Hybrid Gadolinium Oxide Nanoparticles: Multimodal Contrast Agents for in Vivo Imaging

Analytical strategies for detecting nanoparticle-protein interactions

A significant increase in biomedical applications of nanomaterials and their potential toxicity demands versatile analytical techniques to determine protein-nanoparticle (NP) interactions. These diverse analytical techniques are reviewed. Spectroscopic methods play a significant role in studying binding affinity, binding ratio, and binding mechanisms. To elucidate NP-proteome interactions, chromatography and electrophoresis techniques are applied to separate NP-bound proteins and matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to identify these proteins. Since NP-protein binding is a dynamic event, surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) are methods of choice to study the kinetics of NP-protein binding.

Imaging and quantifying the morphology of an organic-inorganic nanoparticle at the sub-nanometre level

The development of hybrid organic-inorganic nanoparticles is of interest for applications such as drug delivery, DNA and protein recognition, and medical diagnostics. However, the characterization of such nanoparticles remains a significant challenge due to the heterogeneous nature of these particles. Here, we report the direct visualization and quantification of the organic and inorganic components of a lipid-coated silica particle that contains a smaller semiconductor quantum dot. High-angle annular dark-field scanning transmission electron microscopy combined with electron energy loss spectroscopy was used to determine the thickness and chemical signature of molecular coating layers, the element atomic ratios, and the exact positions of different elements in single nanoparticles. Moreover, the lipid ratio and lipid phase segregation were also quantified.

Gadolinium oxide ultranarrow nanorods as multimodal contrast agents for optical and magnetic resonance imaging

We demonstrate a simple synthetic strategy for the fabrication of single-phase rare earth (RE) doped gadolinium oxide (Gd(2)O(3):RE where RE = terbium (Tb), ytterbium (Yb), and erbium (Er)) nanorods (NRs) as multimodal imaging probes. The NRs are ultranarrow and exhibit both emission and magnetic characteristics. The Tb-doped and Yb/Er-codoped Gd(2)O(3) NRs exhibit down- and up-conversion fluorescence respectively, and also exhibit paramagnetism. Importantly, these codoped NRs possess excellent magnetic characteristics, as shown in their longitudinal relaxation time (T1) -weighted image contrast, which is closer to that of commercial Gadovist for magnetic resonance imaging (MRI) applications. This property opens up new avenues in the development of contrast agents.

Magnetic-field-induced optical bistability in multifunctional Gd(2)O(3):Er(3+)Yb(3+) upconversion nanophosphor

The effect of an external magnetic field (0-1 T) on the upconversion emission (lambda(exc)=976 nm) of Gd(2)O(3):Er(3+)Yb(3+) nanocrystalline phosphor has been studied. Optical bistability (hysteresis behavior in the intensity of the optical emission) for different transitions of the Er(3+) ion has been observed for a complete cycle of the magnetic field between 0 and 1 T. The phosphor shows paramagnetic behavior, consistent with the presence of Gd(3+) ions, at room temperature. Interaction between induced magnetization in the Gd(2)O(3) host and the intrinsic magnetic moment of the nanosized clusters of Er(3+) and Yb(3+) ion pairs is proposed to be responsible for the hysteresis behavior.

Facile ligand-exchange with polyvinylpyrrolidone and subsequent silica coating of hydrophobic upconverting beta-NaYF(4):Yb(3+)/Er(3+) nanoparticles

A facile ligand-exchange strategy with a water-soluble polymer, i.e. polyvinylpyrrolidone (PVP), to replace the surface passivating oleate ligands on the beta-NaYF(4) nanoparticle surface is reported. Highly monodisperse oleate-stabilized beta-NaYF(4) nanoparticles were synthesized and the oleates were exchanged with a commercially available PVP allowing the phase transfer of these nanoparticles. The exchanged nanoparticles are readily dispersible in water and other polar solvents. To show the effectiveness of the exchange reaction we used the affinity of the PVP chains to silica and coated the nanoparticles with a uniform, thin silica shell. The PVP exchanged and silica-coated nanoparticles show longer colloidal stability and no surfactant related problems as compared to the reverse microemulsion-based silica-coated nanoparticles, which show a high tendency to aggregate, when removed from the microemulsion. The optical properties of the ligand-exchanged nanoparticles dispersed in water were compared with that of the oleate-stabilized nanoparticles in organic solvents. A decrease in the upconversion emission intensity and a different relative ratio of the green and red upconverted light were observed for the particles dispersed in water after ligand-exchange. PVP is a highly biocompatible polymer and is reported to have a longer blood circulation time and very low accumulation in vital organs, two highly desired properties for in vivo studies. This ligand-exchange strategy opens a new pathway to study the use of beta-NaYF(4) for biological applications in vivo.

Synthesis and characterization of PEGylated Gd2O3 nanoparticles for MRI contrast enhancement

Recently, much attention has been given to the development of biofunctionalized nanoparticles with magnetic properties for novel biomedical imaging. Guided, smart, targeting nanoparticulate magnetic resonance imaging (MRI) contrast agents inducing high MRI signal will be valuable tools for future tissue specific imaging and investigation of molecular and cellular events. In this study, we report a new design of functionalized ultrasmall rare earth based nanoparticles to be used as a positive contrast agent in MRI. The relaxivity is compared to commercially available Gd based chelates. The synthesis, PEGylation, and dialysis of small (3-5 nm) gadolinium oxide (DEG-Gd(2)O(3)) nanoparticles are presented. The chemical and physical properties of the nanomaterial were investigated with Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and dynamic light scattering. Neutrophil activation after exposure to this nanomaterial was studied by means of fluorescence microscopy. The proton relaxation times as a function of dialysis time and functionalization were measured at 1.5 T. A capping procedure introducing stabilizing properties was designed and verified, and the dialysis effects were evaluated. A higher proton relaxivity was obtained for as-synthesized diethylene glycol (DEG)-Gd(2)O(3) nanoparticles compared to commercial Gd-DTPA. A slight decrease of the relaxivity for as-synthesized DEG-Gd(2)O(3) nanoparticles as a function of dialysis time was observed. The results for functionalized nanoparticles showed a considerable relaxivity increase for particles dialyzed extensively with r(1) and r(2) values approximately 4 times the corresponding values for Gd-DTPA. The microscopy study showed that PEGylated nanoparticles do not activate neutrophils in contrast to uncapped Gd(2)O(3). Finally, the nanoparticles are equipped with Rhodamine to show that our PEGylated nanoparticles are available for further coupling chemistry, and thus prepared for targeting purposes. The long term goal is to design a powerful, directed contrast agent for MRI examinations with specific targeting possibilities and with properties inducing local contrast, that is, an extremely high MR signal at the cellular and molecular level.

Seed-mediated synthesis of NaY F4:Y b, Er/NaGdF4 nanocrystals with improved upconversion fluorescence and MR relaxivity

Rational combination of different functional lanthanide materials within a single nanocrystal presents a feasible way to develop a multifunctional nanoplatform for various biomedical applications. The conventional methods of synthesizing and integrating two kinds of material together generally involve laborious procedures, whilst codoping different functional ions inside a single lanthanide nanocrystal usually results in a decrease in both its fluorescence and its magnetic resonance relaxivity. Here, we present a seed-mediated synthetic route to prepare core-shell structured NaY F(4):Y b, Er/NaGdF(4) nanocrystals. Epitaxial growth of a gadolinium layer on an upconversion lanthanide seed not only improves its upconversion fluorescence, but also creates a paramagnetic shell with high magnetic resonance relaxivity. The prepared nanocrystals are uniform in size, stable in water and easy for conjugation after modification, which may have the potential to serve as a versatile imaging tool for smart detection or diagnosis in future biomedical engineering.

Dual-modality in vivo imaging using rare-earth nanocrystals with near-infrared to near-infrared (NIR-to-NIR) upconversion luminescence and magnetic resonance properties

Upconversion luminescence (UCL) imaging is expected to play a significant role in future photoluminescence imaging since it shows advantages of sharp emission lines, long lifetimes, superior photostability and no blinking. To further improve penetration depth, herein, near-infrared to near-infrared (NIR-to-NIR) UCL and magnetic properties were combined into a nanoparticle, and NIR-to-NIR UCL and MRI dual-modal bioimaging in vivo of whole-body animal were developed. Hydrophilic and carboxylic acid-functionalized Tm(3+)/Er(3+)/Yb(3+) co-doped NaGdF(4) upconversion nanophosphors (AA-NPs) were synthesized and showed both NIR-to-visible and NIR-to-NIR luminescence under excitation of 980 nm. Collecting the signal of the upconversion emission from AA-NPs in the visible and NIR range, all UCL imaging of cells, tissues and whole-body animals with different penetration depth showed high contrast. Moreover, AA-NPs showed a high relaxivity of 5.60 s(-1) (mM)(-1) and were successfully applied as contrast agents for magnetic resonance imaging (MRI) in vivo. By means of the combination of UCL imaging and MRI, the distribution of AA-NPs in living animals was studied, and the results indicated that these particles mainly accumulate in the liver and spleen without undesirable stay in the lungs. Therefore, the concept of UCL and MR dual-modality imaging in vivo of whole-body animals using Tm(3+)/Er(3+)/Yb(3+) co-doped NaGdF(4) with NIR-to-NIR upconversion luminescent and magnetic resonance properties can serve as a platform technology for the next-generation of probes for bioimaging in vivo.

Polymer-modified gadolinium metal-organic framework nanoparticles used as multifunctional nanomedicines for the targeted imaging and treatment of cancer

Novel nanoscale theragnostic devices were successfully prepared through attachment of well defined, multifunctional polymer chains to gadolinium (Gd) metal-organic framework (MOF) nanoparticles. Copolymers of poly(N-isopropylacrylamide)-co-poly(N-acryloxysuccinimide)-co-poly(fluorescein O-methacrylate) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. The succinimide functionality was utilized as a scaffold for attachment of both a therapeutic agent, such as methotrexate, and a targeting ligand, such as H-glycine-arginine-glycine-aspartate-serine-NH(2) peptide. Employment of a trithiocarbonate RAFT agent allowed for reduction of the polymer end groups to thiolates providing a means of copolymer attachment through vacant orbitals on the Gd(3+) ions at the surface of the Gd MOF nanoparticles. These versatile, nanoscale scaffolds were shown to be biocompatible and have cancer cell targeting, bimodal imaging, and disease treatment capabilities. This unique method provided a simple yet versatile route of producing polymer-nanoparticle theragnostic materials with an unprecedented degree of flexibility in the construct, potentially allowing for tunable loading capacities and spatial loading of targeting/treatment agents, while incorporating bimodal imaging capabilities through both magnetic resonance and fluorescence microscopy.

Paramagnetic ultrasmall gadolinium oxide nanoparticles as advanced T1 MRI contrast agent: account for large longitudinal relaxivity, optimal particle diameter, and in vivo T1 MR images

Paramagnetic ultrasmall gadolinium oxide (Gd(2)O(3)) nanoparticles with particle diameters (d) of approximately 1 nm were synthesized by using three kinds of Gd(III) ion precursors and by refluxing each of them in tripropylene glycol under an O(2) flow. A large longitudinal relaxivity (r(1)) of water proton of 9.9 s(-1) mM(-1) was estimated. As a result, high contrast in vivo T(1) MR images of the brain tumor of a rat were observed. This large r(1) is discussed in terms of the huge surface to volume ratio (S/V) of the ultrasmall gadolinium oxide nanoparticles coupled with the cooperative induction of surface Gd(III) ions for the longitudinal relaxation of a water proton. It is found from the d dependence of r(1) that the optimal range of d for the maximal r(1), which may be used as an advanced T(1) MRI contrast agent, is 1-2.5 nm.

Control of the in vivo biodistribution of hybrid nanoparticles with different poly(ethylene glycol) coatings

Fluorescent nanoparticles containing a gadolinium oxide core are very attractive because they are able to combine both imaging (fluorescence imaging, magnetic resonance imaging) and therapy (X-ray therapy and neutron-capture therapy) techniques. The exploitation of these multifunctional particles for in vivo applications requires accurate control of their biodistribution. The postfunctionalization of these particles by four different poly(ethylene glycol) derivatives, which differ by chain length and end group, exerts a great influence on the zeta potential of the nanoparticles and on their biodistribution after intravenous injection to HEK-beta3-tumor-bearing mice. This study reveals that the behavior of PEGylated nanoparticles, which was monitored by in vivo fluorescence imaging, depends on both the chain length and the end group of the PEG chain.

Tuning the magnetic resonance imaging properties of positive contrast agent nanoparticles by surface modification with RAFT polymers

A novel surface modification technique was employed to produce a polymer modified positive contrast agent nanoparticle through attachment of well-defined homopolymers synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. A range of RAFT homopolymers including poly[N-(2-hydroxypropyl)methacrylamide], poly(N-isopropylacrylamide), polystyrene, poly(2-(dimethylamino)ethyl acrylate), poly(((poly)ethylene glycol) methyl ether acrylate), and poly(acrylic acid) were synthesized and subsequently used to modify the surface of gadolinium (Gd) metal-organic framework (MOF) nanoparticles. Employment of a trithiocarbonate RAFT agent allowed for reduction of the polymer end groups under basic conditions to thiolates, providing a means of homopolymer attachment through vacant orbitals on the Gd3+ ions at the surface of the Gd MOF nanoparticles. Magnetic resonance imaging (MRI) confirmed the relaxivity rates of these novel polymer modified structures were easily tuned by changes in the molecular weight and chemical structures of the polymers. When a hydrophilic polymer was used for modification of the Gd MOF nanoparticles, an increase in molecular weight of the polymer provided a respective increase in the longitudinal relaxivity. These relaxivity values were significantly higher than both the unmodified Gd MOF nanoparticles and the clinically employed contrast agents, Magnevist and Multihance, which confirmed the construct's ability to be utilized as a positive contrast nanoparticle agent in MRI. Further characterization confirmed that increased hydrophobicity of the polymer coating on the Gd MOF nanoparticles yielded minimal changes in the longitudinal relaxivity properties but large increases in the transverse relaxivity properties in the MRI.

In quest of a systematic framework for unifying and defining nanoscience

This article proposes a systematic framework for unifying and defining nanoscience based on historic first principles and step logic that led to a "central paradigm" (i.e., unifying framework) for traditional elemental/small-molecule chemistry. As such, a Nanomaterials classification roadmap is proposed, which divides all nanomatter into Category I: discrete, well-defined and Category II: statistical, undefined nanoparticles. We consider only Category I, well-defined nanoparticles which are >90% monodisperse as a function of Critical Nanoscale Design Parameters (CNDPs) defined according to: (a) size, (b) shape, (c) surface chemistry, (d) flexibility, and (e) elemental composition. Classified as either hard (H) (i.e., inorganic-based) or soft (S) (i.e., organic-based) categories, these nanoparticles were found to manifest pervasive atom mimicry features that included: (1) a dominance of zero-dimensional (0D) core-shell nanoarchitectures, (2) the ability to self-assemble or chemically bond as discrete, quantized nanounits, and (3) exhibited well-defined nanoscale valencies and stoichiometries reminiscent of atom-based elements. These discrete nanoparticle categories are referred to as hard or soft particle nanoelements. Many examples describing chemical bonding/assembly of these nanoelements have been reported in the literature. We refer to these hard:hard (H-n:H-n), soft:soft (S-n:S-n), or hard:soft (H-n:S-n) nanoelement combinations as nanocompounds. Due to their quantized features, many nanoelement and nanocompound categories are reported to exhibit well-defined nanoperiodic property patterns. These periodic property patterns are dependent on their quantized nanofeatures (CNDPs) and dramatically influence intrinsic physicochemical properties (i.e., melting points, reactivity/self-assembly, sterics, and nanoencapsulation), as well as important functional/performance properties (i.e., magnetic, photonic, electronic, and toxicologic properties). We propose this perspective as a modest first step toward more clearly defining synthetic nanochemistry as well as providing a systematic framework for unifying nanoscience. With further progress, one should anticipate the evolution of future nanoperiodic table(s) suitable for predicting important risk/benefit boundaries in the field of nanoscience. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11051-009-9632-z) contains supplementary material, which is available to authorized users.

Polymeric nanomedicine for cancer MR imaging and drug delivery

Multifunctional nanomedicine is emerging as a highly integrated platform that allows for molecular diagnosis, targeted drug delivery, and simultaneous monitoring and treatment of cancer. Advances in polymer and materials science are critical for the successful development of these multi-component nanocomposites in one particulate system with such a small size confinement (<200 nm). Currently, several nanoscopic therapeutic and diagnostic systems have been translated into clinical practice. In this feature article, we will provide an up-to-date review on the development and biomedical applications of nanocomposite materials for cancer diagnosis and therapy. An overview of each functional component, i.e. polymer carriers, MR imaging agents, and therapeutic drugs, will be presented. Integration of different functional components will be illustrated in several highlighted examples to demonstrate the synergy of the multifunctional nanomedicine design.

Magnetic Nanoparticles for Early Detection of Cancer by Magnetic Resonance Imaging

This article provides a brief overview of recent progress in the synthesis and functionalization of magnetic nanoparticles and their applications in the early detection of malignant tumors by magnetic resonance imaging (MRI). The intrinsic low sensitivity of MRI necessitates the use of large quantities of exogenous contrast agents in many imaging studies. Magnetic nanoparticles have recently emerged as highly efficient MRI contrast agents because these nanometer-scale materials can carry high payloads while maintaining the ability to move through physiological systems. Superparamagnetic ferrite nanoparticles (such as iron oxide) provide excellent negative contrast enhancement. Recent refinement of synthetic methodologies has led to ferrite nanoparticles with narrow size distributions and high crystallinity. Target-specific tumor imaging becomes possible through functionalization of ferrite nanoparticles with targeting agents to allow for site-specific accumulation. Nanoparticulate contrast agents capable of positive contrast enhancement have recently been developed in order to overcome the drawbacks of negative contrast enhancement afforded by ferrite nanoparticles. These newly developed magnetic nanoparticles have the potential to enable physicians to diagnose cancer at the earliest stage possible and thus can have an enormous impact on more effective cancer treatment.

Drug development in oncology assisted by noninvasive optical imaging

Early and accurate detection of tumors, like the development of targeted treatments, is a major field of research in oncology. The generation of specific vectors, capable of transporting a drug or a contrast agent to the primary tumor site as well as to the remote (micro-) metastasis would be an asset for early diagnosis and cancer therapy. Our goal was to develop new treatments based on the use of tumor-targeted delivery of large biomolecules (DNA, siRNA, peptides, or nanoparticles), able to induce apoptosis while dodging the specific mechanisms developed by tumor cells to resist this programmed cell death. Nonetheless, the insufficient effectiveness of the vectorization systems is still a crucial issue. In this context, we generated new targeting vectors for drug and biomolecules delivery and developed several optical imaging systems for the follow-up and evaluation of these vectorization systems in live mice. Based on our recent work, we present a brief overview of how noninvasive optical imaging in small animals can accelerate the development of targeted therapeutics in oncology.

Nanoparticles of adaptive supramolecular networks self-assembled from nucleotides and lanthanide ions

Amorphous nanoparticles of supramolecular coordination polymer networks are spontaneously self-assembled from nucleotides and lanthanide ions in water. They show intrinsic functions such as energy transfer from nucleobase to lanthanide ions and excellent performance as contrast enhancing agents for magnetic resonance imaging (MRI). Furthermore, adaptive inclusion properties are observed in the self-assembly process: functional materials such as fluorescent dyes, metal nanoparticles, and proteins are facilely encapsulated. Dyes in these nanoparticles fluoresce in high quantum yields with a single exponential decay, indicating that guest molecules are monomerically wrapped in the network. Gold nanoparticles and ferritin were also wrapped by the supramolecular shells. In addition, these nucleotide/lanthanide nanoparticles also serve as scaffolds for immobilizing enzymes. The adaptive nature of present supramolecular nanoparticles provides a versatile platform that can be utilized in a variety of applications ranging from material to biomedical sciences. As examples, biocompatibility and liver-directing characteristics in in vivo tissue localization experiments are demonstrated.

Reversible signal regulation system of 19F NMR by redox reactions using a metal complex as a switching module

We present here the reversible signal regulation of (19)F NMR using the transition metal complex as a switching module. Water-soluble fluorinated dendrimers containing ferrocene were synthesized as a probe, and the signal intensities of (19)F NMR of the probes were monitored by changing the valence state of the ferrocene moiety. By oxidation of the ferrocene moiety, the relaxation of the nearby fluorine atoms was accelerated via the paramagnetic relaxation enhancement, as a result the (19)F NMR signal from the probe was significantly decreased. The reduction of the ferrocenium cation of the probe recovered the signal intensity. Finally, in combination with the difference of the fluorescence quenching ability between ferrocene and ferrocenium cation, we constructed the multimodal (19)F NMR/fluorescence probe based on the redox switching system.

Water-proton relaxivity of hyperbranched polymers carrying TEMPO radicals

High water-soluble hyperbranched poly(styrene) (HPS) polymers carrying stable 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals, HPS-N-TEMPO, HPS-Im-TEMPO, and HPS-Im-(TEMPO)(2), were prepared in ca. 60% introducing yield. HPS-N-TEMPO and HPS-Im-TEMPO were determined to be nearly spherical shapes of the diameter of 2.4 +/- 0.6 and 2.2 +/- 0.6 nm, respectively, by transmission electron microscope (TEM) images. The values of water-proton relaxivity, r(1), at 25 MHz, 0.59 T, and 25 degrees C were 6.0, 5.2, and 14 mM(-1) sec(-1) for HPS-N-TEMPO, HPS-Im-TEMPO, and HPS-Im-(TEMPO)(2), respectively. The spin-lattice relaxation time (T(1))-weighted images in phantom were also observed.

Nanoparticles for optical molecular imaging of atherosclerosis

Molecular imaging contributes to future personalized medicine dedicated to the treatment of cardiovascular disease, the leading cause of mortality in industrialized countries. Endoscope-compatible optical imaging techniques would offer a stand-alone alternative and high spatial resolution validation technique to clinically accepted imaging techniques in the (intravascular) assessment of vulnerable atherosclerotic lesions, which are predisposed to initiate acute clinical events. Efficient optical visualization of molecular epitopes specific for vulnerable atherosclerotic lesions requires targeting of high-quality optical-contrast-enhancing particles. In this review, we provide an overview of both current optical nanoparticles and targeting ligands for optical molecular imaging of atherosclerotic lesions and speculate on their applicability in the clinical setting.

Fluorescent probes for bioimaging applications

Fluorescent probes based on small organic molecules have become indispensable tools in modern biology because they provide dynamic information concerning the localization and quantity of the molecules of interest, without the need of genetic engineering of the sample. In this review, following a brief outline of the principle of fluorescence imaging, we recount some recent achievements in the field of small-molecular fluorescent probes. First, probes for metal cations, including those suitable for two-photon imaging, are introduced. Next, methodologies to visualize proteases are discussed, with special emphasis on activity-based probes for use in vivo. All these probes have been confirmed to be applicable to cellular or in vivo imaging.

Cation exchange in lanthanide fluoride nanoparticles

Cation exchange in lanthanide fluoride nanoparticles is reported. Typically, dispersible LnF(3) nanoparticles were exposed to another lanthanide ion that was roughly 5 times the amount of Ln(3+) in the nanoparticles. Results show that cation exchange of GdF(3) nanoparticles with La(3+) was almost complete in 1 min, and it also happens reversibly although the degree of exchange is not as much as the forward reaction. However, cation exchange with lanthanide ions close to each other, such as GdF(3) with Eu(3+) and NdF(3) with La(3+), did not end up with nearly full exchange, but with a significant amount of the two lanthanides. A relatively small driving force for the cation exchange is suggested by the experimental results, which is also confirmed by calculations based on a thermodynamic cycle. This unprecedented finding in the field of lanthanide-based nanoparticles raises the question whether reported core-shell structures were indeed made and, at the same time, it opens up new pathways to make nanomaterials that cannot be made directly.

Inorganic nanoparticles for predictive oncology of breast cancer

Nanoparticles (NPs) and nanosized objects are being incorporated rapidly into clinical medicine and particularly into the field of medical oncology, including breast cancer. A number of novel methods for breast cancer diagnosis and treatment, which are based on NPs and other nanodevices, are now available for translation into clinical practice. Computer tomography and MRI with iron-based magnetic NPs are promising methods for radiological detection of cancers. Semiconductor fluorescent NPs (quantum dots) are being developed for simultaneous detection and localization of multiple breast cancer biomarkers, enabling the personalization of therapeutic regimens for each patient. Additionally, inorganic NPs can be conjugated with tumor-specific ligands and used for tumor-selective delivery of chemotherapeutic or hormonal agents. NPs bearing tumor-targeted antibodies and oligonucleotides for anticancer gene therapy are a novel and rapidly developing therapeutic approach in oncology. Nab-paclitaxel and liposomal anthracyclines are US FDA-approved NP-based drug-delivery systems that have demonstrated at least equivalent efficacy and decreased toxicity compared with conventional chemotherapeutic agents used in the treatment of breast cancer. This review focuses on recent applications of NPs into predictive oncology of breast cancer with an emphasis placed on the role of inorganic nanosized objects in the diagnosis and treatment of this malignancy.

Multifunctional Magnetic Nanoparticles for Medical Imaging Applications

Magnetic nanoparticles (MNPs) have attracted enormous research attention due to their unique magnetic properties that enable the detection by the non-invasive medical imaging modality-magnetic resonance imaging (MRI). By incorporating advanced features, such as specific targeting, multimodality, therapeutic delivery, the detectability and applicability of MNPs have been dramatically expanded. A delicate design on structure, composition and surface chemistry is essential to achieving desired properties in MNP systems, such as high imaging contrast and chemical stability, non-fouling surface, target specificity and/or multimodality. This article presents the design fundamentals on the development of MNP systems, from discussion of material selection for nanoparticle cores and coatings, strategies for chemical synthesis and surface modification and their merits and limitations, to conjugation of special biomolecules for intended functions, and reviews the recent advances in the field.