Core-shell Nanoparticles Research Articles

Hierarchical Micro- and Mesoporous Zeolitic Imidazolate Framework-8-Based Enzyme Hybrid for Combination Antimicrobial by Lysozyme and Lactoferrin.

Pathogenic bacteria have consistently posed a formidable challenge to human health, creating the critical need for effective antibacterial solutions. In response, enzyme-metal-organic framework (MOF) composites have emerged as a promising class of antibacterial agents. This study focuses on the development of an enzyme-MOF composite based on HZIF-8, incorporating the advantages of simple synthesis, ZIF-8 antibacterial properties, lysozyme hydrolysis, and high biological safety. Through a one-pot method, core-shell nanoparticles (HZIF-8) were synthesized. This structure enables efficient immobilization of lysozyme and lactoferrin within the HZIF-8, resulting in the formation of the lysozyme-lactoferrin@HZIF-8 (LYZ-LF@HZIF-8) composite. Upon exposure to light irradiation, HZIF-8 itself possessed antibacterial properties. Lysozyme initiated the degradation of bacterial peptidoglycan and lactoferrin synergistically enhanced the antibacterial effect of lysozyme. All of the above ultimately contributed to comprehensive antibacterial activity. Antibacterial assessments demonstrated the efficacy of the LYZ-LF@HZIF-8 composite, effectively eradicating Staphylococcus aureus at a cell density of 1.5 × 106 CFU/mL with a low dosage of 200 μg/mL and completely inactivating Escherichia coli at 400 μg/mL with the same cell density. The enzyme-MOF composite exhibited significant and durable antibacterial efficacy, with no apparent cytotoxicity in vitro, thereby unveiling expansive prospects for applications in the medical and food industries.

Poly(N-Heterocyclic Carbene)-Capped Alloy and Core-Shell AuAg Bimetallic Nanoparticles.

N-Heterocyclic carbene (NHC)-stabilized metal nanoparticles (NPs) have recently attracted considerable attention. While most efforts in the field have been devoted to the development of NHC-tethered monometallic NPs and enhancing their stabilities under various conditions, their bimetallic counterparts are rare in the literature. Herein, we demonstrate that the covalent immobilization of Au and Ag atoms on polymerized NHCs is a powerful method to access bimetallic AuAg NPs. In addition, we show that while AuAg alloy NPs are often obtained via this method, the use of bimetallic polymeric substrates with lower Ag content, relative to Au, results in the formation of core-shell NPs with Au core and Ag shell. Application of these nanomaterials for oxygen reduction reaction is demonstrated with all materials exhibiting electrocatalytic activity. This work demonstrates for the first time that while bimetallic poly(NHC-metal)s are viable substrates to access NHC-stabilized bimetallic NPs, careful adjustment of metal content in the polymeric substrates can finetune the microstructure of the resulting NPs, i.e. alloy vs. core-shell.

Amorphous-Co@Nd(BO2)3/rGO magnetic nanocomposites as high-frequency, wide-bandwidth and light-weight microwave absorbing materials

It is necessary to broaden absorption bandwidth, regulate applied frequency, reduce the weight and maintain strong absorption for magnetic microwave absorbing materials by constructing suitable material structures to satisfy the requirements for wide applications in various electromagnetic devices. In this work, well-structured amorphous-Co@Nd(BO2)3/rGO nanocomposites have been fabricated using a selective chemical reduction in a mixed aqueous solution containing Co2+ and Nd3+ ions along with GO sheets reduced by NaBH4 as the reductant, in which only Co2+ and GO but no Nd3+ ions were reduced. Very low coercivity of 0.4 Oe is achieved in amorphous-Co@Nd(BO2)3/rGO nanocomposites due to amorphous Co@Nd(BO2)3 core-shell nanoparticles uniformly anchored on rGO sheets. These soft magnetic rGO-based nanocomposites exhibit high-frequency microwave absorption performance including a minimum reflection loss (RLmin) value of −84.09 dB at 15.38 GHz for a 2.1 mm thickness at an applied frequency range (12.31–18 GHz) covering almost the entire Ku band. Moreover, a much wider absorption band of 7.24 GHz (10.67–17.89 GHz, RL ≤ −10 dB) with a 2.3 mm thickness along with a RLmin value of −35.92 dB is also achieved. These rGO-based magnetic composites also show good structural stability, low density and easily controlled material compositions along with facile chemical fabrication suitable for mass production, which promises their latent use in high-performance microwave absorbing devices. Crystallization behavior of a new amorphous Nd(BO2)3 phase was also investigated.

Ag@Au and Au@Ag Core–Shell Nanoparticles: Insights on the Growth Process and Interactions with Small Molecules

Ag@Au and Au@Ag Core–Shell Nanoparticles: Insights on the Growth Process and Interactions with Small Molecules

Synthesis and self-assembly of poly(4-vinylphenol)-b-poly(vinyl alcohol) diblock copolymer for invertible core-shell nanoparticles

We report the synthesis of the amphiphilic diblock copolymer, poly (vinyl phenol)-block-poly (vinyl alcohol), and its reversible formation of invertible core-shell nanoparticles. The diblock copolymer composed of poly (4-vinylphenol) (P4VPh) and poly (vinyl alcohol) (PVA) was prepared by the switchable reversible addition-fragmentation chain transfer polymerization (switchable-RAFT) of 4-acetoxystyrene and vinyl acetate and subsequent acetyl deprotection. The diblock copolymer was soluble in dimethyl sulfoxide (DMSO) but self-assembled into core-shell nanoparticles with the addition of H2O or tetrahydrofuran (THF). The formation and transition of the invertible core-shell system in response to solvent composition was characterized by 1H NMR, dynamic light scattering, and transmission electron microscopy. Interestingly, the fluorescent behavior of the P4VPh block was changed according to the morphological change of core-shell nanoparticle induced by solvent composition. With increasing the H2O content, the P4VPh chains in the DMSO solution collapsed and the diblock copolymers self-assembled to core-shell type micelles. Aggregation of P4VPh chains increased the local concentration of the phenolic group, resulting in fluorescence quenching. However, with the addition of THF to the DMSO solution, the inverted core-shell nanoparticles were formed where segregated P4VPh chains showed fluorescence.

A Method for Determining Incorporation Depth in Core-Shell UiO-66 Nanoparticles Synthesized Via Postsynthetic Exchange.

Postsynthetic exchange (PSE) is a key technique for integrating sensitive linkers into metal-organic frameworks (MOFs). Despite its importance, investigations into linker distributions have primarily focused on micrometer-sized crystals due to the analytical limitations, leaving nanoparticles less explored, although they are commonly synthesized and used in applications. In particular, the emergence of core-shell nanostructures via PSE has shown potential for applications in CO2 adsorption and selective catalysis. This study addresses this gap by investigating the formation of core-shell structures on nanoparticles under diffusion-controlled PSE conditions. By analyzing volume-to-surface ratios and conducting time-dependent experiments, we confirmed that these conditions facilitate the development of core-shell architectures. We also developed a straightforward method to calculate the minimum incorporation depth using basic parameters such as particle size and the total amount of incorporated linker. The accuracy of our approach was validated against data obtained from transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy. These findings enhance the understanding of PSE in MOF nanoparticles and open up promising avenues for developing advanced MOF core-shell structures for various applications.

Development of elliptic core-shell nanoparticles with fluorinated surfactants for 19F MRI.

Perfluorocarbon-encapsulated silica nanoparticles possess attractive features such as biological inertness and favorable colloidal properties for bioimaging with fluorine magnetic resonance imaging (19F MRI). Herein, a series of elliptic shaped silica nanoparticles with perfluorocarbon liquid perfluoro-15-crown-5 ether as core (PFCE@SiO2) were synthesized using fluorinated surfactants N-(perfluorononylmethyl)-N,N,N-trimethylammonium chloride (C10-TAC) and N-(perfluoroheptylmethyl)-N,N,N-trimethylammonium chloride (C8-TAC). The nanoparticles are characterized to obtain elliptic core-shell structures. PFCE@SiO2 showed strong 19F NMR signals of the encapsulated PFCE, indicating the potential as a highly sensitive 19F MRI probe. These elliptic PFCE@SiO2 nanoparticles provide a new option of 19F MRI probe with a morphology different from conventional nanospheres.

Design and Characterization of a Novel Core-Shell Nano Delivery System Based on Zein and Carboxymethylated Short-Chain Amylose for Encapsulation of Curcumin.

Curcumin is a naturally occurring hydrophobic polyphenolic compound with a rapid metabolism, poor absorption, and low stability, which severely limits its bioavailability. Here, we employed a starch-protein-based nanoparticle approach to improve the curcumin bioavailability. This study focused on synthesizing nanoparticles with a zein "core" and a carboxymethylated short-chain amylose (CSA) "shell" through anti-solvent precipitation for delivering curcumin. The zein@CSA core-shell nanoparticles were extensively characterized for physicochemical properties, structural integrity, ionic stability, in vitro digestibility, and antioxidant activity. Fourier-transform infrared (FTIR) spectroscopy indicates nanoparticle formation through hydrogen-bonding, hydrophobic, and electrostatic interactions between zein and CSA. Zein@CSA core-shell nanoparticles exhibited enhanced stability in NaCl solution. At a zein-to-CSA ratio of 1:1.25, only 15.7% curcumin was released after 90 min of gastric digestion, and 66% was released in the intestine after 240 min, demonstrating a notable sustained release effect. Furthermore, these nanoparticles increased the scavenging capacity of the 1,1-diphenyl-2-picrylhydrazyl (DPPH•) free radical compared to those composed solely of zein and were essentially nontoxic to Caco-2 cells. This research offers valuable insights into curcumin encapsulation and delivery using zein@CSA core-shell nanoparticles.

Fabrication and Advanced Imaging Characterization of Magnetic Aerogel-Based Thin Films for Water Decontamination.

Aerogels have emerged as appealing materials for various applications due to their unique features, such as low density, high porosity, high surface area, and low thermal conductivity. Aiming to bring the advantages of these materials to the environmental field, this study focuses on synthesizing magnetic silica aerogel-based films suitable for water decontamination. In this respect, a novel microfluidic platform was created to obtain core-shell iron oxide nanoparticles that were further incorporated into gel-forming precursor solutions. Afterward, dip-coating deposition was utilized to create thin layers of silica-based gels, which were further processed by 15-hour gelation time, solvent transfer, and further CO2 desiccation. A series of physicochemical analyses (XRD, HR-MS FT-ICR, FT-IR, TEM, SEM, and EDS) were performed to characterize the final films and intermediate products. The proposed advanced imaging experimental model for film homogeneity and adsorption characteristics confirmed uniform aerogel film deposition, nanostructured surface, and ability to remove pesticides from contaminated water samples. Based on thorough investigations, it was concluded that the fabricated magnetic aerogel-based thin films are promising candidates for water decontamination and novel solid-phase extraction sample preparation.

Uncovering the three-dimensional structure of upconverting core–shell nanoparticles with multislice electron ptychography

Uncovering the three-dimensional structure of upconverting core–shell nanoparticles with multislice electron ptychography

Magnetic alginate core-shell nanoparticles based on Schiff-base imine bonding for pH-responsive doxorubicin delivery system

This research describes the development of a novel pH-responsive drug delivery system (DDS) based on sodium alginate (SA) and magnetic nanoparticles (MNPs) for cancer treatments. One possible approach to creating a wide variety of functional nanoparticles is to graft functional materials onto magnetite nanoparticles. In this study, we demonstrate the effective alteration of Fe3O4 nanoparticles using the alginate dialdehyde (ADA) group through a Schiff-Base imine reaction toward synthesizing Fe3O4@SiO2@APTMS@ADA (FSA@ADA) nanocarrier (NC). doxorubicin (DOX) as an anticancer drug was loaded (about 93 % drug loading capacities) on the FSA@ADA NC through chemical and physical interactions. doxorubicin (DOX) as an anticancer drug was loaded (about 93 % drug loading capacities) on the FSA@ADA NC through chemical and physical interactions. The synthesized nanocarriers were thoroughly characterized by various techniques, including FT-IR, FE-SEM, EDX-MAP, TEM, XRD, VSM, TGA, and 1HNMR. In vitro DOX release studies showed a pH-dependent manner and its release rate is lower (< 15 %) at 7.4 than pH 5 (about 75 %) over 25 days. Cytotoxicity results showed good biocompatibility for blank FSA@ADA (over about 85 % cell viability), whereas DOX-loaded FSA@ADA NCs had higher cytotoxic effects (IC50 value: ∼6 µg/mL) as a result of the controlled release of DOX into HeLa cells. Results showed that the magnetic core-shell FSA@ADA/DOX NC has the potential to be used as a targeted stimuli-responsive drug for cancer treatment.

Facile synthesis of iron nanoparticles from Camellia Sinensis leaves catalysed for biodiesel synthesis from Azolla filiculoides

Recent years have seen an increase in research on biodiesel, an environmentally benign and renewable fuel alternative for traditional fossil fuels. Biodiesel might become more cost-effective and competitive with diesel if a solid heterogeneous catalyst is used in its production. One way to make biodiesel more affordable and competitive with diesel is to employ a solid heterogeneous catalyst in its manufacturing. Based on X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FTIR), the researchers in this study proved their hypothesis that iron oxide core–shell nanoparticles were generated during the green synthesis of iron-based nanoparticles (FeNPs) from Camellia Sinensis leaves. The fabrication of spherical iron nanoparticles was successfully confirmed using scanning electron microscopy (SEM). As a heterogeneous catalyst, the synthesised catalyst has shown potential in facilitating the conversion of algae oil into biodiesel. With the optimal parameters (0.5 weight percent catalytic load, 1:6 oil—methanol ratio, 60 °C reaction temperature, and 1 h and 30 min reaction duration), a 93.33% yield was attained. This may be due to its acid–base property, chemical stability, stronger metal support interaction. Furthermore, the catalyst was employed for transesterification reactions five times after regeneration with n-hexane washing followed by calcination at 650 °C for 3 h.

ZrC–Au core-shell nanoparticles for efficient solar photothermal conversion

Nanoparticles (NPs) have attracted much attention recently because of their excellent photothermal properties. In particular, nanofluids (NFs) based on core-shell plasmon NPs have become the key to solar thermal utilization. This work proposed an ZrC–Au core-shell NP suitable for direct absorption solar collectors (DASCs). The optical properties of ZrC–Au core-shell NP are investigated based on the finite element method (FEM). The physical mechanism of its existence can be explained by the surface plasmon resonance and localized surface plasmon resonance of ZrC–Au core-shell NP. Meanwhile, the effect of core-shell size on the NP optical properties of ZrC–Au core-shell is investigated based on electromagnetic field distribution. In addition, the effects of length (H) and mass flow (ṁ) on the temperature rise and efficiency of the collector (η) are analyzed with DASC 2D simulation. Research shows that ZrC–Au core-shell NPs with t = 5 nm and r3 = 15 nm can effectively broaden the solar spectral absorption band, increase the absorption peak value, and the photothermal conversion efficiency (fv = 20 ppm, h = 15 mm) reaches 96 %, which is 15.89 % higher than Au NP. Meanwhile, the η of ZrC–Au NPs can be improved by ∼8.86 % compared with Au NPs under specific parameters (H = 2 cm, L = 20 cm, fv = 20 ppm, ṁ = 1 g/(s m)). Combined with the preparation possibility and economy of ZrC–Au core-shell NPs, the broad application prospect of this NP in DASC and other photothermal fields was analyzed.

Effect of Temperature and Composition on the Loading of Curcumin into PLGA/PLLA Core–Shell Nanoparticles Stabilized by Hydrophobically Functionalized Polyelectrolytes

Effect of Temperature and Composition on the Loading of Curcumin into PLGA/PLLA Core–Shell Nanoparticles Stabilized by Hydrophobically Functionalized Polyelectrolytes

Numerical simulations of the optical properties of SiO2@Au core–shell nanoparticles: The effect of geometrical parameters on the tunability and sensitivity of their plasmon response

Based on systematic numerical simulations, the effect of geometrical parameters of SiO2@Au core-shells (nanoshells) on the tunability and sensitivity of their optical response was elucidated. The surface plasmon resonance (SPR) of nanoshells experiences a blueshift-redshift crossover with the increase in shell thickness, and this phenomenon is ascribed to the competition between the two effects, that is, the hybridization effect dominated in the thin shells and the retardation effect dominated in the thick shells. The relative strength of absorption/scattering in the extinction spectra and the relative strength of dipolar/multipolar modes can be selectively tuned by controlling the total volume of nanoshells. The sensitivity of the SPR peak wavelength to the shell thickness is primarily dependent on the core-to-shell ratio; the higher this ratio is, the larger the sensitivity. The tailorable properties of nanoshells make them promising and well-suited platforms in various applications.

Relationship between deposition techniques and nanoparticle dispersions for flexible and printed electronics

Reverse micelles composed of polystyrene-b-poly(2-vinylpyiridine) have been used to synthesize nanoparticles composed of a wide range of materials, including metals, metal oxides, dielectrics, semiconductors perovskites, and core–shell nanoparticles. In this contribution, we examine the effect of deposition parameters on two-dimensional nanoparticle arrangements from colloidal solutions created using spin coating, dip coating, slot-die coating, and electrospray deposition. Despite the importance of achieving uniform coatings of ordered arrays of colloidal particles, previous studies have not thoroughly addressed this challenge. We show that the adjustability of interparticle distance depends on the deposition technique used and only occurs within the stable defect-free operating window of the deposition parameters. Establishing the specific operating window for each technique for a model system, we propose general guidelines that can be used for ensuring uniform coatings regardless of precursor loading and provide a guide for adjusting the deposition conditions when coating defects occur. We introduces a novel application of ellipsometry to evaluate interparticle spacing in nanoparticle arrays, enhancing our ability to assess film uniformity, allowing for quick and easy tuning of nanoparticle dispersion. Comparisons between spin, dip, and slot-die coating techniques reveal insights into the correlation between interparticle spacing and ordering, highlighting the importance of fitting relationships for various coating samples. This comprehensive comparison and discussion provide a roadmap for future research, outlining current challenges and trends and offering insights into achievable spacings and ordering in coating processes. This allows the classification of various deposition techniques with respect to their suitability for tailored applications.

Inhibition of wax crystallization and asphaltene agglomeration by core-shell polymer@SiO2 hybride nano-particles

The gelation of crude oil with high wax and asphaltene content at low temperatures often results in the block of transportation pipeline in Africa. In recent years, it was reported that surface hydrophobic-modified nanoparticles have important applications in crude oil flow modification. In this work, four kinds of core-shell hybride nanoparticles by grafting poly (octadecyl, docosyl acrylate) and poly (acrylate-α-olefin) onto the surface of nano-sized SiO2 were synthesized by grafting polymerization method. The chemical structure of nanoparticles was analyzed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The rheological behaviors of crude oil and precipitation of asphaltenes in the presence of nanoparticles were studied by measuring the viscose-temperature relationship curve, the cumulative wax precipitation amount, and morphology of waxes and asphaltenes. The results indicate that the docosyl polyacrylate@SiO2 nanoparticle (PDA@SiO2) can reduce the cumulative wax precipitation amount of crude oil by 72.8%, decline the viscosity of crude oil by 85.6% at 20 °C, reduce the average size of wax crystals by 89.7%, and inhibit the agglomeration of asphaltene by 74.8%. Therefore, the nanoparticles not only adjust the crystalline behaviors of waxes, but also inhibit the agglomeration of asphaltenes. Apparently, core-shell hybride nanoparticles provides more heterogeneous nucleation sites for the crystallization of wax molecules, thus inhibiting the formation of three-dimensional network structure. The core-shell polymer@SiO2 hybride nanoparticles are one of promising additives for inhibiting crystallization of waxes and agglomeration of asphaltenes in crude oil.

Toxicity and magnetometry evaluation of the uptake of core-shell maghemite-silica nanoparticles by neuroblastoma cells.

Nanoparticle uptake by cells is a key parameter in their performance in biomedical applications. However, the use of quantitative, non-destructive techniques to obtain the amount of nanoparticles internalized by cells is still uncommon. We have studied the cellular uptake and the toxicity of core-shell maghemite-silica magnetic nanoparticles (MNPs), with a core diameter of 9 nm and a shell thickness of 3 nm. The internalization of the nanoparticles by mouse neuroblastoma 2a cells was evaluated by sensitive and non-destructive Superconducting Quantum Interference Device (SQUID) magnetometry and corroborated by graphite furnace atomic absorption spectroscopy. We were thus able to study the toxicity of the nanoparticles for well-quantified MNP uptake in terms of nanoparticle density within the cell. No significant variation in cell viability or growth rate was detected for any tested exposure. Yet, an increase in both the amount of mitochondrial superoxide and in the lysosomal activity was detected for the highest concentration (100 μg ml-1) and incubation time (24 h), suggesting the onset of a disruption in ROS homeostasis, which may lead to an impairment in antioxidant responses. Our results validate SQUID magnetometry as a sensitive technique to quantify MNP uptake and demonstrate the non-toxic nature of these core-shell MNPs under our culture conditions.

Efficient Immobilization of heavy metals using newly synthesized magnetic nanoparticles and some bacteria in a multi-metal contaminated soil.

Simultaneous application of modified Fe3O4 with biological treatments in remediating multi-metal polluted soils, has rarely been investigated. Thus, a pioneering approach towards sustainable environmental remediation strategies is crucial. In this study, we aimed to improve the efficiency of Fe3O4 as adsorbents for heavy metals (HMs) by applying protective coatings. We synthesized core-shell magnetite nanoparticles coated with modified nanocellulose, nanohydrochar, and nanobiochar, and investigated their effectiveness in conjunction with bacteria (Pseudomonas putida and Bacillus megaterium) for remediating a multi-metal contamination soil. The results showed that the coatings significantly enhanced the immobilization of heavy metals in the soil, even at low doses (0.5%). The coating of nanocellulose had the highest efficiency in stabilizing metals due to the greater variety of surface functional groups and higher specific surface area (63.86 m2 g-1) than the other two coatings. Interestingly, uncoated Fe3O4 had lower performance (113.6 m2 g-1) due to their susceptibility to deformation and oxidation. The use of bacteria as a biological treatment led to an increase in the stabilization of metals in soil. In fact, Pseudomonas putida and Bacillus megaterium increased immobilization of HMs in soil successfully because of extracellular polymeric substances and intensive negative charges. Analysis of metal concentrations in plants revealed that Ni and Zn accumulated in the roots, while Pb and Cd were transferred from the roots to the shoots. Treatment Fe3O4 coated with modified nanocellulose at rates of 0.5 and 1% along with Pseudomonas putida showed the highest effect in stabilizing metals. Application of coated Fe3O4 for in-situ immobilization of HMs in contamination soils is recommendable due to their high metal stabilization efficiency and suitability to apply in large quantities.

Optimized the SiO2 thickness in Ag@SiO2 core–shell nanoparticles for surface-enhanced Raman scattering and fluorescence

Optimized the SiO2 thickness in Ag@SiO2 core–shell nanoparticles for surface-enhanced Raman scattering and fluorescence