Core-satellite Nanoparticles Research Articles

Synthesis of Urchin-like Au@TiO2 Nano-Carriers as a Drug-Loading System Toward Cancer Treatment.

In recent years, improving the pharmaceutical properties of drug delivery for anti-cancer treatment has become increasingly important. This is necessary to address challenges related to absorption, distribution, and stability. One potential approach solution is to attach the drug to a carrier system, such as functional noble nanomaterials, in order to improve the control of drug release and stability. Core-satellite nanoparticles (CSN) with an anisotropic morphology have enormous potential for targeted drug delivery and cancer treatment because of their large surface area, exceptional stability, and biocompatibility. We used a simple seed-mediated approach to synthesize urchin-like gold nanoparticles (ULGNPs) with a high aspect ratio and a dense network of 49 nm-sized branches, using seed solution, silver nitrate, and ascorbic acid. The ULGNPs were synthesized without a surfactant and then encapsulated with thin layers of amorphous TiO2 (ULGNPs@TiO2), resulting in an average overall size of 136±15 nm with a 27.5 nm TiO2 layer. Doxorubicin (Dox) was chosen as a model drug to assess the distribution carrier ability of ULGNPs@TiO2 core-satellite nanoparticles. The results showed 86.5% Dox loading and 72.3% release capacity at pH 5.

A dual-mode immunochromatographic sensor with photothermal and surface-enhanced Raman scattering for sensitive detection of aflatoxin B1

Multimodal lateral flow immunoassay has displayed the great potential to improve the flexibility and practicality of point-of-care testing. Herein, this study developed a dual-mode photothermal (PT) and surface-enhanced Raman scattering (SERS) immunochromatographic sensor for sensitive detection of aflatoxin B1 (AFB1). The bifunctional waxberry-like core-satellite nanoparticles loaded with 5,5′-Dithiobis (2-nitrobenzoic acid) (DTNB) were prepared and coupled with antibody to form PT@SERS nanoprobes for qualitative and quantitative detection of AFB1. The photothermal conversion efficiency and SERS enhancement factor of the nanoprobes were 42.11 % and 1.59 × 107, respectively. Under the optimal conditions, the limit of detection of PT assay was 0.033 ng/mL with a linear range of 0.05–10 ng/mL (R2 = 0.997); the limit of detection of SERS assay was 0.0073 ng/mL with a linear range of 0.005–10 ng/mL (R2 = 0.998). The results of the specificity analysis indicated no cross-reactions with the other toxins. The recoveries of the spiked corn and peanut were from 85.39 % to 112.15 % (PT assay) and 80.04 % to 106.57 % (SERS assay), respectively. The assay demonstrated that the developed dual-mode sensor provided a promising option for achieving the rapid detection of AFB1.

Confining the Growth of AgNPs onto Epigallocatechin Gallate-Decorated Zein Nanoparticles for Constructing Potent Protein-Based Antibacterial Nanocomposites.

Sliver nanoparticles (AgNPs) have attracted tremendous interest as an alternative to commercially available antibiotics due to their low microbial resistance and broad-spectrum antimicrobial activity. However, AgNPs are highly reactive and unstable and are susceptible to fast oxidation. Synthesizing stable and efficient AgNPs using green chemistry principles remains a major challenge. To address this issue, we establish a facile route to form AgNP-doped zein nanoparticle core-satellite superstructures with ultralow minimum bactericidal concentration (MBC). In brief, polyphenol surface-functionalization of zein nanoparticles was performed, and the epigallocatechin gallate (EGCG) layer on zein nanoparticles served as a reducing-cum-stabilizing agent. We used EGCG-decorated zein nanoparticles (ZE) as a template to direct the nucleation and growth of AgNPs to develop metallized hybrid nanoparticles (ZE-Ag). The highly monodispersed core-satellite nanoparticles (∼150 nm) decorated with ∼4.9 nm AgNPs were synthesized successfully. The spatial restriction of EGCG by zein nanoparticles confined the nucleation and growth of AgNPs only on the surface of the particles, which prevented the formation of entangled clusters of polyphenols and AgNPs and concomitantly inhibited the coalescence and oxidation of AgNPs. Thus, this strategy improved the effective specific surface area of AgNPs, and as a result, ZE-Ag efficiently killed the indicator bacteria, Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus(MRSA) after 20 min of incubation, with MBCs of 2 and 4 μg/mL, respectively. This situation indicated that as-prepared core-satellite nanoparticles possessed potent short-term sterilization capability. Moreover, the simulated wound infection model also confirmed the promising application of ZE-Ag as an efficient antimicrobial composite. This work provides new insights into the synthesis and emerging application of AgNPs in food preservation, packaging, biomedicine, and catalysis.

A Review of Magnetic Nanoparticle-Based Surface-Enhanced Raman Scattering Substrates for Bioanalysis: Morphology, Function and Detection Application.

Surface-enhanced Raman scattering (SERS) is a kind of popular non-destructive and water-free interference analytical technology with fast response, excellent sensitivity and specificity to trace biotargets in biological samples. Recently, many researches have focused on the preparation of various magnetic nanoparticle-based SERS substrates for developing efficient bioanalytical methods, which greatly improved the selectivity and accuracy of the proposed SERS bioassays. There has been a rapid increase in the number of reports about magnetic SERS substrates in the past decade, and the number of related papers and citations have exceeded 500 and 2000, respectively. Moreover, most of the papers published since 2009 have been dedicated to analytical applications. In the paper, the recent advances in magnetic nanoparticle-based SERS substrates for bioanalysis were reviewed in detail based on their various morphologies, such as magnetic core-shell nanoparticles, magnetic core-satellite nanoparticles and non-spherical magnetic nanoparticles and their different functions, such as separation and enrichment, recognition and SERS tags. Moreover, the typical application progress on magnetic nanoparticle-based SERS substrates for bioanalysis of amino acids and protein, DNA and RNA sequences, cancer cells and related tumor biomarkers, etc., was summarized and introduced. Finally, the future trends and prospective for SERS bioanalysis by magnetic nanoparticle-based substrates were proposed based on the systematical study of typical and latest references. It is expected that this review would provide useful information and clues for the researchers with interest in SERS bioanalysis.

Sequentially responsive size reduction and drug release of core-satellite nanoparticles to enhance tumor penetration and effective tumor suppression

Poor tumor accumulation remains a serious challenge for nanomedicines to achieve ideal antitumor outcomes. The different size preferences for systematic circulation, tumor retention and deep permeation have attracted great attention when designing antineoplastic nano-delivery system. Herein, we developed a nano-system which can shrink its size in tumor microenvironment to achieve better tumor retention and penetration. In this work, the cationic bovine serum albumin-protected, doxorubicin-loaded gold nanoclusters (CAuNC-DOX) and amino-functionalized mesoporous silica nanoparticles (MSN) are connected by Fe2+ and are further coated with hyaluronic acid (HA) to obtain a core-satellite MSN-Fe-CAuNC-DOX@HA nano system (MFADH). When reaching the tumor site, the HA shell, which endows the system with both good biocompatibility and preferable tumor targeting ability, was disintegrated, followed by acid-stimulated release of small-sized pharmacological unit—CAuNC-DOX for further tumor penetration. As demonstrated in both in vitro and in vivo results, MFADH showed excellent antitumor effect, providing a proof of concept for the feasibility of shrinkable nanoplatforms in tumor treatment.

Absorption-Modulated SiO2@Au Core-Satellite Nanoparticles for Highly Sensitive Detection of SARS-CoV-2 Nucleocapsid Protein in Lateral Flow Immunosensors.

The worldwide spread of coronavirus disease 2019 (COVID-19) highlights the need for rapid, simple, and accurate tests to detect various variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The antigen test, based on the lateral flow immunoassay (LFI), is a suitable “first line of defense” test that enables early identification and timely isolation of patients to minimize viral transmission among communities. However, it is generally less accurate than nucleic acid testing, and its sensitivity needs improvement. Here, a novel rapid detection method is designed to sensitively detect SARS-CoV-2 using isolated gold nanoparticle (AuNP)-assembled SiO2 core–satellite nanoparticles (SiO2@Au CSNPs). Well-grown AuNP satellites in the synthesis of SiO2@Au CSNPs significantly enhanced their light absorption, increased the detection sensitivity, and lowered the detection limit by 2 orders of magnitude relative to conventional gold colloids. The proposed system enabled highly sensitive detection of the SARS-CoV-2 nucleocapsid protein with a detection limit of 0.24 pg mL–1 within 20 min. This is the first study to develop a highly sensitive antigen test using the absorption-modulated SiO2@Au CSNPs. Our findings demonstrate the capacity of this platform to serve as an effective sensing strategy for managing pandemic conditions and preventing the spread of viral infections.

Laser Synthesized Core-Satellite Fe-Au Nanoparticles for Multimodal In Vivo Imaging and In Vitro Photothermal Therapy.

Hybrid multimodal nanoparticles, applicable simultaneously to the noninvasive imaging and therapeutic treatment, are highly demanded for clinical use. Here, Fe-Au core-satellite nanoparticles prepared by the method of pulsed laser ablation in liquids were evaluated as dual magnetic resonance imaging (MRI) and computed tomography (CT) contrast agents and as sensitizers for laser-induced hyperthermia of cancer cells. The biocompatibility of Fe-Au nanoparticles was improved by coating with polyacrylic acid, which provided excellent colloidal stability of nanoparticles with highly negative ζ-potential in water (−38 ± 7 mV) and retained hydrodynamic size (88 ± 20 nm) in a physiological environment. The ferromagnetic iron cores offered great contrast in MRI images with r2 = 11.8 ± 0.8 mM−1 s−1 (at 1 T), while Au satellites showed X-ray attenuation in CT. The intravenous injection of nanoparticles enabled clear tumor border visualization in mice. Plasmonic peak in the Fe-Au hybrids had a tail in the near-infrared region (NIR), allowing them to cause hyperthermia under 808 nm laser exposure. Under NIR irradiation Fe-Au particles provided 24.1 °C/W heating and an IC50 value below 32 µg/mL for three different cancer cell lines. Taken together, these results show that laser synthesized Fe-Au core-satellite nanoparticles are excellent theranostic agents with multimodal imaging and photothermal capabilities.

Synthesis of SERS-active core-satellite nanoparticles using heterobifunctional PEG linkers.

Surface-enhanced Raman scattering (SERS) is a sensitive analytical technique capable of magnifying the vibrational intensity of molecules adsorbed onto the surface of metallic nanostructures. Various solution-based SERS-active metallic nanostructures have been designed to generate substantial SERS signal enhancements. However, most of these SERS substrates rely on the chemical aggregation of metallic nanostructures to create strong signals. While this can induce high SERS intensities through plasmonic coupling, most chemically aggregated assemblies suffer from poor signal reproducibility and reduced long-term stability. To overcome these issues, here we report for the first time the synthesis of gold core–satellite nanoparticles (CSNPs) for robust SERS signal generation. The novel CSNP assemblies consist of a 30 nm spherical gold core linked to 18 nm satellite particles via linear heterobifunctional thiol–amine terminated PEG chains. We explore the effects that the varying chain lengths have on SERS hot-spot generation, signal reproducibility and long-term activity. The chain length was varied by using PEGs with different molecular weights (1000 Da, 2000 Da, and 3500 Da). The CSNPs were characterized via UV-Vis spectrophotometry, transmission electron microscopy (TEM), ζ-potential measurements, and lastly SERS measurements. The versatility of the synthesized SERS-active CSNPs was revealed through characterization of optical stability and SERS enhancement at 0, 1, 3, 5, 7 and 14 days.

Plasmonic Si@Au core-satellite nanoparticles prepared by laser-assisted synthesis for photothermal therapy

We describe a laser-assisted methodology for the fabrication of Si@Au core-satellite nanostructures for photothermal therapy applications. The methodology consists in laser ablative synthesis of Si and Au NPs in water/ethanol solutions, followed by a chemical modification of the Si NPs by APTMS and their subsequent decoration by the Au NPs. We show that despite a relatively small size (< 40 nm) the formed core-satellites exhibit a strong plasmonic absorption peak centred around 610 nm and having a large tail over 700 nm overlapping with the first optical window of relative tissue transparency. Being relatively small and exempt of any toxic impurity due to ultraclean laser synthesis, the fabricated nanoparticles promise a major advancement of imaging and phototherapy modalities based on plasmonic properties of nanomatererials.

Gas-phase synthesis of mesoporous films of Ag/C:H:N:O core-satellite nanoparticles for surface-enhanced Raman spectroscopy

Rapid development in the field of detection of biomolecules by surface-enhanced Raman spectroscopy (SERS) is enabled by enormous progress in the nanofabrication that nowadays allows for the tailor-made production of nanomaterials that can serve as effective and reliable SERS-active platforms. Among others, heterogeneous mesoporous coatings constitute an important class of nanomaterials that receives increasing attention. In this study, we investigate the possibility of producing such nanomaterials using a novel, one-step, and fully solvent-free technique. This approach employs the in-flight decoration of gas-phase synthesized C:H:N:O plasma polymer cores with nanometre-sized silver nanoparticles. Such physically produced Ag/C:H:N:O core-satellite nanoparticles upon deposition on a planar substrate spontaneously form mesoporous nanoparticle films with SERS-active Ag nanoparticles evenly distributed on the surface of supporting C:H:N:O cores. As shown, such produced nanomaterials exhibit, due to their structure, the SERS enhancement factor of (1.1 ± 0.2) × 106, i.e., the enhancement factor one order of magnitude higher than the value 1 × 105 typically reported for silver nanostructures prepared by commonly used magnetron sputtering onto planar substrates.

Anisotropic Bimetallic Core-Satellite-Poly(aniline) Nanohybrids for Detection of Autoantibodies.

Bimetallic core-satellite nanoparticles are widely exploited in surface-enhanced Raman scattering (SERS)-based applications due to their enhanced optical properties compared to single-component metallic nanoparticles (MNPs). In addition, anisotropic hybrid nanostructures containing both MNPs and polymeric compartments constitute a new class of functional nanomaterials for photonic applications because they show different functionalities and physicochemical characteristics at two distinct compartments. Herein, synthesis of two kinds of anisotropic bimetallic core-satellite-poly(aniline) nanohybrids (ABCPNs) using small or polymeric ligand-coated gold nanospheres or gold nanorods as seeds is reported. The ABCPNs exhibit enhanced optical properties due to a local electromagnetic field generated in the narrow interparticle gap between core and satellite nanoparticles. Furthermore, a SERS-based quantitative analysis of autoantibodies against cyclic citrullinated peptide using the ABCPNs as SERS nanoprobes for a diagnosis of early rheumatoid arthritis is demonstrated, suggesting that these multifunctional nanostructures will be potential for advanced SERS-based biosensors.

Circulating tumor-cell-targeting Au-nanocage-mediated bimodal phototherapeutic properties enriched by magnetic nanocores

Metastasis resulting from circulating tumor cells (CTCs) is associated with 90% of all cancer mortality. To disrupt cancer dissemination, therapeutic targeting of CTCs by extracorporeal photodynamic therapy (PDT) has emerged; however, it still remains impractical due to its limited therapeutic window. Herein, we developed a photosensitive and magnetic targeted core-satellite nanomedicine (TCSN) to augment the light-induced damage to the targeted cells. The magnetic nanocore (MNC) with multiple iron oxide nanoparticles stabilized using thiolated polyvinyl alcohol can magnetize the CTCs to achieve magnetic enrichment under a magnetic field. Multiple gold nanocage (AuNC) satellites were conjugated on the MNC to facilitate bimodal photothermal therapy and PDT. Adjusting the thiol content in the MNC allows manipulating the AuNC density on TCSNs, which has been found to demonstrate a density-dependent bimodal phototherapeutic effect under laser irradiation at 808 and 940 nm. Moreover, with the immobilization of anti-epithelial cell adhesion molecule (anti-EpCAM), TCSN exhibited an enhanced affinity toward EpCAM-expressing 4T1 cells. We demonstrate that TCSN-labeled 4T1 cells can be isolated and photo-eradicated in a microfluidic channel with a dynamic flow. Our studies showed that TCSN with the complementary properties of MNC and AuNCs can largely augment the therapeutic window by magnetic enrichment and bimodal phototherapy, serving as an advanced extracorporeal strategy to remove CTCs.

In-flight plasma modification of nanoparticles produced by means of gas aggregation sources as an effective route for the synthesis of core-satellite Ag/plasma polymer nanoparticles

Core-satellite nanoparticles (NPs), i.e. nanoparticles with a core decorated by small nanoparticles, have become highly attractive in a wide range of applications that comprises for instance ultra-sensitive bio-sensing, bio-imaging, targeted drug delivery or catalysis. Although many methods had been developed to produce such nanomaterials, some challenges such as high complexity of used protocols or low purity of synthetized nanoparticles, are still faced. In this study we report on the detailed investigation of a novel, fully plasma-based strategy that allows for the fabrication of silver/plasma polymer core-satellite NPs. The studied deposition procedure utilizes in-flight sputter-deposition of silver onto plasma polymer (C:H:N:O) nanoparticles produced by means of a gas aggregation source (GAS). It is shown that the silver atoms generated by magnetron sputtering of a silver target in an auxiliary plasma chamber located in between the output orifice of the GAS and the main deposition chamber are effectively captured by C:H:N:O nanoparticles as they pass through the inoculation zone of the deposition system. This results in the formation of small Ag nano-islands on the surface of C:H:N:O nanoparticles as witnessed by transmission electron microscopy. Furthermore, it is demonstrated that the size and number of silver satellites may be varied by the magnetron current used for the silver sputtering.

Magnetron Sputtering of Polymeric Targets: From Thin Films to Heterogeneous Metal/Plasma Polymer Nanoparticles.

Magnetron sputtering is a well-known technique that is commonly used for the deposition of thin compact films. However, as was shown in the 1990s, when sputtering is performed at pressures high enough to trigger volume nucleation/condensation of the supersaturated vapor generated by the magnetron, various kinds of nanoparticles may also be produced. This finding gave rise to the rapid development of magnetron-based gas aggregation sources. Such systems were successfully used for the production of single material nanoparticles from metals, metal oxides, and plasma polymers. In addition, the growing interest in multi-component heterogeneous nanoparticles has led to the design of novel systems for the gas-phase synthesis of such nanomaterials, including metal/plasma polymer nanoparticles. In this featured article, we briefly summarized the principles of the basis of gas-phase nanoparticles production and highlighted recent progress made in the field of the fabrication of multi-component nanoparticles. We then introduced a gas aggregation source of plasma polymer nanoparticles that utilized radio frequency magnetron sputtering of a polymeric target with an emphasis on the key features of this kind of source. Finally, we presented and discussed three strategies suitable for the generation of metal/plasma polymer multi-core@shell or core-satellite nanoparticles: the use of composite targets, a multi-magnetron approach, and in-flight coating of plasma polymer nanoparticles by metal.

Self-Assembled Au@Fe Core/Satellite Magnetic Nanoparticles for Versatile Biomolecule Functionalization.

Although the functionalization of magnetic nanoparticles (MNPs) with biomolecules has been widely explored for various biological applications, achieving efficient bioconjugations with a wide range of biomolecules through a single, universal, and versatile platform remains a challenge, which may significantly impact their applications' outcomes. Here, we report a novel MNP platform composed of Au@Fe core/satellite nanoparticles (CSNPs) for versatile and efficient bioconjugations. The engineering of the CSNPs is facilely formed through the self-assembly of ultrasmall gold nanoparticles (AuNPs, 2-3 nm in diameter) around MNPs with a polysiloxane-containing polymer coating. The formation of the hybrid magnetic nanostructure is revealed by absorption spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), element analysis using atomic absorption spectroscopy, and vibrating sample magnetometer. The versatility of biomolecule loading to the CSNP is revealed through the bioconjugation of a wide range of relevant biomolecules, including streptavidin, antibodies, peptides, and oligonucleotides. Characterizations including DLS, TEM, lateral flow strip assay, fluorescence assay, giant magnetoresistive nanosensor array, high-performance liquid chromatography, and absorption spectrum are performed to further confirm the efficiency of various bioconjugations to the CSNP. In conclusion, this study demonstrates that the CSNP is a novel MNP-based platform that offers versatile and efficient surface functionalization with various biomolecules.

Construction of Au@Pt core—satellite nanoparticles based on in-situ reduction of polymeric ionic liquid protected gold nanoparticles

A method of in-situ reduction to prepare Au@Pt core-satellite nanoparticles (NPs) is described by using Au NPs coating poly[1-methyl 3-(2-methacryloyloxy propylimidazolium bromine)] (PMMPImB-@-Au NPs) as the template. After electrostatic complex chloroplatinic acid with PMMPImB shell, the composite NP was directly reduced with N2H4 to produce Au@Pt core-satellite NPs. The characterization of composite and core-satellite NPs under different amounts of chloroplatinic acid were studied by DLS, UV-vis absorption spectrum and TEM. The satellite Pt NPs with a small size (~2 nm) dotted around Au core, and the resulting Au@Pt core-satellite NPs showed a red-shift surface plasmon resonance (SPR) and a good dispersion due to effectively electrostatic repulsion providing by the polymeric ionic liquid (PIL) shell. Finally, Au@Pt core-satellite NPs exhibit an enhanced catalytic activity and cycled catalytic capability for the reduction of p-nitrophenol with NaBH4.

PB@Au Core-Satellite Multifunctional Nanotheranostics for Magnetic Resonance and Computed Tomography Imaging in Vivo and Synergetic Photothermal and Radiosensitive Therapy.

To integrate multiple diagnostic and therapeutic strategies on a single particle through simple and effective methods is still challenging for nanotheranostics. Herein, we develop multifunctional nanotheranostic PB@Au core-satellite nanoparticles (CSNPs) based on Prussian blue nanoparticles (PBNPs) and gold nanoparticles (AuNPs), which are two kinds of intrinsic theranostic nanomaterials, for magnetic resonance (MR)-computed tomography (CT) imaging and synergistic photothermal and radiosensitive therapy (PTT-RT). PBNPs as cores enable T1- and T2-weighted MR contrast and strong photothermal effect, while AuNPs as satellites offer CT enhancement and radiosensitization. As revealed by both MR and CT imaging, CSNPs realized efficient tumor localization by passively targeted accumulation after intravenous injection. In vivo studies showed that CSNPs resulted in synergistic PTT-RT action to achieve almost entirely suppression of tumor growth without observable recurrence. Moreover, no obvious systemic toxicity of mice confirmed good biocompatibility of CSNPs. These results raise new possibilities for clinical nanotheranostics with multimodal diagnostic and therapeutic coalescent design.

Plasmonic Ag Core-Satellite Nanostructures with a Tunable Silica-Spaced Nanogap for Surface-Enhanced Raman Scattering.

Plasmonic Ag core-satellite nanostructures were synthesized by utilizing the ultrathin silica shell as a spacer to generate a tunable nanogap between the Ag core and satellites. To synthesize the nanoparticles, Ag nanoparticles (Ag NPs) with a diameter of ∼60 nm were synthesized as cores, on which Raman dyes were adsorbed and then tunable ultrathin silica shells from 2.0 to 6.5 nm were coated, followed by the deposition of Ag NPs as satellites onto the silica surface. The relationships between the SERS signal and the important parameters, including the satellite diameter and the nanogap distance, were studied by experimental methods and theoretical calculations. The maximum SERS intensity of the core-satellite nanoparticles was over 14.6 times stronger than that of the isolated Raman-encoded Ag/PATP@SiO2 NP. The theoretical calculations indicated that the local maximum calculated enhancement factor (EF) of the hot spots with a 2.0 nm nanogap was 9.5 × 10(5). The well-defined Ag core-satellite nanostructures have a high structural uniformity and an anomalously strong electromagnetic enhancement for highly quantitative SERS, leading to a better understanding of hot spot formation and providing new insights into the optimal design and synthesis of the hot SERS nanostructures in a controlled manner.

Transparent SiO2-Ag core-satellite nanoparticle assembled layer for plasmonic-based chemical sensors

We discovered a promising sensing capability of SiO2@Ag core-satellite nanoparticles with respect to organic melamine when they were consolidated into a solid-type thin-film entity. A series of theoretical models were proposed which provided calculation outcomes superior to those of existing models for the localized surface plasmon resonance spectra of the solid-state assemblies. We envisioned not only that such a SiO2@Ag film is a potential candidate for a transparent solid-state optical nanosensor for the detection of organic molecules but also that the resulting plasmonic resonance model facilitates a better understanding of such a solid-state nanosensor used for a number of sensory applications.