Bioinertness

Bioinertness is the property of a material to evoke little or no biological response when placed in a living system. In biomaterials science, bioinert materials resist protein adsorption, cell adhesion, inflammation, and bonding with surrounding tissue, yielding a stable, passive interface. The goal is to minimize adverse reactions and prevent unintended tissue integration, corrosion, or degradation at the implant surface.

Bioinertness is achieved through stable chemical composition and surface properties that discourage biological fouling. Design strategies include creating surfaces with low protein adsorption, using hydrophilic or nonfouling coatings, and employing materials with robust, inert oxide layers. Nonfouling polymers such as polyethylene glycol or phospholipid-like coatings are examples used to reduce adhesion of proteins and cells.

Commonly cited bioinert materials include polytetrafluoroethylene (PTFE), a number of ceramics such as certain alumina or zirconia, and some noble metals and glasses that resist chemical interaction in vivo. It is important to note that many implants aim for osseointegration or tissue bonding, which is the opposite of bioinert behavior; in those cases a bioactive material may be preferred.

Bioinertness sits within the broader concept of biocompatibility. A material can be biocompatible while not being bioinert if it forms bonds with tissue, and conversely a bioinert surface may still require protection against wear, corrosion, or mechanical failure. The concept arose from early biomaterials research in which researchers categorized materials by their tissue response: bioinert, bioactive, and biodegradable.

See also: biomaterials, biocompatibility, osseointegration, bioactivity.