Small-sized Nanoparticles Research Articles

Squeezing Out Nanoparticles from Perovskites: Controlling Exsolution with Pressure.

Nanoparticle exsolution has emerged as a versatile method to functionalize oxides with robust metallic nanoparticles for catalytic and energy applications. By modifying certain external parameters during thermal reduction (temperature, time, reducing gas), some morphological and/or compositional properties of the exsolved nanoparticles can be tuned. Here, it is shown how the application of high pressure (<100bar H2) enables the control of the exsolution of ternary FeCoNi alloyed nanoparticles from a double perovskite. H2 pressure affects the lattice expansion and the nanoparticle characteristics (size, population, and composition). The composition of the alloyed nanoparticles could be controlled, showing a reversal of the expected thermodynamic trend at 10 and 50bar, where Fe becomes the main component instead of Ni. In addition, pressure drastically lowers the exsolution temperature to 300°C, resulting in unprecedented highly-dispersed and small-sized nanoparticles with a similar composition to those obtained at 600°C and 10bar. The mechanisms behind the effects of pressure on exsolution are discussed, involving kinetic, surface thermodynamics, and lattice-strain factors. A volcano-like trend of the exsolution extent suggests that competing pressure-dependent mechanisms govern the process. Pressure emerges as a new design tool for metallic nanoparticle exsolution enabling novel nanocatalysts and surface-functionalized materials.

Ultrafine ruthenium-based nanoclusters regulated by a three-phase heterogeneous interface exhibiting superior mass activity for alkaline hydrogen evolution

Platinum-based catalysts are considered the most effective catalysts for the hydrogen evolution reaction (HER) in acidic media; however, they exhibit poor performance in alkaline electrolysis waters, which are currently more commercially developed, due to their sluggish water dissociation ability. Small-sized metal Ru nanoparticles, with metal-hydrogen bond strength close to Pt (approximately 65 kcal/mol) and a relatively lower water dissociation barrier, are considered one of the most promising alternatives to the noble metal Pt for alkaline HER. Based on the above statements, the present study innovatively combines the effective strategies of "heterogeneous interface engineering" and "construction of ultrafine active sites" to develop a highly efficient Ru-based catalyst with a three-phase heterogeneous interface, aiming to form its application in alkaline HER. Characterization analysis and DFT calculations demonstrated that the "Rux-Ni(OH)2NiO" three-phase heterogeneous interface constructed around ultrafine Rux clusters effectively modulated the electronic structure of the overall material and optimized the HER kinetic steps. This catalytic material, Rux@NOH/NO, exhibited outstanding electrocatalytic activity in alkaline HER, requiring only 44.2 mV to drive a current density of 10 mA·cm−2, with excellent long-term stability and extremely low active material loading (1.36 wt%-Ru). Specially, its mass activity reached an impressive 18,897.1 A/gRu at 150 mV, which is 10.2 times higher than that of commercial 20wt% Pt/C. In summary, this study synergistically constructs an ultrafine metal ruthenium-based catalyst based on a three-phase heterogeneous interface using a composite strategy, which provides an effective catalyst system for alkaline HER catalytic reactions and holds significance for the rational construction and design of efficient heterogeneous interface electrocatalysts.

Development of In Situ Methods for Preparing La-Mn-Co-Based Compounds over Carbon Xerogel for Oxygen Reduction Reaction in an Alkaline Medium.

Metal oxides containing La, Mn, and Co cations can catalyze oxygen reduction reactions (ORRs) in electrochemical processes. However, these materials require carbon support and optimal interactions between both compounds to be active. In this work, two approaches to prepare composites of La-Mn-Co-based compounds over carbon xerogel were developed. Using sol-gel methods, either the metal-based material was deposited on the existing carbon xerogel or vice versa. The metal oxide selected was the LaMn0.7Co0.3O3 perovskite, which has good catalytic behavior and selectivity towards direct ORRs. All the as-prepared composites were tested for ORRs in alkaline liquid electrolytes and characterized by diverse physicochemical techniques such as XRD, XPS, SEM, or N2 adsorption. Although the perovskite structure either decomposed or failed to form using those in situ methods, the materials exhibited great catalytic activity, which can be ascribed to the strengthening of the interactions between oxides and the carbon support via C-O-M covalent bonds and to the formation of new active sites such as the MnO/Co heterointerfaces. Moreover, Co-Nx-C species are formed during the synthesis of the metal compounds over the carbon xerogel. These species possess a strong catalytic activity towards ORR. Therefore, the composites formed by synthesizing metal compounds over the carbon xerogel exhibit the best performance in the ORR, which can be ascribed to the presence of the MnO/Co heterointerfaces and Co-Nx-C species and the strong interactions between both compounds. Moreover, the small nanoparticle size leads to a higher number of active sites available for the reaction.

Development of a rapid NO2 gas sensor based on SnO2 nanoparticles synthesized with glycine

Amino acids, as naturally occurring small molecules, have shown potential as materials for gas sensor-assisted synthesis. In this study, we present a novel method based on amino acid templates for the assisted synthesis of small-sized SnO2 nanoparticles at a low temperature of 140℃. Specifically, the Gly/SnO2-2 sample, synthesized with 20 % wt glycine incorporation, exhibited a sensitivity of 22.74 towards a low concentration (3 ppm) of NO2 under UV irradiation at 365 nm, with a rapid response/recovery time of 12/11 s. Remarkably, even under UV-free room-temperature conditions, the sensor continued to respond to NO2. Crystal structure analysis of the material was conducted through scanning electron microscopy (SEM) and transmission electron microscopy (TEM), revealing excellent crystallinity with a particle size of approximately 10 nm. Additionally, BET characterization indicated a well-defined spatial structure with a specific surface area of 58.17 m2/g. Experimental data further demonstrated that the Gly/SnO2-2 displayed good selectivity, reproducibility, and stability. These findings underscore the potential of amino acid templating in advancing gas sensing technologies, offering avenues for the development of highly efficient sensing materials.

Elucidating the effects of nitrogen and phosphorus co-doped carbon on complex spinel NiFe2O4 towards oxygen reduction reaction in alkaline media

The study presents for the first time complex spinel NiFe2O4 nanoparticles supported on nitrogen and phosphorus co-doped carbon nanosheets (NPCNS) prepared using sol gel and the carbonization of graphitic carbon nitride with lecithin as a highly active and durable electrocatalyst for oxygen reduction reaction. The physicochemical properties of complex spinel NiFe2O4 on NPCNS and subsequent nanomaterials were investigated using techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrochemical activity of the electrocatalysts was evaluated using hydrodynamic linear sweep voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. The electrocatalytic performance of the NiFe2O4/NPCNS nanohybrid electrocatalyst is dominated by the 4e− transfer mechanism, with an onset potential of 0.92 V vs. RHE, which is closer to that of the Pt/C, and a current density of 7.81 mA/cm2 that far exceeds that of the Pt/C. The nanohybrid demonstrated the best stability after 14 400 s, outstanding durability after 521 cycles, and the best ability to oxidize methanol and remove CO from its active sites during CO tolerance studies. This improved catalytic activity can be attributed to small nanoparticle sizes of the unique complex spinel nickel ferrite structure, N-Fe/Ni coordination of nanocomposite, high dispersion, substantial ECSA of 47.03 mF/cm2, and synergy caused by strong metal-support and electronic coupling interactions.

Restructuring and Hydrogen Evolution on Sub-Nanosized PdxBy Clusters.

As a Pt-group element, Pd has been regarded as one of the alternatives to Pt-based catalysts for the hydrogen evolution reaction (HER). Herein, we performed density functional theory (DFT) computations to explore the most stable structures of PdxBy (x = 6, 19, 44), revealed the in situ structural reconstruction of these clusters under acidic conditions, and evaluated their HER activity. We found that the presence of B can prevent underpotential hydrogen adsorption and activate the H atoms on the cluster surface for the HER. The theoretical calculations show that the reaction barrier for the HER on ~1 nm sized Pd44B4 can be as low as 0.36 eV, which is even lower than for the same-sized Pt and Pd2B nanoparticles. The ultra-high HER activity of sub-nanosized PdxBy clusters makes them a potential new and efficient HER electro-catalyst. This study provides new ideas for evaluating and designing novel nanocatalysts based on the structural reconstruction of small-sized nanoparticles in the future.

Single-Atom Alloy Formation via Reaction-Driven Catalyst Restructuring.

We demonstrate that single-atom alloy catalysts can be made by exposing physical mixtures of monometallic supported Cu and Pd catalysts to vinyl acetate (VA) synthesis reaction conditions. This reaction induces the formation of mobile clusters of metal diacetate species that drive extensive metal nanoparticle restructuring, leading to atomic dispersion of the precious metal, smaller nanoparticle sizes than the parent catalysts, and high activity and selectivity for both VA synthesis and ethanol dehydrogenation reactions. This approach is scalable and appears to be generalizable to other alloy catalysts.

Engagement of specific intracellular pathways in the inflammation-based reprotoxicity effect of small-size silver nanoparticles on spermatogonia and spermatocytes invitro cell models

Male infertility is a serious ongoing problem, whose causes have not yet been clearly identified. However, since human exposure to silver nanoparticles (AgNPs) has recently increased due to their beneficial properties, the present study aimed to determine the impact of small-size AgNPs on mouse spermatogonia (GC-1 spg) and spermatocytes [GC-2 spd(ts)] in vitro models as well as the ability of these nanostructures to induce inflammation. The results showed a significant dose- and time-dependent decrease in the metabolic activity in both cell models, which was correlated with an increase in the intracellular ROS level. Moreover, increased activity of caspase-9 and -3, together with enhanced expression of CASP3 and p(S15)-p53 proteins, was detected. Further studies indicated a decrease in ΔΨm after the AgNP-treatment, which proves induction of apoptosis with engagement of an intrinsic pathway. The PARP1 protein expression, the activity and protein expression of antioxidant enzymes, the GSH level, and the increased level of p-ERK1/2 indicate not only the engagement of DNA damage but also the occurrence of oxidative stress. The small-size AgNPs were able to induce inflammation, proved by increased protein expression of NF-κB, p-IκBα, and NLRP3, which indicate damage to spermatogonia and spermatocyte cells. Moreover, the PGC-1α/PPARγ and NRF2/Keap1 pathways were engaged in the observed effect. The spermatogonial cells were characterized by a stronger inflammation-based response to AgNPs, which may be correlated with the TNFα/TRAF2-based pathway. Summarizing, the obtained results prove that AgNPs impair the function of testis-derived cells by inducing the redox imbalance and inflammation process; therefore, these NPs should be carefully implemented in the human environment.

Surface plasmonic Au nanoparticles assisted CuO nanorods for broadband diverse ultrafast pulse generation

In virtue of the local surface plasmon resonance (LSPR) properties of metal nanoparticles to enhance the nonlinear optical response of the material, we successfully embed small-size Au nanoparticles into CuO nanorods. Then, theoretical and experimental methods verify that the assistance of ultrafast plasma response enhances the light-matter interaction. The LSPR characteristics and evanescent field distribution of the Au-CuO saturable absorber on the tapered fiber are studied by the finite element simulation method (FEM). By utilizing the Z-scan technology and twin-balanced detector system, excellent nonlinear optical (NLO) properties of the Au-CuO nanorods are demonstrated. Subsequently, depending on the remarkable nonlinear saturable absorption effect of Au-CuO, multiple operating states such as Q-switched, conventional soliton, double-subpulse soliton cluster, and noise-like pulse mode-locking are achieved in the erbium-doped fiber ring cavity at 1.5 μm. In addition, dual-wavelength mode-locking pulses with the center wavelengths of 1031 nm and 1035 nm are realized in the ytterbium-doped fiber ring cavity. This work describes an effective strategy to improve the NLO properties of CuO nanorods and indicates the great potential of Au-CuO in pulsed fiber lasers, opening a path for its application in ultrafast photonics and optoelectronics.

Mycotoxins: Their presence in food and relationship with nanoparticles

Mycotoxins are toxic compounds that are produced by certain fungi species; these compounds are found in many food products and may have detrimental effects on the health of human beings and livestock. Mycotoxins spoilage in food triggers both short-term and long-term effects including upset stomachs, liver, kidney, and neurological disorders. Typically used inspection methods for determination of mycotoxins in foods are cumbersome, tedious, and can sometimes give out inaccurate results. Therefore, there is a need for improvement in the approaches used for early detection of mycotoxins and the control of mycotoxin contamination in foods. As for the fourth direction, we can pinpoint nanotechnology for the detection of mycotoxin and their prevention as a promising field of study. When manipulated for use in food, the small size, geometry and surface characteristics of nanoparticles can be used to improve the detection and elimination of mycotoxins in foods. To date, implementation of nanoparticles in food safety is rather limited; however, the potentials of the technology have been highlighted by the existing studies. For instance, some current research has ascertained that nanoparticles are capable of adsorbing mycotoxins so that these toxins are easily separated from the food products. Also, nanoparticles can also be applied for the purpose of degrading or neutralizing mycotoxin.

In Situ Aggregated Nanomanganese Enhances Radiation-Induced Antitumor Immunity.

Radiosensitizers play a pivotal role in enhancing radiotherapy (RT). One of the challenges in RT is the limited accumulation of nanoradiosensitizers and the difficulty in activating antitumor immunity. Herein, a smart strategy was used to achieve in situ aggregation of nanomanganese adjuvants (MnAuNP-C&B) to enhance RT-induced antitumor immunity. The aggregated MnAuNP-C&B system overcomes the shortcomings of small-sized nanoparticles that easily flow back into blood vessels and diffuse into surrounding tissues, and it also prolongs the retention time of nanomanganese within cancer cells and tumors. The MnAuNP-C&B system significantly enhances the radiosensitization effect in RT. Additionally, the pH-responsive disassembly of MnAuNP-C&B triggers the release of Mn2+, further promoting RT-induced activation of the STING pathway and eliciting robust antitumor immunity. Overall, our study presents a smart strategy wherein in situ aggregation of nanomanganese effectively inhibits tumor growth through radiosensitization and the activation of antitumor immunity.

Effect of precursor concentration, surfactant and temperature on the size, morphology and nanostructure of zero-valent iron nanocrystals synthesised by a polyol route

Iron metal nanoparticles, due to their magnetic properties, reducing power and low toxicity, have numerous applications not only in groundwater and contaminated soil remediation but also in biomedicine as contrast agents in magnetic resonance imaging. However, obtaining this nanomaterial involves the use of strongly reducing, polluting and expensive reagents and high temperatures. Herein, the use of ethylene glycol and diethylene glycol in a strong alkaline medium that allows the direct reduction of iron(II) salts to iron(0) in the absence of any added reducer has been analysed for preparation of well-defined nanoparticles. The key roles of the polyhydroxylated surfactants (D-mannitol, D-mannose, polyvinyl alcohol and polyvinyl pyrrolidone) were identified, and their efficiencies were evaluated. In addition, conclusions have been drawn regarding the existence of a minimum temperature required for the reduction of the precursor, as well as the observation that the size of the nanoparticles increases with reaction temperature. The main result is that by combining surfactants and controlling the reaction temperature, pure cubic iron(0) nanoparticles smaller than 100 nm were obtained, thereby reducing the formation of hydroxylated by-products. The high reactivity, high magnetic response, long-term stability and small size of the iron nanoparticles produced in this work will allow their use in various applications.

A transformable and self-oxygenated smart probe for enhanced tumor sonodynamic therapy

Sonodynamic therapy (SDT) is emerging as a promising modality for cancer treatment. However, improving the tumor bioavailability and anti-hypoxia capability of sonosensitizers faces a big challenge. In this work, we present a tumor microenvironment (TME)-mediated nanomorphology transformation and oxygen (O2) self-production strategy to enhance the sonodynamic therapeutic efficacy of tumors. A smart probe Ce6-Leu@Mn2+ that consists of a glutathione (GSH) and leucine amino peptidase (LAP) dual-responsive unit, a 2-cyanobenzothiazole (CBT) group, and a Mn2+-chelated Ce6 as sonosensitizer for tumor SDT was synthesized, and its SDT potential for liver tumor HepG2 in living mice was systematically studied. It was found that the probes could self-assemble into large nanoparticles in physiological condition and spontaneously transformed into small particles under the dual stimulation of GSH and LAP in TME resulting in enhanced tumor accumulation and deep penetration. More notably, Ce6-Leu@Mn2+ could convert endogenous hydrogen peroxide to O2, thereby alleviating the hypoxia and achieving effective SDT against hypoxic tumors under the excitation of ultrasound. We thus believe this smart TME-responsive probe may provide a noninvasive and efficient means for malignant tumor treatment. Statement of significanceSonodynamic therapy (SDT) is emerging as a promising therapeutic modality for cancer treatment. However, how to improve the tumor bioavailability and anti-hypoxia capability of sonosensitizers remains a huge challenge. Herein, we rationally developed a theranostic probe Ce6-Leu@Mn2+ that can transform into small-size nanoparticles from initial large particles under the dual stimulation of LAP and GSH in tumor microenvironment (TME) resulting in enhanced tumor accumulation, deep tissue penetration as well as remarkable O2 self-production for enhanced sonodynamic therapy of human liver HepG2 tumor in living mice. This smart TME-responsive probe may provide a noninvasive and efficient means for hypoxic tumor treatment.

Engineering of ceramic membranes with superhydrophobic pores for different size water droplets removal from water-in-oil emulsions

Superhydrophobic (SHB) ceramic membrane surfaces have proved their superiority in water-in-oil (W/O) emulsion separation. However, the construction of ceramic membranes with SHB pores remains challenging and the interaction between the SHB pores and water droplets is still unclear. Herein, by growing uniform ZnO nanoclusters (NCs) onto the SiC grains of a symmetric SiC ceramic membrane and then grafting with triethoxy(octyl)silane, a series of ZnO NCs@SiC membranes with SHB pores were prepared. Prior to secondary hydrothermal synthesis ZnO NCs, the small-sized ZnO nanoparticles (NPs) were grown onto the SiC grains via a sol–gel process. All the ZnO NCs@SiC membranes with SHB pores showed improved water removal performance from W/O emulsions compared with that of the pristine membrane. The optimal membrane with SHB pores displayed a pore size of 0.19 μm with a water contact angle of 163.96°. The smaller water droplets in W/O emulsions, the membrane pores are easier to be polluted. When separating a 1000 ppm W/O emulsion with a water droplet size of 500 nm at a transmembrane pressure of 0.5 bar, the water rejection reached 98.90 %, and the steady-state oil flux was 92.99 L·m−2·h−1. Based on the separation experiments, the separation mechanism was revealed. This work provides significant perceptions into constructing SHB pores of ceramic membranes, which might be useful for other possible applications.

A Uni-Micelle Approach for the Controlled Synthesis of Monodisperse Gold Nanocrystals.

Small-size gold nanoparticles (AuNPs) are showing large potential in various fields, such as photothermal conversion, sensing, and medicine. However, current synthesis methods generally yield lower, resulting in a high cost. Here, we report a novel uni-micelle method for the controlled synthesis of monodisperse gold nanocrystals, in which there is only one kind micelle containing aqueous solution of reductant while the dual soluble Au (III) precursor is dissolved in oil phase. Our synthesis includes the reversible phase transfer of Au (III) and "uni-micelle" synthesis, employing a Au (III)-OA complex as an oil-soluble precursor. Size-controlled monodisperse AuNPs with a size of 4-11 nm are synthesized by tuning the size of the micelles, in which oleylamine (OA) is adsorbed on the shell of micelles and enhances the rigidity of the micelles, depressing micellar coalescence. Monodisperse AuNPs can be obtained through a one-time separation process with a higher yield of 61%. This method also offers a promising way for the controlled synthesis of small-size alloy nanoparticles and semiconductor heterojunction quantum dots.

Flexible Ni‐Based Bimetallic Spinel Oxide (NiM2O4, M = Mn, Fe, Co) Electrodes for Supercapacitor Applications

Herein, the single‐phase Ni‐based bimetallic spinel oxide (NiM2O4, M = Mn, Fe, Co) nanoparticles are successfully synthesized by sol–gel method and coated on a carbon cloth substrate to form flexible electrodes for supercapacitor applications. The effects of transition metal activity, calcination temperature, surface, and textural properties on the electrochemical properties of spinel electrode materials are demonstrated. It is found that lowering the calcination temperature results in a decrease in crystallite size and particle size, leading to an increase in surface area and pore volume. X‐Ray absorption spectroscopy reveals the presence of Mn2+/3+, Fe2+/3+, and Co2+/3+ in materials. According to the electrochemical studies, NiMn2O4 electrode in Na2SO4 electrolyte exhibits electrical double‐layer capacitance behavior, while NiFe2O4 and NiCo2O4 electrodes in KOH electrolyte exhibit pseudocapacitive behavior. All electrode materials have low solution resistance and charge transfer resistance. NiCo2O4 provides the highest specific capacitance (85.60 F g−1 at 2.5 A g−1) followed by NiFe2O4 and NiMn2O4. It seems likely that the high electrochemical activity of Co2+/3+ and small particle size of NiCo2O4 nanoparticles play an important role in improving the redox process and charge transfer, which may enhance the electrochemical performance of this electrode material.

Tracking epithelial-mesenchymal transition in breast cancer cells based on a multiplex electrochemical immunosensor

Epithelial-mesenchymal transition (EMT) promotes tumor cell infiltration and metastasis. Tracking the progression of EMT could potentially indicate early cancer metastasis. A key characteristic of EMT is the dynamic alteration in the molecular levels of E-cadherin and N-cadherin. Traditional assays have limited sensitivity and multiplexing capabilities, relying heavily on cell lysis. Here, we developed a multiplex electrochemical biosensor to concurrently track the upregulation of N-cadherin expression and reduction of E-cadherin in breast cancer cells undergoing EMT. Small-sized gold nanoparticles (Au NPs) tagged with redox probes (thionin or amino ferrocene) and bound to two types of antibodies were used as distinguishable signal tags. These tags specifically recognized E-cadherin and N-cadherin proteins on the tumor cell surface without cross-reactivity. The diphenylalanine dipeptide (FF)/chitosan (CS)/Au NPs (FF-CS@Au) composites with high surface area and good biocompatibility were used as the sensing platforms for efficiently fixing cells and recording the dynamic changes in electrochemical signals of surface proteins. The electrochemical immunosensor allowed for simultaneous monitoring of E- and N-cadherins on breast cancer cell surfaces in a single run, enabling tracking of the EMT dynamic process for up to 60 h. Furthermore, the electrochemical detection results are consistent with Western blot analysis, confirming the reliability of the methodology. This present work provides an effective, rapid, and low-cost approach for tracking the EMT process, as well as valuable insights into early tumor metastasis.

Photocatalytic CO2 methanation over the Ni/SiO2 catalysts for performance enhancement

CO2 methanation produces synthetic natural gas, which reduces CO2 emission and generates sustainable energy. Exploring effective approach and developing high performance Ni catalysts are the main focus for the reaction. In this study, we report photocatalytic methanation over Ni/SiO2 catalysts. Through physicochemical properties of BET, XRD, H2-TPR and TEM, optical properties of UV–visual light absorbance and light-illuminated H2-TPR, and the performance of photocatalytic methanation, the structure-performance relationship is tentatively discussed. The strong absorbance of light, the small size of Ni nanoparticles and the strong metal-support interaction of the Ni/SiO2 catalysts, as well as the low activation energy of CH4 production, are correlated to the enhanced photocatalytic performance compared to the conventional catalytic performance. The photocatalytic pathway of methanation on Ni nanoparticles are suggested to understand the enhanced performance. The work demonstrates the higher photocatalytic methanation performance than conventional catalytic methanation, which is applicable for other reactions using photo-sensitive catalysts.

Optimization of lignin precipitation from black liquor using organic acids and its valorization by preparing lignin nanoparticles

This work focuses on the precipitation of lignin from kraft black liquor (BL) along with its valorization into lignin nanoparticles (LNP). Two organic acids namely, acetic acid, and lactic acid were used for the precipitation of lignin as an alternative to sulfuric acid. An optimization study was carried out to determine the effect of three key variables, namely acid type, temperature, and pH, on the isolation yield and purity of lignin. The study showed that all factors primarily influenced the lignin yield, while the purity of precipitated lignin varied only around 1 % between minimum to maximum purity. Further, the acid precipitation method was selected for the preparation of LNP. The study aimed to observe the effect of pH, lignin concentration, and surfactant concentration over the properties of the prepared nanoparticles. The results showed that a smaller nanoparticle size and maximization of phenolic content was achieved with a lignin concentration of 35 mg/mL, a surfactant concentration of 10 % (w/w lignin), and a pH of 5. Additionally, the antibacterial activity of LNPs against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa bacteria was evaluated. The results showed only minor activity against Staphylococcus aureus. Overall, the study demonstrates the potential method for precipitation and valorization of lignin through the production of LNP with desirable properties.

Ultra-small gold nanoparticles embedded cyclodextrin metal-organic framework composite membrane to achieve antibacterial and humidity-responsive functions

Cyclodextrin metal-organic framework (CD-MOF) is an edible and porous material that can serve as a template for synthesizing small-sized metal nanoparticles. However, its highly hydrophilic nature has limited its wider application. Herein, ultra-small gold nanoparticles (U-AuNPs) were loaded into CD-MOF to produce a composite material Au@CD-MOF. The CD-MOF was utilized as a template to control the size of the AuNPs. The synthesized Au@CD-MOF was easily dispersible in aqueous medium and its released U-AuNPs exhibited effective water dispersion stability within 120 days. Additionally, compared to gold nanoparticles prepared using traditional methods (T-AuNPs), the U-AuNPs exhibited superior antibacterial properties. Furthermore, hydrophilic Au@CD-MOF was incorporated into a hydrophobic polydimethylsiloxane (PDMS) matrix (Au@CD-MOF/PDMS) to achieve a humidity-responsive antibacterial function. The composite membrane exhibited remarkable responsiveness to humidity, showing almost no release of U-AuNPs at 0 % humidity. However, it exhibited approximately 89 % release within 1 h, and complete release of U-AuNPs was observed within 4 h under 100 % humidity. These findings highlight the successful preparation of a humidity-responsive antibacterial composite membrane, which has great potential applications in various scenarios, particularly in the field of antibacterial food packaging.