Core-shell Nanoparticles Research Articles

Black TiO2@Ag core-shell nanoparticles combined with WO3 nanorods on rGO nanosheets for PEC analysis

Well-coated black TiO2 and Ag core-shell nanoparticles (NPs) were prepared using a simple wet-chemical approach, which is combined with the WO3 nanorods over rGO nanosheets. The inherent properties of the composite nanostructures were examined thoroughly by diffuse reflectance spectroscopy, X-ray diffraction, Raman scattering, X-ray photoelectron spectroscopy, transmission electron microscopy, and photoelectrochemical (PEC) analysis. The formation of surface oxygen vacancies in the black TiO2 NPs facilitated tuning the optical properties in the visible region, which was enhanced by the surface plasmon resonance behavior of the Ag NPs. While combining the black TiO2@Ag core-shell NPs with intermediate bandgap WO3 nanorods and rGO nanosheets promoted PEC performance in the visible light irradiation. The composite nanostructure exhibited enhanced PEC efficiency (Jp=0.97 mAcm−2 and ABPE=0.62%) compared to the bare NPs. This work discusses the possible PEC mechanism based on the change in optical and structural properties.

Dual-targeting tigecycline nanoparticles for treating intracranial infections caused by multidrug-resistant Acinetobacter baumannii

Multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) is a formidable pathogen responsible for severe intracranial infections post-craniotomy, exhibiting a mortality rate as high as 71%. Tigecycline (TGC), a broad-spectrum antibiotic, emerged as a potential therapeutic agent for MDR A. baumannii infections. Nonetheless, its clinical application was hindered by a short in vivo half-life and limited permeability through the blood–brain barrier (BBB). In this study, we prepared a novel core–shell nanoparticle encapsulating water-soluble tigecycline using a blend of mPEG-PLGA and PLGA materials. This nanoparticle, modified with a dual-targeting peptide Aβ11 and Tween 80 (Aβ11/T80@CSs), was specifically designed to enhance the delivery of tigecycline to the brain for treating A. baumannii-induced intracranial infections. Our findings demonstrated that Aβ11/T80@CSs nanocarriers successfully traversed the BBB and effectively delivered TGC into the cerebrospinal fluid (CSF), leading to a significant therapeutic response in a model of MDR A. baumannii intracranial infection. This study offers initial evidence and a platform for the application of brain-targeted nanocarrier delivery systems, showcasing their potential in administering water-soluble anti-infection drugs for intracranial infection treatments, and suggesting promising avenues for clinical translation.Graphical abstract

Platinum/Tantalum Carbide Core–Shell Nanoparticles with Sub‐Monolayer Shells for Methanol and Oxygen Electrocatalysis

AbstractCore–shell architectures provide great opportunities to improve catalytic activity, but achieving nanoparticle stability under electrochemical cycling remains challenging. Herein, core–shell nanoparticles comprising atomically thin Pt shells over earth‐abundant TaC cores are synthesized and used as highly durable electrocatalysts for the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR) needed to drive direct methanol fuel cells (DMFCs). Characterization data show that a thin oxidic passivation layer protects the TaC core from undergoing dissolution in the fuel cell‐relevant potential range, enabling the use of partially covered Pt/TaC core–shell nanoparticles for MOR and ORR with high stability and enhanced catalytic performance. Specifically, at the anode the surface‐oxidized TaC further enhances MOR activity compared to conventional Pt nanoparticles. At the cathode, the Pt/TaC catalyst feature increases tolerance to methanol crossover. These results show unique synergistic advantages of the core–shell particles and open opportunities to tailor catalytic properties for electrocatalytic reactions.

Spatiotemporal tracking of intracellular nanoparticles using complementary imaging systems reveals acute ferroptosis triggered by burst reduction of ferric ions

Uptake and intracellular trafficking of nanoparticles are tightly regulated by their interactions with cellular organelles and physiological microenvironment. Although the dynamic physicochemical reactions at the interface of nanoparticles and cells ultimately determine the intracellular distribution and fate, microscopic tracing and quantitative analysis of the nanoparticles have been hampered by the limited resolution associated with individual nanoparticle trafficking. Herein, we report spatiotemporal investigations on autophagic clearance of biodegradable iron oxide-silica core-shell nanoparticles in terms of intracellular trafficking and ionic dissolution at a single cell level using multimodal imaging systems. By combining transmission electron microscopy and super-resolution confocal laser scanning microscopy with fluorescence correlation spectroscopy, the complementary imaging analysis exclusively shows the intracellular uptake, endosomal fusion and biodegradative clearance, leading to identify the step-by-step endocytic transport pathway and autophagic degradation pathways. Tracing the intracellular trafficking of nanoparticles reveals that they are spontaneously transported from endosomes to lysosomes, and transiently stimulate autophagy while maintaining cell viability. While protecting iron oxide core, the silica shell is gradually degraded during endocytosis and autophagic clearance, resulting in ionic dissolution of iron oxide in acidic environment. Moreover, burst reduction of ferric ions by adding ascorbic acid readily triggers acute ferroptosis owing to rapid supplement of ferrous ions and Fenton reaction in cancer cells. The complementary imaging strategy provides insights into the design of biocompatible nanomedicines for cellular delivery and the degradative mechanisms beyond the intracellular fate.

Light‐induced Delivery of Charged Species using Ion‐selective Core–Shell Nanoparticles

AbstractControlled release systems have gained considerable attention owing to their potential to deliver molecules, including ions and drugs, in a customized manner. We present a light‐induced ion‐transfer platform consisting of a dispersion of nanoparticles (NPs, ~300 nm) with the conductive polymer poly(3‐octylthiophene‐2,5‐diyl) (POT) in the core and a potassium (K+)‐selective membrane in the shell. Owing to the photoactive nature of POT, POT NPs can be used for a dual purpose: as a host for positively charged species and as an actuator to trigger the subsequent release. POT0 and doped POT+ coexist in the core, allowing K+ encapsulation in the shell. As POT0 is photo‐oxidized to POT+, K+ is released to the (aqueous) dispersion phase to preserve the neutrality of the NPs. This process is reversible and can be simultaneously assessed using the native fluorescence of POT0 and via potentiometric measurements. The NP structure and its mechanism of action were thoroughly studied with a series of control experiments and complementary techniques. Understanding the NP and its surrounding interactions will pave the way for other nanostructured systems, facilitating sophisticated applications. The delivery of ionic drugs and interference/pollutant catching for advanced sensing/restoration will be considered in future research.

Aqueous inks for ecofriendly processing of organic solar cells: Investigation of morphological changes

Aqueous dispersions of organic semiconducting nanoparticles (NPs) are particularly attractive as inks for the environmentally friendly preparation of organic solar cells. The internal morphology of the NPs, which depends on their elaboration process, is a key parameter, which has a significant influence on the final morphology of the active layer and therefore its effectiveness. In the present study, core-shell (PF2:PC71BM) NPs were prepared by miniemulsion. Their internal morphology including the composition of the two phases was characterized by scanning transmission X-ray microscopy (STXM) showing a core composed of 77% PC71BM and a shell composed of 75% PF2. It was found that thermal annealing promotes PC71BM diffusion from the core to the shell, increasing its proportion in the shell from 25% to 42%. This annealing, when applied after NPs deposition by spincoating, allows partial coalescence of the NPs, reducing the roughness of the active layer, and increases electron mobility, thus demonstrating the formation of PC71BM percolation paths for electron transport. A PCE of 1.6% could thus be obtained after 10 min of thermal annealing at 100°C. At higher temperature, Grazing-Incidence Wide-Angle X-Ray Scattering (GIWAXS) analyses demonstrate the modification of the PF2 structuration from randomly oriented lamella after deposition to edge-on orientation after annealing, leading to an unfavorable decrease of the hole mobility in the direction perpendicular to the substrate, while increasing the hole mobility in the substrate plane. This study demonstrates the need to systematically characterize the internal morphology of NPs in order to rationalize the morphology of the active layer and optimize its properties.

Light-induced Delivery of Charged Species using Ion-selective Core-Shell Nanoparticles.

Controlled release systems have gained considerable attention owing to their potential to deliver molecules, including ions and drugs, in a customized manner. We present a light-induced ion-transfer platform consisting of a dispersion of nanoparticles (NPs, ~300 nm) with the conductive polymer poly(3-octylthiophene-2,5-diyl) (POT) in the core and a potassium (K+)-selective membrane in the shell. Owing to the photoactive nature of POT, POT NPs can be used for a dual purpose: as a host for positively charged species and as an actuator to trigger the subsequent release. POT0 and doped POT+ coexist in the core, allowing K+ encapsulation in the shell. As POT0 is photo-oxidized to POT+, K+ is released to the (aqueous) dispersion phase to preserve the neutrality of the NPs. This process is reversible and can be simultaneously assessed using the native fluorescence of POT0 and via potentiometric measurements. The NP structure and its mechanism of action were thoroughly studied with a series of control experiments and complementary techniques. Understanding the NP and its surrounding interactions will pave the way for other nanostructured systems, facilitating sophisticated applications. The delivery of ionic drugs and interference/pollutant catching for advanced sensing/restoration will be considered in future research.

Single AgNF@ZIF-8 nanoparticle for deep learning assisted SERS detection of gaseous molecule

Random nanogaps between plasmonic nanoparticles formed by the surface tension of solution bring a great challenge in the application of Surface Enhanced Raman Spectroscopy (SERS) technique. Meanwhile, due to its natural nanogaps on the surface, single plasmonic nanoflower exhibits a unique charm for avoiding random gaps in the quantitative analysis of SERS. Herein, a single core-shell plasmonic nanoparticle consisting of an Ag nanoflower (AgNF) core and zeolite imidazolate frame-8 (ZIF-8) shell is synthesized for SERS detection of the gaseous molecule. Benefiting the porous shell of ZIF-8 to capture gaseous molecules and natural nanogaps on the surface of AgNF to enhance Raman intensity, SERS spectra of the gaseous molecule are successfully collected with high sensitivity at 10−6 M, which also exhibit high SERS stability with RSD at 2.29 % for single nanoparticle and 9.86 % for multiple single nanoparticles. In addition, two levels of automatic identification based on deep learning (DL) are also implemented in this work, whose data demonstrate artificial neural network (ANN) algorithm could identify gaseous glutaraldehyde (GA) as typical volatile organic compounds (VOCs) with high accuracy at 97.5 %. This single core-shell plasmonic MOF nanoparticle overcomes the limitations of traditional SERS detection in nanoparticle aggregating and realizes the detection of gaseous molecules, which enlarges the application of SERS technique.

Optimizing Carbon-Based Perovskite Solar Cells with Pyramidal Core–Shell Nanoparticles for High Efficiency

Optimizing Carbon-Based Perovskite Solar Cells with Pyramidal Core–Shell Nanoparticles for High Efficiency

Self-assembled core-shell nanoparticles with embedded internal standards for SERS quantitative detection and identification of nicotine released from snus products.

Surface enhanced Raman spectroscopy (SERS) is a unique analytical technique with excellent performance in terms of sensitivity, non-destructive detection and resolution. However, due to the randomness and poor repeatability of hot spot distribution, SERS quantitative analysis is still challenging. Meanwhile, snus is a type of tobacco product that can release nicotine and other components in the mouth without burning, and the rapid detection technique based on SERS can reliably evaluate the amount of nicotine released from snus, which is of great significance for understanding its characteristics and regulating its components. Herein, the strategy was proposed to solve the feasibility of SERS quantitative detection based on self-assembled core-shell nanoparticles with embedded internal standards (EIS) due to EIS signal can effectively correct SERS signal fluctuations caused by different aggregation states and measurement conditions, thus allowing reliable quantitative SERS analysis of targets with different surface affinity. By means of process control, after the Au nanoparticles (Au NPs) were modified with 4-Mercaptobenzonitrile (4-MBN) as internal standard molecules, Ag shell with a certain thickness was grown on the surface of the AuNP@4-MBN, and then the Au@4-MBN@Ag NPs were used to regulate and control the assembly of liquid-liquid interface. The high-density nano-arrays assembled at the liquid-liquid interface ensure high reproducibility as SERS substrates, and which could be used for SERS detection of nicotine released from snus products. In addition, time-mapping research shows that this method can also be used to dynamically monitor the release of nicotine. Moreover, such destruction-free evaluation of the release of nicotine from snus products opens up new perspectives for further research about the impact of nicotinoids-related health programs.

NIR laser effect on cancer cell lines activity by using Fe3O4@Cu@SiO2 core–shell nanoparticles

NIR laser effect on cancer cell lines activity by using Fe3O4@Cu@SiO2 core–shell nanoparticles

Effect of Tunable Dielectric Core on Optical Bistability in Cylindrical Core–Shell Nanocomposites

In this paper, the effect of a tunable dielectric core on local field enhancement, induced optical bistability, and the optical bistability domain in cylindrical core–shell nanoparticle composites are studied. The local field enhancement factor increases significantly at two resonant frequencies. The results demonstrate that the local field enhancement factor in the cylindrical core–shell nanoparticle increases when the natural attribute of the dielectric function of the dielectric core is varied by adding a dielectric function to it. Furthermore, we demonstrated that the magnitude of the imaginary part of the active dielectric core increases as the onset and offset input intensities increase. This indicates that the optical bistability or threshold width range widens as the imaginary part of the dielectric function of the dielectric core increases, thereby enlarging the threshold domain to improve system activation.

Temperature-Controlled Molecular Bonding Hysteresis: Interphase Dynamics of a Nanoparticle-Modified Polymer Network.

This study demonstrates the existence of temperature-induced molecular bonding hysteresis at nanoparticle-polymer interfaces in a highly cross-linked epoxy-based polymer, modified with core-shell rubber nanoparticles. This thermally induced bond hysteresis manifests itself in a hysteresis-like change of the strength of the electrical bond polarization between epoxy molecules and surface molecules of the core-shell nanoparticles. This kind of dynamic bond behavior can be controllably switched from one bond state to the other by a sufficient temperature change. The related optical remanence is evidenced by a refractive index hysteresis independent of the temperature change using the new experimental technique of temperature-modulated optical refractometry (TMOR). From the investigation of quasi-static and dynamic thermal expansion separately, TMOR allows for the conclusion that the observed hysteresis is caused by the specific refractivity and not the dipole number density.

Insights into the role of ionic surfactants on the morphology of gold and gold@silver nanoparticles

Cyanidin-3, 5-di-O-glycoside (anthocyanin) was extracted from the red rose flower petals in an aqueous media. Anthocyanin was used as reductant to the preparation of gold nanoparticles with cationic and anionic surfactants. UV–visible absorption spectroscope, transmission electron microscope, scanning electron microscope, and energy dispersive X-ray spectroscope were employed to determine absorption bands of anthocyanin, surface Plasmon resonance (SPR) band, and morphology of the gold and gold@silver nanoparticles. Anthocyanin exhibited two absorption peaks at 284 and 518 nm, and one shoulder at 328 nm in the UV–visible spectrum. The intensity of these peaks decreases with time after the addition of HAuCl4. The color and the position of SPR band of gold nanoparticles depend on the concentration of gold salt with and without cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS). The anionic and cationic head groups of SDS and CTAB micelles have significant impact of the morphology of gold nanoparticles. Seedless co-reduction method was used for the synthesis of gold@silver nanoparticles. TEM images clearly indicate the formation of bimetallic gold@silver core-shell nanoparticles. The antioxidant power of AuNPs and gold@silver nanoparticles were tested in terms of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity as a function of different concentrations of nanoparticles.

Encapsulation of orange-derived hesperetin in zein/pectin nanoparticles: Fabrication, characterization, stability, and bioaccessibility

Orange pomace is a byproduct of the orange juicing industry that contains several polyphenols that can exert health benefits. However, incorporating orange pomace polyphenols into functional foods is challenging because of their poor water solubility and low bioaccessibility. This problem can be overcome by incorporating the polyphenols into protein nanoparticle-based delivery systems. The objective of this research was therefore to encapsulate hesperetin in core-shell biopolymer nanoparticles assembled from zein and high-methoxy pectin using an antisolvent precipitation/electrostatic deposition method. Hesperetin is a bioactive polyphenol derived from hesperidin, which can be isolated from orange pomace. Fluorescence spectroscopy indicated a strong interaction between hesperetin and zein. Fourier transform infrared spectroscopy suggested that this interaction was primarily due to hydrogen bonding and hydrophobic interactions, while the interaction between pectin and zein was mainly due to electrostatic attraction. Hesperetin-loaded zein nanoparticles had a mean diameter, zeta-potential, and encapsulation efficiency of 179 nm, 23.2 mV, and 93% before coating with pectin, and 357 nm, −22.6 mV, and 94% after coating with pectin, respectively. The pectin coating improved the stability of the nanoparticles to aggregation and sedimentation under different environmental conditions: pH 2.0–8.0; temperatures up to 90 °C; salt levels up to 50 mM NaCl; and storage for up to one month. The antioxidant activity and in vitro bioaccessibility of the encapsulated hesperetin were significantly higher than hesperetin dispersed in water. These results show that core-shell biopolymer nanoparticles may be a promising approach to incorporate hesperetin (and possibly other polyphenols) into foods and beverages.

Analysis of the Inhomogeneous Growth of Sputtered Black TiO2 Thin Films.

Black titanium dioxide (B-TiO2) is a highly active photoelectrochemical material compared to pure titanium dioxide due to its increased light absorption properties. Recently, we presented the deposition of thin-film B-TiO2 using an asymmetric bipolar reactive magnetron sputter process. The resulting samples exhibit excellent photoelectrochemical properties, which can be fine-tuned by varying the process parameters. In this article, results of morphological, electrical, and photoelectrochemical measurements are discussed to better understand the surprisingly high electrochemical activity of the films. In order to study the influence of the dynamic process on film formation, we use static sputtering with a fixed substrate covering the entire chamber area in front of the two targets. This allows the material composition of the sputtered film to be analyzed depending on its relative position to the targets. The results lead to the conclusion that the asymmetric bipolar sputtering mainly produces two phases, a transparent, nonconductive crystalline phase and a black, conductive amorphous phase. As a consequence, the dynamically sputtered samples are multilayers of these two materials. We discuss that the significantly better electrical and photoelectrochemical properties emerge from the inhomogeneous nature of the laminates, like also found in core-shell nanoparticles of B-TiO2.

Unraveling the effect of annealing on the structural and microstructural evolution of NiFe2O4@SiO2 core-shell type nanocomposites

The comparison between as-received and multistage annealed NiFe2O4@SiO2 (NFO@SiO2) core-shell nanoparticles is presented. The studied ferrites were synthesized by co-precipitation followed by microemulsion. The presence of cubic inverse spinel ferrite structure with tetrahedral and octahedral iron occupancy is confirmed in all analyzed samples. The structural characterization revealed the gradual crystallization of NFO cores up to about 12 nm crystallite size at the last annealing stage. Simultaneously, a partial crystallization of the silica matrix is evidenced. The superparamagnetic (SPM) behaviour is demonstrated based on complex magnetic performance and confirmed by Mössbauer spectrometry. The spin-canting phenomenon on the surface dead magnetic layer (MDL) is revealed based on the Yafet-Kittel model. A slight change in MDL thickness versus heat treatment is proved. The X-ray photoemission and absorption studies confirmed the complex nature of the Fe-based states. The Si–O–Ni/Fe intermixing on the NFO – SiO2 nanoparticles interface is revealed by the core-level lines analysis, proving the existence of a disordered layer on the NFO surface.

Lipid-Polymer Hybrid Nanoparticles Synthesized via Lipid-Based Surface Engineering for a robust drug delivery platform

Herein, lipid-polymer core-shell hybrid nanoparticles composed of poly(D,L-lactic-co-glycolic acid) (PLGA)/lecithin (PLNs) were synthesized through lipid-based surface engineering. Lipids were absorbed onto the surface of the PLGA core to enhance the advantages of polymeric nanoparticles and liposomes. The amounts of lipids and encapsulation of the drug nicardipine hydrochloride (NCH) in the PLNs were studied. NCH-loaded PLNs (NCH-PLNs) were produced in high yield (66%) with a high encapsulation efficiency (92%) and a size of 176 nm. The mass of phosphorus (P) on the NCH-PLN surface was qualitatively and quantitatively investigated using X-ray fluorescence spectroscopy, and lecithin addition increased the P mass percentage due to the phosphate group (PO43-) in its structure. These data confirmed the lipid-based surface engineering of NCH-PLNs. The zeta potential of NCH-PLN exceeded −30 mV, ensuring colloidal stability, and preventing precipitation through electrostatic stabilization. In vitro, NCH was continuously and slowly released from NCH-PLNs over 16 days. Furthermore, PSVK1 cells exhibited high viability after treatment with NCH-PLNs, indicating favorable cytocompatibility. After comparing various mathematical equations of drug release kinetics, the data best fit the Korsmeyer-Peppas model with R2 values of 0.989, 0.990, and 0.982 for 1.0, 3.0, and 5.0 mg/mL lecithin, respectively. The release exponents obtained ranged from 0.480 to 0.505, suggesting anomalous transport release. Thus, NCH-PLNs have potential as a robust drug delivery platform for the controlled administration of NCH, particularly for vasodilation during neurosurgery.

Core-shell designed high entropy alloy CoNiFeCuV-C nanoparticles for enhanced microwave absorption

The widespread interest in high entropy alloy nanostructures stems from their potential utilization in a variety of technological and scientific fields. This study presents an innovative approach employing a one-step metal organic chemical vapor deposition to synthesize quinary high entropy alloy (CoNiFeCuV-C) core-shell nanoparticles designed for microwave absorption applications. Superior microwave absorption performance is attained through the optimization of conduction loss via thermal treatment, coupled with the interfacial polarization across the interfaces between CoNiFeCuV cores and C shell. The paraffin composite filled with an optimal 20% content of CoNiFeCuV-C core-shell nanoparticles demonstrates a minimal reflection loss (RLmin) of −51.8 dB at 13.76 GHz, achieving this performance with a thickness of 2.2 mm. Moreover, the absorbing bandwidth spans 7.44 GHz at a thickness of 2.4 mm. The outstanding accomplishments underscore the potential of utilizing CoNiFeCuV-C core-shell nanoparticles as a promising choice for lightweight, effective microwave absorber material.

Determining Quasi-Equilibrium Electron and Hole Distributions of Plasmonic Photocatalysts Using Photomodulated X-ray Absorption Spectroscopy.

Most photocatalytic and photovoltaic devices operate under broadband, constant illumination. Electron and hole dynamics in these devices, however, are usually measured by using ultrafast pulsed lasers in a narrow wavelength range. In this work, we use excited-state X-ray theory originally developed for transient X-ray experiments to study steady-state photomodulated X-ray spectra. We use this method to attempt to extract electron and hole distributions from spectra collected at a nontime-resolved synchrotron beamline. A set of plasmonic metal core-shell nanoparticles is designed as the control experiment because they can systematically isolate photothermal, hot electron, and thermalized electron-hole pairs in a TiO2 shell. Steady-state changes in the Ti L2,3 edge are measured with and without continuous-wave illumination of the nanoparticle's localized surface plasmon resonance. The results suggest that within error the quasi-equilibrium carrier distribution can be determined even from relatively noisy data with mixed excited-state phenomena. Just as importantly, the theoretical analysis of noisy data is used to provide guidelines for the beamline development of photomodulated steady-state spectroscopy.