Using a chitosan nanolayer as an efficient pH buffer to protect pH-sensitive supramolecular assemblies

Abstract

It is attractive to control the properties of macro objects and films by employing simple nanolayer composites, as in the case of nanoarchitectured Layer-by-Layer (LbL) coating. In this paper, we use chitosan as a surface-based pH buffer to protect adsorbed supramolecular fibres from pH-mediated disassembly. Protons are generated on a titania surface under illumination at 405 nm leading to an appreciable pH change on the surface. We find that supramolecular polymers that are highly sensitive to pH change will not disassemble after irradiation if a nanolayer of chitosan is present. We propose that chitosan can be used as an efficient pH-responsive protective layer for pH sensitive soft materials.

Photocatalytic Regulation of an Autocatalytic Wave of Spatially Propagating Enzymatic Reactions

“…On the contrary, having the same photoactivity center (TiO 2 ), it doesn't happen for the system of TiO 2 /PSS/PEI. It should also be noted that the presence of a proton on TiO 2 was shown by us before as well as efficient pH‐buffering of 2 nm chitosan layer …”

“…In our recent work, we studied, in detail, the process of local pH changes by irradiation of a TiO 2 surface, suggesting titania as a robust surface for light controlled proton pumping . We used the phenomena of light‐pH coupling on titania for a non‐destructive modulation of pH‐sensitive layers, adsorption/ desorption of proteins, control of preosteoblast migration, bacteria assembly, self‐healing of hydrogel, and even a regulation of a “prebiotic nucleotides” assembly . In this context, we got interested in using pH gradients on titania for regulating biomolecular reaction networks.…”

“…[3] We used the phenomena of light-pH couplingo nt itania for an on-destructive modulation of pH-sensitive layers, [4] adsorption/d esorptiono fp roteins, [5] control of preosteoblast migration, [6] bacteria assembly, [7] self-healing of hydrogel, [8] and even ar egulation of a" prebiotic nucleotides"a ssembly. [9] In this context, we got interested in using pH gradients on titania for regulating biomolecular reactionnetworks. The coupling of pH oscillators to pH-dependent complexation equilibriap roposes an especiallya ttractive way to construct new oscillatory reactions.…”

“…It should also be noted that the presence of ap roton on TiO 2 was shownb y us before [3] as wella se fficient pH-buffering of 2nmc hitosan layer. [9] Finally,w ec haracterized enzymatic reaction-diffusion network coupled to the TiO 2 based system in ah ydrogel [20] media ( Figure 5). Autocatalytic formation of Tr from Tg can sustain autocatalytic reactionfront.…”

Thin and Flexible Ion Sensors Based on Polyelectrolyte Multilayers Assembled onto the Carbon Adhesive Tape

“…19,22 We suppose that polyelectrolyte multilayers formed by layer-by-layer assembly 23,24 have hydration activity 25−28 and can serve as the inner electrode solution in potentiometric sensors. 29−31 This paper describes the design and fabrication of a flexible ion-sensing electrochemical adhesive tape (AT)-based analytical device for potentiometric measurements of potassium and sodium ions. This sensing platform has a carbon AT that contains ISEs with conventional ion-selective membranes (ISMs) immobilized within a polyelectrolyte multilayer as the pseudo-inner solution and ion-to-electron transducer.…”