Patterning of Substrates Using Surface Relief Structures on an Azobenzene‐Functionalized Polymer Film

Abstract

remaining DTT solution was removed and the wafer was rinsed with fresh 10 % EtOH/H 2 O (3 5 mL) then EtOH (5 5 mL) then dried under a nitrogen stream followed by vacuum.GMBS Attachment: The sulfhydryl functionalized porous silicon wafer was immersed in a solution of GMBS (2.0 mg, 7.1 10 ±3 mmol) in DMF (2 mL) under nitrogen. The wafer was left to react for 3 h with occasional agitation. The remaining GMBS solution was removed and the silicon wafer was rinsed with DMF (3 5 mL) followed by EtOH (3 5 mL) then dried under a nitrogen stream followed by vacuum.b-Glucuronidase Attachment: b-Glucuronidase was obtained as a solution in 50 % glycerol/PBS from F. Hoffmann-La Roche Ltd., with an activity of approximately 200 U mL ±1 at 37 C. This solution was diluted to 100 U mL ±1 with PBS and added to the sample in a vial at room temperature. After 4 h the sample was removed and rinsed with PBS (20 mL) followed by 1 M NaCl (20 mL) and then rinsed again with PBS (20 mL).PBS Preparation: PBS buffer solution at pH 7.4 contained 50 mM Na 2 HPO 4 , 17 mM NaH 2 PO 4 , and 68 mM NaCl.Scanning Electron Microscopy: The porous silicon samples were characterized by field emission scanning electron microscopy (FE-SEM) with a Hitachi S-4500 microscope. Samples were mounted on the sample holder using carbon tape and graphite paint. SEM images were recorded with an acceleration voltage of 3 KV.Enzyme Activity Assay: The functionalized porous silicon samples were mounted in a Teflon flow cell fitted with a quartz window and connected to a UV-vis quartz cell in a closed loop. A total volume of 4 mL was re-circulated through the flow cell and the UV-vis cell with a peristaltic pump at a flow rate of 8 mL min ±1 . The rinses were performed with PBS buffer at pH 7.4 and the activity assays were performed with various concentrations of the substrate p-nitrophenylb-D-glucuronide in PBS buffer. The b-glucuronidase activity was detected as an increase of p-nitrophenol concentration measured in situ and in real time in the UV-vis cell with a Cary 300 spectrophotometer (Varian Inc.) by using the kinetics recording mode at 405 nm.Protein Assay: The BCA based protein assay (Pierce Biotechnology Inc.) was used to detect the presence of enzymes in the PBS rinse solutions used between various substrate concentrations. The MA (sodium carbonate, sodium bicarbonate and sodium tartrate in 0.2 N NaOH), MB (4 % BCA in water), and MC (4 % cupric sulfate pentahydrate in water) reagents from the kit were mixed in a 50:48:2 (v/v/v) proportion, 1 mL of working reagent was added to 1 mL of sample, and the sample±reagent mixture was incubated at 60 C for 1 h. The absorption of the solution at 562 nm was then measured with the spectrophotometer and compared to a standard (Bovin Albumin Fraction V in 0.9 % NaCl solution containing sodium azide).Photoluminescence Spectra Measurements: The photoluminescence of the functionalized porous silicon samples was also measured in situ and in real time through the quartz window of the flow cell with a Cary Eclipse fluorescence s...

Azopolymer‐based micro‐ and nanopatterning for photonic applications

“…For an azopolymer SRG to function as an etch mask, the polymer must be removed from the grating grooves to reveal the substrate. This can be achieved by partially etching the azopolymer using, for example, reactive ion etching (RIE) in oxygen plasma . Since the SRGs typically have a nearly sinusoidal surface profile, the etching time can be used as a parameter for tuning the open area of the substrate, and hence the dimensions and to some extent the geometry of the mask – note the similarity with the last example in the preceding subsection (Fig.…”

“…Depending on the material to be etched, one can use either wet or dry etching. An example of applying wet etching (in a dilute hydrochloric acid with a zinc powder catalyst) to pattern indium tin oxide (ITO) is shown in Figure . AFM images of the original SRG, the mask obtained by pre‐etching the azopolymer in oxygen plasma, and the resulting patterned ITO layer are shown in Figures (a–c), respectively.…”

Ultrastrong Anchoring on the Periodic Atomic Grooves of Black Phosphorus

“…Among these methods, surface anchoring is of particular interest because surface‐induced alignment of soft materials over large areas is highly feasible. Typically, it has been accomplished via rubbing of polymer films, photoalignment, ion‐beam irradiation, self‐assembly of monolayers, preparation of 2D material surfaces, and patterned of grooved surfaces via lithography …”

Patterning Flexible Substrates Using Surface Relief Structures in Azobenzene Functionalized Polymer Films

“…Schematic outline of the procedure used to pattern PET layer: a) a PET sheet was spin-coated with an azobenzene polymer film; b) surface relief gratings were inscribed on the polymer film using two coherent interfering laser beams; c) the sample was etched in a plasma-etcher with oxygen until all the azobenzene polymer disappeared and then rinsed with 1,4-dioxane. 940 Yang et al layer on a glass substrate using surface-relief structures formed on azobenzene functionalized polymer film (21). The present study extends this technique to patterning flexible substrates and demonstrates the creation of intricate structures on Polyethylene terephthalate (PET).…”