Agnieszka Ewa Wiącek

Potato starch extrudates, chemically modified by a K₂CO₃ catalyst and enriched with two types of edible oils (rapeseed or sunflower) at varying concentrations (3%, 6%, 9%), were used as film substrates. This study was carried out as a continuation of previous research on analogous extrudates in the form of dry powders and liquid solutions. The main objective was to determine surface properties of polysaccharide films as a function of oil type and concentration to monitor their wettability, biocompatibility, and functional characteristics (e.g., transparency, colour, thickness, flexibility, solubility). Advancing and receding contact angles for polar liquids (water and formamide) and non-polar diiodomethane were measured on the base and oil-modified extruded starch films. Based on these measurements, the surface free energy of the films was determined using the contact angle hysteresis (CAH) model. Optical profilometry confirmed the wettability results through surface morphology and roughness evaluation. Additionally, FTIR analysis of the films was compared to the FTIR spectra of extruded starch powders. Combining these methods provided an in-depth characterization of the films, thereby improving control over their stability and wettability, which is essential for applications in the pharmaceutical and food industries to extend product freshness and enhance resistance to oxidation and spoilage.

This study focused on elucidating the effects of chitosan (Ch), hyaluronic acid (HA), and titanium dioxide nanoparticles (nano-TiO₂) on the physicochemical characteristics of a model bacterial membrane (layer) composed of the phospholipid DPPG (1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt). The membrane was prepared on mica using the Langmuir–Blodgett (LB) technique from an aqueous subphase containing Ch, HA and/or TiO₂. Its surface properties were subsequently characterized by optical profilometry and surface free energy estimation. The nanoscale topography of the DPPG layer provided a biomimetic platform that reflects the organization of bacterial membranes, enabling a precise evaluation of how external agents, such as Ch, HA, and nano-TiO₂, modify the surface’s structural and energetic properties. The results showed that the LB films exhibit mildly heterogeneous topography, which can be attributed to lipid domains with distinct molecular packing densities. Depending on the type of biopolymer employed with TiO₂, distinct topographic architectures of the DPPG monolayers were obtained. Furthermore, the presence of nano-TiO₂ was clearly manifested as a topographic irregularity, while the analysis of hydrophilic–hydrophobic properties revealed a structurally perturbed lipid film. The results provide detailed insight into how these specific molecules (Ch, HA, nano-TiO₂) interact at the molecular level with model bacterial membranes, offering a comprehensive picture of cell–microenvironment interactions.

The field of polysaccharide systems, primarily chitosan and its derivatives, is a constantly evolving area of science. It offers significant promise for many practical applications due to the numerous beneficial properties of these biopolymers. This trend is confirmed by the next special issue of the journal “Molecules”, titled “Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—Second Edition.” This issue is devoted to the latest advances in polysaccharide research conducted in leading laboratories worldwide, with a particular emphasis on new perspectives and the latest, interesting applications in the food, agricultural, medical, biotechnological, and tissue engineering industries. The manuscripts included in this collection focus on research data regarding the production of these systems, their modification, and the application of highly specialized methods to advance science and, above all, improve health and quality of life. This special issue is organized and thematically divided into several areas related to medical and food applications, the combination of polysaccharides with other substances such as polymers, and theoretical studies. Several of the chapters conclude with a review article or even several. All articles (24 in total) included in this special issue are of high quality and represent the latest trends in research on innovative polysaccharide systems.

Starch systems and their extrudates can be used as edible films, carriers, and encapsulants for bioactive substances in various industries, primarily the food, medicine, and pharmacy industries. Using appropriate modification methods, it is possible to alter their physicochemical properties to improve specific functional parameters, thereby enhancing their application potential. The aim of this study was to characterize potato starch extrudates enriched with two types of edible oils (rapeseed or sunflower) at concentrations of 3%, 6%, and 9%. Chemical modification was carried out using K₂CO₃ as a catalyst. The structure of native and modified starch extrudates was examined using optical/confocal microscopy, FTIR, and LTNA (low-temperature nitrogen adsorption). Analogous starch dispersions were studied using static and dynamic light scattering, SLS/DLS, nephelometric methods, and electrophoretic mobility measurements to determine surface charge levels and stability. Additionally, viscosity curves were determined as a function of time and temperature. It was found that starch extrudates with 6% sunflower oil content showed optimal functional properties, characterized by greater stability, higher structural order, and better oil complexation. These findings directly translate into significant potential applications, including the development of functional products in the food industry.

Achieving a high nutritional value of food often involves fortifying microorganisms (such as bacteria and yeast) used in baking and dairy industry with essential elements. The aim of this study was to investigate the effect of a pulsed electric field (PEF) on the penetration and accumulation of Ca²⁺ and Mg²⁺ ions into model membranes of the food-grade yeast Saccharomyces cerevisiae. Simplified model membranes (monolayers and liposomes) were constructed using the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC). The Langmuir monolayer technique, dynamic light scattering (DLS) and microelectrophoresis were employed to characterize the physicochemical properties of the model membranes investigated. The results showed significant molecular-level differences in the interactions of the selected cations with lipid monolayers and bilayers in liposome structures. Both cations deeply penetrated the membrane’s hydrophilic region, yet two competing effects were evident: expansion induced by hydrated Mg²⁺ and condensation driven by Ca²⁺ bridging. Furthermore, the application of PEF increased the concentration of ions absorbed by the liposomes. Specifically, optimized PEF parameters resulted in cation accumulation within the model membranes, ranging from 6 to 13%. This finding correlates well with the increased Ca²⁺ and Mg²⁺ uptake observed in real yeast cells, providing a deeper understanding of the cell membrane-environment interface and the underlying processes.

The primary goal of this research was the multi-aspect physicochemical characterisation of a hybrid material based on chitosan, a hyaluronic acid, and TiO2 in terms of antibacterial and biocompatible properties. To harness their natural potential, chitosan and hyaluronic acid were employed, as well as titanium(IV) oxide to enhance mechanical stability. The physicochemical behaviour and stability of binary and ternary systems were investigated, along with wettability, topography and surface free energy. Biomimetic methods were used to approximate the behaviour and interactions of components within individual dispersions with representative phospholipids of model biological membranes. Understanding these parameters is essential for the proper functioning of the biomaterial within a living organism. Two different types of phospholipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine) were selected for the study of cell membranes. In contrast, the sodium salt of 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) was used as a typical bacterial model. The obtained results confirmed the possibility of potential applications of the spectrum of chitosan/hyaluronic acid-based systems in the cosmetics, medical and pharmaceutical industries.

The field of colloid systems is still a developing scientific area, but a very promising one for many practical applications

Natural polysaccharides are biocompatible and biodegradable; therefore, they can be widely used in drug delivery, tissue engineering and wound healing. In this context, the interactions between polysaccharides, drugs and biological membranes are of great interest. In this paper, a 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) monolayer was used as a model membrane to study the interactions with polysaccharides: chitosan (Ch) and/or hyaluronic acid (HA) and a nonsteroidal anti-inflammatory drug (NSAID) naproxen (NAP). The changes in the physicochemical properties of the model membrane were characterized by means of the Langmuir monolayer technique combined with Brewster angle microscopy (BAM). Compression/adsorption isotherms and morphology images were obtained at 20 °C. They allowed us to determine the effect of the subphase type (Ch, HA, Ch–HA) on the behavior of DPPC monolayers in the absence and presence of NAP, their elasticity, morphology and stability as a function of time. A potential mode of interactions between the phospholipid, polysaccharides and drug responsible for the change in membrane properties was proposed. These interactions regulate the efficiency of drug delivery systems, being of importance for living organisms in pain relief and wound healing.

The aim of this paper was to design, prepare and characterise chitosan (Ch) and cyclosporine A (CsA) mixed films deposited on a plasma-activated polyethylene terephthalate (PET) polymer surface to be used as a cover for implantable blood vessel stents. The PET polymer coated with Ch and CsA layers was immersed in simulated body fluid (SBF) to examine how the obtained layers can behave in the environment of human body fluids. Time-of-flight secondary ion mass spectrometry was employed to determine the chemical composition of the deposited films and to analyse the spatial distribution of molecules on the PET surface. The results showed the controlled release of CsA from the chitosan matrix. It can be concluded that the modification of the PET polymer with layers of chitosan and CsA has great application potential in the tissue engineering as a biocompatible stent of blood vessels with therapeutic properties.