ACS Applied Nano Materials最新文献

In this study, hybrid coating systems comprising biopolymers (chitosan, N-succinyl chitosan, or sodium alginate, and sodium carboxymethylcellulose) and iron oxide nanoparticles (IONPs) were synthesized, and their antiviral activity against the coronavirus as well as their dermal toxicity in rats were evaluated. The hybrid systems were applied as coating surfaces with virucidal properties against the coronavirus. IONPs were synthesized by using the coprecipitation method, with TEM images revealing their crystalline structure and an average size of 5.6 nm. XRD analysis confirmed the predominance of magnetite in the nanoparticles. Zeta potential analysis assessed the suspension stability of the biopolymer-based antiviral solutions at different IONP concentrations (1.4, 2.8, and 4.1 mM). The hybrid systems were designed for coating cotton fabric, and SEM, EDS, and FTIR characterized the coated surfaces. Among the coatings, the N-succinyl chitosan-based (IONPs/NSC) coating showed the lowest iron ion release after 24 h compared to other polymers. The IONPs/NSC hybrid coating achieved 99% antiviral activity within 5 min of contact, and all coatings exhibited 99.9999% antiviral activity against coronavirus within 24 h, while being nontoxic to L929 fibroblast cells after 24 h of exposure. The acute dermal toxicity of the IONPs/NSC hybrid system was evaluated in accordance with OECD guidelines 402, demonstrating safety for topical use. For this, animals were treated with topical applications of increasing doses of IONPs/NSC (1.5, 5, 14, and 40 mg/kg), benzalkonium chloride (750 mg/kg, toxic standard), and saline or white nanoparticle (WN, control group or a polymeric solution without IONPs). Compared to the control group, no clinical or histological changes were observed for the IONPs/NSC groups during the 14-day observation period. Conversely, benzalkonium chloride induced erythema, edema, and histological alterations in rat skin. These coatings show promise for use on protective equipment, with the aim to mitigate the risk of epidemics or pandemics.

Three tetraphenylethene molecular cage-based polymers with blue, yellow, and red emission (TCPBs, TCPYs, and TCPRs) were synthesized through successive atom transfer radical polymerization (ATRP) reactions. In an aqueous solution, they exhibit aggregation-induced emission effects, resulting in blue, yellow, and red fluorescence respectively. These polymers can be combined to create stable white light emissive hybrid nanoparticles (TCPWs) through Freud resonance energy transfer (FRET) effects. The resulting TCPWs demonstrate excellent fluorescence stability and can serve as fluorescent probes for long-term intracellular imaging for as long as 10 passages (20 days), outperforming single fluorescence emissive probes.

Surface-enhanced Raman scattering (SERS) is a promising, sensitive, and label-free molecule detection scheme. However, uniformity and reproducibility of signal enhancement have remained elusive, making quantitative evaluation difficult. In this work, we propose a simple fabrication approach to quantitative SERS sensors that satisfies all the sought-after characteristics: a gold hole-sphere nanogap SERS substrate that is uniform, reproducible, sensitive, large, and cost-effective. Here, we achieve a sensing uniformity of 4.2% averaged over 4 points throughout the entire 6-in. substrate and a SERS enhancement of 4.6 × 10⁸. Our approach provides for gap control in the vertical direction, thus granting very precise control with subnanometer accuracy and the statistical distribution of nanospheres in plane. This combination enables a remarkably uniform and reproducible SERS sensitivity over the entire substrate. The SERS spectra from DNA bases are also measured and their corresponding peaks are well defined down to 10 pM concentration. The proposed approach should be a key to quantitative SERS.

Selenomethionine (SeM) holds great potential applications in tumor therapy. However, the tumor-targeting ability of SeM in vivo remains challenging. Herein, we utilize extracellular vesicles (EV) as tumor-targeted drug delivery systems to achieve enhanced specific targeting and antitumor efficacy. The carboxyl groups of SeM are conjugated with the amino groups of EV derived from low-pH culture medium reprogrammed CT26 cells (LEV) to obtain the SeM-based formulations (SMLEV), which can actively target tumor cells and enhance uptake efficacy through specific behaviors of LEV to their parent cells. Mechanistic studies indicate that SMLEV can induce reactive oxygen species (ROS) overproduction, mitochondrial dysfunction, as well as Caspase-9 and Caspase-3 activation. Here, SMLEV exhibit enhanced cytotoxic potential toward colon tumor (CT26) cells. After systemic administration, the growth of tumors is inhibited in vivo using CT26 tumor-bearing mice. Our findings can provide insights and a strategy in developing SeM delivery for tumor treatment.

Molybdenum oxides and sulfides stand out as promising materials for chemiresistive gas sensors. In this study, we tailored MoS₂/MoO₂ heterostructures, adapting pyrolysis-assisted in situ sulfidation of hydrothermally grown MoO₃ by tuning the concentration of the sulfur source. The MoS₂ flakes adorning a MoO₂ cuboid rod heterostructure represent the n-type semiconducting property, confirmed by Hall measurement. Notably, the sensor demonstrated dual selectivity toward NH₃ and NO_x at room temperature. To our knowledge, the dual selectivity of the MoS₂/MoO₂ heterostructure has not been reported previously. The heterostructure, characterized by a higher carrier concentration, displayed enhanced sensitivity, yielding responses of 10.3 and 8.4% to 10 ppm of NH₃ and NO_x, respectively. The lowest detection limits were 0.32 ppm for NH₃ and 0.29 ppm for NO_x. Furthermore, the heterostructure sensor exhibited commendable cyclic stability and device reproducibility. A long-term stability assessment over 50 days revealed that the response of the sensor remained at 98.6 and 98.4% toward NH₃ and NO_x, respectively. Our results show that the optimized n–n heterojunction between MoO₂ and MoS₂ offers superior sensitivity to NH₃ and NO_x at room temperature. The results could have potential for the development of dual gas sensors suitable for real-time applications.

Heterogeneous multilayer configurations are discussed to enhance plasmonic hydrogen sensors (PHSs). Five sensor designs─pure Pd, Pd/Ag, Ag/Pd, Ag/Pd/Ag, and Pd/Ag/Pd─were developed by sequentially depositing Ag and Pd on nanosphere arrays. The Pd/Ag/Pd configuration demonstrated maximum 10, 2.7, and 1.69 times superior performances in rapid hydrogen sensing, signal detection, and reduced limit of detection (LOD) compared to pure Pd sensors. The impact of material composition, ambient interactions, intermaterial coupling, and surface morphology on sensitivity and response time was quantitatively analyzed using one-hot encoding and linear regression. Finite-difference time-domain (FDTD) calculations were employed to reveal the near-field surface plasmon resonance (SPR) effects. This study would offer theoretical insights and guiding principles for future PHS advancements, particularly in enhancing sensor performance through a heterogeneous multilayer configuration.

Taking advantage of the unique structural directionality of ionic liquids, we successfully synthesized highly concentrated gold nanoparticles (AuNPs) in 1-octyl-3-methylimidazolium chloride (OMImCl) using tetrabutylammonium borohydride (TBABH₄) as the reducing agent. It is a distinctly different approach, avoiding additional capping agents and producing spherical AuNPs of approximately 10 nm diameter at varying concentrations. To prevent nanoparticle aggregation during catalytic reactions and enhance catalyst reusability, these AuNPs were immobilized in cellulose films. The film fabrication involved blending each AuNP dispersion with microcrystalline cellulose dissolved in 1-butyl-3-methylimidazolium chloride (BMImCl) and further water regeneration. Therefore, these films, containing up to 1.30% AuNPs, efficiently reduced 4-nitrophenol (4-NP) using sodium borohydride. Remarkably, the catalysts remained effective through five cycles without noticeable degradation. Compared to other methods, our catalysts displayed a higher turnover frequency (TOF), especially in films with lower gold content, due to their smaller particle size and uniform distribution. Our approach, avoiding the need for complex recovery processes typical of powder-based catalysts, offers an environmentally friendly, efficient, and reusable solution, emphasizing its potential for robust catalytic applications.

Traditional pesticide emulsion formulation may exert deleterious effects on the environment and even induce stress on nontarget crops in the vicinity. In this study, γ-cyclodextrin (γ-CD)-encapsulated azobenzene derivative nanovesicles were synthesized and loaded with pendimethalin to obtain pendimethalin-loaded γ-CD/azobenzene derivative nanovesicles. Upon exposure to ultraviolet irradiation or sunlight, the azobenzene derivatives are converted from the trans- to cis- configuration, leading to the dissociation of the ternary host–guest complexes, resulting in the vesicle rupture and the subsequent release of pendimethalin. Further investigations were conducted on the γ-CD/azobenzene nanovesicles. According to the release characteristics of herbicides, the release rate of pendimethalin under ultraviolet light (365 nm) or sunlight conditions reached 88.3 ± 3%, which was 4.3 times higher than that under dark conditions, demonstrating excellent photocontrolled release behavior. Pot experiments showed that the herbicidal activity of pendimethalin-loaded nanovesicles against Portulaca oleracea (L.) and Echinochloa crusgalli (L.) Beauv. at the recommended dose was comparable to that of the pendimethalin technical under illuminated conditions. Furthermore, genotoxicity experiments reveal a notable increase in the mitotic index of onion root tip cells treated with pendimethalin-loaded nanovesicles, indicating that it had minimal inhibitory effect on cell metabolism and the genotoxicity was lower than that of pendimethalin technical. Pendimethalin-loaded nanovesicles exhibited favorable stability and photoresponsive performance. These findings reveal a promising avenue for responsive material design and release modulation using such nanovesicle systems, providing insights into their potential applications in targeted pesticide delivery systems.

The integration of plasmonic effects in nano electrocatalysis has emerged as a promising avenue for advancing biosensing and energy production technologies. Termed “direct plasmon-accelerated electrocatalysis (PAE)”, this innovative approach harnesses the synergistic interplay between plasmonic materials and electrocatalysts to enhance the efficiency and selectivity of electrochemical processes. By leveraging the unique optical properties of plasmonic nanoparticles, specifically localized surface plasmon resonance (LSPR), coupled with their ability to modulate the local electromagnetic field and promote hot charge transfer, this novel concept holds significant potential for driving advancements in biosensing applications and sustainable energy generation. Moreover, efficiency is ultimately and firmly dependent on the composition and structure of plasmonic metal nanomaterials and their surroundings. Scientists all over the world have done significant research, both theoretical and experimental, on how light interacts with metal nanoparticles to create stronger effects. This opens up a new challenge: combining this with nanoscale electrochemistry to make even more powerful applications. Within this article, we embark on a comprehensive exploration of the fundamental principles, intricate mechanisms, and the latest advancements in direct plasmon-accelerated electrocatalysis by gold nanostructures (Au NSs). Our aim is to provide a deeper understanding of how this technology extends its influence across diverse domains encompassing electrochemical reactions and biosensing applications enhanced by plasmonics. Additionally, we engage in a candid discussion regarding the persistent challenges and the promising avenues that lie ahead, painting a vivid picture of future opportunities in this exciting field.

We present CdSe@CdS nanorods coated with a redox-active polydopamine (PDA) layer functionalized with cobaloxime-derived photocatalysts for efficient solar-driven hydrogen evolution in aqueous environments. The PDA-coating provides reactive groups for the functionalization of the nanorods with different molecular catalysts, facilitates charge separation and transfer of electrons from the excited photosensitizer to the catalyst, and reduces photo-oxidation of the photosensitizer. X-ray photoelectron spectroscopy (XPS) confirms the successful functionalization of the nanorods with cobalt-based catalysts, whereas the catalyst loading per nanorod is quantified by total reflection X-ray fluorescence spectrometry (TXRF). A systematic comparison of different types of cobalt-based catalysts was carried out, and their respective performance was analyzed in terms of the number of nanorods and the amount of catalyst in each sample [turnover number, (TON)]. This study shows that the performance of these multicomponent photocatalysts depends strongly on the catalyst loading and less on the specific structure of the molecular catalyst. Lower catalyst loading is advantageous for increasing the TON because the catalysts compete for a limited number of charge carriers at the nanoparticle surface. Therefore, increasing the catalyst loading relative to the absolute amount of hydrogen produced does not lead to a steady increase in the photocatalytic activity. In our work, we provide insights into how the performance of a multicomponent photocatalytic system is determined by the intricate interplay of its components. We identify the stable attachment of the catalyst and the ratio between the catalyst and photosensitizer as critical parameters that must be fine-tuned for optimal performance.