Surface Coatings for Biomedical Technologies

Medical devices are routinely used in an invasive manner for a gamut of clinical applications. Invasive devices include endoscopy probes for diagnostic imaging that stay in the body for a short period of time; temporarily implanted devices, such as catheter tubes; and indwelling devices, such as orthopedic implants, cardiac pacemakers and stents. A concern that is common to all device classes is the risk of infection. There is no clinical consensus on the infection rate from implants. Clinical research groups (Kurtz et al and Urban et al) estimate between a 1 and 16% chance of infection from orthopedic implants, a class of devices that has a reliable registry to track infections. According to these studies, the financial burden from orthopedic implant-associated infections in the United States will be as high as $1.6 billion by 2020. This is, of course, just a small piece of the pie; the impact of all device classes will be an order of magnitude higher.

Infection risk is not limited to invasive medical devices. The hospital environment is an acknowledged incubator of microorganisms. One of the biggest disease burdens of the world is healthcare-acquired infections (HAIs), or nosocomial infections. According to the U.S. Centers for Disease Control and Prevention (CDC), on any given day one in 25 patients contracts at least one HAI, and every year more than 700,000 HAIs are diagnosed in acute care hospitals in the country.  Promisingly, the CDC has designated HAIs as a Winnable Battle, indicating that much progress has been made in the area and that this will be a prime focus area of the healthcare stakeholder network. An important step in this direction will be to either impart medical devices with antimicrobial coatings or to suitably modify their surfaces so that they do not support the formation of biofilms, or structured bacterial communities. A Frost & Sullivan industry research study published in May 2017 reported that global revenue in the antimicrobial coating materials market stood at $700 million in 2016, and is poised to reach $1.1 billion by 2021. Exhibits 1 and 2 show the 2016 global revenue shares for polymeric and metallic antimicrobial coatings by application.

In this article, Frost & Sullivan sheds light on innovative antimicrobial coating and modification techniques for biomedical devices.

Nanotechnology and Bioengineering Division, Institute of Technology Sligo (Sligo, Ireland)

A research team led by Suresh Pillai at the institute’s Nanotechnology and Bioengineering Division has developed a nanotechnology-based coating using titanium dioxide co-doped with fluorine and copper. The solution is baked on a surface such as glass; when light is shone on it, a series of reactions ensue that make the surface resistant to the proliferation of microorganisms such as E. coli, trichophyton rubrum and Methicillin-resistant Staphylococcus aureus. The coating is transparent and hydrophilic, making it conducive to be sprayed onto surfaces of medical devices, hospital supplies and even wall tiles and door handles. The technology is being commercialized by Dublin-based Kastus.

Innovative Surface Technologies, Inc. (ISurTec; St. Paul, Minn.)

ISurTec, a coating formulation company, has developed a method to immobilize biocompatible and biodegradable particles on the surface of medical devices so as to impart antimicrobial properties. This proprietary coating process also gives the surface a tendency to repel water, or become “super-hydrophobic.” The combination of super-hydrophobicity and antimicrobial agents is effective in minimizing bacterial adhesion on catheter walls, drug delivery systems and ventilation tubes. ISurTec partners with device companies to co-create new coatings and surface modifications to cater to a diverse range of industry requirements.

AST Products, Inc. (Billerica, Mass.)

AST Products is a surface technology company that offers a line of patented coating technologies for the medical device and specialty chemicals industries. One of AST’s novel offerings is RepelaCOAT, a polymeric coating loaded with silver salts and antibiotics that act as strong antibacterial agents. RepelaCOAT has been devised to minimize loss of antibacterial agents in the body due to wash-off. In the presence of calcium and sodium ions in bodily fluids, the polymer absorbs water, and releases antibiotics only under these conditions. An important feature of RepelaCOAT is that it presents a consistent drug release profile specific to the local area to minimize the risk of targeting healthy tissues and to deliver a safe coating system with no residual solvents.

School of Optometry and Vision Science, University of New South Wales (Australia)

It is estimated that more than 140 million people use contact lenses worldwide. While lens use is largely safe, there is a minor risk of infection—between 4 and 20 cases per 10,000 users. A research team from the University of New South Wales has used the peptide melimine to coat the inner surface of contact lenses. Peptides are biocompatible biomolecules with an inherent ability to fight microorganisms. The team observed the peptide to be heat-stable and to not alter the physical or optical properties of the lenses. The coating has been studied on animals and for short-period use on human volunteers. Melimine coating is understood to provide protection against ocular pathogens including bacteria, fungi and Acanthamoeba.

The Road Ahead

The need for powerful antimicrobial materials is growing, not least because microorganisms’ resistance to antibiotics continues to strengthen. The emergence of superbugs has underscored the importance of constantly improving the defense against (or attack of) an enemy that “learns” from its defeat. Frost & Sullivan senses a huge opportunity for multidisciplinary research and collaboration in this challenge. Already, large medical device corporations and material science companies are partnering with academic research groups to develop innovative antimicrobial coatings.

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