanoparticles range from 300 to 950 nm. Furthermore, a notable correlation is observed between decreasing capacitance and the corresponding reduction in the shape and size of nanoparticles.

The purpose of this paper is to identify the relationship between human augmentation and personal combat ability improvement that overcomes physical and mental limitations according to the convergence of advanced science and technology such as biotechnology, brain engineering, and mems-based technology. We will first explain the background of the emergence of human augmentation and derive the characteristics of human enhancement through conceptual analysis of the correlation of human augmentation and cognitive abilities, which hold importance for future warfare. Afterward, through the development of brain engineering, we will present areas where advanced science and technology can contribute to improving military combat capabilities, such as cognitive abilities, decision-making abilities, situation recognition abilities, and brain stimulation. Finally, we will review the MEMS-based neural interface systems for the enhancement of human augmentation and individual combat ability.