Antibacterial Microfibrillated Cellulose as Stimuli-Responsive Carriers with Enhanced UV Stability for Sustained Release of Essential Oils and Pesticides

Plant essential oils and pesticides are commonly used methods for preventing and controlling agricultural pests and diseases. To address the challenges of volatility of essential oils and ultraviolet sensitivity of avermectin (AVM), herein, microfibrillated cellulose anchored with ammonium molybdate (MFC-POM) was constructed via the emulsion template method and the ion exchange process and applied as carriers for tea tree oils (TTO) and AVM to protect the active ingredients. The amount by anchoring of molybdenum oxygen cluster ions into cellulose skeleton was similar to 29.54%. MFC-POM exhibited a relatively high loading capacity for both TTO and AVM of 52.23 and 42.12%, respectively. Meanwhile, TTO@MFC-POM possessed a long-term sustained release behavior fitting with logistic release kinetics model and held enhanced antibacterial activity compared to pure TTO and MFC-POM. AVM@MFC-POM exhibited pH-responsive release behavior with more AVM release under acidic and alkaline conditions. Furthermore, AVM@MFC-POM presented remarkable ultraviolet light resistance with a half-life nearly 30 times longer. MFC-POM also represented superior wetting properties and a noticeable increase in liquid retention on cucumber foliar surfaces. AVM@MFC-POM retained insecticidal toxicity, provided trace nutrient element Mo, and promoted germination and plant growth, thus exhibiting good biological safety. Overall, MFC-POM could serve as an effective carrier for protecting active ingredients and improving their effectiveness for agricultural disease and pest control.