Transferrin-targeted magnetic/fluorescence micelles as a specific bi-functional nanoprobe for imaging liver tumor

In order to delineate the location of the tumor both before and during operation, we developed targeted bi-functional polymeric micelles for magnetic resonance (MR) and fluorescence imaging in liver tumors. Hydrophobic superparamagnetic iron oxide nanoparticles (SPIONs) were loaded into the polymeric micelles through self-assembly of an amphiphilic block copolymer poly(ethylene glycol)-poly(ϵ-caprolactone). After, transferrin (Tf) and near-infrared fluorescence molecule Cy5.5 were conjugated onto the surface of the polymeric micelles to obtain the nanosized probe SPIO@PEG-b-PCL-Tf/Cy5.5 (SPPTC). Imaging capabilities of this nanoprobe were evaluated both in vitro and in vivo. The accumulation of SPPTC in HepG2 cells increased over SPIO@PEG-b-PCL-Cy5.5 (SPPC) by confocal microscopy. The targeted nanoprobe SPPTC possessed favorable properties on the MR and fluorescence imaging both in vitro and in vivo. The MTT results showed that the nanoprobes were well tolerated. SPPTC had the potential for pre-operation evaluation and intra-operation navigation of tumors in clinic.     

Magnetic resonance imaging of glioma with novel APTS-coated superparamagnetic iron oxide nanoparticles

We report in vitro and in vivo magnetic resonance (MR) imaging of C6 glioma cells with a novel acetylated 3-aminopropyltrimethoxysilane (APTS)-coated iron oxide nanoparticles (Fe₃O₄ NPs). In the present study, APTS-coated Fe₃O₄ NPs were formed via a one-step hydrothermal approach and then chemically modified with acetic anhydride to generate surface charge-neutralized NPs. Prussian blue staining and transmission electron microscopy (TEM) data showed that acetylated APTS-coated Fe₃O₄ NPs can be taken up by cells. Combined morphological observation, cell viability, and flow cytometric analysis of the cell cycle indicated that the acetylated APTS-coated Fe₃O₄ NPs did not significantly affect cell morphology, viability, or cell cycle, indicating their good biocompatibility. Finally, the acetylated APTS-coated Fe₃O₄ nanoparticles were used in magnetic resonance imaging of C6 glioma. Our results showed that the developed acetylated APTS-coated Fe₃O₄ NPs can be used as an effective labeling agent to detect C6 glioma cells in vitro and in vivo for MR imaging. The results from the present study indicate that the developed acetylated APTS-coated Fe₃O₄ NPs have a potential application in MR imaging.     

Synthesis of PEGylation hydroxyapatite drug delivery system and its dual channels fluorescence imaging

PEGylated drug delivery systems (DDSs) can overcome the side effects of traditional chemotherapy by enhancing drug permeability and retention (EPR) effects. In this work, DOX@HAP (hydroxyapatite) was initially fabricated via the coprecipitation and hydrothermal method, further functionalized with Cy (cyanine) by coupling reaction of APTES and then introduced hydrophilic PEG chains by using copper(I)-catalyzed alkyne–azide cycloaddition reaction. Physicochemical properties including the morphology, particle size and phase composition, were characterized by TEM, SEM, particle size analyzer, FTIR, XPS and XRD. The encapsulation efficiency and drug release profile of DOX@HAP-Cy-PEG were analyzed by UV-Vis spectrophotometry. Furthermore, the cellular uptake of DOX@HAP-Cy-PEG nanoparticles in Hela and HepG2 cells was monitored by the dual channels fluorescence imaging of DOX and Cy. The results showed that DOX@HAP-Cy-PEG nanoparticles could be used to real-time monitor the dynamic distribution of DDSs in Hela and HepG2 cells by dual channels.     

PEG化羟基磷灰石纳米体系的制备及双通道荧光成像

PEG化的药物递送系统(DDSs)可以通过增强药物的渗透性和滞留性(EPR)效应克服传统化疗的副作用。利用共沉淀法和水热法制备纳米粒子DOX@HAP,进一步通过偶联反应修饰菁染料(Cy),通过铜(I)催化的炔-叠氮化物环加成反应修饰PEG链,构建了纳米制剂DOX@HAP-Cy-PEG。通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)、粒度分析仪、傅里叶红外光谱仪(FTIR)、X射线光电子能谱仪(XPS)和X射线衍射仪(XRD)对该纳米载药体系的形貌、粒径、物相组成进行表征分析。利用紫外-可见(UV-Vis)分光光度法测定了该纳米材料的药物负载量以及体外药物释放曲线。进一步,利用DOX和Cy双通道荧光成像,监测DDSs在Hela和HepG2细胞中的摄取行为。表明DOX@HAP-Cy-PEG纳米载药体系有望作为一种新型的治疗与示踪一体化的抗癌纳米制剂。     

Development of SNAP-tag fluorogenic probes for wash-free fluorescence imaging

The ability to specifically attach chemical probes to individual proteins represents a powerful approach to the study and manipulation of protein function in living cells. It provides a simple, robust and versatile approach to the imaging of fusion proteins in a wide range of experimental settings. However, a potential drawback of detection using chemical probes is the fluorescence background from unreacted or nonspecifically bound probes. In this report we present the design and application of novel fluorogenic probes for labeling SNAP-tag fusion proteins in living cells. SNAP-tag is an engineered variant of the human repair protein O(6)-alkylguanine-DNA alkyltransferase (hAGT) that covalently reacts with benzylguanine derivatives. Reporter groups attached to the benzyl moiety become covalently attached to the SNAP tag while the guanine acts as a leaving group. Incorporation of a quencher on the guanine group ensures that the benzylguanine probe becomes highly fluorescent only upon labeling of the SNAP-tag protein. We describe the use of intramolecularly quenched probes for wash-free labeling of cell surface-localized epidermal growth factor receptor (EGFR) fused to SNAP-tag and for direct quantification of SNAP-tagged β-tubulin in cell lysates. In addition, we have characterized a fast-labeling variant of SNAP-tag, termed SNAP(f), which displays up to a tenfold increase in its reactivity towards benzylguanine substrates. The presented data demonstrate that the combination of SNAP(f) and the fluorogenic substrates greatly reduces the background fluorescence for labeling and imaging applications. This approach enables highly sensitive spatiotemporal investigation of protein dynamics in living cells.     

Fluorine depth profiling by high-resolution 1D magnetic resonance imaging

High-resolution magnetic resonance imaging (MRI) has been used, for the first time, to measure fluorine concentration profiles with a high spatial resolution (5 μm) along the full film depth of fluorinated polyurethane films. The MRI fluorine profiles were consistent with the results obtained by X-ray photoelectron spectroscopy (XPS) in combination with microtoming. MRI is a nondestructive and potentially quantitative technique for probing the spatial distribution of small quantities of fluorine in coatings and multi-layered systems.     

The mixing state of fine powders measured by magnetic resonance imaging

The usefulness of magnetic resonance imaging (MRI) for the spatially resolved, quantitative characterization of mixtures of fine powders in the size range of about 10 μm is investigated. The sources of errors inherent in the signal translation process between raw MRI data and local concentrations are analyzed in detail. Possibilities for their correction are pointed out in deriving a global characteristic such as the standard deviation.The analysis of the mixing state of powders by MRI and the benefits of error correction are then illustrated by simple examples covering a wide range of compositions and mixing states. These experiments were made by mixing spherical, oil-filled (hence “visible” to MRI) melamine microcapsules in the size range of about 1-20 μm with solid melamine spheres of similar size and density. The mixture volume of typically 1 cm³ was imaged with an isotropic resolution of 235 μm, providing over 60,000 contiguous data points per measurement. The benefit of error correction is shown to be significant, provided the mixtures are homogeneous to a large extent.     

Crystallization dynamics in model emulsions from magnetic resonance imaging

Melt crystallization of trilaurin and trimyristin was investigated in the bulk and in dispersed systems using magnetic resonance imaging. Crystallization rates were studied as a function of time in fat/water (40:60) emulsions containing 0.5% tween 80 and 0.2% xanthan gum to prevent creaming. Oil weighted images were obtained to follow the dynamics of crystallization in the bulk and in an emulsified system. Localized spectroscopy using a stimulated echo pulse sequence was used to quantify the crystallization dynamics pattern at different locations in a trimyristin emulsion (40:60). The results showed that crystallization in the emulsified state occurred over a longer period of time than in the bulk. Imaging allowed for the qualitative visualization of crystallization. Images showed crystallization occurring from the edge to the center. On the other hand, localized spectroscopy allowed for spatially quantitative measurement of the amount of liquid oil, crystalline oil and water. In the trimyristin emulsion (40:60), spectra recorded from the top, center and bottom showed a relatively abrupt crystallization pattern starting earlier at the edges of the container, as previously visualized by the images taken.     

An investigation of complex hybrid suspension flows by magnetic resonance imaging

An increasing number of industrially relevant suspensions, e.g., stabilized flows, backfill and codisposal systems, differ from conventional transport systems. Analysis of these suspensions is difficult due to their non‐Newtonian behavior and increased particle/particle interaction. This paper presents data obtained in a 100 mm diameter pipe test loop using magnetic resonance imaging (MRI). The flows considered are “stable” suspensions of coarse particles in visco‐plastic carrier fluids that are capable of statically suspending the solids. Particle concentration and fluid velocity maps are presented for a number of flow conditions which show that laminar flow of these suspensions is stratified rather than homogenous.     

pH-responsive magnetic mesoporous silica nanospheres for magnetic resonance imaging and drug delivery

Multi-functional magnetic mesoporous silica nanospheres (MMSNs), which were coated with poly(acrylic acid) (PAA), have been synthesized using the atom transfer radical polymerization of tert-butyl acrylate on the surface of MMSNs followed by the hydrolysis of the grafted poly(tert-butyl acrylate) chains. The resulting MMSN-PAA nanocomposites exhibit negligible cytotoxicity toward HeLa and L02 cells. Magnetic resonance imaging (MRI) studies reveal that the nanocomposites can be effectively taken-up by the cancer cells. The anticancer drug doxorubicin hydrochloride (DOX) can be loaded into the nanocomposites and subsequently released in a sustained and pH-responsive way because of the presence of pH-sensitive polymer shells. The DOX-loaded nanocomposites exhibit notable cytotoxicity to HeLa cancer cells. These results demonstrate that the pH-responsive MMSN-PAA nanocomposites can be applied to biological systems for MRI and drug delivery.     

Graphene oxide/zinc ferrite nanocomposite loaded with doxorubicin as a potential theranostic mediu in cancer therapy and magnetic resonance imaging

Hybrid functional biomaterials are attracting increasing interest due to their biocompatibility and therapeutic and diagnostic characteristics. The theranostic properties of functional biomaterials favor their application. When these materials are responded to stimuli, they confer target site delivery. Although various types of nanocomposites have been developed for drug delivery and diagnostics, no ideal composites have been reported yet. Here, we report the synthesis of graphene oxide–zinc ferrite hybrid nanocomposites (GO-ZnFe₂O₄) conjugated with doxorubicin (GO-ZnFe₂O₄/DOX) for cancer therapy and magnetic resonance (MR) imaging-based diagnosis. The optical properties, crystal phase, particle size, functional groups, elemental composition, surface morphology, and magnetism of GO-ZnFe₂O₄ nanocomposites were characterized using state-of-the-art available techniques, including Fourier-Transform Infrared Spectroscopy (FTIR), Ultraviolet visible spectroscopy (UV–Vis), Transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Dynamic light scattering (DLS), Vibrating sample magneto meter (VSM) Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray photoelectron spectra (XPS). The in vitro analysis showed that GO-ZnFe₂O₄ conjugated with DOX is more cytotoxic than GO-ZnFe₂O₄. GO-ZnFe₂O₄/DOX induced the production of reactive oxygen species (ROS), which induced damage to nuclear DNA and mitochondrial DNA (mtDNA) when internalized by cells. This damage consequently drove mitochondrial malfunction and ultimately the apoptosis of cancer cells. Further studies were performed to investigate the diagnostic efficacy of these nanocomposites using MR imaging. GO-ZnFe₂O₄/DOX nanocomposites were developed and successfully employed in the MR imaging of HeLa cells. As shown in the present study, GO-ZnFe₂O₄/DOX might play a potential role in the development of chemotherapy and noninvasive MR imaging of tumor cells.     

Multifunctional gadofulleride nanoprobe for magnetic resonance imaging/fluorescent dual modality molecular imaging and free radical scavenging

Strategic design of gadofullerene derivatives is critical to integrate multifunctionality into one entity. Herein, an easy method was developed to fabricate a new type of magnetic resonance imaging/fluorescent integrative molecular imaging probe based on Gd@C₈₂. The functionalized gadofulleride Gd@C₈₂O_∼14(OH)_∼14(NH₂)_∼6 not only exhibits an order of magnitude larger relaxivity (47.0 ± 0.8 mM⁻¹ s⁻¹ at 0.5 T) than commercially used gadopentetic acid (4.5 ± 0.1 mM⁻¹ s⁻¹) under the same condition and multi-wavelength emission features derived from the multi-wavelength excitation for dual-modality diagnosis, but also highly efficient scavenging capability toward hydroxyl radicals.     

Site-directed drug release performance in chemically-modified FeFe2O4 and CoFe2O4 magnetic nanoparticles for controlled drug delivery systems

This paper proposes a novel approach to the development of magnetic nanoparticles (MNPs) for drug delivery systems. The nanocarriers are made from FeFe₂O₄ and CoFe₂O₄ MNPs that were synthesized by combustion, coated with silica derivatives, and then conjugated to ciprofloxacin. The drug release tests were performed into simulated body fluid consisted of ciprofloxacin adsorbed onto MNPs composites with various mass ratios of hydroxyapatite:FeFe₂O₄ (M) and hydroxyapatite:CoFe₂O₄ (C), evaluated by pharmacokinetic models, and regression analysis. The MNPs were characterized by morphological and structural characterizations. Drug release was measured with a discontinuous method (paddle apparatus) and with a continuous method simulating a blood vessel. XRD and FTIR showed that all of the MNPs were successfully synthesized, coated, and drug conjugated. VSM exhibited superparamagnetic characteristics, with saturation magnetization varying between 9.74 and 32.90 emu/g and 9.65–30.00 emu/g for FeFe₂O₄ and CoFe₂O₄, respectively, as a function of the MNPs mass ratio on the nanocarrier. The discontinuous method showed drug release over 80% (FeFe₂O₄), while the CoFe₂O₄-based achieved over 40%, which indicates that the incorporation of hydroxyapatite favors the carrying of ciprofloxacin. The continuous method showed a drug release under 14% and 14.5% for the FeFe₂O₄ and CoFe₂O₄ based nanocarriers respectively, and this reduction of the desorbed drug compared to the discontinuous method may have occurred due to the action of the applied magnetic field. The mathematical model provided the release speed and time to reach the maximum fraction desorbed (<4 min), highlighted for M₂ (13.8%) and C₃ (14.5%) drug released, with a mass ratio of 50:50 and 30:70, respectively. The proposed continuous release model showed that the action of site-directed targeting significantly affected the amount of drug released. This identifies the optimal device for the development of magnetic nanoparticulate systems for drug delivery and tissue engineering.     

Size-regulated group separation of CoFe2O4 nanoparticles using centrifuge and their magnetic resonance contrast properties

Magnetic nanoparticle (MNP)-based magnetic resonance imaging (MRI) contrast agents (CAs) have been the subject of extensive research over recent decades. The particle size of MNPs varies widely and is known to influence their physicochemical and pharmacokinetic properties. There are two commonly used methods for synthesizing MNPs, organometallic and aqueous solution coprecipitation. The former has the advantage of being able to control the particle size more effectively; however, the resulting particles require a hydrophilic coating in order to be rendered water soluble. The MNPs produced using the latter method are intrinsically water soluble, but they have a relatively wide particle size distribution. Size-controlled water-soluble MNPs have great potential as MRI CAs and in cell sorting and labeling applications. In the present study, we synthesized CoFe₂O₄ MNPs using an aqueous solution coprecipitation method. The MNPs were subsequently separated into four groups depending on size, by the use of centrifugation at different speeds. The crystal shapes and size distributions of the particles in the four groups were measured and confirmed by transmission electron microscopy and dynamic light scattering. Using X-ray diffraction analysis, the MNPs were found to have an inverse spinel structure. Four MNP groups with well-selected semi-Gaussian-like diameter distributions were obtained, with measured T₂ relaxivities (r₂) at 4.7 T and room temperature in the range of 60 to 300 mM⁻¹s⁻¹, depending on the particle size. This size regulation method has great promise for applications that require homogeneous-sized MNPs made by an aqueous solution coprecipitation method. Any group of the CoFe₂O₄ MNPs could be used as initial base cores of MRI T₂ CAs, with almost unique T₂ relaxivity owing to size regulation. The methodology reported here opens up many possibilities for biosensing applications and disease diagnosis.

PACS

75.75.Fk, 78.67.Bf, 61.46.Df     

Aptamer-modified magnetic nanoprobe for molecular MR imaging of VEGFR2 on angiogenic vasculature

Nucleic acid-based aptamers have been developed for the specific delivery of diagnostic nanoprobes. Here, we introduce a new class of smart imaging nanoprobe, which is based on hybridization of a magnetic nanocrystal with a specific aptamer for specific detection of the angiogenic vasculature of glioblastoma via magnetic resonance (MR) imaging. The magnetic nanocrystal imaging core was synthesized using the thermal decomposition method and enveloped by carboxyl polysorbate 80 for water solubilization and conjugation of the targeting moiety. Subsequently, the surface of the carboxylated magnetic nanocrystal was modified with amine-functionalized aptamers that specifically bind to the vascular growth factor receptor 2 (VEGFR2) that is overexpressed on angiogenic vessels. To assess the targeted imaging potential of the aptamer-conjugated magnetic nanocrystal for VEGFR2 markers, the magnetic properties and MR imaging sensitivity were investigated using the orthotopic glioblastoma mouse model. In in vivo tests, the aptamer-conjugated magnetic nanocrystal effectively targeted VEGFR2 and demonstrated excellent MR imaging sensitivity with no cytotoxicity.     

Magnetic resonance imaging studies of the polymerisation of methylmethacrylate

Magnetic resonance imaging has been used to spatially map the time course of the bulk polymerisation of methylmethacrylate. Both two-dimensional projection and slice-selective techniques have been employed. Image intensities give qualitative information about viscosity, reaction rates and the localised extent of polymerisation. The importance of proton relaxation measurements in drawing quantitative conclusions is stressed.     

Synthesis and characterization of Sr2+ and Gd3+ doped magnetite nanoparticles for magnetic hyperthermia and drug delivery application

Commendable efforts have been gingered towards the fight against cancer. Nevertheless, it remains a major public health concern due to its predominant cause of death globally. Given this, we synthesized two different nanoparticles, Sr²⁺ and Gd³⁺ doped magnetite for magnetic hyperthermia and drug delivery application. Based on the characterization, the diffractogram shows that only one phase related to magnetite with a crystallite size of 10 nm was formed. TEM images revealed nanoparticles of spherical shapes of approximately 12 nm. There is no difference in magnetic saturation of the as-received synthesized samples (Fe₃O₄@Sr and Fe₃O₄@Gd), while the BET-specific surface area of Fe₃O₄@Gd is 8 m² g⁻¹ higher than Fe₃O₄@Sr. The heat generation in alternating magnetic field (the magnetic hyperthermia) of Fe₃O₄@Sr functionalized with citric acid and loaded with 5- fluorouracil (Fe₃O₄@Sr@CA@5-flu) is slower than Fe₃O₄@Gd@CA@5-flu. The specific absorption rate (SAR) of Fe₃O₄@Gd@CA@5-flu, 112.0 ± 10.4 W g⁻¹ was found to be higher than that of Fe₃O₄@Sr@CA@5-flu. The thermogram shows that 11% of the drug was successfully loaded on Fe₃O₄@Gd@CA@5-flu. The release of the antitumor drug by the synthesized nanoparticle drug carriers for ovarian cancer (SKOV-3 cells) therapy showed that more than 50% of the cancer cell’s viability was reduced after 72 h of incubation. The synthesized nanoparticles demonstrated a promising drug carrier for the treatment of SKOV-3 cells.