Ceramics and Nanoceramics in Biomedical Applications

Abstract

A ceramic is an inorganic nonmetallic solid made up of either metal or nonmetal compounds; they are hard, corrosion-resistant, and brittle. Ceramics are also known as bioceramics, which include macro- and nanomaterials mainly used for bone, dental, and medical applications. The more restrictive term porcelain refers to a specific compositional range of ceramic materials originally made by mixing kaolin (hydrated aluminosilicate), quartz (silica), and feldspars (potassium and sodium aluminosilicates) and firing at a high temperature. Nanostructured ceramics are being considered for major use in orthopedic, dental, and other medical applications. Bioceramics are a class of advanced ceramics that are defined as ceramic products or components employed in medical and dental applications, mainly as implants and replacements. Bioceramics are materials which include alumina, zirconia, bioactive glass, glass ceramics, hydroxyapatite, and resorbable calcium phosphates, among others. They have a similarity to hydroxyapatite, an intrinsic osteoconductive activity, and have an ability to induce regenerative responses in the human body. The term nanoceramics refers to materials fabricated from ultrafine particles, less than 100 nm in diameter, and is classified as inorganic, heat-resistant, and nonmetallic solids. Nanomaterials are defined as those materials whose length scale lies within the nanometric range, i.e., from 1 to 100 nanometers. Within this length scale, the properties of matter are considerably different from the individual atoms, molecules, and bulk materials. The physical, chemical, electrical, and optical properties of these materials are size and shape dependent, and they often exhibit important differences from the bulk properties. These unique properties are related to the large number of surface or interface atoms. Nanostructured ceramic materials have good refractory properties, good chemical resistance, good mechanical resistance, and hardness both at normal and high temperatures; they are especially amenable to sintering and reactions with different oxides. The interest has been stimulated by the large variety of applications in industries such as fabrication of dense ceramics, sensors, batteries, capacitors, corrosion-resistant coatings, thermal barrier coatings, solid electrolytes for fuel cells, catalysts, cosmetics, health, automotive, bioengineering, optoelectronics, computers, electronics, etc. Currently, the importance of nanomaterials in the field of luminescence has increased, especially, as they exhibit enhanced optical, electronic, and structural properties.