Dual-Carrier Armor for Pesticides: A β-Cyclodextrin/Starch Ester Nanoencapsulation System Enables Smart, Sustainable Delivery of Beta-Cypermethrin

Abstract

A β-cypermethrin (CY) nanoformulation (CY@β-CDs/SE) was constructed via a dual-carrier coencapsulation strategy utilizing β-cyclodextrin octadecanoate (β-CDs) and starch hexadecanoate ester (SE). This system leverages the host–guest inclusion of pesticide molecules within the hydrophobic cavity of β-CDs, followed by assembly with SE into an outer barrier via hydrophobic interactions between β-CD and SE side chains, supplemented by van der Waals forces and interfacial hydrogen bonding. The formulation significantly enhanced the stability of the active ingredient, exhibiting a thermal storage degradation of 3.47%, which was 20.4% and 59.0% lower than those of the single-carrier CY@β-CDs and CY microemulsion (CYm), respectively. The photolysis half-life (T50) of CY@β-CDs/SE reached 76.2 h, representing a 75% and 127% extension compared to CY@β-CDs and CYm, respectively. Sustained-release studies demonstrated a cumulative release of 79.0% after 302 h in 20% methanol–water, and release increased markedly under alkaline (pH = 9) or elevated temperatures (45 °C), with dual pH/temperature-responsive behavior. CY@β-CDs/SE maintained 68% insecticidal lethality 25 days postapplication, outperforming CY@β-CDs (48.0%) and CYm (34.7%). Furthermore, CY@β-CDs/SE substantially improved the biosafety of β-cypermethrin, achieving a 96h LC50 value of 24.7 μg/L in zebrafish, 2.1-fold higher than that of CYm (11.7 μg/L), while also enhancing the biosafety for rice seed germination. This study establishes an intelligent delivery system using biodegradable materials, offering a strategy for pesticide reduction and advancing sustainable agricultural practices.