Enhanced oral delivery and bioactivity of EGCG via DNA nanocarriers

Herein we describe epigallocatechin gallate (EGCG), a bioactive green tea extract, loading onto DNA nanostructures [DNA tetrahedron (TDNs) and DNA hydrogel (DH)] for improved bioavailability and biological activity. TDN-EGCG incorporation was confirmed by circular dichroism (CD), UV spectroscopy and gel electrophoresis (PAGE). Degradation kinetics of TDN and DH, with and without EGCG were measured for up to 14 days and quantified by PAGE. TDN-EGCG showed slower degradation than TDN in human saliva, while both nanostructures remained stable in artificial saliva for up to 48 h. DH-EGCG showed improved stability compared to the hydrogel alone. Human gingival fibroblasts exposed to neat-EGCG, TDN-EGCG, TDN, or buffer were analyzed for cell viability, total protein quantification, and cytokines expression levels. Cell viability and total protein levels did not differ from controls. The inhibitory effect of TDN and TDN-EGCG on Streptococcus mutans biofilms was also investigated. TDN-EGCG reduced IL-6, IL-8, and MCP-1 at 6 h and IL-6 and MCP-1 at 24 h timepoints, and inhibited S. mutans biofilm formation after 6 h. Statistical analyses were performed using one-way ANOVA and Tukey's post-hoc test (α = 0.05). These findings highlight TDNs as promising EGCG carriers and support DH-EGCG as a complementary delivery system.