2.5.1. Caco-2 cell culture and calcium uptake assay

Caco-2 cells were maintained in DMEM supplemented with 20% (V/V) FBS, 1% non-essential amino acids, and 1% penicillin/streptomycin at 37 °C with 5% CO_2. After reaching 90% confluence, the cells were seeded in 12-well culture dishes (Corning Costar, New York, USA). After incubation for 48 h, cells were treated with CSPHs-Ca and XOS-CSPHs-Ca-TG (2–8 mg/mL) for 2 h, respectively. Subsequently, 100 μL Fluo-3AM (5 μM) was added to each well and incubated at 37 °C for 1 h. Then, 1 mL of HBSS was added to each well and incubated for 30 min. After detached and resuspending with HBSS, the intracellular calcium concentration [Ca²⁺]_i of the cells was detected by flow cytometry (BD AccuriC6 Plus, BD Bioscience, New Jersey, USA).