Temperature-Responsive Pyraclostrobin-Loaded Octadecane Submicrocapsules with Lowered Toxicity

Abstract

Pyraclostrobin (Pyr) is one of the most effective fungicides. However, it can degrade via photolysis in water, it is toxic to aquatic life and if inhaled, it has a low solubility in water, that leads to difficulties when applying to plants by spraying. Additionally, the necessity of repeated (weekly) sprays of fungicides when the pathogen growth risk is the highest, such as at the temperature range of 24 to 36 °C and increased humidity of about 95%, leads to loss of efficiency of the fungicide and overdose of chemicals. In the present study, pyraclostrobin was microencapsulated to solve the abovementioned issues. As a core of capsules octadecane (OD) with a melting point of 28 °C was used, thus, the release of pyraclostrobin was controlled via temperature change. Pyraclostrobin-loaded submicrocapsules (PyrSMCs) were characterized using SEM, DLS, TGA/DSC, HPLC, FTIR methods; stimuli-responsivity was tested employing in vitro tests with pathogenic culture (Fungal strain of Pyrenophora teres - CPPF-453) grown in Petri dishes. Toxicity of PyrSMCs to Artemia salina was studied as well. Size of capsules was 200–600 nm along with the presence of bigger capsules with a diameter of 1–4 µm. PyrSMCs showed excellent antifungal effects above the melting point of octadecane. PyrSMCs demonstrated 29 times less toxicity than pyraclostrobin of technical grade. Overall, results show the potential of such capsules to be applied in the agricultural industry for precise agriculture strategies.

Photothermal controlled‐release microcapsule pesticide delivery systems constructed with sodium lignosulfonate and transition metal ions: construction, efficacy and on‐demand pesticide delivery

“…In recent years, microencapsulation technology was adopted to encapsulate pesticide active ingredients in micro–nano capsule systems and protect them from the effects of surrounding environmental factors, hence effectively improving the utilization efficiency of pesticides 5,6 . Currently, controlled‐release microcapsule pesticides have received extensive attention because the release of pesticide active ingredients can be effectively regulated by external stimuli‐responsive conditions such as pH, 7 temperature, 8 magnetism, 9 microbe, 10 near‐infrared (NIR), 11 ultraviolet (UV) light 12 and enzymes 13 . Recently, a few photothermally controlled‐release microcapsule pesticide‐delivery systems have been reported 14 .…”

Nanofibrous membranes with hydrophobic and thermoregulatory functions fabricated by coaxial electrospinning

“…18,19 Oct is a commonly used organic PCM, which has attracted wide attention due to its high heat storage, great thermal stability, non-toxicity, and phase transition temperature close to human body temperature. 20,21 To overcome the leakage problem of PCMs, fabric finishing, 22 microcapsule treatment 23,24 and coaxial electrospinning 25,26 are generally used to encapsulate them. The initial two methods are complex and inconvenient to use, with certain limitations.…”