Hyperthermotherapy enhances antitumor effect of 5-aminolevulinic acid-mediated sonodynamic therapy with activation of caspase-dependent apoptotic pathway in human glioma.

Sonodynamic therapy (SDT) has shown great potential as an approach for cancer treatment, and hyperthermotherapy (HT) is also a promising cancer therapy. Here, we investigate whether HT could improve the efficacy of SDT and to make a preliminary exploration on potential mechanism. Xenograft tumor was established in nude mice model, and SNB19 and U87MG glioma cell lines were utilized for in vitro experiment. Alamar blue assay was performed to assess cell viability. Optical microscope was used to characterize the morphology changes of the glioma cells induced by SDT and HT treatments. Apoptotic rate, mitochondrial membrane potential (MMP), and intracellular production of reactive oxygen species (ROS) were examined by flow cytometer. The cell apoptosis of tumor tissues were detected by TUNEL assay. Furthermore, the expression of apoptosis-related proteins was detected with Western blot in vitro and immunohistochemistry in vivo. SDT plus HT group could significantly reduce the cell viability with circular-cell morphological change, compared with SDT group, and cell viability was decreased depending on raise of 5-ALA concentration, ultrasound exposure time, and temperature. The results also indicate that HT increased a conspicuous apoptosis, ROS production, and a remarkable loss in MMP induced by 5-ALA-SDT in vitro. Meanwhile, our data also demonstrated that the combined treatment could significantly induce apoptosis and delay tumor growth in vivo. Furthermore, in both in vitro and in vivo experiments, SDT plus HT group expressed significantly higher protein levels of Bax and cleaved caspase-3, 8, and 9 compared to SDT, HT, and control groups and significantly lower protein level of bcl-2 than the other three groups, while the expression of these proteins was unchanged between HT and control groups. HT may provide an important promotion on 5-ALA-SDT and further propose that SDT in combination with HT is a new potential application for the treatment of human glioma.

Double plasmonic nanodisks design for electromagnetically induced transparency and slow light.

An analog of plasmonic system for electromagnetically induced transparency (EIT), in which a small nanodisk with a big side-coupled-nanodisk is directly coupled to the metal-insulator -metal (MIM) waveguide, has been proposed and investigated theoretically and numerically. When the resonant frequencies of the two nanodisks differ not too much, a powerful EIT-like effect can be obtained, and the transparency window can be easily tuned by adjusting the radii of the two nanodisks. The plasmonic device can be used as a high-performance EIT-like filter with transmission over 80% and full width at half-maximum (FWHM) less than 30nm, besides, the novel structure shows a high group index over 355. The system paves a new way toward highly integrated optical circuits and networks, especially for wavelength-selective, ultrafast switching, light storage and nonlinear devices.

Asymmetric band-pass plasmonic nanodisk filter with mode inhibition and spectrally splitting capabilities.

A compact wavelength band-pass filter based on metal-insulator-metal (MIM) nanodisk cavity is proposed and numerically investigated by using Finite-Difference Time-Domain (FDTD) simulations. It is found that the transmission characteristics of the filter can be easily adjusted by changing the geometrical parameters of the radius of the nanodisk and coupling distance between the nanodisk and waveguide. By extending the length of input/output waveguides, the filter shows the resonant mode inhibition function. Basing on this characteristic, a two-port wavelength demultiplexer is designed, which can separate resonant modes inside the nanodisk with high transmission up to 70%. The waveguide filter may become a potential application for the design of devices in highly integrated optical circuits.