Chitosan‐basedorganic/inorganic composite engineered forUV light‐controlledsmartpH‐responsivepesticide throughin situphoto‐inducedgeneration of acid

Abstract

BACKGROUND: Confined by the volatile property, pesticides are overused and lost significantly during and after spraying, weakening the ecological microbalance among different species of lives. Acid-responsive pesticide is a type of smartly engineered pesticides that contribute to the improvement of utilization efficiency of pesticidal active ingredients in acid-controlled manner, whilst the implementation of acidic solutions may disturb the balance of microenvironment surrounding targeted plants or cause secondary pollution, underscoring the input of acid in a more precise strategy.RESULTS: Chitosan was chemically modified with a photoacid generator (2-nitrobenzaldehyde) serving as a light-maneuvered acid self-supplier, based on which a smart pesticide was formulated by the integration of attapulgite and organophosphate insecticide chlorpyrifos. Under the irradiation of UV light (365 nm), the modified chitosan would undergo a photolytic reaction to generate an acid and pristine chitosan, which seized the labile protons and facilitated the release of chlorpyrifos based on its inherent pH-responsive flexibility. According to the pesticide release performance, the release rate of chlorpyrifos under UV light (27.2 mW/cm 2 ) reached 78%, significantly higher than those under sunlight (22%, 4.2 mW/cm 2 ) and in the dark (20%) within the same time, consistent with the pH reduction to 5.3 under UV light and no obvious pH change for the two other situations, exhibiting an attractive UV light-controlled, acid-propelled release behavior.CONCLUSION: Compared to direct acid spray approach, the proposed in situ photo-induced generation of acid locally on the spots of applied pesticide circumvents the problem of acid contamination to nontargets, demonstrating higher efficiency and biocompatibility for the controlled delivery of acid-responsive pesticides and pest management.

Recent Advances in Stimulus-Responsive Nanocarriers for Pesticide Delivery

“…On the other hand, certain fungi, like Fusarium acnes , secrete organic acids during their growth and reproduction, which can degrade plant tissues and reduce environmental acidity. , Drawing from such insights, numerous researchers devised various pH-responsive carriers for pesticide loading. These carriers can effectively control the release of pesticides by capitalizing on pH changes induced by the infected target organism. − …”

Recent Advances in Nanoparticle-Mediated Co-Delivery System: A Promising Strategy in Medical and Agricultural Field

“…The stimulus-responsive nanocarriers typically employ widely available and biodegradable natural polymers including ethyl cellulose and starch. Liu et al developed a composite that chemically functionalized chitosan and attapulgite clay as pesticide carriers capable of responding to UV-accelerated release [ 100 ]. The release of the pesticide under UV light stimulation is 3.5 times that under natural light, demonstrating a good performance of light-controlled release of the smartly engineered pesticide.…”

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

“…4,8,9 To date, scientists have developed a variety of controlled release nanopesticides that can respond to pH, temperature, enzyme, reactive oxygen species and light. [10][11][12][13] Light-responsive nanopesticides are often favored because of the unique advantages of light, such as clean, cost-effective and adjustable parameters. The release of active ingredients from nanopesticides can be triggered through the ultraviolet (UV) light-induced cleavage/isomerization of chemical bonds or near infrared (NIR) photothermal conversion-induced phase change in coating materials.…”