Poly-N-Isopropyl-acrylamide/Acrylic Acid Copolymers for the Generation of Nanostructures on Mica Surfaces and as Hydrophobic Host Systems for the Porin MspA from Mycobacterium smegmatis

Abstract

The work presented here aims at utilizing poly-N-isopropyl-acrylamide/acrylic acid copolymers to create nanostructured layers on mica surfaces by a simple spin-casting procedure. The average composition of the copolymers determined by elemental analysis correlates excellently with the feed composition indicating that the radical polymerization process is statistical. The resulting surfaces were characterized by Atomic Force Microscopy (magnetic AC-mode) at the copolymer/air interface. Postpolymerization modification of the acrylic acid functions with perfluoro-octyl-iodide decreased the tendency towards spontaneous formation of nanopores. Crosslinking of individual polymer chains permitted the generation of ultraflat layers, which hosted the mycobacterial channel protein MspA, without compromising its channel function. The comparison of copolymers of very similar chemical composition that have been prepared by living radical polymerization and classic radical polymerization indicated that differences in polydispersity played only a minor role when poly-N-isopropyl-acrylamide/acrylic acid copolymers were spincast, but a major role when copolymers featuring the strongly hydrophobic perfluoro-octyl-labels were used. The mean pore diameters were 23.8±4.4 nm for P[(NIPAM)95.5-co-(AA)4.5] (PDI (polydispersity index)=1.55) and 21.8±4.2 nm for P[(NIPAM)95.3-co-(AA)4.7] (PDI=1.25). The depth of the nanopores was approx. 4 nm. When depositing P[(NIPAM)95-co-(AA)2.8-AAC8F17 2.2] (PDI=1.29) on Mica, the resulting mean pore diameter was 35.8±7.1 nm, with a depth of only 2 nm.

Integrating Ionic Gate and Rectifier Within One Solid‐State Nanopore via Modification with Dual‐Responsive Copolymer Brushes

“…The molar ratios for the AAc to NIPAAm in the polymerization process were 0:100 (homo‐NIPAAm), 5:95 (nominal 5% AAc content), 20:80 (nominal 20% AAc content), and 100:0 (homo‐AAc). Bossmann et al have reported that the actual fraction of AAc unit in the copolymer chain on a mica surface, using similar radical polymerization method, correlates well with the initial feed composition 79. However, the composition of the copolymer chains produced in bulk solution may be different from the copolymer brushes synthesized in a confined and charged environment in a nanopore via a grafting‐from approach.…”

A New Heterogeneous Photocathode Based on Ruthenium(II)quaterpyridinium Complexes at TiO2 Particles

“…HCl) to roughen the surface and then thoroughly washed in H 2 O (three times) and MeOH. The glass slide was dried at 365 K for at least 12 h. Silver-epoxy glue (silver conductive epoxy, MG Chemicals #8331) was deposited onto one side of the roughened glass plate by a spin-casting procedure (described in detail in ref ), the glass slide was subjected to 1000 rpm for 300 s. The glass slide was then brought in contact with RuC2COOH@TiO 2 or Ru3PHOS@TiO 2 on a filter paper at 300 K. After 24 h, the surplus material was tapped off, and the composite electrode was thoroughly washed with MeOH (two times) and then with water (three times), dried at 365 K, and then stored under argon at room temperature.…”

Controllable Switching of Enzyme Activity by Poly(N‐isopropylacrylamide)‐Based Microgels Through Mineralization of Calcium Carbonate in High Pressure CO2

“…The ability to reversibly regulate and control enzymatic reaction with external stimuli provides new opportunities for the development of bioprocesses [1][2][3][4], chemical separations [5,6], biohybrid materials [7][8][9][10], bioelectronics [11,12], and biosensor technologies [13][14][15]. Thermo-responsive polymers are widely studied and important classes of stimuli-responsive polymers.…”