Help on the skin

Each year, insufficient vaccination leads to about 1.5 million preventable deaths, primarily in developing countries. One of the factors hindering vaccination campaigns in these countries is the lack of infrastructure for storing medical records, so there is often no easy way to identify those in need of a specific vaccine.

Researchers from the Massachusetts Institute of Technology have developed a new way to record a patient's vaccination history: storing data in the form of a dye invisible to the naked eye, which is injected under the skin simultaneously with the vaccine. They showed that a new dye consisting of quantum dots can remain under the skin for at least five years. It emits near infrared light, which can be detected by a specially equipped smartphone.

Invisible recording

A few years ago, the group decided to develop a method for recording vaccination information in such a way that a centralized database or other infrastructure was not required. Many vaccines, for example, against measles, mumps and rubella, require multiple injections at certain intervals. Without accurate records, children may not receive all the necessary doses. In some areas of the developing world, it is very difficult to keep records of who has been vaccinated and whether they need additional vaccinations.

To create a decentralized medical record, researchers have developed a new type of copper-based quantum dots that emit light in the near infrared spectrum. The dots have a diameter of only about 4 nanometers, but they are enclosed in biocompatible microparticles that form spheres with a diameter of about 20 microns. This encapsulation allows the dye to persist for a long time under the skin at the injection site.

The researchers developed the dye to be delivered using microneedles rather than using a traditional syringe. Such patches are currently being developed for the delivery of vaccines against measles, rubella and other diseases.

Researchers have shown that the dye can be easily incorporated into such patches.

The microneedles used in this study are made from a mixture of soluble carbohydrates and polymethylmethacrylate, as well as a dye with quantum dots and a vaccine. When the patch is applied to the skin, the microneedles, which are 1.5 millimeters long, partially dissolve, releasing the contents for about two minutes.

By selectively loading microparticles into microneedles, patches create a pattern on the skin that is invisible to the naked eye, but can be scanned using a smartphone that has an infrared filter disabled. The patch can capture various patterns that correspond to the type of vaccine being delivered.

Effective immunization

Tests on cadaverous human skin have shown that drawings of quantum dots can be detected by smartphone cameras even after five years of simulated exposure to the sun.

The researchers also tested this vaccination strategy on rats using microneedle patches that delivered quantum dots along with the polio vaccine. They found that the rats generated an immune response similar to that of rats who received the traditional injectable polio vaccine.

The researchers are currently planning to interview health care workers in developing countries to get information on how best to keep records of this type of vaccination. They are also working to expand the amount of data that can be encoded in a single format, allowing them to include information such as the date of administration and the batch number of the vaccine.

The researchers believe that quantum dots are safe to use in this way because they are encased in a biocompatible polymer. However, further safety studies of the method are planned.

Article by K.J.McHugh et al. Biocompatible near-infrared quantum dots delivered to the skin by microneedle patches record vaccination is published in the journal Science Translational Medicine.

Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on MIT materials: Storing medical information below the skin's surface.