Scientists at Tufts University have learned how to make microscopic needles from silk for subcutaneous injection of drugs. Such an unusual medical device will make the injection painless and without a trace
A "plaster" with an array of needles is applied to the desired place on the human body. Microneedles imperceptibly pierce the upper layer of the patient's skin, gradually releasing the drug contained in the bloodstream. The miniature "syringes" are then absorbed without harming the skin or the environment.
Silk microneedles have one more plus. Most modern arrays of microscopic needles are made under aggressive conditions (we are talking, first of all, about plastic microneedles). And the drugs injected into them are very sensitive and can collapse.
Silk microneedles in this sense are much softer, since they are made from natural material. In addition, according to the assurances of the creators, their microneedles can be adjusted so that they deliver drugs at a certain speed. And also tetracycline can be added to silk microneedles, then the puncture will not introduce infection into the body. And, finally, there is no need to store such “syringes” with medicine in the refrigerator - the medicine embedded in them will not deteriorate.
The production of a "patch" with microneedles begins with an aluminum blank, which is the profile of the future array. The height of each needle reaches 500 micrometers, and the diameter of its tip is 10 micrometers. A layer of polydimethylsiloxane elastomer is first applied to the aluminum mold, which forms a negative mold.
Then the aluminum profile is removed, and silk mixed with medicine is "poured" in its place. The substance dries to form a finished array of microneedles. It is separated from the mold, treated with water vapor. The whole process takes place at normal temperature and pressure. As a test experiment, scientists from the United States added horseradish peroxidase, an enzyme often used in molecular biological research, to silk microneedles.
By varying some parameters, such as the drying time of silk, researchers have learned to adjust the rate at which the substance is released in the skin. All other features of the novelty are described in an article in the journal Advanced Functional Materials.
Of course, silk (and any other) microneedles cannot always replace ordinary syringes. However, at least in certain areas of medicine, innovative development will certainly find application.