In situ probing of cell-cell communications with surface- enhanced Raman scattering （SERS） nanoprobes and microfluidic networks for screening of immunotherapeutic drugs

Discovering novel drugs for cancer immunotherapy requires a robust in vitro drug screening platform that allows for straightforward probing of cell-ceil communications. Here, we combined surface-enhanced Raman scattering （SERS） nanoprobes with microfluidic networks to monitor in situ the cancer-immune system intercellular communications. The microfluidic platform links up immune cells with cancer cells, where the cancer-cell secretions act as signaling mediators. First, gold@silver core--shell nanorods were employed to fabricate SERS immunoprobes for analysis of the signaling molecules. Multiple cancer secretions in a tumor microenvironment were quantitatively analyzed by a SERS-assisted three-dimensional （3D） barcode immunoassay with high sensitivity （1 ng/mL）. Second, in an on-chip cell proliferation assay, multiple immunosuppressive proteins secreted by cancer cells were found to inhibit activation of immune cells, indicating that the platform simulates the physiological process of cancer-immune system communications. Furthermore, potential drug candidates were tested on this platform. A quantitative SERS immunoassay was performed to evaluate drug efficacy at regulating the secretion behavior of cancer cells and the activity of immune cells. This assay showed the suitability of this platform for in vitro drug screening. It is expected that the fully integrated and highly automated SERS-microfluidic platform will become a powerful analytical tool for probing intercellular communications and should accelerate the discovery and clinical validation of novel druKs.

Numerical study of radio wave propagation in clear air acoustic scatterer

This paper numerically investigates the radio wave scattering by the artificial acoustic disturbance in the atmospheric boundary layer. The numerical model is based on the finitedifference time-domain（FDTD） method for radio wave propagation and fluid simulation for atmospheric disturbance by acoustics waves. The characteristics of radio wave scattering propagation in the artificial acoustic perturbations are investigated by this numerical model. The numerical simulation results demonstrate that the radio wave propagation scattered by acoustic scatterer has the characteristic of forward tropospheric scatter. When the radio waves are scattered, they distribute in all directions; a majority of radio waves continues to propagate along the original direction, and only a small part of the energy is scattered. For the same acoustic scatterer, if we merely change the radio wave emission elevation, the horizontal spans of forward scattering radio wave packets centers gradually decrease with the increasing of emission elevations; and the energy of wave packets increases firstly and then decreases with launching elevation, reaching the maximum at a certain angle. If we merely change the wave emitting position, the horizontal spans decrease with the increasing of emission positions, and the energy of wave packets also increases firstly and then decreases with launch position, reaching the maximum at a certain position. This approach can be very promising for atmospheric scatter communications.