Coumarin-Containing Light-Responsive Carboxymethyl Chitosan Micelles as Nanocarriers for Controlled Release of Pesticide

Abstract

Currently, controlled release formulations (CRFs) of pesticides in response to biotic and/or abiotic stimuli have shown great potential for providing “on-demand” smart release of loaded active ingredients. In this study, amphiphilic biopolymers were prepared by introducing hydrophobic (7-diethylaminocoumarin-4-yl)methyl succinate (DEACMS) onto the main chain of hydrophilic carboxymethylchitosan (CMCS) via the formation of amide bonds which were able to self-assemble into spherical micelles in aqueous media and were utilized as light-responsive nanocarriers for the controlled release of pesticides. FTIR and NMR characterizations confirmed the successful synthesis of the CMCS-DEACMS conjugate. The critical micelle concentration (CMC) decreased with the increase in the substitution of DEACMS on CMCS, which ranged from 0.013 to 0.042 mg/mL. Upon irradiation under simulated sunlight, the hydrodynamic diameter, morphology, photophysical properties and photolysis were researched by means of dynamic light scattering (DLS), transmission electron microscopy (TEM), UV-vis absorption spectroscopy and fluorescence spectroscopy. Moreover, 2,4-dichlorophenoxyacetic acid (2,4-D) was used as a model pesticide and encapsulated into the CMCS-DEACMS micelles. In these micelle formulations, the release of 2,4-D was promoted upon simulated sunlight irradiation, during which the coumarin moieties were cleaved from the CMCS backbone, resulting in a shift of the hydrophilic–hydrophobic balance and destabilization of the micelles. Additionally, bioassay studies suggested that this 2,4-D contained which micelles showed good bioactivity on the target plant without harming the nontarget plant. Thereby, the light-responsive CMCS-DEACMS micelles bearing photocleavable coumarin moieties provide a smart delivery platform for agrochemicals.

Nanomaterials as Nanofertilizers and Nanopesticides: An Overview

“…[133] They are also seen as effective insecticides which can be used and they also ensure controlled release to avoid harming the environment. [139] In this regard, Feng et al [140] shown the effect role of 2,4-dichlorophenoxyacetic (2,4-D) herbicide loaded into coumarin-containing carboxymethyl chitosan micelles as nanocarrier in on target plant without negative effect on the non-target plant. Furthermore, Zhang et al [139a] by using polyethylene glycolcamptothecin polymer which assembles into nanomicelle exhibited their excellent insecticidal potential against Brevicoryne brassicae, Tetranychus cinnabarinus, and Bursaphelenchus xylophilus.…”

Chitosan Functionalization: Covalent and Non-Covalent Interactions and Their Characterization

“…The reverse synthetic pathway was also reported in the literature: the substrate of interest was first derivatized with an anhydride, followed by the grafting of the resulting system onto amino groups of CS via EDC.HCl/NHS or similar reagents [ 45 ].…”

Biodegradable and Light-Responsive Polymeric Nanoparticles for Environmentally Safe Herbicide Delivery

“…Stimuli-responsive polymers, which can display a sharp change of chemical or physical properties after the treatment of stimuli, were broadly used to encapsulate pesticides. , Many stimuli-responsive controlled-release pesticide systems were developed based on abiotic and biotic stimuli, such as light, − temperature, , pH, − reactive oxygen species (ROS), redox, , and enzymes. − Among them, light-cleavable polymers attract growing attention because light provides a possible platform for achieving drug release in a remote and spatiotemporal controlled way by facilely adjusting the energy, wavelength, and site of irradiation. − Light-responsive controlled-release pesticide systems hold great potential in agricultural fields because there is abundant sunlight irradiation in open lands, which is clean and sustainable ,− Ding et al developed an amphiphilic polymer–pesticide conjugate that 2,4-D was covalently conjugated with water-soluble PEG by a photolabile o -nitrobenzyl group as a linker.…”