Discover nano最新文献

Electromagnetic pollution has intensified with the rapid expansion of wireless technologies and compact electronics. This has created a high demand for lightweight materials that can absorb microwaves (MA) and shield against electromagnetic interference (EMI). Foam-based structures are promising options because their porous designs naturally match impedance, promote internal reflections, and enable various loss mechanisms. These structures are also very light. Recent fabrication methods, such as freeze casting, space-holder replication, 3D printing, sol-gel foaming, and bio-templating, allow precise control over pore size, anisotropy, and the formation of conductive or magnetic networks. This enables customization of shielding performance. This review offers an integrated assessment of various foams, including metal, carbon, polymer, composite, and hybrid types. It examines how pore shape, interfacial properties, and filler connectivity influence conduction loss, interfacial polarization, magnetic interactions, and absorption-based attenuation. A major contribution is the systematic comparison of specific shielding effectiveness-measured as SE per density and SE per density-times-thickness-across representative systems. These comparisons show that optimized foam structures can outperform dense materials on a weight basis. This advantage is especially important for aerospace, wearable electronics, and portable devices. The review also highlights persisting challenges, including limited structure-property models, thermochemical instability, and measurement artefacts in ultralight foams. Finally, it outlines three promising research paths; biodegradable foams, magnetically tunable hybrids, and impedance-graded architectures, positioning foam-based materials as strong candidates for next-generation, sustainable EMI shielding.

Polyelectrolyte capsules (PEC) are hollow polymer particles fabricated by layer-by-layer (LbL) assembly of subsequently deposited polyelectrolytes of alternating charge. PECs, valued for their tunability and cargo encapsulation capabilities, are interesting for biomedical applications, underscoring the need for standardized fabrication and characterization techniques to optimize it for specific biomedical tasks. Here common protocols on how to synthesize and characterize such capsules are summarized. The fabrication of both, biodegradable and non-biodegradable capsules ranging in size from 800 nm to 5 μm is outlined. The entire preparation process-from the synthesis of sacrificial templates with diverse sizes and morphologies, to the controlled LbL deposition of polyelectrolyte shells and subsequent core dissolution is detailed. Here, calcium carbonate is selected as the sacrificial template of focus, owing to its high biocompatibility and loading capacity. Particular emphasis is placed on strategies for cargo loading, including co-precipitation and post-loading methods. Furthermore, the key characterization methods essential for confirming PEC formation-including size and zeta potential measurements (via dynamic light scattering), capsule concentration analysis (using optical or fluorescence microscopy), cargo encapsulation quantification (by UV-Vis spectroscopy or fluorescence analysis), and structural analysis (using transmission electron microscopy, TEM)-are highlighted and discussed. Finally, the review addresses current advantages and limitations in PEC fabrication, such as scalability and uniformity, and proposes future directions involving microfluidics, automation, and template design for the next generation of advanced biomedical applications.

Electrospinning has emerged as a powerful nanofabrication technique for producing continuous polymer nanofibers with diameters ranging from sub-micrometers to nanometers. This technique is important in several discipline areas which are able to make high-surface-area materials with tunable properties that will allow applications for biomedicine, filtration, and tissue engineering. This review explores both needle-based and needleless electrospinning methods, including their sub-techniques, advantages, limitations, and influencing process parameters. Particular attention is given to how electric field strength, solution properties, and environmental factors affect nanofiber morphology and performance. In parallel, the review delves into the physicochemical characteristics and structural dynamics of starch, a biodegradable and renewable polysaccharide with vast potential in nanotechnology and food science. The phenomena of starch gelatinization and retrogradation are examined with respect to their functional implications in fiber formation and food applications. By integrating insights from electrospinning and starch science, this study highlights the prospects for developing starch-based nanofibers, offering sustainable solutions for biomedical, packaging, and dietary applications. This paper, in contrast to the most recent reviews describing electrospinning principles or the properties of starch independently, does provide a meaningful comparison of needle-based versus needleless techniques, and evaluate the effects of starch's physicochemical transitions on nanofiber performance. This comparative analysis can identify existing gaps, and show where starch-based systems were stronger than synthetic polymers with regards to sustainability, but weaker in mechanical strength and scalability. The paper concludes with future research directions that bridge nanotechnology and biopolymer engineering.

Viral infections during pregnancy can lead to several adverse outcomes, including miscarriage, stillbirth, intrauterine growth restriction, and neonatal complications, which may manifest congenital malformations and organ dysfunction. Infants who exhibit symptoms following maternal infection tend to have poorer health outcomes compared to their asymptomatic counterparts. Various viruses are known to cause birth defects, with the most common being cytomegalovirus (CMV), rubella virus, hepatitis B and C viruses, herpes simplex viruses 1 and 2, human herpesvirus 6 (HHV-6), Zika virus, and human immunodeficiency virus. In this review article, we examined the most prevalent maternal viral infections that can cross the placental barrier and affect the fetus, potentially resulting in severe damage. Nanomedicine emerges as a promising candidate capable of traversing the placenta to mitigate viral infections in the fetus, thereby minimizing damage. We explored several classes of nanoparticle-based clinical approaches, along with their associated complications and success rates in various trials targeting different types of maternal viral infections. Additionally, we discussed several nanomedicines that can effectively combat viral infections during pregnancy, serving as potential safeguards for both the mother and the fetus.

The current-voltage behavior of three DNA nanowire models, which consist of a fishbone structure and two separate double-chain setups, alongside an RNA model illustrated by a half-ladder configuration, is examined using zigzag carbon nanotubes and associated metallic armchair graphene nanoribbon electrodes. This study utilizes the tight-binding Hamiltonian technique within the Landauer-Büttiker theory. The different DNA and RNA nanowire models exhibit nonlinear current-voltage characteristics, which are calculated and analyzed based on the corresponding transmission probability. The findings show that the current-voltage properties are affected by the type of leads and their working temperature, with zigzag nanotubes producing somewhat greater currents than nanoribbon electrodes. With a near-zero bias at the electrodes, the current-voltage characteristics are influenced by the dimerization effects of longitudinal hopping in the devices. Due to the expected strong connection between electronic transport characteristics and the structures of DNA and RNA, these results might stimulate additional investigation into their biological importance for nanoelectronic devices.

In this research, aluminum/cobalt oxy-hydroxide (CoAl) thin films were successfully deposited using the layer-by-layer (LbL) method at RT. CoAl nanocomposites were grown on a stainless-steel substrate for 10, 20, and 30 LbL cycles. The structural analysis of CoAl was performed using X-ray diffraction and Fourier transform infrared spectroscopy analyses. The FESEM analysis revealed a three-dimensional flower-like porous nanostructure of the composite. A three-electrode system was employed for electrochemical testing, with the produced AlOOH/CoO(OH) binary composite acting as the working electrode. The electrochemical characteristics of the CoAl samples were analysed in a 1 M KOH aqueous electrolyte. Among 10, 20, and 30 LbL cycles, the 20 LbL cycles nanocomposite exhibited the outstanding specific capacity of 2421 C g^-1@ 5 mV s^-1 within a potential range of 1.4 V. The nanocomposite exhibits pseudocapacitive battery-type behaviour. The remarkable electrochemical activity of the 20 LbL nanocomposite can be ascribed to the lower resistances identified in the sample through EIS analysis and the high surface area of the interconnected nanosheets that form a porous, nano flower-like structure. The combination of AlOOH with CoO(OH) contributes to an improvement in its charge storage capability.

CRISPR/Cas9-mediated programmable gene editing has disrupted the biotechnology industry since it was first described in 2012. Safe in vivo delivery is a key bottleneck for its therapeutic use. Viral vector-mediated delivery raises concerns due to immunogenicity, long-term expression, and genomic disruption. Delivery of pre-complexed ribonucleoprotein (RNP) reduces off-target effects, and recombinant Cas9 production is more cost-effective than viral vector synthesis. CRISPR-Cas RNPs do not possess intrinsic cell entry mechanisms, and physical delivery methods are confined to ex vivo editing, necessitating non-viral delivery approaches. Nanogels (NG) are biocompatible polymeric nanoparticles capable of entrapping proteins. Here, we report the first proof of principle that NGs from thiol-functionalized polyglycidol can entrap active RNPs with high efficiency (60 ± 2%). We call these particles CRISPR-Gels. A commercially available E. coli lysate for cell-free transcription and translation (TXTL) was used to mimic the intracellular reductive degradation of NGs while providing a real-time fluorescence readout of RNP activity. Degradation and RNP activity were observed within 30-90 min. The described TXTL assay can be utilized to evaluate the release of RNP in a cytosol-mimicking environment from redox-sensitive nanoparticles in a high-throughput and cost-effective way. Further studies are needed to assess the in vitro and in vivo performance of CRISPR-Gels.

Currently, there is unprecedented emergence of antimicrobial resistant (AMR) bacteria which demand urgent development of novel strategies to combat bacterial infections in humans. In this study, we report on a facile and eco-friendly green synthesis of silver-silver chloride nanoparticles (Ag/AgCl-NPs) using macadamia (Macadamia integrifolia) nutshell (MNS) agro-waste. The effects of physicochemical parameters including pH, Ag ion precursor concentration, time, and temperature were investigated. The biosynthesized Ag/AgCl-NPs sample was characterized using ultraviolet visible spectroscopy (UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) spectroscopy, field emission scanning spectroscopy (FE-SEM), Transmission electron microscopy (TEM), and energy dispersive X-ray (EDX). UV-Vis spectroscopy exhibited surface plasmon resonance (SPR) between 420 and 446 nm typical for silver nanoparticles (AgNPs). FT-IR spectroscopy provided an insight of the phytochemicals responsible for the reduction of Ag⁺ into Ag^o and capping/stabilizing the formed Ag/AgCl-NPs. XRD spectroscopy revealed the formation of crystalline Ag/AgCl-NPs with characteristic peaks at around 38.3°, 44.1°, 64.6°, and 77.5° for AgNPs, and 28.9°, 31.9°, 45.4°, 56.3°, and 66.1° for AgCl NPs. FE-SEM spectroscopy exhibited spherical and block like morphologies of agglomerated Ag/AgCl-NPs. TEM illustrated polydisperse spherical shapes of Ag/AgCl-NPs with average particle sizes of 31.11 nm. EDX confirmed the presence of Ag and Cl elements confirming the formation of Ag/AgCl-NPs. The antibacterial activity of the green synthesized Ag/AgCl-NPs was performed using disc diffusion method and the zone inhibition (ZOI) evaluation showed their effectiveness against Gram negative (E. coli) and Gram positive (S. aureus).

Transformative bioprinting, particularly 4D printing, is revolutionizing the field of biofabrication, offering dynamic solutions that respond to external stimuli. This paper explores the underlying mechanisms, materials, and stimuli that enable 4D printing to fabricate responsive and adaptive constructs. Section 1 delves into the foundational aspects of 4D bioprinting, detailing the stimuli-responsive materials, such as hydrogels and shape-memory polymers, and the mechanisms that drive their transformation. Additionally, the role of external factors, including temperature, pH, and magnetic or light-based stimuli, is analyzed to provide a comprehensive understanding of this evolving technology. Section 2 focuses on the diverse applications of 4D bioprinting, particularly in biomedical sciences. Key use cases include tissue engineering, drug delivery systems, and the creation of adaptive implants. Beyond healthcare, the potential for smart structures in fields like robotics and aerospace is highlighted, showcasing the technology's ability to deliver tailored, dynamic solutions across various domains. Section 3 categorizes additive manufacturing techniques relevant to 4D printing, offering an in-depth classification and comparison. This includes extrusion-based, vat polymerization, and inkjet printing technologies, emphasizing their compatibility with stimuli-responsive materials. Section 4 shifts focus to commercial advancements, presenting a classification of 4D bioprinters available in the market. The economic barriers, challenges in scalability, and ease of application for these printers are critically examined. Proposed solutions, such as innovative material sourcing, streamlined design strategies, and integration with AI for optimized performance, are presented to address these issues. This work provides a roadmap for integrating 4D bioprinting into scalable and cost-effective production, pushing the boundaries of biofabrication. It serves as a comprehensive guide for researchers and industries aiming to harness the transformative potential of 4D printing for adaptive and functional applications across various domains.