Vitamin D3 mediated peptides-calcium chelate self-assembly: Fabrication, stability and improvement on cellular calcium transport

A self-assembled peptides-calcium-Vitamin D 3 ternary delivery system (CSPH-Ca-VD 3 ) was prepared to investigate the promotion of cellular calcium transport. The constructed CSPH-Ca-VD 3 nanocomplex exhibited a spherical structure with a size of 135.2 ± 10.2 nm. Based on the thermodynamic calculation of fluorescent spectra, hydrophobic interaction was shown as the major driving force for this nanocomplex structure. CSPH-Ca-VD 3 nanocomplex possessed excellent stability during simulated gastrointestinal digestion, contributing to the prevention of acid degradation of VD 3 and the enhancement of calcium solubility. Furthermore, the calcium transport efficiency in the form of CSPH-Ca-VD 3 (4 mg/mL) across a Caco-2 cells monolayer was significantly increased 2.3-fold compared to that of free Ca 2+ , mainly attributed to the upregulation in the presence of CSPH-Ca-VD 3 of TRPV6, calbindin D9k and PMCA1b expression in Caco-2 cells. The present study provided a basis for developing a novel delivery system of peptides-calcium chelate with the dual effects of VD 3 protection and calcium uptake promotion.