Difenoconazole-Loaded Nanostructured Lipid Carriers: Preparation, Characterization, and Evaluation

Yinghong Li; Hu Zhang; Tingting Meng; Yuqin Zhou; Beilei Zhou; Shihan Du; Hong Yuan; Fuqiang Hu

doi:10.3390/ph18060780

Difenoconazole-Loaded Nanostructured Lipid Carriers: Preparation, Characterization, and Evaluation

Pharmaceuticals (Basel). 2025 May 23;18(6):780. doi: 10.3390/ph18060780.

Authors

Yinghong Li^{1

2}, Hu Zhang³, Tingting Meng¹, Yuqin Zhou⁴, Beilei Zhou², Shihan Du⁴, Hong Yuan¹, Fuqiang Hu¹

Affiliations

¹ College of Pharmaceutical Science, Zhejiang University, No. 866 Yuhangtang Road, Hangzhou 310058, China.
² Zhejiang Institute for Food and Drug Control, NMPA Key Laboratory for Testing and Warning of Pharmceutical Microbiology, Zhejiang Key Laboratory of Biopharmaceutical Contact Materials, No. 325 Pingle Street, Hangzhou 310052, China.
³ Institute of Agro-Product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, No. 198 Shiqiao Road, Hangzhou 310021, China.
⁴ School of Pharmacy, China Pharmaceutical University, No. 639, Longmian Avenue, Nanjing 211198, China.

Abstract

Background/Objectives: Difenoconazole (DFC) is a broad-spectrum fungicide. However, its application is limited due to poor aqueous solubility. Drugs with low solubility can be better absorbed using nanostructured lipid carriers (NLCs). Hence, the application of DFC in an NLC delivery system is proposed. Methods: Difenoconazole-loaded nanostructured lipid carriers (DFC-NLCs) with different solid-liquid lipid ratios were prepared by solvent diffusion method. Key physicochemical parameters, including particle diameter, surface charge (zeta potential), drug encapsulation efficiency, and morphological characteristics, were systematically characterized. Using Rhizoctonia solani (R. solani) as the model strain, inhibitory efficiency of DFC-NLC dispersion was compared with that of commercial dosage forms, such as 25% DFC emulsifiable concentrate (DFC-EC) and 40% DFC suspension concentrate (DFC-SC). Additionally, uptakes of DFC-NLC dispersions in R. solani were further observed by fluorescence probe technology. The safety profiles of DFC-NLCs and commercial dosage forms were evaluated using zebrafish as the model organism. Acute toxicity studies were conducted to determine the maximum non-lethal concentration (MNLC) and 10% lethal concentration (LC₁₀). Developmental toxicity studies were performed to observe toxic phenotypes. Results: DFC-NLC dispersions were in the nanometer range (≈200 nm) with high zeta potential, spherical in shape with encapsulation efficiency 69.1 ± 1.8%~95.0 ± 2.6%, and drug loading 7.1 ± 0.3%~9.7 ± 0.6% determined by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Compared with commercial dosage forms, the antifungal effect of the DFC-NLC on R. solani was significantly improved in in vitro antibacterial experiments (p < 0.05). The 50% effective concentration (EC₅₀) values were 0.107 mg·L^-1 (DFC-NLC), 0.211 mg·L^-1 (DFC-EC), and 0.321 mg·L^-1 (DFC-SC), respectively. The uptakes of FITC-labeled DFC-NLC demonstrated that an NLC was appropriate to deliver DFC into pathogen to enhance the target effect. In safety assessment studies, DFC-NLCs exhibited a superior safety profile compared with commercial formulations (p < 0.05). Conclusions: This study investigates the feasibility of NLCs as delivery systems for poorly water-soluble fungicides, demonstrating their ability to enhance antifungal efficacy and reduce environmental risks.

Keywords: antifungal effect; difenoconazole; nanostructured lipid carriers; preparation; toxicity; zebrafish.