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

Abstract

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.