ROS-responsive modified chitosan oligosaccharide nanocapsules for improving pesticide efficiency and intelligent release

Fe-based metal-organic frameworks modified with carboxymethyl cellulose for targeted pesticide delivery and reducing biotoxicity

Traditional pesticide formulations have issues such as poor targeting, low adhesion performance, and a tendency to leach into the environment, causing pollution. In this study, a pesticide delivery platform (PRO@FeMOFs@CMC) with a dual response was designed by encapsulating prochloraz technical (PRO) within Fe-based metal-organic frameworks (FeMOFs) and using carboxymethyl cellulose (CMC) as the gatekeeper. The results showed that PRO@FeMOFs@CMC exhibited a loading capacity of 28.86 % for PRO and efficient adhesion to wheat and rice leaves. This delivery platform showed a significant increase in the release of PRO under environments similar to that produced by a pathogen infection, involving cellulase and glutathione (GSH). Importantly, compared to prochloraz suspension concentrate (PRO@SC), PRO@FeMOFs@CMC exhibited higher fungicidal efficacy against Rhizoctonia cereali and Rhizoctonia solani and its acute toxicity to zebrafish and earthworms was reduced by 3.7 times and 8.6 times, respectively. Compared to PRO@SC, the cells treated with PRO@FeMOFs@CMC had higher cell viability and a significantly reduced apoptosis rate, demonstrating greater safety. Additionally, FeMOFs@CMC showed no evident toxicity to wheat and rice. In summary, PRO@FeMOFs@CMC is an efficient and safe pesticide controlled-release system for the sustainable management of wheat and rice diseases.

Layer-by-layer assembled decomposable nanocapsules for light-responsive release of pesticide imidacloprid on Aphis craccivora Koch

BACKGROUND

Conventional pesticide formulations are often inefficient because of low biological uptake after spraying. Controlled release nanopesticides can release pesticides precisely in response to specific stimuli, thereby killing pests and pathogens using the least effective concentration. This study aims to develop nanocapsule-based photo-decomposable nanopesticides for efficient pesticide control.

RESULTS

The target nanopesticides were successfully fabricated using layer-by-layer assembly of the negative azobenzene-grafted hyaluronic acid (azo-HA) and positive polydimethyldiallylammonium chloride (polyDADMAC), confirmed by UV-visible, dynamic light scattering, Zeta potential and transmission electron microscopy measurements. The particle size and Zeta potential of the fabricated nanocapsules were 220 nm and +46.1 mV, respectively, and the nanocapsules were found to remain stable for up to 30 days. The optimized drug loading and encapsulation ratio of imidacloprid (IMI) in IMI/azo-HA@polyDADMAC were 21.5% and 91.3%, respectively. Cumulative release of IMI from the nanopesticides increased from ~50% to ~95% upon UV light irradiation (365 nm). The half lethal concentration (LC50) value of the nanopesticides toward Aphis craccivora Koch decreased from 2.22 to 0.55 mg L-1 upon UV light irradiation.

CONCLUSION

The trans to cis transformation of the azo group in HA decomposed IMI/azo-HA@polyDADMAC nanopesticides upon UV irradiation, thus facilitating the release of IMI, resulting in a decrease in the concentration of pesticides required for efficient pesticide control. Our work demonstrated the great potential of light-responsive nanocapsules as a controlled release nanocarrier for efficient and eco-friendly pesticide control in sustainable agriculture. © 2024 Society of Chemical Industry.

Advances in the preparation, characterization, and biological functions of chitosan oligosaccharide derivatives: A review

Chitosan oligosaccharide (COS), which represent the positively charged basic amino oligosaccharide in nature, is the deacetylated and degraded products of chitin. COS has become the focus of intensive scientific investigation, with a growing body of practical and clinical studies highlighting its remarkable health-enhancing benefits. These effects encompass a wide range of properties, including antibacterial, antioxidant, anti-inflammatory, and anti-tumor activities. With the rapid advancements in chemical modification technology for oligosaccharides, many COS derivatives have been synthesized and investigated. These newly developed derivatives possess more stable chemical structures, improved biological activities, and find applications across a broader spectrum of fields. Given the recent interest in the chemical modification of COS, this comprehensive review seeks to consolidate knowledge regarding the preparation methods for COS derivatives, alongside discussions on their structural characterization. Additionally, various biological activities of COS derivatives have been discussed in detail. Lastly, the potential applications of COS derivatives in biomedicine have been reviewed and presented.