Micro and Nano Systems Letters最新文献

In recent decades, cancer has been dramatically leading to high amounts of death all over the world, and leukemia is one of the progressing cancers that should stop somehow. To prevent its health-threatening incidence, nanoparticle-based targeting drug delivery systems are crucially needed. As a result, the polyethylene glycol (P) modified and anti-CD19 antibody (Ab) decorated polyamidoamine (PAMAM G4: P) dendritic nano-complex was developed for effective delivery of sodium butyrate drug (D) to Reh6 leukemia cells in this research work. After the synthesis of the nano-complex, several analytical devices such as FT-IR, TGA, DLS, Zeta potential analyzer, and TEM were applied to the qualification and quantification of syntheses and conjugations. Nanometric size (less than 50 nm in diameter), −4.2 mV surface charge, high drug loading efficiency (14.42%), and appropriate controlled drug release (less than 50% within first 8 h at pH 7.4) profile at different pHs were observed for Ab-P-P-D nano-complex. In the biomedical phase, the MTT assay demonstrated 13.04% cell viability at 800 nM after 24 h of treatment. IC50 was obtained for 100 nM concentration. The Bcl2 and caspase9 genes were indicated less than half and more than 15 folds of expressions at post-treatment time, respectively. The cell cycle arrest was drastically depicted more than 15 folds of cell Reh6 suppression in comparison to control. Moreover, the leukemia cells treated with Ab-P-P-D have demonstrated 42.39% apoptosis which was potentially several folds more than control. These data have verified the potency of the nanocarrier as an effective drug delivery system.

Suspended microchannel resonator (SMR) has been demonstrated as a versatile technique, allowing to measure mechanical, morphological or even optical properties of cells. However, physical properties of cells may substantially change depending on the chemical composition of the suspension medium. Therefore, it is essential developing novel multiparametric techniques able to provide a complete understanding of the biological samples by characterizing also the liquid in which the cells are suspended. In this work we both theoretically and experimentally introduce a novel electro-mechanical sensing technique using SMR devices with integrated electrodes that allow measuring different physicochemical properties of the liquid sample as thermal conductivity, dielectric constant, electrical conductivity or even concentration of ions. These measured liquid properties can ultimately be used to complement other typical SMR measurements, such as mass. Moreover, we show that this electro-mechanical approach can be also used as a transduction method and as a way of tuning the mechanical resonance frequency.

Sign language is frequently used to facilitate communication between the normal and individuals having speaking and hearing difficulties. In this work, a triboelectric nanogenerator (TENG) based on smart gloves was designed for a self-powered sign language detection system. The TENG was fabricated using flexible materials like copper, aluminum electrodes, and polyethylene fabric (PE). To accommodate many finger positions and the backside of fingers as separate channels, the TENG was made to be both circular and rectangular in shape. Employing PE fabric as an active layer, these TENG devices can successfully harvest biomechanical energy from finger motions while being comfortable for the fingers. The TENG device with 4 cm × 4 cm dimensions demonstrated the highest voltage and current of 220 V and 750 nA, respectively, whereas the highest power of the device is 65 μW at 500 MΩ resistance. The TENG device was effectively used to charge various capacitors and power a low-power digital watch. The electrical outputs from performing the sign language gestures were collected using the TENG and translated into digital signals using Python. This sign-language detection based on the TENG system is completely tailorable, easy to fabricate, low-cost, and wearable. The emergency sign languages can be easily translated into text signals and can be recognized by non-signers, and take immediate action for the required scenarios.

The controlling and precise detection of nitrogen dioxide (NO₂) gas is important in many industrial processes such as medical, petrochemical, and agriculture. Therefore, this study investigates the gas sensing performance of zinc oxide (ZnO) nanosheets prepared using a hydrothermal approach. The morphology and structure of the as-prepared material were analyzed using analysis techniques, including transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The ZnO ink was spray printed in a square design onto an oxidized silicon wafer substrate, which includes a lithographically designed interdigitated pattern. ZnO nanosheets exhibited superior gas sensing performance, which is 5298% for sensor response and 96 and 600 s for response and recovery times, respectively, at 150 °C and 100 ppm of NO₂ gas. The previous results emphasize applying the proposed spray printing technique in different applications because of straightforward, versatile for different substrates, and cost-effective.

Graphical Abstract

Energy conversion mechanisms present in some harvesters are only able to provide very low voltage (mV) and frequency (few Hz) electrical signals, which may also have a bipolar nature (AC). These characteristics make unusable most conventional power converters to extract from them a DC voltage. This letter describes an autonomous self-starting ultra-low voltage and frequency AC-DC converter that can start the operation for AC signals around 25 mV, and below 10 Hz. The converter has been designed with ultra-low vibration harvesters in mind, but is also of application to, for instance, thermoelectric generators (TEG). The circuit is basically an oscillator driven by the harvester output, which therefore converts a low-frequency and low-voltage signal into large signal oscillation amenable for further DC conversion. The proposed circuit is based on the classical Hartley oscillator, which is modified in a nontrivial configuration, and optimized to be able to operate with bipolar, low frequency and voltage driving signals. This is achieved with a minimum number of passive components and a single JFET transistor. A practical prototype has been fabricated, and measurement results are obtained, demonstrating the feasibility of the approach. Moreover, a vibration harvester with the power converter proposed has been tested in real conditions in a wind turbine.

Heaters fabricated via printing conductive ink or paste on various flexible substrates have been extensively investigated. However, flexible/wearable heaters wherein all the functional structures (heater substrate, heating element, and cover layer) are fabricated via printing have not been reported. In this study, fully printed see-through conductors are fabricated using conductive Ag ink and dielectric ink and their potential for use as wearable see-through heaters is demonstrated. The relationship between the heater performance and the resistance of a printed Ag micromesh structure (which serves as the heating element) is analyzed. In addition, three types of printed heaters are fabricated based on different embedding configurations (three-sides open, one-side open, and fully embedded) of the Ag mesh electrodes, and their mechanical flexibilities are compared. The flexible heater based on the fully embedded Ag mesh structures exhibits remarkable mechanical flexibility. The rapid thermal response and high reliability of the printed flexible heaters are confirmed through Joule heating performance analysis. These results indicate the excellent potential of the proposed inkjet printing technology for the development of all-printed optoelectronics.

Nanoparticles (NPs) are redefining enzyme immobilization, offering a paradigm shift in biocatalysis through precision engineering at the nanoscale. With their exceptional surface area, tunable porosity, and customizable functionalities, NPs provide unprecedented control over enzyme stability, activity, and adaptability, bridging the gap between molecular-scale interactions and industrial-scale applications. In the era of intelligent bioprocessing, how can NP-based immobilization strategies be optimized to drive the next frontier of sustainable and high-performance enzyme technologies? A deep understanding of NP structural diversity, interfacial chemistry, and enzyme-matrix interactions is crucial to unlocking their full potential. This review systematically explores emerging NP-based immobilization platforms, including cross-linked enzyme aggregates (CLEAs), covalent organic frameworks (COFs), nanoflowers, nanofibers, carbon nanotubes (CNTs), graphene oxide (GO), ionic liquids (ILs), and layered double hydroxides (LDHs), each offering tailored advantages for catalytic enhancement and process efficiency. The review outlines current advancements such as 3D printing and wearable biosensors, forecasts the integration of artificial intelligence and smart nano-biocatalysts, and envisions futuristic applications including bio-intelligent nano/micro-robotic systems and space biosensors. Challenges, such as upscaling limitations, nanotoxicity concerns, and environmental risks, are addressed to ensure safe and viable implementation. This review provides a structured roadmap on (I) enzyme immobilization advances using next-generation NPs, (II) challenges in scalability and safety, (III) sustainability benefits of enzyme-based industrial biocatalysis, and (IV) the emergence of intelligence, adaptability, and nanoscale precision immobilization technologies and AI-assisted design and optimization. These visionary approaches mark a paradigm shift toward dynamic, adaptive, and highly specialized, multifunctional nano-enzyme systems.

Graphical Abstract

Skin diseases are among the most prevalent health issues worldwide, and the prevalence of these diseases is increasing, driven by factors such as aging populations and urbanization-related infrastructure imbalance. As skin diseases become more widespread, the need for their early detection and proper management is gaining prominence, underscoring the importance of developing advanced real-time skin health monitoring technologies. In this study, we propose a flexible, multi-layered skin health monitoring platform capable of the real-time measurement of key indicators such as humidity, sweat secretion, and pH levels. The platform collects sweat from direct skin contact, providing real-time, noninvasive data on humidity, sweat secretion, and pH levels, which are transmitted to a smartphone for continuous monitoring. Sensors for this platform were fabricated using inkjet printing, which enables low-cost and straightforward manufacturing, and were integrated into a vertically stacked configuration designed to fit wearable forms, such as eyewear. In addition, each sensor was constructed using a flexible substrate, making the platform adaptable to various applications beyond skin health monitoring. This platform holds potential for broader use across diverse areas of healthcare and medical science, laying the groundwork for technologies that enable continuous physiological monitoring to advance fundamental research and facilitate practical solutions.

Hydrogen sulfide (H₂S) is a colorless, flammable, and highly toxic gas that underscores the need for cost-effective, energy-efficient, simple, convenient, and durable detection methods. Resistive gas sensors based on inorganic conductive materials and organic conductive polymers can effectively address these requirements. This review discusses the hazards of H₂S gas and reviews sensors capable of detecting H₂S at room temperature, including those based on metal oxides, MXene/carbon materials, and p-type conductive polymers. It explores the mechanisms behind their enhanced response at room temperature, such as utilizing special structures (e.g., porous/hollow nanospheres, nanowires, nanotubes, and nanocapsules) to increase the effective surface area of the sensing materials, employing metal particles sensitization to improve gas adsorption, and leveraging heterojunctions to amplify the response. Additionally, this review highlights the limitations of these sensors and provides insights for the further development of low-power resistive H₂S gas sensors.

Omnidirectional wind energy harvesting has gained increasing attention as a means of harnessing the inherently variable and multidirectional flows encountered in real-world environments. Triboelectric nanogenerators (TENGs), which leverage contact electrification and electrostatic induction to convert mechanical motion into electrical power, are particularly well-suited for such applications due to their ability to operate effectively under low-speed and intermittent wind conditions. In this review, we first outline the fundamental triboelectric processes and operating modes that underpin TENG functionality, emphasizing how their low inertia and high-voltage outputs make them compatible with a wide range of wind profiles. We then discuss three predominant device classifications—rotary, aeroelastic, and rolling-based—highlighting their distinct mechanical configurations and capacities for omnidirectional capture. Key examples illustrate how strategically designed rotor geometries, flutter-driven films, and rolling elements can maximize contact–separation events and enhance triboelectric generation under complex airflow patterns. Finally, we examine the major obstacles faced by TENG-based harvesters, including durability, hybrid system design, and intelligent power management. Strategies to overcome these barriers involve wear-resistant materials, adaptive architectures, and advanced circuitry, offering TENG solutions that are feasible in micro- or off-grid scenarios.