Cell viability and cell morphology

The cell viability Kit-8 was employed to quantitatively determine the cytotoxicity of the samples. After 24 h of culture, 10% CCK-8 solution in cell culture medium was added and incubated at 37 ∘C for another 2 h. The OD values at 450 nm were read by a multifunctional full wavelength microplate reader (Infinite 200 pro, Tecan Austria GmbH, Austria). The morphology was observed by FE-SEM.

The live/dead staining assay was performed using a Calcein-AM/PI Double Stain Kit. Cells were seeded in 96-well cell culture plates at a density of 1 × 10⁵ cells per well. Then different samples were added to corresponding wells. After 24 h incubation, cells were washed twice with PBS. Afterward, 100 μL Calcein-AM/PI Double Stain detection working solution was added following the manufacturer's instructions. After 30 min incubated, cells were washed twice with PBS. Finally, the living cells stained with Calcein-AM (λ_ex/λ_em = 490 nm/515 nm) and dead cells stained with PI (λ_ex/λ_em = 535 nm/617 nm) were monitored by a confocal microscope. The numbers of live and dead cells were counted using Image J.