Nm In Diameter Research Articles

NET-inducing diamond nanoparticles with adsorbed hydrophobic SARS-CoV-2 antigens serving as vaccine candidate

This study addresses the current need for vaccine adjuvants able to induce an immune response to novel or mutated pathogens. It exploits the ability of nanodiamonds (ND) to induce the formation of neutrophil extracellular traps (NETs) triggering inflammation, accompanied by immune response to co-injected antigens. Hydrophobic nanodiamonds 10 nm in diameter were covered with 194 a.a. sequence of the receptor-binding domain of Spike protein of SARS-CoV-2 via passive adsorption. It was shown that antigen-covered ND induce activation of human neutrophils and stimulate NETs formation and ROS production. When used for immunization antigen-covered ND induced long-lasting immune response in mice with prevailing IgG1 among antibody subclasses. The injected nanoparticles were sequestered by NETs and safely covered with connective tissues when examined 1 year after injection. Keywords: adjuvants, IgG1, nanodiamonds, neutrophil extracellular traps, ROS, S-protein, SARS-COV-2, vaccine

Nanoscale dosimetry for a radioisotope-labeled metal nanoparticle using MCNP6.2 and Geant4.

Metal nanoparticles (MNPs) labeled with radioisotopes (RIs) are utilized as radio-enhancers due to their ability to amplify the radiation dose in their immediate vicinity. A thorough understanding of nanoscale dosimetry around MNPs enables their effective application in radiotherapy. However, nanoscale dosimetry around MNPs still requires further investigation. This study aims to provide insight into the radio-enhancement effects of MNPs by elucidating nanoscale dosimetry surrounding MNPs labeled with Auger-emitting RIs. We particularly focus on distinguishing the respective dose contributions of photons and electrons emitted by Auger-emitting RIs in the context of dose enhancement. A 50nm diameter NP of silver (Ag) core and gold (Au) shell (Ag@Au NP) was assumed to emit mono-energetic electrons and photons (3, 5, 10, 20, and 30keV), or the energy spectrum corresponding to one of three Auger-emitting RIs (103Pd, 125I, and 131Cs) from the Ag core. Nanoscale radial dose distributions around a single radioactive Ag@Au NP were evaluated in spherical shells of water. Monte Carlo simulations were conducted using single-event and track structure transport methods implemented in MCNP6.2 and Geant4-DNA-Au physics, respectively. To evaluate the extent of radio-enhancement by the Ag@Au NP, two scenarios were considered: Ag@Au NPs (Au shell included) and Ag@water NPs (Au shell replaced by water). The radial doses of 10, 20, and 30keV electrons estimated by both codes were comparable. However, the radial doses of 3 and 5keV electrons by MCNP6.2 were much larger near the NP surface than those by Geant4. There was a dose enhancement of a few % to tens % by the Au shell in the region of the NP surface to 10µm, depending on the electron energy. The radial doses of photons with the Au shell were higher up to their secondary electron ranges than those without the Au shell. The maximum dose enhancement factor of photons occurred at 20keV and was 63.4 by MCNP6.2 and 50.5 by Geant4. The overall radial doses of electrons were 1-2 orders of magnitude larger than those of photons. As a result, in cases of RIs emitting both electrons and photons, the radial doses up to electron ranges were dominantly governed by electrons. The dose enhancement estimated by both codes for the RIs ranged from a few % except in the immediate vicinity of the NP surface. Given the dominant contribution of electrons to radial doses of MNP labeled with Auger-emitting RIs, physical dose enhancement expected by interactions with photons was hindered. Since there are no available RIs emitting exclusively photons, achieving enhanced physical doses within a cell through a combination of MNPs and RIs appears currently unattainable. The radial doses of photons near the NP surface exhibited considerable discrepancies between the codes, primarily attributed to low-energy electrons. The difference may arise from higher cross-sections of Au inelastic scattering in Geant4-DNA-Au compared to MCNP6.2.

Uncovering the membrane and pore formation mechanisms of the lysozyme membrane made via the amyloid-like assembly

Biomimetic protein membranes have attracted increasing interests because of their distinctive separation properties in the membrane field. Low-cost and stable protein lysozyme has been intensively invetigated to fabricate high-performance sepration membranes via a facile and scalable method of amyloid-like assembly. However, the pore formation mechnism of the lysozyme membrane remains unclear. Herein, the lysozyme membranes were fabricated and the membrane formation mechnism and separation properties were investigated experimentally. Molecular dynamics simulation (MDS) was also employed to reveal the pore formation mechanism of the lysozyme membrane. The fabricated lysozyme membrane achieved a stable high water permeance of 10.2 L m−2 h−1 bar−1, as well as a relatively high separation factor (9.5) towards antibiotic and sodium chloride. MDS results found that the membrane pore size is governed by the amino acid compositions and is negatively dependent on the intermolecular forces among amino acids around the pores. Selective pores with 0.54 nm in diameter are primarily formed by these amino acids including alanine (35 %), aspartic acid (25 %), arginine (15 %), phenylalanine (11 %), and lysine (7 %), in which half of them have hydrophobic side chains with no charge, and another half have hydrophilic side chains with balanced charges. This work may stimulate the development of highly permeable and selective protein membranes by carefully engineering their amino acid compositions with optimal charges and hydrophobicity for generation of numerous selective pores.

Lipid organization by the Caveolin-1 complex

Caveolins are lipid-binding proteins that can organize membrane remodeling and oligomerize into the 8S complex. The CAV1-8S complex comprises a disk-like structure, about 15 nm in diameter, with a central beta barrel. Further oligomerization of 8S complexes remodels the membrane into caveolae vessels, with a dependence on cholesterol concentration. However, the molecular mechanisms behind membrane remodeling and cholesterol filtering are still not understood. Performing atomistic molecular dynamics simulations in combination with advanced sampling techniques, we describe how the CAV1-8S complex bends the membrane and accumulates cholesterol. Here, our simulations show an enhancing effect by the palmitoylations of CAV1, and we predict that the CAV1-8S complex can extract cholesterol molecules from the lipid bilayer and accommodate them in its beta barrel. Through backmapping to the all-atom level, we also conclude that the Martini v.2 coarse-grained force field overestimates membrane bending, as the atomistic simulations exhibit only very localized bending.

Effect of starch molecular weight on the colon-targeting delivery and promoting GLP-1 secretion of starch-lecithin complex nanoparticles

β-lactoglobulin (β-LG) could stimulate enteroendocrine L cells which are located in the colon to secrete glucagon-like peptide-1 (GLP-1) to maintain glycemic homeostasis. In order to ensure that β-LG can intactly arrive in the colon through oral administration, colon-targeting delivery systems should be engineered. In this study, β-LG encapsulated nanoparticles were fabricated through molecular interaction and self-assembly using octenyl succinic anhydride (OSA) modified potato starch-lecithin complex (OPC) with different starch molecular weight (Mw). OPC with lower starch Mw exhibited stronger interaction with β-LG and its correspondent nanoparticles showed smaller diameter and higher structural compactness. Obtained OPC based nanoparticles were spherical, of Z-average diameter from 139.9 nm to 246.8 nm, of zeta-potential from −1.94 mV to −9.42 mV and of α value from 1.41 to 2.14. Additionally, OPC based nanoparticles with lower starch Mw exhibited excellent capacity for maintaining structure integrality in simulated upper gastrointestinal tract (GIT) environment. Optimized OPC based nanoparticles with 224.4 nm of diameter, −9.00 mV of zeta-potential and 2.14 of α value had well mucus-penetrating capacity (59.25%) and colon-targeting capacity (49.18% released in simulated colonic fluid). Moreover, the OPC based nanoparticles passed through the upper GIT signally stimulated GLP-1 secretion (improved 119.23%) primarily through β-LG targeting released in colon in the prophase and short-chain fatty acids and reducing sugar produced by colonic microbial degradation of OPC in the later phase. Altogether, OPC based nanoparticles have great potential of mucus penetrating and colon-targeting delivery systems for use in stimulating GLP-1 secretion which can support applications for maintaining glycemic homeostasis.

Registration of activity of a single molecule of horseradish peroxidase using a detector based on a solid-state nanopore.

This work demonstrates the use of a solid-state nanopore detector to monitor the activity of a single molecule of a model enzyme, horseradish peroxidase (HRP). This detector includes a measuring cell, which is divided into cis- and trans- chambers by a silicon nitride chip (SiN structure) with a nanopore of 5 nm in diameter. To entrap a single HRP molecule into the nanopore, an electrode had been placed into the cis-chamber; HRP solution was added into this chamber after application of a negative voltage. The reaction of the HRP substrate, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), oxidation by the enzyme molecule was performed in the presence of hydrogen peroxide. During this reaction, the functioning of a single HRP molecule, entrapped in the nanopore, was monitored by recording the time dependence of the ion current flowing through the nanopore. The approach proposed in our work is applicable for further studies of functioning of various enzymes at the level of single molecules, and this is an important step in the development of single-molecule enzymology.

Prepared gold-modified hollow nanosphere Co3O4/rGO composites for low concentration H2S gas detection

In this paper, Au-modified Co3O4 hollow nanospheres/graphene composites (Au-Co3O4/rGO) were synthesized for the first time through a novel “one-pot cooking” method at ambient temperature. The hollow nanospheres exhibited a particle size of approximately 10–15 nm, while the modified Au nanoparticles were about 4–5 nm in diameter. A high-efficiency and high response H2S gas sensor was constructed based on Au-Co3O4/rGO ternary composites. The effects of different Au modifying mass ratios on the H2S gas-sensitive performance of the composites were systematically investigated. At an operational temperature of 92 °C, the Au-Co3O4/rGO sensor, incorporating an Au loading mass ratio of 1.3 wt%, exhibited a response value of 175.4 for H2S at 100 ppm, a recovery time of 30 s, and a detection limit reaching as low as 10 ppb. This response was tripled compared to the undoped Co3O4/rGO sensor. At the same time, the H2S sensing mechanism by Au-Co3O4/rGO was discussed in detail.

Biosintesis Nanopartikel ZnO dengan Ekstrak Temu Kunci (Boesenbergia rotunda) Dibantu Gelombang Mikro, Serta Pengujian Aktivitasnya Terhadap Bakteri

Numerous ZnO nanoparticles have been successfully synthesized using diverse plant extracts, yet research utilizing B. rotunda extract as a capping agent with microwave assistance has been lacking. Hence, this study aimed to employ microwave-assisted B. rotunda extract to produce ZnO nanoparticles and test their antibacterial activity. By utilizing 10 mL of 1% (m/v) B. rotunda extract at pH 12.5 and calcinating for 3.8 hours at 200°C, coupled with 20 minutes of microwave treatment, ZnO nanoparticles averaging 78.78 nm in diameter were synthesized. Particle size was determined using the ImageJ software to analyze TEM images. UV-Vis absorption spectroscopy indicated a peak wavelength at 360 nm, while FTIR analysis identified compounds from B. rotunda extract crucial in nanoparticle formation. Antibacterial testing revealed the nanoparticles' ability to create an inhibition zone against E. coli growth.

Viromics reveals two novel viruses of the family Closteroviridae in Codiaeum variegatum plant with leaf variegation symptoms.

Codiaeum variegatum is a valuable ornamental plant with distinct bright yellowing and golden spots on dark green leaves, which resemble virus symptoms. To investigate the factors, especially viral agents, associated with the variegated leaf color of Codiaeum variegatum, we performed virome profiling of a single C. variegatum 'Gold Dust' leaf sample collected from Hainan, China using ribosomal RNA-depleted total RNA sequencing on an Illumina NovaSeq 6000 platform. Two novel viruses, with two variants each, belonging to the family Closteroviridae were detected and characterized: Croton golden spot-associated virus C variants 1 and 2 (CGSaVC-v1, and CGSaVC-v2) of the genus Crinivirus and Croton golden spot-associated virus A variants 1 and 2 (CGSaVA-v1 and CGSaVA-v2) of the genus Ampelovirus. Transmission electron microscopy showed long, flexuous, filamentous virus particles approximately 15 nm in diameter and 760-770 nm in length. Molecular screening of ninety-seven variegated individual plant leaves showed a high prevalence of CGSaVA-v1 (90.7%), CGSaVA-v2 (75.3 %), CGSaVC-v1 (70.1%), and CGSaVC-v2 (47.4%), while asymptomatic leaves near the meristem tip were mostly free of the target viruses. To our knowledge, this is the first study to demonstrate the significant association between closterovirids and the golden spots. The findings provide novel insights into the genetic diversity of the family Closteroviridae and inform future germplasm conservation and new cultivar development of Codiaeum Variegatum.

Fast Reaction of the Prussian Blue Based Nanozyme "Artificial Peroxidase" with the Substrates: Pre-Steady-State Kinetic Approach.

This letter introduces the pre-steady-state kinetic approach, which is traditional for evaluation of elementary constants in molecular (enzyme) catalysis, for nanozymes. Apparently, the most active peroxidase-mimicking nanozyme based on catalytically synthesized Prussian Blue nanoparticles has been chosen. The elementary constants (k1) for the nanozymes' reduction by an electron-donor substrate (being the fastest stage according to steady-state kinetic data) have been determined by means of stopped-flow spectroscopy. These constants have been found to be dependent on both the size of the nanozyme and the reducing substrate redox potential. For the smallest nanozymes (32 nm in diameter), log(k1) linearly decays with an increase of the substrate redox potential (cotangent value ≈125 mV). On the contrary, for the largest nanozymes with a diameter above 150 nm, k1 is almost independent of it. Moreover, for the substrate with the lowest redox potential (K4[Fe(CN)6]), the rate constant under discussion (k1) is almost independent of the nanozymes' size. Perhaps, the rate of the intrananozyme electron transfer causing bleaching becomes comparative or even lower than that of the nanoparticle interaction with the fastest substrate. Anyway, the elementary constant of nanozyme reduction with potassium ferrocyanide (k1) reaches the value of 1 × 1010 M-1 s-1, which is 3-4 orders of magnitude faster than for enzymes peroxidases. The obtained results obviously demonstrate that the pre-steady-state kinetic approach is able to discover novel advantages of nanozymes from both fundamental and practical points of view.

Formation Mechanism and Hydrothermal Synthesis of Highly Active Ir1-xRuxO2 Nanoparticles for the Oxygen Evolution Reaction.

Iridium dioxide (IrO2), ruthenium dioxide (RuO2), and their solid solutions (Ir1-xRuxO2) are very active electrocatalysts for the oxygen evolution reaction (OER). Efficient and facile synthesis of nanosized crystallites of these materials is of high significance for electrocatalytic applications for converting green energy to fuels (power-to-X). Here, we use in situ X-ray scattering to examine reaction conditions for different Ir and Ru precursors resulting in the development of a simple hydrothermal synthesis route using IrCl3 and KRuO4 to obtain homogeneous phase-pure Ir1-xRuxO2 nanocrystals. The solid solution nanocrystals can be obtained with a tunable composition of 0.2 < x < 1.0 and with ultra-small coherently scattering crystalline domains estimated from 1.3 to 2.6 nm in diameter based on PDF refinements. The in situ X-ray scattering data reveal a two-step formation mechanism, which involves the initial loss of chloride ligands followed by the formation of metal-oxygen octahedra clusters containing both Ir and Ru. These octahedra assemble with time resulting in long-range order resembling the rutile structure. The mixing of the metals on the atomic scale during the crystal formation presumably allows the formation of the solid solution rather than heterogeneous mixtures. The size of the final nanocrystals can be controlled by tuning the synthesis temperature. The facile hydrothermal synthesis route provides ultra-small nanoparticles with activity toward the OER in acidic electrolytes comparable to the best in the literature, and the optimal material composition very favorably combines low overpotential, high mass activity, and increased stability.

Regulatory roles of extracellular polymeric substances in uranium reduction via extracellular electron transfer by Desulfovibrio vulgaris UR1

The pathway of reducing U(VI) to insoluble U(IV) using electroactive bacteria has become an effective and promising approach to address uranium-contaminated water caused by human activities. However, knowledge regarding the roles of extracellular polymeric substances (EPS) in the uranium reduction process involving in extracellular electron transfer (EET) mechanisms is limited. Here, this study isolated a novel U(VI)-reducing strain, Desulfovibrio vulgaris UR1, with a high uranium removal capacity of 2.75 mM/(g dry cell). Based on a reliable EPS extraction method (45 °C heating), manipulation of EPS in D. vulgaris UR1 suspensions (removal or addition of EPS) highlighted its critical role in facilitating uranium reduction efficiency. On the second day, U(VI) removal rates varied significantly across systems with different EPS contents: 60.8% in the EPS-added system, 48.5% in the pristine system, and 22.2% in the EPS-removed system. Characterization of biogenic solids confirmed the reduction of U(VI) by D. vulgaris UR1, and the main products were uraninite and UO2 (2.88–4.32 nm in diameter). As EPS formed a permeable barrier, these nanoparticles were primarily immobilized within the EPS in EPS-retained/EPS-added cells, and within the periplasm in EPS-removed cells. Multiple electroactive substances, such as tyrosine/tryptophan aromatic compounds, flavins, and quinone-like substances, were identified in EPS, which might be the reason for enhancement of uranium reduction via providing more electron shuttles. Furthermore, proteomics revealed that a large number of proteins in EPS were enriched in the subcategories of catalytic activity and electron transfer activity. Among these, iron-sulfur proteins, such as hydroxylamine reductase (P31101), pyruvate: ferredoxin oxidoreductase (A0A0H3A501), and sulfite reductase (P45574), played the most critical role in regulating EET in D. vulgaris UR1. This work highlighted the importance of EPS in the uranium reduction by D. vulgaris UR1, indicating that EPS functioned as both a reducing agent and a permeation barrier for access to heavy metal uranium.

Preparation and Characterization of 1D, 2D, and 3D Shapes of Anisotropic Gold Nanoparticles

In recent times, the scientific community has become interested in gold nanoparticles, namely in the anisotropic class. Based on their shapes, they fall into three categories: one-, two-, and three-dimensional. The synthesis and properties of three different anisotropic gold nanoparticle preparations - gold nanobipyramids (one-dimension, 1D), gold nanoprisms (two-dimension, 2D), and gold stars (three-dimension, 3D) - are shown in this research. Here, our group describes a chemical reduction method mediated by seeds. X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, and ultraviolet-visible spectroscopy were used to analyze the anisotropic gold nanoparticles. The average dimensions of the nanobipyramids were 64.27 ± 7.31 nm for length and 25.87 ± 2.56 nm for diameter, according to the data; the average dimensions of the gold nanoprisms and goldstars were 43.54 ± 5.61 nm and 31.35 ± 7.01 nm, respectively. Furthermore, following centrifugation purification, the yields of triangle and bipyramidal particles rose from 40% to over 60% and from 60% to 90%, respectively. It was established what the ideal parameter concentration was to create anisotropic gold nanoparticles in three dimensions: one, two, and three.

Up-Conversion Emissions from HfO2: Er3+, Yb3+ Nanoparticles Synthesized by the Hydrothermal Method.

Up-conversion emission from HfO2 nanoparticles, as a host lattice, doped with Er3+ and Yb3+ ions and codoped with alkaline cations Li+ and Na+ obtained. The HfO2 nanoparticles, about 80 nm in diameter, were synthesized by the hydrothermal method at 200 °C for 1.3 h, and an additional heat treatment at 1000 °C was necessary to ensure the dopants incorporation into the host lattice. These nanoparticles were studied by means of XRD, Raman Spectroscopy, SEM, EDS, PL, CL, and up-conversion luminescence. First, the doping was performed with Er3+ ions in different percentages. The photoluminescence and cathodoluminescence studies showed an inefficient emission, and only at 7 at % Er3+ ions, the sample presented emissions at 522, 545, and 656 nm corresponding to the transitions of the Er3+ ions. So, codoping was carried out, and HfO2: Er3+/Yb3+ generated an efficient conversion process. The atom percentage of Yb3+ ions was fixed (7 at % Yb3+), and the Er3+ content was varied, showing the highest emission intensity at 3 at % Er3+ ions. Subsequently, the up-conversion emission intensity was optimized by varying the percentage of Yb3+ ions and keeping the Er3+ ion content fixed (3 at %). Adding cations such as Na+ and Li+ in different percentages, a notable improvement of the up-conversion emission intensities in the HfO2: Er3+/Yb3+ nanoparticles was obtained. The up-conversion emission bands observed were located at ∼523 and 544 nm, corresponding to the electronic transitions 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2, respectively. While the bands at ∼652 and 673 nm correspond to the transition 4F9/2 → 4I15/2, respectively. The excitation of these materials with infrared radiation (980 nm) produced noticeable emission bands in the red spectral range, whereas excitation with accelerated electrons (CL) generated prominent bands in the green region.

Biological Effects of Green Synthesized Al-ZnO Nanoparticles Using Leaf Extract from Anisomeles indica (L.) Kuntze on Living Organisms.

The synthesis of Al-ZnO nanoparticles (NPs) was achieved using a green synthesis approach, utilizing leaf extract from Anisomeles indica (L.) in a straightforward co-precipitation method. The goal of this study was to investigate the production of Al-ZnO nanoparticles through the reduction and capping method utilizing Anisomeles indica (L.) leaf extract. The powder X-ray diffraction, UV spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy with EDAX analysis were used to analyze the nanoparticles. X-ray diffraction analysis confirmed the presence of spherical structures with an average grain size of 40 nm in diameter, while UV-visible spectroscopy revealed a prominent absorption peak at 360 nm. FTIR spectra demonstrated the presence of stretching vibrations associated with O-H, N-H, C=C, C-N, and C=O as well as C-Cl groups indicating their involvement in the reduction and stabilization of nanoparticles. SEM image revealed the presence of spongy, spherical, porous agglomerated nanoparticles, confirming the chemical composition of Al-ZnO nanoparticles through the use of the EDAX technique. Al-ZnO nanoparticles showed increased bactericidal activity against both Gram-positive and Gram-negative bacteria. The antioxidant property of the green synthesized Al-ZnO nanoparticles was confirmed by DPPH radical scavenging with an IC50 value of 23.52 indicating excellent antioxidant capability. Green synthesized Al-ZnO nanoparticles were shown in in vivo studies on HeLa cell lines to be effective for cancer treatment. Additionally, α-amylase inhibition assay and α-glucosidase inhibition assay demonstrated their potent anti-diabetic activities. Moving forward, the current methodology suggests that the presence of phenolic groups, flavonoids, and amines in Al-ZnO nanoparticles synthesized with Anisomeles indica (L.) extract exhibit significant promise for eliciting biological responses, including antioxidant and anti-diabetic effects, in the realms of biomedical and pharmaceutical applications.

Zinc oxide nanoparticles cause hepatotoxicity in rare minnow (Gobiocypris rarus) via ROS-mediated oxidative stress and apoptosis activation and inhibition of lipid peroxidation

Zinc oxide nanoparticles (ZnO NPs) measuring 30 ± 10 nm in diameter are utilized in various applications, including batteries, plastics, ceramics, cosmetics, flame retardants, and food. However, their potential impact and risk on aquatic ecosystems remain unclear. This study examined the hepatotoxic effects of dietary ZnO NPs in rare minnow. Three hundred rare minnows were fed diets containing 0 mg/kg, 20 mg/kg and 60 mg/kg of ZnO NPs for 60 days, with hepatotoxicity assessments at 15-day intervals. The histological data showed that ZnO NPs severely damage liver tissues, causing cytoplasmic vacuolization and irregular or missing nuclei. The treatment groups showed a significant rise in the liver injury index (P < 0.05). Moreover, there was a notable increase in zinc accumulation in the ZnO NPs groups compared to the control group (P < 0.05). ZnO NPs also reduced body weight and hepato-somatic index (HSI) in rare minnows. The enzyme activity results showed elevated levels of reactive oxygen species (ROS), total cholesterol (T-CHO), triglyceride (TG), acetyl Coa carboxylase (ACC), and fatty acid synthase (FAS) in the ZnO NPs fed groups, while total antioxidant capacity (T-AOC) and malondialdehyde (MDA) decreased. Further investigation found that accumulation of ZnO NPs in the liver tissues up-regulated the levels of genes related to antioxidant (mn-sod, cat and nf-κb), pro-apoptotic (bax) and lipogenesis (gpat3, dgat1a and dgat1b), while down-regulating genes associated with lipid catabolism (cpt1 and tpi1). These findings suggest that dietary ZnO NPs cause hepatotoxicity by inducing oxidative stress through ROS, triggering apoptosis, and inhibiting lipid peroxidation. The results indicate that ZnO NPs may pose a significant threat to aquatic animals and ecosystems.

Surface-Enhanced Raman Scattering on Size-Classified Silver Nanoparticles Generated by Laser Ablation.

This study delved into the complex interplay between the nanostructural characteristics of nanoparticles and their efficacy in surface-enhanced Raman scattering (SERS) for sensitive detection of trace chemical substances. Silver nanoparticles were prepared for the SERS substrate by combining laser ablation, postannealing processes (up to 500 °C), and electrostatic mobility classification, allowing high-purity silver nanoparticles with controlling their sizes (40-100 nm) and aggregate structures. These nanoparticles were then inertially deposited on the substrates to create SERS-active surfaces, employing Rhodamine B as a probe to assess the impact of particle size, shape, and deposition density on SERS effectiveness. Our findings revealed that spherical nanoparticles, especially those approximately 50 nm in diameter, controlled to a spherical structure through gas-phase annealing at 500 °C and subsequent classification, yielded the most significant SERS enhancement. This optimal can be explained by the particle size response of the surface plasmon resonance, where the enhancement of the Raman signal for particles up to 50 nm (1/10 of the laser wavelength used in this study, 532 nm) arises from a balance between the enhancement of dipole moment and the number of "hot spot" regions (respectively proportional to the cube and inverse square of the diameters in theory, leading to a linear relationship between signal intensity and particle diameter); meanwhile, in larger size region than 50 nm, the Raman signal was decreased owing to the attribution of the phase difference between the electric field and dipole moment. Furthermore, we found that a deposition density of 2 μg resulted in nearly a single layer of particles, which is crucial for maximizing SERS hotspots and, consequently, the enhancement effect.

Formation of Nanodiamonds during Pyrolysis of Butanosolv Lignin.

The preparation of artificial diamonds has a long history driven by decreased costs compared to naturally occurring diamonds and ethical issues. However, fabrication of diamonds in the laboratory from readily available biomass has not been extensively investigated. This work demonstrates a convenient method for producing nanodiamonds from biopolymer lignin at ambient pressure. Lignin was extracted from Douglas Fir sawdust using a butanosolv pretreatment and was pyrolyzed in N2 at 1000 °C, followed by a second thermal treatment in 5% H2/Ar at 1050 °C, both at ambient pressure. This led to the formation of nanodiamonds embedded in an amorphous carbon substrate. The changes occurring at various stages of the pyrolysis process were monitored by scanning electron microscopy, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. High resolution transmission electron microscopy revealed that nanodiamond crystallites, 4 nm in diameter on average, formed via multiple nucleation events in some carbon-containing high density spheres. It is proposed that highly defected graphene-like flakes form during the pyrolysis of lignin as an intermediate phase. These flakes are more deformable with more localized π electrons in comparison with graphene and join together face-to-face in different manners to form cubic or hexagonal nanodiamonds. This proposed mechanism for the formation of nanodiamonds is relevant to the future fabrication of diamonds from biomass under relatively mild conditions.

Dual-functional emulsifier based nano-emulsion adjuvant effectively enhanced immunogenicity of recombinant respiratory syncytial virus vaccine in mice

Oil-in-water nano-emulsion adjuvant (NEA) has been utilized for many years in the development of subunit or/and recombinant vaccines. Nevertheless, worries have been expressed about the safety and potential biological activities of the emulsifier. Herein, tocopheryl polyethylene glycol 1000 succinate (TPGS), which acts not only as an emulsifier but also as an immunostimulant, was used for the preparation of NEA. Benefiting from the hydrophilic-hydrophobic nature of TPGS, NEA possess a homogeneous structure with an extremely narrow size distribution (approximately 160 nm in diameter, polydispersity index <0.15), and exhibits excellent stability over 6 months under test conditions. When such an NEA was used with a recombinant respiratory syncytial virus (RSV) vaccine, the adjuvanted vaccine induced enhanced humoral and cellular immunity in mice compared to the non-adjuvanted vaccine. This is the initial documented finding of TPGS adjuvanticity in an intramuscularly injected vaccine. Furthermore, the TPGS-based NEA showed elevated adjuvant potency compared to the MF59-like emulsion adjuvant assessed. These results imply the potential of NEA as an alternative adjuvant for developing recombinant vaccines with enhanced immunity.

Nanogel particles formed from ethanol-treated whey proteins: Effect of heating, pH and NaCl on their stability.

Whey protein particles have gained significant attention for their ability to enhance the functional properties of foods as they can be used for emulsions and foams stabilization or fat substitution. This study explores the ability of whey protein nanogel particles formed in the presence of ethanol (30–70 % w/w) by controlling pH and ionic strength, to retain their morphological properties after ethanol removal. The stability of the produced nanogel particles after the removal of ethanol was investigated under various conditions, including heat treatment (90 °C, 20 min), pH modification (4−7), and the addition of NaCl (50–300 mM). Morphological analysis was conducted using confocal laser scanning microscopy, laser diffraction analysis, and scanning electron microscopy. The results showed that the exclusion of ethanol resulted in the formation of spherical-like nanogel particles with different sizes ranging from 100 to 200 nm in diameter. The pH of the solution affected the stability of the ethanol-free particles, leading to aggregation when the net charge of the protein approached zero. However, no aggregation phenomena were observed away from the isoelectric point. High concentrations of NaCl led to extensive aggregation, but no substantial changes were found upon heating. The production of nanogel particles is a promising advance with potential for a wide range of food applications.