Gabriela Biliuta

This review presents a focused assessment of the rapidly expanding field of gelatin-based eutectogels and identifies the gaps in current literature that justify this examination. Research on deep eutectic solvents (DESs and NADES) has advanced quickly, yet there is still no integrated view of how these solvent systems influence adhesion in gelatin-based gels. Eutectogels are soft materials formed by gelling DESs or NADES with biopolymers. Gelatin is widely used because it is biocompatible, biodegradable, and readily available. We provide a clear overview of the chemistry of DESs and NADES and describe how gelatin forms networks in these media. The review summarizes established knowledge on adhesion, highlighting the contributions of polymer network density, interfacial hydrogen bonding, and solvent mobility. New perspectives are introduced on how these factors interact to control adhesion strength, toughness, and reversibility. A key topic is the role of hydrogen bond donors (HBDs) and acceptors (HBAs). They define the hydrogen bonding environment of the solvent and represent an underexplored way to tune mechanical and adhesive behavior. Examples such as moisture-resistant adhesion and temperature-responsive bonding show why these systems offer unique and adjustable properties. The review concludes by outlining major challenges, including the lack of standardized adhesion tests and constraints in scalable production, and identifying directions for future work.

Topical approaches to dermatophytosis have the advantage of targeted therapy and minimal side effects and are patient-friendly. The present study focused on obtaining thin, flexible, and transparent bioadhesive polymeric films loaded with terbinafine hydrochloride (TH), in order to be administered to the skin affected by fungal infection. Polymeric films based on pullulan (P), oxidized pullulan (T-OP), sodium carboxymethylcellulose (NaCMC), and glycerin were obtained by the casting and evaporation technique, and the solubility of the drug was significantly increased by micellar solubilization with Tween-80, thus avoiding the use of organic solvents. Physico-chemical characterization through the FTIR technique and EDX analysis indicates the absence of strong interactions between the drug and the polymer, and the loading efficiency highlights the uniform distribution of the drug. The mechanical properties, bioadhesion, contact angle, and water sorption capacity highlight optimal adhesion parameters on the skin. In vitro studies indicate a prolonged drug release, in the first 300 min, of 80% and 60% for F2_TH and F1_TH, respectively, and the release kinetics follow the Weibull model. Significant antifungal activity was obtained for both polymeric films. The biocompatibility of the ingredients, the gentle technique for obtaining the films, and the results obtained from their analysis represent promise for their applicability in topical antifungal treatment.

Metal ions, which are naturally occurring in food, soil, and water, are present in every part of the environment. Therefore, it is imperative to identify those using accessible and economical methods. In this study, a novel two‐step chemical modification process for pullulan, a natural polymer, is presented. This process yields a macromolecular derivative with considerably increased fluorescence, enabling efficient detection of specific metal ions. Furthermore, the recently synthesized polymer displays distinctly divergent characteristics in comparison with the native pullulan, a consequence of the undergone chemical reactions. These include the existence of fluorescence and solubility in organic solvents, which are lacking from the initial polymer. Subsequent to exhaustive thermal and spectral analysis, the synthesized polymer's capacity to discern disparate metal ions is investigated. The interaction between metal ions and the pullulan derivative is monitored to ascertain the extent of fluorescence quenching during this process. The synthesized polymer exhibits the greatest sensitivity to Fe³⁺ and Cu²⁺ among the various cations that are examined, while Pb²⁺ and the other ions demonstrate satisfactory results. The paper also discusses the underlying quenching mechanism and possible future applications.

Along with the increased usage of cellulose in the manufacture of novel materials, those of its derivatives that have good solubility in water or organic solvents have become increasingly important. In this study, hydroxypropyl cellulose (HPC), a cellulosic derivative with distinct features, was utilized to investigate how two of the most-selective oxidation methods currently available in the literature act on the constituent OH groups of both the side chain and the anhydroglycosidic unit in HPC. The oxidation reactions were carried out first using TEMPO, sodium hypochlorite, and sodium bromide, then sodium periodate (NaIO₄), for 5 h. A combination of these two protocols was applied. The amount of aldehyde and number of carboxylic groups introduced after oxidation was determined, while the changes in the morphological features of oxidized HPC were, additionally, assessed. Furthermore, utilizing Fourier-transform infrared spectra, X-ray diffraction, and thermogravimetric studies, the chemical structure, crystallinity, and thermal stability of the oxidized HPC samples were examined and compared.

The excellent biological properties of chitosan (CS) together with the increased oxygen permeability of polyvinyl alcohol (PVA) were the prerequisites for the creation of a wound healing dressing that would also function as a system for L-arginine (L-arg) and caffeine (Caff) delivery. Using the freezing/thawing method, 12 hydrogels were obtained in PVA:CS polymer ratios of 90:10, 75:25, and 60:40, and all were loaded with L-arg, Caff, and the mixture of L-arg and Caff, respectively. Afterwards, an inorganic material (zeolite–Z) was added to the best polymeric ratio (75:25) and loaded with active substances. The interactions between the constituents of the hydrogels were analyzed by FTIR spectroscopy, the uniformity of the network was highlighted by the SEM technique, and the dynamic water vapor sorption capacity was evaluated. In the presence of the inorganic material, the release profile of the active substances is delayed, and in vitro permeation kinetics proves that the equilibrium state is not reached even after four hours. The synergy of the constituents in the polymer network recommends that they be used in medical applications, such as wound healing dressings.

The aim of this study was to synthesize silver nanoparticles (AgNPs) using cellulose derivatives and to evaluate their antimicrobial potential. As effective reducing and stabilizing agents for AgNPs, cellulose derivatives, such as hydroxypropyl cellulose (HPC), methylcellulose (MC), ethylcellulose (EC), and cellulose acetate (CA), were used. Their ability to reduce silver ions as well as the size of the resulting AgNPs were compared. The formation and stability of the reduced AgNPs in the solution were monitored using UV-Vis analysis. The size, morphology, and charge of the AgNPs were evaluated. We found that, when using cellulosic derivatives, AgNPs with sizes ranging from 17 to 89 nm and different stabilities were obtained. The parameters, such as size and ζ potential indicate the stability of AgNPs, with AgNPs-CA and AgNPs-HPC being considered more stable than AgNPs-EC and AgNPs-MC since they show higher ζ potential values. In addition, the AgNPs showed antimicrobial activity against all reference strains and clinical isolates. MIC values between 0.0312 and 0.125 mM had a bactericidal effect on both Gram-positive and Gram-negative bacteria. The fungicidal effect was obtained at a MIC value of 0.125 mM. These results may provide rational support in the design of medical gauze products, including gauze pads, rolls, and sponges.

The C-6 in the maltotriose unit of pullulan was oxidized in an alkaline medium (pH = 10), utilizing a green method that included hydrogen peroxide (H₂O₂) as an oxidant and N-hydroxyphthalimide (NHPI) as a catalyst for various reaction times. The structure of the resulting oxidized pullulans (PO) was carefully characterized by titration, intrinsic viscosity, FTIR, ¹³C-NMR, and zeta potential. The content of carboxyl groups in PO was dependent on reaction time and varied accordingly. Furthermore, a fast reaction rate was found in the first 2–3 h of the reaction, followed by a decreased rate in the subsequent hours. FTIR and ¹³C-NMR proved that the selective oxidation of the primary alcohol groups of pullulan was achieved. The oxidation also caused the glycoside linkages in the pullulan chain to break, and the viscosity of the pullulan itself went down.