Mineralization can help improve the mechanical properties and degradation rates of collagen scaffolds while ensuring good biocompatibility, thereby providing a suitable microenvironment for osteogenic differentiation. Intrafibrillar/extrafibrillar mineralization of collagen is promoted by polymer-induced liquid precursors (PILP). In this study, polyacrylamide (PAM) was introduced to PILP which synergistically mineralized collagen scaffold intrafibrillarly and extrafibrillarly. PAM and polyacrylic acid (PAA) can stabilize the amorphous calcium phosphate (ACP), to form a PILP of PAM and PAA/ACP. As a control, another scaffold material was formed using the conventional mineralization method, that is, soaking collagen in a simulated body fluid. Collagen mineralization was characterized using SEM and TEM. After 7 days of mineralization with PILP, intrafibrillar crystallization of collagen was significantly higher than that in the control group, and the stiffness and modulus of this scaffold material significantly increased. Cellular experiment results indicated that the PILP-mineralized collagen scaffold was biocompatible and promoted the osteogenic differentiation of MC3T3-E1 pre-osteoblasts. Biomimetic mineralization by PILP will assist the fabrication of mineralized collagen scaffold for bone repair applications.
Dental caries is a common oral disease and lacks an effective recovery method. The objective of the study was to investigate the remineralization efficiency of polyelectrolyte‑calcium complexes pre-precursor (PCCP) and polymer-induced liquid-like precursors (PILP) processes on mechanical and biochemical properties of dentin artificial caries lesions (ACLs) evaluated with micro-CT, SEM, TEM, ATR-FTIR, Raman spectra and nanoindentation. The human dentin ACLs were prepared with the depth of 100–120 μm. The intact dentin served as positive control and the dentin ACLs as negative control. The dentin ACLs were either incubated in poly-L-aspartic acid‑calcium suspension (PAsp-Ca, 4 g/L-5.44 M) followed by phosphate solution (0.325 M), and further incubated in artificial saliva serving as PCCP group, or in PAsp-stabilized amorphous calcium phosphate solution serving as PILP group. The micro-CT and SEM findings with EDX indicated that mineral contents of the dentin ACLs were dramatically increased in PCCP group, but, to some degree in PILP group. TEM and nanoindentation results showed that a heavy remineralization of dentin ACLs was obtained via PCCP process with an obvious recovery of mechanical properties while a poor remineralization via PILP process. In conclusion, the PCCP process is a promising strategy for functional remineralization of dentin caries lesions.
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