A Highly Efficient One-for-All Nanodroplet for Ultrasound Imaging-Guided and Cavitation-Enhanced Photothermal Therapy

The hybrid nanosystem for the identification and magnetic hyperthermia immunotherapy of metastatic sentinel lymph nodes as a multifunctional theranostic agent

Lymphatic metastasis is the main cause of early-stage tumor spread, making the identification and therapy of metastatic sentinel lymph nodes (SLNs) are highly desirable in clinic. Currently, suspected malignant SLNs typically undergo a series of independent operations in clinical practice, including imaging, staining, sentinel lymph node biopsy (SLNB) and lymph node dissection (LND), which brings inconvenience to diagnosis and treatment, and may cause postoperative complications for patients. Moreover, the ordinary removal of tumor-draining lymph nodes (TDLNs) may do harm to systemic immunity required for tumor eradication. Hence, we utilized the hybrid nanosystem (SPIOs + RPPs) we constructed before for the integrated staining, ultrasound imaging, and therapy of metastatic SLNs. In this study, SPIOs + RPPs could migrate into SLNs successfully to stain them black for easy visual identification. Beyond staining, the hybrid nanosystem could realize contrast enhanced ultrasound (CEUS) imaging in SLNs. Meanwhile, it could inhibit cancer cells to lower the tumor burden and reverse immune-suppressive microenvironment of metastatic SLNs effectively via magnetic hyperthermia immunotherapy in VX2 tumor-bearing rabbits with popliteal fossa lymph node metastasis. These findings indicate that SPIOs + RPPs is a potential multifunctional theranostic agent for detection and therapy of lymphatic metastasis.

Nanomaterials for Ultrasound Imaging- Guided Sonodynamic Therapy

Ultrasound examination is becoming the most popular medical imaging modality because of its low cost and high safety profile. Ultrasound contrast agents enhance the scattering of sound waves, which can improve the clarity and resolution of images. Nanoparticle Ultrasound contrast agents have the characteristics of a large specific surface area and a modifiable surface, which can increase drug loading capacity, prolong circulation time, and enable drug enrichment in specific organs or tissues. This leads to improved therapeutic effects and reducing toxic and side effects. Compared with traditional ultrasound contrast agents, Nano-ultrasound contrast agents overcome the limitation of imaging solely within blood vessels and facilitate imaging within tumor tissues, thereby extending the duration of enhanced imaging. Sonodynamic therapy is an emerging treatment method that has been developed rapidly in recent years, which has the advantages of noninvasive, high spatial and temporal resolution, and low toxicity and side effects. Sonodynamic therapy utilizes a sonosensitizer that, when excited by ultrasound at the tumor site, produces toxic reactive oxygen species, inducing apoptosis or necrosis in tumor cells. Ultrasound-guided sonodynamic therapy allows for real-time observation of lesions, is convenient and flexible, and is free of radiation exposure. With the use of nanomaterials as carriers, ultrasound-guided sonodynamic therapy has made significant strides. This study categorizes and summarizes the current research on acoustic sensitizer carrier materials, including carbon-based, silicon-based, peptide-based, iron-based, metal-organic frameworks, polymers, and liposomes. It concludes by highlighting the current challenges in the integration of ultrasound imaging with sonodynamic therapy and suggests future directions for clinical application development.

Ultrasound-controlled nano oxygen carriers enhancing cell viability in 3D GelMA hydrogel for the treatment of myocardial infarction

Heart failure is a critical and ultimate phase of cardiovascular ailment that leads to a considerable incidence of disability and mortality. Among various factors contributing to heart failure, myocardial infarction is one of the most frequent and significant causes, which is still difficult to manage effectively. An innovative therapeutic strategy, namely a 3D bio-printed cardiac patch, has recently emerged as a promising approach to substitute damaged cardiomyocytes in a localized infarct region. Nevertheless, the efficacy of this treatment primarily relies on the long-term viability of the transplanted cells. In this study, we aimed to construct acoustically sensitive nano oxygen carriers to improve cell survival inside the bio-3D printed patch. In this study, we initially created nanodroplets capable of phase transition triggered by ultrasound and integrated them into GelMA (Gelatin Methacryloyl) hydrogels, which were then employed for 3D bioprinting. After adding nanodroplets and ultrasonic irradiation, numerous pores appeared inside the hydrogel with improved permeability. We further encapsulated hemoglobin into nanodroplets (ND-Hb) to construct oxygen carriers. Results of in vitro experiments showed the highest cell survival within the patch of ND-Hb irradiated by the low-intensity pulsed ultrasound (LIPUS) group. The genomic analysis discovered that the increased survival of seeded cells within the patch might be related to the protection of mitochondrial function owing to the improved hypoxic state. Eventually, in vivo studies revealed that the LIPUS+ND-Hb group had improved cardiac function and increased revascularization after myocardial infarction. To summarize, our study successfully improved the permeability of the hydrogel in a non-invasive and efficient manner, facilitating the exchange of substances in the cardiac patch. Moreover, ultrasound-controlled oxygen release augmented the viability of the transplanted cells and expedited the repair of infarcted tissues.

Phase-transition nanodroplets with immunomodulatory capabilities for potentiating mild magnetic hyperthermia to inhibit tumour proliferation and metastasis

BACKGROUND

Magnetic hyperthermia (MHT)-mediated thermal ablation therapy has promising clinical applications in destroying primary tumours. However, traditional MHT still presents the challenges of damage to normal tissues adjacent to the treatment site and the destruction of tumour-associated antigens due to its high onset temperature (> 50 °C). In addition, local thermal ablation of tumours often exhibits limited therapeutic inhibition of tumour metastasis.

RESULTS

To address the above defects, a hybrid nanosystem (SPIOs + RPPs) was constructed in which phase transition nanodroplets with immunomodulatory capabilities were used to potentiate supermagnetic iron oxide nanoparticle (SPIO)-mediated mild MHT (< 44 °C) and further inhibit tumour proliferation and metastasis. Magnetic-thermal sensitive phase-transition nanodroplets (RPPs) were fabricated from the immune adjuvant resiquimod (R848) and the phase transition agent perfluoropentane (PFP) encapsulated in a PLGA shell. Because of the cavitation effect of microbubbles produced by RPPs, the temperature threshold of MHT could be lowered from 50℃ to approximately 44℃ with a comparable effect, enhancing the release and exposure of damage-associated molecular patterns (DAMPs). The exposure of calreticulin (CRT) on the cell membrane increased by 72.39%, and the released high-mobility group B1 (HMGB1) increased by 45.84% in vivo. Moreover, the maturation rate of dendritic cells (DCs) increased from 4.17 to 61.33%, and the infiltration of cytotoxic T lymphocytes (CTLs) increased from 10.44 to 35.68%. Under the dual action of mild MHT and immune stimulation, contralateral and lung metastasis could be significantly inhibited after treatment with the hybrid nanosystem.

CONCLUSION

Our work provides a novel strategy for enhanced mild magnetic hyperthermia immunotherapy and ultrasound imaging with great clinical translation potential.

Microbubbles for human diagnosis and therapy

Microbubbles (MBs) were observed for the first time in vivo as a curious consequence of quick saline injection during ultrasound (US) imaging of the aortic root, more than 50 years ago. From this serendipitous event, MBs are now widely used as contrast enhancers for US imaging. Their intrinsic properties described in this review, allow a multitude of designs, from shell to gas composition but also from grafting targeting agents to drug payload encapsulation. Indeed, the versatile MBs are deeply studied for their dual potential in imaging and therapy. As presented in this paper, new generations of MBs now opens perspectives for targeted molecular imaging along with the development of new US imaging systems. This review also presents an overview of the different therapeutic strategies with US and MBs for cancer, cardiovascular diseases, and inflammation. The overall aim is to overlap those fields in order to find similarities in the MBs application for treatment enhancement associated with US. To conclude, this review explores the new scales of MBs technologies with nanobubbles development, and along concurrent advances in the US imaging field. This review ends by discussing perspectives for the booming future uses of MBs.

Nanoparticle-mediated therapeutic management in cholangiocarcinoma drug targeting: Current progress and future prospects

Patients with cholangiocarcinoma (CCA) often have an unfavorable prognosis because of its insidious nature, low resectability rate, and poor response to anticancer drugs and radiotherapy, which makes early detection and treatment difficult. At present, CCA has a five-year overall survival rate (OS) of only 5%, despite advances in therapies. New an increasing number of evidence suggests that nanoplatforms may play a crucial role in enhancing the pharmacological effects and in reducing both short- and long-term side effects of cancer treatment. This document reviews the advantages and shortcomings of nanoparticles such as liposomes, polymeric nanoparticle，inorganic nanoparticle, nano-metals and nano-alloys, carbon dots, nano-micelles, dendrimer, nano-capsule, bio-Nanomaterials in the diagnosis and treatment of CCA and discuss the current challenges in of nanoplatforms for CCA.

Phospholipid-mimicking block, graft, and block-graft copolymers for phase-transition microbubbles as ultrasound contrast agents

Background: Lipid and polymer microbubbles (MBs) are widely used as ultrasound contrast agents in clinical diagnosis, and possess great potential in ultrasound-mediated therapy due to their drug loading function. However, overcoming the limitations of stability and echo enhancement of MBs are still a considerable challenge.

Methods: A series novel block, graft and block-graft copolymers was proposed and prepared in this work, and these copolymers were used as shells to encapsulate perfluoropentane as ultrasound contrast agents. First, block, graft and block-graft copolymers with different topological structures were prepared. Then, these copolymers were prepared into block copolymer phase-transition MBs, graft copolymer phase-transition MBs, and block-graft copolymer phase-transition MBs, respectively. Finally, the dexamethasone was used for drug-loaded phase-transition microbubbles model to explore the potential of theranostic microbubbles.

Results: Finally, these three resulting copolymer MBs with average size of 4–5 μm exhibited well enhancement of ultrasound imaging under the influence of different frequencies and mechanical index, and they exhibited a longer contrast-enhanced ultrasound imaging time and higher resistance to mechanical index compared with SonoVue in vitro and in vivo. In vitro drug release results also showed that these copolymer MBs could encapsulate dexamethasone drugs, and the drug release could be enhanced by ultrasonic triggering. These copolymer MBs were therapeutic MBs for targeted triggering drug release.

Conclusion: Therefore, the feasibility of block, graft, and block-graft copolymers as ultrasonic contrast agents was verified, and their ultrasonic enhancement performance in vitro and in vivo was compared. The ultrasound contrast agents developed in this work have excellent development potential in comprehensive diagnosis and treatment.

Hybridized double-shell periodic mesoporous organosilica nanotheranostics for ultrasound imaging guided photothermal therapy

Hybridized periodic mesoporous organosilica (PMO) nanoparticles are expected to provide a multifunctional theranostic platform for precision medicine by combining the advantages of different organic and inorganic components. In this work, double-shell-structured PMO nanotheranostics composed of ethane- and thioether-bridged organosilica shells were synthesized. Gold colloids were generated in situ by the thioether groups on the inner shell. The obtained double-shell PMO@Au (DSPA) has uniform size, large surface areas, ordered mesochannels and photothermal conversion capability. After being encapsulated with perfluorohexacene (PFH), DSPA-PFH produced a strong ultrasound signal upon laser irradiation due to the phase transit of PFH during hyperthermia. DSPA-PFH showed enhanced photothermal therapeutic efficacy, great ultrasound contrast, and minimal toxicity both in vitro and in vivo. These results demonstrated the distribution of different organosilica could be delicately adjusted in hybridized PMO nanoparticles. Furthermore, it showed the potential of using hybridized PMO nanoparticles as a theranostic platform for biomedical applications by combining unique characteristics of different organosilica through rational design.

Enhanced HIFU Theranostics with Dual-Frequency-Ring Focused Ultrasound and Activatable Perfluoropentane-Loaded Polymer Nanoparticles

High-intensity focused ultrasound (HIFU) has been widely used in tumor ablation in clinical settings. Meanwhile, there is great potential to increase the therapeutic efficiency of temporary cavitation due to enhanced thermal effects and combined mechanical effects from nonlinear vibration and collapse of the microbubbles. In this study, dual-frequency (1.1 and 5 MHz) HIFU was used to produce acoustic droplet vaporization (ADV) microbubbles from activatable perfluoropentane-loaded polymer nanoparticles (PFP@Polymer NPs), which increased the therapeutic outcome of the HIFU and helped realize tumor theranostics with ultrasound contrast imaging. Combined with PFP@Polymer NPs, dual-frequency HIFU changed the shape of the damage lesion and reduced the acoustic intensity threshold of thermal damage significantly, from 216.86 to 62.38 W/cm². It produced a nearly 20 °C temperature increase in half the irradiation time and exhibited a higher tumor inhibition rate (84.5% ± 3.4%) at a low acoustic intensity (1.1 MHz: 23.77 W/cm²; 5 MHz: 0.35 W/cm²) in vitro than the single-frequency HIFU (60.2% ± 11.9%). Moreover, compared with the traditional PFP@BSA NDs, PFP@Polymer NPs showed higher anti-tumor efficacy (81.13% vs. 69.34%; * p < 0.05) and better contrast-enhanced ultrasound (CEUS) imaging ability (gray value of 57.53 vs. 30.67; **** p < 0.0001), probably benefitting from its uniform and stable structure. It showed potential as a highly efficient tumor theranostics approach based on dual-frequency HIFU and activatable PFP@Polymer NPs.

Ultrasound and Photoacoustic Imaging of Laser-Activated Phase-Change Perfluorocarbon Nanodroplets

Laser-activated perfluorocarbon nanodroplets (PFCnDs) are emerging phase-change contrast agents that showed promising potential in ultrasound and photoacoustic (US/PA) imaging. Unlike monophase gaseous microbubbles, PFCnDs shift their state from liquid to gas via optical activation and can provide high US/PA contrast on demand. Depending on the choice of perfluorocarbon core, the vaporization and condensation dynamics of the PFCnDs are controllable. Therefore, these configurable properties of activation and deactivation of PFCnDs are employed to enable various imaging approaches, including contrast-enhanced imaging and super-resolution imaging. In addition, synchronous application of both acoustic and optical pulses showed a promising outcome vaporizing PFCnDs with lower activation thresholds. Furthermore, due to their sub-micrometer size, PFCnDs can be used for molecular imaging of extravascular tissue. PFCnDs can also be an effective therapeutic tool. As PFCnDs can carry therapeutic drugs or other particles, they can be used for drug delivery, as well as photothermal and photodynamic therapies. Blood barrier opening for neurological applications was recently demonstrated with optically-triggered PFCnDs. This paper specifically focuses on the activation and deactivation properties of laser-activated PFCnDs and associated US/PA imaging approaches, and briefly discusses their theranostic potential and future directions.

Photoacoustic Properties of Polypyrrole Nanoparticles

Photoacoustic imaging, an emerging modality, provides supplemental information to ultrasound imaging. We investigated the properties of polypyrrole nanoparticles, which considerably enhance contrast in photoacoustic images, in relation to the synthesis procedure and to their size. We prepared polypyrrole nanoparticles by water-based redox precipitation polymerization in the presence of ammonium persulphate (ratio nPy:nOxi 1:0.5, 1:1, 1:2, 1:3, 1:5) or iron(III) chloride (nPy:nOxi 1:2.3) acting as an oxidant. To stabilize growing nanoparticles, non-ionic polyvinylpyrrolidone was used. The nanoparticles were characterized and tested as a photoacoustic contrast agent in vitro on an imaging platform combining ultrasound and photoacoustic imaging. High photoacoustic signals were obtained with lower ratios of the oxidant (nPy:nAPS ≥ 1:2), which corresponded to higher number of conjugated bonds in the polymer. The increasing portion of oxidized structures probably shifted the absorption spectra towards shorter wavelengths. A strong photoacoustic signal dependence on the nanoparticle size was revealed; the signal linearly increased with particle surface. Coated nanoparticles were also tested in vivo on a mouse model. To conclude, polypyrrole nanoparticles represent a promising contrast agent for photoacoustic imaging. Variations in the preparation result in varying photoacoustic properties related to their structure and allow to optimize the nanoparticles for in vivo imaging.