In this study, we developed a novel and rapid method to generate in vitro three-dimensional (3D) multicellular tumor spheroids using a surface acoustic wave (SAW) device. A SAW device with single-phase unidirectional transducer electrodes (SPUTD) on lithium niobate substrate was fabricated using standing UV photolithography and wet-etching techniques. To generate spheroids, the SAW device was loaded with medium containing human breast carcinoma (BT474) cells, an oscillating electrical signal at resonant frequency was supplied to the SPUDT to generate acoustic radiation in the medium. Spheroids with uniform size and shape can be obtained using this method in less than 1 minute, and the size of the spheroids can be controlled through adjusting the seeding density. The resulting spheroids were used for further cultivation and were monitored using an optical microscope in real time. The viability and actin organization of the spheroids were assessed using live/dead viability staining and actin cytoskeleton staining, respectively. Compared to spheroids generated using the liquid overlay method, the SAW generated spheroids exhibited higher circularity and higher viability. The F-actin filaments of spheroids appear to aggregate compared to that of untreated cells, indicating that mature spheroids can be obtained using this method. This spheroid generating method can be useful for a variety of biological studies and clinical applications.
Ring of close packed gold nanoparticle arrays offers many fascinating properties that are not found in others assembly
patterns. One of the most fantastic features of this unique organization is its ability to reroute shorter wavelengths of
light in the visible region of electromagnetic spectrum, making it a very promising nanophotonic components for guiding
light at the true nanoscale. Also, the creation of ring with gold nanoparticles can be used to make the world's smallest
biosensors possible for multiple disease detection. Herein, we demonstrate a new paradigm for generating rings of
CTAB-capped gold nanorods with the implementation of surface acoustic wave (SAW) atomization. With the ultrafast
microfluidics actuation, the SAW atomizer can rapidly generate submicron fluids and efficiently form ring arrays onto
desired substrates in less than 1s via the evaporative self-assembly process. The technique is able to provide a rational
control over the of microfluids size distributions to engineer the smaller monodisperse rings arrays at micrometer scale.
This microfluidics-assisted evaporative self assembly approach is also applicable to DNA-capped gold nanoparticles.
The non-uniform mass distribution of ring is formed upon the pinning of contact line to substrates during a far-fromequilibrium
dewetting process. Our method opens an avenue towards the ring assembly of gold nanoparticles in their
ultimate microscopic minimal threshold to facilitate the generation of metamaterials.
Pulmonary drug delivery transports the drug formulations directly to the respiratory tract in the form of inhaled
particles or droplets. Because of the direct target treatment, it has significant advantages in the treatment of
respiratory diseases, for example asthma. However, it is difficult to produce monodispersed particles/droplets in
the 1-10 micron range, which is necessary for deposition in the targeted lung area or lower respiratory airways,
in a controllable fashion. We demonstrate the use of surface acoustic waves (SAWs) as an efficient method for
the generation of monodispersed micron dimension aerosols for the treatment of asthma. SAWs are ten nanometer
order amplitude electroacoustic waves generated by applying an oscillating electric field to an interdigital
transducer patterned on a piezoelectric substrate. The acoustic energy in the waves induces atomization of the
working fluid, which contains a model drug, albuterol. Laser diffraction techniques employed to characterize the
aerosols revealed mean diameter of the aerosol was around 3-4 μm. Parallel experiments employing a one-stage
(glass) twin impinger as a lung model demonstrated a nearly 80% of atomized drug aerosol was deposited in
the lung. The aerosol size distribution is relatively independent of the SAW frequency, which is consistent with
our predictive scaling theory which accounts for the dominant balance between viscous and capillary stresses.
Moreover, only 1-3 W powers consumption of SAW atomization suggests that the SAW atomizer can be miniaturized
into dimensions commensurate with portable consumer devices.