Cellular Deformations Induced by Conical Silicon Nanowire Arrays Facilitate Gene Delivery

Engineered cell–nanostructured interfaces generated by vertically aligned silicon nanowire (SiNW) arrays have become a promising platform for orchestrating cell behavior, function, and fate. However, the underlying mechanism in SiNW-mediated intracellular access and delivery is still poorly understood. This study demonstrates the development of a gene delivery platform based on conical SiNW arrays for mechanical cell transfection, assisted by centrifugal force, for both adherent and nonadherent cells in vitro. Cells form focal adhesions on SiNWs within 6 h, and maintain high viability and motility. Such a functional and dynamic cell–SiNW interface features conformational changes in the plasma membrane and in some cases the nucleus, promoting both direct penetration and endocytosis; this synergistically facilitates SiNW-mediated delivery of nucleic acids into immortalized cell lines, and into difficult-to-transfect primary immune T cells without pre-activation. Moreover, transfected cells retrieved from SiNWs retain the capacity to proliferate—crucial to future biomedical applications. The results indicate that SiNW-mediated intracellular delivery holds great promise for developing increasingly sophisticated investigative and therapeutic tools. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Light-induced reflectivity transients in black-Si nanoneedles

© 2015 Elsevier B.V. All rights reserved. The change in reflectivity of black-Si (b-Si) upon optical excitation was measured by the pump-probe technique using picosecond laser pulses at 532 (pump) and 1064 nm (probe) wavelengths. The specular reflection from the random pattern of plasma-etched b-Si nano-needles was dominated by the photo-excited free-carrier contribution to the reflectivity. The kinetics of the reflectivity were found to be consistent with surface structural and chemical analysis, performed by scanning and transmission electron microscopy, and spectroscopic ellipsometry. The surface recombination velocity on the b-Si needles was estimated to be ~102cm/s. Metalization of b-Si led to much faster recombination and alteration of reflectivity. The reflectivity spectra of random b-Si surfaces with different needle lengths was modeled by a multi-step refractive index profile in the Drude formalism. The dip in the reflectivity spectra and the sign reversal in the differential reflectivity signal at certain b-Si needle sizes is explained by the model

Geometrical management of optical vortices by closed-path metallic nanoslits

We propose and experimentally demonstrate a geometrical approach to the controlled generation of optical phase singularities at small scale by using metallic nanostructures, thereby offering a novel strategy towards singular nanophotonics

Tailoring plasmonic field enhancement in spatial and spectral domains

Three-dimensional patterning of gold nano-particles on SiO2 and Si substrates is performed by ion-beam lithography with 15-20 nm resolution. Realization of an on-demand achiral and chiral modifications of nano-structures are demonstrated. Simulations of optical properties of the obtained nano-architectures reveal the possibility to tailor the field enhancement both in the spatial and spectral domains, which are foreseen to be applicable for light harvesting and opto-mechanics at nanoscale

Preventive medicine : an international journal devoted to practice and theory

Three-dimensional patterning of gold nano-particles on SiO2 and Si substrates is performed by ion-beam lithography with 15-20 nm resolution. Realization of an on-demand achiral and chiral modifications of nano-structures are demonstrated. Simulations of optical properties of the obtained nano-architectures reveal the possibility to tailor the field enhancement both in the spatial and spectral domains, which are foreseen to be applicable for light harvesting and opto-mechanics at nanoscale

Optoplasmonics: hybridization in 3D

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THz photomixer with a 40nm-wide nanoelectrode gap on low-temperature grown GaAs

Abstract not reproduced here by request of the publisher. The text is available from: http://dx.doi.org/10.1117/12.203374

Nanoscale precision in ion milling for optical and terahertz antennas

Plasmonics and nanoscale antennas have been intensively investigated for sensors, metasurfaces and optical trapping where light control at the nanoscale enables new functionalities. To confine and manipulate the light in tiny spaces sub-wavelength antennas should be used with dimensions from micro- to nano-meters and are still challenging to make. Direct fabrication/modification of nanostructures using focused ion beam (FIB) milling is demonstrated for several types of antennas. Arrays of identical nanoparticles were fabricated in a single step by (i) milling gold films or (ii) by modifying structures which were already defined by electron beam or mask projection lithography. Direct FIB writing enables to exclude resist processing steps, thus making fabrication faster and simpler. Sensor areas of 25x25 μm2 of densely packed nanoparticles separated by tens-of-nanometers were fabricated in half an hour (103 μm2/h throughput at 90 nm resolution). Patterns of chiral nanoparticles by groove inscription is demonstrated. The processing speed and capability to mill complex 3D surfaces due to depth of focus not compromised over micrometers length, makes it possible to reach sub-50 nm resolution of direct write. FIB technology is practical for emerging applications in nano-fabrication/photonic/fluidic/magnetic applications