When you get a vaccine, the momentary needle prick endows your with disease-fighting antibodies and doesn’t leave a trace. But in the future, your vaccine record may be written invisibly on your skin — and readable with just a smartphone.
A team of scientists at the Massachusetts Institute of Technology (MIT) has developed a tool capable of recording medical information on the skin using microneedles. The tool creates an invisible “quantum dot” pattern on the skin that can be revealed using a near-infrared light. In experiments done on synthetic skin and animals, the researchers found these dots can linger for up to nine months, but they likely persist for as many as five years.
"Healthcare workers could identify at a later point whether, and when, a person was vaccinated."
If humans are one day branded with these quantum dot patterns, it could allow for our vaccination history — and other medical records — to be carried on us at all times, and accessed using a phone kitted out with the right type of light scanner.
The technology is described in a paper published this week in the journal Science Translational Medicine.
Ana Jaklenec, research scientist at MIT and co-author of the study tells Inverse it’s not clear how this technology would work in the United States, where patient medical records are already kept electronically. Instead, it may be more useful in areas that still rely on pen and paper for vaccination records. But these tiny glowing dots are still strikingly futuristic compared to the digital records that contain most Americans’ medical histories.
“The goal would be to have the invisible dye administered with vaccine-like polio or measles so that healthcare workers could identify at a later point whether, and when, a person was vaccinated,” she tells Inverse.
How does quantum dot technology work?
In the lab, the quantum dots are written onto skin using a “microneedle patch” that, in the future, would also contain a vaccine. Microneedle technology is already being developed for several vaccines, including the flu vaccine.
The researchers first tested whether they could manufacture a copper-based dye that would linger in the dermis. That’s the layer of skin that a visible tattoo would occupy.
Early trials on synthetic human skin and pig skin show that, after five minutes of application, the quantum dot patterns appear under infrared light if applied to the skin. These dots are just four nanometers thick and can be configured into several patterns, from rectangles to circles to crosses.
After 12 weeks of being on the skin of rats, the dots looked like this:
The hope is that the patches would both impart a vaccine, which would be integrated into the microneedle itself, and leave the dot pattern behind, recording the vaccine.
When they co-administered a polio vaccine with the microneedle patches to rats, the team found that, two months later, the rats had high enough levels of poliovirus antigens to be considered protected from the virus. They also still had the quantum dot record on their skin, and “showed no obvious signs of irritation,” according to the study.
How would this technology be used?
The first step towards this tool being approved for use in the US is to prove that the dye used in the quantum dots is safe for humans — something this study doesn’t do.
“Next steps would be to qualify the invisible dye through the FDA and scale up the process and fabrication of the microneedles before starting a human trial,” says Jaklenec.
The idea of the technology being used in humans also comes with profound ethical considerations.
The US Food and Drug Administration regulates vaccines based on safety, but the government at large has no federal vaccination rules, which means that each state decides what their policies are for things like school enrollment. This type of technology could streamline the medical forms and immunization records that some states require for school.
But with that power also comes great responsibility. In the paper, the team writes that the technology could be used to encode any type of medical information, even though it was originally designed for vaccines. Making access to medical records via the skin could be fraught.
Medical status can be used to discriminate. For example, even being perceived as being HIV positive can lead to discrimination in general, and in the workplace. While this technology isn’t designed to track information like HIV status, it begs the question: What if it eventually was used to do so?
Jaklenec hopes that, by controlling who has access to the technology required to read the dots, private information can be kept within appropriate channels, assuring patients the same privacy that traditional medical records do.
“It’s invisible and needs specific hardware to read so hopefully that will make it difficult to read without the technology,” she says.
For now, the research is focused on vaccines. It’s about making sure that people who might not get the vaccines that can save lives do actually end up getting them. But if it’s ever to be rolled out on a wider scale, there may be a few more ethical questions that need answering.
Accurate medical recordkeeping is a major challenge in many low-resource settings where well-maintained centralized databases do not exist, contributing to 1.5 million vaccine-preventable deaths annually. Here, we present an approach to encode medical history on a patient using the spatial distribution of biocompatible, near-infrared quantum dots (NIR QDs) in the dermis. QDs are invisible to the naked eye yet detectable when exposed to NIR light. QDs with a copper indium selenide core and aluminum-doped zinc sulfide shell were tuned to emit in the NIR spectrum by controlling stoichiometry and shelling time. The formulation showing the greatest resistance to photobleaching after simulated sunlight exposure (5-year equivalence) through pigmented human skin was encapsulated in microparticles for use in vivo. In parallel, microneedle geometry was optimized in silico and validated ex vivo using porcine and synthetic human skin. QD-containing microparticles were then embedded in dissolvable microneedles and administered to rats with or without a vaccine. Longitudinal in vivo imaging using a smartphone adapted to detect NIR light demonstrated that microneedle-delivered QD patterns remained bright and could be accurately identified using a machine learning algorithm 9 months after application. In addition, codelivery with inactivated poliovirus vaccine produced neutralizing antibody titers above the threshold considered protective. These findings suggest that intradermal QDs can be used to reliably encode information and can be delivered with a vaccine, which may be particularly valuable in the developing world and open up new avenues for decentralized data storage and biosensing.