Multifunctional low-generation dendrimer-entrapped gold nanoparticles (Au DENPs) were designed and synthesized. The formed Au DENPs modified with an arginine–glycine–aspartic peptide and labeled with 99mTc possess a uniform size distribution, desirable colloidal stability and biocompatibility, and can be used as a promising nanoprobe for targeted SPECT/CT imaging of αvβ3 integrin-expressing tumors.

Design of dendrimer-based nanoarchitectures for enhanced gene delivery still remains a great challenge. Here, we report the design of core–shell tecto dendrimers using a supramolecular assembly approach for enhanced gene delivery applications. Firstly, β-cyclodextrin (CD)-modified generation 5 (G5) poly(amidoamine) (PAMAM) dendrimers (G5-CD) and adamantine (Ad)-modified generation 3 (G3) PAMAM dendrimers (G3-Ad) both having amine termini were synthesized. Through the supramolecular recognition of CD and Ad, G5-CD/Ad-G3 core–shell tecto dendrimers with a G5 core and G3 shell were formed. The formed G5-CD/Ad-G3 core–shell tecto dendrimers with a size of 8.4 nm possess good monodispersity, well-defined three-dimensional structure, and quite low cytotoxicity. Importantly, with the abundant amines on the surface, the core–shell tecto dendrimers are able to transfect the luciferase (Luc) gene with an efficiency 20 times and 170 times higher than the G5-CD and G3-Ad dendrimers, respectively. The higher gene transfection efficiency can also be qualitatively confirmed by transfection of plasmid DNA encoding enhanced green fluorescence protein. Our results suggest that the developed G5-CD/Ad-G3 core–shell tecto dendrimers may be used as a promising vehicle for enhanced gene transfection applications.

Nanoparticles (NPs) have provided new opportunities to diagnose and treat various types of cancers, while it still remains a great challenge to develop novel and effective nanoscale platforms for these applications. In this study, we report a facile hydrothermal route to generate size- and shape-controlled gadolinium hydroxide (Gd(OH)3) NPs and polyethylenimine (PEI)-stabilized Gd(OH)3@Au core/shell nanostars (NSs). We show that Gd(OH)3 NPs with controlled size and shape can be synthesized through varying the stabilizer, reaction time and solvent. The formed Gd(OH)3 nanorods can be transformed into rice-shaped counterparts in the presence of trisodium citrate dehydrate. Furthermore, the introduction of PEI does not alter the morphology, rather have an impact on the size of the products. This facile synthetic route can also be utilized to synthesize Gd(OH)3@Au nanocomposite particles that can act as seeds to form Gd(OH)3@Au NSs in the Au growth solution. Further modification of PEI endows these NSs with excellent water-solubility and colloidal stability. Due to the strong surface plasmon resonance peak in the near-infrared region, the as-prepared Gd(OH)3@Au-PEI NSs display a high photothermal conversion efficiency under laser irradiation. The developed size- and shape-controlled Gd(OH)3 NPs and PEI-stabilized Gd(OH)3@Au core/shell NSs may be further developed as theranostic agents for various biomedical applications.

The combination of chemotherapy and photothermal therapy (PTT) in multifunctional nanoplatforms to improve cancer therapeutic efficacy is of great significance while it still remains to be a challenging task. Herein, we report Au nanostar (NS)-coated hollow mesoporous silica nanocapsules (HMSs) with surface modified by arginine-glycine-aspartic acid (RGD) peptide as a drug delivery system to encapsulate doxorubicin (DOX) for targeted chemotherapy and PTT of tumors. Au NSs-coated HMSs core/shell nanocapsules (HMSs@Au NSs) synthesized previously were conjugated with RGD peptide via a spacer of polyethylene glycol (PEG). We show that the prepared HMSs@Au-PEG-RGD NSs are non-cytotxic in the given concentration range, and have a DOX encapsulation efficiency of 98.6 ± 0.7%. The designed HMSs@Au-PEG-RGD NSs/DOX system can release DOX in a pH/NIR laser dual-responsive manner. Importantly, the formed HMSs@Au-PEG-RGD NSs/DOX nanoplatform can specifically target cancer cells overexpressing αvβ3 intergrin and exert combination chemotherapy and PTT efficacy to the cells in vitro and a xenografted tumor model in vivo. Our results suggest that the designed HMSs@Au-PEG-RGD NSs/DOX nanoplatform may be used for combination chemotherapy and PTT of tumors.Statement of SignificanceWe demonstrate a convenient approach to preparing a novel RGD-targeted drug delivery system of HMSs@Au-PEG-RGD NSs/DOX that possesses pH/NIR laser dual-responsive drug delivery performance for combinational chemotherapy and PTT of tumors. The developed Au NS-coated HMS capsules have both merits of HMS capsules that can be used for high payload drug loading and Au NSs that have NIR laser-induced photothermal conversion efficiency (70.8%) and can be used for PTT of tumors.Download high-res image (128KB)Download full-size image

•Aqueous-phase synthesized Fe3O4 NPs via coprecipitation, hydrothermal reaction and mild reduction are introduced.•Some key strategies to improve the r2 relaxivity of Fe3O4 NPs and enhance their cellular uptake are discussed in detail.•Fe3O4 NPs can be developed for multi-mode imaging and photothermal therapy of cancer.The design and development of multifunctional nanoplatforms for biomedical applications still remains to be challenging. This review reports the recent advances in aqueous-phase synthesis of iron oxide nanoparticles (Fe3O4 NPs) and their composites for magnetic resonance (MR) imaging and photothermal therapy of cancer. Water dispersible and colloidally stable Fe3O4 NPs synthesized via controlled coprecipitation route, hydrothermal route and mild reduction route are introduced. Some of key strategies to improve the r2 relaxivity of Fe3O4 NPs and to enhance their uptake by cancer cells are discussed in detail. These aqueous-phase synthetic methods can also be applied to prepare Fe3O4 NP-based composites for dual-mode molecular imaging applications. More interestingly, aqueous-phase synthesized Fe3O4 NPs are able to be fabricated as multifunctional theranostic agents for multi-mode imaging and photothermal therapy of cancer. This review will provide some meaningful information for the design and development of various Fe3O4 NP-based multifunctional nanoplatforms for cancer diagnosis and therapy.Download high-res image (87KB)Download full-size image

Development of cost-effective and highly efficient nanoprobes for targeted tumor single-photon emission computed tomography (SPECT)/computed tomography (CT) dual-mode imaging remains a challenging task. Here, multifunctional dendrimer-entrapped gold nanoparticles (Au DENPs) modified with folic acid (FA) and labeled with 99mTc were synthesized for targeted dual-mode SPECT/CT imaging of tumors. Generation 2 (G2) poly(amidoamine) (PAMAM) dendrimers (G2-NH2) conjugated with cyclic diethylenetriamine pentaacetic anhydride (cDTPAA) via an amide linkage and FA via a spacer of polyethylene glycol (PEG) were used for templated synthesis of Au core NPs, followed by labeling of 99mTc via chelation. The thus created multifunctional Au DENPs were well-characterized. It is shown that particles with an average Au core diameter of 1.6 nm can be dispersed in water, display stability under different conditions, and are cytocompatible in the studied concentration range. Further results demonstrate that the multifunctional nanoprobe is able to be utilized for targeted SPECT/CT dual-mode imaging of cancer cells having FA receptor (FAR)-overexpression in vitro and the established subcutaneous tumor model in vivo within a time frame up to 4 h. The formed multifunctional Au DENPs synthesized using dendrimers of low-generation may be employed as an effective and economic nanoprobe for SPECT/CT imaging of different types of FAR-expressing tumors.Keywords: dendrimers; folic acid targeting; gold nanoparticles; SPECT/CT imaging; tumors

We report a facile approach to synthesizing hyaluronic acid (HA)-modified Fe3O4@Mn3O4 nanocomposites (NCs) for targeted T1/T2 dual-mode magnetic resonance (MR) imaging of cancer cells. In this work, branched polyethyleneimine (PEI)-coated Fe3O4@Mn3O4 NCs (Fe3O4@Mn3O4-PEI NCs) were first synthesized via a one-pot hydrothermal route, followed by modification of HA on the particle surface via PEI amines. The formed Fe3O4@Mn3O4-PEI-HA NCs were well characterized via different techniques. Our results manifest that the formed Fe3O4@Mn3O4-PEI-HA NCs possess good water dispersibility, colloidal stability, cytocompatibility in the studied concentration range, and targeting specificity to CD44 receptor-overexpressing cancer cells. Due to the coexistence of Fe3O4 and Mn3O4 in the particles, the Fe3O4@Mn3O4-PEI-HA NCs display relatively high r2 (143.26 mM−1 s−1) and r1 (2.15 mM−1 s−1) relaxivities, and can be used as an efficient nanoprobe for targeted T1/T2 dual-mode MR imaging of cancer cells in vitro. The developed Fe3O4@Mn3O4-PEI-HA NCs may hold great promise to be used as a nanoplatform for theranostics of different biological systems.

We report a convenient approach to prepare ultrasmall Fe3O4 nanoparticles (NPs) functionalized with an arginylglycylaspartic acid (RGD) peptide for in vitro and in vivo magnetic resonance (MR) imaging of gliomas. In our work, stable sodium citrate-stabilized Fe3O4 NPs were prepared by a solvothermal route. Then, the carboxylated Fe3O4 NPs stabilized with sodium citrate were conjugated with polyethylene glycol (PEG)-linked RGD. The formed ultrasmall RGD-functionalized nanoprobe (Fe3O4-PEG-RGD) was fully characterized using different techniques. We show that these Fe3O4-PEG-RGD particles with a size of 2.7 nm are water-dispersible, stable, cytocompatible and hemocompatible in a given concentration range, and display targeting specificity to glioma cells overexpressing αvβ3 integrin in vitro. With the relatively high r1 relaxivity (r1 = 1.4 mM−1 s−1), the Fe3O4-PEG-RGD particles can be used as an efficient nanoprobe for targeted T1-weighted positive MR imaging of glioma cells in vitro and the xenografted tumor model in vivo via an active RGD-mediated targeting pathway. The developed RGD-functionalized Fe3O4 NPs may hold great promise to be used as a nanoprobe for targeted T1-weighted MR imaging of different αvβ3 integrin-overexpressing cancer cells or biological systems.

We present the polyethyleneimine (PEI)-assisted synthesis of folic acid (FA)-functionalized iron oxide (Fe3O4) nanoparticles (NPs) with ultrahigh relaxivity for in vivo targeted tumor magnetic resonance (MR) imaging. In this work, water-dispersible and stable Fe3O4 NPs were synthesized in the presence of PEI via a facile mild reduction approach. The surface PEI coating afforded the formed Fe3O4 NPs with the ability to be functionalized with polyethylene glycol (PEG)-linked FA and fluorescein isothiocyanate (FI). A further acetylation step to neutralize the remaining PEI surface amines gave rise to the formation of multifunctional FA-functionalized Fe3O4 NPs, which were subsequently characterized via different methods. We show that the developed FA-functionalized Fe3O4 NPs have a good water-dispersibility, good colloidal stability, ultrahigh r2 relaxivity (475.92 mM−1 s−1), and good hemocompatibility and cytocompatibility in the studied concentration range. The targeting specificity of the FA-modified Fe3O4 NPs to FA receptor (FAR)-overexpressing HeLa cells (a human cervical carcinoma cell line) was subsequently validated by flow cytometry and confocal microscopy. Significantly, the developed FA-modified Fe3O4 NPs can be used as a nanoprobe for targeted MR imaging of HeLa cells in vitro and the xenografted tumor model in vivo via an active FA-mediated targeting strategy. The developed multifunctional FA-modified Fe3O4 NPs with an ultrahigh r2 relaxivity may be used as an efficient nanoprobe for the targeted MR imaging of various kinds of FAR-overexpressing tumors.

A facile approach to assembling polyethyleneimine (PEI)-entrapped gold nanoparticles (Au PENPs) onto filter paper is reported. In this work, Au PENPs with an Au core size of 3.2 ± 0.8 nm were formed using PEI as a template, followed by adsorption onto filter paper. The formed Au PENP-containing filter paper was characterized by various techniques. We show that the Au PENPs are able to be adsorbed onto filter paper likely due to the microfibrous structure of the paper and the electrostatic interaction between the positively charged Au PENPs and the negatively charged filter paper. Furthermore, we demonstrate that the Au PENP-assembled filter paper displays an excellent catalytic activity and reusability to converting 4-nitrophenol to 4-aminophenol. Such a development of Au PENP-assembled filter paper may be applicable for the immobilization of other metal NPs onto filter paper for various applications in catalysis, sensing, and biomedical sciences.

Development of novel nanomaterial-based contrast agents for targeted computed tomography (CT) imaging of tumors still remains a great challenge. Here we describe a novel approach to fabricating lactobionic acid (LA)-modified dendrimer-entrapped gold nanoparticles (LA-Au DENPs) for in vitro and in vivo targeted CT imaging of human hepatocellular carcinoma. In this study, amine-terminated poly(amidoamine) dendrimers of generation 5 pre-modified with fluorescein isothiocyanate and poly(ethylene glycol)-linked LA were employed as templates to form Au nanoparticles. The remaining dendrimer terminal amines were subjected to an acetylation reaction to form LA-Au DENPs. The prepared LA-Au DENPs were characterized via different methods. Our results reveal that the multifunctional Au DENPs with a Au core size of 2.7 nm have good stability under different pH (5–8) and temperature (4–50 °C) conditions and in different aqueous media, and are noncytotoxic to normal cells but cytotoxic to the targeted hepatocarcinoma cells in the given concentration range. In vitro flow cytometry data show that the LA-Au DENPs can be specifically uptaken by a model hepatocarcinoma cell line overexpressing asialoglycoprotein receptors through an active receptor-mediated targeting pathway. Importantly, the LA-Au DENPs can be used as a highly effective nanoprobe for specific CT imaging of hepatocarcinoma cells in vitro and the xenoplanted tumor model in vivo. The developed LA-Au DENPs with X-ray attenuation property greater than clinically employed iodine-based CT contrast agents hold a great promise to be used as a nanoprobe for targeted CT imaging of human hepatocellular carcinoma.Keywords: CT imaging; dendrimers; gold nanoparticles; hepatocellular carcinoma; lactobionic acid;

We report the facile hydrothermal synthesis and surface functionalization of branched polyethyleneimine (PEI)-coated iron oxide nanoparticles (Fe3O4–PEI NPs) for biomedical applications. In this study, Fe3O4–PEI NPs were synthesized via a one-pot hydrothermal method in the presence of PEI. The formed Fe3O4–PEI NPs with primary amine groups on the surface were able to be further functionalized with polyethylene glycol (PEG), acetic anhydride, and succinic anhydride, respectively. The formed pristine and functionalized Fe3O4–PEI NPs were characterized via different techniques. We showed that the sizes of the Fe3O4–PEI NPs were able to be controlled by varying the mass ratio of Fe(II) salt and PEI. In addition, the formed Fe3O4–PEI NPs with different surface functionalities had good water dispersibility, colloidal stability, and relatively high R2 relaxivity (130–160 1/(mM·s)). Cell viability assay data revealed that the surface PEGylation and acylation of Fe3O4–PEI NPs rendered them with good biocompatibility in the given concentration range, while the pristine aminated Fe3O4–PEI NPs started to display slight toxicity at the concentration of 50 μg/mL. Importantly, macrophage cellular uptake results demonstrated that both PEGylation and acetylation of Fe3O4–PEI NPs were able to significantly reduce the nonspecific macrophage uptake, likely rendering the particles with prolonged circulation time. With the proven hemocompatibility and rich amine conjugation chemistry, the Fe3O4–PEI NPs with different surface functionalities may be applied for various biomedical applications, especially for magnetic resonance imaging and therapy.Keywords: biocompatibility; hydrothermal synthesis; iron oxide nanoparticles; macrophage cellular uptake; polyethyleneimine;

A facile one-pot hydrothermal approach to synthesizing Fe3O4@Au composite nanoparticles (CNPs) for dual-mode magnetic resonance (MR) and computed tomography (CT) imaging applications is reported. In this work, polyethyleneimine (PEI) partially modified with poly(ethylene glycol) monomethyl ether (mPEG) was used as a stabilizer to form gold NPs (mPEG-PEI.NH2-Au NPs) with the assistance of sodium borohydride reduction. The mPEG-PEI.NH2-Au NPs were then mixed with iron(II) salt in a basic aqueous solution followed by treatment under an elevated temperature and pressure. This hydrothermal process led to the formation of Fe3O4@Au-mPEG-PEI.NH2 CNPs. The remaining PEI amine groups were finally acetylated to reduce the surface positive charge of the CNPs. The formed Fe3O4@Au-mPEG-PEI.NHAc (Fe3O4@Au) CNPs were characterized via different techniques. The combined in vitro cell viability assay, cell morphology observation, flow cytometry, and hemolysis assay data show that the formed Fe3O4@Au CNPs are noncytotoxic and hemocompatible in the given concentration range. MR and CT imaging data reveal that the formed Fe3O4@Au CNPs have a relatively high r2 relaxivity (146.07 mM–1 s–1) and good X-ray attenuation property, which enables their uses as contrast agents for MR imaging of mouse liver and CT imaging of rat liver and aorta. The Fe3O4@Au CNPs developed via the facile one-pot approach may have promising potential for the dual-mode MR/CT imaging of different biological systems.Keywords: computed tomography imaging; gold nanoparticles; hydrothermal synthesis; iron oxide nanoparticles; magnetic resonance imaging;

We report a facile approach for fabrication of Fe3O4@Au nanocomposite particles (NCPs) as a dual mode contrast agent for both magnetic resonance (MR) and computed tomography (CT) imaging applications. In this study, Fe3O4 nanoparticles (NPs) prepared by a controlled coprecipitation approach were used as core particles for subsequent electrostatic layer-by-layer (LbL) assembly of poly(γ-glutamic acid) (PGA) and poly(L-lysine) (PLL) to form PGA/PLL/PGA multilayers, followed by assembly with dendrimer-entrapped gold NPs (Au DENPs) formed using amine-terminated generation 5 poly(amidoamine) dendrimers as templates. After crosslinking the multilayered shell of PGA/PLL/PGA/Au DENPs via EDC chemistry, the remaining amine groups of the outermost layer of Au DENPs were acetylated to neutralize the surface charge of the particles. The formed Fe3O4@Au NCPs were well characterized via different techniques. We show that the formed Fe3O4@Au NCPs are colloidally stable, hemocompatible, and biocompatible in the given concentration range (0–100 μg mL−1). The relatively high r2 relaxivity (71.55 mM−1 s−1) and enhanced X-ray attenuation property when compared with either the uncoated Fe3O4 NPs or the Au DENPs afford the developed Fe3O4@Au NCPs with a capacity not only for dual mode CT and MR imaging of cells in vitro, but also for MR imaging of liver and CT imaging of subcutaneous tissue in vivo. With the facile integration of both Fe3O4 NPs and Au DENPs within one particle system via the LbL assembly technique and dendrimer chemistry, it is expected that the fabricated Fe3O4@Au NCPs may be further modified with multifunctionalities for multi-mode imaging of various biological systems.

We report a facile and economic approach to fabricating catalytic active palladium (Pd) nanoparticle (NP)-immobilized electrospun polyethyleneimine (PEI)/polyvinyl alcohol (PVA) nanofibers for catalytic reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)). In this study, PEI/PVA nanofibrous mats were first electrospun from homogeneous mixture solution of PEI and PVA, followed by cross-linking with glutaraldehyde vapor to render the fibers with good water stability. The nanofibrous mats were then alternatively soaked in potassium tetrachloropallidate (K2PdCl4) and sodium borohydride solution, and the PdCl42- anions complexed with the free amine groups of PEI were able to be reduced to form zero-valent Pd NPs. The formed Pd NP-containing PEI/PVA nanofibers were characterized by different techniques. We show that the immobilization of Pd NPs does not significantly change the morphology of the PEI/PVA nanofibers; instead the mechanical durability of the fibers is significantly improved. The formed Pd NPs with a mean diameter of 2.6 nm are quite uniformly distributed within the fibers with a small portion of particles having a denser distribution at the outer surface of the fibers. The catalytic activity and reusability of the fabricated Pd NP-containing fibrous mats were evaluated by transformation of Cr(VI) to Cr(III) in aqueous solution in the presence of a reducing agent. Our results reveal that the Pd NP-containing nanofibrous mats display an excellent catalytic activity and reusability for the reduction of Cr(VI) to Cr(III). The facile approach to fabricating metal NP-immobilized polymer nanofibers with a high surface area to volume ratio, enhanced mechanical durability, and uniform NP distribution may be extended to prepare different NP-immobilized fibrous systems for various applications in catalysis, sensing, environmental sciences, and biomedicine.Keywords: electrospun PEI/PVA nanofibers; environmental remediation; hexavalent chromium reduction; palladium nanoparticles; reusable catalyst;

•Dendrimers with unique properties can used to form multifunctional MIO NPs.•Various synthetic strategies used to form dendrimer-based MIO NPs are summarized.•Dendrimer-based MIO NPs can be used for different biomedical applications.•Outlooks of dendrimer-based MIO NPs for biomedical applications are discussed.Magnetic iron oxide nanoparticles (MIO NPs) bearing different appropriate surface modifications can be prepared using diverse physical and chemical methods. As an ideal macromolecule, dendrimers have attracted considerable attention because of their unique properties, including their three 3D architecture, monodispersity, highly branched macromolecular characteristics, and tunable terminal functionalities. These properties make dendrimers a powerful nanoplatform for the creation of functional organic and/or inorganic hybrid NPs, in particular dendrimer-based MIO NPs. Here, we report on recent advances in the preparation of dendrimer-based MIO NPs for different biomedical applications, such as magnetic resonance (MR) imaging, drug and gene delivery, and protein immobilization.

We present the polyethyleneimine (PEI)-assisted synthesis of folic acid (FA)-functionalized iron oxide (Fe3O4) nanoparticles (NPs) with ultrahigh relaxivity for in vivo targeted tumor magnetic resonance (MR) imaging. In this work, water-dispersible and stable Fe3O4 NPs were synthesized in the presence of PEI via a facile mild reduction approach. The surface PEI coating afforded the formed Fe3O4 NPs with the ability to be functionalized with polyethylene glycol (PEG)-linked FA and fluorescein isothiocyanate (FI). A further acetylation step to neutralize the remaining PEI surface amines gave rise to the formation of multifunctional FA-functionalized Fe3O4 NPs, which were subsequently characterized via different methods. We show that the developed FA-functionalized Fe3O4 NPs have a good water-dispersibility, good colloidal stability, ultrahigh r2 relaxivity (475.92 mM−1 s−1), and good hemocompatibility and cytocompatibility in the studied concentration range. The targeting specificity of the FA-modified Fe3O4 NPs to FA receptor (FAR)-overexpressing HeLa cells (a human cervical carcinoma cell line) was subsequently validated by flow cytometry and confocal microscopy. Significantly, the developed FA-modified Fe3O4 NPs can be used as a nanoprobe for targeted MR imaging of HeLa cells in vitro and the xenografted tumor model in vivo via an active FA-mediated targeting strategy. The developed multifunctional FA-modified Fe3O4 NPs with an ultrahigh r2 relaxivity may be used as an efficient nanoprobe for the targeted MR imaging of various kinds of FAR-overexpressing tumors.

We report a facile approach for fabrication of Fe3O4@Au nanocomposite particles (NCPs) as a dual mode contrast agent for both magnetic resonance (MR) and computed tomography (CT) imaging applications. In this study, Fe3O4 nanoparticles (NPs) prepared by a controlled coprecipitation approach were used as core particles for subsequent electrostatic layer-by-layer (LbL) assembly of poly(γ-glutamic acid) (PGA) and poly(L-lysine) (PLL) to form PGA/PLL/PGA multilayers, followed by assembly with dendrimer-entrapped gold NPs (Au DENPs) formed using amine-terminated generation 5 poly(amidoamine) dendrimers as templates. After crosslinking the multilayered shell of PGA/PLL/PGA/Au DENPs via EDC chemistry, the remaining amine groups of the outermost layer of Au DENPs were acetylated to neutralize the surface charge of the particles. The formed Fe3O4@Au NCPs were well characterized via different techniques. We show that the formed Fe3O4@Au NCPs are colloidally stable, hemocompatible, and biocompatible in the given concentration range (0–100 μg mL−1). The relatively high r2 relaxivity (71.55 mM−1 s−1) and enhanced X-ray attenuation property when compared with either the uncoated Fe3O4 NPs or the Au DENPs afford the developed Fe3O4@Au NCPs with a capacity not only for dual mode CT and MR imaging of cells in vitro, but also for MR imaging of liver and CT imaging of subcutaneous tissue in vivo. With the facile integration of both Fe3O4 NPs and Au DENPs within one particle system via the LbL assembly technique and dendrimer chemistry, it is expected that the fabricated Fe3O4@Au NCPs may be further modified with multifunctionalities for multi-mode imaging of various biological systems.