Katerina Lebedeva

Thermosensitive biopolymer gelatin–alginate hydrogels are promising for use as dressings for wound healing and drug delivery. This work presents fluorescence arising from the internal fluorophores of alginate and gelatin biopolymers in thermosensitive hydrogels modified with calcium- and sodium-containing humic acids before and after their impregnation with the hemostatic drug aminocaproic acid. A new approach of using fluorescence emission spectra, along with the analysis of morphological features, optical properties, and the elemental composition of dried hydrogels, is used as a tool for monitoring the ability of these hydrogels for the thermosensitive delivery of a hemostatic drug. A comparative analysis made it possible to select the optimal composition of hydrogels suitable for the targeted delivery of aminocaproic acid through a gel–sol transition at physiological temperatures. Optimal concentrations of sodium-containing humic acids in gelatin–alginate hydrogels of 2.5 wt.% and 5 wt.% provided a gel–sol transition temperature of about 37 °C. The quantum yield of fluorescence of 8–10% upon introduction of 20 wt.% aminocaproic acid into these hydrogels indicates that this hemostatic drug does not destroy three-dimensional networks formed by molecules of gelatin, alginate, and humic acids, the gel–sol transition temperature for which is maintained at a physiological level without significant contracture of the wound dressing.

In the infrastructure of the future, based on intelligent computerized systems and control and monitoring devices, the smart home is part of the Internet of Things (IoT). However, in addition to the need to address energy consumption, the widespread adoption of smart homes may also exacerbate the growing problem of increasing amounts of non-recyclable e-waste from IoT devices. Compared to synthetic plastics, biopolymers offer many unique advantages such as robust structure, light weight, mechanical flexibility, biocompatibility, biodegradability and renewability. Biopolymers, which are abundant in natural products such as cellulose, silk fibroin, polylactic acid, chitosan, collagen, keratin, alginate, starch and gelatin, have great promise for the production of environmentally friendly Internet of Things devices. They are ideal candidates for the use of low-temperature sol–gel coating and ink-printing processes to facilitate the development of low-cost, large-area flexible electronic devices. This work presents developments known from the literature, as well as the results of original research on the use of biopolymer materials to create flexible, wearable and textile electronic devices, such as sensors, energy storage devices and nanogenerators, soft hydrogel actuators and wireless communication devices that are promising for the Internet of Things but have not yet been implemented in smart homes. Graphical Abstract

In this article, effective 3D printing modeling technology of smart bio-medical polymeric hydrogel transdermal materials based on gelatin and sodium alginate, modified by humic acids, was researched. Such smart biologically active polymeric hydrogel materials showed interesting applicability in tissue engineering fields due to their intrinsic biological compatibility, adaptability, and capacity to replicate the extracellular matrix environment. A literature review was carried out and proved that 3D printing modeling technology is a perspective for the functional effect on the smart bio-medical polymer hydrogel transdermal properties. Smart biomedical polymeric transdermal hydrogel patches were produced using a micromolding technique. A stereolithography (SLA) 3D printer was used to print the master mold. The three-stage technology of lignite humic acids modification of smart biologically active polymeric hydrogel transdermal microneedles patches based on gelatin, hydroxypropyl methylcellulose, and sodium alginate was designed. It was shown that modification of gelatin-sodium alginate and hydroxypropyl methylcellulose-sodium alginate biopolymer hydrogels by humic acids makes it possible to obtain smart biologically active polymeric hydrogel transdermal materials with an increased swelling degree and ability to improve the skin moisture-lipid balance (from the initial moisture 34–36 % and fatness 8–10, they increase to 58–66 % and 52–60 %). Finally, the developed 3D printing modeling technology of smart bio-medical polymeric hydrogel transdermal materials hydrogel based on gelatin sodium alginate, modified by humic acids, is a transdermal material with required properties.

The possibility of increasing the complexity of the operational properties of environmentally safe biodegradable polymer hydrogel materials based on hydroxypropyl methylcellulose due to modification by humic acids from lignite is considered. As a result of this research, environmentally safe hybrid hydrogel films with antibacterial properties were received. In the framework of physicochemical studies, it was determined by IR spectroscopy that hydroxypropyl methylcellulose modified with humic acids hybridmaterials are received by the mechanism of matrix synthesis, which is accompanied by hydroxypropyl methylcellulose crosslinking through multipoint interaction with the carboxyl group of humic acids. Regularities in terms of changes in water absorption, gelation time, and mold emergence time regarding the environmentally safe biodegradable polymer hydrogel materials based on hydroxypropyl methylcellulose depending on the humic acid content were revealed. It was established that the optimal humic acid content in environmentally safe biodegradable hydrogel films with bactericidal properties based on hydroxypropyl methylcellulose is 15% by mass. It was also established that the hybrid modification of hydroxypropyl methylcellulose with humic acids allows them to preserve their biodegradation properties while giving them antibacterial properties. The environmentally safe biodegradable hydrogel films with bactericidal properties based on hydroxypropyl methylcellulose and humic acids are superior in their operational characteristics to known similar biodegradable hydrogel films based on natural biopolymers.