Release behavior and signaling effect of vitamin D3 in layered double hydroxides-hydroxyapatite/gelatin bone tissue engineering scaffold: An in vitro evaluation

Incorporating the controlled release of vitamin D3 (VD3) into biodegradable porous scaffolds is a new approach to equipping multifunctional therapeutics for osteoporosis. The current investigation involves the encapsulation of VD3 into gelatin through the one-step desolvation method. The layered double hydroxides-hydroxyapatite nanocomposite (LDH-HAp) and pure LDH were combined with the gelatin-VD3 complex to reinforce the porous biodegradable structure and enhance the biological response. Afterwards, glutaraldehyde was used to form crosslinks within the gelatin chains. The encapsulation efficiency and loading capacity showed approximately 40% and 50% reduction after crosslinking, respectively. The particle size, zeta potential, contact angle, Young's modulus and porosity were measured to find the effect of VD3 on the scaffolds' physiochemical properties. To explore the bioactivity and degradation behavior, the scaffolds were immersed in simulated body fluid. The VD3 release kinetics followed the Korsmeyer-Peppas model and non-Fickian release pattern. The greater osteblastic expression was observed in VD3-containing scaffolds due to the higher alkaline phosphatase activity which was excited more by HAp (P<0.05). Alizarin red staining illustrated that VD3 induced more calcium deposition, which indicates the signaling role of VD3 on osteoconductivity and biomineralization. The findings provide new insights on the VD3 encapsulation within hydrophilic matrices to protect VD3 and enable the signaling ability for bone tissue engineering scaffolds, which could improve the bone healing efficiency. (C) 2017 Elsevier B.V. All rights reserved.