Surface Modification of Bone Implanted Materials by Layer-by-Layer Self Assembly Technique

Abstract

In recent years, surface modifications for dental implants have evolved rapidly, particularly for enhanced osseointegration and bone formation around implants. In this study, a powerful layer-by-layer self-assembly (LbL) technique was employed to fabricate thin film through precise control of the chemical composition and film morphology on a nanoscale level. Potent biomaterials were used for the multilayer coating, including silk fibroin (SF), type I collagen (Col), and poly(diallydimethylammonium chloride) (PDDA), which each impart the surface with a combination of biomechanical, physiochemical, and hydrophilic wetting properties. These materials were assembled sequentially via electrostatic interaction in an aqueous solution phase to produce a [PDDA/SF/PDDA/Col], thin film with different n quad- layers: n = 0 (control), 10, 20, 30, 40, and 50. The multilayer formation, topography, morphology, and the surface characteristics of the films were tested and analyzed using quartz crystal microbalance, atomic force microscopy, scanning electron microscopy, and wettability, respectively. The molecular organization of the films was characterized by Fourier transform infrared and Raman spectroscopy. Meanwhile, their biological performance was evaluated using osteoblast cell proliferation, alkaline phosphatase (ALP) activity, and total protein absorption. The thickness of multilayer film can be changed by increasing the number of quad-layers adsorbed with an increment of 7 nm. It was also found that the surface topography was affected by the number of quad-layers as the root mean square roughness of the film increased as a function of n in a range of tens of nanometers, which is beneficial for initial cell adhesion. The multilayer films demonstrated the mobility of amide I, II, III, and molecular skeletal vibration. The films exhibited rough surfaces, hydrophilicity, and were able to enhance cell proliferation, ALP activity, and total protein absorption. Preliminary results appear the optimum of the number of quad-layers between 40 and 50. The results indicate that self- assembledLbL films are promising for use as a nucleating surface for osseointegration in the design of coated dental implant materials and could serve as the foundation for further clinical applications.