This presentation will showcase the development of sustainable and environmentally friendly alternatives to conventional encapsulation methods for agrochemicals or biological control agents. Our research focuses on designing and synthesizing biobased and/ or biodegradable polymers, including lignin-based materials and polyphosphoesters, for the controlled release of plant protection agents in planta or ensuring rainfastness on the leaves. Either emulsion formulation, layer-by-layer strategies, or block copolymer self-assembly in the presence of agrochemicals or fungal spores was used in several examples by our team and this presentation will summarize our recent efforts in making plant protection more sustainable and free of non-degradable microplastics.

Chemical pesticides have become an inevitable evil of modern agriculture, ensuring food security despite their undesired consequences, such as human sickness, increased pesticide resistance, and harm to non-target organisms. While scientists strive to mitigate this damage, nature has developed defense mechanisms to protect itself. Trichomes are hair-like leaf appendages on some plants that can secrete adhesive compounds to physically trap insects. Inspired by this natural strategy, we attempt to imitate this sticky exudate from trichomes using polymer solutions.

In our proof-of-concept study, we demonstrated the feasibility of a biopolymer in a natural deep eutectic solvent as a non-toxic alternative to chemical pesticides. Oscillatory shear studies revealed insights into the viscoelastic nature of the trichome-inspired materials. Dilution with water improved solution processability, confirmed through steady shear rheology. Adhesiveness was evaluated using force measurements from a custom indentation setup, showing promising adhesion for a minimum of one week. Tack measurements revealed remarkable adhesion energies and the formation of long fibrils during retraction, extending up to a few centimeters. These strong fibrils ensure trapped insects cannot escape easily. Using western flower thrips, Frankliniella occidentalis (Pergande), as model subjects, behavioral experiments showed significantly reduced motion on the sample, with adult thrips and larvae immobilized in the droplets.

This study introduces a novel class of materials inspired by nature that could advance integrated pest management, harnessing the expertise of the ultimate innovator – nature itself.

Many objects in the human environment are made of various types of plastics. These objects crumble and abrade, causing micro- and nanoplastics to form. Plastic has become a common environmental pollutant, but its impact on living organisms is still unknown [1].
Our group is conducting a study in which we want to find out whether nanoplastic found in the environment of microorganisms is absorbed by them. We have developed nano-poly(ethylene terephthalate) (PET) labelled with upconverting nanoparticles (UCNPs). These particles exhibit the upconversion phenomenon, i.e. they absorb radiation of lower energy and emit light of higher energy [2]. This property of plastic tracers has enabled us to visualize plastic in biological materials.
NanoPET labelled UCNPs were obtained by dissolution in organic solvent followed by precipitation. The resulting colloids were purified by membrane dialysis. The efficiency of purification was checked by FTIR analysis. The size of the nanoplastic was determined by DLS analysis. A fluorescence microscope and plate reader were used to visualise the labelled nanoPET. The study helped to assess whether the labelled nanoPET penetrates into selected freshwater organisms.
The work was supported by the National Science Centre, Poland, under research project OPUS 23 2022/45/B/ST5/00604.

Microalgae are a promising CO2-fixing feedstock which is gaining growing attention for the production of biofuel, the extraction of valuable fatty acids, and other high value chemicals. Despite the great potential of microalgae, their production and especially the isolation of the biomass remains economically unsustainable due to the high energy cost for harvesting. Since microalgae carry an overall negative surface charge, sedimentation can be induced by addition of cationic flocculants, which is a common harvesting technique. The presented work will investigate the structural impact of polymeric flocculants by assessing different macromolecular architectures. RAFT polymerisation of commercially available 2-(dimethylamino)ethyl methacrylate (DMAEMA) is demonstrated to be a suitable technique for the synthesis well-defined linear polymers of different lengths. The polymer library is thoroughly analysed in order to confirm their absolute structure, molecular weight and solution properties. Furthermore, the results of flocculation tests on fresh- and salt water algae under various conditions are presented and a relationship between polymer architecture and flocculation efficiency is assessed. Furthermore, the mechanism of flocculation is discussed using atomic force microscopy.

Gene therapy is one of the latest therapeutic approaches against various diseases and genetic conditions. For the successful delivery of genes, a polymeric carrier should offer essential advantages like enhanced stability, protection from nuclease degradation and facilitation of cellular entry [1]. In this respect, natural polysaccharides like chitosan offer great potential to be utilized as non-viral vectors owing to their intrinsic biocompatibility, biodegradability, low toxicity, and cationic charge. Moreover, they can be easily chemically modified, e.g. through grafting, leading to hybrid synthetic-biological copolymers with additional functionalities [2,3].
This work concerns the co-assembly between a chitosan-graft-poly(N-isopropylacrylamide) (Chit-g-PNIPAM) copolymer and DNA molecules of different lengths, towards the construction of polyplexes that can serve as potential gene delivery systems [4]. The amino groups of the chitosan backbone enable electrostatic binding with the oppositely charged phosphate groups of the DNA chains, while the PNIPAM side chains impart thermoresponsiveness to the system. Different N/P (amino to phosphate groups) mixing ratios were examined aiming to produce stable polyplexes. The mass, size, size distribution and effective charge of the resulting nanoassemblies were investigated by dynamic and electrophoretic light scattering (DLS and ELS), while their morphology was studied by electron microscopy (STEM). Moreover, their response to changes in their environment, namely temperature and ionic strength, as well as their stability against biological media was also examined. Finally, the DNA binding affinity of the copolymer was evaluated through fluorescence spectroscopy and EtBr quenching assays, while the structure of the complexed DNA chains was assessed by infrared spectroscopy.