Surface Modification Of Nanoparticles Research Articles

Cinnamomum verum-derived bioactives-functionalized gold nanoparticles for prevention of obesity through gut microbiota reshaping.

Existing drugs have limited success in managing obesity in human due to their low efficacy and severe side-effects. Surface-modified gold nanoparticles have now received considerable attention of researchers for efficient biomedical applications owing to their superior uptake by cells, biocompatibility, hydrophilicity and non-immunogenicity. Here we prepared Cinnamomum verum derived bioactives-functionalized gold nanoparticles (Au@P-NPs) and assessed their impact on obesity and related immune-metabolic complications in high-fat diet (HFD)-induced obese mice using metabolic experiments along with 16S RNA gene-based gut microbial profiling and faecal microbiota transplantation (FMT). Au@P-NPs treatment prevented weight gain, decreased fat deposition, reduced metabolic inflammation and endotoxaemia in HFD-fed mice. Au@P-NPs-treated group exhibited better glucose tolerance and insulin sensitivity than HFD-fed control mice, and got completely protected against hepatic steatosis. These impacts were related to increased energy expenditure and enhanced Ucp1 expression in the brown adipose tissues of Au@P-NPs-administered animals, which strongly linked with the mRNA expression of the membrane bile acid receptor TGR5. Treatment of HFD-fed animals with Au@P-NPs altered plasma bile acid profile, and increased Akkermansia muciniphila and decreased Lactobacillus populations in the faeces. Au@P-NPs-treated animals revealed altered plasma bile acid profile, and increased Akkermansia muciniphila and decreased Lactobacillus populations in the faeces. FMT experiments showed lesser weight gain and greater energy expenditure in the mice fed with faecal suspension from Au@P-NPs-treated animals than that from HFD-fed mice. These results clearly establish that gold nanoparticles functionalized with bioactive compounds of C. verum have high potential to be an anti-obesity drug.

Insights into the impact of photophysical processes and defect state evolution on the emission properties of surface-modified ZnO nanoplates for application in photocatalysis and hybrid LEDs.

The effects of surface modification on the defect state densities, optical properties, and photocatalytic and quantum efficiencies of zinc oxide (ZnO) nanoplates were studied in this work. The aim of this study is to identify the photophysical processes that dictate the quenching of emission from defect states upon surface modification and the role of different defects such as zinc interstitials (Zni) or oxygen vacancies (VO) beside the photophysical processes in determining the photocatalytic efficiency of plate-like ZnO nanostructures. For controlling the intrinsic defect state densities of ZnO nanoplates, which is difficult to achieve, their surface was modified using different polymers such as PMMA and PVA. X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) emission spectroscopy were employed to identify and quantify the defect states. The analysis of relative defect state densities of Zni or VO showed that Zni significantly impacts the photocatalytic activity (PCA) besides VO, but it has a lower influence than VO because of the difference in the accessibility and intrinsic nature of these two defects. Synchronous quenching of emission from different defect states with different formation energies and its correlation with the photocatalytic activity led us to conclude that photophysical processes such as concentration-dependent Förster resonance energy transfer (FRET), charge transfer (CT) and Zni defects play a significant role behind PCA, which has been previously reported to be influenced by VO only. FRET and CT also play a critical role behind emission quenching upon surface modification. Upon the surface modification of nanoplates, a drop in the quantum efficiency from 12.14% to 4.44% was observed with the fine-tuning of emission colour from bluish-white to blue. Besides the defect states, FRET and CT phenomena are dominant in reducing the quantum efficiency of hybrid light-emitting diodes (HyLEDs) and photocatalytic efficiency. Therefore, the work outlines the reason behind the suppression of luminescence and photocatalytic efficiency of ZnO nanoparticles after surface modification and how to optimise them for their applications as an emissive layer in HyLEDs and efficient photocatalysts.

Study of oleic acid as a surface modifying agent for oxide nanoparticles

The development of nano lubricants has increased rapidly in recent years. With the addition of nano-additives to conventional oils to enhance tribological properties, the stability of nanoparticles remains a challenge, which can be ruled out with the help of surface modification of nanoparticles. So, oxide nanoparticles (Al2O3, CuO, and SiO2) are analyzed in this study. The morphology of the nanoparticles is analyzed with the aid of a high-resolution field-emission scanning-electron microscope (HR FESEM) and found to be nearly spherical. The surface modification process is done with the help of oleic acid (OA). The surface modification process parameters are thoroughly discussed. The Fourier transform infrared spectroscopy (FTIR) result shows prominent oleic acid capping on oxide nanoparticles.

Thermal properties of surface-modified nano-Al2O3/Kevlar fiber/epoxy composites

The mechanical and thermal properties of Kevlar fiber reinforced polymer composites are favorable. Researchers have extensively studied to improve these composites' mechanical characteristics, but research into improving their thermal properties is still limited. The aim of this study is to further improve the thermal properties of Kevlar fiber reinforced epoxy composite using surface modified Al2O3 nanoparticles. Vacuum-assisted resin infusion method (VARIM) was used to produce nanocomposite laminates. The surface of Al2O3 nanoparticles was modified with a silane coupling agent. Ultrasonication and magnetic mixing were used to incorporate Al2O3 at various wt.% (1, 2, 3, 4 and 5) into epoxy. Thermal stability was determined by performing differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA) and measuring thermal conductivity and thermal diffusivity. The results obtained revealed that the surface-modified Al2O3 nanoparticles exhibit good thermal barrier properties and improve thermal stability. In terms of degradation temperature and specific heat capacity, the thermal stability of Kevlar composites is best at 3 wt% Al2O3. SEM images and EDX processing were used to determine the morphological characteristics. The chemical composition was confirmed by EDX analysis, and SEM images revealed that the failure occurred in fiber and matrix-related mechanisms. Fourier transform infrared (FT-IR) spectra were recorded using a FT-IR spectrophotometer. It was seen that three new peaks appear with the addition of surface-modified Al2O3.

Cross-Linked Enzyme-Adhered Nanoparticles (CLEANs) for Continuous-Flow Bioproduction.

Nanostructured but micro-sized biocatalysts were created by bottom-up technology using multi-functionalized silica nanoparticles (NPs) as nano-sized building blocks to form cross-linked enzyme-adhered nanoparticles (CLEANs) as robust micro-sized particles with beneficial internal structure and good mechanical properties. Systematic surface modification of NPs with a grafting mixture consisting of organosilanes with reactive (aminopropyl) and inert (e. g., vinyl, propyl, phenyl, or octyl) functions resulted in functional NPs enabling cross-linking agents, such as glutardialdehyde or bisepoxides (glycerol diglycidyl ether, neopentylglycol diglycidyl ether, and poly(propylene glycol) diglycidyl ether), to bind and cross-link enzymes covalently and to form macroporous microparticles. These CLEANs were able to diminish several weaknesses of traditional cross-linked enzyme aggregates as biocatalysts, such as poor mechanical resistance, difficult recovery, and storage, strengthening their use for packed-bed enzyme reactors. Lipase B from Candida antarctica (CaLB) was selected as model enzyme for development of robust CLEANs, which were successfully tested for various industrially relevant applications including a kinetic resolution of a racemic alcohol and the production of various natural fragrance compounds under continuous-flow conditions.

Immunological Assessment of Chitosan or Trimethyl Chitosan-Coated PLGA Nanospheres Containing Fusion Antigen as the Novel Vaccine Candidates Against Tuberculosis.

The crucial challenge in tuberculosis (TB) as a chronic infectious disease is to present a novel vaccine candidate that improves current vaccination and provides efficient protection in individuals. The present study aimed to evaluate the immune efficacy of multi-subunit vaccines containing chitosan (CHT)- or trimethyl chitosan (TMC)-coated PLGA nanospheres to stimulate cell-mediated and mucosal responses against Mycobacterium Tuberculosis (Mtb) in an animal model. The surface-modified PLGA nanoparticles (NPs) containing tri-fusion protein from three Mtb antigens were produced by the double emulsion technique. The subcutaneously or nasally administered PLGA vaccines in the absence or presence of BCG were assessed to compare the levels of mucosal IgA, IgG1, and IgG2a production as well as secretion of IFN-γ, IL-17, IL-4, and TGF-β cytokines. According to the release profile, the tri-fusion encapsulated in modified PLGA NPs demonstrated a biphasic release profile including initial burst release on the first day and sustained release within 18days. All designed PLGA vaccines induced a shift of Th1/Th2 balance toward Th1-dominant response. Although immunized mice through subcutaneous injection elicited higher cell-mediated responses relative to the nasal vaccination, the intranasally administered groups stimulated robust mucosal IgA immunity. The modified PLGA NPs using TMC cationic polymer were more efficient to elevate Th1 and mucosal responses in comparison with the CHT-coated PLGA nanospheres. Our findings highlighted that the tri-fusion loaded in TMC-PLGA NPs may represent an efficient prophylactic vaccine and can be considered as a novel candidate against TB.

Mixed matrix membranes with highly dispersed MOF nanoparticles for improved gas separation

• IPD is used to modify ZIF-8 nanoparticles by a simple coordination interaction. • IPD@ZIF-8 nanoparticles exhibit excellent dispersity in various solvents. • H 2 /CH 4 selectivity of PI/IPD@ZIF-8 MMM with 45 wt% loading is increased by 46.6%. • The CO 2 plasticization resistance of PI/IPD@ZIF-8 MMMs is improved from 21 to 30 bar. Metal organic frameworks (MOFs) are ideal fillers for preparing mixed matrix membranes (MMMs) because of their molecular sieving property. However, MOF nanoparticles are not easy to be dispersed, which limits their application in MMMs with high MOFs loading. In this study, highly dispersed ZIF-8 nanoparticles with diameter of around 50 nm were prepared by coating isophthalic dihydrazide (IPD) molecular layer onto their surfaces via coordination interaction (abbre. IPD@ZIF-8). Benefiting from the highly stable and highly dispersed IPD@ZIF-8 solution, MMMs with high nanoparticles loading content and excellent uniformity are achieved. The modification of IPD on the surface of ZIF-8 nanoparticles greatly enhances the interfacial affinity between ZIF-8 as filler and 6FDA-Durene polyimide (PI) as polymer matrix under the interaction of strong hydrogen bond between them. Gas permeation results reveal that the H 2 permeability of IPD@ZIF-8 mixed PI (PI/IPD@ZIF-8) MMM with 45 wt% loading content is up to 8000 Barrer and the corresponding ideal selectivities of H 2 /CH 4 and H 2 /N 2 gas pairs are 15.1 and 13.0, which increase by 46.6% and 32.7%, respectively, comparing to those of ZIF-8 mixed PI (PI/ZIF-8) MMMs. The comprehensive separation performance of PI/IPD@ZIF-8 MMMs surpasses the 2008 Robeson’s upper bounds. The surface modification of IPD enhances the CO 2 plasticization resistance property of PI/IPD@ZIF-8 MMMs from 21 bar to 30 bar. This study provides a facile and easy-operated strategy for the surface modification of MOF nanoparticles, and opens up a new way for the preparation of MMMs with high filler loading and good quality.

Improving Thermal Stability and Hydrophobicity of Rutile-TiO2 Nanoparticles for Oil-Impregnated Paper Application

Thermal stress and moisture absorption can cause a synergetic negative impact on kraft paper. Among various approaches for improving the dielectric properties of kraft paper, nanotechnology has had promising results. However, the hydrophilicity of most metal oxide nanoparticles renders nanomodified kraft paper more vulnerable to thermal stress and moisture, thereby inducing degradation. In nanomodified kraft paper research, the use of TiO2 nanoparticles has yielded the most promising results. The major shortfall, however, is the hydrophilicity of TiO2. This work investigated surface modifications of rutile-TiO2 nanoparticles (NPs) for improved hydrophobicity and thermal stability. Rutile-TiO2 NPs is a nontoxic metal oxide that can withstand high temperature and is stable in chemical reactions. Two cases of surfactants were used—alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA). The intention was to increase heat resistance and reduce the surface free energy of the rutile-TiO2 NPs. The impacts of the surface modifiers on the rutile-TiO2 NPs were characterised using FT-IR, muffle furnace, analytical weight balance, and TGA. It was discovered that new functional groups were formed on the modified NPs examined through FT-IR spectra. This indicates new chemical bonds, introduced through the surface modification. The unmodified rutile-TiO2 NPs absorbed moisture, increasing their mass by 3.88%, compared with the modified nanoparticles, which released moisture instead. TGA analysis revealed that AKD- and ASA-modified rutile-TiO2 needed higher temperatures than the unmodified rutile-TiO2 to markedly decompose. AKD, however, gave better performance than ASA in that regard. As an example, those modified with 5% AKD sustained a 45% higher temperature than the pure TiO2 nanoparticles. Furthermore, in both cases of the surfactants, the higher the percent of surfactant content was, the more thermally stable the nanoparticles became. This work demonstrates the possibility of fabricating rutile-TiO2 NPs to give improved hydrophobicity and thermal stability for possible dielectric applications such as in kraft paper for power transformer insulation.

Doxorubicin-conjugated <sup>10</sup>B<sub>4</sub>C nanoparticles: Preparation and application in combined boron neutron capturetherapy/chemotherapy

<p indent=0mm>Boron neutron capture therapy (BNCT), which is capable of killing cancer cells precisely with α particles and recoiling ⁷Li nuclei produced by the nuclear fission reaction of thermal neutrons and ¹⁰B in the cells, has attracted tremendous attentions in recent years. Delivering sufficient ¹⁰B into the cancer cells (> 10⁹/cell) is crucial to successful BNCT. Although considerable effort has been devoted to develop cancer-targeted ¹⁰B delivery agents, currently only two boron-containing compounds, i.e., borylphenylalanine (BPA) and sodium mercaptoundecahydro-closo-dodecaborate (BSH) are clinically used in BNCT. On the other hand, combining BNCT with other cancer treatments such as chemotherapy, photodynamic therapy, and immunotherapy can enhance the therapeutic efficacy. Thus, it is highly desired to develop multifunctional ¹⁰B delivery agents that enable combination cancer therapy. Boron-containing inorganic nanoparticles such as ¹⁰B, ¹⁰B₄C, and ¹⁰BN nanoparticles, containing a large number of boron atoms in a single nanoparticle are promising candidates as ¹⁰B delivery agents for BNCT. In addition, these nanoparticles possess low toxicity and good biocompatibility, and are rich in surface chemistry that facilitates further tailoring. For biomedical applications of inorganic nanoparticles, surface modification is essential to increase their aqueous dispersibility and colloidal stability. We have recently developed polyglycerol (PG) grafting as a convenient and effective method for surface modification of inorganic nanoparticles. The PG layer of hyperbranched topology contains many hydroxyl groups on the periphery, which not only largely increase the hydrophilicity of the nanoparticles, but also provide reactive groups for further functionalization through chemical reactions. Through this approach, a wide range of functional moieties including targeting ligands, fluorescent tags, and therapeutic drugs and DNAs have been immobilized on the surface of nanoparticles. Herein, we developed DOX-conjugated ¹⁰B₄C nanoparticles (¹⁰B₄C-PG-DOX) for combined BNCT/chemotherapy. <sc>¹⁰B₄C</sc> nanoparticles prepared by wet ball milling of ¹⁰B₄C powder possessed many oxygen-containing groups (e.g., B-OH and C-OH) on the surface, which were used as starting points to graft PG through ring-opening polymerization of glycidol. The obtained ¹⁰B₄C-PG was surface engineered to conjugate DOX through pH-sensitive hydrazone bond, yielding ¹⁰B₄C-PG-DOX. The PG layer provides ¹⁰B₄C-PG-DOX with sufficient dispersibility and stability in aqueous media. On the other hand, the conjugated DOX endows the nanoparticles with positive charge and lipophilicity that facilitate cell uptake. When the concentration of ¹⁰B₄C-PG-DOX is <sc>10 μg ¹⁰B/mL</sc>, the number of ¹⁰B atoms in a single treated 4T1 murine breast cancer cell can reach as high as (4.92±0.36)×10¹¹. Following the cell internalization, ¹⁰B₄C-PG-DOX nanoparticles mainly distributed in the lysosomes of 4T1 cells, where the mild acidic environment is capable of cleaving the hydrazone bond to release chemotherapeutic DOX. Upon exposure to thermal neutrons generated by an accelerator, ¹⁰B₄C-PG-DOX exerted excellent therapeutic efficacy of combined BNCT/chemotherapy towards 4T1 cells. In conclusion, multifunctional ¹⁰B₄C-PG-DOX was fabricated by rational surface engineering of ¹⁰B₄C nanoparticles, showing a great promise in combined BNCT/chemotherapy of cancer. Future work will focus on <italic>in vivo</italic> studies of ¹⁰B₄C-PG-DOX, including pharmacokinetics and combination therapy on mouse tumor models.

Mastering Superior Performance Origins of Ionic Polyurethane/Silica Hybrids

Even though reversible interactions within ionic hydrogels are well-studied, underlying mechanisms responsible for the high-value added performance of ionic nanocomposites remain almost unexplored. We herein propose a fundamental understanding aiming at elucidating the mechanism behind the reversible breaking and reformation of ionic bonding in the case of organic–inorganic hybrids made of a combination of imidazolium-functionalized poly(ethylene glycol)-based polyurethane (im-PU) and surface-modified sulfonate silica nanoparticles (SiO2–SO3H). Such ionic hybrids already demonstrated unique features related to the presence of electrostatic interactions, but the underlying mechanisms governing the overall material performance have never been discussed. To dissociate the reinforcement role of nanoparticles and ionic interactions, either standard nonionic SiO2 or ionic SiO2–SO3H nanoparticles were introduced into im-PU. Mechanical performances, thermal transitions, relaxation processes, and the morphology of the hybrids were deeply investigated to better comprehend the mechanisms at the origin of the ionic material reinforcement. In addition, a mechanistic investigation is proposed to quantify the dissipation energy ability of the as-proposed ionic hybrids, and an approach is presented to identify a characteristic time for restoration of reversible ionic bonds under different loading scenarios.

Interactions between TiO2 nanoparticles and plant proteins: Role of hydrogen bonding

Titanium dioxide (TiO2) particles are widely employed in foods and supplements as lightening agents. A substantial fraction of the particles in commercial TiO2 ingredients fall within the nanoscale, i.e., they have diameters below 100 nm. A biocorona can form around TiO2 particles when they are incorporated into food matrices containing plant proteins. In this study, we investigated the molecular interactions between two hydrophobic plant proteins (gliadin and zein) and four types of surface-modified TiO2 nanoparticles (TCN, TCN-1, TCN-2 and TCN-3). Ultraviolet–visible absorption, fluorescence quenching, and Fourier transform infrared spectroscopy indicated that the plant proteins interacted with the surfaces of the TiO2 nanoparticles, resulting in changes in their molecular conformations. Quartz crystal microbalance analysis indicated that the mass of the hard corona increased as the number of hydroxyl groups on the surfaces of the TiO2 nanoparticles increased, which implied that hydrogen bonding played an important role in the formation of the biocorona. These results provide a better understanding of the interactions that may occur in food matrices containing both plant proteins and TiO2 nanoparticles.

Simultaneous improvement of proton conductivity and chemical stability of Nafion membranes via embedment of surface-modified ceria nanoparticles in membrane surface

The lab-synthesized ceria (CeO2) nanoparticles were surface-modified to provide proton conductivity. The dopamine sulfonated ceria (CeO2-DS) nanoparticles were embedded into the thin surface layers of Nafion 212 membranes, resulting in the sandwiched structure. The structure, morphology and properties of the synthesized nanoparticles and membranes were analyzed using a variety of methods including TEM, FTIR, DLS, XRD, XPS, TGA, and SEM-EDS. The CeO2-DS nanoparticles exhibited excellent OH• and OOH• radical scavenging effect for enhanced chemical stability, accompanied by a simultaneous improvement of proton conductivity of the membrane. The proton conductivity of the Nafion-CeO2-DS8 membrane was 0.112 ∼ 0.199 S cm-1 from room temperature to 80 °C, which was about 1.5-fold higher than that of pristine Nafion membrane. Nevertheless, the prepared sandwiched structure membrane demonstrated quite high electrical resistance due to the absence of electrically conductive ceria nanoparticles in the thick middle layer. Consequently, not only the durability but also the cell performance of the membrane was significantly enhanced, illustrating the maximum power density of 522 mW cm-2, which was much higher than those of the pristine and single-layer composite membranes, 460 mW cm-2 and 390 mW cm-2, respectively.

Modification of magnetic nanoparticles surface by oxovanadium(V) complex as a highly efficient heterogeneous nanocatalyst for the green sulfoxidation of sulfides

The present study describes the synthesis of a new nanomagnetic-supported oxovanadium(V) complex with the tridentate Schiff base ligand derived from the condensation reaction between 5-bromosalicylaldehyde and nicotinic acid hydrazide. The supported complex was fully characterized using various physicochemical techniques such as FT-IR, SEM, EDS, TEM, XRD and VSM. Moreover, the obtained heterogeneous nanocatalyst was utilized in the sulfoxidation of the different alkyl and aryl sulfides by using H2O2 in ethanol under reflux conditions. The magnetic nanocatalyst can be recycled magnetically and can be reused several times without a considerable loss of activity.

Photothermocatalytic CO2 Reduction on Magnesium Oxide‐Cluster‐Modified Ni Nanoparticles with High Fuel Production Rate, Large Light‐to‐Fuel Efficiency and Excellent Durability

Highly efficient CO2 reduction to produce fuel driven by solar energy is of great significance to alleviate the greenhouse effect and realize solar energy storage. Herein, a unique nanocomposite of MgO‐cluster‐modified Ni nanoparticles supported on Ni‐doped MgO (MCM–Ni/Ni–MgO) is synthetized by a simple approach. Very high fuel production rate for H2 and CO (78.01 and 88.44 mmol min−1 g−1) as well as a large light‐to‐fuel efficiency (31.7%) are achieved by photothermocatalytic CO2 reduction by CH4 on MCM–Ni/Ni–MgO merely using focused UV–vis–IR illumination. This arises from efficient light‐driven thermocatalysis that is further enhanced by a photoactivation due to the activation energy being considerably reduced upon the illumination. More importantly, it exhibits excellent photothermocatalytic durability due to its extremely low carbon deposition rate of 8.85 × 10−4 gc h−1 g−1 catalyst, reduced by 39.2 times as compared with that of a reference sample of Ni nanoparticles supported on Ni‐doped MgO (Ni/Ni–MgO). The experimental evidences and the functional theory calculations reveal that the surface modification of Ni nanoparticles by MgO cluster not only inhibits the carbon deposition side reactions of CO disproportionation and CH4 complete dissociation, but also significantly accelerates the oxidation of carbon species, thus tremendously decreasing carbon deposition rate.

A surface-modified silicon carbide nanoparticles based electrochemical sensor for free interferences determination of caffeine in tea and coffee

In this work, the surface-modified silicon carbide nanoparticles (SiC-NPs) were used as a sensing material for the determination of caffeine. The [Cu(pydc) (apym)]2 loaded on the surface of functionalized SiC-NPs. The mixture of SiC-NPs/[Cu(pydc)(apym)]2 and graphene nanosheets used as a new electrode material. Cyclic Voltammetry technique used to study the electrochemical behavior of the GC/Gr/SiC-NPs/[Cu(pydc)(apym)]2 modified electrode. The GC/Gr/SiC-NPs/[Cu(pydc)(apym)]2 modified electrode shows excellent electrocatalytic activity toward caffeine oxidation and dramatically reduce the oxidation overpotential. The typical amperometry method is used to evaluate the performance of the sensing material for the determination of caffeine. Under optimum conditions, the detection limit and sensitivity were obtained, 0.313 µM and of 134.1 μA/nM−1, respectively. The performance of the designed sensor was evaluated by the successful determination of caffeine in commercial tea and coffee.

Influence of polyethylene glycol on the physical properties of Co0.2Fe2.8O4 nanoparticles used as MRI contrast agent; synchrotron radiation Fe K-edge XAFS

We have synthesized and characterized the surface-modified nanoparticles (NPs) of Co0.2Fe2.8O4/x polyethylene glycol (PEG) (x = 0, 10, 20, 30, and 40%). The magnetic behavior was correlated with the electronic and structural properties by combining different techniques such as X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), High Resolution Transmission Electron Microscope (HRTEM), X-ray Absorption Fine structure (XAFS) (X-ray Absorption Near Edge Structure (XANES) & Extended X-ray Absorption Fine structure (EXAFS)), and Vibrating Sample Magnetometer (VSM). We have studied the effect of PEG capping with different percent on the structural, electronic, magnetic properties, and relaxivity r2 of the Co0.2Fe2.8O4 NPs. The value of r2 indicates the efficacy of the system as a Magnetic Resonance Imaging (MRI) contrast agent in vitro. XRD showed that the Co0.2Fe2.8O4 is a monophasic spinel structure. XAFS at Fe K-edge gave information about the oxidation state of Fe cations, their fractions, and site distribution, as well as the first and second neighbors' bond lengths. No pronounced changes appeared in XANES and EXAFS results as the main type, ratio, valence, and occupancy of metal ions were similar for all samples. The relationship between the chemical environment of Fe and Co cations and their influence on the physicochemical features of the target NPs, including magnetic performance and surface morphology, was investigated towards selecting the optimum samples for MRI contrast agent application. Although no significant changes in the magnetic properties or the average, morphological, and local/electronic structures, the compositions of 30% and 40% of PEG show promising results for MRI purposes reflecting the role of PEG as a capping agent.

Poly(L-Lactic Acid) Composite with Surface-Modified Magnesium Hydroxide Nanoparticles by Biodegradable Oligomer for Augmented Mechanical and Biological Properties.

Poly(L-lactic acid) (PLLA) has attracted a great deal of attention for its use in biomedical materials such as biodegradable vascular scaffolds due to its high biocompatibility. However, its inherent brittleness and inflammatory responses by acidic by-products of PLLA limit its application in biomedical materials. Magnesium hydroxide (MH) has drawn attention as a potential additive since it has a neutralizing effect. Despite the advantages of MH, the MH can be easily agglomerated, resulting in poor dispersion in the polymer matrix. To overcome this problem, oligo-L-lactide-ε-caprolactone (OLCL) as a flexible character was grafted onto the surface of MH nanoparticles due to its acid-neutralizing effect and was added to the PLLA to obtain PLLA/MH composites. The pH neutralization effect of MH was maintained after surface modification. In an in vitro cell experiment, the PLLA/MH composites including OLCL-grafted MH exhibited lower platelet adhesion, cytotoxicity, and inflammatory responses better than those of the control group. Taken together, these results prove that PLLA/MH composites including OLCL-grafted MH show excellent augmented mechanical and biological properties. This technology can be applied to biomedical materials for vascular devices such as biodegradable vascular scaffolds.

Printable dielectric elastomers of high electromechanical properties based on SEBS ink incorporated with polyphenols modified dielectric particles

In this work, a recently developed 3D additive processing technology termed electrohydrodynamic (EHD) printing was employed to fabricate dielectric elastomer (DE) films by using styrene-ethylene-butylene-styrene (SEBS) inks with the addition of high dielectric titanium dioxide (TiO2) nanoparticles. In order to improve the dispersibility of TiO2 in the SEBS matrix, extracted walnut polyphenols were utilized for surface modification of TiO2 nanoparticles labelled wp-TiO2. The effect of the applied voltage on the ink jet morphology of the obtained SEBS based inks during EHD printing was analyzed. The prepared films had precision patterned shapes and their morphology was studied. It revealed that the dispersibility of TiO2 nanoparticles in the SEBS matrix and their compatibility were greatly improved using this procedure. Furthermore, the printed DE films were found to have excellent mechanical, dielectric and electromechanical properties. For the range of DEs fabricated, the SEBS/10%wp-TiO2 composite exhibited the maximum actuated area strain of 21.5% at an electric field of about 34.0 V/μm without degradation of other properties.

Synthesis, Chemical-Physical Characterization, and Biomedical Applications of Functional Gold Nanoparticles: A Review.

Relevant properties of gold nanoparticles, such as stability and biocompatibility, together with their peculiar optical and electronic behavior, make them excellent candidates for medical and biological applications. This review describes the different approaches to the synthesis, surface modification, and characterization of gold nanoparticles (AuNPs) related to increasing their stability and available features useful for employment as drug delivery systems or in hyperthermia and photothermal therapy. The synthetic methods reported span from the well-known Turkevich synthesis, reduction with NaBH4 with or without citrate, seeding growth, ascorbic acid-based, green synthesis, and Brust–Schiffrin methods. Furthermore, the nanosized functionalization of the AuNP surface brought about the formation of self-assembled monolayers through the employment of polymer coatings as capping agents covalently bonded to the nanoparticles. The most common chemical–physical characterization techniques to determine the size, shape and surface coverage of AuNPs are described underlining the structure–activity correlation in the frame of their applications in the biomedical and biotechnology sectors.

Surface Modification of Magnesium Ferrite Nanoparticles for Selective and Sustainable Remediation of Congo Red

Surface modification of silica-coated magnesium ferrite nanoparticles (MgFe2O4@SiO2 NPs) by 3-aminopropyltriethoxysilane (APTES) shows enhanced selectivity for the removal of Congo Red (CR) from both single and binary aqueous dye solutions. Before coating the surfaces of amine-functionalized magnesium ferrite nanoparticles (MgFe2O4–NH2 NPs) with silica, control studies of the adsorption of cationic, neutral, and anionic dyes were performed using both single and binary dye systems. The studies found that the MgFe2O4–NH2 nanoadsorbent favors the adsorption of indigo carmine (IC) and CR in single dye solutions (>90% removal efficiencies). However, MgFe2O4–NH2 NPs preferentially adsorb CR in binary dye solutions. Interestingly, the selectivity of CR over IC depends on the initial concentration of IC/CR in the IC/CR binary systems. A further enhancement in the selective removal of CR in both single and binary dye solutions was achieved by coating the MgFe2O4–NH2 NPs with silica followed by modification with APTES (i.e., APTES-modified MgFe2O4@SiO2 NPs). The highly selective adsorption capacity for CR on the APTES-modified MgFe2O4@SiO2 nanoadsorbent was attributed to the mixture of polar functional groups (i.e., −OH and −NH2) on the surface of the nanoadsorbent, which facilitates adsorbent–adsorbate interactions such as electrostatic and hydrogen-bonding interactions, which are amplified for CR with its more numerous polar functional groups (i.e., amine, azo, and sulfonate groups). From the results, the APTES-modified MgFe2O4@SiO2 nanoadsorbent offers an effective, inexpensive, and reusable/sustainable system for the selective removal and remediation of Congo Red from wastewaters.