Freeze-thawed hydrogel loaded by Piper crocatum extract with in-vitro antibacterial and release tests

Indonesian red betel (Piper crocatum) has been used traditionally to cure wounds and to prevent diseases as well as an antiseptic, while the leaves were also reported to inhibit the growth of bacteria. On the other hand, polyvinyl alcohol (PVA) is a suitable biomaterial with a wide range of applications after being transformed into hydrogels. This paper reports on the encapsulation of P. crocatum extract in PVA hydrogel synthesized by the freeze-thaw method with varying compositions and its characterizations. The internal morphology of the composite hydrogels did show some phase separation between the liquid and solid phases, while the analysis of the Fourier-transform infrared spectra confirmed that the P. crocatum extract was successfully encapsulated in the hydrogels. The hydrogels were amorphous due to the scattering of the liquid trapped within the pores. The extract was stable within the range of the room to body temperature since no significant mass decomposition of the extract was observed. The compressive modulus and the fracture stress of the composite hydrogel decreased as the fraction of extract increased due to the unfrozen ethanol fraction during the freeze-thaw process. The composite hydrogels loaded by P. crocatum extract possessed antibacterial activity against Staphylococcus aureus (gram-positive) and Pseudomonas aeruginosa (gram-negative). The release of extract from the hydrogels was immediate release following the pseudo-fickian diffusion for most of the composite hydrogels. This report thus suggests that the composite hydrogels are potential antibacterial products and can be applied for a biomedical device that requires antibacterial activity.