Rapid Extraction and Detection of Biomolecules via a Microneedle Array of Wet-Crosslinked Methacrylated Hyaluronic Acid

The rapid detection of biomolecule levels in the human body is often required to monitor human health. Although swellable microneedle arrays are widely used to extract biomolecules in interstitial fluid in a minimally invasive manner, it takes 3–15 min to carry this out. Herein, we report the development of a microneedle sensor system for the rapid detection of biomolecules. By controlling the crosslinking sequence of methacrylated hyaluronic acid (MeHA) used in the microneedle array, we achieve a swelling ratio of approximately 600% in 30 s in vitro. Furthermore, an electrochemical measurement method is utilized to detect redox reaction of biomolecules extracted with the MeHA microneedle array and screen-printed electrode. One can measure 1 × 10⁻⁶ m of dopamine in 3 s in vitro and with excellent selectivity in a solution of dopamine along with 100 × 10⁻⁶ m of L-ascorbic acid and uric acid. Finally, ex vivo electrochemical analysis is performed on a gelatin phantom and porcine skin containing various concentrations of dopamine and can detect 10 × 10⁻⁶ m of dopamine within 30 s. Thus, the swellable hydrogel-based microneedle array can be applied to biomolecule sensing in interstitial fluid within a few seconds.