Nanoparticles Of Different Sizes Research Articles

The effects of co-exposures of Zea mays plant to the photon-upconversion nanoparticles; does the size or composition play an important role?

This work thoroughly describes how three different types of photon-upconversion nanoparticles (UCNPs) that differ in size or composition influence a model plant Zea mays. This plant was treated with an aqueous dispersion of nanoparticles in a hydroponic short-term toxicity test (168 h) in three different concentrations (0.5, 5, and 25 μg/mL of yttrium). The plants were exposed in a single toxicity test as well as in so-called co-exposures where the plants were in direct contact with the nanoparticles of different sizes (hydrodynamic diameter 25.9 nm and 58.2 nm) or with different compositions (doped with gadolinium and thulium or with erbium ions) at the same time. After the exposure, basic macroscopic toxicity end-points were monitored. The translocation of nanoparticles across the whole plant was evaluated by Laser-Induced Breakdown Spectroscopy (lateral resolution of 26 and 100 μm) and by photon-upconversion microscanning (lateral resolution of 40 μm). Also, the total content of elements contained in plants was measured for the underground (root and coleoptile) and above-ground (primary leaf) parts separately using Inductively-Coupled Plasma Optical Emission Spectroscopy. Afterwards, bioaccumulation and translocation factors were evaluated. Our results indicated significant toxicity of all tested exposures groups for Z. mays plant. The main bioaccumulation site was the underground part, whereas the transfer to the above-ground part was minimal. Also, the UCNPs showed a low stability and led to a notable release of ions.

Cytocompatibility of oleic acid modified iron oxide nanoparticles

Our long-term goal is to utilize oleic acid-modified iron oxide (OA-Fe3O4) nanoparticles embedded into a monoglyceride matrix for remote drug release utilizing an alternating magnetic field (AMF). However, the toxicological behavior of OA-Fe3O4 nanoparticles when in contact with biological tissues remains unknown. The size, shape, and surface morphology of OA-Fe3O4 nanoparticles prepared in our laboratory were evaluated using SEM and TEM. These data show that the OA-Fe3O4 nanoparticle preparations do not form aggregates and maintain the expected size and shape. We also used HTB-19, a human mammary tumor cell line, to assay the cytocompatibility of OA-Fe3O4 nanoparticles of different sizes (5, 10, 20, and 30 nm) at varying doses (6.25, 12.5, 25, and 50 µg/mL) using CytoTox-Glo™ cytotoxicity kit and phase-contrast inverted microscopy. These results indicate that there is no appreciable cytotoxicity at the lowest (6.25 µg/mL) concentration. Even the highest (50 µg/mL) concentration used in our study show > 75% cell viability. Microscopic morphological assessment performed using phase-contrast inverted microscopy revealed internalization of the nanoparticles and proliferation of cells in the presence of the OA-Fe3O4 nanoparticles. Taken together, our results show that OA-Fe3O4 nanoparticles are a safe and promising biocompatible excipient for drug delivery.

Magnetic Relaxation Switch Sensor Based on Magnetophoresis and "T-Hg(II)-T" Signal Amplification.

In this study, we designed a magnetic relaxation switch (MRS) sensor combined with magnetophoresis technology (MS-MRS), which helps solve the problems of traditional MRS sensors. The sensor is based on a new combined magnet and is composed of small magnetic blocks and iron sheets that can rapidly separate magnetic nanoparticles of different sizes within 5 min. The MS-MRS sensor consists of aptamer-functionalized magnetic nanoparticles (diameter: 200 nm) (MNP200-Apt), complementary DNA-functionalized magnetic nanoparticles (diameter: 20 nm) (MNP20-cDNA), and a combined magnet ("M2" magnet). The MNP200-Apt probe could be separated by an "M2" magnet but the MNP20-cDNA probe could not. To further improve the sensitivity of the sensor, we successfully constructed an MS-MRS-Hg sensor based on the "T-Hg(II)-T" specific recognition that aggregated MNP20-cDNA probes to amplify the relaxation signal. The detection working range of the MS-MRS sensor is 0.5-100 ng/mL and that of the MS-MRS-Hg sensor is 0.05-100 ng/mL. Their limit of detection (LOD) values are 0.15 and 0.01 ng/mL, respectively. The relative recoveries of the MS-MRS and MS-MRS-Hg sensors are 95.2-119.5% and 93.1-113.1%, respectively. These results indicate that the proposed sensors have a high accuracy level.

Size- and Ligand-Dependent Transport of Nanoparticles in Matricaria chamomilla as Demonstrated by Mass Spectroscopy and X-ray Fluorescence Imaging.

Matricaria chamomilla flowers were incubated with gold nanoparticles of different sizes ranging from 1.4 to 94 nm. After different incubation times of 6, 12, 24, and 48 h, the gold distribution in the flowers was destructively measured by inductively coupled plasma mass spectrometry (ICP-MS) and non-destructively measured by X-ray fluorescence imaging (XFI) with high lateral resolution. As a control, the biodistribution of iodine ions or iodine-containing organic molecules (iohexol) was determined, in order to demonstrate the feasibility of mapping the distribution of several elements in parallel. The results show a clear size-dependent transport of the nanoparticles. In addition, the surface chemistry also plays a decisive role in disposition. Only the 1.6 nm nanoparticles coated with acetylcysteine could be efficiently transported through the stem of the flowers into the petals. In this case, almost 80% of the nanoparticles which were found within each flower were located in the petals. The study also highlights the potential of XFI for in situ recording of in vivo analyte biodistribution.

Multidrug-Resistant Bacterial Pathogens and Public Health: The Antimicrobial Effect of Cyanobacterial-Biosynthesized Silver Nanoparticles.

Background: Cyanobacteria are considered as green nano-factories. Manipulation of the size of biogenic silver nanoparticles is needed to produce particles that suit the different applications such as the use as antibacterial agents. The present study attempts to manipulate the size of biosynthesized silver nanoparticles produced by cyanobacteria and to test the different-sized nanoparticles against pathogenic clinical bacteria. Methods: Cyanothece-like. coccoid unicellular cyanobacterium was tested for its ability to biosynthesize nanosilver particles of different sizes. A stock solution of silver nitrate was prepared from which three different concentrations were added to cyanobacterial culture. UV-visible spectroscopy and FTIR were conducted to characterize the silver nanoparticles produced in the cell free filtrate. Dynamic Light Scattering (DLS) was performed to determine the size of the nanoparticles produced at each concentration. The antimicrobial bioassays were conducted on broad host methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus sp., was conducted to detect the nanoparticle size that was most efficient as an antimicrobial agent. Results. The UV-Visible spectra showed excellent congruence of the plasmon peak characteristic of nanosilver at 450 nm for all three different concentrations, varying peak heights were recorded according to the concentration used. The FTIR of the three solutions revealed the absence of characteristic functional groups in the solution. All three concentrations showed spectra at 1636 and 2050–2290 nm indicating uniformity of composition. Moreover, DLS analysis revealed that the silver nanoparticles produced with lowest concentration of precursor AgNO3 had smallest size followed by those resulting from the higher precursor concentration. The nanoparticles resulting from highest concentration of precursor AgNO3 were the biggest in size and tending to agglomerate when their size was above 100 nm. The three types of differently-sized silver nanoparticles were used against two bacterial pathogenic strains with broad host range; MRSA-(Methicillin-resistant Staphylococcus aureus) and Streptococcus sp. The three types of nanoparticles showed antimicrobial effects with the smallest nanoparticles being the most efficient in inhibiting bacterial growth. Discussion: Nanosilver particles biosynthesized by Cyanothece-like cyanobacterium can serve as antibacterial agent against pathogens including multi-drug resistant strains. The most appropriate nanoparticle size for efficient antimicrobial activity had to be identified. Hence, size-manipulation experiment was conducted to find the most effective size of nanosilver particles. This size manipulation was achieved by controlling the amount of starting precursor. Excessive precursor material resulted in the agglomeration of the silver nanoparticles to a size greater than 100 nm. Thereby decreasing their ability to penetrate into the inner vicinity of microbial cells and consequently decreasing their antibacterial potency. Conclusion: Antibacterial nanosilver particles can be biosynthesized and their size manipulated by green synthesis. The use of biogenic nanosilver particles as small as possible is recommended to obtain effective antibacterial agents.

Taking advantage of large water-unstable Zn4O(BDC)3 nanoparticles for fabricating the PMM-based TFC FO membrane with improved water flux in desalination process

Developing the forward osmosis (FO) membranes to enhance their efficiency is of great importance as this technology is an important option to overcome water scarcity. In the present study, the water-unstable Zn4O(BDC)3 (where BDC = 1,4-benzodicarboxylate) nanoparticles of different sizes were embedded into the polyethersulfone (PES) matrix to form the porous-matrix membranes (PMMs) as the support layers in the forward osmosis FO thin-film composite (TFC) membranes. The main idea of this approach is to suppress the negative effect of the dilutive internal concentration polarization (DICP) in the FO mode by increasing the mean pore size and porosity of the support layer of the TFC FO membranes, leading to an enhanced FO water flux. According to the results, the water flux (Jw) increased from 26 L/m2.h in the pristine membrane (TFC-C) to 34 L/m2.h in the TFC-MOF-2 membrane fabricated with the large size Zn4O(BDC)3 nanoparticles (108 nm particle size and 2 wt. % loadings). Also, this membrane was used for the Caspian seawater desalination, and the water flux of 28.10 L/m2h (18.72 for the TFC-C) and the water flux reduction of 6 % (18.48 % for the TFC-C) during the long-term experiment were obtained.

Controlling size, shape, and charge of nanoparticles via low-energy miniemulsion and heterogeneous RAFT polymerization

Size, shape, and charge are key parameters of nanoparticles, and variations in these parameters can significantly impact their properties and applications. Among various nanoparticle synthesis methods, the combination of low-energy miniemulsions with reversible addition-fragmentation chain-transfer (RAFT) polymerization allows for the facile, rapid, and environmentally friendly preparation of uniform nanoparticles. However, this method cannot, yet, simultaneously control the size, shape, and charge of nanoparticles, thereby limiting its potential applications. Here we report the synthesis of polymeric nanoparticles with concurrent control over particle size, shape, and charge via low-energy miniemulsion and heterogeneous RAFT polymerization. Key to our approach is the combination of (i) a macromolecular surface-active agent to facilitate the formation of nanodroplets, (ii) various small-molecule surfactants with different charges to control the size and charge of nanodroplets, and (iii) a molecular transformer to control the morphology of the final polymeric nanoparticles. In particular, negatively charged polystyrene nanoparticles of different sizes (from ∼100 to ∼500 nm) and shapes (sphere, worm, and vesicle) were obtained by simply tuning the amount of added sodium dodecyl sulfate (SDS) and toluene. The nanoparticle charge was then switched from negative to positive by replacing SDS with cetyltrimethylammonium bromide (CTAB), a positively charged surfactant. In addition, biocompatible and neutral surfactants (including Tweens and Span 80) were employed to tune the nanoparticle size yielding challenging-to-synthesize nanoworms. This work provides a simple but powerful approach to produce nanoparticles of different properties, thus expanding the scope of nanomaterials made by RAFT low-energy miniemulsion polymerization.

The evaluation of anticancer activity by synthesizing 5FU loaded albumin nanoparticles by exposure to UV light

In this study, as a new synthesis method, UV light was employed as a type of cross-linking agent to control drug storage and to produce nanoparticles of different sizes and to stabilize the nanoparticles for the first time. We showed that the exposure time of the 5FU albumin solution to UV light produces differences in the size and characterization of the nanoparticles and also produces different cytotoxic effects on MCF-7 breast cancer cells. While the 5FU-A1 nanoparticles we synthesized with 1 h UV storage were approximately 43 nm, the 5FU-A2 nanoparticles we synthesized with UV storage for 3 h increased to an average of 300 nm. 5FU-A1 (IC50 value: 2.5 μg/mL) was approximately 16 times more cytotoxic than free 5FU (IC50 value 39.39 μg/mL) on MCF-7 cancer cells. Moreover, when normal HUVEC cells are treated with 5FU-A1 at a concentration of 2.5 μg/mL, more than 80% of these normal cells remain viable. In addition, we examined the rate of early-to-late apoptosis and necrosis in MCF-7 cancer cells using the Annexin V/PI flow cytometry assay. According to our results, 5FU-A1 promoted the apoptosis pathway. Finally, we examined P-gp activity with MDR1/ABCB1 antibody by flow cytometry and Rhodamine123 with fluorescent dye.

Reinforcement Effects of Inorganic Nanoparticles for PAM‐g‐carboxymethyl Xylan Nanocomposite Hydrogels

AbstractA variety of 0D nanoparticles (MgO, ZnO, Al2O3, Fe2O3, SiO2, and TiO2) as nanofiller materials are introduced into polyacrylamide‐g‐carboxymethyl xylan (PAM‐g‐CMX) composite hydrogel. The effects of different shapes and different sizes of nanoparticles on the properties of hydrogels are investigated. The properties of nanocomposite hydrogels are analyzed by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy (SEM), rheological analysis, swelling analysis, and mechanical test. Composite hydrogels with nanoparticles exhibit uniform pore structure and smaller pore size in SEM images, resulting in a reduced equilibrium swelling ratio. In addition, the results show that the hydroxyl groups on the surface of the nanoparticles forms hydrogen bonds with the amino groups and carboxyl groups in the PAM‐g‐CMX cross‐linked network which improve the mechanical strength of nanocomposite hydrogels. The hydrogel with 20 nm MgO has the maximum compressive strength (550.9 kPa), tensile strength (28.6 kPa), and the longest elongation (813%) owing to the spherical shape and small size of MnO (20 nm). The hydrogels with nanoparticles maintain the originated 90% strength after 30 cycles of compressive test. The hydrogels with nanoparticles will offer new insights for xylan application.

Development and Evaluation from Laboratory to Field Trial of a Dual-Purpose Fracturing Nanofluid: Inhibition of Associated Formation Damage and Increasing Heavy Crude Oil Mobility.

This study aims to develop and evaluate fracturing nanofluids from the laboratory to the field trial with the dual purpose of increasing heavy crude oil mobility and reducing formation damage caused by the remaining fracturing fluid (FF). Two fumed silica nanoparticles of different sizes, and alumina nanoparticles were modified on the surface through basic and acidic treatments. The nanoparticles were characterized by transmission electron microscopy, dynamic light scattering, zeta potential and total acidity. The rheological behavior of the linear gel and the heavy crude oil after adding different chemical nature nanoparticles were measured at two concentrations of 100 and 1000 mg/L. Also, the contact angle assessed the alteration of the rock wettability. The nanoparticle with better performance was the raw fumed silica of 7 nm at 1000 mg/L. These were employed to prepare a fracturing nanofluid from a commercial FF. Both fluids were evaluated through their rheological behavior as a function of time at high pressure following the API RP39 test, and spontaneous imbibition tests were carried out to assess the FF’s capacity to modify the wettability of the porous media. It was possible to conclude that the inclusion of 7 nm commercial silica nanoparticles allowed obtaining a reduction of 10 and 20% in the two breakers used in the commercial fracture fluid formulation without altering the rheological properties of the system. Displacement tests were also performed on proppant and rock samples at reservoir conditions of overburden and pore pressures of 3200 and 1200 psi, respectively, while the temperature was set at 77 °C and the flow rate at 0.3 cm3/min. According to the effective oil permeability, a decrease of 31% in the damage was obtained. Based on these results, the fracturing nanofluid was selected and used in the first worldwide field application in a Colombian oil field with a basic sediment and water (BSW%) of 100 and without oil production. After two weeks of the hydraulic fracture operation, crude oil was produced. Finally, one year after this work, crude oil viscosity and BSW% kept showing reductions near 75% and 33%, respectively; and having passed two years, the cumulative incremental oil production is around 120,000 barrels.

Probing the structure sensitivity of dimethyl oxalate partial hydrogenation over Ag nanoparticles: A combined experimental and microkinetic study

Silver nanoparticles of different sizes have been synthesized to study their catalytic performance in dimethyl oxalate (DMO) partial hydrogenation to methyl glycolate (MG). Then, a detailed microkinetic analysis based on the results of DFT calculations has been performed to elucidate the origin of the observed size-dependent kinetics, where tabulated thermodynamic properties of gas-phase species are used to ensure the thermodynamic consistency of the reaction. Calculated results show that the turnover frequency for DMO consumption is much higher on Ag(211) than on Ag(111), suggesting the stepped surface dominates the kinetics. The hydrogenation of DMO on the two surfaces occurs along the same dominant reaction pathway, and the rate-determining step for the partial and deep hydrogenation of DMO is DMO and MG dissociation, respectively. The finding that the MG selectivity increases while the DMO hydrogenation activity decreases with the Ag nanoparticle size reveals the structure sensitivity of DMO partial hydrogenation.

SnO2 nanoparticles with different aspect ratio and structural parameters: fabrication, photocatalytic efficiency dependences and fast organic dyes degradation

A synthetic approach to obtain nanoparticles of different sizes and shapes via hydrothermal treatment was developed. It was shown that hydrothermal treatment engage oriented attachment mechanism of nanoparticle formation. Obtained nanoparticles were filly characterized by a wide set of methods, their structural parameters were studied and correlations of later with the synthesis procedure were shown. A series of nanoparticles of various sizes and shapes were tested as photocatalysts for cyclic organic pollutants. Fast photodegradation (100% within 10 min) of methylene blue and rhodamine 6G under UV light was achieved. Degradation mechanism was studied, taking into account adsorption stage, pollutant-nanoparticle surface interactions and vacancies to defects ratio, involving computer calculations. A key factor affecting photocatalytic efficiency was revealed.

High-pressure neutron diffraction study of magnetite, Fe3O4, nanoparticles

We use in situ high-pressure neutron powder diffraction to study elastic properties of Fe3O4 magnetite nanoparticles of different sizes. It is found that nanoparticles are elastically softer than the bulk. Apart from the smallest nanoparticle of diameter 8 nm, the atomic and magnetic structures do not change significantly with nanoparticle size or pressure. The 8 nm sample appears to take a disordered spinel structure instead of the inverse spinel structure of the bulk and larger nanoparticles, as seen in bond lengths and magnetic structures. Synchrotron x-ray total scattering was used to support this interpretation. Furthermore, this study suggests that the influence of magnetic disorder at the nanoparticle surface is significant for the size of 8 nm.

Effects of Methoxyfenozide-Loaded Fluorescent Mesoporous Silica Nanoparticles on Plutella xylostella (L.) (Lepidoptera: Plutellidae) Mortality and Detoxification Enzyme Levels Activities.

The diamond back moth, Plutella xylostella, causes severe damage at all crop stages, beside its rising resistance to all insecticides. The objective of this study was to look for a new control strategy such as application of insecticide-loaded carbon dot-embedded fluorescent mesoporous silica nanoparticles (FL-SiO2 NPs). Two different-sized methoxyfenozide-loaded nanoparticles (Me@FL-SiO2 NPs-70 nm, Me@FL-SiO2 NPs-150 nm) were prepared, with loading content 15% and 16%. Methoxyfenozide was released constantly from Me@FL-SiO2 NPs only at specific optimum pH 7.5. The release of methoxyfenozide from Me@FL-SiO2 NPs was not observed other than this optimum pH, and therefore, we checked and controlled a single release condition to look out for the different particle sizes of insecticide-loaded NPs. This pH-responsive release pattern can find potential application in sustainable plant protection. Moreover, the lethal concentration of the LC50 value was 24 mg/L for methoxyfenozide (TC), 14 mg/L for Me@FL-SiO2 NPs-70 nm, and 15 mg/L for Me@FL-SiO2 NPs-150 nm after 72 h exposure, respectively. After calculating the LC50, the results predicted that Me@FL-SiO2 NPs-70 nm and Me@FL-SiO2 NPs-150 nm exhibited better insecticidal activity against P. xylostella than methoxyfenozide under the same concentrations of active ingredient applied. Moreover, the activities of detoxification enzymes of P. xylostella were suppressed by treatment with insecticide-loaded NPs, which showed that NPs could also be involved in reduction of enzymes. Furthermore, the entering of FL-SiO2 NPs into the midgut of P. xylostella was confirmed by confocal laser scanning microscope (CLSM). For comparison, P. xylostella under treatment with water as control was also observed under CLSM. The control exhibited no fluorescent signal, while the larvae treated with FL-SiO2 NPs showed strong fluorescence under a laser excitation wavelength of 448 nm. The reduced enzyme activities as well as higher cuticular penetration in insects indicate that the nano-based delivery system of insecticide could be potentially applied in insecticide resistance management.

Nanoprojectile Secondary Ion Mass Spectrometry for Nanometrology of Nanoparticles and Their Interfaces.

Nanoscale molecular characterization plays a crucial role in enhancing our insights into fundamental and materials processes occurring at the nanoscale. However, for many traditional techniques, measurements on different ensembles are mixed and the analytical result reflects the average surface composition or arrangement. Advances in nanometrologies that allow for measurements to be differentiated based on the chemical environment examined are critical for accurate analysis. Here, we present a variant of secondary ion mass spectrometry, SIMS, termed nanoprojectile SIMS, NP-SIMS, capable of nanoscale molecular analysis. The technique examines the sample with a suite, 106-107, of individual gold nanoprojectiles (e.g., Au4004+) which stochastically probe the surface. Analysis of coemitted ions from each impact allows for the inspection of colocalized moieties within the ejected volume of a single projectile impact (10-15 nm in diameter). If some of these 106-107 measurements arise from nanodomains of similar composition, data can be grouped based on the detected secondary ions. We applied the method to examine a mixture of three different-sized nanoparticles with identical metal cores (3-5 nm in diameter), differing in the length of the attached ligand (decanetiol, tetradecanethiol, and hexadecanethiol). Using NP-SIMS, we determined the relative abundance of the three particles on the surface and isolated measurements based on the impact parameter between the impacting nanoprojectile and the surface particle, demonstrating that measurements occurring near the center of the particle can be differentiated from those at the particle-particle and particle-substrate interfaces. The results suggest that the described methodology is well-suited for molecular analysis of nanoassemblies and may be applied for tracking defects. Here we demonstrate that, using NP-SIMS, ensemble averaging can be avoided and molecular analysis can be undertaken at a scale below 5 nm, allowing for nanoscale molecular analysis of nano-objects and their interfaces.

Structural, optical and radiation shielding properties of ZnS nanoparticles QDs

In this paper, the structural, optical and radiation shielding properties of ZnS nanoparticles (NPs) Quantum Dots (QDs) were studied by changing the molarity of the sulfur source used for the synthesis. The molarity change method of the sulfur source is suitable for the fabrication of ZnS nanoparticles of different sizes. X-ray diffraction (XRD), transition electron microscopy (TEM), Fourier transform infrared spectrophotometer (FTIR), Photoluminescence (PL) and UV–visible spectroscopy were used to study the structure and optical properties of ZnS QDs. XRD analyses exhibit cubic structure with the average crystallite size in the range (3.8–2 nm). The spherical shape is observed from TEM images. Analyses of FTIR and PL emission peaks, with different molarity of the sulfur source, confirmed the structural deformation resulting from the different concentrations of S. The analyses of absorption spectra measured by UV–visible spectroscopy indicated a strong quantum confinement effect for the ZnS samples prepared with different molarity of S source. The linear attenuation coefficient (LAC), half-value layer (HVL), tenth value layer (TVL) and the mean free path (MFP) at the photon energy from 0.015 to 15 MeV, were evaluated using Phy-X / PSD software program. It is found that the LAC increases with increasing nanoparticle size, while HVL, TVL and MFP decrease as the particle size decreases. Moreover, the fast neutron removal cross-section ƩR has been evaluated.

Structural view of insulin adsorption on the multiple sizes of Cu nanoparticles; molecular dynamics simulation study

Copper nanoparticles with different sizes cause significant changes in humans, and their interaction with biological molecules such as proteins is one of molecular biology's most critical and difficult challenges. One of the valuable tools for understating the mechanisms of different protein-nanoparticle interactions are molecular dynamics simulations. The present work attempts to understand how insulin interaction mechanisms Cu nanoparticles of different sizes (2, 6, and 10 nm) may occur with the molecular dynamics simulations methods. According to the results, in comparison to 2 and 6 nm nanoparticles, insulin interaction with the Cu 10 nm nanoparticle surface exhibits higher relative stability. The Van der Waals Forces (VDW) interactions show that by increasing the nanoparticle size from 2 nm to 6 nm (−673.32 and −847.83Kj/mol, respectively), the VDW energy leads to a significant increase. Although in the CU 10 nm, a noticeable decrease in VDW energy interaction was demonstrated (−357.21Kj/mol) due to present of three disulfide bond which act as a node that limits the excessive opening of insulin and another reason is the decline of surface electron density with increasing Cu-NP size. The secondary structure changes of insulin in the interaction with different sizes of Cu nanoparticles show the B-chain of insulin in the 2 and 6 nm nanoparticles systems had an essential role in the formation of interaction energy, in return for Cu 10 nm nanoparticle with the lowest energy level the chain-A has the bolder role. In the insulin-Cu 6 nm nanoparticle β-sheet structure formation in the GlnB4, HisB5, LeuB6, GlyB20, GluB21, and ArgB22 residues was observed around 30 ns. Also, in these amino acids, a partial β-sheet formation in B-chain has been apparent in the insulin-Cu 2 nm nanoparticle system. In the presence of the largest Cu nanoparticle in this study, a rise in helix, random coil, and B-bridge in secondary insulin structure was seen. It is considerable that in this system the most significant structural change occurring in the A-chain. The results of the hydrophilic-hydrophobicity properties and solvent accessible surface analyses also indicated that the insulin is unfolded during its interaction with different sizes of Cu nanoparticles.

Simulation and Experimental Study of the Multisized Silver Nanoparticles Sintering Process Based on Molecular Dynamics.

Multisized nanoparticles (MPs) are widely employed as electronic materials to form conductive patterns, benefitting from their excellent sintering properties and mechanical reliability. However, due to the lack of effective detection methods for the real-time sintering process, it is difficult to reveal the sintering behavior during the MPs sintering process. In this work, a molecular dynamics method is used to track the trajectory of silver atoms. The melting behavior of a single nanoparticle (SP) is first discussed. The structural evolution of equally sized nanoparticles (EPs) and unequally sized nanoparticles (UPs) during the sintering process is analyzed alongside morphology changes. It is proposed that the UPs sintering process benefits from the wetting behavior of small-sized nanoparticles on the surface of large-sized nanoparticles, and the sintering angle (θ) is proposed as an index to estimate the sintering result of UPs. Based on the works above, three basic sintering modes and one advanced sintering mode in the MP sintering process are analyzed emphatically in this paper, and the roles of different-sized nanoparticles in MPs are concluded from simulation and experimental results. This work provides theoretical support for conductive ink composition design and sintering process optimization.

Development of colorimetric sensors based on gold nanoparticles for SARS-CoV-2 RdRp, E and S genes detection

We present a fast, reliable and easy to scale-up colorimetric sensor based on gold nanoparticles (AuNPs) to detect the sequences coding for the RdRp, E, and S proteins of SARS-CoV-2. The optimization of the system (so-called “the sensor”) includes the evaluation of different sizes of nanoparticles, sequences of oligonucleotides and buffers. It is stable for months without any noticeable decrease in its activity, allowing the detection of SARS-CoV-2 sequences by the naked eye in 15 min. The efficiency and selectivity of detection, in terms of significative colorimetric changes in the solution upon target recognition, are qualitatively (visually) and quantitatively (absorbance measurements) assessed using synthetic samples and samples derived from infected cells and patients. Furthermore, an easy and affordable amplification approach is implemented to increase the system's sensitivity for detecting high and medium viral loads (≥103 - 104 viral RNA copies/μl) in patient samples. The whole process (amplification and detection) takes 2.5 h. Due to the ease of use, stability and minimum equipment requirements, the proposed approach can be a valuable tool for the detection of SARS-CoV-2 at facilities with limited resources.

Interaction of Human Dendritic Cells with Graphene Oxide Nanoparticles In Vitro.

We studied the effect of graphene oxide nanoparticles on the differentiation of human dendritic cells and uptake of nanoparticles by these cells in vitro. The objects of the study were mononuclear cells from healthy donors induced into the phenotype of dendritic cells by cytokines (IL-6 and GM-CSF). We used graphene oxide nanoparticles of different sizes functionalized with linear or branched PEG (P-GO or bP-GO) in concentrations of 5 and 25 μg/ml. It was found that graphene oxide nanoparticles did not affect the viability and percentage of dendritic cells in the culture. However, P-GO nanoparticles (25 μg/ml) suppressed the expression of CD83 on the surface of dendritic cells in cultures, thereby suppressing cell differentiation. Dendritic cells internalized P-GO nanoparticles, particles in high concentration were more actively engulfed, but the size of the particles and the type of PEG did not affect the intensity of this process. In general, P-GO nanoparticles in a concentration of 25 μg/ml can regulate differentiation of dendritic cells by suppressing their maturation.