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Studies have determined that ultrasound-activated microbubbles can increase the membrane permeability of tumor cells by triggering membrane perforation (sonoporation) to improve drug loading. However, because of the distinct cavitation events adjacent to each cell, the degree of drug loading appeared to be heterogeneous. The relationship between the long-term fate trend and the degree of drug loading remains unclear. To investigate the time-lapse viability of diversity loading cells, fluorescein isothiocyanate-dextran (FITC-dextrans) was used as a molecular model mixed with 2% v/v SonoVue microbubbles (Bracco, Milan, Italy) and exposed to various peak negative pressures (0.25 MPa, 0.6 MPa, 1.2 MPa), 1 MHz frequency and 300 μs pulse duration. To select a suitable parameter, the cavitation activity was measured, and the cell analysis was performed by flow cytometry under these acoustic pressures. The sonoporated cells were then categorized into 3 sub-groups by flow cytometry according to the various fluorescence intensity distributions to analyze their long-term fate. We observed that the stable cavitation occurred at 0.25 MPa and microbubbles underwent ultra-harmonic emission, and obvious broadband signals were observed at 0.6 MPa and 1.2 MPa, suggesting the occurs of inertial cavitation. The cell analysis further showed the maximum delivery efficiency and cell viability at 0.6 MPa, and it was selected for the following experiment. The categorization displayed that the fluorescence intensity of FITC-dextrans in sub-groups 2 and 3 were approximate 5.62-fold and 19.53-fold higher than that in sub-group 1, respectively. After separation of these sub-groups, the apoptosis and necrosis ratios in all 3 sub-groups of sonoporated cells gradually increased with increasing culture time and displayed no significant difference in either the apoptosis (p > 0.05) or necrosis (p > 0.05) ratio after 6 h and 24 h of culture, respectively. Further analysis using Western blot verified that the long-term fate of sonoporated cells involves the mitochondrial signaling proteins. These results provide better insight into the role of cavitation-enhanced permeability and a critical guide for acoustic cavitation designs.

The distribution of metals in cyanobloom-forming lakes, and potential risks of these metals during irrigation with water derived from the bloom were evaluated in this study. Seven metals were monitored throughout a cyanobacterial bloom season in Lake Taihu. Cyanobloom bio-dilution of the targeted metals could be explained by the negative relationships between total phytoplankton metal contents (Cu, Fe, Zn, Pb and Cr) and Chl a concentrations (p0.05). Meanwhile, the ratios of extracellular bound to total cellular bound metals (Cu, Zn, Pb, Cr and Cd) were positively correlated with the ratios of cyanophyta to total phytoplankton (p0.01), indicating the enhanced extracellular bound of these metals during cyanobloom period. Secondly, Cd, Pb and Cr were detected in several local vegetables. In comparison to reference vegetables, vegetables (e.g., radish, soybean, and cowpea), which were irrigated with cyanobloom broth collected from Lake Taihu, presented high health risk index (HRI) and were not safe for human consumption. Collectively, the frequent dominant colonial Microcystis blooms which performed high metal affinity might mediate the distribution of heavy metals in lake and potentially transferred these pollutants into terrestrial system.

Gas-assisted therapy and diagnosis of tumors have attracted extensive interest due to their low toxicity and convenience, but are severely limited by the uncontrollable gas release. In this work, we proposed a kind of ammonia borane (AB) and doxorubicin (DOX) co-loaded and PEGylated Hollow Mesoporous Polydopamine (AB/DOX@HMPDA-PEG) nanoparticles for acid-sensitive hydrogen (H2)-assisted ultrasonic (US) imaging and chemotherapy of drug-resistant tumors. The in vitro experiment showed that as a high H2-storage molecule, AB can controllably release massive H2 in an acidic environment. For one thing, the H2 release in the acidic tumor environment and lysosomes of tumor cells in vivo helped to improve the US imaging performance; for another, it facilitated the lysosomal escape of nanoparticles, DOX release from nanoparticles, and blockage of mitochondrial respiratory chain. Furtherly, the blockage of mitochondrial respiratory chain reduced the production of triphosadenine (ATP), thereby decreasing the expression of heat shock protein 90 (HSP90) and promoting the therapeutic effect of DOX on drug-resistant tumors. Therefore, the nanoparticles provided an effective platform for controllable H2-assisted chemotherapy and US imaging of the drug-resistant tumors.

SonoVue microbubbles could serve as artificial nuclei for ultrasound-triggered stable and inertial cavitation, resulting in beneficial biological effects for future therapeutic applications. To optimize and control the use of the cavitation of SonoVue bubbles in therapy while ensuring safety, it is important to comprehensively understand the relationship between the acoustic parameters and the cavitation behavior of the SonoVue bubbles. An agarose-gel tissue phantom was fabricated to hold the SonoVue bubble suspension. 1-MHz transmitting transducer calibrated by a hydrophone was used to trigger the cavitation of SonoVue bubbles under different ultrasonic parameters (i.e., peak rarefactional pressure (PRP), pulse repetition frequency (PRF), and pulse duration (PD)). Another 7.5-MHz focused transducer was employed to passively receive acoustic signals from the exposed bubbles. The ultraharmonics and broadband intensities in the acoustic emission spectra were measured to quantify the extent of stable and inertial cavitation of SonoVue bubbles, respectively. We found that the onset of both stable and inertial cavitation exhibited a strong dependence on the PRP and PD and a relatively weak dependence on the PRF. Approximate 0.25MPa PRP with more than 20μs PD was considered to be necessary for ultraharmonics emission of SonoVue bubbles, and obvious broadband signals started to appear when the PRP exceeded 0.40MPa. Moreover, the doses of stable and inertial cavitation varied with the PRP. The stable cavitation dose initially increased with increasing PRP, and then decreased rapidly after 0.5MPa. By contrast, the inertial cavitation dose continuously increased with increasing PRP. Finally, the doses of both stable and inertial cavitation were positively correlated with PRF and PD. These results could provide instructive information for optimizing future therapeutic applications of SonoVue bubbles.

International audience; Design of simple-component theranostic agents with enhanced tumor accumulation represents a novel strategy in the area of precision nanomedicine for effective tumor theranostics. Herein, we report an innovative theranostic strategy based on ultrasound-enhanced tumor accumulation of a theranostic agent of phosphorus dendrimer-copper(II) complexes (1G3-Cu). The employed 1G3-Cu complexes represent a drug-free nanotheranostic agent with a simple composition possessing an r1 relaxivity of 0.7024 mM−1 s−1 for T1-weighted magnetic resonance (MR) imaging and an IC50 of 1.24 μM to inhibit the growth of a pancreatic cancer cell line. We show that cancer cells can be inhibited by the 1G3-Cu complexes through the activation of the apoptotic process with the upregulation of Bax, P53 and PTEN, downregulation of Bcl-2, and decrease of intracellular ATP. With the assistance of ultrasound targeted microbubble destruction (UTMD) technology that can increase cell membrane permeability temporarily via sonoporation effect, the 1G3-Cu complexes enable enhanced tumor MR imaging and chemotherapy due to their improved tumor accumulation. With the proven minimal toxicity to normal tissues at imaging and therapeutic doses, the prepared 1G3-Cu complexes may be potentially employed for UTMD-enhanced theranostics of different types of cancer.