The role of temperature in forming sol–gel biocomposites containing polydopamine

Abstract

To further improve the physical strength and biomedical applicability of bioceramicsbuilt on hydroxyapatite-gelatin (HAp-Gel) and siloxane sol-gel reactions, we incorporated mussel adhesive inspired polydopamine (PD) into our original composite based on HAp-Gel cross-linked with siloxane. Surprisingly, with the addition of PD, we observed that the processing conditions and temperatures play an important role in the structure and performance of these materials. A systematic study to investigate this temperature dependence behavior discloses that the rate of crosslinking of silane during the sol-gel process is significantly influenced by the temperature, whereas the polymerization of the dopamine only shows minor temperature dependence. With this discovery, we report an innovative thermal process for the design and application of these biocomposites.

Polydopamine Surface Chemistry: A Decade of Discovery

“…As an example of PD applications in composites, the mechanical properties of bioceramics composed of hydroxyapatite and gelatin modified with silane (HAp-Gemosil) was improved by incorporation of PD. 248 The compressive strength of PD-incorporated HAp-Gemosil (HAp-Gemosilamine) at is approximately 100 MPa, higher than that of HAp-Gemosil (∼80 MPa). Several other recent reports have been published showing the ability of PD to enhance mechanical properties of composites.…”

Nanocrystalline Cellulose-Derived Doped Carbonaceous Material for Rapid Mineralization of Nitrophenols under Visible Light

“…30 Therefore, when TiO 2 and NCs were mixed in the presence of dopamine under alkaline condition, polydopamine forms in situ and it helps to immobilize TiO 2 on the NCs. 31 Furthermore, when mixed together TiO 2 alone is capable of forming weak co-ordinate covalent bond with the hydroxyl (−OH) groups present in NCs. However, in the presence of polydopamine, TiO 2 is immobilized strongly to the surfaces of NCs.…”

Dramatic Improvement of the Mechanical Strength of Silane-Modified Hydroxyapatite–Gelatin Composites via Processing with Cosolvent

“…The method for making the composites was adapted from the previous report. 12 HAp–Gel (300 mg) and 200 mg of Ca(OH) 2 with CHX powder were transferred into a mortar and ground into fine powder. Then, the powdered mixture was spread on a glass sheet, which was placed on a cold stage to maintain a depressed temperature of—20 °C.…”

“…Additionally, cylinder-shaped samples with a 1:2 ratio of diameter (3.8 mm) to length (7.6 mm) were made according to our previous report with the same composition as described above. 12 To prepare a pure enTMOS network without HAp–Gel and Ca(OH) 2 CHX, APS was directly added to the premixed enTMOS solution. After gelation, the same drying process was applied as described above.…”

“…However, the compressive strength improvement was still limited, only from 80 to 100 MPa, which was caused by the lack of long-range interactions among different components in the composites. 12 …”