Logo: to the web site of Uppsala University

Natural polymer-based hydrogels hold significant potential for sustainable agriculture by enhancing soil hydration and enabling the controlled release of nutrients. This study shows an easy synthetic approach to substitute up to 75% of commonly used polyacrylamide (PAAm) for commercial agro hydrogels by kraft lignin, keeping swelling performance on the same level. A new semisynthetic hydrogel has been synthesized via cross-linking of kraft lignin produced via the LignoBoost process (LB) with PAAm. The ratio of LB and PAAm in the hydrogel composition and cross-linking density were optimized to obtain hydrogels with suitable performance properties. Hydrogel samples were characterized by thermogravimetric analysis, differential scanning calorimetry, and Fourier transform infrared (FTIR) spectroscopy to evaluate the main characteristics and suggest possible reaction mechanisms and by scanning electron microscopy to study features of the hydrogel network. The investigation of functional properties demonstrated that optimized hydrogel samples with 60% lignin in the composition possess water swelling capacity up to 235 g g^–1 and can significantly increase the water retention of the soil when 2.5% hydrogel is added to the substrate. Moreover, obtained lignin-derived hydrogels have the ability to retain and slow-release urea fertilizer. Thus, lignin-derived urea formulations ensure the sustained cumulative release of urea within 8 days under laboratory conditions, while unencapsulated urea possesses a cumulative release of 97% within 1 h. Investigation of biodegradation using a soil burial test showed that weight loss ranges from 9.5% to 14.5% after 40 days for different hydrogel samples. The proposed method of synthesis of lignin-based hydrogels opens new frontiers in advancing sustainable agricultural technologies.

The study presents a streamlined one-step process for producing highly porous, metal-free, N-doped activated carbon (N-AC) for CO2 capture and herbicide removal from simulated industrially polluted and real environmental systems. N-AC was prepared from kraft lignin─a carbon-rich and abundant byproduct of the pulp industry, using nitric acid as the activator and urea as the N-dopant. The reported carbonization process under a nitrogen atmosphere renders a product with a high yield of 30% even at high temperatures up to 800 °C. N-AC exhibited a substantial high N content (4–5%), the presence of aliphatic and phenolic OH groups, and a notable absence of carboxylic groups, as confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Boehm’s titration. Porosity analysis indicated that micropores constituted the majority of the pore structure, with 86% of pores having diameters less than 0.6 nm. According to BET adsorption analysis, the developed porous structure of N-AC boasted a substantial specific surface area of 1000 m2 g–1. N-AC proved to be a promising adsorbent for air and water purification. Specifically, N-AC exhibited a strong affinity for CO2, with an adsorption capacity of 1.4 mmol g–1 at 0.15 bar and 20 °C, and it demonstrated the highest selectivity over N2 from the simulated flue gas system (27.3 mmol g–1 for 15:85 v/v CO2/N2 at 20 °C) among all previously reported nitrogen-doped AC materials from kraft lignin. Moreover, N-AC displayed excellent reusability and efficient CO2 release, maintaining an adsorption capacity of 3.1 mmol g–1 (at 1 bar and 25 °C) over 10 consecutive adsorption–desorption cycles, confirming N-AC as a useful material for CO2 storage and utilization. The unique cationic nature of N-AC enhanced the adsorption of herbicides in neutral and weakly basic environments, which is relevant for real waters. It exhibited an impressive adsorption capacity for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at 96 ± 6 mg g–1 under pH 6 and 25 °C according to the Langmuir–Freundlich model. Notably, N-AC preserves its high adsorption capacity toward 2,4-D from simulated groundwater and runoff from tomato greenhouse, while performance in real samples from Fyris river in Uppsala, Sweden, causes a decrease of only 4–5%. Owing to the one-step process, high yield, annual abundance of kraft lignin, and use of environmentally friendly activating agents, N-AC has substantial potential for large-scale industrial applications.

In the present work, N-substituted glutamic acid, polyethylene and polypropylene glycols have been used to design biocompatible copolyesters via Steglich reactions. Due to the presence of alternating hydrophilic and hydrophobic blocks in their structures, these copolyesters are able to form self-stabilized nanoparticle dispersions in aqueous media. The lipophilic core of these nanoparticles can solubilize poorly water-soluble compounds and release them into a model of lipids in a human body. Moreover, the obtained copolyesters possess no cytotoxic effects over a wide concentration range. Thus, we conclude that obtained copolyesters show significant promise for further development as drug delivery systems.

The work presents the results of research on the formation of a hydrogel polymer matrix during the gelatin crosslinking with a dioxirane derivative of poly(ethylene glycol) and experiments on studying their properties. The crosslinking process of type A gelatin using poly(ethylene glycol) diglycidyl ether (PEGDE 500) was optimized by changing the gelatin: PEGDE ratio without using any other factors. The properties of the obtained hydrogels were studied, in particular the gel fraction amount, the degree of swelling in different media, mechanical properties, pore size, cytotoxicity, the ability to absorb and release antiseptic drugs, and bactericidal properties of hydrogel samples filled with an antiseptic agent (chlorhexidine). The crosslinking reaction has been found to be the most efficient at gelatin: PEGDE 500 ratio ranging from 1:3 to 1:5. In this case, the formation of highly elastic hydrogels with maximum fraction amount and high mechanical properties was observed (the samples were not destroyed under compression). Moreover, only within this ratio range, the obtained hydrogels retained their shape when heated to 40 °C. The pore sizes of the swollen hydrogel clearly depend on the crosslinker content. The high values of the degree of swelling in the exudate-simulating fluid in combination with mechanical strength allow the development of wound dressings based on hydrogels of the developed composition. Crosslinking of gelatin with PEGDE 500 allows to obtain gelatin-based hydrogels in a controlled manner which does not require subsequent purification steps. The resulting material does not exhibit cytotoxicity during in vitro studies on living cells. The hydrogel filled with an antiseptic drug is capable of releasing it by 50% within the first day into the medium of saline and exudate-simulating fluid. The antimicrobial properties of the hydrogel containing chlorhexidine are confirmed by the effective inhibition of the growth of Escherichia coli and Staphylococcus aureus bacteria.

Polyester pseudo-poly(amino acid)s due to their biodegradability and biocompatibility are promising materials for the development of dispersed systems for drug delivery. It is essential for drug delivery systems to reach the target site within a certain period before they are eliminated or degraded. Biodegradable materials should meet the following criteria: (1) possess surface-active properties; (2) be non-toxic; (3) form self-stabilized dispersions with the size of the dispersed phase in the range of 10–100 nm. Polyesters based on N-derivatives of dicarboxylic α-amino acids and hydrophilic PEG diols modified with phosphate group meet the requirements to the dispersed drug delivery systems. Obtained polyesters have a complex architecture consisting of hydrophilic fragments, which stabilize the system, and lipophilic fragments, which solubilize biologically active substances. The phosphate group introduced into the hydrophilic chain of polyoxyethylene glycol provides chemisorption of a number of biologically active substances due to the formation of ionic bonds between them. Synthesized polyesters form self-stabilized dispersed systems, which do not require additional stabilizing agents when used for medical applications.

Prolonged use of antibiotics can cause toxicity in human and animal cells and lead to the development of antibiotic resistance. The development of drug delivery systems for enhanced antibacterial properties of antibiotics could reduce toxic effects and minimize the development of resistance. The aim of this study was to evaluate the effectiveness of oxytetracycline in complexes with new polyphosphate ester-type transporters and to investigate the antimicrobial effect of these complexes on Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus growth in vitro. Two polyphosphate ester-type transporters with different molecular weights were synthesized, and oxytetracycline was attached through the phosphorus groups. To determine the sensitivities of microorganisms, oxytetracycline hydrochloride and oxytetracycline complexes with polyphosphate ester-type transporters (P4 and P6) were added to liquid and solid media with E. coli, P. aeruginosa, and S. aureus in different doses. Oxytetracycline in complex with polyphosphate ester-type transporters at low doses (2.3 to 3.8 μg/disk or μg/mL) in both solid and liquid media inhibits the growth of S. aureus more effectively than oxytetracycline alone. The maximum influence on E. coli growth on solid media is observed at a dose of 8 μg/disk of oxytetracycline in combination with both P4 and P6 polyphosphate ester-type transporters. P. aeruginosa growth under the influence of oxytetracycline in combination with polyphosphate-ester type transporters in a liquid medium depends on the dose of antibiotic and the day of cultivation.