Coating Spray Technique Offers Medical Possibilities

TUESDAY, SEPTEMBER 5, 2023


Scientists from Rutgers University have reportedly devised a method for creating coatings of biologically active materials using the industrial spray-coating process electrospray deposition.

The findings could potentially lead into a new era of transdermal medication, including shot-free vaccinations, according to the team. The research was recently published in the journal Nature Communications.

About the Method

For the research, the scientists reportedly developed a way to better control the target region within a spray zone, as well as the electrical properties of microscopic particles that are being deposited. Combined, these two features mean that more of the spray is likely to hit its microscopic target.

In electrospray deposition, manufacturers apply a high voltage to a flowing liquid, such as a biopharmaceutical, converting it into fine particles. Each of those droplets evaporates as it travels to a target area, depositing a solid precipitate from the original solution.

“While many people think of electrospray deposition as an efficient method, applying it normally does not work for targets that are smaller than the spray, such as the microneedle arrays in transdermal patches,” said Jonathan Singer, an associate professor in the Department of Mechanical and Aerospace Engineering in the Rutgers School of Engineering and an author on the study.

“Present methods only achieve about 40% efficiency. However, through advanced engineering techniques we’ve developed, we can achieve efficiencies statistically indistinguishable from 100%.”

According to the university, coatings are becoming increasingly critical for a variety of medical applications, used on medical devices such as stents, defibrillators and pacemakers. Additionally, they are beginning to be used more frequently in new products employing biologicals, such as transdermal patches.

Rutgers notes that advanced biological or “bioactive” materials, like drugs and vaccine, can be costly to produce, especially if any of the material is wasted. This can consequently limit whether a patient can receive a given treatment.

“We were looking to evaluate if electrospray deposition, which is a well-established method for analytical chemistry, could be made into an efficient approach to create biomedically active coatings,” Singer said.

Higher efficiencies could be the key to making electrospray deposition more appealing for the manufacture of medical devices using bioactive materials, researchers said.

“Being able to deposit with 100% efficiency means none of the material would be wasted, allowing devices or vaccines to be coated in this way,” said Sarah Park, a doctoral student in the Department of Materials Science and Engineering who is first author on the paper.

“We anticipate that future work will expand the range of compatible materials and the material delivery rate of this high efficiency approach.”

Additionally, researchers say that unlike other manufacturing coating techniques like dip coating, the electrospray deposition technique is characterized as “far field,” meaning that it doesn’t need highly accurate positioning of the spray source. As a result, the equipment necessary to employ the technique for mass manufacturing would be more affordable and easier to design.

Other Rutgers scientists on the study included professors Jerry Shan and Hao Lin, former doctoral students Lin Lei (now at Chongqing Jiaotong University) and Emran Lallow (now at GeneOne Life Science, Inc.), and former undergraduate student Darrel D’Souza, all of the Department of Mechanical and Aerospace Engineering; and professors David Shreiber and Jeffrey Zahn, doctoral student Maria Atzampou, and former doctoral student Emily DiMartini, all of the Department of Biomedical Engineering.

The work was supported by GeneOne Life Science, Inc.

Other Medical Coatings Research

At the end of 2021, researchers from the University of Toronto reportedly developed a new coating that allows for certain liquids to move across surfaces without experiencing fluid loss.

Created in the Durable Repellent Engineered Advanced Materials (DREAM) Laboratory and led by Professor Kevin Golovin (MIE), the coating has the potential to aid in new advances in a range of fields, including medical testing.

According to the university, with current microfluidics—known as a field where small quantities of liquids are transported within tiny channels, often less than a millimeter wide—devices are limited in that they can only effectively handle liquids with high surface tension or cohesion, such as water.

These high surface tension liquids tend to stick to themselves rather than getting caught on the sides of the channel it is being transported through, unlike low surface tension liquids, such as alcohols and other solvents. Instead of moving independently, like raindrops on window glass, the low surface tension liquids stick to the sides of a given channel and have only been reported to travel about 10 millimeters before the droplet disintegrates.

Because the capillary action doesn’t apply to these materials, the transport requires an external force, such as magnetism or heat, to move the droplets. However, looking at other ways the materials could be moved, researchers looked to aspects in nature when working to develop a coating solution.

To develop the material, with microfluidics in mind, the team used two newly developed polymer coatings, both composed of liquid-like polymer brushes, however, one of which was more liquid-repellent than the other.

In strategically combining these polymers, the more repellent coating acts as a background, surrounding the less repellent coating and creating tiny channels along the surface. This channel then better allows for the liquids to move in a desired pattern or direction without losing any of the liquid during transport or requiring additional energy input.

   

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