Photocatalytic Regulation of an Autocatalytic Wave of Spatially Propagating Enzymatic Reactions

Nanoparticles in Polyelectrolyte Multilayer Layer-by-Layer (LbL) Films and Capsules—Key Enabling Components of Hybrid Coatings

Originally regarded as auxiliary additives, nanoparticles have become important constituents of polyelectrolyte multilayers. They represent the key components to enhance mechanical properties, enable activation by laser light or ultrasound, construct anisotropic and multicompartment structures, and facilitate the development of novel sensors and movable particles. Here, we discuss an increasingly important role of inorganic nanoparticles in the layer-by-layer assembly—effectively leading to the construction of the so-called hybrid coatings. The principles of assembly are discussed together with the properties of nanoparticles and layer-by-layer polymeric assembly essential in building hybrid coatings. Applications and emerging trends in development of such novel materials are also identified.

Storage of Information Using Periodic Precipitation

In the present work, transparent flexible thin polymer films with silver patterns have been created. The resulting structures made by the printing method represent a new alternative approach for recording, protecting, and transmitting information as well as for nonlinear gradient material formation. An alphabet for process automatization was created, and an automated system for recording and reading information was developed. To protect the information, we suggest the usage of a classic XOR function: the idea of scrambling is to demonstrate the simple and clear example of coding the ITMO University logo, and the code is provided. Additionally, the resulting samples are functional gradient materials with peaks of surface plasmon resonance. In the following, automated peak decoding by UV-vis spectroscopy allows an additional physicochemical method for structure decoding.

Coupling pH-Regulated Multilayers with Inorganic Surfaces for Bionic Devices and Infochemistry

This article summarizes more than 10 years of cooperation with Prof. Helmuth Möhwald. Here we describe how the research moved from light-regulated feedback sustainable systems and control biodevices to the current focus on infochemistry in aqueous solution. An important advanced characteristic of such materials and devices is the pH concentration gradient in aqueous solution. A major part of the article focuses on the use of localized illumination for proton generation as a reliable, minimal-reagent-consuming, stable light-promoted proton pump. The in situ scanning vibration electrode technique (SVET) and scanning ion-selective electrode technique (SIET) are efficient for the spatiotemporal evolution of ions on the surface. pH-sensitive polyelectrolyte (PEs) multilayers with different PE architectures are composed with a feedback loop for bionic devices. We show here that pH-regulated PE multilayers can change their properties-film thickness and stiffness, permeability, hydrophilicity, and/or fluorescence-in response to light or electrochemical or biological processes instead of classical acid/base titration.

Towards sustainable diagnostics: replacing unstable H2O2 by photoactive TiO2 in testing systems for visible and tangible diagnostics for use by blind people

Blind and color blind people cannot use colorimetric diagnostics; the problem is especially severe in rural areas where high temperatures and the absence of electricity challenge modern diagnostics. Here we propose to replace the unstable component of a diagnostic test, H2O2, with stable TiO2. Under UV irradiation, TiO2 forms reactive oxygen species that initiate polymerization of acrylamide causing liquid-to-gel transition in an analyte-dependent manner. We demonstrate that specific DNA sequences can be detected using this approach. This development may enable the detection of biological molecules by users with limited resources, for example in developing countries or for travelers in remote areas.

Nanostructured Layer-by-Layer Polyelectrolyte Containers to Switch Biofilm Fluorescence

The development of stimuli-responsive nanocontainers is an issue of utmost importance for many applications such as targeted drug delivery, regulation of the cell and tissue behavior, making bacteria have useful functions and here converting light. The present work shows a new contribution to the design of polyelectrolyte (PE) containers based on surface modified mesoporous titania particles with deposited Ag nanoparticles to achieve chemical light upconversion via biofilms. The PE shell allows slowing down the kinetics of a release of loaded l-arabinose and switching the bacteria luminescence in a certain time. The hybrid TiO₂/Ag/PE containers activated at 980 nm (IR) illumination demonstrate 10 times faster release of l-arabinose as opposed to non-activated containers. Fast IR-released l-arabinose switch bacteria fluorescence which we monitor at 510 nm. The approach described herein can be used in many applications where the target and delayed switching and light upconversion are required.