Igor Zhitomirsky

This investigation addressed challenges in the delivery of poorly soluble drugs, and the colloidal processing of polymer–ceramic composites by fabrication of advanced supramolecular hydrogels. Polygalacturonic acid (PGA) polymer and 18β-glycyrrhetinic acid (GA) drug, both characterized by poor aqueous solubility, were selected as model building blocks for supramolecular hydrogels. Meglumine (MG) served as a multifunctional component in the gels, acting as a building block as well as an alkalizing and solubilizing agent for PGA and GA. Investigations revealed gel formation mechanisms, which were based on the electrostatic interactions of deprotonated anionic carboxylic groups of PGA and GA with protonated amino groups of MG and the hydrogen bonding of PGA polymer and GA molecules. The feasibility of the fabrication of PGA-MG and GA-MG gels opened an avenue for the fabrication of PGA-GA-MG gels. The composite gels provided a platform for drug delivery, and the kinetics of drug release from the composite gels containing MG excipient were investigated. Composite gels were obtained from colloidal dispersions, containing bioceramics, such as hydroxyapatite, silica, and titania, and bioglass in the PGA solutions in the presence of MG. The results of this investigation pave the way for the fabrication of novel supramolecular and composite gels loaded with various functional materials.

Cobalt–copper bimetallic oxides (CoCuO_x) show great potential for constructing high-performance micro-supercapacitors (MSCs) for micro-electronic applications. However, their poor conductivity and complex preparation procedures significantly hinder their broad applications. To address these challenges, oxygen-vacancy-modified CoCuO_x-based binder-free electrodes were fabricated using a one-step computer numerical control wire electrical discharge machining (CNCWEDM) strategy. This approach enabled the fabrication of CoCuO_x-based maze-like MSCs (CoCuMMSCs) with designable electrochemical performance, which could be simply controlled by their geometric shape and machining voltage. Subsequently, theoretical simulations were conducted for studying the effect of MSCs geometric shape on their capacitive behavior. Remarkably, the CoCuMMSCs fabricated by a machining voltage of 100 V achieved the maximum capacitance of 32.8 mF cm⁻² at 0.15 mA cm⁻². Furthermore, the CoCuMMSCs demonstrated outstanding performance at ultrahigh scan rates of up to 50,000 mV s⁻¹, exceeding by more than two orders of magnitude the values previously reported in the literature. The obtained results proved that the development of the CNCWEDM technique facilitated manufacturing CoCuMMSCs devices with excellent performance by the comprehensive utilization of oxygen-vacancy incorporation, synergistic effect of cobalt and copper oxides, binder-free electrode design, proper device construction and controllable machining voltage. The advanced CNCWEDM strategy creates a new pathway for the high-efficiency fabrication of high-performance bimetallic-oxide-based micro-electronic devices, such as MSCs, intelligent micro-sensors and micro-batteries.

The incorporation of redox-active molecules into aqueous electrolytes addressed the challenges in the development of energy storage devices by enhancing energy density, expanding voltage windows, and improving cycling stability. Aqueous zinc-ion hybrid capacitors (ZICs), which combine the characteristics of metal-ion batteries and supercapacitors, have emerged to meet high energy-power demands. Herein, we investigate the irreversible and reversible dynamics of azobenzene compounds in the development of redox electrolytes for ZIC applications. The results reveal that Sunset Yellow (SY) additives promote reversible Zn²⁺ stripping/plating at the Zn anode through ion–ligand coordination, while the redox behavior of the –NN– group enhances the interfacial charge transfer. The passivation behavior of redox electrolytes, derived by SY molecules, was investigated using in situ electrochemical atomic force microscopy. Morphology evolution, coupled with nanomechanical tests, shed light on the transformation of SY-containing electrolytes. The redox electrolytes improve the lifespan of Zn//Zn cells from 50 to 1700 cycles at 2 mA cm⁻² and 1 mA h cm⁻² by suppressing parasitic reactions and mitigating by-product formation. The redox-enhanced ZIC delivers an increased capacity of 113.3 mA h g⁻¹ with improved cycling stability, compared to 75.2 mA h g⁻¹ of ZnSO₄ electrolytes without SY molecules at 0.6 mA g⁻¹. A range of azobenzene-based compounds with varying structures were investigated to demonstrate the synergistic modulating effects. The results demonstrate the molecular engineering of redox electrolytes and provide fundamental insights into electrochemical interphase transformation.