Silica coating of polymer nanowires produced via nanoimprint lithography from femtosecond laser machined templates

Abstract

In this paper we report on the fabrication of regular arrays of silica nanoneedles by deposition of a thin layer of silica on patterned arrays of polymer nanowires (or polymer nanohair). An array of high-aspect-ratio nanoscale diameter holes of depths greater than 10 µm was produced at the surface of a fused silica wafer by an amplified femtosecond laser system operated in single-pulse mode. Cellulose acetate (CA) film was imprinted into the nanoholes and peeled off to form a patterned array of standing CA nanowires, a negative replica of the laser machined nanoholes. The cellulose acetate replica was then coated with silica in a chemical vapor deposition process using silicon tetrachloride vapor at 65 °C. Field emission scanning electron microscopy, focused ion beam sectioning, energy dispersive x-ray analysis and Fourier-transform infrared spectroscopy were used to characterize the silica nanoneedles. Precisely patterned, functionalized arrays of standing silica nanoneedles are useful for a number of applications.

Labeling of HeLa cells using ZrO 2 : Yb 3 + - Er 3 + nanoparticles with upconversion emission

“…3(b) shows a broadening of the bands centered at 3600 and 564 cm −1 due to the presence of Si─OH and Si─O─Si bonds, respectively. 61,62 Other peaks at ∼2923 and 2351 cm −1 are related to C─H bonds and CO 2 impurities, respectively. The band located in the range of 3000 to 3400 cm −1 is associated with amine groups.…”

Cell interaction study method using novel 3D silica nanoneedle gradient arrays

“…An amplified femtosecond laser system was operated in single-pulse mode to pattern fused silica substrate of 500 μm thickness in air using a 160× microscope objective lens ( NA = 1.25 in water) with 780 nm laser pulse central wavelength, 160 fs temporal length, and ~5.2 μJ energy per pulse [29–31]. The pattern made on the template was a 2×2 matrix of quadrants, where each quadrant is a 2D gradient in nanohole spacing.…”

“…CA replica-on-PDMS-on-glass coverslip was then left at room temperature for 24 hours for PDMS to crosslink for easy handling of the CA nanoneedles. The glass coverslip with CA replica was then placed on an aluminum SEM peg using a sticky tab (Lift-N-Press ™ , Structure Probe Inc., West Chester, PA) and subjected to a two-step chemical vapor deposition process at 65°C for silica deposition to form silica nanoneedles, details of which can be found in reference [29]. Briefly, CA replica was first exposed to silicon tetrachloride (SiCl 4 ) vapor for 5 minutes in a beaker and then to water vapor (H 2 O) for 5 minutes in another beaker.…”

Nitric oxide- and cisplatin-releasing silica nanoparticles for use against non-small cell lung cancer

“…S3 (a) shows the FTIR spectrum of template extracted AMS1. The sharp band at 1030 cm −1 is assigned to the Si\ \O\ \Si asymmetric stretching vibration [52]. The bands at 950 cm −1 and 780 cm − 1 are assigned to Si\ \O defect sites and the symmetric Si\ \O\ \Si stretching, respectively.…”

“…The bands at 950 cm −1 and 780 cm − 1 are assigned to Si\ \O defect sites and the symmetric Si\ \O\ \Si stretching, respectively. The band at 560 cm − 1 reflects a coupling of the Si\ \O stretching to the O\ \Si\ \O and Si\ \O\ \Si bending modes [52]. A band at 428 cm −1 is due to the combination of bending and rocking modes of Si\ \O\ \Si or O\ \Si\ \O bond [52].…”