Supramolecular Gels Incorporating Cordyline terminalis Leaf Extract as a Polyphenol Release Scaffold for Biomedical Applications

Cordyline terminalis leaf extract (aqCT) possesses abundant polyphenols and other bioactive compounds, which are encapsulated in gelatin-polyethylene glycol-tyramine (GPT)/alpha-cyclodextrin (alpha-CD) gels to form the additional functional materials for biomedical applications. In this study, the gel compositions are optimized, and the GPT/alpha-CD ratios equal to or less than one half for solidification are found. The gelation time varies from 40.7 min to 5.0 h depending on the increase in GPT/alpha-CD ratios and aqCT amount. The aqCT extract disturbs the hydrogen bonding and host-guest inclusion of GPT/alpha-CD gel networks, postponing the gelation. Scanning electron microscope observation shows that all gels with or without aqCT possess a microarchitecture and porosity. GPT/alpha-CD/aqCT gels could release polyphenols from 110 to 350 nmol/mL at the first hour and sustainably from 5.5 to 20.2 nmol/mL for the following hours, which is controlled by feeding the aqCT amount and gel properties. GPT/alpha-CD/aqCT gels achieved significant antioxidant activity through a 100% scavenging DPPH radical. In addition, all gels are non-cytotoxic with a cell viability more than 85%. Especially, the GPT3.75 alpha-CD10.5aqCT gels with aqCT amount of 3.1-12.5 mg/mL immensely enhanced the cell proliferation of GPT3.75 alpha-CD10.5 gel without extract. These results suggest that the inherent bioactivities of aqCT endowed the resulting GPT/alpha-CD/aqCT gels with effective antioxidant and high biocompatibility, and natural polyphenols sustainably release a unique platform for a drug delivery system or other biomedical applications.

Automated summary

The study involved encapsulating bioactive compounds from Cordyline terminalis leaf extract in gelatin-polyethylene glycol-tyramine (GPT) / alpha-cyclodextrin (α-CD) gels to create materials for biomedical applications with antioxidant properties and high biocompatibility. The addition of the extract delayed gelation time, but sustained release of polyphenols was achieved by adjusting the aqCT amount and gel properties.