UV irradiation enhances the bonding strength between citric acid-crosslinked gelatin and stainless steel

The effect of ultraviolet ray (UV) irradiation on the bonding strength between low carbon stainless steel 316 (SUS316L) and trisuccinimidyl citrate (TSC)-crosslinked alkali-treated gelatin (AlGelatin–TSC) was investigated. The UV irradiation effectively generated hydroxyl groups on the surface of SUS316L. The bonding strength between AlGelatin–TSC and SUS316L before UV irradiation was 0.345 ± 0.007 MPa, and upon UV irradiation it increased to 0.750 ± 0.069 MPa. In order to explain this enhanced bonding strength, the surface of SUS316L was examined using its water contact angle and X-ray photoelectron spectroscopy. Furthermore, the N 1s peaks derived from the TSC succinimidyl group were assigned to the surface of SUS316L after the immobilization of the TSC. This indicates that ester bond formation between the TSC active esters and the SUS316L hydroxyl groups contributed to the enhanced bonding strength. Therefore, UV irradiation and subsequent TSC immobilization is a simple way to functionalize biometal surfaces with various structures. This has practical applications for medical devices such as drug-eluting stents, dental implants, and metallic artificial bone.

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► We evaluated the effect of ultraviolet ray irradiation on the bonding strength between SUS316L and trisuccinimidyl citrate crosslinked gelatin.
► Surface analyses showed that hydroxyl groups were generated on the SUS316L surface, formed ester bonds with the active ester groups of trisuccinimidyl citrate.
► These covalent bonds contributed the bonding strength between SUS316L and trisuccinimidyl citrate crosslinked gelatin.