Core-shell Hybrid Nanoparticles Research Articles

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.

Water-Soluble Hybrid Core–Shell Nanoparticles with Titanium Dioxide Core and Poly(Acrylic Acid) Shell

Water-Soluble Hybrid Core–Shell Nanoparticles with Titanium Dioxide Core and Poly(Acrylic Acid) Shell

Optoelectronic tuning of plasmon resonances via optically modulated hot electrons.

Fast optical modulation of nanoplasmonics is fundamental for on-chip integration of all-optical devices. Although various strategies have been proposed for dynamic modulation of surface plasmons, critical issues of device compatibility and extremely low efficiency in the visible spectrum hamper the application of optoplasmonic nanochips. Here we establish an optoplasmonic system based on Au@Cu2-xS hybrid core-shell nanoparticles. The optical excitation of hot electrons and their charge transfer to the semiconductor coating (Cu2-xS) lead to lowered electron density of Au, which results in the red shift of the localized surface plasmon resonance. The hot electrons can also transport through the Cu2-xS layer to the metal substrate, which increases the conductance of the nanogap. As such, the coupled gap plasmon blue-shifts with a magnitude of up to ∼15nm, depending on the excitation power and the thickness of the coatings, which agrees with numerical simulations. All of this optoelectronic tuning process is highly reversible, controllable and fast with a modulated laser beam, which is highly compatible and sufficiently useful for on-chip integration of nanophotonic devices.

Self-Assembly of Core-Shell Hybrid Nanoparticles by Directional Crystallization of Grafted Polymers.

Nanoparticle self-assembly is an efficient bottom-up strategy for the creation of nanostructures. In a typical approach, ligands are grafted onto the surfaces of nanoparticles to improve the dispersion stability and control interparticle interactions. Ligands then remain secondary and usually are not expected to order significantly during superstructure formation. Here, we investigate how ligands can play a more decisive role in the formation of anisotropic inorganic-organic hybrid materials. We graft poly(2-iso-propyl-2-oxazoline) (PiPrOx) as a crystallizable shell onto SiO2 nanoparticles. By varying the PiPrOx grafting density, both solution stability and nanoparticle aggregation behavior can be controlled. Upon prolonged heating, anisotropic nanostructures form in conjunction with the crystallization of the ligands. Self-assembly of hybrid PiPrOx@SiO2 (shell@core) nanoparticles proceeds in two steps: First, the rapid formation of amorphous aggregates occurs via gelation, mediated by the interaction between nanoparticles through grafted polymer chains. As a second step, slow radial growth of fibers was observed via directional crystallization, governed by the incorporation of crystalline ribbons formed from free polymeric ligands in combination with crystallization of the covalently attached ligand shell. Our work reveals how crystallization-driven self-assembly of ligands can create intricate hybrid nanostructures.

Self-assembled morphology-controlled hierarchical Fe3O4 @LDH for Cr(VI) removal

The efficient removal of Cr(VI) in water with high solubility and mobility is of great significance because Cr(VI) is one of the most toxic heavy metals, but it also faces some major challenges. The dispersibility and recyclability of nanoadsorbents are closely related to their Cr(VI) removal efficiency. Herein, the self-assembly method was used to synthesize core-shell hybrid nanoparticles, named Fe3O4 @LDH, with a vertically aligned layered double hydroxide (MgAl-LDH) nanosheet shell and a Fe3O4 magnetite core. The obtained Fe3O4 @LDH nanoparticles exhibit a highly porous and well-ordered three-dimensional core-shell structure with a wool-ball-like morphology. The self-assembled morphology of the core-shell structure can be effectively controlled and induced by regulating the Mg2+/Al3+ ratio of the reaction system. The influence mechanism of charge density of LDH brucite-like layers on the self-assembled morphology was proposed. Fe3O4 @LDH nanoparticles exhibit a Cr(VI) adsorption capacity of 108.7 mg/g. The synergetic contribution of the hybrid self-assembly of Fe3O4 and MgAl-LDH leads to more dispersion, better adsorption capability, and faster kinetics. Moreover, because of the super-paramagnetic and highly saturated magnetization (34.53 emu/g) of the Fe3O4 @LDH nanoparticles, they can be used as efficient magnetic adsorbents and easily separated using a magnetic field and reused. The prepared Fe3O4 @LDH nanoparticles are a cost-effective nanoadsorbent for removing Cr(VI) from wastewater and provide a reference for the structural design and construction of nanocomposites.

Metal-Enhanced Fluorescence for Alpha-Fetoprotein Detection and for SERS Using Hybrid Nanoparticles of Magnetic Cluster Core—Plasmonic Shell Composite

We demonstrated that the hybrid core–shell nanostructure of Fe3O4 (core) and gold (shell) could be a good substrate candidate both for metal-enhanced fluorescence (MEF) and surface-enhanced Raman spectroscopy (SERS). The magnetic properties of the core material could provide functionalities such as the magnetically induced aggregation/distribution of nanostructures to increase the hot-spot density, while the nano-thickness gold shell allows for the plasmonic enhancement of both fluorescence and SERS. The gold-capped magnetic (Fe3O4) nanoparticles (GMPs) were facilely synthesized using a newly developed chemical method. The relative molar ratio of the constituent materials of the core–shell composite was optimized for tuning the plasmonic resonance wavelengths for MEF and SERS. We employed GMP-based MEF to detect alpha-fetoprotein (AFP), with concentrations ranging from 0.05 to 1000 ng/mL, and obtained a limit of detection (LOD) as low as 3.8 × 10−4 ng/mL. The signal enhancement factor (EF) in the GMP-based MEF was 1.5 at maximum. In addition, the GMPs were used in SERS to detect rhodamine B (RhB). Its LOD was 3.5 × 10−12 M, and the EF was estimated to be about 2 × 108. The hybrid core–shell nanoparticles could find potential applications in diagnostic assays based on MEF and SERS in various fields such as food verification, environmental testing/monitoring, and disease diagnosis.

Hybrid core-shell nanoparticles for cell-specific magnetic separation and photothermal heating.

Hyperthermia, as the process of heating a malignant site above 42 °C to trigger cell death, has emerged as an effective and selective cancer therapy strategy. Various modalities of hyperthermia have been proposed, among which magnetic and photothermal hyperthermia are known to benefit from the use of nanomaterials. In this context, we introduce herein a hybrid colloidal nanostructure comprising plasmonic gold nanorods (AuNRs) covered by a silica shell, onto which iron oxide nanoparticles (IONPs) are subsequently grown. The resulting hybrid nanostructures are responsive to both external magnetic fields and near-infrared irradiation. As a result, they can be applied for the targeted magnetic separation of selected cell populations - upon targeting by antibody functionalization - as well as for photothermal heating. Through this combined functionality, the therapeutic effect of photothermal heating can be enhanced. We demonstrate both the fabrication of the hybrid system and its application for targeted photothermal hyperthermia of human glioblastoma cells.

High drug loading polymer micelle@ZIF-8 hybrid core—shell nanoparticles through donor—receptor coordination interaction for pH/H2O2-responsive drug release

High drug loading polymer micelle@ZIF-8 hybrid core—shell nanoparticles through donor—receptor coordination interaction for pH/H2O2-responsive drug release

Hybrid Nanoparticles and Composite Hydrogel Systems for Delivery of Peptide Antibiotics.

The growing number of drug-resistant pathogenic bacteria poses a global threat to human health. For this reason, the search for ways to enhance the antibacterial activity of existing antibiotics is now an urgent medical task. The aim of this study was to develop novel delivery systems for polymyxins to improve their antimicrobial properties against various infections. For this, hybrid core–shell nanoparticles, consisting of silver core and a poly(glutamic acid) shell capable of polymyxin binding, were developed and carefully investigated. Characterization of the hybrid nanoparticles revealed a hydrodynamic diameter of approximately 100 nm and a negative electrokinetic potential. The nanoparticles demonstrated a lack of cytotoxicity, a low uptake by macrophages, and their own antimicrobial activity. Drug loading and loading efficacy were determined for both polymyxin B and E, and the maximal loaded value with an appropriate size of the delivery systems was 450 µg/mg of nanoparticles. Composite materials based on agarose hydrogel were prepared, containing both the loaded hybrid systems and free antibiotics. The features of polymyxin release from the hybrid nanoparticles and the composite materials were studied, and the mechanisms of release were analyzed using different theoretical models. The antibacterial activity against Pseudomonas aeruginosa was evaluated for both the polymyxin hybrid and the composite delivery systems. All tested samples inhibited bacterial growth. The minimal inhibitory concentrations of the polymyxin B hybrid delivery system demonstrated a synergistic effect when compared with either the antibiotic or the silver nanoparticles alone.

Synthesis and application of PHEMA-b-PMPS copolymers using RAFT polymerization

Poly (2-hydroxyethyl methacrylate)-block-poly (3-(methacryloxy)propyl trimethoxysilane) (PHEMA-b-PMPS) was obtained through the reversible addition–fragmentation chain transfer polymerization (RAFT) and analyzed using 1H NMR, FTIR, GPC and DSC techniques. Under the polymerization condition, the Mw /Mn value of the well-defined block copolymers was around 1.1–1.2. These silicon-containing polymers possess many applications. First, this amphiphilic block copolymers shown good ability based on its surface tension control performance. Then, the self-assembly behaviors of block copolymer in the mixed solvents were studied. DLS results have shown that the aggregates could self-assemble into core–shell particles. These core–shell structure and resulting hybrid core–shell nanoparticles were analyzed by TEM. Finally, the biocompatibility of the copolymer hydrogels was verified by in vitro cell viability studies on fibroblasts L929.

Synthesis of a magnetic SiO2-HPW12O40@Fe3O4/EN-MIL-101(Cr) catalyst as core-shell nanoparticles and determination of losartan using modified glassy carbon electrode

The synthesis and properties of new hybrid core-shell nanoparticles SiO2-HPW12O40@Fe3O4/EN-MIL-101(Cr) are reported. These hybrid nanomaterials were synthesized by binding of Keggin-type heteropolyacid (HPA) on diamine-activated Fe3O4 magnetic nanoparticles. The present work proposes an electroanalytical method for selective determination of losartan antihypertensive drug (LOS). Under optimal conditions, an electrochemical sensor was performed between the molecules in 0.1 M phosphate buffer (PBS) pH 6.0. Heterogeneous nanocatalysts can be easily separated from the reaction mixture using a magnet and used multiple times. The structure of the synthesized nanocatalyst was determined by various physicochemical techniques such as TEM, SEM, XRD, EDAX, TGA, and AFM.

Functional polymeric core–shell hybrid nanoparticles overcome intestinal barriers and inhibit breast cancer metastasis

Oral delivery of therapeutic agents is complicated by issues associated with nanocarrier transfer in the gastrointestinal tract, such as physical stability, mucus penetration, and cellular uptake and transport. Various functional nanocarriers have been devised but more research is required to assure the desirable physical stability in the intestinal lumen and biology-responsive diffusion in the mucus. Here, we developed nanoparticles coated with microbial-derived sophorolipid assemblies for oral delivery of therapeutic agents, focusing on improved bioavailability and inhibition of breast cancer metastasis. Upon exposure to the intestinal lumen, the nanoparticles resisted changes in the pH and ion content, and retained their size and composition. They exhibited intestinal biologically responsive diffusion in the mucus because of a charge change from negative to nearly neutral, accompanied by a detachment of sophorolipid assemblies. The latter was possibly caused by the high sophorolipid affinity for mucin, which protected the nanoparticles during mucus penetration. The increased stability and enhanced mucus diffusion improved the intracellular uptake of nanoparticles, thus improving the oral bioavailability of the payload. Administration of silibinin and curcumin co-loaded nanoparticles resulted in an improved therapeutic effect of inhibiting breast cancer metastasis, by regulating tumor microenvironment, in 4T1 tumor bearing mice. The nanoparticles modulated epithelial–mesenchymal transition and inhibited angiogenesis. They also increased the infiltration of CD4+ and CD8+ T cells, and downregulated the immunosuppressive regulatory T cells and myeloid-derived suppressor cells in tumors. In conclusion, the novel nanocarriers are a promising oral drug delivery system.

A General Nanocoating Method via Photoinduced Self-Initiation.

Hybrid core-shell nanoparticles play a very significant role in many applications. Here, we report a light-induced oligomer coating on nanoparticles via Norrish type I reaction. The radical species generated via UV irradiation can chemically initiate the photoinitiators, which are then polymerized and deposited on inorganic nanoparticles via heterogeneous nucleation, forming a soft oligomer coating smaller than 40 nm. This coating method is versatile and potentially applicable to many different types of inorganic cores and their assemblies, making it a very useful technique for "freezing" nanoassemblies in solution. Moreover, these oligomer coatings containing radical species can also initiate surface polymerization of both styrenic and acrylic monomers with certain functionalities for different applications such as self-assembly, plasmon tuning, and pH sensing (3.5-4.5).

PNIPAM-immobilized gold-nanoparticles with colorimetric temperature-sensing and reusable temperature-switchable catalysis properties

The temperature-responsive core–shell hybrid nanoparticles PNIPAMs-AuNP have dual-functional applications as colorimetric temperature-sensors and reusable temperature-switchable catalysts.

Synthesis of core-shell hybrid nanoparticles with pH responsive core and silica shell and their surface characterization

Herein, the preparation of pH-sensitive core-shell hybrid nanoparticles is reported. The core, prepared by emulsion polymerization, consisted of a copolymer of polyvinylimidazole (PVIm) and 3-(trimethoxysilyl) propylmethacrylate (TMSPMA). The silica shell, obtained by sol-gel synthesis, was anchored to the core at the TMSPMA moiety via silane linking. The pH response and the size of the nanoparticles were tuned by adjusting the quantity of VIm. The shell in the particles helps to decrease the drug release around tumoral pH (6.5–7.2).

A Metal-on-Metal Growth Approach to Metal–Metal Oxide Core–Shell Nanostructures with Plasmonic Properties

Hybrid core–shell nanoparticles integrate the material properties from individual components; however, the synthesis of core–shell nanoparticles with dissimilar materials remains challenging. In th...

In Situ Enhanced Raman and Photoluminescence of Bio-Hybrid Ag/Polymer Nanoparticles by Localized Surface Plasmon for Highly Sensitive DNA Sensors

We experimentally demonstrate the simultaneous enhancement of Raman and photoluminescence (PL) of core-shell hybrid nanoparticles consisting of Ag (core) and polydiacetylene (PDA, shell) through the assistance of localized surface plasmon (LSP) effect for the effective biosensor. Core-shell nanoparticles (NPs) are fabricated in deionized water through a sequential process of reprecipitation and self-assembly. The Raman signal of PDA on core-shell NPs is enhanced more than 100 times. Also, highly enhanced photoluminescence is observed on Ag/PDA hybrid NPs after coupling of the complementary t-DNA with p-DNA which are immobilized on PDA shell. This indicates that the core Ag affects the Raman and PL of PDA through the LSP resonance, which can be caused by the energy and/or charge transfer caused by the LSP coupling and the strong electromagnetic field near Ag NP surface. Only electrons present on the surface interact with the PDA shell, not involving the electrically neutral part of the electrons inside the Ag NP. Furthermore, this work shows that as prepared Ag/PDA NPs functionalized by probe DNA can sense the target DNA with an attomolar concentration (100 attomole).

Temperature-Responsive Poly(N-Isopropylacrylamide) Nanogels: The Role of Hollow Cavities and Different Shell Cross-Linking Densities on Doxorubicin Loading and Release.

Smart polymers with extraordinary characteristics are studied in drug-delivery applications. In the current study, temperature-responsive hybrid core-shell nanoparticles were synthesized by precipitation polymerization of N-isopropylacrylamide and vinyl-modified silica nanoparticles. These temperature-responsive hybrid core-shells were prepared with different cross-linking densities by using 2, 4, and 8 mol % of N,N-methylene bisacrylamide (MBA). Hydrolysis of the silica cores of the hybrid core-shells resulted in hollow poly(N-isopropylacrylamide) (PNIPAM) nanogels. Functionalization of silica nanoparticles with vinyl-containing silane modifier of 3-(trimethoxysilyl) propyl methacrylate (MPS) in two different contents was proven by Fourier transform infrared spectroscopy. Preparation of the hybrid PNIPAM nanogels and etching of the silica cores were studied using thermogravimetric analysis and also electron microscopy imaging. Sensitivity of the PNIPAM nanogel samples to temperature was studied using ultraviolet-visible (UV-vis) spectroscopy. In addition, dynamic light scattering was used for investigation of the squeezing and expansion of the hybrid and hollow samples against variation of temperature. The UV-vis spectroscopy results display higher absorption intensities in higher contents of MPS modifier and MBA cross-linker. The swelling content of the nanogels with hollow cavities was higher than that of the hybrid samples. The hybrid nanogels with 2 and 8 wt % silica content and different cross-linking densities and also their hollow nanoparticles were used for loading and release of doxorubicin (DOX). The release characteristics of the DOX-loaded nanogels were studied at different temperatures using UV-vis spectroscopy. The DOX release was higher at temperatures lower than the gel collapse temperature of the PNIPAM network. Although the nanogels with hollow cavities displayed higher loading capacities, the release percentage was higher for the hybrid PNIPAM nanogels, which was confirmed by the experimental release profiles and mathematical models. The most appropriate fitting of the DOX release data from the PNIPAM nanogel samples was observed for the Korsmeyer-Peppas model. Cytotoxicity studies on HeLa cell line showed that drug-loaded hollow samples showed higher toxicity due to loading of a higher amount of DOX.

Mn(ii) chelate-coated superparamagnetic iron oxide nanocrystals as high-efficiency magnetic resonance imaging contrast agents.

In this communication, a paramagnetic bifunctional manganese(ii) chelate ([Mn(Dopa-EDTA)]2−) containing a catechol group is designed and synthesized. The catechol can bind iron ions on the surface of superparamagnetic iron oxide (SPIO) nanocrystals to form core–shell nanoparticles. Both 4 and 7 nm SPIO@[Mn(Dopa-EDTA)]2− show good water solubility, single-crystal dispersion, and low cytotoxicity. The study of the interplay between the longitudinal and transverse relaxation revealed that 4 nm SPIO@[Mn(Dopa-EDTA)]2− with lower r2/r1 = 1.75 at 0.5 T tends to be a perfect T1 contrast agent while 7 nm SPIO@[Mn(Dopa-EDTA)]2− with a higher r2/r1 = 15.0 at 3.0 T tends to be a T2 contrast agent. Interestingly, 4 nm SPIO@[Mn(Dopa-EDTA)]2− with an intermediate value of r2/r1 = 5.26 at 3.0 T could act as T1–T2 dual-modal contrast agent. In vivo imaging with the 4 nm SPIO@[Mn(Dopa-EDTA)]2− nanoparticle shows unique imaging features: (1) long-acting vascular imaging and different signal intensity changes between the liver parenchyma and blood vessels with the CEMRA sequence; (2) the synergistic contrast enhancement of hepatic imaging with the T1WI and T2WI sequence. In summary, these Fe/Mn hybrid core–shell nanoparticles, with their ease of synthesis, good biocompatibility, and synergistic contrast enhancement ability, may provide a useful method for tissue and vascular MR imaging.

Core–shell metal–organic frameworks and hierarchical host–guest structures toward water-stable luminescence of lanthanide complexes in encoding beads

Hetero-MOF domains in hybrid core–shell nanoparticles realize encapsulation and protection of lanthanide complexes for water-stable photoluminescence, facilitating hierarchical encoding beads with a 3D host–guest structure.