Multifunctional Ultrasound Contrast Agents Research Articles

A new PLA-Tween composited drug-carrying C60-Fe3O4 multifunctional ultrasound contrast agent based on three kinds of lesions.

A PLA–Tween composited drug-carrying C60–Fe3O4 microbubble was designed and prepared. Using Fe3O4 as a targeting factor and C60 as a drug carrier, warfarin (WF), netimixin (NET) and doxorubicin (DOX) respectively were loaded on a C60–Fe3O4 complex through π–π conjugate effect, and C60–Fe3O4–WF, C60–Fe3O4–NET and C60–Fe3O4–DOX targeted drug-loading complexes were obtained. The three drug-loading complexes were respectively combined into PLA and Tween membrane material, PLA–Tween composited C60–Fe3O4–DOX microbubbles, PLA–Tween composited C60–Fe3O4–NET microbubbles and PLA–Tween composited C60–Fe3O4–WF microbubbles were obtained, respectively. The average particle size of PLA–Tween composited drug-carrying C60–Fe3O4 microbubbles was 446.4 nm, the microbubble size was uniform, and the Zeta potential was −40.5 mV which showed a good stability. The loading rates of DOX, NET and WF in PLA–Tween composited drug-carrying C60–Fe3O4 microbubbles were 5.58%, 8.15% and 3.37%, respectively. PLA–Tween composited C60–Fe3O4–DOX microbubbles could inhibit the breast cancer MDA-MB-231 cells and normal mouse fibroblast 3T3 cells, the inhibition rates were respectively 53.4% and 18.6%, which significantly reduced the toxicity of free DOX drug on the normal cells (62.2%). PLA–Tween composited C60–Fe3O4–NET microbubbles had a inhibitory effect on the growth of Staphylococcus aureus and Escherichia coli, and the inhibitory effect on Escherichia coli was better. PLA–Tween composited C60–Fe3O4–WF microbubbles could inhibit the formation of thrombus, and PT, TT and APTT were significantly prolonged. PLA–Tween composited C60–Fe3O4 microbubbles had a developing effect on the kidney, bladder and abdominal aorta of rabbit. Under the action of external magnetic field, the ultrasonic imaging effect of composite microbubbles was significantly enhanced.

Novel Span-PEG Multifunctional Ultrasound Contrast Agent Based on CNTs as a Magnetic Targeting Factor and a Drug Carrier.

Based on the targeting of ferroferric oxide (Fe3O4) and the drug-loading property of carbon nanotubes (CNTs), a novel Span-PEG-composited Fe3O4–CNTs–DOX multifunctional ultrasound contrast agent was designed and applied to tumor lesions. In situ liquid phase synthesis was employed to prepare the Fe3O4–CNTs magnetic targeting complex, and the physical method was used to obtain the Fe3O4–CNTs–DOX complex by loading doxorubicin (DOX) onto Fe3O4–CNTs. The targeted drug-loading complex Fe3O4–CNTs–DOX was combined with the membrane material of Span-PEG by the acoustic vibration cavitation method. The maximum tolerance for Span-PEG-composited Fe3O4–CNTs–DOX microbubbles was 450 times higher, which has good safety. The loading rate of DOX in the obtained composite microbubbles was 17.02%. The proliferation inhibition rate of Span-PEG-composited Fe3O4–CNTs–DOX microbubbles on liver cancer SMMC-7721 cells reached 48.3%. Span-PEG-composited Fe3O4–CNTs–DOX microbubbles could significantly enhance ultrasonic imaging and enrich at a specific location under an external magnetic field, and the extended imaging time could ensure the effective observation and diagnosis of lesions.

New Span-PEG-composited Fe3O4-CNT as a multifunctional ultrasound contrast agent for inflammation and thrombotic niduses.

By attaching ferroferric oxide (Fe3O4) to drug-carrying carbon nanotubes (CNTs), we generated a new Span-PEG composite with Fe3O4-CNT multifunctional microbubbles for inflammation and thrombus niduses. The Fe3O4-CNT magnetic targeting complex was prepared by in situ synthesis, and then acetylsalicylic acid (ASA) and gentamicin (GM) were loaded onto the Fe3O4-CNT complex by physical methods to produce Fe3O4-CNT-ASA and Fe3O4-CNT-GM complexes, respectively. Span-PEG-composited Fe3O4-CNT-ASA or Fe3O4-CNT-GM microbubbles were synthesized with Span and PEG as the membrane materials by the acoustic cavitation method. The obtained composite microbubbles were smooth, hollow spheres with an average particle size of 425 nm. The ASA and GM loading rates in Span-PEG-composited Fe3O4-CNT-ASA and Fe3O4-CNT-GM microbubbles were 1.12% and 19.05%, respectively. Span-PEG-composited Fe3O4-CNT-ASA microbubbles inhibited thrombosis and demonstrated an anticoagulation effect in vitro. Additionally, Span-PEG-composited Fe3O4-CNT-ASA microbubbles showed significantly enhanced ultrasound imaging of rabbit abdominal aorta and extended the signal time under the action of an external magnetic field. Thus, Span-PEG-composited Fe3O4-CNT-GM microbubbles inhibited Escherichia coli and Staphylococcus aureus, enhanced the ultrasound imaging of rabbit abdominal uterus and had better stability and fluidity.

The Performance of Composite Nanoparticles Based on Fe3O4@SiO2/PLGA/PFOB in Magnetic Resonance Imaging and Photoacoustic Imaging

Polylactic acid glycolic acid (PLGA), a polymer material, is used as a shell and perfluorooctane (PFOB) as the core. Fe3O4@SiO2 nanoparticles are distributed in the shell to prepare a magnetic phase change multifunctional nano emulsion contrast agent (Fe3O4@SiO2/PLGA/PFOB). The ultrasound, magnetic resonance imaging and CT imaging effects of the contrast agent on normal rat liver parenchyma are investigated. Methods: Single emulsification method is used to prepare Fe3O4@SiO2-loaded polymer Fe3O4@SiO2/PLGA/PFOB nanoparticles encapsulated with PLGA. In addition, polymer Fe3O4@SiO2/PLGA nanoparticles loaded with Fe3O4@SiO2 nanoparticles, PLGA@PFOB nanoparticles coated with PLGA and blank PLGA nanoparticles are prepared as experimental control group. Its surface morphology, internal structure, particle size, potential and other general characteristics are tested. RAW264.7 mouse mononuclear macrophages are cultured in vitro. Prussian blue staining is used to observe macrophage phagocytosis after Fe3O4@SiO2/PLGA/PFOB contrast agent is added to incubate for 3 hours. MTT method is used to detect the effect of contrast agent on cell activity. The macrophage suspension engulfed with Fe3O4-PFOB is examined by ultrasound, magnetic resonance and CT. The results showed that Fe3O4@SiO2/PLGA/PFOB is brown emulsion after being dissolved in double distilled water. Under the light microscope and scanning electron microscope, Fe3O4@SiO2/PLGA/PFOB is spherical, with regular shape, uniform size, good dispersity and smooth surface. Macrophages are dependent on the phagocytosis of the contrast medium without affecting the activity of macrophages. Moreover, in vitro imaging experiments, compared with the control group, macrophages phagocytized by Fe3O4@SiO2/PLGA/PFOB have obvious enhancement effects in ultrasound, magnetic resonance and CT imaging. In conclusion, Fe3O4@SiO2/PLGA/PFOB has good stability in vivo, can be engulfed by liver macrophages, and can enhance ultrasound, magnetic resonance and CT imaging of liver parenchyma. It is a safe and effective multifunctional ultrasound contrast agent.

Indocyanine green (ICG) – Menthol loaded cerasomal nanoparticles for ultrasound imaging and photothermal therapy against tumor

Abstract Multifunctional ultrasound contrast agents (UCAs) combining ultrasonic diagnosis with tumor therapy have received enormous attentions in virtue of their good biocompatibility and high biological penetration ability. However, nanoscale UCAs with suitable size and good therapeutic effect remain to be developed in future studies. Herein, indocyanine green and L-menthol loaded hybrid cerasomes (ICG-MCNs) was fabricated as a multifunctional theranostic nanoplatform, which exhibited high structure stability and photo-stability in aqueous. Mutual assistance with the photothermal effect of ICG, heating triggered tri-phase transition of L-menthol could produce continuous gas microbubbles for enhanced ultrasound imaging. Thus, the resultant ICG-MCNs is anticipated to be a competent candidate for US imaging and photothermal therapy.

New Polylactic Acid Multifunctional Ultrasound Contrast Agent Based on Graphene Oxide as the Carrier of Targeted Factor and Drug Delivery.

In recent years, the development of ultrasound contrast agents has encouraged their use as a drug system for diagnosis and therapy. In this paper, polylactic acid (PLA) composite microbubbles (FA/DOX/GO/DOX/PLA) were prepared with graphene oxide (GO) as a carrier of the targeted factor folic acid (FA) and doxorubicin (DOX) by the multiple emulsification–solvent evaporating process. Appearance, particle size, and zeta potential of PLA composite microbubbles were characterized by using a nanoparticle size analyzer and transmission electron microscopy. Breast cancer cells MCF-7 were used to evaluate the antitumor activity of PLA composite microbubbles in vitro by using the CCK-8 and acridine orange staining method. The ultrasonic imaging effect of PLA composite microbubbles was investigated in New Zealand white rabbits by the Doppler color ultrasound imaging system. With Kunming mice as the research model, the acute toxicity of PLA composite microbubbles was examined. The experimental results showed that the prepared PLA composite microbubbles presented a hollow and spherical shape with a particle size of 600 nm or so and a zeta potential of −37.5 ± 10.0 mV. They had a good effect of the enhancing imaging, and clear ultrasound imaging can be obtained. PLA composite microbubbles showed a significant proliferation inhibition effect on breast cancer cells MCF-7 in a dose-dependent manner. After PLA composite microbubbles were modified by FA, they were good for targeting FA receptors on the surface of MCF-7 cells, which increased the inhibition rate of the tumor cells. LD50 of PLA composite microbubbles was 87.529 mg·kg–1; the mice did not show the acute toxicity when the dose of composite microbubbles was lower than this value.

Targeted Soft Biodegradable Glycine/PEG/RGD-Modified Poly(methacrylic acid) Nanobubbles as Intelligent Theranostic Vehicles for Drug Delivery.

The development of multifunctional ultrasound contrast agents has inspired considerable interest in the application of biomedical imaging and anticancer therapeutics. However, combining multiple components that can preferentially accumulate in tumors in a nanometer scale poses one of the major challenges in targeting drug delivery for theranostic application. Herein, reflux-precipitation polymerization, and N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide-meditated amidation reaction were introduced to effectively generate a new type of soft glycine/poly(ethylene glycol) (PEG)/RGD-modified poly(methacrylic acid) nanobubbles with a uniform morphology and desired particle size (less than 100 nm). Because of the enhanced biocompatibility resulting from the glycine modification, over 80% of the cells survived, even though the dosage of glycine-modified polymeric nanobubbles was up to 5 mg/mL. By loading doxorubicin as an anticancer drug and perfluorohexane as an ultrasound probe, the resulting glycine/PEG/RGD-modified nanobubbles showed remarkable cancer therapeutic efficacy and a high quality of ultrasonic imaging; thus, the ultrasonic signal exhibited a 1.47-fold enhancement at the tumor site after intravenous injection. By integrating diagnostic and therapeutic functions into a single nanobubble, the new type of theranostic nanobubbles offers a promising strategy to monitor the therapeutic effects, giving important insights into the ultrasound-traced and enhanced targeting drug delivery in biomedical applications.

Targeting property and toxicity of a novel ultrasound contrast agent microbubble carrying the targeting and drug-loaded complex FA-CNTs-PTX on MCF7 cells

The application of ultrasound contrast agents not only is confined to the enhancement of ultrasound imaging but also has started to be used as a drug system for diagnosis and treatment. In this paper, Span60 and PEG1500 were used as membrane materials, and a new targeting and drug-loading multifunctional ultrasound contrast agent microbubble enveloping the FA-CNTs-PTX complex was successfully prepared by acoustic cavitation. With the breast cancer cell line MCF7 as the research target, the effects of the microbubble with FA-CNTs-PTX on the proliferation and toxicity of MCF7 cells were studied using a CCK-8 and AO/EB double-staining method. The influences of the microbubbles with FA-CNTs-PTX on the cellular morphology and apoptosis period of the MCF7 cells were detected using an inverted fluorescence microscope. The apoptosis of MCF7 cells induced by the microbubbles with FA-CNTs-PTX was investigated with flow cytometry and an annexin and PI double staining fluorescence quantitative analysis. The results indicated that the ultrasound contrast agent microbubble with FA-CNTs-PTX remarkably inhibited the proliferation of MCF7 cells, which was mainly controlled by the drug loading rate and the nanometer size of the microbubbles. Moreover, the proliferative inhibition rate of the microbubbles with FA-CNTs-PTX was related to the cell apoptosis period of MCF7 cells. Its inhibition degree on the proliferation of MCF7 cells was higher than that of the hepatoma HepG2 cells. The apoptosis rate of MCF7 cells induced by the microbubbles with FA-CNTs-PTX was higher than that of normal human umbilical vein endothelial cells (HUVECs), and the microbubbles with FA-CNTs-PTX could target the MCF7 cells.

Ultrasound-Based Multimodal Molecular Imaging and Functional Ultrasound Contrast Agents

Ultrasound-based multimodal molecular imaging and functional ultrasound contrast agents (UCAs) have garnered great interest in biomedical imaging over the past few years. With the rapid development of molecular imaging technique, UCAs with single-function and single imaging modality can no longer satisfy increasingly growing medical diversification and hominization demand. The device of functional UCAs including multimodality and multifunction is of great value for disease diagnosis, treatment and research, and greatly accelerate the development of ultrasound-based multimodal molecular imaging. Functional UCAs can not only be applied for multimodality imaging to compensate for the disadvantages of each imaging modality whilst taking advantage of their individual strengths to acquire more biological information, but also can act as a vector carrying drugs or therapeutic genes to accomplish the combination of diagnosis and treatment, which is an existing study hotspot and has achieved initiatory success. In this paper, we reviewed the advances of ultrasound-based multimodal imaging, multimodal and multifunctional UCAs.

Advancement of Targeted Ultrasound Contrast Agents and their Applications in Molecular Imaging and Targeted Therapy

In recent years, targeted ultrasound contrast agents (UCA) have emerged with the rapid development of contrast-enhanced ultrasound technology and bio-nanotechnology, showing good prospects for applications in molecular imaging and targeted therapy. The non-invasive treatment modality can reduce the drug dosage, toxicity and side effects, providing a new kind of methodology and approach for treatments, which will greatly expand the research and its applications. Targeted UCA have been developed rapidly in recent years, and a variety of new UCA appear, such as multi-functional UCA, multi-modal UCA, UCA with double ligands or more ligands, long-circulating UCA and immune type UCA, which meet growing clinical and research needs. The novel UCA have made a great progress and play an increasingly important role in molecular imaging. In this article, we reviewed the concepts of ultrasound molecular imaging, and summarized the applications of targeted UCA in molecular imaging and targeted therapy.

A general strategy for obtaining biodegradable polymer shelled microbubbles as theranostic devices

Fabrication of multifunctional ultrasound contrast agents (UCAs) has been recently addressed by several research groups. A versatile strategy for the synthesis of UCA precursors in the form of biodegradable vesicles with a biocompatible crosslinked polymer shell is described. Upon ultrasound irradiation, acoustic droplet vaporization transforms such particles into microbubbles behaving as UCAs. This proof of concept entails the features of a potential theranostic microdevice.

Stability of Echogenic Liposomes as a Blood Pool Ultrasound Contrast Agent in a Physiologic Flow Phantom

Echogenic liposomes (ELIP) are multifunctional ultrasound contrast agents (UCAs) with a lipid shell encapsulating both air and an aqueous core. ELIP are being developed for molecular imaging and image-guided therapeutic delivery. Stability of the echogenicity of ELIP in physiologic conditions is crucial to their successful translation to clinical use. In this study, we determined the effects of the surrounding media's dissolved air concentration, temperature transition and hydrodynamic pressure on the echogenicity of a chemically modified formulation of ELIP to promote stability and echogenicity. ELIP samples were diluted in porcine plasma or whole blood and pumped through a pulsatile flow system with adjustable hydrodynamic pressures and temperature. B-mode images were acquired using a clinical diagnostic scanner every 5 s for a total duration of 75 s. Echogenicity in porcine plasma was assessed as a function of total dissolved gas saturation. ELIP were added to plasma at room temperature (22 °C) or body temperature (37 °C) and pumped through a system maintained at 22 °C or 37 °C to study the effect of temperature transitions on ELIP echogenicity. Echogenicity at normotensive (120/80 mmHg) and hypertensive pressures (145/90 mmHg) was measured. ELIP were echogenic in plasma and whole blood at body temperature under normotensive to hypertensive pressures. Warming of samples from room temperature to body temperature did not alter echogenicity. However, in plasma cooled rapidly from body temperature to room temperature or in degassed plasma, ELIP lost echogenicity within 20 s at 120/80 mmHg. The stability of echogenicity of a modified ELIP formulation was determined in vitro at body temperature, physiologic gas concentration and throughout the physiologic pressure range. However, proper care should be taken to ensure that ELIP are not cooled rapidly from body temperature to room temperature as they will lose their echogenic properties. Further in vivo investigations will be needed to evaluate the optimal usage of ELIP as blood pool contrast agents.

Multi-functional ultrasound contrast agents for in vitro ultrasound/MR dual-mode imaging and high-intensity focused ultrasound synergism

Objective To prepare the multi-functional ultrasound contrast agents,which were investigated for ultrasound(US)/MR dual-mode imaging and high-intensity focused ultrasound(HIFU)synergism in vitro.Methods Double emulsion method was used to prepare the superparamagnetic iron oxide(SPIO)-loaded PLGA microcapsules(s-PLGA),and its morphology,size,Fe3O4 loading capacity were assessed.Then,the prepared s-PLGA microcapsules with different concentrations were applied to perform ultrasound and MR imaging in vitro.In addition,the degassed bovine liver in vitro was directly injected into 200 μl s-PLGA in saline(0.5 mg Fe/ml)just before HIFU ablation,the saline(200 μl)and pure PLGA (200 μl)were employed for control.After HIFU ablation,the volume of coagulated tissue irradiated by HIFU was calculated.Results The s-PLGA microcapsules were observed with regular spherical morphology and its average size was(885.6 ± 133.2)nm.In vitro,the s-PLGA showed hyperechogenicity in US imaging and MR negatively enhanced effeet in T2WI,the volume of coagulated tissue irradiated by HIFU after local injection of s-PLGA was larger than that of saline and pure PLGA(P＜0.05).Conclusions The prepared s-PLGA microcapsules are successfully acted as dual-mode biological imaging contrast agents for ultrasound and MR imaging and HIFU synergism in vitro. Key words: Ultrasonography; Microbubbles; Nanotechnology; Magnetic resonance imaging; Ultrasound,high-intensity focused