Figure 2. Biofilm formation process. Conditioning film is formed upon protein adsorption. Bacteria adhere and proliferate on the surface to produce extracellular polymeric substances (EPS).
There is a high demand of medical device and implants especially for blood contacting devices as well as orthopedic and dental implants. Here, we focused on how surface engineering techniques on blood-contacting devices and hard tissue implants improve their biocontact performance. Current surface modifications to optimize the antithrombogenicity of biomaterials mainly include physiochemical treatments such as surface patterning, plasma treatment and surface coating especially with heparin, and biofunctionalization that relies on incorporating bioactive agents. Surface engineering of biomaterials for hard tissue applications typically focusing on promoting implant-tissue integration and enhancing the corrosion and wear resistance.
Stem cell-based strategies offers a great potential to tissue engineering and regenerative medicine owing to their self-renewal ability and multipotency to differentiate into multiple linages. Normally, stem cells are isolated from their original microenvironment and processed through in vitro expansion prior to seeding on scaffolds for engineered tissue production. Notably, the substrate in which the stem cells are cultured is required to encourage their proliferation and expansion while maintain their multipotency. Subsequently, the large population of stem cells is favored for producing engineered tissue through desired differentiation. Therefore, deliberate selection of the biomaterials and proper surface modifications are critical to stem cells regulation.
Commonly used surface engineering methods are summarized in Table 1. Physicochemical methods alters surface characteristics by physical texturing and/or chemical reactions including acid etching/oxidation, grafting of functional groups, surface coating by deposition and ionizing irradiation treatments and surface patterning by lithography[1]. Biological methods are mainly based on biomolecules immobilization either by physical adsorption or covalent bonding. Not all surface engineering techniques are applicable and favorable to all biocontact scenarios. Therefore, this review will be application targeted that recent advances in surface modifications to address associated problems in optimizing different interactions between biomaterial and living matter are focused.
Table 1. Summary of common surface engineering techniques used for biomaterials.