Bactericidal Chitosan Derivatives and Their Superabsorbent Blends with ĸ-Carrageenan.

The aim of this work is research dedicated to the search for new bactericidal systems for use in cosmetic formulations, dermocosmetics, or the production of wound dressings. Over the last two decades, chitosan, due to its special biological activity, has become a highly indispensable biopolymer with very wide application possibilities. Reports in the literature on the antibacterial effects of chitosan are very diverse, but our research has shown that they can be successfully improved through chemical modification. Therefore, in this study, results on the synthesis of new chitosan-based Schiff bases, dCsSB-SFD and dCsSB-PCA, are obtained using two aldehydes: sodium 4-formylbenzene-1,3-disulfonate (SFD) and 2-pyridine carboxaldehyde (PCA), respectively. Chitosan derivatives synthesized in this way demonstrate stronger antimicrobial activity. Carrying out the procedure of grafting chitosan with a caproyl chain allowed obtaining compatible blends of chitosan derivatives with κ-carrageenan, which are stable hydrogels with a high swelling coefficient. Furthermore, the covalently bounded poly(ε-caprolactone) (PCL) chain improved the solubility of obtained polymers in organic solvents. In this respect, the Schiff base-containing polymers obtained in this study, with special hydrogel and antimicrobial properties, are very promising materials for potential use as a controlled-release formulation of both hydrophilic and hydrophobic drugs in cosmetic products for skin health.

Bactericidal Biodegradable Linear Polyamidoamines Obtained with the Use of Endogenous Polyamines.

The work presents the synthesis of a series of linear polyamidoamines by polycondensation of sebacoyl dichloride with endogenous polyamines: putrescine, spermidine, spermine, and norspermidine-a biogenic polyamine not found in the human body. During the synthesis carried out via interfacial reaction, hydrophilic, semi-crystalline polymers with an average viscosity molecular weight of approximately 20,000 g/mol and a melting point of approx. 130 °C were obtained. The structure and composition of the synthesized polymers were confirmed based on NMR and FTIR studies. The cytotoxicity tests performed on human fibroblasts and keratinocytes showed that the polymers obtained with spermine and norspermidine were strongly cytotoxic, but only in high concentrations. All the other examined polymers did not show cytotoxicity even at concentrations of 2000 µg/mL. Simultaneously, the antibacterial activity of the obtained polyamides was confirmed. These polymers are particularly active against E. Coli, and virtually all the polymers obtained demonstrated a strong inhibitory effect on the growth of cells of this strain. Antimicrobial activity of the tested polymer was found against strains like Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. The broadest spectrum of bactericidal action was demonstrated by polyamidoamines obtained from spermine, which contains two amino groups in the repeating unit of the chain. The obtained polymers can be used as a material for forming drug carriers and other biologically active compounds in the form of micro- and nanoparticles, especially as a component of bactericidal creams and ointments used in dermatology or cosmetology.

Degradation of Polylactic Acid/Polypropylene Carbonate Films in Soil and Phosphate Buffer and Their Potential Usefulness in Agriculture and Agrochemistry.

Blends of poly(lactic acid) (PLA) with poly(propylene carbonate) (PPC) are currently in the phase of intensive study due to their promising properties and environmentally friendly features. Intensive study and further commercialization of PPC-based polymers or their blends, as usual, will soon face the problem of their waste occurring in the environment, including soil. For this reason, it is worth comprehensively studying the degradation rate of these polymers over a long period of time in soil and, for comparison, in phosphate buffer to understand the difference in this process and evaluate the potential application of such materials toward agrochemical and agricultural purposes. The degradation rate of the samples was generally accompanied by weight loss and a decrease in molecular weight, which was facilitated by the presence of PPC. The incubation of the samples in the aqueous media yielded greater surface erosions compared to the degradation in soil, which was attributed to the leaching of the low molecular degradation species out of the foils. The phytotoxicity study confirmed the no toxic impact of the PPC on tested plants, indicating it as a "green" material, which is crucial information for further, more comprehensive study of this polymer toward any type of sustainable application.

Biodegradable Polymers and Polymer Composites with Antibacterial Properties.

Antibiotic resistance is one of the greatest threats to global health and food security today. It becomes increasingly difficult to treat infectious disorders because antibiotics, even the newest ones, are becoming less and less effective. One of the ways taken in the Global Plan of Action announced at the World Health Assembly in May 2015 is to ensure the prevention and treatment of infectious diseases. In order to do so, attempts are made to develop new antimicrobial therapeutics, including biomaterials with antibacterial activity, such as polycationic polymers, polypeptides, and polymeric systems, to provide non-antibiotic therapeutic agents, such as selected biologically active nanoparticles and chemical compounds. Another key issue is preventing food from contamination by developing antibacterial packaging materials, particularly based on degradable polymers and biocomposites. This review, in a cross-sectional way, describes the most significant research activities conducted in recent years in the field of the development of polymeric materials and polymer composites with antibacterial properties. We particularly focus on natural polymers, i.e., polysaccharides and polypeptides, which present a mechanism for combating many highly pathogenic microorganisms. We also attempt to use this knowledge to obtain synthetic polymers with similar antibacterial activity.

Synthesis of Polyacids by Copolymerization of l-Lactide with MTC-COOH Using Zn[(acac)(L)H2O] Complex as an Initiator.

This work presents the results of research on the preparation of bioresorbable functional polyestercarbonates containing side carboxyl groups. These copolymers were synthesized in two ways: the classic two-step process involving the copolymerization of l-lactide and a cyclic carbonate containing a blocked side carboxylate group in the form of a benzyl ester (MTC-Bz) and its subsequent deprotection, and a new way involving the one-step copolymerization of l-lactide with this same carbonate, but containing an unprotected carboxyl group (MTC-COOH). Both reactions were carried out under identical conditions in the melt, using a specially selected zinc chelate complex, with Zn[(acac)(L)H2O] (where: L-N-(pyridin-4-ylmethylene) phenylalaninate ligand) as an initiator. The differences in the kinetics of both reactions and their courses were pictured. The reactivity of the MTC-COOH monomer without a blocking group in the studied co-polymerization was much higher, even slightly higher than l-lactide, which allowed the practically complete conversion of the comonomers in a much shorter time. The basic final properties of the obtained copolymers and the microstructures of their chains were determined. The single-step synthesis of biodegradable polyacids was much simpler. Contrary to the conventional method, this made it possible to obtain copolymers containing all carbonate units with carboxyl groups, without even traces of the heavy metals used in the deprotection of the carboxyl groups, the presence of which is known to be very difficult to completely remove from the copolymers obtained in the two-step process.

PLAGA-PEG-PLAGA Terpolymer-Based Carriers of Herbicides for Potential Application in Environment-Friendly, Controlled Release Systems of Agrochemicals.

The present study aimed to develop and prepare new polymer/herbicide formulations for their potential application in environment-friendly, controlled release systems of agrochemicals. Selected biodegradable polymers, including L-Lactide/Glycolide/PEG/Terpolymer (PLAGA-PEG-PLAGA) as well as oligosaccharide-based polymers and their blend with terpolymer, were used to prepare microspheres loaded with two soil-applied herbicides. The degradation process of the obtained polymeric microspheres was evaluated based on (1) their weight loss and surface erosion and (2) the release rate of loaded metazachlor and pendimethalin. The herbicidal effectiveness of the herbicides released to the soil from microspheres was evaluated using the European Weed Research Council (EWRC) rating scale. Moreover, the ecotoxicological effect of herbicide-loaded microspheres buried in soil on the marine bacterial species A. fischeri was assessed. It was found that the gradual degradation rate of microparticles led to the prolonged release of both herbicides that lasted for a few months, i.e., for the entire crop season, which is crucial in terms of agrochemical and environmental protection. Maltodextrin- and dextrin-based microspheres showed higher susceptibility to degradation than terpolymer-based microspheres. The microencapsulation of herbicides protected them from decomposition and excessive leaching into soil and maintained their activity for a longer period than that for non-immobilized herbicides. The ecotoxicological assessment on A. fischeri demonstrated that the proposed microsphere-encapsulated herbicides were less toxic than non-immobilized herbicides.

Biodegradable Blends of Grafted Dextrin with PLGA-block-PEG Copolymer as a Carrier for Controlled Release of Herbicides into Soil.

The presented work aimed to test influence of poly(L-lactide-co-glycolide)-block-poly (ethylene oxide) copolymer modification by blending with grafted dextrin or maltodextrin on the course of degradation in soil and the usefulness of such material as a matrix in the controlled release of herbicides. The modification should be to obtain homogenous blends with better susceptibility to enzymatic degradation. Among all tested blends, which were proposed as a carrier for potential use in the controlled release of plant protection agents, PLGA-block-PEG copolymer blended with grafted dextrin yielded very promising results for their future applications, and what is very importantly proposed formulations provide herbicides in unchanged form into soil within few months of release. The modification PLAGA/PEG copolymer by blending with modificated dextrins affects the improvement of the release profile. The weekly release rates for both selected herbicides (metazachlor and pendimethalin) were constant for a period of 12 weeks. Enzymatic degradation of modified dextrin combined with leaching of the degradation products into medium caused significant erosion of the polymer matrix, thereby leading to acceleration of water diffusion into the polymer matrix and allowing for easier leaching of herbicides outside the matrix.

Ecotoxicological impact of selected polyethylenimines toward their potential application as nitrogen fertilizers with prolonged activity.

Poly(2-oxazoline) polymers have found extensive application in the preparation of microcapsules for biomedical purposes. However, there is a scarcity of information related to their ecotoxicological assessment. Therefore, in this study, we focused on the ecotoxicity of selected polyethylenimines (PEIs) including poly(2-ethyl-2-oxazoline) (PEtOx) as an N-acyl-substituted PEI, linear polyethylenimine (LPEI) and branched polyethylenimine (BPEI). Oat (a monocotyledon) (Avena sativa) and radish (a dicotyledon) (Raphanus sativus) were selected as the representative plants, which are recommended by the Organization for Economic Cooperation and Development (OECD) 208 as the standard to test for plant growth. Shoot and root length, fresh and dry matter, level of total nitrogen in green parts of the plants, as well as total chlorophyll and carotenoids were determined. Phytotoxicity of all the tested parameters was dependent on the concentration of the examined polymers in the soil as well as on the time of their incubation in the soil. According to our results, the amount of nitrogen in green parts of the plants was increased compared to the control plants, which revealed the uptake of the plant-available form of nitrogen released from the tested PEIs. This was especially true for the plants treated with LPEI. Ecotoxicological impact of the incubated polymers in the soil against marine bacteria Allivibrio fischeri proved that, the all tested polyethylenimines may be classified as not harmful to aquatic microorganisms.

Novel (5-nitrofurfuryl)-substituted esters of phosphonoglycine - Their synthesis and phyto- and ecotoxicological properties.

Since aminophosphonate-based herbicides like glyphosate are currently one of the most popular and widely applied active agent in agrochemistry, there is an urgent need for searching new compounds among this family with potential herbicidal activity, but exhibiting low toxicity against surrounding environment. Six new (5-nitrofurfuryl)-derived aminophosphonates were synthesized for the first time and apart from the only one example of N-benzylamino(5-nitrofuryl)-methylphosphonic acid, it was the first time in the history, when this class of compounds was prepared. Their prospective and real biological properties have been followed up by evaluation of their preliminary ecotoxicology. They have been then investigated in aspect of their phytotoxicity against oat (A. sativa) and common radish (R. sativus) exhibiting moderate-to-severe toxicity for these plants. The significant selectivity towards radish (up to 3 times greater toxicity against radish) was observed in some cases. Title compounds were also tested in terms of their toxicity for freshwater crustaceans H. incongruens (ostracods) and marine luminescent bacteria A. fischeri. Although their harmful action on ostracods was not too much elevated, they were found to be highly toxic for bacteria. Various aspects of their ecotoxicity are discussed in this paper.

Evaluation of ecotoxicological impact of new pyrrole-derived aminophosphonates using selected bioassay battery.

Six new dimethyl N-arylamino(2-pyrrolyl)methylphosphonates 2a-f were synthesized by the modified aza-Pudovik reaction. Their ecotoxicological impact using battery of bioassay was assessed using Microtox and Ostracodtoxit tests as well as phytotoxicity towards two plants, dicotyledonous radish (Raphanus sativus) and monocotyledonous oat (Avena sativa) following the OECD 208 Guideline. Ecotoxicological properties of compounds 2a-f in aspect of acute and chronic toxicity were evaluated using Heterocypris incongruens and Aliivibrio fisheri tests. The obtained results showed that tested aminophosphonates 2a-f have moderate-to-high phyto- and ecotoxicological impact. They are toxic for both plants but more toxic against dicotyledonous. The investigated compounds showed important ecotoxicity against Heterocypris incongruens crustaceans and Aliivibrio fisheri bacteria. It was found that the substituents of the phenyl ring plays a key role in the degree of toxicity. Results showed that investigated compounds are ecologically toxic and that any of their application should be implemented with care.

Synthesis, Spectral Characterization of Several Novel Pyrene-Derived Aminophosphonates and Their Ecotoxicological Evaluation Using Heterocypris incongruens and Vibrio fisheri Tests.

Four diphenyl pyrene-derived aminophosphonates were synthesized. Attempts were made to synthesize diphenyl N-(R)-α-methylbenzylamino(pyren-1-yl)methylphosphonate (3e) in order to obtain the chiral aminophosphonate bearing a pyrene moiety. Because these attempts failed, dimethyl and dibenzyl N-(R)-α-methylbenzyl substituted aminophosphonates 4 and 5 were synthesized and the predominant diastereoisomer of dimethyl aminophosphonate 4 was isolated. The resolution of the diastereomeric mixture of 5 failed. Aminophosphonates 3a-d and the predominant diastereoisomer of 4 were investigated in terms of their ecotoxicity using tests performed on the ostracode Heterocypris incongruens and the fluorescent bacterium Vibrio fisheri. The tests confirmed the moderate-to-high ecotoxicity of aminophosphonates 3a-d and 4, but no evident correlation between the structure and toxicity has been found.