Purpose: This study investigated the antibacterial activity of catechin-Zn complex entrapped β-CS nanoparticles (NPs) prepared at different particle sizes.
Methods: Catechin-Zn complex entrapped β-CS NPs were prepared with particle sizes of 208.0, 479.3, and 590.7 nm under different ratios of CS and catechins-Zn complex of 1:1, 1:3, and 1:5. Catechin-Zn complex were encapsulated by β-CS NPs using ionic gelation technology with sodium tripolyphosphate. Polydispersity index (PDI) and Zeta-potential were investigated for evaluating the homogeniousity of prepared nanoparticles. Strain growth curves, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) against L. innocua and E. coli were also evaluated for catechin-Zn complex entrapped β-CS NPs prepared at different particle sizes. One-way ANOVA and post-hoc least significant difference (LSD) test and Student-Newman-Keuls test (S-N-K) were used to determine significant treatment differences among treatments using SPSS program (P < 0.05).
Results: Prepared catechin-Zn entrapped β-CS NPs had PDI of 0.377-0.395, indicating good distribution of the nanoparticles, and positive Zeta-potential of 39.17-45.62 mV. The growth rate of L. innocua and E. coli treated by catechin-Zn complex entrapped β-CS NPs was slower than that without any treatment. MIC and MBC of catechin-Zn complex entrapped β-CS NPs at the smallest particle size of 208.0 nm against L. innocua and E. coli were 0.0625 and 0.125 and 0.03125 and 0.0625 mg/ml, respectively, which were significantly lower than those prepared at larger particle sizes.
Significance: This study demonstrated that catechins-Zn complex entrapped β-CS NPs can be used as a potential antibacterial substance for food and other applications, and their antibacterial activity can be enhanced by reducing particle size.