Hydrogel-Forming Microneedles for Extracting Analytes from Biological Fluids

Microneedles can be used for transdermal delivery of drugs, biological markers, analyte extraction, etc. Swellable hydrogel microneedles are often used for these purposes, which is associated with their low production cost, ability to dissolve in the human body, and rather large volume of the transferred substance. An important feature of needles of this type is their porous structure, capable of containing a certain volume of liquid. In this work, arrays (up to 40) of microneedles were fabricated from a solution of gelatin and polyvinylpyrrolidone (PVP). The height of the needles is
$900\ \mu\mathrm{m}$
, and the diameter is
$200\ \mu\mathrm{m}$
. The microneedle arrays differed in the percentage of the components of the composition, which made it possible to evaluate the effect of the PVP content on the mass of the extracted substance. It was found that with an increase in the proportion of PVP in the material, the mass of the extracted substance increases and reaches a value of
$47\ \mu\mathrm{g}$
(for a sample with a PVP content of 66.7%).