*3.5. Silver Ions Release of C. pentandra*/*Ag-NPs*

The antibacterial activity of Ag-NPs is related with the release of Ag<sup>+</sup> ions from Ag-NPs. In this study, the percentage of Ag<sup>+</sup> ions release rate was observed from 0 to 144 h. In 6 h, the percentage of Ag<sup>+</sup> ions release rate is 90% and increased to 97% after 144 h as shown in Figure 14. This result supports the potential of *C. pentandra*/Ag-NPs as an antibacterial activity over a long time and highly diffusive of Ag<sup>+</sup> ions to diffuse in the media and inhibit the bacteria growth. This Ag<sup>+</sup> ions release caused toxic to the cell of bacteria by generating reactive oxygen species (ROS) and finally caused death of bacteria [34]. Besides that, by supporting Ag-NPs in *C. pentandra* fiber can control the aggregation of the colloidal Ag-NPs which resulted to no bioactivity and bioavailability of Ag-NPs in the media and reduced their antibacterial activity. The usage of Ag-NPs is widely applied due to their slower dissolution rate which led to a continuous release of Ag<sup>+</sup> ions from Ag-NPs [35]. In addition, the smaller size of Ag-NPs gives advantages by releasing more Ag<sup>+</sup> ions to the media and inhibits the bacteria growth. The Ag-NPs also are highly diffusive ions into the culture growth medium which are influenced by the oxidation and dilution process from Ag-NPs to Ag<sup>+</sup> ions [36]. In addition, Ag-NPs also easily dissociate into Ag<sup>+</sup> ions after contact with water.

**Figure 14.** The release rate of Ag<sup>+</sup> ions from 6 to 144 h of *C. pentandra*/Ag-NPs.
