Enzyme Stimuli–Responsive Nanoparticles for Bioinsecticides: An Emerging Approach for Uses in Crop Protection

Abstract

The encapsulation of pesticides in systems responsive to enzymes allow for greater selectivity and specificity in pest control, in addition to contributing to reducing the impact on nontarget organisms and the environment. Therefore, the objective of this study was to investigate the synthesis of zein nanoparticles loaded with a mixture of botanical insecticides with release triggered by proteolytic enzymes found in the midguts of insects and larvae. The synthesis of the nanoparticles was carried out using the antisolvent precipitation method. Nanoformulations were characterized according to size, zeta potential, encapsulation efficiency, matrix and active ingredients interaction, and morphology. The enzymatic degradation was then studied. Nanoformulations have excellent encapsulation efficiency, greater than 95%, and stability over 60 days. The enzymatic tests showed significant reduction of the initial concentration of nanoparticles in 60 min and improved the release of geraniol, which increased from 15% to 56% in the presence of trypsin. Thus, the proteolytic enzymes were able to break down zein nanoparticles and stimulate the release of active ingredients providing a significant perspective for the control of crop insects.

Temperature-Switchable Polymer: Uniting Deep Eutectic Solvents with Poly(N-isopropylacrylamide) and Poly(N-vinyl caprolactam)

“…Thermoresponsive polymers (TRPs) have gained the interest of the scientific community because of their fascinating properties (as smart biomaterials). TRPs hold the potential to upgrade the quality life of humans in different fields through their use and development of biosensors, immune analysis, antifouling agents, drug delivery, and actuators for artificial muscles. − TRPs can be considered the most promising materials in phase-transition systems and are capable of undergoing a reversible phase transition from hydrophilic to hydrophobic conformation which can be influenced by the presence of foreign components such as proteins, osmolytes, salts, or the presence of cosolvents. − Phase separation of aqueous solutions of TRPs is generally associated with the temperature-dependence of the inter- and intramolecular H-bonding and hydrophobic interactions in the polymer chains. ,,− Over the past 20 years, ionic liquids (ILs) have been recognized as a “‘green’” (environmentally friendly) alternatives to traditional organic solvents due to their specific properties such as low melting points, negligible vapor pressures, nonflammability, high thermal stability, wide electrochemical window, high solubility, structural tuneability, and excellent ionic conductivity, among others. ,− ,,− Several studies have demonstrated the suitability of ILs as potential media for supporting the phase transition of TRPs. ,,, The temperature sensitivity of poly­( N -isopropylacrylamide) (PNIPAM) varies significantly in the presence of different ILs. ,, However, the cost and complexity of preparing ILs and, in some cases, the poor biodegradability of ILs, have been recognized as their main drawbacks …”

Nano-pesticides: the lunch-box principle—deadly goodies (semio-chemical functionalised nanoparticles that deliver pesticide only to target species)

“…In this approach, if a pest organism is attracted to the lunch-box, it must then “open” it, which requires that the carrier is made of a palatable/digestible material, e.g., cellulose or pectin. The “opening” could be triggered by gut digestive enzymes or physical–chemical parameters [ 48 – 50 ]. Hence, the material properties are important for the carrier’s stability, the potential to be opened, and, in particular, the timing of the box’s opening is crucial.…”

Gel Carriers for Plant Extracts and Synthetic Pesticides in Rodent and Arthropod Pest Control: An Overview

“…For that reason, it is important to develop formulations that ensure greater stability and controlled release of the natural substances. Mechanisms of improving essential oil stability include various encapsulation techniques of natural substances by formulating them as nano- and microemulsions [ 131 ], microspheres [ 132 ], and nanoparticles [ 133 ]. The use of highly sorptive hydrogels may also provide higher and longer activity of essential oils applied as pesticides and repellents [ 46 , 98 , 134 ].…”