Background
Polymeric particle formulations containing active ingredients have been developed in agriculture to protect plants from pathogens while reducing health risks and environmental impact. Chitosan (Ch), a biodegradable and non-toxic polymer, exhibits antimicrobial properties, while Curcumin (CUR), a natural turmeric compound, has recognized biocidal activity. Combining Ch and CUR may enhance antifungal performance against phytopathogenic fungi.

Methods
Biocomposite nanoparticles (CUR-loaded Ch-tripolyphosphate, CP-CUR) were synthesized via ionotropic gelation, achieving >90% CUR encapsulation. Particles were characterized by FESEM, FT-IR, XRD, and UV-Vis, revealing quasi-spherical morphology within Ch lamellar-like bundles (200 nm average). Antifungal assays were conducted on 2,500 conidia in 300 µL of Fusarium oxysporum, Fusarium fujikuroi and Alternaria solani using Ch, CP, CP-CUR (6.25, 12.5, 25 mg/mL) and CUR (200, 250, 300 µg/mL). Germination inhibition was assessed after three days of incubation.

Significant Findings

F. oxysporum was completely inhibited by Ch at 25 and 12.5 mg/mL, while CUR showed dose-dependent inhibition, reaching maximum at 300 µg/mL; CP and CP-CUR were ineffective. F. fujikuroi showed total inhibition at all Ch concentrations and with CP-CUR10, with CUR at 300 µg/mL reducing colony density. A. solani was resistant to Ch but inhibited by CUR from 200 µg/mL, showing no growth at 300 µg/mL; CP and CP-CUR slightly reduced colony size. These results indicate that free Ch is more effective against F. oxysporum and F. fujikuroi, while CUR is more potent against A. solani. High CUR release in CP-CUR could counteract chitosan’s effect, indicating that optimal formulation and concentration are key for maximizing antifungal performance.