No one likes getting injections (apart from drug addicts maybe?). Well, research from the University of Texas at Dallas, US, may be able to provide a painless alternative. The research team reports a technique for 3D printing microneedle arrays, in a position to deliver medicine via a simple patch applied to the skin. Microneedles have been attracting attention in the medical community for a while, because they provide a means for unskilled carers to deliver medicine safely, with much less risk of an infection than conventional transdermal injection or syringe, and better shelf-life than medication stored as injectable liquids. They include arrays of polymer needles, ideally around 100 micrometers wide, which could be coated with a drug. Alternatively, the medicine could be incorporated into the polymer so that the needles break off within the skin and dissolve to release their dose.
Manufacturing microneedles with the correct dimensions, however, isn’t an easy process. They’re usually made out of a reusable template, which is difficult to produce. Costly photolithography equipment is required to complete the process. The group of researchers at Dallas, led by Jeremiah Gassensmith, looked to use 3D printing techniques to make microneedles from polylactide, a non-toxic, biodegradable and renewable polymer which is permitted to be used in dissolvable stitches. Unfortunately, the printing techniques which are capable of producing features smaller than 100 micrometers aren’t compatible with the biodegradable polymer required. Gassensmith’s team instead used fused deposition modeling (FDM), a 3D printing approach that works efficiently with polylactide. However, it has lower resolution.
Utilizing FDM printing, the researchers produced polylactide pillars with a width of 400-600 micrometers, but couldn’t achieve the tapered needle form that they needed. To accomplish this, they turned to chemical etching to finish the process.Polylactide dissolves in water at mildly acidic or alkaline pH. In fact, the slight acidity of skin is what permits the microneedles to dissolve once they’ve broken off in the patient’s skin. The team from Gassensmith used an alkaline solution of potassium hydroxide to etch away at the pillars, producing barbed needle-like constructions with tip sizes between one and 55 micrometers.
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These microneedles were then tested on pig skin, exhibiting that they could deliver a dose of a dye molecule beneath the skin, mimicking how a drug can be delivered. The researchers also discovered that applying a light sideways force to the microarray led to 84% of the needles breaking off within the skin, which may very well be used to deliver medicine as the needles dissolve slowly.
Most significantly, the microneedles could be quickly and cheaply produced, which permits scientists to evaluate different needle sizes and designs, hopefully resulting in the optimum microarray for pain-free drug delivery.
Research into alternative ways to deliver medication inside the body has become increasingly popular in recent times. In Jun 2017, scientists from Emory University and Georgia Tech developed a sticker patch equipped with microneedles that could possibly be used to deliver vaccines. In February, researchers from the University of Copenhagen launched a study suggesting edible QR codes could be the next step in delivering drugs.
No matter where the medical community goes, it’s safe to assume that patients all over the world would welcome painless injections or no injections at all. Think about a world in which parents don’t need to persuade their kids that the scary-looking needle isn’t that bad, even when it’s, in reality, it is terrifying and painful.