have developed microparticles that can release drugs or vaccines at different
times, thus possibly eliminating the need for administering multiple injections
are being developed through 3-D fabrication to deliver multiple doses of vaccines or a drug
through a single injection
microparticles vary in structure so that they release their contents at
- Further research,
if successful, could result in better coverage of vaccines, especially in
the developing world
research was published in Science
The microparticles are
made up of a biocompatible polymer called PLGA which is molded into tiny cups
and lids with the help of silicon molds. Each cup is then filled with the drug
or vaccine, covered with the lid, and sealed with slight heating. This method
of manufacturing the microparticles is called SEAL (StampEd Assembly of polymer
Layers). Since PLGA is fully
biodegradable, the chances of a foreign body reaction are minimal
‘Microparticles developed through 3-D fabrication may be useful to deliver multiple doses of vaccines or a drug through a single injection.
The particles are
extremely tiny and can therefore be injected like any other drug or vaccine
through an 18-gauge needle. Depending on
variations in the structure, the microparticles dissolve and release their
contents at different predetermined times.
Thus, multiple doses of a vaccine,
multiple vaccines or multiple doses of drugs can be administered through a
This approach could be
particularly useful in the underdeveloped or developing nations with reduced
manpower to administer multiple vaccines and poor patient compliance. With
further development, it may be possible to develop microparticles that could
cover all the vaccines that should be administered in the first two years of
life - thus, once the child is born, he/she could be administered a single injection,
and the child would not need another vaccine for the next one to two years and
yet be protected.
The scientists carried
out several tests to evaluate their model:
- The scientists
tested the property of pulsed release from the microparticles by filling
microparticles with varying structural properties with fluorescent-
labeled dextran. They found that
the structurally-different particles released the dextran at different
times, in vitro, as well
as, when administered to mice.
Leakage of the contents before time was not observed.
- The scientists
injected mice with structurally-variant microparticles containing
ovalbumin, a substance that is used experimentally to achieve an immune
response. The particles released the ovalbumin at two different times. The final immune response obtained
with the single dose was similar to that produced by two separate
injections with double the doses.
Further research would
be needed to ensure that the medication or the vaccine remains stable within
the particles over longer durations.
The new technology of
developing such microparticles could also have several other applications in
medicine. It may be possible to bring
about the release of the medication or vaccine on the application of a stimulus
For example, in the presence of certain bacteria in the body, the
microparticles can be designed to release an antibiotic to fight against the
- McHugh KJ, Nguyen TD, Linehan AR, Yang D, Behrens AM, Rose S, Tochka ZL, Tzeng SY, Norman JJ, Anselmo AC, Xu X, Tomasic S, Taylor MA, Lu J, Guarecuco R, Langer, Jaklenec A. Fabrication of fillable microparticles and other complex 3D microstructures. Science 2017:Vol. 357, Issue 6356, pp. 1138-1142. DOI: 10.1126/science.aaf7447