Biomaterials are generally selected for their chemical inertness and low surface energies. Nevertheless, these properties can also result in difficulties in effectively applying functional coatings and enabling appropriate interactions with other surfaces.
This article details the advantages of plasma treating biomaterials in order to offer additional improvements to their functionality, as well as offering example applications and plasma treatment processing recommendations.
Advantages of Plasma Treatment of Biomaterials
Plasma treatment alters the surface wetting properties, which, in the end, can augment the functionality and biocompatibility of biomaterial surfaces. Plasma presents oxygen-containing functional groups to improve surface hydrophilicity of biomaterials, without an impact on their main material properties.
This improves the bonding properties of later coatings or absorption of other functional groups. Additionally, oxygen plasma has the extra advantage of both cleaning and sterilizing biomaterial surfaces in laboratory research environments at once.
Plasma treatment can be used on a broad range of materials, as well as complex surface geometries. Listed below are some examples of biomedical applications and samples that have been treated using plasma instruments:
- Treat fibrous polymer scaffolds to improve surface hydrophilicity and increase cell adhesion, coverage, and proliferation for tissue engineering
- Enable bonding of polydimethylsiloxane (PDMS) microfluidic devices fabricated for cell culturing
- Activate sapphire surface to enhance adhesion of heparin coating and increase biocompatibility as an implant material
- Adapt surface chemistry of PDMS to stimulate adsorption of polyethylene glycol (PEG) as an anti-biofouling coating
- Treat ultra-high molecular weight polyethylene (UHMWPE) to improve surface hydrophilicity and stimulate protein adsorption, which can act as a lubricant and lessen friction in artificial joints
- Clean and activate microelectrode arrays (MEAs) for the fabrication of biosensors
- Sterilize titanium implant materials, stainless steel, and fibrous polymer scaffolds
Air or oxygen (O2) gas is generally used for plasma cleaning. An air or O2 plasma eliminates biological contaminants through chemical reaction with highly reactive oxygen radicals and ablation by energetic oxygen ions. The plasma also encourages hydroxylation (OH groups) on the surface, making the surface more hydrophilic and improving surface wettability
As an alternative, an argon plasma may be favored for cleaning in order to minimize additional oxidation of surfaces (e.g. metals). Argon plasma does not react with the surface directly, but instead, cleans through ion bombardment and physical ablation of contaminants off the surface.
In some instances, a compound of Ar/O2 has been used for plasma sterilization, as it was discovered that the introduction of oxygen rendered the process more effective in destroying microorganisms than Ar plasma alone .
The process parameters for treating biomaterials diverge greatly as plasma treatment can be applied to multiple, distinct biomedical applications and materials.
References and Further Reading
 Moisan, Michel, Jean Barbeau, Marie-Charlotte Crevier, Jacques Pelletier, Nicolas Philip, and Bachir Saoudi. "Plasma sterilization. Methods and mechanisms." Pure Appl. Chem. (2002) 74(3): 349-358.
This information has been sourced, reviewed and adapted from materials provided by Harrick Plasma.
For more information on this source, please visit Harrick Plasma.