Ultrasmall Size Research Articles

AI-based tree modeling for multi-point dioxin concentrations in municipal solid waste incineration

Numerous investigations have shown that the municipal solid waste incineration (MSWI) has become one of the major sources of dioxin (DXN) emissions. Currently, the primary issue that needs to be addressed for DXN emission reduction control is the online measurement of DXN. Data-driven AI algorithms enable real-time DXN concentration measurement, facilitating its control. However, researchers mainly focus on building models for DXN emissions at the stack. This approach does not allow for the construction of models that online measurement of DXN generation and absorption throughout the whole process. To achieve optimal pollution control, models that encompass the whole process are necessary, not just models focused on the stack. Therefore, this article focuses on modeling the whole process of DXN concentrations, including generation, adsorption, and emission. It uses machine learning techniques based on advanced tree-based data-driven deep and broad learning algorithms. The determination of data characteristics at different phases is grounded in the understanding of the DXN mechanism, offering a novel framework for DXN modeling. State-of-the-art tree-based models, including adaptive deep forest regression algorithm based on cross layer full connection, tree broad learning system, fuzzy forest regression, and aid modeling technologies, are applied to handle diverse data characteristics. These characteristics encompass high-dimensional small samples, low-dimensional ultra-small size samples, and medium-dimensional small samples across different phases related to DXN. The most interesting is the robust validation where the proposed a whole process tree-based model for DXN is validated using nearly one year of authentic data on DXN generation, adsorption, and emission phases in an MSWI plant of Beijing. The proposed modeling framework can be used to explore the mechanism characterization and support the pollution reduction optimal control.

Asymmetric bi-level dual-core mode converter for high-efficiency and polarization-insensitive O-band fiber-chip edge coupling: breaking the critical size limitation.

Efficient coupling between optical fibers and on-chip photonic waveguides has long been a crucial issue for photonic chips used in various applications. Edge couplers (ECs) based on an inverse taper have seen widespread utilization due to their intrinsic broadband operation. However, it still remains a big challenge to realize polarization-insensitive low-loss ECs working at the O-band (1,260-1,360 nm), mainly due to the strong polarization dependence of the mode coupling/conversion and the difficulty to fabricate the taper tip with an ultra-small feature size. In this paper, a high-efficiency and polarization-insensitive O-band EC is proposed and demonstrated with great advantages that is fully compatible with the current 130-nm-node fabrication processes. By introducing an asymmetric bi-level dual-core mode converter, the fundamental mode confined in the thick core is evanescently coupled to that in the thin core, which has an expanded mode size matched well with the fiber and works well for both TE/TM-polarizations. Particularly, no bi-level junction in the propagation direction is introduced between the thick and thin waveguide sections, thereby breaking the critical limitation of ultra-small feature sizes. The calculated coupling loss is 0.44-0.56/0.48-0.61 dB across the O-band, while achieving 1-dB bandwidths exceeding 340/230 nm for the TE/TM-polarization modes. For the fabricated ECs, the peak coupling loss is ∼0.82 dB with a polarization dependent loss of ∼0.31 dB at the O-band when coupled to a fiber with a mode field diameter of 4 μm. It is expected that this coupling scheme promisingly provides a general solution even for other material platforms, e.g., lithium niobate, silicon nitride and so on.

Sub−1 nm Nanowire Aerogels

AbstractThe emerging sub−1 nm nanowires (SNWs) have received tremendous attention given their intriguing properties and broad applications attributable to their ultrasmall feature size. However, applying SNWs in microstructure‐preserving macroscopic functional materials (e.g., aerogels) remains challenging because the solvents used for preparing SNWs are not compatible with conventional supercritical drying or freeze‐drying techniques. In this study, the fabrication of SNW aerogels (SNWAs) is pioneered by developing a nonpolar solvent‐based freeze‐casting strategy. Cyclohexane, a nonpolar solvent with a freezing point (6.5 °C) comparable to that of water, is selected as a reaction and drying medium to assemble various SNWs. The resulting self‐standing SNWAs display low density, excellent hydrophobicity and lipophilicity, and tunable luminescent color. This strategy not only introduces a new aggregation form of SNWs but also provides a creative perspective on synthesizing aerogel structures from sub−1 nm building blocks.

Ultrasmall-sized light-emitting diodes fabricated by ion implantation based on GaN epitaxial wafers with fully activated or unactivated p-GaN.

A key challenge in realizing ultrahigh-resolution displays is the efficient preparation of ultrasmall-sized (USS) light-emitting diodes (LEDs). Today, GaN-based LEDs are mainly prepared through dry etching processes. However, it is difficult to achieve efficient and controllable etching of USS LED with high aspect ratios, and LED sidewalls will appear after etching, which will have a negative impact on the device itself. Herein, a method for preparing USS LED based on GaN epitaxial wafers is reported (on two types of wafers, i.e., with p-GaN fully activated and unactivated). F-ions are injected into the intentionally exposed areas on the two types of wafers to achieve device isolation. The area under the micro-/nano-sized protective masks (0.5, 0.8, 1, 3, 5, 7, 9, and 10 µm wide Ni/Au stripes) are the LED lighting areas. The LED on the p-GaN unactivated wafer (UAW) requires further activation. The Ni/Au mask not only serves as the p-electrode of LED but also Ni as a hydrogen (H) removing metal covering the surface of p-GaN UAW that can desorb H from a Mg element in the film at relatively low temperatures, thereby achieving the selective activation of LED lighting areas. Optoelectronic characterization shows that micro-/nano-sized LED arrays with individual-pixel control were successfully fabricated on the two types of wafers. It is expected that the demonstrated method will provide a new way toward realizing ultrahigh-resolution displays. Analyzing the changes in the current flowing through LED (before and after selective activation) on the F-injected p-GaN UAW, it is believed that depositing H removing metal on p-GaN UAW could possibly realize the device array through the selective activation only (i.e., without the need for ion implantation), offering a completely new insight.

Highly Anion‐Conductive Viologen‐Based Two‐Dimensional Polymer Membranes as Nanopower Generators

AbstractTwo‐dimensional polymers (2DPs) and their layer‐stacked 2D covalent organic frameworks (2D COFs) membranes hold great potential for harvesting sustainable osmotic energy. The nascent research has yet to simultaneously achieve high ionic flux and selectivity, primarily due to inefficient ion transport dynamics. This is directly related to ultrasmall pore size (<3 nm), much smaller than the duple Debye length in the diluted electrolyte (6–20 nm), as well as low charge density (<4.5 mC m−2). Here, we introduce a π‐conjugated viologen‐based 2DP (V2DP) membrane possessing a large pore size of 4.5 nm, strategically enhancing the overlapping of the electric double layer, coupled with an exceptional positive surface charge density (~6 mC m−2). These characteristics enable the membrane to facilitate high anion flux while maintaining ideal selectivity. Notably, V2DP membranes realize an impressive current density of 5.5×103 A m−2, surpassing benchmarks set by previously reported nanofluidic membranes. In the practical application scenario involving the mixing of artificial seawater and river water, the V2DP membranes exhibit a considerable ion transference number of 0.70 towards Cl−, contributing to an outstanding power density of ~55 W m−2. Theoretical calculations reveal the important role of the large quantity of anion transport sites, which act as binding sites evenly located in the positively charged N‐containing pyridine rings. These binding sites enable kinematic coupling and decoupling between anions and the V2DP skeleton, establishing a continuous Cl− ion transport pathway. This work demonstrates the great promise of large‐area ultrathin 2DP membranes featuring highly organized charged ion transport networks when applied for osmotic energy conversion.

Neuronal Membrane-Derived Nanodiscs for Broad-Spectrum Neurotoxin Detoxification.

Neurotoxins pose significant challenges in defense and healthcare due to their disruptive effects on nervous tissues. Their extreme potency and enormous structural diversity have hindered the development of effective antidotes. Motivated by the properties of cell membrane-derived nanodiscs, such as their ultrasmall size, disc shape, and inherent cell membrane functions, here, we develop neuronal membrane-derived nanodiscs (denoted "Neuron-NDs") as a countermeasure nanomedicine for broad-spectrum neurotoxin detoxification. We fabricate Neuron-NDs using the plasma membrane of human SH-SY5Y neurons and demonstrate their effectiveness in detoxifying tetrodotoxin (TTX) and botulinum toxin (BoNT), two model toxins with distinct mechanisms of action. Cell-based assays confirm the ability of Neuron-NDs to inhibit TTX-induced ion channel blockage and BoNT-mediated inhibition of synaptic vesicle recycling. In mouse models of TTX and BoNT intoxication, treatment with Neuron-NDs effectively improves survival rates in both therapeutic and preventative settings. Importantly, high-dose administration of Neuron-NDs shows no observable acute toxicity in mice, indicating its safety profile. Overall, our study highlights the facile fabrication of Neuron-NDs and their broad-spectrum detoxification capabilities, offering promising solutions for neurotoxin-related challenges in biodefense and therapeutic applications.

Ultrafine IrNi nanoparticles supported onto titanium nitride as low-iridium and highly active OER electrocatalysts for proton exchange membrane water electrolysis

The development of cost-effective and highly efficient iridium-based catalysts for the anode of proton exchange membrane water electrolyzers (PEMWEs) is urgently required. This study utilized a straightforward wet-chemical method to produce IrNi nanoparticles that were supported on titanium nitride (TiN), where the ultra-small particle size of 1.9 nm for IrNi nanoparticles and the structural support provided by TiN ensure the full exposure of catalytic sites. The electronic interaction between Ir-Ni and Ir-TiN enhances the intrinsic activity of the catalytic sites. The developed catalyst exhibits excellent oxygen evolution reaction (OER) performance, with an overpotential of just 267 mV at a current density of 10 mA cm−2, and a mass activity of 1.07 A mgIr−1 at 1.55 V versus reversible hydrogen electrode, which is more than 14 times that of commercial IrO2. Furthermore, its catalytic performance is validated in a PEMWE single cell, along with stable operation for 100 h. The proposed design of the supported iridium-based alloy catalysts in this study presents a novel and referential method for developing anode catalysts in PEMWEs.

A single-microbe living bioelectronic sensor for intracellular amperometric analysis

Subcellularly amperometric analysis in situ is crucial for understanding intracellular redox biochemistry and subcellular heterogeneity. Unfortunately, the ultra-small size and complex microenvironment inside the cell pose a great challenge to achieve this goal. To address the challenge, a minimized living microbial sensor has been fabricated in this work for amperometric analysis. Here, by fabricating the dimidiate microelectrode as the working electrode, while fitting a living electroactive bacterium (EAB) as the transducer, outward extracellular electron transfer (EET) of the sensory EAB is correlated with the concentration of lactic acid, which is electrochemically recorded and thus displays an electrical signal output for detection. In specific, the S. oneidensis modified dimidiate microelectrode (S.O.@GNE-NPE) acts as an integrated electroanalytical device to generate the electrical signal in situ. The established microcircuit provides unprecedented precision and sensitivity, contributing to subcellular amperometric measurement. The microbial sensor shows a linear response in the concentration range of 0–60 mM, with a limit of detection (LOD) at 0.3 mM. The microsensor also demonstrates good selectivity against interferences. Additionally, intracellular analysis of lactic acid provides direct evidence of enhanced lactic metabolism in cancer cells as a result of “Warburg Effect”. This work shows an example of nano-, bio- and electric technologies that have been integrated on the EAB-modified dimidiate microelectrode, and achieves intracellular biosensing application through such integration. It may give a new strategy on the combination of micro/nanotechnologies with sensory EAB for the necessary development of bioelectronic devices.

Hierarchical mesoporous Co3O4@C-N nanostructure rods derived from a metal-organic framework as high-performance anode for lithium-ion battery

A uniform hierarchical mesoporous Co3O4@C-N nanostructure rods were in situ fabricated successfully by developing a facile one-step strategy. Cobalt-based metal organic framework [Co3(ndc)(HCOO)3(μ-OH)(H2O)]n with special Co chine constructed framework structure treated as a precursor directly pyrolyzed in a mixed atmosphere of argon and oxygen (95:5) at 500 °C for 2 h. According to the XRD pattern, SEM, TEM, EDS mapping images and XPS spectrum analysis, the well-defined hierarchical mesoporous Co3O4@C-N nanostructure rods showed pure Co3O4 phase, are assembled from a large number of core–shell structured Co3O4@C-N spherical particles with an ultrasmall and uniform size (∼8 nm) which were further connected by N doped carbon net to form nanostructure rods. Using as anode material for lithium-ion batteries, these hierarchical mesoporous Co3O4@C-N nanostructure rods exhibit excellent electrochemical performance with high reversible capacity, rate capability and good cycling stability. They maintained a reversible specific capacity of more than 1000 mAh/g at 100 mA/g, and the discharge specific capacities at the 5 current density of 0.1, 0.2, 0.5, 1, 2, and 5 A/g reached 1123, 1094, 1044, 979, 879 and 688 mAh/g, respectively.

Copper nanoclusters derived from copper phthalocyanine as real active sites for CO2 electroreduction: Exploring size dependency on selectivity ‐ A mini review

AbstractThe electrochemical reduction reaction of CO2 (CO2RR) holds promise for converting CO2 into valuable fuels and chemicals, particularly when powered by renewable electricity, thereby aiding in reducing atmospheric CO2 levels and addressing climate change. Copper phthalocyanine and its derivatives (Cu‐Pcs) have attracted significant attention as versatile electrocatalytic materials with high selectivity toward various hydrocarbon products. However, the real active sites of Cu‐Pcs for different products vary, and there is a lack of comprehensive summary. To address this gap, we analyze and summarize previous research, yielding the following insights: Cu‐Pcs undergo reconstruction and demetallization during CO2RR, with Cu(II) converting to Cu(0), forming transient copper nanoclusters (Cu NCs). The selectivity for CO2RR products closely correlates with the size of those derived Cu NCs. Specifically, reversible Cu NCs with ultrasmall sizes (≤2 nm), which revert to Cu‐Pcs after electrolysis, exhibit high selectivity toward CH4. As Cu NCs increase in size, there is a higher CO coverage, promoting CO generation. When Cu NCs exceed a critical threshold size (approximately 15 nm), C‐C coupling can occur, facilitating the formation of multicarbon (C2+) products. Furthermore, the structure of macrocycles, types of functional groups, and properties of carbon substrates influence the size and electron density of Cu NCs, thereby impacting the selectivity of CO2RR products.

Increased Cytotoxicity of Bimetallic Ultrasmall Silver-Platinum Nanoparticles (2 nm) on Cells and Bacteria in Comparison to Silver Nanoparticles of the Same Size.

Ultrasmall nanoparticles (diameter 2 nm) of silver, platinum, and bimetallic nanoparticles (molar ratio of Ag:Pt 0:100; 20:80; 50:50; 70:30; 100:0), stabilized by the thiolated ligand glutathione, were prepared and characterized by transmission electron microscopy, differential centrifugal sedimentation, X-ray photoelectron spectroscopy, small-angle X-ray scattering, X-ray powder diffraction, and NMR spectroscopy in aqueous dispersion. Gold nanoparticles of the same size were prepared as control. The particles were fluorescently labeled by conjugation of the dye AlexaFluor-647 via copper-catalyzed azide-alkyne cycloaddition after converting amine groups of glutathione into azide groups. All nanoparticles were well taken up by HeLa cells. The cytotoxicity was assessed with an MTT test on HeLa cells and minimal inhibitory concentration (MIC) tests on the bacteria Escherichia coli and Staphylococcus xylosus. Notably, bimetallic AgPt nanoparticles had a higher cytotoxicity against cells and bacteria than monometallic silver nanoparticles or a physical mixture of silver and platinum nanoparticles. However, the measured release of silver ions from monometallic and bimetallic silver nanoparticles in water was very low despite the ultrasmall size and the associated high specific surface area. This is probably due to the surface protection by a dense layer of thiolated ligand glutathione. Thus, the enhanced cytotoxicity of bimetallic AgPt nanoparticles is caused by the biological environment in cell culture media, together with a polarization of silver by platinum.

High-performance electrocatalyst for PEMFC cathode: Combination of ultra-small platinum nanoparticles and N-doped carbon support

To accelerate the implementation of zero-emission power installations based on proton-exchange membrane fuel cells, it is necessary to maximize the power characteristics of these devices. For this purpose, we have obtained and tested a new N-doped carbon support and a synthesized Pt/C catalyst based on it with a platinum loading of about 37.3 %. A comparison of the degradation resistance of the initial support and the N-doped one has shown greater stability of the latter. At the same time, Raman spectroscopy has confirmed the presence of the C–N bond, which indicates the successful doping of carbon with nitrogen. The resulting Pt/C catalyst based on an N-doped support is characterized by a substantially narrow size dispersion and an ultra-small nanoparticle size of about 2.6 nm. The high-angle annular dark-field scanning transmission electron microscopy images of the synthesized catalyst have confirmed the presence of individual platinum atoms/clusters uniformly distributed over the surface of the support, and their presence is due to nitrogen embedded into the carbon structure. This material is characterized by a 50 m2 gPt-1 larger electrochemically active surface area and a 227 A gPt-1 greater mass activity compared to the commercial JM40 analog (40 % platinum loading). Meanwhile, the electrochemical parameters remaining after the accelerated stress testing are almost 2 times higher than those of JM40. And the power characteristics in the membrane electrode assembly for the catalyst synthesized by the facile one-pot synthesis method are 13 % (575 mW cm-2) higher than those of the commercial analog (500 mW cm-2). The Pt/C catalyst obtained during the research is deemed promising for commercial use in proton-exchange membrane fuel cells.

Silver peroxide-incorporated carbon dots with high photothermal performance for combating bacteria

The widespread use of antibiotics often increases bacterial resistance. Herein, we reported a silver peroxide-incorporated carbon dots (defined as Ag2O2–CDs) with high photothermal conversion efficiency via in situ oxidation process. The prepared Ag2O2–CDs exhibited ultra-small size of 2.0 nm and hybrid phase structure. Meanwhile, the Ag2O2–CDs were of a similar optical performance comparing with traditional carbon dots (CDs). Importantly, the incorporation of Ag2O2 into CDs significantly enhanced photothermal conversion efficiency from 3.8% to 28.5%. By combining silver ion toxicity and photothermal ablation, the Ag2O2–CDs were capable of destroying gram-positive and gram-negative bacterium effectively. These findings demonstrated that the Ag2O2–CDs could be served as a potential antibacterial agent for clinical applications.

All-organic nanocomposite with strong photo-pyroelectric response and its application in retinal prosthesis

In patients with retinal degenerative diseases, vision restoration is feasible through implanted artificial retinal prostheses to stimulate surviving neurons. Photoelectric composites based on ferroelectric polymers have been attempted to construct retinal prostheses. However, these materials normally have a low photoelectric response and a narrow response wavelength range. Here, we synthesize conjugated poly-Schiff base nanoparticles with ultra-small size, and the nanocomposites of the nanoparticles and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric polymer generate a high photoelectric response (maximum peak-to-peak voltage > 90 V) under visible and near-infrared light. This flexible all-organic nanocomposite has good biocompatibility and can establish effective signal transduction with neuron cells. We explored the use of composites to construct ferroelectric retinal prostheses. Electrophysiological tests and animal behavior analysis have preliminary shown that implanted retinal prostheses can restore the visible light sensitivity of blind rats and further endow them with the ability to perceive infrared light, demonstrating their potential application in bioelectronics. This work presents a novel all-organic ferroelectric polymer composite with flexibility, biocompatibility, and excellent photoelectric response that can be used for artificial retinal prostheses. The nanocomposite composed of ultra-small conjugated nanoparticles and ferroelectric P(VDF-TrFE) exhibits excellent photo-pyroelectric response under visible and infrared light, with a peak-to-peak voltage exceeding 90 V. The ultra-thin retinal prostheses (∼ 20 µm) constructed from this nanocomposite can directly stimulate nerve cells, effectively restore the visual function of blind rats, and endow them with infrared light sensitivity.

Ultra-Small High-Entropy Alloy as Multi-Functional Catalyst for Ammonia Based Fuel Cells.

Ammonia fuel cells using carbon-neutral ammonia as fuel are regarded as a fast, furious, and flexible next-generation carbon-free energy conversion technology, but it is limited by the kinetically sluggish ammonia oxidation reaction (AOR), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER). Platinum can efficiently drive these three types of reactions, but its scale-up application is limited by its susceptibility to poisoning and high cost. In order to reduce the cost and alleviate poisoning, incorporating Pt with various metals proves to be an efficient and feasible strategy. Herein, PtFeCoNiIr/C trifunctional high-entropy alloy (HEA) catalysts are prepared with uniform mixing and ultra-small size of 2 ± 0.5nm by Joule heating method. PtFeCoNiIr/C exhibits efficient performance in AOR (Jpeak = 139.8 A g-1 PGM), ORR (E1/2 = 0.87V), and HER (E10 = 20.3 mV), outperforming the benchmark Pt/C, and no loss in HER performance at 100mA cm-2 for 200 h. The almost unchanged E1/2 in the anti-poisoning test indicates its promising application in real fuel cells powered by ammonia. This work opens up a new path for the development of multi-functional electrocatalysts and also makes a big leap toward the exploration of cost-effective device configurations for novel fuel cells.

Ultra-small size and crystal-axis-oriented BaTiO3 nanocrystals: Dielectric and photocatalytic response

With the development of modern nanotechnology, the application range of BaTiO3 (BT) materials has been expanded, and the design and synthesis of micro-nano scale BT materials have become one of the hot spots. In this study, ultra-small BaTiO3 (Ultra-BT) were prepared by solvothermal-calcination reaction. First, the BT precursor was prepared by solvothermal reaction with ethylene glycol as solvent, and then the BT precursor was calcined to obtain Ultra-BT. The Ultra-BT at this time is composed of uniform [010]-crystal-axis-oriented BT nanocrystals with a size of about 28 nm. The formation mechanism of Ultra-BT was revealed, namely the dissolution-deposition reaction. Ultra-BT are more favorable for the preparation of BT ceramics with uniform grain because of their ultra-small size. At a sintering temperature of 1220 °C, the dielectric constant of BT ceramics at the Curie temperature is 8661. This dielectric constant value is higher than that reported for BT ceramics in most literature, and even higher than some doped modified BT ceramics. The solvothermal-calcination method used for preparing Ultra-BT provides important reference value for the preparation of other ultra-small perovskite materials. At the same time, because of the excellent dielectric properties and good catalytic properties of Ultra-BT, it has potential application value in the field of dielectric and catalysis.

A near-infrared naphthalocyanine photosensitizer with superior light absorption and renal clearance for type-I photodynamic and photothermal combination therapy

Currently, it is still a challenge to develop an organic photosensitizer (PS) with outstanding near-infrared absorption, low O2 dependence, precise tumor targeting and rapid clearance through the kidney to improve the overall outcome of phototherapy. In this study, we have designed an organic PS (NcPB) with an excellent near-infrared light absorption through a refined molecular strategy. Meanwhile, NcPB was assembled into nanoparticles with different sizes (NanoNcPB-1 and NanoNcPB-0) by a supramolecular modulation strategy. As the results, the nanoparticle with an ultra-small size (NanoNcPB-1) generated a large number of superoxide anion (O2•−) in a low-O2-dependent manner and release plenty of heat. Furthermore, the results of in vivo experiments demonstrated that NanoNcPB-1 actively accumulated in tumor tissues and showed a 92% tumor inhibition after photodynamic and photothermal combination therapy. More importantly, NanoNcPB-1 could be rapidly cleared from the body of mice via the renal pathway, which alleviates potential side effects of prolonged retention of PS in the circulation.

Ultra-Small Size Micro-LEDs With Enhanced Efficiency for Near-Eye Display

Ultra-Small Size Micro-LEDs With Enhanced Efficiency for Near-Eye Display

Antibiotic Alternatives: Multifunctional Ultra-Small Metal Nanoclusters for Bacterial Infectious Therapy Application.

The prevalence of major bacterial infections has emerged as a significant menace to human health and life. Conventional treatment methods primarily rely on antibiotic therapy, but the overuse of these drugs has led to a decline in their efficacy. Moreover, bacteria have developed resistance towards antibiotics, giving rise to the emergence of superbugs. Consequently, there is an urgent need for novel antibacterial agents or alternative strategies to combat bacterial infections. Nanoantibiotics encompass a class of nano-antibacterial materials that possess inherent antimicrobial activity or can serve as carriers to enhance drug delivery efficiency and safety. In recent years, metal nanoclusters (M NCs) have gained prominence in the field of nanoantibiotics due to their ultra-small size (less than 3 nm) and distinctive electronic and optical properties, as well as their biosafety features. In this review, we discuss the recent progress of M NCs as a new generation of antibacterial agents. First, the main synthesis methods and characteristics of M NCs are presented. Then, we focus on reviewing various strategies for detecting and treating pathogenic bacterial infections using M NCs, summarizing the antibacterial effects of these nanoantibiotics on wound infections, biofilms, and oral infections. Finally, we propose a perspective on the remaining challenges and future developments of M NCs for bacterial infectious therapy.

The disruptive effect on the bacterial cell wall explored of the ultrasmall particle-sized Ag nanoparticles supported with Zn Cu-based hybrid nanoagents

The smaller the particle size of Ag nanoparticles, the higher their antibacterial activity against drug-resistant strains, and the greater their potential for application in living organisms. Therefore, preparing Ag nanoparticles with ultra-small particle sizes has become one of the greatest challenges at present. In this study, 1.75 nm Ag was uniformly anchored on the surface of a highly biocompatible carrier to synthesize Fe3O4/ZnO@Cu2S@Ag (FCA) nanocomposites. The antibacterial activity and mechanism of FCA were investigated, and the material was used to treat wound infections caused by bacteria. At a concentration of 175 μg/mL, the antibacterial rate of Escherichia coli, Staphylococcus aureus, and drug-resistant Salmonella was over 99.99 % within 45 min. The antibacterial activity is mainly composed of •OH and multiple cations. The antibacterial mechanism involves •OH and multiple cations synergistically targeting and damaging the bacterial cell wall, altering the secondary structure of the bacterial cell wall, leading to leakage of bacterial contents and bacterial death. Additionally, FCA exhibited high biocompatibility, curing bacterial infections within 7 days and completely eliminating bacterial burden. These findings elucidate the role of antibacterial activity in composite antibacterial materials and suggest that FCA has clinical application potential in treating bacterial infections.