The internal environment of the body is often modeled to be an aqueous environment at 37 °C at pH 7.3 with plenty of dissolved oxygen, electrolytes, proteins, and cells. When exposed to oxygen for an extended period of time, many metals may become oxidized and increase their surface oxidation state by losing electrons. This new cationic state leaves the surface with a net positive charge, and a higher affinity for negatively charged protein side groups. Within the vast diversity of metals and metal alloys, many are susceptible to corrosion when implanted in the body. Elements that are more electronegative are corroded faster when exposed to an electrolyte-rich aqueous environment such as the human body. Both oxidation and corrosion will lower the free energy, thus affecting protein adsorption as seen in Eq. 1.
