Papers by Sebastian Beckers
Advanced Science, May 29, 2019
Advanced Science, Aug 1, 2019
ACS Sustainable Chemistry & Engineering, Dec 8, 2020
Lignin is a promising feedstock in sustainable formulations for agrochemicals not only because of... more Lignin is a promising feedstock in sustainable formulations for agrochemicals not only because of its biodegradability but also because the biopolymer occurs naturally in the cell wall of plants and therefore is renewable and abundant. We used different lignin sulfonates to prepare stable aqueous dispersions of lignin nanocarriers loaded with agrochemicals by interfacial crosslinking in a direct miniemulsion. Despite the differences in structure and functionality, different lignin sulfonates were successfully methacrylated and degrees of methacrylation (>70%) were achieved. The resulting methacrylated lignin sulfonates were watersoluble and exhibited interfacial activity; they were used as reactive surfactants to stabilize oil droplets (cyclohexane or olive or rapeseed oil) loaded with a dithiol cross-linker [EDBET, 2,2′-(ethylenedioxy)bis(ethylthiol)] and a hydrophobic cargo (the fluorescent dye 1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene or the commercial fungicides prothioconazole and pyraclostrobin). After the addition of a water-soluble base, the thia-Michael addition was initiated at the droplet interface and produced lignin sulfonate nanocarriers with a core−shell structure within oily core and a cross-linked shell. Nanocarriers with diameters of ca. 200−300 nm were prepared; encapsulation efficiencies between 65 and 90% were achieved depending on the cargo. When the amount of the cross-linker was varied, the resulting lignin nanocarriers allowed a controlled release of loaded cargo by diffusion over a period of several days. The strategy proves the potential of lignin sulfonates as a feedstock for delivery systems for advanced plant protection.
ACS Biomaterials Science & Engineering, Aug 29, 2017
Lignin is an abundant biopolymer that is mainly burned for energy production today. However, usin... more Lignin is an abundant biopolymer that is mainly burned for energy production today. However, using it as a polyfunctional macromolecular building block would be desirable. Herein, Kraft lignin was modified through esterification of its hydroxyl groups with methacrylic anhydride. Then lignin nanocarriers with different morphologies (solid nanoparticles, core−shell structures, porous nanoparticles) were produced by a combination of miniemulsion polymerization and a solvent evaporation process. A UV-active cargo is used as a drug model to investigate the release behavior of the lignin nanocarriers depending on their morphology. To prove the enzymatic response of the lignin nanocarriers, we tested the enzyme laccase as a trigger to release the encapsulated cargo. Furthermore, porous lignin nanoparticles with high surface area were produced by carbonization. The carbon material has a high potential as an adsorbent, which was studied by adsorption tests with methylene blue. These biodegradable nanocarriers based on the polyfunctional bioresource lignin may find useful application as novel drug delivery vehicle in agriculture or as carbon materials for water purification.
Biopolymers, Dec 1, 2020
The delivery of agrochemicals is typically achieved by the spraying of fossil-based polymer dispe... more The delivery of agrochemicals is typically achieved by the spraying of fossil-based polymer dispersions, which might accumulate in the soil and increase microplastic pollution. A potentially sustainable alternative is the use of biodegradable nano-or micro-formulations based on biopolymers, which can be degraded selectively by fungal enzymes to release encapsulated agrochemicals. To date, no hemicellulose nanocarriers for drug delivery in plants have been reported. Xylan is a renewable and abundant feedstock occurring naturally in high amounts in hemicellulose-a major component of the plant cell wall. Herein, xylan from corncobs was used to produce the first fungicide-loaded xylan-based nanocarriers by interfacial polyaddition in an inverse miniemulsion using toluene diisocyanate (TDI) as a crosslinking agent. The nanocarriers were redispersed in water and the aqueous dispersions were proven to be active in vitro against several pathogenic fungi, which are responsible for fungal plant diseases in horticulture or agriculture. Besides, empty xylan-based nanocarriers stimulated the growth of fungal mycelium, which indicated the degradation of xylan in the presence of the fungi, and underlined the degradation as a trigger to release a loaded agrochemical. This first example of crosslinked xylan-based nanocarriers expands the library of biodegradable and biobased nanocarriers for agrochemical release and might play a crucial role for future formulations in plant protection.
Materials today bio, Jun 1, 2020
Antagonistic fungi such as Trichoderma reesei are promising alternatives to conventional fungicid... more Antagonistic fungi such as Trichoderma reesei are promising alternatives to conventional fungicides in agriculture. This is especially true for worldwide occurring grapevine trunk diseases, causing losses of US$1.5 billion every year, at which conventional fungicides are mostly ineffective or prohibited by law. Yet, applications of Trichoderma against grapevine trunk diseases are limited to preventive measures, suffer from poor shelf life, or uncontrolled germination. Therefore, we developed a mild and spore-compatible layer-by-layer assembly to encapsulate spores of a new mycoparasitic strain of T. reesei IBWF 034-05 in a bio-based and biodegradable lignin shell. The encapsulation inhibits undesired premature germination and enables the application as an aqueous dispersion via trunk injection. First injected into a plant, the spores remain in a resting state. Second, when lignindegrading fungi infect the plant, enzymatic degradation of the shell occurs and germination is selectively triggered by the pathogenic fungi itself, which was proven in vitro. Germinated Trichoderma antagonizes the fungal pathogens and finally supplants them from the plant. This concept enables Trichoderma spores for curative treatment of esca, one of the most infective grapevine trunk diseases worldwide.
Polymer Chemistry, 2021
Lignin is a highly abundant biopolymer that is a by-product formed during paper manufacturing. Li... more Lignin is a highly abundant biopolymer that is a by-product formed during paper manufacturing. Lignin is degraded by certain lignase-producing fungi and is relatively stable towards hydrolysis, which makes it an attractive material for diverse applications ranging from packaging to agrochemical delivery. However, a major challenge that hinders the large-scale use of lignin is its ill-defined chemical structure as a crosslinked copolymer with a variable comonomer composition, which results in strong batch-to-batch variations. To eradicate such a structural heterogeneity, herein, we synthesized two lignin-like monomers, comprising linkages found in native lignin, i.e., phenylcoumaran and β-O-4-aryl ether, and used them for the preparation of lignin-like nanocarriers by interfacial crosslinking in an inverse miniemulsion. The lignin-like monomers are accessible by a 2-or 4-step synthesis starting from bio-based compounds and can be prepared on a multigram scale. They carry hydroxyl groups, which reacted with toluene diisocyanate to produce lignin-like polyurethane nanocarriers with diameters between 200 and 400 nm. The nanocarriers might be used for the encapsulation of fungicides and for plant protection, as the lignin-like structure allowed the degradation by lignase-producing fungi, which are the cause of many plant diseases. Therefore, the dispersions might be of interest as a degradable drug delivery system, e.g. in advanced plant protection, or as synthetic alternatives to natural lignin. † Electronic supplementary information (ESI) available. See
Journal of Colloid and Interface Science, 2021
The current spraying of agrochemicals is unselective and ineffective, consuming a high amount of ... more The current spraying of agrochemicals is unselective and ineffective, consuming a high amount of fungicides, which endangers the environment and human health. Cellulose-based nanocarriers (NCs) are a promising tool in sustainable agriculture and suitable vehicles for stimuli-responsive release of agrochemicals to target cellulase-segregating fungi, which cause severe plant diseases such as Apple Canker. Herein, cellulose was modified with undec-10-enoic acid to a hydrophobic and cross-linkable derivative, from which NCs were prepared via thiol-ene addition in miniemulsion. During the crosslinking reaction, the NCs were loaded in situ with hydrophobic fungicides, Captan and Pyraclostrobin. NCs with average sizes ranging from 200 to 300 nm and an agrochemical-load of 20 wt% were obtained. Cellulose-degrading fungi, e.g. Neonectria. ditissima which is responsible for Apple Canker, lead to the release of fungicides from the aqueous NC dispersions suppressing fungal growth. In contrast, the non-cellulase segregating fungi, e.g. Cylindrocladium buxicola, do not degrade the agrochemical-loaded NCs. This selective action against Apple Canker fungi, N. ditissima, proves the efficacy of NC-mediated drug delivery triggered by degradation in the exclusive presence of cellulolytic fungi. Cellulose NCs represent a sustainable alternative to the current unselective spraying of agrochemicals that treats many crop diseases ineffectively.
Advanced Science, 2021
Spraying of agrochemicals (pesticides, fertilizers) causes environmental pollution on a million‐t... more Spraying of agrochemicals (pesticides, fertilizers) causes environmental pollution on a million‐ton scale. A sustainable alternative is target‐specific, on‐demand drug delivery by polymeric nanocarriers. Trunk injections of aqueous nanocarrier dispersions can overcome the biological size barriers of roots and leaves and allow distributing the nanocarriers through the plant. To date, the fate of polymeric nanocarriers inside a plant is widely unknown. Here, the in planta conditions in grapevine plants are simulated and the colloidal stability of a systematic series of nanocarriers composed of polystyrene (well‐defined model) and biodegradable lignin and polylactic‐co‐glycolic acid by a combination of different techniques is studied. Despite the adsorption of carbohydrates and other biomolecules onto the nanocarriers’ surface, they remain colloidally stable after incubation in biological fluids (wood sap), suggesting a potential transport via the xylem. The transport is tracked by flu...
Biopolymers, 2020
The delivery of agrochemicals is typically achieved by the spraying of fossil‐based polymer dispe... more The delivery of agrochemicals is typically achieved by the spraying of fossil‐based polymer dispersions, which might accumulate in the soil and increase microplastic pollution. A potentially sustainable alternative is the use of biodegradable nano‐ or micro‐formulations based on biopolymers, which can be degraded selectively by fungal enzymes to release encapsulated agrochemicals. To date, no hemicellulose nanocarriers for drug delivery in plants have been reported. Xylan is a renewable and abundant feedstock occurring naturally in high amounts in hemicellulose ‐ a major component of the plant cell wall. Herein, xylan from corncobs was used to produce the first fungicide‐loaded xylan‐based nanocarriers by interfacial polyaddition in an inverse miniemulsion using toluene diisocyanate (TDI) as a crosslinking agent. The nanocarriers were redispersed in water and the aqueous dispersions were proven to be active in vitro against several pathogenic fungi, which are responsible for fungal ...
Materials Today Bio, 2020
Antagonistic fungi such as Trichoderma reesei are promising alternatives to conventional fungicid... more Antagonistic fungi such as Trichoderma reesei are promising alternatives to conventional fungicides in agriculture. This is especially true for worldwide occurring grapevine trunk diseases, causing losses of US$1.5 billion every year, at which conventional fungicides are mostly ineffective or prohibited by law. Yet, applications of Trichoderma against grapevine trunk diseases are limited to preventive measures, suffer from poor shelf life, or uncontrolled germination. Therefore, we developed a mild and spore-compatible layer-by-layer assembly to encapsulate spores of a new mycoparasitic strain of T. reesei IBWF 034-05 in a bio-based and biodegradable lignin shell. The encapsulation inhibits undesired premature germination and enables the application as an aqueous dispersion via trunk injection. First injected into a plant, the spores remain in a resting state. Second, when lignindegrading fungi infect the plant, enzymatic degradation of the shell occurs and germination is selectively triggered by the pathogenic fungi itself, which was proven in vitro. Germinated Trichoderma antagonizes the fungal pathogens and finally supplants them from the plant. This concept enables Trichoderma spores for curative treatment of esca, one of the most infective grapevine trunk diseases worldwide.
Advanced Science, 2019
Nanocarrier (NC)‐mediated drug delivery is widely researched in medicine but to date has not been... more Nanocarrier (NC)‐mediated drug delivery is widely researched in medicine but to date has not been used in agriculture. The first curative NC‐based treatment of the worldwide occurring grapevine trunk disease Esca, with more than 2 billion infected plants causing a loss yearly of $1.5 billion, is presented. To date, only repetitive spraying of fungicides is used to reduce chances of infection. This long‐term treatment against Esca uses minimal amounts of fungicide encapsulated in biobased and biodegradable lignin NCs. A single trunk injection of <10 mg fungicide results in curing of an infected plant. Only upon Esca infection, ligninolytic enzymes, secreted by the Esca‐associated fungi, degrade the lignin NC to release the fungicide. The specific antifungal activity is confirmed in vitro and in planta (in Vitis vinifera L. cv. ‘Portugieser’). All treated plants prove to exhibit significantly fewer symptoms several weeks after treatment, and their condition is monitored for 5 years...
ACS Biomaterials Science & Engineering, 2017
Lignin is an abundant biopolymer that is mainly burned for energy production today. However, usin... more Lignin is an abundant biopolymer that is mainly burned for energy production today. However, using it as a polyfunctional macromolecular building block would be desirable. Herein, Kraft lignin was modified through esterification of its hydroxyl groups with methacrylic anhydride. Then lignin nanocarriers with different morphologies (solid nanoparticles, core−shell structures, porous nanoparticles) were produced by a combination of miniemulsion polymerization and a solvent evaporation process. A UV-active cargo is used as a drug model to investigate the release behavior of the lignin nanocarriers depending on their morphology. To prove the enzymatic response of the lignin nanocarriers, we tested the enzyme laccase as a trigger to release the encapsulated cargo. Furthermore, porous lignin nanoparticles with high surface area were produced by carbonization. The carbon material has a high potential as an adsorbent, which was studied by adsorption tests with methylene blue. These biodegradable nanocarriers based on the polyfunctional bioresource lignin may find useful application as novel drug delivery vehicle in agriculture or as carbon materials for water purification.
ACS Sustainable Chemistry & Engineering, 2019
Yearly the mushroom industry generates several million tons of spent mushroom substrate (SMS), a ... more Yearly the mushroom industry generates several million tons of spent mushroom substrate (SMS), a mixture of composted soil and fungal mycelium, left after the mushroom harvest. Although containing valuable ingredients like carbohydrates, lignin, and diverse enzymes, the substrate is unutilized and causes immense disposal costs. In order to valorize SMS, it is essential to fractionate the complex mixture into its valuable components, which is a challenge for current biorefineries and has only been partly achieved. We have developed a novel biorefinery strategy in order to separate carbohydrates and soluble lignin from SMS. Therefore, SMS was subjected to two different extraction methods in order to break the insoluble biopolymer residues: A, a thermochemical treatment (water/basic or acidic catalyst) yielding a carbohydrate-enriched liquid fraction; B, an organosolv extraction (with ethanol/water) solubilizing mainly lignin. The carbohydrate fraction possesses surface-active properties and was investigated as a potential biobased surfactant. The soluble lignin fraction was used for the formation of nanocarriers via an inverse miniemulsion polymerization. The lignin-based nanocarriers were biodegradable by laccases, which renders them of high interest for drug delivery systems for advanced plant protection. This novel biorefinery is a powerful strategy for the upcycling of SMS into various high-value products.
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Papers by Sebastian Beckers