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Lignin-based nano- and microcarriers are a promising biodegradable drug delivery platform inside of plants. Many wood-decaying fungi are capable of degrading the wood component lignin by segregated lignases. These fungi are responsible for severe financial damage in agriculture, and many of these plant diseases cannot be treated today. However, enzymatic degradation is also an attractive handle to achieve a controlled release of drugs from artificial lignin vehicles. Herein, chemically cross-linked lignin nanocarriers (NCs) were prepared by aza-Michael addition in miniemulsion, followed by solvent evaporation. The cross-linking of lignin was achieved with the bio-based amines (spermine and spermidine). Several fungicides—namely, azoxystrobin, pyraclostrobin, tebuconazole, and boscalid—were encapsulated in situ during the miniemulsion polymerization, demonstrating the versatility of the method. Lignin NCs with diameters of 200–300 nm (determined by dynamic light scattering) were obtained, with high encapsulation efficiencies (70–99%, depending on the drug solubility). Lignin NCs successfully inhibited the growth of Phaeomoniella chlamydospora and Phaeoacremonium minimum , which are lignase-producing fungi associated with the worldwide occurring fungal grapevine trunk disease Esca. In planta studies proved their efficiency for at least 4 years after a single injection into Vitis vinifera (“Portugieser”) plants on a test vineyard in Germany. The lignin NCs are of high interest as biodegradable delivery vehicles to be applied by trunk injection against the devastating fungal disease Esca but might also be promising against other fungal plant diseases.

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Biocompatible polymeric nanoparticles are obtained via thiol-ene polymerization of a biobased monomer in miniemulsion. The α,ω-diene-diester monomer is synthesized through esterification reaction of a glycerol derivative, namely 1,3-propanediol, with 10-undecenoic acid, a long-chain diene carboxylic acid. In order to investigate how different monomeric structures behave toward thiolene polymerization in miniemulsion, two types of thiols are investigated: 1,4-butanedithiol and 2-mercaptoethyl ether. Poly(thioether-ester)s with weight average molecular weight up to 15 kDa (M n ) are obtained, depending on initiator concentration and types of surfactant and dithiol employed. Finally, biobased poly(thioether-ester) nanoparticles are submitted to cytotoxicity and hemolysis analyses. High cell viability and no significant changes in cell morphology are observed after the incubation on murine fibroblast (L929) and human cervical cancer cells (HeLa). Last, hemolysis assays revealed blood compatibility and therefore polymeric nanoparticles have been shown to be a potential alternative drug delivery vector for intravenous administration. Practical Applications: There is a great demand for polymeric systems that fulfill a number of requirements, such as biodegradability and biocompatibility, for biomedical applications. In this context, biobased polymers obtained from vegetable oils are a very attractive sustainable alternative to fossil-derived polymeric materials, presenting potential biodegradability and low toxicity. By thiol-ene reactions, polymeric materials containing ester groups in the main chain -which can undergo hydrolysis-can be prepared in miniemulsion, enabling their degradation in physiological environment and, therefore, being interesting for biomedical applications and material disposal. Such novel materials could be used in temporary implants, tissue engineering, and drug delivery systems.

This work shows a method to synthesize and encapsulate magnetic nickel nanocrystals into polymeric colloidal particles through miniemulsion polymerization. The nickel nanoparticles are produced by a thermal decomposition method in the presence of oleylamine and triphenylphosphine, which results in a hydrophobic surface. However, being compatible with the monomer does not ensure a successful encapsulation by miniemulsion polymerization, as the nickel nanoparticles are expelled from the polymer particles with increasing styrene conversion due to the poor adhesion interaction between the organic shells of the nickel nanoparticles and the polystyrene. Changing the hydrophobic polystyrene to a polymer with higher polarity such as poly(methyl methacrylate) proves to be efficient for encapsulation of nickel nanoparticles when employing a hydrophilic initiator. After encapsulation, these nanoparticles show magnetic response.

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