Most people are familiar with inkjet printers. But did you know that they can be used to print much more than just colored ink? Across the globe, researchers have used this technology to print light emitting polymers for flat panel displays, to create data storage devices using magnetic nanoparticles, or even to produce highly-sensitive biosensors, using arrays of proteins.
In the past two decades, there has been a push toward using inkjet technology to “print” pharmacologic agents onto small needles – producing a low-cost, painless drug delivery system. And in the latest issue of Materials Today, a team of US scientists have demonstrated the latest breakthrough in this field. Using inkjet printing, they coated arrays of microneedles with Miconazole, a drug used to treat fungal skin infections. The team also showed that the drug remained completely active throughout the printing process, by testing it on a common fungus (Candida albicans).
Scanning electron micrographs of miconazole-loaded Gantrez® AN 169 BF microneedles. (a) Front view of a miconazole-loaded Gantrez® AN 169 BF microneedle array, which shows the entire array of five microneedles above the rectangular prism-shaped substrate. (b) Front view of a single miconazole-loaded Gantrez® AN 169 BF microneedle.Inkjet printing uses piezoelectric micro-nozzles to accurately and reproducibly deposit very small liquid droplets (1 -100 pl) onto a surface. Roger Narayan and his team have applied inkjet printing to microneedles – arrays of tiny lancet-shaped polymer needles that are already being used to painlessly deliver vaccines. The accuracy of the technique means that the pharmacologic agents can be directly applied to the microneedles, without the need for further processing steps.
One of the advantages of inkjet printing is that it only a small amount of liquid is needed – in Narayan’s work, each array of microneedles (substrate area = 7.25 mm2) used just 38 µg of miconazole - but this was enough to inhibit growth of fungus in an area over seven times larger than the array size.
Narayan has said that there are wider applications to their work – “(The approach) can be used for many classes of pharmacologic agents that exhibit poor solubilities”. There are challenges remaining, such as a further reduction in the cost of suitable inkjet printing equipment, but this approach has real potential to become commercially significant. Narayan’s team continue to work in the field – and are currently looking at using a single microneedle array to simultaneously treat several medical conditions in a patient.
This news article is based on research from "Inkjet printing for pharmaceutical applications" by Ryan D. Boehm, Philip R. Miller, Justin Daniels, Shane Stafslien, and Roger J. Narayan. It appears in Materials Today, DOI: http://dx.doi.org/10.1016/j.mattod.2014.04.027. The article is available here.