Sol-gel derived silica-based 58S bioactive glass as a carrier for Andrographis paniculata extract in antibacterial...

Dental caries and associated oral infections require biomaterials that promote remineralization while controlling bacterial growth and maintaining cytocompatibility. In this study, a sol-gel-derived silica-based 58S bioactive glass was investigated as a carrier for Andrographis paniculata (AP) extract (AP@58S-2) for antibacterial dental applications. Spherical 58S particles were synthesized via a two-step sol-gel route, yielding an amorphous glass with a high specific surface area of 786.3 m² g^-1 and mesopores distributed in the 1.49-2.14 nm range, as confirmed by SEM, TEM, XRD, and nitrogen adsorption analyses. Compared with glass prepared by a one-step method, the two-step 58S exhibited a more uniform morphology and moderate pH variation during immersion, which is favorable for cellular compatibility. The mesoporous structure enabled efficient AP extract loading (∼65%, corresponding to ∼10.6 µg extract per mg glass) and supported sustained release of andrographolide, reaching approximately 70% cumulative release within 24 h under simulated physiological conditions. In vitro cytocompatibility assays demonstrated that AP@58S-2 maintained hMSC viability above 90% across the tested extract concentrations. Antibacterial evaluation against Streptococcus mutans revealed enhanced efficacy for AP@58S-2 compared with the unloaded bioactive glass, with a minimum inhibitory concentration of 1.5 mg mL^-1 and bactericidal behavior indicated by an MBC/MIC ratio of 1.33, together with a time-dependent reduction in biofilm viability. AP@58S-2 demonstrated potent antioxidant activity through effective DPPH and ABTS radical scavenging and significantly reduced nitric oxide generation in LPS-stimulated RAW 264.7 cells. These results indicate that morphology-controlled 58S bioactive glass can function as an effective carrier for plant-derived bioactive compounds, providing combined mineralization-related bioactivity, antibacterial effects, and antioxidant functionality. This integrated approach is relevant for dental applications where infection control and oxidative stress management are required alongside tissue regeneration.