A novel thiolated human-like collage zinc complex as a promising zinc supplement: Physicochemical characteristics and biocompatibility

• Human-like collagen was thiolated for improving its zinc binding ability.
• pH and zinc concentration control the binding amount of zinc to thiolated HLC.
• The physicochemical properties of thiolated HLC–Zn complex were investigated.
• The biocompatibility of thiolated HLC–Zn complex was evaluated.

To improve zinc binding ability to human-like collagen (HLC) and stability of metal complex, HLC was thiolated by mercaptosuccinylation reaction with S-acetylmercaptosuccinic anhydride (S-AMSA) at pH 8.0. One mole of thiolated HLC–Zn (SHLC–Zn) complex possessed 24.3 mol zinc ions when pH was 8.0 and zinc concentration was 15 mM. The physicochemical properties and biocompatibility of thiolated HLC–Zn (SHLC–Zn) complex were investigated by UV–vis, CD, electrophoresis analysis, differential scanning calorimetry (DSC) and cell viability assay, respectively. The results showed that SHLC–Zn complex(1) exhibited higher zinc ions than that of native HLC and still maintained the secondary structure of HLC though interaction occurred between SHLC and zinc ions, (2) increased the apparent molecular weight when compared with native HLC, (3) exhibited greater thermal stability than native HLC, and (4) presented toxicity free for BHK cells. This study suggests that the SHLC–Zn complex is a potential nutrition as well as zinc supplement in the medical application.

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