Fungicide‐loaded and biodegradable xylan‐based nanocarriers

Abstract

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.

Lignin–Chitosan Nanocarriers for the Delivery of Bioactive Natural Products against Wood-Decay Phytopathogens

“…For P. chlamydospora, MICs of 5 µg•mL −1 were found in all cases. Comparable MICs < 10 µg•mL −1 against P. chlamydospora and Phaeoacremonium aleophilum were also reported by the same group for pyraclostrobin xylan-based nanocarriers [12]. When cellulose-based NCs loaded with pyraclostrobin (20-30 wt%) and captan (20-30 wt%) were used instead, MICs 5 and >50 µg•mL −1 were obtained, respectively [41].…”

“…Ligninderived compounds are useful as biodegradable building blocks for nanomaterials, and, in the past few years, some studies have presented lignin-based NCs [10]. Other bibliographic precedents include the work by Pathania et al [11] on the preparation of a chitosan-gpoly(acrylamide) nanocomposites by a simple method in the presence of microwaves; the study by Beckers et al [12] on the synthesis of xylan NCs employing toluene diisocyanate as a cross-linking agent (in which NCs were loaded with a synthetic fungicide); the investigations by Ciftci et al [13] on the synthesis of chitosan microcapsules containing glycidyl methacrylate terpolymer, maleic anhydride, and N-tert-butylacrylamide, and some other articles on the formation of lignin-chitosan films [14,15]. However, to the best of the authors' knowledge, there are no reports on the insertion of chitosan oligomers between lignins (Aradmehr and Javanbakht [16] described lignin-chitosan biocomposites, but the existence of covalent interactions between the groups was not evidenced).…”

Biomaterials Technology for AgroFood Resilience

“…Xylan‐based nanocarriers loaded with fungicides were reported to be active in vitro against several pathogenic fungi associated with plant diseases. [ 199 ] Interestingly, empty xylan‐based nanocarriers stimulated the growth of fungal mycelium, indicating the degradation of xylan in the presence of the fungi. This analogy to lignin makes it a candidate for infection‐responsive fungicide.…”

Recent Advances on Lignocellulosic-Based Nanopesticides for Agricultural Applications

“…However, several examples have been demonstrated in recent years. Beckers et al (2020a) described the first synthesis of nanocarriers built from xylan extracted from corn cobs to contain the fungicide pyraclostrobin, by interfacial polymerization method of diisocyanate of toluene (TDI) in an inverse emulsion. Hence, such nanopesticide was colloidally stable in water and cyclohexane for several weeks as well as it was efficient against phytopathogenic fungi (Botrytis cinerea) as the biocide release from the xylan nanocarriers was stimulated by the fungi.…”