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Patch Device Stores Vaccine Record in Skin

Quantum dots

Quantum dots reflecting ultraviolet light (Marc Vidal, Wikimedia Commons)

19 Dec. 2019. A plastic vaccine patch is shown in lab animals to also store an invisible record of that vaccination under the recipient’s skin, displayed with a smartphone. A team from Massachusetts Institute of Technology and other institutions describe the vaccine delivery and recording patch in yesterday’s issue of the journal Science Translational Medicine.

Researchers from the lab of biomedical engineering and materials science professor Robert Langer are seeking a better process for recording a patient’s vaccine history. In many parts of the world, and even in some advanced societies, medical records are uneven in quality or consistency, if they exist at all. As a result, say the authors, an estimated 1.5 million preventable deaths occur each year due to lack of vaccination.

“In order to be protected against most pathogens, one needs multiple vaccinations,” says Ana Jaklenec, research scientist and co-senior author of the paper in an MIT statement. “In some areas in the developing world, it can be very challenging to do this, as there is a lack of data about who has been vaccinated and whether they need additional shots or not.”

To provide a safe and reliable way to record an individual’s vaccine, the researchers devised a patch to deliver the vaccine, while at the same time deliver a record of that vaccine in the recipient’s skin. A bio-compatible plastic patch with tiny needles to penetrate only the very outer layers of skin with little or no pain has been shown as an inexpensive and feasible drug delivery method, including for vaccines. A report in August on Science & Enterprise from colleagues at MIT is a recent example.

Langer, Jaklenec, and colleagues fabricated their vaccine delivery patch from polyvinyl acetate, or PVA, a bio-compatible polymer, with microscale needles. The needles, 1.5 millimeters long, are made from a combination of PVA and sugar that dissolves to release the vaccine and a fluorescent dye. The dye contains nanoscale semiconducting crystals called quantum dots that are invisible to the naked eye, but still respond to light.

In this case, the quantum dots are made with a core of copper indium selenide and a shell of zinc/aluminum sulfide to respond to near-infrared light rays, as well as resist bleaching from exposure to sunlight. The quantum dots are delivered under the skin’s surface inside clear, common PMMA or acrylic polymer spheres for long-term wear.

The team also designed a reading system using a smartphone’s camera. To read quantum dots, the camera is outfitted with a condenser and filters added to the phone’s case to emit a near-infrared signal that penetrates the outer skin layer and excites the quantum dots. The same equipment then filters out background light and captures responses from the quantum dots. The team also wrote an algorithm using a public image analysis and machine learning network to interpret the signals and information patterns from the quantum dots.

The researchers tested the vaccine delivery and recording patch with lab rats. The team first tested the patch in live rats without a vaccine for evidence of toxicity and other adverse reactions, and found localized reactions to skin punctures, but otherwise the patches are well tolerated by the animals. Tests of the patch in rats with the Salk polio vaccine show the device delivers equivalent amounts of the vaccine and produces an immune response similar to conventional injections. Separate tests with rats show quantum dots delivered by the patch can be read and interpreted with a smartphone up to nine months following their application.

The researchers now plan to expand the amount of information that can be stored and retrieved with quantum dots, and will survey health care workers in developing areas on implementing the process. MIT applied for a patent on the technology, with several of the authors listed as inventors.

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