Facile one-pot synthesis of Fe3O4@Au composite nanoparticles for dual-mode MR/CT imaging applications

PEI-based functional materials: Fabrication techniques, properties, and biomedical applications

Cationic polymers have recently attracted considerable interest as research breakthroughs for various industrial and biomedical applications. They are particularly interesting due to their highly positive charges, acceptable physicochemical properties, and ability to undergo further modifications, making them attractive candidates for biomedical applications. Polyethyleneimines (PEIs), as the most extensively utilized polymers, are one of the valuable and prominent classes of polycations. Owing to their flexible polymeric chains, broad molecular weight (MW) distribution, and repetitive structural units, their customization for functional composites is more feasible. The specific beneficial attributes of PEIs could be introduced by purposeful functionalization or modification, long service life, biocompatibility, and distinct geometry. Therefore, PEIs have significant potential in biotechnology, medicine, and bioscience. In this review, we present the advances in PEI-based nanomaterials, their transfection efficiency, and their toxicity over the past few years. Furthermore, the potential and suitability of PEIs for various applications are highlighted and discussed in detail. This review aims to inspire readers to investigate innovative approaches for the design and development of next-generation PEI-based nanomaterials possessing cutting-edge functionalities and appealing characteristics.

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.

Polyethyleneimine-Based Drug Delivery Systems for Cancer Theranostics

With the development of nanotechnology, various types of polymer-based drug delivery systems have been designed for biomedical applications. Polymer-based drug delivery systems with desirable biocompatibility can be efficiently delivered to tumor sites with passive or targeted effects and combined with other therapeutic and imaging agents for cancer theranostics. As an effective vehicle for drug and gene delivery, polyethyleneimine (PEI) has been extensively studied due to its rich surface amines and excellent water solubility. In this work, we summarize the surface modifications of PEI to enhance biocompatibility and functionalization. Additionally, the synthesis of PEI-based nanoparticles is discussed. We further review the applications of PEI-based drug delivery systems in cancer treatment, cancer imaging, and cancer theranostics. Finally, we thoroughly consider the outlook and challenges relating to PEI-based drug delivery systems.

Multifunctional plasmonic-magnetic nanoparticles for bioimaging and hyperthermia

Multicompartment nanoparticles have raised great interest for different biomedical applications, thanks to the combined properties of different materials within a single entity. These hybrid systems have opened new avenues toward diagnosis and combination therapies, thus becoming preferred theranostic agents. When hybrid nanoparticles comprise magnetic and plasmonic components, both magnetic and optical properties can be achieved, which are potentially useful for multimodal bioimaging, hyperthermal therapies and magnetically driven selective delivery. Nanostructures comprising iron oxide and gold are usually selected for biomedical applications, as they display size-dependent properties, biocompatibility, and unique physical and chemical characteristics that can be tuned through highly precise synthetic protocols. We provide herein an overview of the most recent synthetic protocols to prepare magnetic-plasmonic nanostructures made of iron oxide and gold, to then highlight the progress made on multifunctional magnetic-plasmonic bioimaging and heating-based therapies. We discuss the advantages and limitations of the various systems in these directions.

Safe magnetic resonance imaging on biocompatible nanoformulations

Magnetic resonance imaging (MRI) holds promise for the early clinical diagnosis of various diseases, but most clinical MR techniques require the use of a contrast medium. Several nanomaterial (NM) mediated contrast agents (CAs) are widely used as T1- and T2-based MR contrast agents for clinical and non-clinical applications. Unfortunately, most NM-based CAs are toxic or non-biocompatible, restricting their practical/clinical applications. Therefore, the development of nontoxic and biocompatible CAs for clinical MRI diagnosis is highly desired. To this end, several biocompatible and biomimetic strategies have been developed to offer long blood circulation time, significant biocompatibility, in vivo biodistribution and high contrast ability for efficient imaging. However, detailed review reports on biocompatible NMs, specifically for MR imaging have not yet been summarized. Thus, in the present review we summarize  various surface coating strategies (such as polymers, proteins, cell membranes, etc.) to achieve biocompatible NPs, providing a detailed discussion of advances and future prospects for safe MRI imaging.

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

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

Radioactive organic semiconducting polymer nanoparticles for multimodal cancer theranostics

Theranostics with integrations of both imaging and therapeutic elements can enable early diagnosis and effective treatment of cancer. Herein, we report the development of radioactive semiconducting polymer nanoparticles (rSPNs) for multimodal cancer theranostics. Such rSPNs constructed through labeling poly(ethylene glycol) (PEG) grafted SPNs with iodine-131 (¹³¹I) exhibit ideal photothermal property, excellent singlet oxygen (¹O₂) generating ability and good radiolabeling stability. Owing to their small particle dimension and PEG surface corona, rSPNs show an effective accumulation into subcutaneous tumors of living mice after systemic administration. The good fluorescence property and stable radiolabeling of rSPNs enable contrast signals for near-infrared (NIR) fluorescence and single photon emission computed tomography (SPECT) dual-model imaging of tumors. Moreover, rSPNs provide combinational action of photothermal therapy (PTT), photodynamic therapy (PDT) and radiotherapy under NIR laser irradiation, resulting in much higher therapeutic efficacy in inhibiting tumor growth and metastasis relative to SPNs-mediated treatment. This study thus offers a multifunctional organic nanosystem for multimodal cancer theranostics.

Multifunctional Iron Oxide Magnetic Nanoparticles for Biomedical Applications: A Review

Due to their good magnetic properties, excellent biocompatibility, and low price, magnetic iron oxide nanoparticles (IONPs) are the most commonly used magnetic nanomaterials and have been extensively explored in biomedical applications. Although magnetic IONPs can be used for a variety of applications in biomedicine, most practical applications require IONP-based platforms that can perform several tasks in parallel. Thus, appropriate engineering and integration of magnetic IONPs with different classes of organic and inorganic materials can produce multifunctional nanoplatforms that can perform several functions simultaneously, allowing their application in a broad spectrum of biomedical fields. This review article summarizes the fabrication of current composite nanoplatforms based on integration of magnetic IONPs with organic dyes, biomolecules (e.g., lipids, DNAs, aptamers, and antibodies), quantum dots, noble metal NPs, and stimuli-responsive polymers. We also highlight the recent technological advances achieved from such integrated multifunctional platforms and their potential use in biomedical applications, including dual-mode imaging for biomolecule detection, targeted drug delivery, photodynamic therapy, chemotherapy, and magnetic hyperthermia therapy.

Extracellular matrix-degrading STING nanoagonists for mild NIR-II photothermal-augmented chemodynamic-immunotherapy

Regulation of stimulator of interferon genes (STING) pathway using agonists can boost antitumor immunity for cancer treatment, while the rapid plasma clearance, limited membrane permeability, and inefficient cytosolic transport of STING agonists greatly compromise their therapeutic efficacy. In this study, we describe an extracellular matrix (ECM)-degrading nanoagonist (dNAc) with second near-infrared (NIR-II) light controlled activation of intracellular STING pathway for mild photothermal-augmented chemodynamic-immunotherapy of breast cancer. The dNAc consists of a thermal-responsive liposome inside loading with ferrous sulfide (FeS₂) nanoparticles as both NIR-II photothermal converters and Fenton catalysts, 2′3′-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) as the STING agonist, and an ECM-degrading enzyme (bromelain) on the liposome surface. Mild heat generated by dNAc upon NIR-II photoirradiation improves Fenton reaction efficacy to kill tumor cells and cause immunogenic cell death (ICD). Meanwhile, the generated heat triggers a controlled release of cGAMP from thermal-responsive liposomes to active STING pathway. The mild photothermal activation of STING pathway combined with ICD promotes anti-tumor immune responses, which leads to improved infiltration of effector T cells into tumor tissues after bromelain-mediated ECM degradation. As a result, after treatment with dNAc upon NIR-II photoactivation, both primary and distant tumors in a murine mouse model are inhibited and the liver and lung metastasis are effectively suppressed. This work presents a photoactivatable system for STING pathway and combinational immunotherapy with improved therapeutic outcome.

Amphiphilic shell nanomagnetic adsorbents for selective and highly efficient capture of low-density lipoprotein from hyperlipidaemia serum

Removal of low-density lipoprotein (LDL) from hyperlipemia patients’ blood represents an effective approach to prevent the progression of atherosclerotic cardiovascular disease. Based on the LDL structural characteristics and intermolecular interactions,...

Synthetic Antiferromagnetic Gold Nanoparticles as Bimodal Contrast Agents in MRI and CT-An Experimental In Vitro and In Vivo Study

The use of multimodal contrast agents can potentially overcome the intrinsic limitations of individual imaging methods. We have validated synthetic antiferromagnetic nanoparticles (SAF-NPs) as bimodal contrast agents for in vitro cell labeling and in vivo cell tracking using magnetic resonance imaging (MRI) and computed tomography (CT). SAF-NP-labeled cells showed high contrast in MRI phantom studies (r₂* = 712 s⁻¹ mM⁻¹), while pelleted cells showed clear contrast enhancement in CT. After intravenous SAF-NP injection, nanoparticles accumulated in the liver and spleen, as visualized in vivo by significant MRI contrast enhancement. Intravenous injection of SAF-NP-labeled cells resulted in cell accumulation in the lungs, which was clearly detectable by using CT but not by using MRI. SAF-NPs proved to be very efficient cell labeling agents for complementary MRI- and CT-based cell tracking. Bimodal monitoring of SAF-NP labeled cells is in particular of interest for applications where the applied imaging methods are not able to visualize the particles and/or cells in all organs.

Recent Advances in Synthesis, Medical Applications and Challenges for Gold-Coated Iron Oxide: Comprehensive Study

Combining iron oxide nanoparticles (Fe3O4 NPs) and gold nanoparticles (Au NPs) in one nanostructure is a promising technique for various applications. Fe3O4 NPs have special supermagnetic attributes that allow them to be applied in different areas, and Au NPs stand out in biomaterials due to their oxidation resistance, chemical stability, and unique optical properties. Recent studies have generally defined the physicochemical properties of nanostructures without concentrating on a particular formation strategy. This detailed review provides a summary of the latest research on the formation strategy and applications of Fe3O4@Au. The diverse methods of synthesis of Fe3O4@Au NPs with different basic organic and inorganic improvements are introduced. The role and applicability of Au coating on the surface of Fe3O4 NPs schemes were explored. The 40 most relevant publications were identified and reviewed. The versatility of combining Fe3O4@Au NPs as an option for medical application is proven in catalysis, hyperthermia, biomedical imaging, drug delivery and protein separation.

Iron Oxide Incorporated Conjugated Polymer Nanoparticles for Simultaneous Use in Magnetic Resonance and Fluorescent Imaging of Brain Tumors

Conjugated polymer nanoparticles (CPNs) have emerged as advanced polymeric nanoplatforms in biomedical applications by virtue of extraordinary properties including high fluorescence brightness, large absorption coefficients of one and two-photons, and excellent photostability and colloidal stability in water and physiological medium. In addition, low cytotoxicity, easy functionalization, and the ability to modify CPN photochemical properties by the incorporation of dopants, convert them into excellent theranostic agents with multifunctionality for imaging and treatment. In this work, CPNs were designed and synthesized by incorporating a metal oxide magnetic core (Fe3O4 and NiFe2O4 nanoparticles, 5 nm) into their matrix during the nanoprecipitation method. This modification allowed the in vivo monitoring of nanoparticles in animal models using magnetic resonance imaging (MRI) and intravital fluorescence, techniques widely used for intracranial tumors evaluation. The modified CPNs were assessed in vivo in glioblastoma (GBM) bearing mice, both heterotopic and orthotopic developed models. Biodistribution studies were performed with MRI acquisitions and fluorescence images up to 24 h after the i.v. nanoparticles administration. The resulting IONP-doped CPNs were biocompatible in GBM tumor cells in vitro with an excellent cell incorporation depending on nanoparticle concentration exposure. IONP-doped CPNs were detected in tumor and excretory organs of the heterotopic GBM model after i.v. and i.t. injection. However, in the orthotopic GBM model, the size of the nanoparticles is probably hindering a higher effect on intratumorally T2-weighted images (T2WI) signals and T2 values. The photodynamic therapy (PDT)-cytotoxicity of CPNs was not either affected by the IONPs incorporation into the nanoparticles.

Recent Advances in Inorganic Nanomaterials Synthesis Using Sonochemistry: A Comprehensive Review on Iron Oxide, Gold and Iron Oxide Coated Gold Nanoparticles

Sonochemistry uses ultrasound to improve or modify chemical reactions. Sonochemistry occurs when the ultrasound causes chemical effects on the reaction system, such as the formation of free radicals, that intensify the reaction. Many studies have investigated the synthesis of nanomaterials by the sonochemical method, but there is still very limited information on the detailed characterization of these physicochemical and morphological nanoparticles. In this comprehensive review, recent advances in the sonochemical synthesis of nanomaterials based on iron oxide nanoparticles (Fe3O4NP), gold nanoparticles (AuNP) and iron oxide-coated gold nanoparticles (Fe3O4@Au NP) are discussed. These materials are the most studied materials for various applications, such as medical and commercial uses. This review will: (1) address the simple processing and observations on the principles of sonochemistry as a starting point for understanding the fundamental mechanisms, (2) summarize and review the most relevant publications and (3) describe the typical shape of the products provided in sonochemistry. All in all, this review's main outcome will provide a comprehensive overview of the available literature knowledge that promotes and encourages future sonochemical work.

Hybrid magnetic nanoparticles as efficient nanoheaters in biomedical applications

Heating at the nanoscale is the basis of several biomedical applications, including magnetic hyperthermia therapies and heat-triggered drug delivery. The combination of multiple inorganic materials in hybrid magnetic nanoparticles provides versatile platforms to achieve an efficient heat delivery upon different external stimuli or to get an optical feedback during the process. However, the successful design and application of these nanomaterials usually require intricate synthesis routes and their magnetic response is still not fully understood. In this review we give an overview of the novel systems reported in the last few years, which have been mostly obtained by organic phase-based synthesis and epitaxial growth processes. Since the heating efficiency of hybrid magnetic nanoparticles often relies on the exchange-interaction between their components, we discuss various interface-phenomena that are responsible for their magnetic properties. Finally, followed by a brief comment on future directions in the field, we outline recent advances on multifunctional nanoparticles that can boost the heating power with light and combine heating and temperature sensing in a single nanomaterial.

Near-infrared light and magnetic field dual-responsive porous silicon-based nanocarriers to overcome multidrug resistance in breast cancer cells with enhanced efficiency

The development of drug delivery systems based on external stimuli-responsive nanocarriers is important to overcome multidrug resistance in breast cancer cells. Herein, iron oxide/gold (Fe3O4/Au) nanoparticles were first fabricated via a simple hydrothermal reaction, and subsequently loaded into porous silicon nanoparticles (PSiNPs) via electrostatic interactions to construct PSiNPs@(Fe3O4/Au) nanocomposites. The as-prepared PSiNPs@(Fe3O4/Au) nanocomposites exhibited excellent super-paramagnetism, photothermal effect, and T2-weight magnetic resonance imaging capability. In particular, with the help of a magnetic field, the cellular uptake of PSiNPs@(Fe3O4/Au) nanocomposites was significantly enhanced in drug-resistant breast cancer cells. Moreover, PSiNPs@(Fe3O4/Au) nanocomposites as carriers showed a high loading and NIR light-triggered release of anticancer drugs. Based on the synergistic effect of magnetic field-enhanced cellular uptake and NIR light-triggered intracellular release, the amount of anticancer drug carried by PSiNPs@(Fe3O4/Au) nanocarriers into the nuclei of drug-resistant breast cancer cells sharply increased, accompanied by improved chemo-photothermal therapeutic efficacy. Finally, PSiNPs@(Fe3O4/Au) nanocomposites under the combined conditions of magnetic field attraction and NIR light irradiation also showed improved anticancer drug penetration and accumulation in three-dimensional multicellular spheroids composed of drug-resistant breast cancer cells, leading to a better growth inhibition effect. Overall, the fabricated PSiNPs@(Fe3O4/Au) nanocomposites demonstrated great potential for the therapy of multidrug-resistant breast cancer in future.

Synthesis and Application of Fe3O4@Au Composite Nanoparticles as Magnetic Resonance/Computed Tomography Dual-Modality Contrast Agent

Background:

None of the molecular imaging modalities can produce imaging with both anatomical and functional information. In recent years, to overcome these limitations multimodality molecular imaging or combination of two imaging modalities can provide anatomical and pathological information.

Methods:

Magnetic iron oxide nanoparticles were prepared by co-precipitation method and then were coated with silica according to Stober method. Consequently, silica-coated nanoparticles were amino-functionalized. Finally, gold nanoparticles assembled onto the surfaces of the previous product. Cytotoxicity effects of prepared Fe₃O₄@Au nanoparticles were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human hepatocellular carcinoma cells. Their ability as a dual-mode contrast agent was investigated by magnetic resonance (MR) and computed tomography (CT) imaging.

Results:

Fe₃O₄@Au nanoparticles were spherical undersize of 75 nm. X-ray diffraction analysis confirmed the formation of Fe₃O₄@Au nanoparticles. The magnetometry result confirmed the superparamagnetism property of prepared nanoparticles, and the saturation magnetization (M_s) was found to be 33 emu/g. Fe₃O₄@Au nanoparticles showed good cytocompatibility up to 60 μg/mL. The results showed that the Fe₃O₄@Au nanoparticles have good r₂ relaxivity (135.26 mM⁻¹s⁻¹) and good X-ray attenuation property.

Conclusion:

These findings represent that prepared Fe₃O₄@Au nanoparticles in an easy and relatively low-cost manner have promising potential as a novel contrast agent for dual-modality of MR/CT imaging.

Rapid Sonochemically-Assisted Synthesis of Highly Stable Gold Nanoparticles as Computed Tomography Contrast Agents

One of the most widely used modalities of clinical imaging is computed tomography (CT). Recent reports of new contrast agents toward CT imaging have been numerous. The production of gold nanoparticles (AuNPs) as contrast agents for CT is primarily a topic of intense interest. AuNPs have beneficial features for this application, including excellent X-ray attenuation, flexible sizes and shapes, tailorable surface chemistry, excellent biocompatibility and high levels of contrast generating matter. AuNPs with a size of about 18.5 nm and semi-spherical shape were synthesized using a sonochemical method. The attenuation rate of X-rays as measured in Hounsfield units per unit concentration (HU/mg) was measured. Ultrasound treatment for a duration of five min has been shown to produce highly stable AuNPs in different media (AuNPs in water and phosphate-buffered saline (PBS) was −42.1 mV and −39.5 mV, respectively). The CT value (HU = 395) of the AuNPs increased linearly with an increase in the AuNP dosage. The results confirm the use of ultrasonic treatment for the production of metal nanostructures, particularly highly stable non-toxic AuNPs, with good morphology and high-quality crystal structure using an easy and fast method. Synthesized AuNPs have the potential to be used as a CT contrast agent in medical imaging applications.

Innovative hydrolysis of corn stover biowaste by modified magnetite laccase immobilized nanoparticles

Intensive studies have been performed on the improvement of bioethanol production by transformation of lignocellulose biomass. In this study, the digestibility of corn stover was dramatically improved by using laccase immobilized on Cu²⁺ modified recyclable magnetite nanoparticles, Fe₃O₄-NH₂. After digestion, the laccase was efficiently separated from slurry. The degradation rate of lignin reached 40.76%, and the subsequent cellulose conversion rate 38.37% for 72 h at 35 °C with cellulase at 50 U g^-1 of corn stover. Compared to those of free and inactivated mode, the immobilized laccase pre-treatment increased subsequent cellulose conversion rates by 23.98% and 23.34%, respectively. Moreover, the reusability of immobilized laccase activity remained 50% after 6 cycles. The storage and thermal stability of the fixed laccase enhanced by 70% and 24.1% compared to those of free laccase at 65 °C, pH 4.5, respectively. At pH 10.5, it exhibited 16.3% more activities than its free mode at 35 °C. Our study provides a new avenue for improving the production of bioethanol with immobilized laccase for delignification using corn stover as the starting material.

Multifunctional Fe3O4-Au Nanoparticles for the MRI Diagnosis and Potential Treatment of Liver Cancer

Heterodimeric nanoparticles comprising materials with different functionalities are of great interest for fundamental research and biomedical/industrial applications. In this work, Fe₃O₄-Au nano-heterostructures were synthesized by a one-step thermal decomposition method. The hybrid nanoparticles comprise a highly crystalline 12 nm magnetite octahedron decorated with a single noble metal sphere of 6 nm diameter. Detailed analysis of the nanoparticles was performed by UV-visible spectroscopy, magnetometry, calorimetry and relaxometry studies. The cytotoxic effect of the nanoparticles in the human hepatic cell line Huh7 and PLC/PRF/5-Alexander was also assessed. These Fe₃O₄-Au bifunctional nanoparticles showed no significant cytotoxicity in these two cell lines. The nanoparticles showed a good theranostic potential for liver cancer treatment, since the r₂ relaxivity (166.5 mM⁻¹·s⁻¹ and 99.5 mM⁻¹·s⁻¹ in water and HepG2 cells, respectively) is higher than the corresponding values for commercial T₂ contrast agents and the Specific Absorption Rate (SAR) value obtained (227 W/g_Fe) is enough to make them suitable as heat mediators for Magnetic Fluid Hyperthermia. The gold counterpart can further allow the conjugation with different biomolecules and the optical sensing.

Polyethylenimine-Assisted Generation of Optical Nanoprobes for Biosensing Applications

Detection of analytes in biological systems is pivotal to explore their physiological roles and provide diagnostic and treatment options for related diseases, which however remains a great challenge. Optical nanoprobes that exhibit absorption or fluorescence signal changes in response to the targets of interest have emerged as a versatile class of biosensors in the field. Polyethylenimine (PEI) with abundant amine groups plays indispensable roles in the construction of optical nanoprobes and mediating the sensing processes. After interaction with analytes, PEI-based optical nanoprobes can be induced to form aggregates, be disassembled or separated into individual units, or undergo structure/component alterations. As such, the optical properties of these nanoprobes have corresponding changes, allowing for sensitive and selective detection of a wide variety of analytes in biological environment. Up to now, detections of reactive oxygen species, pH, metal ions, biothiols, neurotransmitters, therapeutic agents, oxygen levels, enzyme activities, and virus/bacteria have been successfully demonstrated using PEI-based optical nanoprobes. Herein, we summarize the recent developments of PEI-based optical nanoprobes for biosensing applications and highlight the probe designs and sensing mechanisms. The existing challenges and prospects regarding biosensing applications of PEI-based optical nanoprobes are also briefly discussed.

Gold-based Inorganic Nanohybrids for Nanomedicine Applications

Noble metal Au nanoparticles have attracted extensive interests in the past decades, due to their size and morphology dependent localized surface plasmon resonances. Their unique optical property, high chemical stability, good biocompatibility, and easy functionalization make them promising candidates for a variety of biomedical applications, including bioimaging, biosensing, and cancer therapy. With the intention of enhancing their optical response in the near infrared window and endowing them with additional magnetic properties, Au nanoparticles have been integrated with other functional nanomaterials that possess complementary attributes, such as copper chalcogenides and magnetic metal oxides. The as constructed hybrid nanostructures are expected to exhibit unconventional properties compared to their separate building units, due to nanoscale interactions between materials with different physicochemical properties, thus broadening the application scope and enhancing the overall performance of the hybrid nanostructures. In this review, we summarize some recent progresses in the design and synthesis of noble metal Au-based hybrid inorganic nanostructures for nanomedicine applications, and the potential and challenges for their clinical translations.

Physical and Biological Evaluation of Low-Molecular-Weight Hyaluronic Acid/Fe3O4 Nanoparticle for Targeting MCF7 Breast Cancer Cells

Low-molecular-weight hyaluronic acid (LMWHA) was integrated with superparamagnetic Fe₃O₄ nanoparticles (Fe₃O₄ NPs). The size distribution, zeta potential, viscosity, thermogravimetric and paramagnetic properties of the LMWHA-Fe₃O₄ NPs were systematically examined. For cellular experiments, MCF7 breast cancer cell line was carried out. In addition, the cell targeting ability and characteristics of the LMWHA-Fe₃O₄ NPs for MCF7 breast cancer cells were analyzed using the thiocyanate method and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The experimental results showed that the LMWHA-Fe₃O₄ NPs were not only easily injectable due to their low viscosity, but also exhibited a significant superparamagnetic property. Furthermore, the in vitro assay results showed that the NPs had negligible cytotoxicity and exhibited a good cancer cell targeting ability. Overall, the results therefore suggest that the LMWHA-Fe₃O₄ NPs have considerable potential as an injectable agent for enhanced magnetic resonance imaging (MRI) and/or hyperthermia treatment in breast cancer therapy.

One-pot preparation of hyaluronic acid-coated iron oxide nanoparticles for magnetic hyperthermia therapy and targeting CD44-overexpressing cancer cells

In the present study, a facile one-pot hydrothermal method is introduced for preparation of hyaluronic acid-coated Fe₃O₄ nanoparticles (Fe₃O₄@HA NPs) for theranostic applications. In the proposed method, hyaluronic acid acts simultaneously as a biocompatible coating layer and as a targeting ligand for CD44 receptor overexpressed on the surface of breast cancer cells. The obtained product with narrow hydrodynamic size distribution exhibited a high colloidal stability at physiological pH for more than three months. Cytotoxicity measurements indicated a negligible toxicity of the prepared sample against L929 normal cells. Preferential targeting of Fe₃O₄@HA NPs to CD44-overexpressing cancer cells was studied by comparing the uptake of the prepared nanoparticles by MDA-MB-231 cancer cells (positive CD44 expression) and L929 normal cells (negative CD44 expression). Uptake of the Fe₃O₄@HA NPs by MDA-MB-231 cells was found to be 4-fold higher than the normal cells. Also, the in vitro analysis showed that, the uptake of Fe₃O₄@HA NPs by MDA-MB-231 breast cancer cells is significantly enhanced as compared to non-targeted dextran-coated Fe₃O₄ NPs. Moreover, the heat generation capability of the Fe₃O₄@HA NPs for magnetic hyperthermia application was studied by exposing the prepared nanoparticles to different safe alternating magnetic fields (f = 120 kHz, H = 8, 10, and 12 kA/m). The intrinsic loss power obtained for Fe₃O₄@HA NPs was about 3.5 nHm²/kg, which is about 25-fold larger than that of obtained for commercial available Fe₃O₄ nanoparticles for biomedical applications. Good colloidal stability, biocompatibility, high heating efficacy, and targeting specificity to CD44 receptor-overexpressing cancer cells could make the Fe₃O₄@HA NPs as a promising multifunctional platform for diagnosis and therapeutic applications.

Aptamer/magnetic nanoparticles decorated with fluorescent gold nanoclusters for selective detection and collection of human promyelocytic leukemia (HL-60) cells from a mixture

In the present work, a fluorescent gold nanoclusters (GNCs)/superparamagnetic (Fe₃O₄/GNCs) nanoprobe was prepared via a facile approach for the selective detection and imaging of human leukemica cancer cells (HL-60). (γ-Mercaptopropyl)trimethoxysilane (MPS) was used as a stabilizer to prepare functionalized GNCs. The prepared GNCs@MPS was then self-assembly decorated on the surface of Fe₃O₄@SiO₂ nanoparticles followed by poly(ethylene glycol) dimethacrylate (PGD) addition at room temperature to form Fe₃O₄/GNCs nanoprobe. Surface functionalization of the Fe₃O₄/GNCs with the thiol-modified KH1C12 aptamer was done through thiol-en click reaction between PGD and the thiol group of the aptamer. An extensive characterization of the Fe₃O₄/GNCs revealed strong red fluorescence (λ _em = 627 nm), T ₂-based contrast agent for MRI and excellent colloidal and photo stability in buffer medium. So, the aptamer-functionalized Fe₃O₄/GNCs nanoprobe (Fe₃O₄/GNCs/Aptamer) is capable to uptake and dual-image HL-60 cancer cells from a mixture. Furthermore, the MRI signal intensity of the pictures decreased linearly with an increase in the concentrations of the nanoprobe. It is also enable to detect cancer cells from a range of concentrations 10 up to 200 cells μL^-1. The fluorescent/magnetic characteristics of the nanoprobe are of great significance for MRI-based and fluorescence imaging and collection of HL-60 cancer cells which implies potential help for the development of early diagnosis of highly malignant human leukemia.

Core–shell structured magnetic mesoporous silica supported Schiff-base/Pd: an efficacious and reusable nanocatalyst

Preparation, characterization and catalytic application of a novel magnetic ordered mesoporous silica supported Schiff-base/Pd (Fe₃O₄@MCM-41-SB/Pd) are developed.

Multi-functional FITC-silica@gold nanoparticles conjugated with guar gum succinate, folic acid and doxorubicin for CT/fluorescence dual imaging and combined chemo/PTT of cancer

A novel type of multi-functional fluorescein isothiocyanate (FITC)-silica (SiO₂)@gold (Au) core-shell nanoparticles covered with folic acid (FA)-conjugated guar gum succinate (GGS) and doxorubicin (DOX) (FITC-SiO₂@Au-DOX-GGS-FA NPs) was prepared for imaging and therapy of cancer. The physicochemical properties of these NPs were analyzed with ¹H NMR, TEM and DLS. The FITC-SiO₂@Au-DOX-GGS-FA NPs exhibited the fluorescence and X-ray attenuation properties due to the presence of FITC-SiO₂@Au hybrid nanostructure. Due to acid-cleavable hydrazone bond between the DOX and NPs, the quantity of DOX delivered from the FITC-SiO₂@Au-DOX-GGS-FA NPs was increased at pH 5.6 than that at pH 7.4. Besides, the multi-functional NPs presented the improved cellular uptake by HeLa cells via FA-receptor-mediated endocytosis due to the existence of FA. The developed NPs also presented the improved cytotoxicity towards the HeLa cells due to its tumor-targetability and DOX/photothermal effect. These results suggested that the FITC-SiO₂@Au-DOX-GGS-FA NPs could be ideal for computed tomography (CT)/fluorescence dual imaging and combined chemo/photothermal therapy (PTT) of cancer.

99mTc-Labeled Polyethylenimine-Entrapped Gold Nanoparticles with pH-Responsive Charge Conversion Property for Enhanced Dual Mode SPECT/CT Imaging of Cancer Cells

Development of tumor dual mode contrast agents is still a great challenge due to the relative low accumulation at tumor site, which result in the poor imaging efficiency. In this study, we constructed functional technetium-99m (^99mTc) labeled polyethylenimine (PEI)-entrapped gold nanoparticles (Au PENs) with pH-responsive charge conversion property for enhanced single photon emission computed tomography (SPECT)/computed tomography (CT) dual mode imaging of cancer cells. PEI with amine functional groups (PEI.NH₂) was successively modified with monomethyl ether and carboxyl functionalized polyethylene glycol (mPEG-COOH), maleimide and succinimidyl valerate functionalized PEG (MAL-PEG-SVA), diethylenetriaminepentaacetic dianhydride (DTPA), and fluorescein isothiocyanate (FI), and used to entrapped gold nanoparticles inside, followed by conjugation with the alkoxyphenyl acylsulfonamide (APAS) through the PEG maleimide, acetylation of the PEI leftover surface amines and ^99mTc labeling. The created nanosystem with the mean Au core diameter of 3.3 nm and with a narrow size distribution displays an excellent colloidal stability and desired cytocompatibility in the investigated Au concentration range. Due to the fact that the attached APAS moieties are responsive to pH, the functionalized Au PENs with a neutral surface charge can switch to be positively charged under slightly acidic pH condition, which could improve the cellular uptake by cancer cells. With these properties, the developed functionalized Au PENs could achieve enhanced dual mode SPECT/CT imaging of cancer cells in vitro. The constructed PEI-based nanodevices may be adopted as an excellent dual mode contrast agent for SPECT/CT imaging of cancer cells of different types.

Fluorescein sodium loaded by polyethyleneimine for fundus fluorescein angiography improves adhesion

Aim: To improve the retention of fluorescein sodium (FS) as a kind of clinical contrast agent for fundus fluorescein angiography (FFA). Materials & methods: Polyethyleneimine (PEI) was designed to synthesize PEI–NHAc–FS nanoparticles (NPs), and the formed NPs were characterized by both physicochemical properties and their effects on FFA. Results: Compared with free FS, PEI–NHAc–FS NPs showed similar optical performance, and could obviously reduce cellular adsorption and uptake both in vitro and in vivo, which could promote the metabolism of NPs in ocular blood vessels. Conclusion: PEI–NHAc–FS NPs represent a smart nanosize fluorescence contrast agent, which hold promising potential for clinical FFA diagnosis, therapy and research work.

Multimodal Composite Iron Oxide Nanoparticles for Biomedical Applications

Background

Iron oxide nanoparticles (IONPs) are excellent candidates for biomedical imaging because of unique characteristics like enhanced colloidal stability and excellent in vivo biocompatibility. Over the last decade, material scientists have developed IONPs with better imaging and enhanced optical absorbance properties by tuning their sizes, shape, phases, and surface characterizations. Since IONPs could be detected with magnetic resonance imaging, various attempts have been made to combine other imaging modalities, thereby creating a high-resolution imaging platform. Composite IONPs (CIONPs) comprising IONP cores with polymeric or inorganic coatings have recently been documented as a promising modality for therapeutic applications.

Methods

In this review, we provide an overview of the recent advances in CIONPs for multimodal imaging and focus on the therapeutic applications of CIONPs.

Result

CIONPs with phototherapeutics, IONP-based nanoparticles are used for theranostic application via imaging guided photothermal therapy.

Conclusion

CIONP-based nanoparticles are known for theranostic application, longstanding effects of composite NPs in in vivo systems should also be studied. Once such issues are fixed, multifunctional CIONP-based applications can be extended for theranostics of diverse medical diseases in the future.

Advances in Magnetic Noble Metal/Iron-Based Oxide Hybrid Nanoparticles as Biomedical Devices

The study of the noble metal magnetic hybrid nanoparticles is a really promising topic from both the scientific and the technological points of views, with applications in several fields. Iron oxide materials which are hybridized with noble metal nanoparticles (NPs) have attracted increasing interest among researchers because of their cooperative effects on combined magnetic, electronic, photonic, and catalytic activities. This review article contains a summary of magnetic noble metal/iron oxide nanoparticle systems potentially useful in practical biomedical applications. Among the applications, engineered devices for both medical diagnosis and treatments were considered. The preparation to produce different structures, as blends or core-shell structures, of several nanometric systems was also considered. Several characterization techniques available to describe the structure, morphology and different kinds of properties of hybrid nanoparticles are also included in this review.

Gold nanoparticles-loaded hydroxyapatite composites guide osteogenic differentiation of human mesenchymal stem cells through Wnt/β-catenin signaling pathway

BACKGROUND

Precise control and induction of the differentiation of stem cells to osteoblasts by artificial biomaterials are a promising strategy for rapid bone regeneration and reconstruction.

PURPOSE

In this study, gold nanoparticles (AuNPs)-loaded hydroxyapatite (HA-Au) nanocomposites were designed to guide the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs) through the synergistic effects of both AuNPs and HA.

MATERIALS AND METHODS

The HA-Au nanoparticles were synthesized and characterized by several analytical techniques. Cell viability and proliferation of hMSCs were characterized by CCK-8 test. Cellular uptake of nanoparticles was observed by transmission electron microscope. For the evaluation of osteogenic differentiation, alkaline phosphatase (ALP) activity and staining, Alizarin red staining, and a quantitative real-time polymerase chain reaction (RT-PCR) analysis were performed. In order to examine specific signaling pathways, RT-PCR and Western blotting assay were performed.

RESULTS

The results confirmed the successful synthesis of HA-Au nanocomposites. The HA-Au nanoparticles showed good cytocompatibility and internalized into hMSCs at the studied concentrations. The increased level of ALP production, deposition of calcium mineralization, as well as the expression of typical osteogenic genes, indicated the enhancement of osteogenic differentiation of hMSCs. Moreover, the incorporation of Au could activate the Wnt/β-catenin signaling pathway, which seemed to be the molecular mechanism underlying the osteoinductive capability of HA-Au nanoparticles.

CONCLUSION

The HA-Au nanoparticles exerted a synergistic effect on accelerating osteogenic differentiation of hMSCs, suggesting they may be potential candidates for bone repair and regeneration.

Modified core–shell magnetic mesoporous zirconia nanoparticles formed through a facile “outside-to-inside” way for CT/MRI dual-modal imaging and magnetic targeting cancer chemotherapy

Iron oxide based magnetic nanoparticles (MNPs) as typical theranostic nanoagents have been popularly used in various biomedical applications. Conventional core–shell MNPs are usually synthesized from inside to outside. This method has strict requirements on the interface properties of magnetic cores and the precursors of the coating shell. The shape and size of MNPs are significantly influenced by that of the pre-synthesized magnetic cores. Most core–shell MNPs have only single T2W MRI imaging ability. Herein, we propose a new synthetic strategy for core-mesoporous shell structural MNPs, where hollow mesoporous nanospheres which exhibit an intrinsic property for both CT imaging and drug loading were used as the shell and the magnetic cores were produced in the cavity of the shell. A new type of MNPs, Fe₃O₄@ZrO₂ nanoparticles (M-MZNs), were developed using this facile outside-to-inside way, where multiple Fe₃O₄ nanoparticles grew inside the cavity of the mesoporous hollow ZrO₂ nanospheres through chemical coprecipitation. The obtained MNPs not only exhibited superior magnetic properties and CT/MR imaging ability but also high drug loading capacity. In vitro experiment results revealed that M-MZNs-PEG loaded with doxorubicin (DOX) presented selective growth inhibition against cancer cells due to pH-sensitive DOX release and enhanced endocytosis by cancer cells under a magnetic field. Furthermore, the proposed MNPs exhibited CT/MRI dual modal imaging ability and effective physical targeting to tumor sites in vivo. More importantly, experiments of magnetic targeting chemotherapy on tumor bearing mice demonstrated that the nanocomposites significantly suppressed tumor growth without obvious pathological damage to major organs. Henceforth, this study provides a new strategy for CT/MRI dual-modal imaging guided and magnetic targeting cancer therapy.

Magnetic mesoporous zirconia nanoparticle was synthesized by producing multiple iron oxide cores inside the cavity of mesoporous ZrO₂ hollow nanospheres and was used for CT/MRI dual-modal imaging and magnetic targeting chemotherapy.

Polyethyleneimine-Coated Manganese Oxide Nanoparticles for Targeted Tumor PET/MR Imaging

A Mn₃O₄ nanoparticle (NP)-based dual-modality probe has been developed for tumor positron emission tomography (PET)/magnetic resonance (MR) imaging. The dual-modality imaging probe was constructed by modifying multifunctional polyethyleneimine (PEI)-coated Mn₃O₄ NPs with folic acid (FA), followed with the radiolabeling with ⁶⁴Cu. The formed imaging probe was utilized for PET/MR imaging of human cervical cancer mouse xenografts, which overexpress folate receptor (FR). The PEI-coated Mn₃O₄ NPs were synthesized using a solvothermal approach via decomposition of acetylacetone manganese. Multifunctional groups, including fluorescein isothiocyanate (FI), PEGylated FA, and NOTA chelator, were then sequentially loaded onto the surface of the amine groups of the Mn₃O₄ NPs. The remaining PEI amines were neutralized by the acetylation reaction. The resulting NOTA-FA-FI-PEG-PEI-Ac-Mn₃O₄ NPs were fully characterized and evaluated in vitro and successfully radiolabeled with ⁶⁴Cu for tumor PET/MR imaging in small animals. In vivo blocking experiments were performed to determine the FR binding specificity of NPs. PET imaging results demonstrated that ⁶⁴Cu-labeled Mn₃O₄ NPs display good tracer uptake in the FR-expressing HeLa tumors (tumor-to-muscle (T/M) ratio: 5.35 ± 0.31 at 18 h postinjection (pi)) and substantially reduced tracer uptake in the FR-blocked HeLa tumors (T/M ratio: 2.78 ± 0.68 at 18 h pi). The ex vivo data, including PET imaging and biodistribution, further confirmed the tumor binding specificity of the ⁶⁴Cu-labeled Mn₃O₄ NPs. Moreover, the FR-targeted Mn₃O₄ NPs exhibited efficient T₁-weighted MR imaging (MRI), leading to the precise tumor MRI at 18 h pi. PET/MR imaging with the ⁶⁴Cu-NOTA-FA-FI-PEG-PEI-Ac-Mn₃O₄ NPs may offer a new quantitative approach to precisely measure the FR in tumors. The strategy of incorporating PEI nanotechnology into the construction of new biomaterials may be applied for the construction of novel nanoplatforms for cancer diagnosis and therapy.

Carbon coated core-shell multifunctional fluorescent SPIONs

Due to their unique magnetic properties, multiple surface functionality and biocompatibility, superparamagnetic iron oxide nanoparticles (SPIONs) show very promising characteristics as magnetic resonance (MR) contrast agents in biomedical applications. However, a lack of fluorescence makes SPIONs inappropriate for multimodal bioimaging. SPIONs surface functionalized by either organic fluorescent molecules or semiconductor quantum dots (QDs) have been reported as bioimaging probes but subsequent deterioration of the fluorescent dyes due to low photostability and quick photobleaching limits their long term practical application. In addition, QDs are found to be toxic in nature. Here, we present a novel one step method to synthesize non-toxic carbon coated highly photostable core-shell magnetic and fluorescent SPIONs with long-lasting fluorescence alongside a superior magnetic resonance (MR) imaging ability. Apart from the highly comparable superparamagnetic properties of the SPIONs, the optical response of the material is much better than commonly used Rhodamine or cyanine dyes.

Iron Oxide and Gold Based Magneto-Plasmonic Nanostructures for Medical Applications: A Review

Iron oxide and gold-based magneto-plasmonic nanostructures exhibit remarkable optical and superparamagnetic properties originating from their two different components. As a consequence, they have improved and broadened the application potential of nanomaterials in medicine. They can be used as multifunctional nanoprobes for magneto-plasmonic heating as well as for magnetic and optical imaging. They can also be used for magnetically assisted optical biosensing, to detect extreme traces of targeted bioanalytes. This review introduces the previous work on magneto-plasmonic hetero-nanostructures including: (i) their synthesis from simple “one-step” to complex “multi-step” routes, including seed-mediated and non-seed-mediated methods; and (ii) the characterization of their multifunctional features, with a special emphasis on the relationships between their synthesis conditions, their structures and their properties. It also focuses on the most important progress made with regard to their use in nanomedicine, keeping in mind the same aim, the correlation between their morphology—namely spherical and non-spherical, core-satellite and core-shell, and the desired applications.

Construction of iron oxide nanoparticle-based hybrid platforms for tumor imaging and therapy

This review highlights the most recent progress in the construction of iron oxide nanoparticle-based hybrid platforms for tumor imaging and therapy.

A unique nanogel-based platform for enhanced dual mode tumor MR/CT imaging

Alginate nanogels loaded with gold nanoparticles and gadolinium can be synthesized via a nanoparticle-crosslinking approach for enhanced tumor MR/CT imaging.

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

In order to translate nanotechnology into medical practice, magnetic nanoparticles (MNPs) have been presented as a class of non-invasive nanomaterials for numerous biomedical applications. In particular, MNPs have opened a door for simultaneous diagnosis and brisk treatment of diseases in the form of theranostic agents. This review highlights the recent advances in preparation and utilization of MNPs from the synthesis and functionalization steps to the final design consideration in evading the body immune system for therapeutic and diagnostic applications with addressing the most recent examples of the literature in each section. This study provides a conceptual framework of a wide range of synthetic routes classified mainly as wet chemistry, state-of-the-art microfluidic reactors, and biogenic routes, along with the most popular coating materials to stabilize resultant MNPs. Additionally, key aspects of prolonging the half-life of MNPs via overcoming the sequential biological barriers are covered through unraveling the biophysical interactions at the bio-nano interface and giving a set of criteria to efficiently modulate MNPs' physicochemical properties. Furthermore, concepts of passive and active targeting for successful cell internalization, by respectively exploiting the unique properties of cancers and novel targeting ligands are described in detail. Finally, this study extensively covers the recent developments in magnetic drug targeting and hyperthermia as therapeutic applications of MNPs. In addition, multi-modal imaging via fusion of magnetic resonance imaging, and also innovative magnetic particle imaging with other imaging techniques for early diagnosis of diseases are extensively provided.

Aqueous-phase synthesis of iron oxide nanoparticles and composites for cancer diagnosis and therapy

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.