Multifunctional Core@Shell Magnetic Nanoprobes for Enhancing Targeted Magnetic Resonance Imaging and Fluorescent Labeling in Vitro and in Vivo

Physicochemical Changes of Apoferritin Protein during Biodegradation of Magnetic Metal Oxide Nanoparticles

The biodegradation of therapeutic magnetic-oxide nanoparticles (MONPs) in the human body raises concerns about their lifespan, functionality, and health risks. Interactions between apoferritin proteins and MONPs in the spleen, liver, and inflammatory macrophages significantly accelerate nanoparticle degradation, releasing metal ions taken up by apoferritin. This can alter the protein's biological structure and properties, potentially causing health hazards. This study examines changes in apoferritin's shape, electrical surface potential (ESP), and protein-core composition after incubation with cobalt-ferrite (CoFe2O4) oxide nanoparticles. Using atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM), we observed changes in the topography and ESP distribution in apoferritin nanofilms over time. After 48 h, the characteristic apoferritin hole (∼1.35 nm) vanished, and the protein's height increased from ∼3.5 to ∼7.5 nm due to hole filling. This resulted in a significant ESP increase on the filled-apoferritin surface, attributed to the formation of a heterogeneous chemical composition and crystal structure (γ-Fe2O3, Fe3O4, CoO, CoOOH, FeOOH, and Co3O4). These changes enhance electrostatic interactions and surface charge between the protein and the AFM tip. This approach aids in predicting and improving the MONP lifespan while reducing their toxicity and preventing apoferritin deformation and dysfunction.

Oxygen self-supplying small size magnetic nanoenzymes for synergistic photodynamic and catalytic therapy of breast cancer

In recent years, tumor catalytic therapy based on nanozymes has attracted widespread attention. However, its application is limited by the tumor hypoxic microenvironment (TME). In this study, we developed oxygen-supplying magnetic bead nanozymes that integrate hemoglobin and encapsulate the photosensitizer curcumin, demonstrating reactive oxygen species (ROS)-induced synergistic breast cancer therapy. Fe3O4 magnetic bead-mediated catalytic dynamic therapy (CDT) generates hydroxyl radicals (˙OH) through the Fenton reaction in the tumor microenvironment. The Hb-encapsulated Fe3O4 magnetic beads can be co-loaded with the photosensitizer/chemotherapeutic agent curcumin (cur), resulting in Fe3O4-Hb@cur. Under hypoxic conditions, oxygen molecules are released from Fe3O4-Hb@cur to overcome the TME hypoxia, resulting in comprehensive effects favoring anti-tumor responses. Upon near-infrared (NIR) irradiation, Fe3O4-Hb@cur activates the surrounding molecular oxygen to generate a certain amount of singlet oxygen (1O2), which is utilized for photodynamic therapy (PDT) in cancer treatment. Meanwhile, we validated that the O2 carried by Hb significantly enhances the intracellular ROS level, intensifying the catalytic therapy mediated by Fe3O4 magnetic beads and inflicting lethal damage to cancer cells, effectively inhibiting tumor growth. Therefore, significant in vivo synergistic therapeutic effects can be achieved through catalytic-photodynamic combination therapy.

Design of manganese-based nanomaterials for pharmaceutical and biomedical applications

In the past few years, manganese-based nanostructures have been extensively investigated in the biomedical field particularly to design highly biocompatible theranostics, which can not only act as efficient diagnostic imaging contrast agents but also deliver the drugs to the target sites. The nanoscale size, large surface area-to-volume ratio, availability of cheap precursors, flexibility to synthesize nanostructures with reproducible properties and high yield, and easy scale up are the major reasons for the attraction towards manganese nanostructures. Along with these properties, the nontoxic nature, pH-sensitive degradation, and easy surface functionalization are additional benefits for the use of manganese nanostructures in biomedical and pharmaceutical sciences. Therefore, in this review, we discuss the recent progress made in the synthesis of manganese nanostructures, describe the attempts made to modify their surfaces to impart biocompatibility and stability in biological fluids, and critically discuss their use in magnetic resonance imaging, drug and gene delivery, hyperthermia, photothermal/photodynamic, immunotherapy, biosensing and tumor diagnosis.

The Metal Ion Release of Manganese Ferrite Nanoparticles: Kinetics, Effects on Magnetic Resonance Relaxivities, and Toxicity

Mn²⁺ release is particularly important for biological application of manganese-based nanomaterials. However, the Mn²⁺ release profiles of the manganese ferrite nanoparticles are under clarification. Here, we synthesized 3, 10, and 18 nm manganese ferrite nanoparticles (MFNPs) as model systems to study the Mn²⁺ release behavior, size, and pH-dependent kinetics. The Mn²⁺ release kinetic study showed that the first-order kinetic model was suitable for 3 and 10 nm MFNPs, while the Higuchi model was suitable for 18 nm MFNPs in a neutral PBS buffer (pH 7.4). In an acidic PBS buffer (pH 4.8), the Mn²⁺ release from all sizes of MFNPs follows first-order kinetics, which is possible due to the reaction between MFNPs and H⁺. The influence of Mn²⁺ release was evaluated by comparing the variations of magnetic resonance (MR) relaxation and magnetic properties before and after Mn²⁺ release of MFNPs. The results showed that the saturation magnetization (M_s), longitudinal relaxivity (r₁), and transverse relaxivity (r₂) values declined due to Mn²⁺ release, while the ratio of r₂/r₁ increased slightly, showing that all sizes of MFNPs exhibited the same MR mode as the synthesized MFNPs. More importantly, the release kinetics were employed to estimate the toxicity of the released Mn²⁺ in vivo. The potential toxicity is acceptable for MFNP administration since the calculated amount of Mn²⁺ is in the range of safe doses.

Advances in the Synthesis and Application of Magnetic Ferrite Nanoparticles for Cancer Therapy

Cancer is among the leading causes of mortality globally, with nearly 10 million deaths in 2020. The emergence of nanotechnology has revolutionised treatment strategies in medicine, with rigorous research focusing on designing multi-functional nanoparticles (NPs) that are biocompatible, non-toxic, and target-specific. Iron-oxide-based NPs have been successfully employed in theranostics as imaging agents and drug delivery vehicles for anti-cancer treatment. Substituted iron-oxides (MFe2O4) have emerged as potential nanocarriers due to their unique and attractive properties such as size and magnetic tunability, ease of synthesis, and manipulatable properties. Current research explores their potential use in hyperthermia and as drug delivery vehicles for cancer therapy. Significantly, there are considerations in applying iron-oxide-based NPs for enhanced biocompatibility, biodegradability, colloidal stability, lowered toxicity, and more efficient and targeted delivery. This review covers iron-oxide-based NPs in cancer therapy, focusing on recent research advances in the use of ferrites. Methods for the synthesis of cubic spinel ferrites and the requirements for their considerations as potential nanocarriers in cancer therapy are discussed. The review highlights surface modifications, where functionalisation with specific biomolecules can deliver better efficiency. Finally, the challenges and solutions for the use of ferrites in cancer therapy are summarised.

Synthesis of a Thermal-Responsive Dual-Modal Supramolecular Probe for Magnetic Resonance Imaging and Fluorescence Imaging

Dual-modal imaging can integrate the advantages of different imaging technologies, which could improve the accuracy and efficiency of clinical diagnosis. Herein, a novel amphiphilic thermal-responsive copolymer obtained from three types of monomers, N-isopropyl acrylamide, 2-(acetoacetoxy) ethyl methacrylate, and propargyl methacrylate, by RAFT copolymerization, is reported. It can be grafted with β-cyclodextrin and aggregation-induced emission (AIE) luminogens tetraphenylethylene by click chemistry and Biginelli reaction. The multifunctional supramolecular polymer (P4) can be constructed by host-guest inclusion between the copolymer and the Gd-based contrast agent (CA) modified by adamantane [Ad-(DOTA-Gd)]. And it can form vesicles with a bilayer structure in aqueous which will enhance the AIE and magnetic resonance imaging effects. As fluorescent thermometer, P4 can enter HeLa cells for intracellular fluorescence imaging (FI) and is sensitive to temperature with detection limit value of 1.5 °C. As magnetic resonance CA, P4 exhibits higher relaxation compared to Magnevist, which can prolong the circulation time in vivo. In addition, Gd³⁺ in the polymer can be quickly released from the body by disassembly that reduced the biological toxicity. This work introduces new synthetic ideas for dual-modal probe, which has great potential for clinical diagnostic applications in bioimaging.

Urinary exosomes-based Engineered Nanovectors for Homologously Targeted Chemo-Chemodynamic Prostate Cancer Therapy via abrogating EGFR/AKT/NF-kB/IkB signaling

Multi-functional nanovectors based on exosomes from cancer cell culture supernatants in vitro has been successfully utilized for tumor-specific targeting and immune escape. However, the labor-intensive purification procedures for rich-dose and high-purity homogeneous exosomes without using targeting ligands are still a challenging task. Herein, we developed a nanovector Exo-PMA/Fe-HSA@DOX through cloaked by urinary exosome membrane as a chemo/chemodynamic theranostic nano-platform for targeted homologous prostate cancer therapy which pertain to the abrogation of Epidermal Growth Factor Receptor (EGFR) and its downstream AKT/NF-kB/IkB signaling instead of ERK signaling cascades. Urinary exosomes-based nanovectors own the same urological cancer cell membrane antigen inclusive of E-cadherin, CD 47 and are free from intracellular substance such as Histone 3 and COX Ⅳ. The targeting properties of the homologous cancer cell are well preserved in Exo-PMA/Fe-HSA@DOX nanovectors in high purity. Meanwhile, the nanovectors based on urinary exosomes from prostate patients deeply penetrated into prostate cancer DU145 3D MCTS, and successfully achieve superior synergistic low-dose chemo/chemodynamic performance in vivo. In addition, the blockage of bypassing EGFR/AKT/NF-kB/IkB signaling pathway is greatly enhanced via elevated intracellular PMA/Fe-HSA@DOX nanoparticles (NPs). It is expected that the rich source and high purity of urinary exosomes offer a reliable solution for mass production of such nanovectors in the future. The targeted homologous cancer therapy based on the urinary exosomes from cancer patients exemplifies a novel targeted anticancer scheme with efficient and facile method.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine.

Bioconjugates of versatile β-diketonate-lanthanide complexes as probes for time-gated luminescence and magnetic resonance imaging of cancer cells in vitro and in vivo

Magnetic resonance imaging (MRI) and optical imaging (OI) are attractive for constructing bimodal probes due to their complementary imaging characteristics. The combination of these two techniques could be a useful tool to simultaneously obtain both anatomical and molecular information as well as to significantly improve the accuracy of detection. In this study, we found that β-diketonate-lanthanide complexes, BHHBCB-Ln3+, could covalently bind to proteins to exhibit long-lived and intense luminescence (Ln3+ = Eu3+, τ = 0.52 ms, Φ = 0.40) and remarkably high relaxivity (Ln3+ = Gd3+, r1 = 35.67 mM-1 s-1, r2 = 43.25 mM-1 s-1) with excellent water solubility, stability and biocompatibility. Hence, we conjugated BHHBCB-Ln3+ with a tumor-targetable biomacromolecule, transferrin (Tf), to construct the probes, Tf-BHHBCB-Ln3+, for time-gated luminescence (TGL, Ln3+ = Eu3+) and MR (Ln3+ = Gd3+) imaging of cancerous cells in vitro and in vivo. As expected, the as-prepared probes showed high specificity to bind with the transferrin receptor-overexpressed cancerous cells, to enable the probe molecules to be accumulated in these cells. Using Tf-BHHBCB-Ln3+ as probes, the cultured cancerous cells and the tumors in tumor-bearing mice have been clearly visualized by background-free TGL and in vivo MR imaging. The research outcomes suggested the potential of β-diketonate-lanthanide complexes for use in constructing bimodal TGL/MR imaging bioprobes.

Dextran mediated MnFe2O4/ZnS magnetic fluorescence nanocomposites for controlled self-heating properties

Dextran mediated MnFe2O4/ZnS opto-magnetic nanocomposites with different concentrations of ZnS were competently synthesized adopting the co-precipitation method. The structural, morphological, magnetic, and optical properties of the nanocomposites were exhaustively characterized by XRD, HRTEM, FTIR, VSM techniques, and PL spectroscopy. XRD spectra demonstrate the existence of the cubic spinel phase of MnFe2O4 and the cubic zinc blend phase of ZnS in the nanocomposites. HRTEM images show the average crystallite size ranges of 15-21 nm for MnFe2O4 and 14-45 nm for ZnS. Investigation of the FTIR spectra reveals the incorporation of ZnS nanoparticles on the surface of MnFe2O4 nanoparticles by dint of biocompatible surfactant dextran. The nanocomposites exhibit both magnetic and photoluminescence properties. Photoluminescence analysis confirmed the redshift of the emission peaks owing to the trap states in the ZnS nanocrystals. The room temperature VSM analysis shows that the saturation magnetization and coercivity of MnFe2O4 nanoparticles initially increase then decrease with the increasing concentration of ZnS in the nanocomposite. The induction heating analysis shows that the presence of dextran enhances the self heating properties of the MnFe2O4/ZnS nanocomposites which can also be controlled by tailoring the concentration of the ZnS nanoparticles. These suggest that MnFe2O4/Dex/ZnS is a decent candidate for hyperthermia applications.

Molecular Stereocomplexation for Enhancing the Stability of Nanoparticles Encapsulated in Polymeric Micelles for Magnetic Resonance Imaging

A generalizable approach for improving the stability of polylactide-based (PLA-based) micelles for encapsulating nanoparticles (NPs) is demonstrated, using stereocomplexation between a pair of poly (ethylene glycol)-b-poly(d-lactide)/poly(ethylene glycol)-b-poly(l-lactide) block copolymer blends. Three different superparamagnetic ferrite-based NPs with distinct nanostructures are first prepared by the high-temperature pyrolysis method, including spherical MnFe₂O₄, cubic MnFe₂O₄, and core-shell MnFe₂O₄@Fe₃O₄. The diameters of these NPs are approximately 7-10 nm as revealed by transmission electron microscopy. These hydrophobic NPs can be encapsulated within self-assembled, stereocomplexed PLA (sc-PLA) micelles. All sc-PLA micelle systems loaded with three different NPs exhibit enhanced stability at elevated temperatures (20-60 °C) and with extended storage time (∼96 h) compared with analogous samples without stereocomplex formation, confirmed by dynamic light scattering measurements. The magnetic NP-loaded micelles with mean diameters of approximately 150 nm show both biocompatibility and superparamagnetic property. Under a 1.5 T magnetic field, cubic MnFe₂O₄ (c-MnFe₂O₄)-loaded micelles exhibit an excellent negative contrast enhancement of MR signals (373 mM^-1·s^-1), while core-shell MnFe₂O₄@Fe₃O₄-loaded micelles show a slightly lower signal for MR imaging (275 mM^-1·s^-1). These results suggest the potential of using sc-PLA-based polymer micelles as universal carriers for magnetic resonance imaging contrast agents with improved stability for different applications such as cancer diagnosis.

The vacuolization of macrophages induced by large amounts of inorganic nanoparticle uptake to enhance the immune response

Inorganic nanoparticles (NPs), particularly iron oxide (IO) and gold (Au) NPs, are widely used in a variety of biomedical applications, such as diagnosis and cancer therapy. As an important component of host defense in organisms, macrophages play a crucial role in responding to foreign substances, such as nanoparticles. Thus, it is of utmost importance to understand the nanotoxicity effects on the immune system by investigating the influences of such nanoparticles. In this study, we found that macrophages can take up large amounts of amphiphilic polymer (PMA)-modified Au and IO NPs, which will induce macrophage cell vacuolization and enhance macrophage polarization. This mechanism is an essential part of the immune response in vivo. In addition, we report that smaller-sized nanoparticles (ca. 4 nm) show more significant effects on the macrophage polarization and caused lysosomal damage compared to larger nanoparticles (ca. 14 nm). Moreover, the amount of NP uptake in macrophages decreases upon trapping the PMA with PEG, resulting in reduced vacuolization and a reduced immune response. We hypothesize that vacuoles are formed in large amounts during NP uptake by macrophages, which enhances the immune response and induces macrophages toward M1 polarization. These findings are potentially useful for disease treatment and understanding the immune response when NPs are used in vitro and in vivo.

GdVO4:Eu3+,Bi3+ Nanoparticles as a Contrast Agent for MRI and Luminescence Bioimaging

With the development of multifunctional imaging, gadolinium (Gd)-bearing inorganic nanoparticles (NPs), which were doped with trivalent lanthanide (Ln3+), have been applied in magnetic resonance imaging (MRI) and optical imaging owing to their high payload of Gd3+ ions and specific optical characteristics. In this study, we chose GdVO4 codoped with Eu3+ and Bi3+ as the host material to generate a highly efficient contrast agent (CA) for MRI and long-term luminescence imaging. The new CA emits strong and stable luminescence because of its strong characteristic emissions, resulting from the energy-transfer process from the vanadate groups (VO4 3-) to the Eu3+ and Bi3+ dopants. Additionally, these NPs provided conspicuous T 1 and T 2 relaxation time-shortening characteristics, which result in MRI enhancement. GdVO4:Eu3+,Bi3+ NPs were tested on liver tumor-bearing nude mice, and showed improved liver tumor contrast in T 2-weighted MR images (T 2WI). The dual-modal imaging probe exhibited no cytotoxicity or organ toxicity, reflecting its excellent biocompatibility. Thus, GdVO4:Eu3+,Bi3+ has the potential to be used for bioassays in vitro and liver tumor targeting in vivo. The results reveal the great promise of using the designed GdVO4:Eu3+,Bi3+ NPs as luminescent and MRI dual-mode bioprobes for clinical bioimaging applications.

Multifunctional co-loaded magnetic nanocapsules for enhancing targeted MR imaging and in vivo photodynamic therapy

Drug delivery nanocarriers based on magnetic nanoparticles have attracted increasing attention due to their potential applications in magnetic resonance imaging, photodynamic therapy and targeted drug delivery. Herein, we have fabricated the multifunctional co-loaded magnetic nanocapsules (MNCPs) using a microemulsion process for enhancing targeted magnetic resonance imaging and in vivo photodynamic therapy. MNCPs were synthesized by co-loading Co@Mn magnetic nanoparticles and chlorin e6 into the matrix of an amphiphilic polymer, and further surface covalently coupled with target molecules. This work demonstrates that MNCPs have uniform sizes (d_c: ~150 nm), favorable biocompatibility, long-term stability, excellent T₂ relaxation values, and high drug loading efficiency. These advantages offer MNCPs successfully applied in targeted magnetic resonance imaging, real-time fluorescent labeling, and photodynamic therapy. The research results will contribute to rationally design novel nano-platform and provide a promising approach for further clinical integration of diagnosis and treatment in the near future.

A dual-modal nanoprobe based on Eu(iii) complex-MnO2 nanosheet nanocomposites for time-gated luminescence-magnetic resonance imaging of glutathione in vitro and in vivo

Dual-modal fluorescence-magnetic resonance imaging (MRI) techniques have gained great interest in biomedical research and clinical practice, since they integrate the advantages of both imaging techniques and provide a useful approach to simultaneously investigate both molecular and anatomical information at the same biological structures. Herein, we report the construction of a dual-modal time-gated luminescence (TGL)/MRI nanoprobe, BHHBB-Eu3+@MnO2, for glutathione (GSH) by anchoring luminescent β-diketone-Eu3+ complexes on layered MnO2 nanosheets. The fabricated nanoprobe exhibited very week luminescence and MR signals since the luminescence of the Eu3+ complex was quenched by MnO2 nanosheets and Mn atoms were isolated from water. Upon exposure to GSH, the MnO2 nanosheets were rapidly and selectively reduced to Mn2+ ions, resulting in remarkable enhancements of TGL and MR signals simultaneously. The combination of TGL and MR detection modes enables the nanoprobe to be used for detecting GSH in a wide concentration range (1-1000 μM) and imaging GSH at different resolutions and depths ranging from the subcellular level to the whole body. Furthermore, the as-prepared nanoprobe exhibited a low cytotoxicity and good biocompatibility, rapid response rate, long-lived luminescence, and high sensitivity and selectivity for responding to GSH. These features allowed it to be successfully used for the TGL detection of GSH in human sera, TGL imaging of GSH in living cells and zebrafish, as well as dual-modal TGL/MR imaging of GSH in tumor-bearing mice. All of these results highlighted the applicability and advantages of the nanoprobe for detecting GSH in vitro and in vivo.

Biconcave Carbon Nanodisks for Enhanced Drug Accumulation and Chemo-Photothermal Tumor Therapy

It is considered a significant challenge to construct nanocarriers that have high drug loading capacity and can overcome physiological barriers to deliver efficacious amounts of drugs to solid tumors. Here, the development of a safe, biconcave carbon nanodisk to address this challenge for treating breast cancer is reported. The nanodisk demonstrates fluorescent imaging capability, an exceedingly high loading capacity (947.8 mg g-1 , 94.78 wt%) for doxorubicin (DOX), and pH-responsive drug release. It exhibits a higher uptake rate by tumor cells and greater accumulation in tumors in a mouse model than its carbon nanosphere counterpart. In addition, the nanodisk absorbs and transforms near-infrared (NIR) light to heat, which enables simultaneous NIR-responsive drug release for chemotherapy and generation of thermal energy for tumor cell destruction. Notably, this NIR-activated dual therapy demonstrates a near complete suppression of tumor growth in a mouse model of triple-negative breast cancer when DOX-loaded nanodisks are administered systemically.

Bimodal Phosphorescence-Magnetic Resonance Imaging Nanoprobes for Glutathione Based on MnO2 Nanosheet-Ru(II) Complex Nanoarchitecture

Bimodal fluorescence-magnetic resonance imaging (MRI) technique has shown great utilities in bioassays because it combines the advantages of both optical imaging and MRI to provide more sufficient information over any modality alone. In this work, on the basis of a MnO₂ nanosheet-Ru(II) complex nanoarchitecture, a bimodal phosphorescence-MRI nanoprobe for glutathione (GSH) has been constructed. The nanoprobe, Ru(BPY)₃@MnO₂, was constructed by integrating MnO₂ nanosheets with a phosphorescent Ru(II) complex [Ru(BPY)₃](PF₆)₂ (BPY = 2,2'-bipyridine), which resulted in complete phosphorescence quenching of the Ru(II) complex, accompanied by very low longitudinal and transverse relaxivity. Upon exposure to GSH, the reduction of MnO₂ nanosheets by GSH triggers a recovery of phosphorescence and simultaneously produces a number of Mn²⁺ ions, a perfect MRI contrast agent. The as-prepared nanoprobe showed good water dispersion and biocompatibility and a rapid, selective, and sensitive response toward GSH in the phosphorescence and MR detection modes. The practicability of the nanoprobe was proved by time-gated luminescence assay of GSH in human serum, phosphorescent imaging of endogenous GSH in living cells, zebrafish, and tumor-bearing mice, as well as the MRI of GSH in tumor-bearing mice. The research outcomes suggested the potential of Ru(BPY)₃@MnO₂ for the bimodal phosphorescence-MRI sensing of GSH in vitro and in vivo.

Construction of a multifunctional nanoprobe for tumor-targeted time-gated luminescence and magnetic resonance imaging in vitro and in vivo

A dual-modal fluorescence-magnetic resonance imaging technique has gained tremendous attention for its potential in the dawning era of early diagnosis of tumors with high accuracy. In this study, a facile approach has been developed to prepare a tumor-targetable nanoprobe, PTTA-Eu3+-CoFeO-FA nanoparticles, for dual-modal time-gated luminescence (TGL)-magnetic resonance (MR) imaging of tumor cells in vitro and in vivo. The multifunctional nanoprobe was constructed by coating a tumor-targeting molecule, folic acid (FA), and a luminescent Eu3+ complex, PTTA-Eu3+, onto the surface of cobalt/iron oxide (CoFeO) nanoparticles. The as-prepared PTTA-Eu3+-CoFeO-FA nanoparticles are well dispersed in water with good biocompatibility, strong long-lived luminescence as well as pronounced transverse relaxivity. The in vitro study reveals that the nanoprobe works well as an effective luminescent probe to achieve the targeted TGL imaging of RAW 264.7 cells without the interference of background fluorescence, and the results of in vivo dual-modal TGL-MR imaging indicate that the fabricated nanoprobe can be preferentially accumulated in the tumor to effectively enhance the signals of T2-weighted MR imaging and TGL imaging. The research achievements will contribute to the development of new dual-modal fluorescence-MR nanoprobes for application in clinical diagnosis and therapy of tumors.

A theranostic nanoplatform: magneto-gold@fluorescence polymer nanoparticles for tumor targeting T1&T2-MRI/CT/NIR fluorescence imaging and induction of genuine autophagy mediated chemotherapy

Multifunctional nanoparticles, bearing low toxicity and tumor-targeting properties, coupled with multifunctional diagnostic imaging and enhanced treatment efficacy, have drawn tremendous attention due to their enormous potential for medical applications. Herein, we report a new kind of biocompatible and tumor-targeting magneto-gold@fluorescent polymer nanoparticle (MGFs-LyP-1), which is based on ultra-small magneto-gold (Fe₃O₄-Au) nanoparticles and NIR emissive fluorescent polymers by a solvent-mediated method. This kind of nanoparticle could be taken up efficiently and simultaneously serve for in vivo tumor targeting T₁&T₂-MRI/CT/near infrared (NIR) fluorescence bioimaging. Furthermore, the nanoparticles exhibit small size, higher tumor targeting accumulation, excellent cytocompatibility for long-term tracking, and no disturbing cell proliferation and differentiation. Moreover, clear and convincing evidence proves that as-synthesized MGFs-LyP-1 could elicit genuine autophagy via inducing autophagosome formation, which offers a definite synergistic effect to enhance cancer therapy with doxorubicin (DOX) at a nontoxic concentration through enhancement of the autophagy flux. Meanwhile, the as-prepared nanoparticles could be rapidly cleared from mice without any obvious organ impairment. The results indeed reveal a promising prospect of an MGFs-LyP-1 contrast agent with low toxicity and high efficiency for promising application in biomedicine.

Applications of cobalt ferrite nanoparticles in biomedical nanotechnology

Magnetic nanoparticles (MNPs) are very attractive especially for biomedical applications, among which, iron oxide nanoparticles have received substantial attention in the past decade due to the elemental composition that makes them biocompatible and degradable. However recently, other magnetic nanomaterials such as spinel ferrites that can provide improved magnetic properties such as coercivity and anisotropy without compromising on inherent advantages of iron oxide nanoparticles are being researched for better applicability of MNPs. Among various spinel ferrites, cobalt ferrite (CoFe₂O₄) nanoparticles (NPs) are one of the most explored MNPs. Therefore, the intention of this article is to provide a comprehensive review of CoFe₂O₄ NPs and their inherent properties that make them exceptional candidates, different synthesis methods that influence their properties, and applications of CoFe₂O₄ NPs and their relevant applications that have been considered in biotechnology and bioengineering.

Recent Progress in Synthesis and Functionalization of Multimodal Fluorescent-Magnetic Nanoparticles for Biological Applications

There is a great interest in the development of new nanomaterials for multimodal imaging applications in biology and medicine. Multimodal fluorescent-magnetic based nanomaterials deserve particular attention as they can be used as diagnostic and drug delivery tools, which could facilitate the diagnosis and treatment of cancer and many other diseases. This review focuses on the recent developments of magnetic-fluorescent nanocomposites and their biomedical applications. The recent advances in synthetic strategies and approaches for the preparation of fluorescent-magnetic nanocomposites are presented. The main biomedical uses of multimodal fluorescent-magnetic nanomaterials, including biological imaging, cancer therapy and drug delivery, are discussed, and prospects of this field are outlined.

Porous MnFe2O4-decorated PB nanocomposites: a new theranostic agent for boosted T1/T2 MRI-guided synergistic photothermal/magnetic hyperthermia

This study reports a multifunctional core/shell nanoparticle (NP) that can be used for amplified magnetic resonance image (MRI), enhanced photothermal therapy (PTT) and magnetic hyperthermia therapy (MHT) due to its surface coating with a porous shell. Importantly, by means of introducing the surface coating of a porous shell, it helps entrap large quantities of water around NPs and allow more efficient water exchange, leading to greatly improved MR contrast signals. Besides, the porous shell helps the near-infrared (NIR) absorbance of the core, and then the extremely enhanced thermal effect can be obtained under synergistic combination of PTT and MHT. By synthesizing multifunctional porous MnFe₂O₄/PB as an example, we found that the transversal relaxivity (r₂) of MnFe₂O₄ NPs might improve from 112.11 to 123.46 mM⁻¹ s⁻¹, and the specific absorption rate (SAR) of MnFe₂O₄/PB nanoparticles reached unprecedented levels of up to 4800 W g⁻¹ compared with the SAR 1182 W g⁻¹ of PTT under an 808 nm laser and 180 W g⁻¹ of MHT under an external AC magnetic field. Meanwhile, when MnFe₂O₄ was decorated on PB nanoparticles, the magnetic properties became lower slightly, but the synergistic photothermal/magnetic hyperthermia conversion was enhanced greatly. Subsequently, in vitro T₁–T₂ dual-modal MRI, PTT and MHT results verified that MnFe₂O₄/PB could serve as an excellent MRI/PTT/MHT theranostic agent. Furthermore, the MnFe₂O₄/PB NPs were applied as a T₁–T₂ dual-modal MRI, PTT and MHT theranostic agent for in vivo MRI-guided photothermal and magnetic hyperthermia ablation of tumors by intratumoral injection in 4T1 tumor-bearing mice. The T₁–T₂ dual-modal MR imaging result shows a significantly contrast in the tumor site. The MPB-mediated PTT and MHT result shows high therapeutic efficiency as a result of high photothermal and magnetic hyperthermia conversion efficiency. The multifunctional NPs have a great potential application for future clinical tumorous diagnosis and treatment.

We synthesized a new theranostic agent of porous MnFe₂O₄-decorated PB nanocomposites for boosted T₁/T₂ MRI-guided synergistic photothermal/magnetic hyperthermia.

Fluorescence-guided magnetic nanocarriers for enhanced tumor targeting photodynamic therapy

Fe₃O₄-HA-Ce6 nanotheranostic agents demonstrated specific targeting ability toward cancer cells with subsequent improvement in dual modal MR/NIR imaging and photodynamic therapeutic effects.

Click-Functionalized SERS Nanoprobes with Improved Labeling Efficiency and Capability for Cancer Cell Imaging

Precise identification and detection of cancer cells using nanoparticle probes are critically important for early cancer diagnosis and subsequent therapy. We herein develop novel folate receptor (FR)-targeted surface-enhanced Raman scattering (SERS) nanoprobes for cancer cell imaging based on a click coupling strategy. A Raman-active derivative (5,5'-dithiobis(2-nitrobenzoic acid)-N₃ (DNBA-N₃)) is designed with a disulfide bond for covalently anchoring to the surface of hollow gold nanoparticles (HAuNPs) and a terminal azide group for facilitating highly efficient conjugation with the bioligand. Modification of HAuNPs with DNBA-N₃ yields monolayer coverage of Raman labels absorbed on the nanoparticle surface (HAuNP-DNBA-N₃) and strong SERS signals. HAuNP-DNBA-N₃ can be simply and effectively conjugated with folate bicyclo[6.1.0]nonyne derivatives via a copper-free click reaction. The synthesized nanoprobes (HAuNP-DNBA-folic acid (FA)) exhibit excellent targeted capacities to FR-positive cancer cells relative to FR-negative cells through SERS mappings. The receptor-mediated delivery behaviors are confirmed by comparison with the uptake of HAuNP-DNBA-N₃ and free FA competition experiments. In addition to its good stability and benign biocompatibility, the developed SERS nanoprobes have great potential for applications in targeted tumor imaging.

Large-scale immuno-magnetic cell sorting of T cells based on a self-designed high-throughput system for potential clinical application

In this contribution, we designed four types of immuno-magnetic nanoparticles for separation of different T cells (CD3⁺, CD4⁺, CD8⁺ and CD14⁺ T cells), and we established a new large-scale immuno-magnetic cell sorting procedure to achieve an enrichment of particular T cells using our designed auto-IMACS device. This device could achieve recyclable large-scale cell sorting, for which the throughput of the system reached ∼4000 mL and the maximum cell capacity was 4 × 10¹⁰. The collected cells were analyzed by flow cytometry and visual cytology data, and the effective selection rates of CD3⁺, CD4⁺, CD8⁺ and CD14⁺ T cells were 79.3%, 74.1%, 57.1% and 67.9%, respectively. The sorted CD8⁺ T cells still retained good cytotoxic activity against specific cells. In addition, the sorted T cells can also be further incubated in vitro and proliferated, and even could be infused back into patients for immunotherapy in the near future.