Cell counting kit

Hepatocellular carcinoma cell lines (HCC, including HepG2 and Huh7) and human normal cells (HL-7702) were available from the Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences (CAS). HepG2 and Huh7 cells were cultured in DMEM (Biosharp; Biosharp Life Sciences) with 10% FBS (Biosharp; Biosharp Life Sciences) at 37°C with 5% CO₂.
Cell viability was determined using a Cell Counting Kit. HepG2 cells (2 × 10³/well), Huh7 cells (2 × 10³/well), and HL-7702 (2 × 10³/well) were seeded into 96-well plates. The cells were cultured with the NPs of compounds 1 and 2 for 24 h, respectively. Cytotoxicity was evaluated using the Cell Counting Kit-8 (CCK-8, Abbkine Scientific). CCK-8 was added to the medium and incubated with the cells for 2 h. Then, the absorbance was measured on a microplate reader. The cell viability was calculated as follows: $\text{Relative}\text{cell}\text{viability}(\%)=\left(A_{treatment}/A_{control}\right)\times 100\%$
where A_treatment = mean absorbance of the medium from cells incubated with NPs containing complex 1 or 2 and A_control = mean absorbance of the medium incubated without NPs of non-treated cells. The half-maximal inhibitory concentration (IC₅₀) was calculated using SPSS 25.0 software.
The MTT assay was repeated three times.

The cell viability assay was similar to that used in our previously published paper [28 (link)]. Briefly, HL-60 and K562 cells that were seeded into 96-well cell culture plates at a density of 1 × 10⁵ cells/well were treated with PBS buffer, various concentrations of free Ara-C or various concentrations of Ara-C@HFn with the equivalent amount of Ara-C for 48 h. After incubating for 2 h, the absorbance value at 450 nm in each well was measured by the Infinite M200 microplate spectrophotometer (TECAN, Switzerland), and cell viability was assessed by using the CCK-8 assay (Cell Counting Kit, Biosharp, n = 4).