Medical devices, including catheters, temporary or permanent implants, stents, vascular grafts, anastomotic devices, aneurysm repair devices, embolic devices, and implantable devices (e.g., orthopedic or dental implants) are commonly infected with opportunistic bacteria and other infectious micro-organisms, in some cases necessitating the removal of implantable devices. Such infections can also result in illness, long hospital stays, or even death.
The prevention of biofilm formation and infection on indwelling catheters, orthopedic implants, pacemakers, contact lenses, stents, vascular grafts, embolic devices, aneurysm repair devices and other medical devices is of growing importance. Challenges in medical and medical device coatings include:
• coating adhesion;
• uniform coverage over challenging shapes;
prevention of biofilm formation
The ability of nanocoatings to meet these needs explains why they are under development for medical device applications.
Anti-bacterial: Bacterial infection from medical devices is a major problem and accounts for an increasing number of deaths, as well as high medical costs. MRSA infection is a global problem in healthcare facilities, responsible for up to 50% of hospital infections in the USA and UK. The anti-microbial efficacy of nanocoatings is leading to market growth in this application area. Nanocoatings have been proven to reduce bacterial adhesion and subsequent biofilm formation on medical devices. The nanoparticles are either deposited directly on the device surface, or applied in a polymeric surface coating. The nanoparticle is slowly released from the surface, thereby killing the bacteria present near the surface.
There are significant market opportunities in this sector with the medical catheter market alone projected to reach $22 billion globally by 2012 (ORNL).10% of patients in ICU’s develop catheter related infections, and 40% of these are acquired during their stay. The market will continue to grow as an aging population will drive more hospital stays and infectious agents (bacteria/fungi) continue to evolve quickly and become less susceptible to antibiotic treatments.
Implants: The increased need by an ageing population for spinal, orthopaedic and dental medical devices will also increase demand for medical device coatings with enhanced properties. Also, the increased use of prosthetic devices during the past decades has been accompanied by a constantly increased number of prosthetic device infections.
The biocompatibility of medical devices, stents, and catheters is improved with ultra-thin, ultra smooth coatings that better prevent protein and bacterial attachment. These nanocoatings allow for prevention of bio film, lubrication and cell adhesion for medical implants. Anti-infective nanoscale coating materials improve the efficacy of indwelling and implantable medical devices, while reducing the risk of deadly medical device-related infections. Nanostructured materials can stimulate self-healing cell responses or can increase the biocompatibility of implants.
Stents: Nanomaterials are also being utilized the coating of vascular stents. Nanoporous alumina and hydroxyapatite coatings increase biocompatibility and thus efficient stenting. Coatings currently used in stents have a number of shortcomings including poor healing/thrombosis risk and potential leading to inflammation. Nanoporous drug eluding stents will potentially gain market traction in the coming years due to the aforementioned biocompatibility and ability to deliver therapeutic agents.
Nanocoating technology has already been widely applied in hearing aid coatings (cochlear implants) and is being used by virtually every manufacturer. Producers include Siemens, Phonak, Panasonic, Motorola and Sebotek. They are also being increasingly applied in:
• protective coatings for medical electronics;
• lubricious coatings on medical devices;
• anti-bacterial surfaces for medical catheters;
• anti-bacterial coatings on operating tables, door knobs and door handles in hospitals;
• ultra-hard, biocompatible porous coatings for surgical and orthopedic implants like screws, plates or joint implants.
Nanocoatings companies developing products for the medical devices market include P2i (www.p2i.com), Semblant (www.semblant.com) and GVD Corporation (www.gvdcorp.com) among others. Sandvik’s Bioline 1RK91 products are suture needles with stainless steel nanocoatings (1-10 nm).