Ultrasound-Induced Magnetic Imaging of Tumors Targeted by Biofunctional Magnetic Nanoparticles

Magnetic nanofluids (Ferrofluids): Recent advances, applications, challenges, and future directions

Impelled by the need to find solutions to new challenges of modern technologies new materials with unique properties are being explored. Among various new materials that emerged over the decades, magnetic fluids exhibiting interesting physiochemical properties (optical, thermal, magnetic, rheological, apparent density, etc.) under a magnetic stimulus have been at the forefront of research. In the initial phase, there has been a fervent scientific curiosity to understand the field-induced intriguing properties of such fluids but later a plethora of technological applications emerged. Magnetic nanofluid, popularly known as ferrofluid, is a colloidal suspension of fine magnetic nanoparticles, has been at the forefront of research because of its magnetically tunable physicochemical properties and applications. Due to their stimuli-responsive behaviour, they have been finding more applications in biology and other engineering disciplines in recent years. Therefore, a critical review of this topic highlighting the necessary background, the potential of this material for emerging technologies, and the latest developments is warranted. This review also provides a summary of various applications, along with the key challenges and future research directions. The first part of the review addresses the different types of magnetic fluids, the genesis of magnetic fluids, their synthesis methodologies, properties, and stabilization techniques are discussed in detail. The second part of the review highlights the applications of magnetic nanofluids and nanoemulsions (as model systems) in probing order-disorder transitions, scattering, diffraction, magnetically reconfigurable internal structures, molecular interaction, and weak forces between colloidal particles, conformational changes of macromolecules at interfaces and polymer-surfactant complexation at the oil-water interface. The last part of the review summarizes the interesting applications of magnetic fluids such as heat transfer, sensors (temperature, pH, urea detection, cations, defect detection sensors), tunable optical filters, removal of dyes, dynamic seals, magnetic hyperthermia-based cancer therapy and other biomedical applications. The applications of magnetic nanofluids in diverse disciplines are growing day by day, yet there are challenges in their practical adaptation as field-worthy or packaged products. This review provides a pedagogical description of magnetic fluids, with the necessary background, key concepts, physics, experimental protocols, design of experiments, challenges and future directions.

Synthesised Conductive/Magnetic Composite Particles for Magnetic Ablations of Tumours

Ablation is a clinical cancer treatment, but some demands are still unsatisfied, such as electromagnetic interferences amongst multiple ablation needles during large tumour treatments. This work proposes a physical synthesis for composite particles of biocompatible iron oxide particles and liquid metal gallium (Ga) with different alternative-current (AC)-magnetic-field-induced heat mechanisms of magnetic particle hyperthermia and superior resistance heat. By some imaging, X-ray diffraction, and vibrating sample magnetometer, utilised composite particles were clearly identified as the cluster of few iron oxides using the small weight ratio of high-viscosity liquid metal Ga as conjugation materials without surfactants for physical targeting of limited fluidity. Hence, well penetration inside the tissue and the promotion rate of heat generation to fit the ablation requirement of at least 60 °C in a few seconds are achieved. For the injection and the post-injection magnetic ablations, the volume variation ratios of mice dorsal tumours on Day 12 were expressed at around one without tumour growth. Its future powerful potentiality is expected through a percutaneous injection.

Highly efficient magnetic ablation and the contrast of various imaging using biocompatible liquid-metal gallium

Background

Although the powerful clinical effects of radiofrequency and microwave ablation have been established, such ablation is associated with several limitations, including a small ablation size, a long ablation time, the few treatment positioning, and biosafety risks. To overcome these limitations, biosafe and efficient magnetic ablation was achieved in this study by using biocompatible liquid gallium as an ablation medium and a contrast medium for imaging.

Results

Magnetic fields with a frequency (f) lower than 200 kHz and an amplitude (H) × f value lower than 5.0 × 10⁹ Am⁻¹ s⁻¹ were generated using the proposed method. These fields could generate an ablation size of 3 cm in rat liver lobes under a temperature of approximately 300 °C and a time of 20 s. The results of this study indicate that biomedical gallium can be used as a contrast medium for the positioning of gallium injections and the evaluation of ablated tissue around a target site. Liquid gallium can be used as an ablation medium and imaging contrast medium because of its stable retention in normal tissue for at least 3 days. Besides, the high anticancer potential of gallium ions was inferred from the self-degradation of 100 µL of liquid gallium after around 21 days of immersion in acidic solutions.

Conclusions

The rapid wireless ablation of large or multiple lesions was achieved through the simple multi-injection of liquid gallium. This approach can replace the currently favoured procedure involving the use of multiple ablation probes, which is associated with limited benefits and several side effects.

Methods

Magnetic ablation was confirmed to be highly efficient by the consistent results obtained in the simulation and in vitro tests of gallium and iron oxide as well as the electromagnetic specifics and thermotherapy performance comparison detailed in this study Ultrasound imaging, X-ray imaging, and magnetic resonance imaging were found to be compatible with the proposed magnetic ablation method. Self-degradation analysis was conducted by mixing liquid gallium in acidic solutions with a pH of approximately 5–7 (to imitate a tumour-containing microenvironment). X-ray diffraction was used to identify the gallium oxides produced by degraded gallium ions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12938-022-01003-9.

Magnetic mediators for ultrasound theranostics

The theranostics paradigm is based on the concept of combining therapeutic and diagnostic modalities into one platform to improve the effectiveness of treatment. Combinations of multiple modalities provide numerous medical advantages and are enabled by nano- and micron-sized mediators. Here we review recent advancements in the field of ultrasound theranostics and the use of magnetic materials as mediators. Several subdisciplines are described in detail, including controlled drug delivery and release, ultrasound hyperthermia, magneto-ultrasonic heating, sonodynamic therapy, magnetoacoustic imaging, ultrasonic wave generation by magnetic fields, and ultrasound tomography. The continuous progress and improvement in theranostic materials, methods, and physical computing models have created undeniable possibilities for the development of new approaches. We discuss the prospects of ultrasound theranostics and possible expansions of other studies to the theranostic context.

Functionalized Co2FeAl Nanoparticles for Detection of SARS CoV-2 Based on Reverse Transcriptase Loop-Mediated Isothermal Amplification

Loop-mediated isothermal amplification (LAMP) is a sensitive, efficient, and rapid nucleic acid amplification technique resulting in a large number of amplicons; however, it suffers from a high incidence of false positives due to carry-over and aerosol. Herein, we report a 10 min nano-capture system that is used in conjunction with a modified reverse transcriptase-LAMP (RT-LAMP) assay for the accurate detection of SARS CoV-2 virus. The nano-capture system employs in-house-designed probe-functionalized magnetic nanoparticles Co2FeAl (cobalt-based Heusler alloy) for efficient capture of contaminating amplicons from the reaction mixture preceding RT-LAMP. The nano-cleaned RT-LAMP assay along with engineered primers successfully detected the presence of 10 copies of SARS CoV-2 virus while completely eliminating the incidence of false positives. The presented contaminant-capture method has been compared with other approaches for elimination of contaminants and was found to be more effective. The insight brought in this work is the design of a rapid nano-capture system that hybridizes with contaminating amplicons (carry-over) with high specificity to enable easy removal from the assay for elimination of false positives. The method has been proven to be successful for RT-LAMP assays in the rapid and highly specific detection of SARS CoV-2, which is currently a major challenge for global health. To the best of our knowledge, this is the first work involving a nano-based cleaning strategy for reliable and rapid diagnosis using isothermal amplification approaches.

Recent Advancements of Specific Functionalized Surfaces of Magnetic Nano- and Microparticles as a Theranostics Source in Biomedicine

Magnetic nano- and microparticles (MNMPs) belong to a highly versatile class of colloids with actuator and sensor properties that have been broadly studied for their application in theranostics such as molecular imaging and drug delivery. The use of advanced biocompatible, biodegradable polymers and polyelectrolytes as MNMP coating materials is essential to ensure the stability of MNMPs and enable efficient drug release while at the same time preventing cytotoxic effects. In the past years, huge progress has been made in terms of the design of MNMPs. Especially, the understanding of coating formation with respect to control of drug loading and release kinetics on the molecular level has significantly advanced. In this review, recent advancements in the field of MNMP surface engineering and the applicability of MNMPs in research fields of medical imaging, diagnosis, and nanotherapeutics are presented and discussed. Furthermore, in this review the main emphasis is put on the manipulation of biological specimens and cell trafficking, for which MNMPs represent a favorable tool enabling transport processes of drugs through cell membranes. Finally, challenges and future perspectives for applications of MNMPs as theranostic nanomaterials are discussed.

Synthesis of Multiarm Peptide Dendrimers for Dual Targeted Thrombolysis

Current thrombolytic agents generally possess low specificity and pose a high risk of intracranial hemorrhage. Here, various generations of multiarm polylactic acid-polyglutamic acid peptide dendrimers were synthesized, and then nattokinase-combining magnetic Fe₃O₄ nanoparticles and RGD-modified dendrimers (Fe₃O₄-(4-PLA(G₃)₄)-RGD) were fabricated for targeted thrombi dissolution. Their in vitro and in vivo thrombolytic properties were determined. In vitro determination indicated that Fe₃O₄-(4-PLA(G₃)₄)-RGD/nattokinase provided 3-fold higher blood clot dissolution than that obtained with free nattokinase. An in vivo thrombolytic examination revealed that most of the thrombi were dissolved under an external magnetic field. In addition, there were many nanoparticles in vascular endothelial cells, demonstrating the RGD and magnetic dual targeting capacity of Fe₃O₄-(4-PLA(G₃)₄)-RGD/nattokinase. These results demonstrated that Fe₃O₄-(4-PLA(G₃)₄)-RGD nanoparticles not only will deliver targeted thrombolytic agents to enhance the efficacy of site-specific thrombolytic treatment but also have potential in the diagnosis of thrombotic disease in its early stages.

Ultra-Early Diagnosis of Acute Myocardial Infarction in Rats Using Ultrasound Imaging of Hollow Double-Layer Silica Nanospheres

Timely diagnosis of acute myocardial infarction (AMI) strongly impacts the survival rate of patients. The authors report the development of a two-shell hollow silica contrast agent useful for ultrasound (US) imaging, which is able to provide ultra-early diagnosis of AMI. To target the characterization of fast blood flow and high blood pressure in the heart, two shells of hollow silica are adopted with opposite polarities, which assemble based on amino and perfluorodecyl silanes. The external amino silane facilitates the attachment of disease-targeted groups, while the internal perfluorodecyl silane provides great US imaging contrast. The material also possesses superior water dispersity, controllable morphology, low toxicity, and biodegradability both in vitro and in vivo, thus promoting its applications in the ultra-early diagnosis of AMI in rats, and is particularly useful for delineation of myocardial necrosis sites.

pH-dependent and cathepsin B activable CaCO3 nanoprobe for targeted in vivo tumor imaging

Background: The intraoperative visualization of tumor cells is a powerful modality for surgical treatment of solid tumors. Since the completeness of tumor excision is closely correlated with the survival of patients, probes that can assist in distinguishing tumor cells are highly demanded.

Purpose: In the present study, a fluorescent probe JF1 was synthesized for imaging of tumor cells by conjugating a substrate of cathepsin B (quenching moiety) to Oregon Green derivative JF2 using a self-immolative linker.

Methods: JF1 was then loaded into the folate-PEG modified CaCO₃ nanoparticles. The folate receptor-targeted, pH-dependent, and cathepsin B activable CaCO₃ nanoprobe was test in vitro and in vivo for tumor imaging.

Results: CaCO₃ nanoprobe demonstrated good stability and fast lighting ability in tumors under low pH conditions. It also showed lower fluorescence background than the single cathepsin B dependent fluorescent probe. The pH-dependent and cathepsin B controlled “turn-on” property enables precise and fast indication of tumor in vitro and in vivo.

Conclusion: This strategy of controlled drug delivery enables in vivo imaging of tumor nodules with a high signal-to-noise ratio, which has great potential in surgical tumor treatment.

Magnetic particle mapping using magnetoelectric sensors as an imaging modality

Magnetic nanoparticles (MNPs) are a hot topic in the field of medical life sciences, as they are highly relevant in diagnostic applications. In this regard, a large variety of novel imaging methods for MNP in biological systems have been invented. In this proof-of-concept study, a new and novel technique is explored, called Magnetic Particle Mapping (MPM), using resonant magnetoelectric (ME) sensors for the detection of MNPs that could prove to be a cheap and efficient way to localize the magnetic nanoparticles. The simple and straightforward setup and measurement procedure includes the detection of higher harmonic excitations of MNP ensembles. We show the feasibility of this approach by building a measurement setup particularly suited to exploit the inherent sensor properties. We measure the magnetic response from 2D MNP distributions and reconstruct the distribution by solving the inverse problem. Furthermore, biological samples with magnetically labeled cells were measured and reconstruction of the distribution was compared with light microscope images. Measurement results suggest that the approach presented here is promising for MNP localization.

PEGylated self-assembled enzyme-responsive nanoparticles for effective targeted therapy against lung tumors

Background

Matrix-metalloproteinases, which are overexpressed in many types of cancer, can be applied to improve the bioavailability of chemotherapeutic drugs and guide therapeutic targeting. Thus, we aimed to develop enzyme-responsive nanoparticles based on a functionalized copolymer (mPEG-Peptide-PCL), which was sensitive to matrix metalloproteinase, as smart drug vesicles for enhanced biological specificity and reduced side effects.

Results

The rate of in vitro curcumin (Cur) release from Cur-P-NPs was not markedly accelerated in weakly acidic tumor microenvironment, indicating a stable intracellular concentration and a consistent therapeutic effect. Meanwhile, P-NPs and Cur-P-NPs displayed prominent biocompatibility, biostability, and inhibition efficiency in tumor cells. In addition, Cur-P-NPs showed higher fluorescence intensity than Cur-NPs in tumor cells, implying enhanced cell permeability and targeting ability. Moreover, the internalization and intracellular transport of Cur-P-NPs were mainly via macropinocytosis. Studies of pharmacodynamics and cellular uptake in vitro and biodistribution in vivo demonstrated that Cur-P-NPs had stronger target efficiency and therapeutic effect than Cur-DMSO and Cur-NPs in tumor tissue.

Conclusion

Results indicate that Cur-P-NPs can be employed for active targeted drug delivery in cancer treatment and other biomedical applications.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0384-8) contains supplementary material, which is available to authorized users.

Fabrication of multifunctional ferric oxide nanoparticles for tumor-targeted magnetic resonance imaging and precise photothermal therapy with magnetic field enhancement

In this study, a biocompatible nanotheranostic platform (termed as Fe₂O₃@PDA-affibody) has been constructed on the basis of coating a near-infrared light (NIR)-absorbing polydopamine (PDA) shell on oleic acid-capped superparamagnetic ferric oxide nanoparticles (Fe₂O₃ NPs) using the water-in-oil microemulsion method and then conjugated with affibody Z_IGF1R:4551, a peptide with high affinity to tumor and a polyethylene glycol (PEG) stabilizer. The Fe₂O₃@PDA-affibody integrates T₂-weighted magnetic resonance imaging (MRI), tumor-targeting, and magnetic field (MF)-enhanced photothermal therapy (PTT) functionalities into an all-in-one system. The Fe₂O₃@PDA-affibody shows high negative contrast in the MRI of an SW620 tumor bearing mouse with a decrease of 68% MRI signal, indicating that the Fe₂O₃@PDA-affibody can recognize tumor with high efficacy and specificity. Furthermore, a high accumulation ratio (>13.5% ID g^-1) and enhanced inhibition of tumor growth are achieved under near-infrared (NIR) (808 nm) laser irradiation with the aid of an external MF focused on the targeted tumor, resulting in complete eradication of mouse-borne SW620 tumors without regrowth.