Figure 4.

Cytotoxicity of materials tested for cell viability by MTT assay in MDCK cells.

Notes: As a function of nanoparticle and modified nanoparticle concentrations (A). As a function of prodrug and nanoformulation concentrations equal to pure prodrugs used alone (B). SH/QR mix2 (pure prodrug mixture) and MSNs-NH₂-SH-QR2 are the same materials as SH/QR mix1 and MSNs-NH₂-SH-QR1 but twice the amount – see Table 1. Antiviral activity against H5N1 virus (C). The safe concentration (equivalent to 75 µg/mL of free compound or found in nanoformulations) was used for all materials. The safe concentration used for unmodified and modified nanoparticles was 50 µg/mL. Data are presented as mean ± SD. *Means significant differences at p <0.05. The concentration for MSNs and MSNs-NH₂ was directly made of prepared powder of both nanoparticles. The concentration used in nanoformulations of MSNs-NH₂-SH, MSNs-NH₂-QR, MSNs-NH₂-SH-QR, and MSNs-NH₂-SH-QR2 was calculated based on the prodrug loaded into nanoparticles as an equivalent to free prodrugs (SH, QR, SH/QR mix1, and SH/QR mix). The free prodrug concentration was normally made from the powder of pure prodrugs without any calculation.

Abbreviations: MTT, cell proliferation assay; MDCK, Madin-Darby Canine Kidney cells; MSNs, mesoporous silica nanoparticles; MSNs-NH₂, MSNs modified amino groups; MSNs-NH₂-SH, MSNs-NH₂ loaded SH; MSNs-NH₂-QR, MSNs-NH₂ loaded QR; MSNs-NH₂-SH-QR1, MSNs-NH₂ loaded SH and QR; MSNs-NH₂-SH-QR2 was used in twice amount; SH/QR mix.1, mixture of SH and QR; SH/QR mix.2, mixture of SH and QR used in twice amount; SH pure, shikimic acid; QR pure, quercetin; SD, standard deviation.