Covalent Bonds: Strong and Durable
There are multiple types of chemical bonds that may attach molecules together or to a surface:
Hydrogen and Van der Waals bonds are the most common and weakest forms of chemical bonds. These are commonly seen in antibiotics that are adsorbed to a material surface or antibiotic bone cement. These types of bonds are easily broken and therefore have limited functional lifespan.
Product Examples: Adsorbed antibiotic, Antibiotic cement
Characteristics: Weak, transient, easily broken
Ionic bonds are represented by many drug-eluting stents or hydroxyapatite-coated surfaces. These are strong bonds, but can be unstable under certain circumstances, including in bodily fluids. These types of bonds are often used in anticipation of the molecule coming off the material surface.
Product Examples: Ag++, HA coatings, Drug-eluting stents
Characteristics: Strong, not stable in all solvents
Covalent bonds are among the strongest and most durable of all types of chemical bonds. They are exceptionally stable when attached to surfaces in a variety of very harsh conditions and environments. MST focuses on covalent bonding strategies for its multiple molecular surface modification technologies, providing long-lasting function with little to no threat of harm to the surrounding tissue or local environment.
Product Examples: MST Anodization
Characteristics: Strong, stable (nearly permanent), more difficult to break
Diverse Bonding Strategies
The creation of these surfaces and covalent bonding requires the addition of energy to drive chemistry at the surface. We have pioneered the use of multiple strategies that are tailored to the specific types of materials and applications. Such bonding strategies include:
Electrical energy is used to drive chemical reactions resulting in stable robust modified surfaces. This is analogous to and often nearly identical to typical anodization processes. Such processes may be carried out in a common aqueous (water) or organic (methanol) environment depending on the exact chemical reactions required. This is highly cost effective for conductive surfaces and familiar to nearly all industrial manufacturers.
Depending on size and material properties, adding energy by forms of light may be more effective and economical. We most commonly employ ultraviolet light to drive reactions at the material surface for this bonding strategy.
Using heat to add energy to drive chemical reactions is the oldest and simplest solution. Most commonly, MST may employ indirect heating to material surfaces that provides for a very uniform energy density and delivers consistent, predictable results.