Engineered nano–bio cellular interfaces driven by vertical nanostructured materials are set to spur transformative progress in modulating cellular processes and interrogations. In particular, the intracellular delivery—a core concept in fundamental and translational biomedical research—holds great promise for developing novel cell therapies based on gene modification. This study demonstrates the development of a mechanotransfection platform comprising vertically aligned silicon nanotube (VA‐SiNT) arrays for ex vivo gene editing. The internal hollow structure of SiNTs allows effective loading of various biomolecule cargoes; and SiNTs mediate delivery of those cargoes into GPE86 mouse embryonic fibroblasts without compromising their viability. Focused ion beam scanning electron microscopy (FIB‐SEM) and confocal microscopy results demonstrate localized membrane invaginations and accumulation of caveolin‐1 at the cell–NT interface, suggesting the presence of endocytic pits. Small‐molecule inhibition of endocytosis suggests that active endocytic process plays a role in the intracellular delivery of cargo from SiNTs. SiNT‐mediated siRNA intracellular delivery shows the capacity to reduce expression levels of F‐actin binding protein (Triobp) and alter the cellular morphology of GPE86. Finally, the successful delivery of Cas9 ribonucleoprotein (RNP) to specifically target mouse Hprt gene is achieved. This NT‐enhanced molecular delivery platform has strong potential to support gene editing technologies.
Magnetic neutral loop discharge (NLD) plasma is a new type for dry etching process characterized by effective coupling of the input electric field electron electron motion near the magnetic neutral loop (NL) region. Therefore, dense plasma can be produced and controlled spatially by changing the position of the NL. Uniformity was controlled by changing the radius of NL temporally during the etching using a repetition frequency of 0.1 Hz, so that the deviation of the SiO2 etch rate was within 2% (3σ) on 200-mm-diam wafer. In nanoscale pattern etching processes, we found that CHF2+ ions played an important role in very high aspect ratio profile etching. In CHF2+ ion-rich plasma, ZEP photoresist patterned 20 nm space was successfully etched 800 nm in depth at the pressure of about 0.3 Pa, using CH2F2, C4F8, and O2.
The electron temperature Te is one of the key parameters for process plasma because the decomposition of most reactive gases depends on the kinetic energy of electrons in the plasma. Pressure is another important parameter in the etching process for microelectromechanical systems (MEMS). Low pressure can avoid etch product substrate redepositing by reducing the collision between neutral particles and etch products in the gas phase. Also, low pressure may reduce the scattering of incident ions in the sheath that may reduce the negative taper angle for trench etching. Therefore, this study is focused on low pressure (<0.67 Pa), low Te plasma production for optical MEMS etching processes. To reduce the Te and keep the high density of the plasma, use of a parallel turn antenna was proposed and it was applied in magnetic neutral loop discharge plasma, where the Te is desirably reduced to about 2.5 eV while the density is about 1.2×1011 cm−3 at pressure of 0.2 Pa. With this improvement in plasma production, fused quartz and chemical vapor deposition SiO2 were successfully etched in a trench 5–40 μm deep at a high etch rate of over 500 nm/min. The vertical angles are about 90° and the surface roughness is less than 50 nm as evaluated by a scanning electron microscope picture, where Cr, WSi and Si were used as hard masks of SiO2 in order to achieve the selectivity required.
Low-k materials etching for FLARE™ and a porous silica were carried out in a magnetic neutral loop discharge plasma at low pressure, below 1 Pa. Fluorinated carbon molecules were used as etching gases for porous silica. The etch rate of the porous silica was approximately two times higher than that of thermal SiO2. This result means that consumption of perfluoro compound (PFC) gases is suppressed below at approximately half volumes. And organic low-k materials etching where ammonia gas or a gas mixture of nitrogen and hydrogen were used instead of PFC gas is an environmentally friendly process. After investigating an influence of a N2/H2 mixture ratio in the organic materials etch process, a good experimental condition to get a low microloading profile was found at a N2 ratio of 70%–80%. Under this condition N2+ and N2H+ ions were dominant, and the signal intensity of the N2H+ ion showed a maximum value in the mass spectrum. This may mean N2+ and N2H+ ions play an important role for a low microloading etching. The nitrogen may be adsorbed on the surface and a thin passivation film may be created on the sidewall surface.
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